U.S. patent application number 16/549425 was filed with the patent office on 2020-02-27 for data acquisition methods and apparatus for a network connected led driver.
The applicant listed for this patent is Lumastream Canada ULC. Invention is credited to Kyle HATHAWAY, Steven LYONS, Jason NEUDORF.
Application Number | 20200068680 16/549425 |
Document ID | / |
Family ID | 69583939 |
Filed Date | 2020-02-27 |
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United States Patent
Application |
20200068680 |
Kind Code |
A1 |
NEUDORF; Jason ; et
al. |
February 27, 2020 |
DATA ACQUISITION METHODS AND APPARATUS FOR A NETWORK CONNECTED LED
DRIVER
Abstract
A lighting system including monitoring of input power and output
power parameters to a set of lighting loads to detect power faults
and/or anomalies. The set of sensing circuits include primary side
and secondary side sensing circuits that communicate with a set of
monitoring circuits to process the information supplied by the
sensing circuits. If a fault and/or anomaly is sensed or detected,
a signal is transmitted to provide an alert.
Inventors: |
NEUDORF; Jason; (Kitchener,
CA) ; LYONS; Steven; (Kitchener, CA) ;
HATHAWAY; Kyle; (Kitchener, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lumastream Canada ULC |
Calgary |
|
CA |
|
|
Family ID: |
69583939 |
Appl. No.: |
16/549425 |
Filed: |
August 23, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62721678 |
Aug 23, 2018 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05B 45/20 20200101;
H05B 45/10 20200101; H05B 47/19 20200101; H05B 45/14 20200101; H05B
47/22 20200101; H05B 45/355 20200101; H05B 45/50 20200101 |
International
Class: |
H05B 33/08 20060101
H05B033/08 |
Claims
1. A light emitting diode (LED) driver comprising: a set of sensing
circuits, the set of sensing circuits including a set of primary
side sensing circuits and a set of secondary side sensing circuits;
and a data acquisition apparatus including: a primary side
monitoring circuit for receiving and processing primary side data
from the set of primary side sensing circuits; a secondary side
monitoring circuit for receiving and processing secondary side data
from the set of secondary side sensing circuits; a lighting status
apparatus and a communication interface; wherein the lighting
status apparatus and primary side monitoring circuit determine if a
power anomaly or fault has occurred based on the primary side data
and lighting status apparatus and the secondary side monitoring
circuit determine if a power anomaly or fault has occurred based on
the secondary side data; wherein if occurrence of a power anomaly
or fault is determined, the communication interface transmits a
signal to an external controller.
2. The LED driver of claim 1 further comprising an isolation
barrier for dividing the LED driver into a primary side and a
secondary side.
3. The LED driver of claim 2 wherein the isolation barrier is
located within a DC/DC power converter.
4. The LED driver of claim 3 wherein the primary side comprises a
power factor conversion apparatus.
5. The LED driver of claim 2 wherein the secondary side comprises:
a DC output bus connected to the DC/DC power converter; a power
monitor connected to the DC output bus; and a set of output power
channels connected to an output of the power monitor, the set of
output power channels associated with a set of light loads.
6. The LED driver of claim 5 wherein the set of output power
channels and the set of light loads are associated in a one-to-one
relationship.
7. The LED driver of claim 1 wherein the set of sensing circuits
comprise voltage sensing circuits and current sensing circuits.
8. The LED driver of claim 1 wherein the data acquisition apparatus
further comprises a data isolator for isolating the primary side
monitoring circuit from the secondary side monitoring circuit.
9. The LED driver of claim 1 wherein the data acquisition apparatus
further comprises an auxiliary power source.
10. The LED driver of claim 1 wherein the data acquisition
apparatus further comprises: a visual display for displaying an LED
driver status.
11. The LED driver of claim 10 wherein the data acquisition
apparatus further comprises: a set of dials for receiving input
from an user.
12. A method of determining faults within a light emitting diode
(LED) driver comprising: determining primary side and secondary
side data via a set of primary side and secondary side sensing
circuits; processing the primary side data, via a primary side
monitoring circuit, to determine if a primary side power anomaly or
fault has occurred; processing the secondary side data, via a
secondary side monitoring circuit to determine if a secondary side
power anomaly or fault has occurred, and transmitting a signal to a
lighting system controller if it is determined that a power anomaly
or fault has occurred.
13. The method of claim 12 further comprising: storing the primary
side and secondary side data for retrieval by the data acquisition
lighting system controller.
14. The method of claim 12 wherein processing the primary side data
comprises: comparing the primary side data with an expected value
range; and determining that a primary side power anomaly has
occurred if the primary side data is not within the expected value
range.
15. The method of claim 12 wherein processing the secondary side
data comprises: comparing the secondary side data with an expected
value range; and determining that a secondary side power anomaly
has occurred if the secondary side data is not within the expected
value range.
Description
CROSS-REFERENCE TO OTHER APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Application No. 62/721,678 filed Aug. 23, 2018, the contents of
which are hereby incorporated by reference.
FIELD
[0002] The disclosure is generally directed at lighting apparatus,
and more specifically, at data acquisition methods and apparatus
for a network connected light emitting diode (LED) driver.
BACKGROUND
[0003] The integration of lighting systems with Internet of Things
(IoT) devices as part of an Internet connected network enables such
systems to remotely monitor, collect, and analyze data in order to
improve, optimize and/or control lighting system performance while
providing economic benefits.
[0004] One of the challenges of an IoT network connected lighting
system is the integration of multiple IoT devices that include
sensors and associated monitoring and data collection apparatus at
various locations throughout the lighting system. Multiple external
sensors are required to be connected back to a centralized control
apparatus, integrated within multiple light fixtures and/or
externally connected to multiple power conversion sources such as
light emitting diodes (LED) drivers at different locations
throughout the lighting system.
[0005] As a result, such IoT lighting system architectures increase
the complexity and cost of IoT device integration for a lighting
system that includes one power source with a single output power
channel connected to a single light fixture.
[0006] Therefore, there is provided a novel method and apparatus
for a network connected light emitting diode (LED) driver.
SUMMARY
[0007] With the adoption of high luminous efficacy solid state
lighting (SSL) devices, such as light emitting diodes (LEDs), for
general illumination applications that are also inherently direct
current (DC) components, the practical application of a distributed
low voltage direct current (LVDC) system architecture can be
achieved. A distributed LVDC lighting system architecture includes
a centralized power source with multiple output power channels that
provide safe and accessible power and control to multiple light
fixture loads. The centralized aspect of the power source, such as,
but not limited to, a LED driver for powering multiple LED loads,
may include an internal sensing and monitoring apparatus for
monitoring external inputs into the lighting system as well as
external loads connected to the lighting system. The disclosure
provides a system and method of acquiring lighting system status in
order to control as well as detect lighting system anomalies or
faults and improve and/or optimize the performance of a network
connected IoT lighting system.
[0008] In one aspect of the disclosure, there is provided a light
emitting diode (LED) driver including a set of sensing circuits,
the set of sensing circuits including a set of primary side sensing
circuits and a set of secondary side sensing circuits; and a data
acquisition apparatus including a primary side monitoring circuit
for receiving and processing primary side data from the set of
primary side sensing circuits; a secondary side monitoring circuit
for receiving and processing secondary side data from the set of
secondary side sensing circuits; a lighting status apparatus and a
communication interface; wherein the lighting status apparatus and
primary side monitoring circuit determine if a power anomaly or
fault has occurred based on the primary side data and lighting
status apparatus and the secondary side monitoring circuit
determine if a power anomaly or fault has occurred based on the
secondary side data; wherein if occurrence of a power anomaly or
fault is determined, the communication interface transmits a signal
to an external controller.
[0009] In another aspect, the LED driver further includes an
isolation barrier for dividing the LED driver into a primary side
and a secondary side. In another aspect, the isolation barrier is
located within a DC/DC power converter. In yet another aspect, the
primary side includes a power factor conversion apparatus. In a
further aspect, the secondary side includes a DC output bus
connected to the DC/DC power converter; a power monitor connected
to the DC output bus; and a set of output power channels connected
to an output of the power monitor, the set of output power channels
associated with a set of light loads. In yet another aspect, the
set of output power channels and the set of light loads are
associated in a one-to-one relationship.
[0010] In another aspect, the set of sensing circuits include
voltage sensing circuits and current sensing circuits. In an
aspect, the data acquisition apparatus further includes a data
isolator for isolating the primary side monitoring circuit from the
secondary side monitoring circuit. In yet a further aspect, the
data acquisition apparatus further includes an auxiliary power
source. In another aspect, the data acquisition apparatus further
includes a visual display for displaying an LED driver status. In
another aspect, the data acquisition apparatus further includes a
set of dials for receiving input from a user.
[0011] In another aspect of the disclosure, there is provided a
method of determining faults within a light emitting diode (LED)
driver including determining primary side and secondary side data
via a set of primary side and secondary side sensing circuits;
processing the primary side data, via a primary side monitoring
circuit, to determine if a primary side power anomaly or fault has
occurred; processing the secondary side data, via a secondary side
monitoring circuit to determine if a secondary side power anomaly
or fault has occurred, and transmitting a signal to a lighting
system controller if it is determined that a power anomaly or fault
has occurred.
[0012] In a further aspect, the method further includes storing the
primary side and secondary side data if it is determined that no
power anomaly or fault has occurred. In yet a further aspect,
processing the primary side data includes comparing the primary
side data with an expected value range; and determining that a
primary side power anomaly has occurred if the primary side data is
not within the expected value range. In yet another aspect,
processing the secondary side data includes comparing the secondary
side data with an expected value range; and determining that a
secondary side power anomaly has occurred if the secondary side
data is not within the expected value range.
DESCRIPTION OF THE DRAWINGS
[0013] Embodiments of the present disclosure will now be described,
by way of example only, with reference to the attached Figures.
[0014] FIG. 1 is a block diagram of a network connected light
emitting diode (LED) driver;
[0015] FIG. 2a is a schematic diagram of a LED driver internal
voltage sense point;
[0016] FIG. 2b is a schematic diagram of a LED driver internal
current sense point;
[0017] FIG. 3 is a block diagram showing an embodiment of a power
channel implemented as a current source;
[0018] FIG. 4 is schematic diagram of apparatus for sensing the
on-time of a gate drive semiconductor switch;
[0019] FIG. 5 is a table showing data acquisition parameters and
various primary side and secondary side sense points internal to an
LED driver;
[0020] FIG. 6 is a flowchart of an embodiment of a of data
acquisition method for a lighting system;
[0021] FIG. 7 is a schematic diagram of a network connected
lighting system for IoT applications;
[0022] FIG. 8 is block diagram of an another embodiment of a
network connected LED driver;
[0023] FIG. 9 is a block diagram of an alternate embodiment of a
network connected LED driver with data acquisition capabilities;
and
[0024] FIG. 10 is table showing various displayable parameters
representing different lighting system statuses.
DETAILED DESCRIPTION
[0025] The disclosure is directed at a method, system and apparatus
for a network connected light emitting diode (LED) driver. In one
embodiment, the disclosure includes an LED driver having a
plurality of sensors that, depending on its location within the LED
driver, communicate with a primary side or secondary side fault
monitoring circuit. Based on signals received from the plurality of
sensors, the monitoring circuits determine if a fault has occurred
and performs the necessary actions to handle the detected
fault.
[0026] Turning to FIG. 7, a schematic representation of a network
connected lighting system in its operational environment is shown.
In the current embodiment, the lighting system is controlled via at
least one Internet of Things (IoT) application. These applications
may be executing on a peripheral device, servers and the like. The
lighting system 90 includes at least one LED driver 100 and a
lighting system controller 160 preferably with data acquisition
capabilities. The LED driver 100 controls or provides power to a
set of lighting loads 140 which may or may not form part of the
lighting system 90. In other words, the system and method of the
disclosure may be implemented as a stand-alone lighting system or
may be integrated or retro-fitted into an existing lighting system
or installed for existing lighting loads. The lighting loads 140
may be mounted remote from the lighting system 90.
[0027] For general illumination applications and tunable white
lighting applications, the light loads 140 may include different
types of LEDs such as, but not limited to, mid power LEDs, high
power LEDs or organic LEDs (OLEDs) which require a constant DC
drive current. For cove lighting applications, the light loads 140
may include LED tape or strip lighting that requires a constant
voltage, such as 24 Vdc.
[0028] The lighting system 90 is connected to an IoT gateway 180
which provides a communication link between the lighting system 90
and peripheral devices, seen as a laptop 182 or a cellphone or
Smartphone.TM. 184. Other peripheral devices are also considered
and will be understood by one skilled in the art. The lighting
system 90 may also be connected to a Cloud computing system 190 via
the gateway 180. The cloud computing system 190 may include servers
186 to store, manage and process data.
[0029] In the event of an anomaly or fault within the lighting
system 90, the data acquisition lighting system controller 160
transmits data associated with and/or notification of such an event
to the various peripheral devices 182, 184 or to cloud computing
system 190. Communication between the various peripheral devices
182, 184 and the lighting system 90 can be performed via one or a
combination of various standards based wired and/or wireless
technology. Wireless protocols can include Wifi.TM., Z Wave,
Zigbee, Bluetooth.TM. Mesh and variations of such. In this manner,
individual(s) can be alerted to the detected fault by the lighting
system 90 via a message to the peripheral device. Communication
between the IoT gateway 180 and the cloud computing system 190 is
preferably via an internet protocol (IP) 188. In one embodiment,
the cloud computing system 190 includes a set of servers 186 that
may store data as well as conduct trend analysis based on
information transmitted by the LED driver 100.
[0030] Turning to FIG. 1, a schematic block diagram of a first
embodiment of a lighting system is shown. In the current
embodiment, the lighting system 90 includes the network connected
LED driver 100 and the data acquisition lighting system controller
160.
[0031] The LED driver 100 includes a power factor correction (PFC)
converter 200 which receives power from an AC mains voltage source
or input 120. The voltage source 120 is typically an external
component and not part of the lighting system 90. The PFC circuit
or converter 200 includes a voltage and/or current sensing circuit
206 along with a gate driving sensing circuit 208. The PFC
converter 200 is connected to a DC/DC power converter 240 that
includes a voltage and/or current sensing circuit 244 and a
galvanic isolation barrier 242. The DC/DC power converter 240 is
connected to a DC output bus 260 that includes a voltage and/or
current sensing circuit 262. The DC output bus 260 is further
connected to a power monitor 300, including a voltage and/or
current sensing circuit 302, that is connected to a plurality of
output power channels 320. Each of the plurality of output power
channels 320 may include a voltage and/or current sensing circuit
322. An output of each of the output power channels 322 is
connected to an individual light load 140 which may or may not be
part of the lighting system 90. In some embodiments, the lighting
system may be integrated with existing lighting loads, and in some
embodiments, the lighting system may include its own lighting loads
that are mounted in remote areas of the site being illuminated.
[0032] With respect to the galvanic barrier 242, the PFC circuit
200 may be seen as being on a primary side (of the galvanic barrier
242) while the DC output bus 260, power monitor 300 and output
power channels 320 may be seen as being on a secondary side (of the
galvanic barrier 242).
[0033] The LED driver 100 further includes a data acquisition
apparatus 500 that includes a primary side monitoring and fault
detection or primary side monitoring circuit 510 and a processing
unit 540. It will be understood that the primary side monitoring
circuit may also be in the form of a processor. In the current
embodiment, both the monitoring circuit 510 and the processing unit
540 are coupled to at least one data-isolator device 520 including
a galvanic barrier, or galvanic isolation barrier 522 to provide
galvanic isolation, using either magnetic or optical isolation
functionality, to isolate the primary side monitoring and fault
detection circuit 510 from the processing unit 540.
[0034] The processing unit 540 includes a secondary side monitoring
and fault detection or secondary side monitoring circuit 542, a
lighting system status apparatus 544 and a communication interface
546. The communication interface 546 enables communication between
LED driver 100 and the external data acquisition lighting system
controller 160, such as to transmit lighting system status
information. Communication between the interface 546 and the
controller 160 is preferably via known communication protocols.
[0035] The data acquisition apparatus 500 may further include
non-volatile memory 580 such as flash memory to store data
collected by or from the primary side monitoring circuit 510 and
the secondary side monitoring circuit 542. The memory 580 is
preferably connected to the processing unit 540.
[0036] Although not shown, the processing unit 540 may further
include any combination of components including a central
processing unit (CPU), microcontroller, multiprocessor, a digital
signal processor (DSP), and/or application specific integrated
circuit (ASIC) capable of performing A/D and/or D/A conversion. The
processing unit, or processor, 540 may further include modules for
executing firmware/software programs.
[0037] The primary side monitoring circuit 510 is connected to
receive information (such as in the form of a data signal) from the
PFC converter 200 and DC/DC power converter 240. The secondary side
monitoring and fault detection circuit 542 is connected to receive
information from the DC output bus 260, the power monitor 300 and
the output power channels 320. More specifically, the primary side
monitoring and fault detection circuit 510 and associated voltage
and/or current sense circuits on the primary side including voltage
and/or current sense or sensing circuits 206, 210 and 244 as well
as gate drive sensing circuit 208 are connected to the PFC power
stage 200, the AC mains input 120, and the primary side of DC/DC
power converter 240 via primary side data signal lines 420.
Components on the secondary side of the DC/DC power converter 240
such as the DC output bus 260, power monitor 300, and output power
channels 320 and their associated voltage and/or current sense
circuits 262, 302 and 322 are connected to the secondary side
monitoring and fault detection apparatus or circuit 542 via
secondary side communication data signal lines 400. The
communication between the primary side monitoring and fault
detection circuit 510 and the lighting system module 544 may be
assisted by the data-isolator device 522 via the processor 540.
[0038] In operation, the PFC converter 200, the DC/DC power
converter 240, the DC output bus 260, the power monitor 300 and the
output power channels 320 convert and transfer input AC power (from
the AC mains input 120) into DC power suitable for operation, or
powering, of the light loads 140. The galvanic barrier 242 provides
electrical isolation between the voltage supplied by the AC mains
input 120 on the primary side of the LED driver 100 from the
secondary side DC output bus 260. As will be understood, not all
components or circuit blocks and interconnections between such
components are shown as they will be understood by one skilled in
the art. For instance, the primary side of the power circuit or LED
driver 100 may include components such as, but not limited to, an
inrush current circuit, an EMI filter and/or a bridge rectifier.
The LED driver 100 may also include a primary controller for
regulating operation of the PFC converter 200 and the DC/DC power
converter 240. Similarly, the secondary side of the LED Driver 100
may include an isolated feedback circuit coupled to a primary
controller for regulating the DC output bus 260 to a fixed voltage
level.
[0039] In a specific embodiment of operation of the LED driver 100,
the PFC converter 200 operates as a switch mode boost converter and
receives an AC sinusoidal mains input voltage in the range of 90
Vrms to 305 Vrms. This AC voltage is rectified and converted to a
nominal 450 Vdc bus voltage that is then supplied to the DC/DC
power converter 240.
[0040] The DC/DC converter 240 coupled to the DC output bus 260 may
be seen as an isolated switch mode buck converter employing a half
bridge LLC resonant topology. The DC output bus 260 is preferably,
but not necessarily, regulated to maintain a near constant safety
extra low voltage (SELV) output such as, for example, 42.4 Vdc. It
is understood that other output voltages, not exceeding 60 Vdc, are
possible.
[0041] The power monitor 300 monitors power directly transferred to
the set of power channels 320 from the DC output bus 260 and
indirectly to the set of light loads 140. The voltage and/or
current sensing circuit 302 within the power monitor 300 may be
connected in series to the positive side of the DC output bus 260
to sense and/or measure a proportional DC voltage level of the bus
current transferred to the set of output power channels 320 and
then transmits this sense or measured value to the secondary side
monitoring circuit 542.
[0042] In a preferred embodiment, the output power channels 320 may
be implemented as either a constant current source or a constant
voltage source. A constant current source configuration is
preferably implemented with a switch mode buck topology and
hysteretic control since this implementation provides a regulated
constant current output that may be configurable for various DC
drive currents such as, but not limited to, 175 mA, 350 mA, 500 mA,
and 700 mA. A constant voltage source is preferably implemented
with a switch mode buck topology with negative feedback control
where the output bus voltage is stepped from 42.4 Vdc to a
regulated 24 Vdc output.
[0043] In one embodiment, the primary side monitoring and fault
detection apparatus or circuit 510 includes a microcontroller with
random access memory (RAM) and a Universal Asynchronous Receiver
Transmitter (UART) to store and transmit and receive data in a
bidirectional manner. In another embodiment, the primary side
monitoring and fault detection circuit 510 includes a
microcontroller with memory, at least one UART and firmware to
receive data via the data lines 420, store the data in memory,
execute various firmware programs and transmit data to the data
isolator 520.
[0044] The primary side data lines 420 and secondary side data
lines 400 transmit analog signals to the primary side monitoring
circuit 510 and secondary side monitoring circuit 542,
respectively, to assist in the monitoring and/or detection
performed by the respective monitoring and fault detection
apparatus. Both primary and second monitoring and fault detection
circuits 510 and 542 may include ancillary circuits to scale, level
shift, and filter the various signals received from their
respective data signal lines.
[0045] The primary and secondary side sensing circuits may include
voltage divider networks such as resistor networks to scale voltage
values or precision resistors for current sensing. In one
embodiment, existing sense circuits currently required for
operation of the LED driver 100 may also be used for data
acquisition purposes.
[0046] For example, in one embodiment, one of the sensing circuits
206 or 208 of the PFC convertor 200 may be a resistor divider
network for sensing and regulating the 450 Vdc bus. Also, the
sensing circuit 244 within the DC/DC converter 240 may be a sense
resistor or current transformer that senses a primary side current
for overload and fault protection. On the secondary side of the LED
driver 100, the sensing circuit 262 of the DC output bus 260 may be
a resistor voltage divider network to regulate the DC output bus
260. In another embodiment, at least one of the output power
channels 320 may include a switch mode buck converter for a
constant current output and a current sensing circuit, in the form
of a current sense resistor, to regulate DC current supplied to the
light load 140. As will be understood, these are some examples of
the different voltage and/or current sensing circuits, however,
others may be contemplated for the current disclosure.
[0047] Although external to the LED driver 100, the data
acquisition lighting system controller 160 preferably includes a
communication interface to receive lighting system status
information from the LED driver 100. The controller 160 may include
other components to implement lighting control functions, such as,
but not limited to, transmitting dimming intensity information to
the LED driver 100 to control the light loads 140.
[0048] In one embodiment of operation of the data acquisition
apparatus 500, the power quality of the AC mains input voltage 120
is monitored by proxy within the LED driver 100 by sensing a PFC
bus voltage via sensing circuit 206 and/or a PFC boost converter
switch on-time represented via sensing circuit or sense point 208
within the PFC boost converter 200. Power quality anomalies that
are detected may include AC mains transients such as, but not
limited to, voltage dips or swells, voltage interruptions or the
recycling of the AC input power by an end user. The sensing
circuits transmit the measurements that are detected and the
lighting system apparatus 544 processes the received measurements
to determine if a fault or anomaly has occurred.
[0049] In one embodiment, the lighting system status apparatus 544
filters data by comparing it to predetermined limits or ranges. It
may also analyze a snap shot of data by completing a statistical
analysis. The filtering and analysis of data completed within the
LED driver can reduce the amount of data transmitted in a wired
and/or wireless network connected lighting system mitigating
potential data traffic congestion and latency issues where detected
anomalies require a priority response.
[0050] The signals or measurement sensed by some or all of the
primary side sensing circuits or points 210, 206, 208, and 244 are
preferably collected over a predetermined time period. In a
preferred embodiment, the measurements or signals are collected
over a duration of 18 ms at 1 ms intervals approximately
corresponding to an AC mains voltage cycle or period. The
collection of signals, which may be referred to as a snap shot of
data, is temporarily stored in random access memory (RAM) within
the primary side monitoring and fault detection circuit or
apparatus 510. The set of eighteen (18) samples is then transmitted
as a packet from the primary side monitoring and fault detection
circuit 510 to the lighting system status apparatus 544 within the
processing unit 540. In this mode of operation, a data snap shot is
taken every 0.5 seconds (seen as a data snap shot time interval)
for transmission via data isolator 520 such as an asynchronous
serial communication apparatus.
[0051] In the event of one or more input AC power quality
anomalies, the number of samples in the snap shot set as well as
the snap shot time interval and subsequent transmission rate of
packets can be increased or decreased depending on the priority
assigned to analyze data from the sensing circuits 206, 208, 210
and 244.
[0052] For example, if there is a repetitive power quality issue
with a lighting system installation or a lighting load, the number
of samples can be increased from 18 samples to 36 samples per AC
mains cycle and/or the snap shot interval and transmission rate of
the packet of data can be increased to include every AC mains cycle
or 16.6 ms from every 0.5 seconds snap shot interval. This may be
controlled by the processing unit 540 based on the determination or
determinations by the primary side and/or secondary side monitoring
circuits.
[0053] The data acquisition apparatus 500 may also monitor the LED
driver 100 for anomalies or fault conditions on the secondary side
of the driver 100 via the secondary side fault detection circuit
542. Secondary side anomalies can include, but are not limited to,
overload or short circuit of output power channels 320 and/or light
loads 140, disconnection or failure of light loads and reverse
polarity or improper interconnection between light loads. Internal
fault conditions can also include a failure of an output power
channel.
[0054] In one example, sensing circuit 262 (within DC output bus
260) may monitor the output bus voltage from the DC output bus 260
and current sensing circuit 302 may monitor current for a set of
associated power channels 320 and light loads 140. Either or both
voltage and current sensors or sensing circuits 322 (within the
individual output power channels 320) may monitor output cable and
light load voltages and current being delivered to each individual
light load 140.
[0055] A snap shot of secondary side sensor data from all or any
combination of the sensing circuits 262, 302 and 322 may be
collected at predetermined intervals such as every five (5)
minutes. The snap shot time interval for the secondary side data
can also be increased or decreased for each sensing circuit
collectively or individually depending on the priority of the
sensed data as well as the need to retain this data in the
non-volatile memory 580 for future retrieval by the data
acquisition lighting system controller 160.
[0056] The lighting system status apparatus 544 preferably analyzes
data or measurements submitted from the primary side and secondary
side monitoring circuits over a predetermined period of time. For
example, in terms of filtering, the lighting system apparatus 544
can select a smaller set of data such as a low or minimum or high
or maximum values from a sensing circuit. In terms of analysis, the
data from the sensing circuits can be compared to calculated
statistical parameters based on historical data and/or to
predetermined limits and/or ranges for each sensing circuit prior
to logging of the data to memory 580.
[0057] Calculated statistical parameters based on at least one or
more snap shots of data over a predetermined period of time from
various internal sense points can include but are not limited to
average or arithmetic mean, median, standard deviation and/or
moving average. The lighting system status apparatus 544 can also
filter this data for specific characteristics or other
predetermined criteria.
[0058] The data (or snap shot of data) collected over the
predetermined time interval whether or not it is within
predetermined parameter limits or ranges, is preferably logged into
non-volatile memory 580 for later retrieval by the data acquisition
lighting system controller 160 via communication interface 546. If
the data collected or sensed is determined to be out of the
predetermined or expected range, a notification of the anomaly or
fault and its associated data is queued for priority transmission
to the data acquisition lighting system controller 160. In the
event of an anomaly or fault, the data acquisition lighting system
controller 160 prioritizes the event data for transmission to the
cloud computing system 190. The cloud computing system 190 may be
part of a building management service that would provide building
facility personnel with actionable data to respond to the lighting
system fault(s) or anomalies. If the data is within predetermined
parameter limits or ranges, the data acquisition lighting system
controller 160 may also poll the LED driver 100 at regular
intervals to retrieve data and transmit this data to the cloud
computing system 190. The data may be stored on a data server in
the cloud for further lighting system improvements as part of a
building management service.
[0059] In an embodiment, with reference to the lighting system
status apparatus 544, the analysis of a power quality anomaly, such
as a voltage interruption, by the lighting system status apparatus
544 can include the sampling of the PFC bus voltage by the sensing
circuit 206.
[0060] In this example, the PFC converter voltage is regulated to a
nominal 450 Vdc with a predetermined load and line regulation range
of +/-2% or a minimum limit of 441 Vdc and a maximum limit of 459
Vdc. In the event of an interruption of AC mains voltage for a half
cycle duration (8.3 milliseconds), the PFC bus voltage begins to
collapse and drops below the +/-2% regulation range. After the AC
mains voltage is restored, the PFC voltage control loop restores
the bus voltage to the nominal 450 Vdc with a typical overshoot
above the 2% regulation range lasting for several milliseconds.
[0061] Sampling the PFC bus voltage at a 1 ms rate will detect the
initial drop in voltage as well as the recovery to its regulation
range of +/-2%. The lighting system status apparatus 544 computes
this out of bounds, or power, anomaly and prioritizes this event
for notification and transmission to the lighting system controller
160. As some detected faults and/or anomalies may result in a
noticeable degradation of lighting quality, such as a noticeable
drop of light intensity or black out that a building management
service may need to investigate especially on an on-going basis,
this fault or anomaly may be designated as a priority fault that
needs to be addressed in a more accelerated manner. In this
example, substandard quality of AC mains electrical power whereby
voltage and/or frequency are not within limits may require
mitigation approaches such as power conditioning apparatus to
improve lighting system performance.
[0062] In another embodiment, apparatus for detecting a power
quality anomaly on the primary side such as an AC mains transient
voltage swell may include apparatus to sense the gate drive on-time
of the switch via sense point 208 in the PFC converter 200 and
subsequently determine the peak AC mains voltage by proxy. In one
embodiment, a precise AC mains voltage peak value is determined by
sense point 208 and a general AC mains voltage transient event may
be detected by sense point 206 on the PFC bus but would not be able
to determine the "degree" of the event.
[0063] In this example, the on-time is sensed by a counter within
the primary side monitoring and fault detection apparatus 510 that
only counts when the PFC switch is switched on. The monitoring of
switch gate on-time can determine the instantaneous input level of
the AC mains voltage, particularly peak voltage levels, where the
PFC converter 200 is operating in either critical conduction mode
or in continuous conduction mode and under load conditions.
[0064] For reference, in a boost PFC converter topology, the
instantaneous AC mains voltage can be expressed as:
V.sub.acinst=V.sub.pfc*(1-D) Eq. 1
where V.sub.pfc=output bus PFC voltage
[0065] The duty cycle is expressed as:
D=t.sub.on/T.sub.per Eq. 2
[0066] where D is duty cycle of the PFC switch with on-time
duration t.sub.on over a switch period of T.sub.per.
[0067] In the boost PFC converter 200, with a transition mode of
operation, both the duty cycle, D, and corresponding switching
frequency vary with the instantaneous value of the AC mains
voltage. During a 1 ms snap shot interval of the sinusoidal AC
mains voltage cycle, an average duty cycle D.sub.avg includes
multiple PFC switching cycles and multiple on and off durations of
the switch.
[0068] This average duty cycle (D.sub.avg) can be determined by a
counter that increments during the on-time duration of the switch
over a 1 ms snap shot interval. For example, at an AC mains input
voltage of 277 V.sub.ac, if the counter has a given maximum or high
count of 250 with 4 microsecond increments, over the 1 ms interval
corresponding to a portion of the AC mains voltage mains cycle, the
counter starts with an initial value of 124 and increments to a
final value of 157 representing an on-time count of 33 for the PFC
switch. Based on the on-time count and corresponding calculated off
time count, the average duty cycle can be calculated from Eq.
2.
By sensing the PFC converter bus voltage 206 measuring 450 Vdc, the
instantaneous peak voltage V.sub.acinst, and V.sub.rms can be
determined as shown in Table 1.
TABLE-US-00001 TABLE 1 AC Mains sensing by proxy Calculated Input
On- Off- Sensed PFC Calculated Calculated Voltage Time Time Bus
Voltage Duty Cycle Vacinst Vrms = Count Count Vpfc (Vdc) `Davg`
(Vpk) Vacinst/{square root over (2)}) 33 217 450 .132 390.6 277 11
239 450 .044 430.2 304
[0069] Table 1 shows an example of identifying an AC mains
transient event by sensing the PFC bus voltage and sensing the PFC
switching on-time in order to compute an AC mains voltage swell of
304 V.sub.rms. The lighting system status apparatus 544 computes,
or calculates, this out of bounds anomaly and prioritizes this data
for notification and transmission to the data acquisition lighting
system controller 160.
[0070] With reference to secondary side anomalies, the power
monitor current sensing circuit 302 can detect an anomaly for a set
of light loads in a lighting zone. As an example, a lighting zone
may have a set of four (4) light loads 140 connected to four (4)
power channels 320 operating at 25 W each for a total power of 100
W. The set of power channels 320 is coupled to the power monitor
300 that should sense a nominal current value of 2.36 A based on a
42.4 V.sub.dc regulated output bus.
[0071] A rapid reduction in sensed current of 25% as seen by the
power monitor sensing circuit 302 can indicate a possible
disconnection or a failure of a light fixture in the lighting
zone.
[0072] In a further example, a combination of data from various
sense circuits or points can assist in determining what type of
anomaly or fault may have occurred. A connection or disconnection
of one or more light loads representing a change in output power
such as 25% results in a DC output bus 260 voltage transient
anomaly detected by sensing circuit 262. In the same time interval,
the power monitor 300 including the current sensing circuit 302 may
detect a step change in load current. Based on an analysis by the
lighting system status apparatus 544, the type of anomaly or fault
can be determined, in this case, a connection or disconnection of a
light load.
[0073] After an analysis of the sensed measurements or signals by
the lighting system apparatus 544, if an anomaly is not detected,
the data is stored in non-volatile memory 580 as a log file so that
it can be stored for later retrieval, if desired.
[0074] In a preferred embodiment, a snap shot data packet is stored
as a 64 byte entry and in one implementation, a 1 megabyte (MB)
memory space can store approximately 55 days of lighting system
data. The data acquisition lighting system controller 160 polls the
LED driver 100 for retrieval of all or part of the data log at
predetermined time internals.
[0075] It is understood that the size of a data packet in terms of
the number of bytes can be increased or decreased as the number of
samples and/or snap shot interval is varied.
[0076] A standards based lighting protocol may include but is not
limited to a protocol such as Remote Device Management (RDM) or
DALI (Digital Addressable Lighting Interface) or DALI-2 or any
variations of such protocols. The RDM protocol is defined in E1.20
Remote Device Management over DMX512 Networks. DALI-2 requirements
are defined in a group of standards based on IEC 62386 such as IEC
62386-102; General Requirements Control Gear, and IEC 62386-207;
Particular Requirements for Control Gear-LED Modules. A standards
based LAN (Local Area Network) protocol may include but is not
limited to an Ethernet protocol defined in a group of standards
based on IEEE802.3 or variations of such a protocol.
[0077] In one embodiment, transmission of data and notification of
anomalies by the communication interface 546 is implemented by a
lighting based protocol such as RDM or DALI 2. In another
embodiment, transmission of data and notification of anomalies by
the communication interface 546 is implemented by an Ethernet
protocol. The data acquisition lighting system controller 160 can
include an integrated Ethernet switch to connect multiple LED
drivers 100 to the LAN or the Ethernet switch may be an external
apparatus coupled to the data acquisition lighting system
controller 160.
[0078] Turning to FIG. 2a, a schematic diagram of a voltage sense
circuit or sense point for sensing an internal voltage is shown. In
the current embodiment, the sense circuit is implemented for the
voltage regulation of a DC bus as well as implemented as a sensing
circuit for detection of lighting system anomalies. As an example,
this voltage sensing circuit of FIG. 2a may represent sensing
circuit 206 within the primary side PFC power conversion stage 200
and/or the sensing circuit 262 associated with the secondary side
DC Output Bus 260 where DC voltage regulation is required. The
sensing circuit 206 or 262 includes a voltage divider network with
a pair of scaling resistances 600 and 602 connected to an ancillary
circuit 606. In one embodiment, the circuit 606 may include various
components such as, but not limited to, low pass filter RC
(resistor, capacitor) components, an OP amp buffer and/or
additional resistor divider components as needed to scale the
analog voltage to an appropriate level for the analog to digital
(A/D) conversion circuit 608 located in the primary or secondary
monitoring and fault detection apparatus. Also shown is the
feedback voltage control loop apparatus 604 implemented to regulate
the DC bus 610 to a required nominal level.
[0079] FIG. 2b is a schematic diagram of a current sense circuit or
sense point for the sensing of internal current at various points
within the LED driver 100 such as sense points 302 and 322C. The
sensing circuit of FIG. 2b senses a current level that passes
through the sensing circuit. The circuit includes a current
feedback control loop 620 that is connected to a resistive
component 622 that receives the current. The resistive component
622 is further connected to a filter/scale/buffer component 624 and
an A/D converter 626.
[0080] FIG. 3 is a block diagram showing an embodiment of a power
channel 320. In this figure, the power channel 320 is implemented
with a current source 324 and both a current sensing, or sense
circuit 322C and a voltage sensing, or sense circuit 322V. In this
embodiment, the voltage and current sense circuits 322C and 322V
assist to identify various anomalies on the secondary side of the
lighting system or LED driver 100 by measuring current and voltage
levels for processing by the secondary side monitoring circuit
542.
[0081] In one embodiment, the voltage sensing circuit 322V monitors
the output voltage across the cabling 144 supplying the voltage to
remotely connect light load 140 while the current sensing circuit
322C monitors the output current through the cabling 144 and the
light load 140.
[0082] Measured or sensed analog signal values from the current and
voltage sensing circuits are transmitted via data lines 400 to the
scaling, level shift, and buffer circuits 543 located in the
secondary side monitoring and fault detection apparatus 542. The
scaling, level shift and filtering circuits 543 adapt the analog
signals to suitable signals for the A/D conversion circuits 545. In
one embodiment, the conversion circuits have a sampling resolution
of 10 to 12 bits.
[0083] In one embodiment of operation, a shorted power channel
output or light load failure can be determined by sensing both the
voltage across the output power channel 320 and the current through
the light load 140. If the constant current source 324 is
configured to provide a 700 mA drive current and the output voltage
range of the power channel 320 is a predetermined range of 12 Vdc
to 40 Vdc, a shorted output would have the current sensing circuit
322C detect a drive current equal to or greater than 700 mA. At the
same time, the voltage sensing circuit 322V would detect a voltage
level of less than 12 Vdc. The combination of these two sensed
signals indicates a continuous current flow through a reduced
impedance which would be seen as an anomaly by the secondary side
monitoring and fault detection circuit 542 and the light system
apparatus 544.
[0084] In another example of an overload condition determination,
the rated load of a power channel is established at 40 Vdc at 700
mA representing a power rating of 28 watts. An overload condition
can be detected by a connection of a light load with a rating of 42
Vdc at 700 mA representing a power rating of 29.4 watts. The
combination of voltage and current sense point data in this
instance can be used by the secondary side monitoring circuit to
detect a power overload condition.
[0085] In both instances, the lighting system apparatus 544 as
shown in FIG. 1, based on an analysis of the sense point data or
measured signals, can determine when an anomaly has occurred on the
output, or secondary, side of the lighting system and prioritizes
the data and notification for transmission of such an event.
[0086] Turning to FIG. 4, an embodiment of apparatus for sensing
the on-time of a gate drive semiconductor switch is shown. In this
embodiment, the PFC power converter stage 200 includes a boost
converter switch mode topology 201 and a semiconductor switch 203
such as a MOSFET. The semiconductor switch 203 is operated by a
gate drive circuit 204 which is part of a PFC controller integrated
circuit (IC). In the current embodiment, the gate drive circuit 204
is connected to a Schmitt trigger 501 which is connected to a timer
502 located in the primary side monitoring and fault detection
apparatus 510. The timer 502 updates at a rate of 4.times.10.sup.6
times per second or in 250 ns (nanosecond) intervals based on a
Schmitt trigger threshold of 4 volts or greater.
[0087] By determining how far the timer has counted, the switch
on-time can be established. For example, a count of 10 would
determine a switch on-time of 2.5 microseconds. A count of 20 would
determine a switch on-time of 5 microseconds. It is understood that
the implementation of an on time counter coupled to a gate drive of
a semiconductor switch to determine duty cycle and associated input
or output voltages can be applied to other power conversion
topologies such as, but not limited to, a buck converter.
[0088] FIG. 5 is a table showing various primary side and secondary
side sensing circuits internal to an LED driver with associated
data collection possibilities. The sensor readings are analyzed by
the lighting system status apparatus to identify anomaly or fault
possibilities that have occurred within the lighting system.
[0089] An example of a fault condition that can be detected include
an interconnection between two power channels implemented with
constant current outputs. In this instance, a connection between
the positive output (+ve) of one channel to the negative output
(-ve) of another channel results in excessive current being
detected by a current sense point in one of the power channels.
[0090] FIG. 6 is a flow chart of a method of data acquisition for a
lighting system. In the current embodiment, the lighting system
includes an LED driver connected to the AC mains and to a set of
output power channels connected to a set of light fixture loads
such as schematically shown in FIG. 1.
[0091] The primary side and secondary side monitoring and fault
monitoring circuits receive measurements or data readings from the
primary and isolated secondary side sensing circuits collect data
readings from the various sensing circuits located within
components of the LED driver (610). The lighting system status
apparatus then filters and/or analyzes the received measurements or
data readings (620) over a predetermined period of time. The
analysis of the data may be completed over a predetermined period
of time and may include comparing sensor readings to predetermined
limits and/or calculated statistical parameters based in historical
data. In another embodiment, the data readings are filtered for
specific characteristics or predetermined criteria and then
processed after being filtered. The data readings are then stored
in nonvolatile memory (625) for subsequent retrieval.
[0092] The lighting system status apparatus then determines if an
anomaly or fault has occurred (630) based on an analysis of the
data. If it is determined that an anomaly or fault has occurred,
the data and/or notification of such an event are prioritized for
immediate transmission to the data acquisition lighting system
controller (640). In other words, a notification or indication of
the detection of the anomaly or fault is transmitted to the
lighting system controller.
[0093] If no anomaly or fault is detected or determined, the
received data readings are maintained in non-volatile memory. At a
predetermined time schedule or based on a request from data
acquisition lighting system controller, the stored data readings
are then transmitted in whole or in part from the memory to the
lighting system controller or another external component (660).
[0094] FIG. 8 is a block diagram of an alternate embodiment of an
LED driver with data acquisition capabilities. Although not all
components are shown, the data acquisition apparatus of FIG. 8 may
include the same components as the apparatus 500 of FIG. 1 such as
the sensing circuits. In the current embodiment, the LED driver 100
includes an auxiliary power source 220 implemented using a buck or
buck-boost converter topology. More specifically, such power
conversion topologies can include a forward converter or a flyback
topology configured to independently supply the required power and
voltage levels to the data acquisition apparatus 500.
[0095] In operation, the auxiliary power source 220 provides power
to the data acquisition apparatus 500 in the event of a component
failure of the LED driver 100 or power circuit. Alternatively, the
auxiliary power source 220 can continue to power the data
acquisition apparatus 500 in the event of a latch off anomaly or
fault experienced by the LED driver.
[0096] A latch off may occur as a result of the activation of
various internal protection circuits such as over voltage or over
current protection circuits due to an anomaly or internal fault.
For example, such activation can arise as a result of power quality
anomalies on the AC mains input 120 or overload events on the
output light load side 140 or as an internal component failure
within the LED driver 100.
[0097] The maintenance of power to the data acquisition apparatus
500 permits the sensing of a power circuit failure or a latch off
event to be communicated via the data acquisition apparatus 500 to
the data acquisition lighting system controller 160 even after the
fault or latch off has occurred.
[0098] FIG. 9 is a block diagram of an alternate embodiment of an
LED driver 100 with a visual display 700. The visual display 700
can include either an LED segment display, an LCD (liquid crystal
display) or an OLED (organic light emitting diode) display to
provide data and notifications of lighting system status. Based on
signal information transmitted by the data acquisition apparatus
500 to the display 700, the display can then provide information to
a user. The visual display 700 can also be prompted to query
various parameters via a set of rotary dials 710 with a decimal
range of 0-999 or alternatively via a key pad (not shown).
[0099] For example, the rotary dials can be set to a value or
decimal value of 909 which will display the DC output bus voltage.
The code 909 is transmitted to the processor that can then access a
look-up table to determine the information being request. Once the
processor determines the requested information, the information can
be retrieved and sent to the visual display for display. Similarly,
the rotary dials can be set to a value of 905 to display the
calculated output power at the output of the power monitor
apparatus based on the a voltage value measured by the sensing
circuit 262 of the DC output bus and the power monitor current
sensing circuit 302 as referenced in FIG. 1.
[0100] FIG. 10 is a table showing example parameters that can be
displayed on the visual display. In one embodiment, these symbols
may be used to indicate lighting system status. The table includes
parameters and error codes that can be measured internally within
the LED driver and displayed. The table also includes error codes
that can be generated and displayed to identify internal faults
within the LED driver.
[0101] Although the present disclosure has been illustrated and
described herein with reference to preferred embodiments and
specific examples thereof, it will be readily apparent to those of
ordinary skill in the art that other embodiments and examples may
perform similar functions and/or achieve like results. All such
equivalent embodiments and examples are within the spirit and scope
of the present disclosure.
[0102] In the preceding description, for purposes of explanation,
numerous details are set forth in order to provide a thorough
understanding of the embodiments. However, it will be apparent to
one skilled in the art that these specific details may not be
required. In other instances, well-known structures may be shown in
block diagram form in order not to obscure the understanding. For
example, specific details are not provided as to whether elements
of the embodiments described herein are implemented as a software
routine, hardware circuit, firmware, or a combination thereof.
[0103] Embodiments of the disclosure or components thereof can be
provided as or represented as a computer program product stored in
a machine-readable medium (also referred to as a computer-readable
medium, a processor-readable medium, or a computer usable medium
having a computer-readable program code embodied therein). The
machine-readable medium can be any suitable tangible,
non-transitory medium, including magnetic, optical, or electrical
storage medium including a diskette, compact disk read only memory
(CD-ROM), memory device (volatile or non-volatile), or similar
storage mechanism. The machine-readable medium can contain various
sets of instructions, code sequences, configuration information, or
other data, which, when executed, cause a processor or controller
to perform steps in a method according to an embodiment of the
disclosure. Those of ordinary skill in the art will appreciate that
other instructions and operations necessary to implement the
described implementations can also be stored on the
machine-readable medium. The instructions stored on the
machine-readable medium can be executed by a processor, controller
or other suitable processing device, and can interface with
circuitry to perform the described tasks.
* * * * *