U.S. patent application number 14/481081 was filed with the patent office on 2015-08-06 for method of determining circulation state of cooling water.
The applicant listed for this patent is Hyundai Motor Company. Invention is credited to Kang Sik Jeon, Dong Hun Lee.
Application Number | 20150219104 14/481081 |
Document ID | / |
Family ID | 53547124 |
Filed Date | 2015-08-06 |
United States Patent
Application |
20150219104 |
Kind Code |
A1 |
Lee; Dong Hun ; et
al. |
August 6, 2015 |
METHOD OF DETERMINING CIRCULATION STATE OF COOLING WATER
Abstract
A method of determining a state of cooling water is provided.
The method includes operating, by a controller, a driving motor of
a cooling water-circulating pump that is configured to circulate
cooling water at a fixed current, a fixed torque, or a fixed power.
In addition, the controller is configured to calculate an average
rotation speed of the driving motor for a preset first period of
time during the operation of the driving motor. Whether the
circulation state of the cooling water is normal is determined
based on an error between the calculated average rotation speed and
a preset reference rotation speed.
Inventors: |
Lee; Dong Hun; (Anyang,
KR) ; Jeon; Kang Sik; (Yongin-Gyeonggi-Do,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hyundai Motor Company |
Seoul |
|
KR |
|
|
Family ID: |
53547124 |
Appl. No.: |
14/481081 |
Filed: |
September 9, 2014 |
Current U.S.
Class: |
417/42 |
Current CPC
Class: |
F04D 15/0254 20130101;
F04D 15/0066 20130101; F04D 13/06 20130101; F04D 15/0077 20130101;
F04D 15/0236 20130101 |
International
Class: |
F04D 15/02 20060101
F04D015/02; F04D 13/06 20060101 F04D013/06; F04D 15/00 20060101
F04D015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 6, 2014 |
KR |
10-2014-0013723 |
Claims
1. A method of determining a circulation state of cooling water,
comprising: operating, by a controller, a driving motor of a
cooling water-circulating pump configured to circulate cooling
water at a fixed current, a fixed torque, or a fixed power;
calculating, by the controller, an average rotation speed of the
driving motor for a preset first period of time during the
operation of the driving motor; and determining, by the controller,
whether the circulation state of the cooling water is normal, based
on an error between the calculated average rotation speed and a
preset reference rotation speed.
2. The method according to claim 1, wherein the calculation of the
average rotation speed includes: calculating, by the controller, a
deviation in rotation speed of the driving motor for the preset
first period of time.
3. The method according to claim 2, wherein the determination of
the circulation state of the cooling water includes: determining,
by the controller, whether the circulation state of the cooling
water is normal by comparing a deviation in the calculated average
rotation speed and a preset reference deviation.
4. The method according to claim 1, wherein the preset reference
rotation speed is a rotation speed of the driving motor that
corresponds to the fixed current, the fixed torque, or the fixed
power.
5. A method of determining a circulation state of cooling water,
comprising: operating, by a controller, a driving motor disposed in
a pump for circulating a cooling water to adjust a rotation speed
of the driving motor to be substantially constant; and determining,
by the controller, whether a circulation state of the cooling water
is normal using a power or torque value of the driving motor
obtained after the rotation speed of the driving motor is adjusted
to be substantially constant and a reference power or torque value
during a normal state that corresponds to the substantially
constant rotation speed.
6. The method according to claim 5, wherein the power or torque
value of the driving motor, and the reference power or torque value
of the driving motor when the driving motor rotates at the rotation
speed are each obtained substantially constant using a current
command value transmitted to the driving motor and a current
command value during the normal state that corresponds to the
substantially constant rotation speed.
7. The method according to claim 6, wherein the determination of
the circulation state of the cooling water includes: calculating,
by the controller, an average value of the current command values
transmitted to the driving motor for a first period of time after
the rotation speed of the driving motor is adjusted to be
substantially constant; and determining, by the controller, whether
the circulation state of the cooling water is normal, based on an
error between the calculated average value and the current command
value during the normal state that corresponds to the substantially
constant rotation speed.
8. The method according to claim 7, wherein the determination of
the circulation state of the cooling water includes: normalizing,
by the controller, by dividing the calculated average value by the
current command value during the normal state that corresponds to
the substantially constant rotation speed.
9. The method according to claim 7, further comprising:
determining, by the controller, that the circulation state of the
cooling water is abnormal when a state when the error exceeds a
preset error reference value is maintained for a second period of
time.
10. The method according to claim 7, further comprising: enabling,
by the controller, a test mode when the error exceeds a preset
error reference value.
11. The method according to claim 10, further comprising in the
test mode: determining, by the controller, that the circulation
state of the cooling water is abnormal, when a state when an error
between the calculated average value and the current command value
used when the driving motor rotates at a maximum rotation speed in
the test mode exceeds the error reference value is maintained for a
preset second period of time.
12. The method according to claim 10, wherein the error reference
value varies according to the rotation speed of the driving
motor.
13. The method according to claim 10, wherein the driving motor is
maintained at a maximum rotation speed, when the test mode is
enabled.
14. The method according to claim 6, wherein the current command
value that corresponds to the rotation speed is obtained using a
preset current command map based on the rotation speed.
15. The method according to claim 6, wherein the determination of
the circulation state of the cooling water includes: calculating,
by the controller, a deviation or a variation value in the current
command value for the first period of time; and determining, by the
controller, whether the circulation state of the cooling water is
normal, based on a result of a comparison between the calculated
deviation or variation value and a preset reference value.
16. The method according to claim 15, further comprising:
determining, by the controller, that the circulation state of the
cooling water is abnormal, when a state where the calculated
deviation or variation value exceeds the preset reference value is
maintained for a second period of time.
17. The method according to claim 15, wherein a test mode is
enabled, when the calculated deviation or variation value exceeds
the preset reference value.
18. The method according to claim 17, wherein the driving motor is
maintained at a maximum rotation speed when the test mode is
enabled.
19. The method according to claim 6, wherein the determination of
the circulation state of the cooling water includes: integrating,
by the controller, an error between the current command value that
corresponds to the rotation speed and the current command value
transmitted to the driving motor; and determining, by the
controller, whether the circulation state of the cooling water is
normal, based on a result of a comparison between the value of the
integral operation and a preset reference value.
20. The method according to claim 19, further comprising:
normalizing, by the controller, by dividing the calculated average
value by the current command value during the normal state that
corresponds to the rotation speed.
21. The method according to claim 19, further comprising:
determining, by the controller, that the circulation state of the
cooling water is abnormal, when a state where the value of the
integral operation exceeds the preset reference value is maintained
for a second period of time.
22. The method according to claim 19, wherein a test mode is
enabled when the value of the integral operation exceeds the
reference value.
23. The method according to claim 22, wherein the driving motor is
maintained at a maximum rotation speed when the test mode is
enabled.
24. A method of determining a circulation state of cooling water,
comprising: maintaining, by the controller, a constant rotation
speed of a driving motor of a cooling water-circulating pump
configured to circulate cooling water; and enabling, by the
controller, a test mode when an error between a power or torque
value of the driving motor after the rotation speed is maintained
substantially constant and a reference power or torque value during
a normal state that corresponds to the rotation speed maintained
substantially constant is occurred.
25. The method according to claim 24, further comprising in the
test mode: determining, by the controller, whether the circulation
state of the cooling water is normal, in a state when the driving
motor rotates at a maximum rotation speed.
Description
CROSS-REFERENCE(S) TO RELATED ED APPLICATION
[0001] The present application claims priority of Korean Patent
Application Number 10-2014-0013723 filed on Feb. 6, 2014, the
entire contents of which application are incorporated herein for
all purposes by this reference.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to a method of determining a
circulation state of cooling water, and more particularly to a
method of determining a circulation state of cooling water from
torque, power, and rotation speed of a cooling water-circulating
pump.
[0004] 2. Description of the Related Art
[0005] A fuel cell system mounted within a fuel cell vehicle
includes a hydrogen supply mechanism that supplies hydrogen to a
fuel cell stack, an air supply mechanism that supplies air
containing oxygen serving as an oxidant necessary for
electrochemical reaction, to the fuel cell stack, the fuel cell
stack that produces electricity through the electrochemical
reaction between the supplied hydrogen and oxygen, and a
heat-and-water managing mechanism that eliminates heat generated by
the electrochemical reaction and manages the operation temperature
of the fuel cell stack.
[0006] The heat-and-water managing mechanism includes a pump
configured to circulate cooling water through the fuel cell stack,
a radiator configured to cool the cooling water discharged from the
fuel cell stack, and an ion filter configured to filter out ions
eluted from a cooling pipeline. The heat-and-water managing
mechanism is equipped with an atmospheric pressure cap at an upper
end thereof, an open-type reservoir, and a level sensor within the
reservoir. The reservoir should have a substantially small
packaging space in which the level sensor is installed. However, it
may be difficult to secure the packaging space. Furthermore,
although the packaging space is secured and the level sensor is
installed within the packaging space, the level sensor may not be
able to sense exhaustion of cooling water, indicating a normal
level for the cooling water although an insufficient amount of
cooling water is present when air is mixed with water in the
cooling water.
[0007] In a conventional technology, a shortage of cooling water is
detected by a level sensor installed within a reservoir or a
pressure sensor installed within a pipeline. However, this
conventional technology has the disadvantage that the level sensor
or pressure sensor may malfunction due to disturbance such as a
change in temperature of cooling water, a change in cooling loop
attributable to opening and closing of a cooling pipeline valve,
and vibration of a vehicle or equipment. In order to solve this
problem, a flow sensor has been installed in a cooling water
pipeline. However, in this solution also the flow sensor is
expensive and is difficult to install due to the additional
necessary piping for the installation of the flow sensor.
[0008] The foregoing is intended merely to aid in the understanding
of the background of the present invention, and is not intended to
mean that the present invention falls within the purview of the
related art that is already known to those skilled in the art.
SUMMARY
[0009] Accordingly, the present invention provides a method of
determining a circulation state of cooling water, which may detect
shortage and abnormal circulation of cooling water.
[0010] According to one aspect, a method of determining a
circulation state of cooling water may include: operating a driving
motor configured to drive a cooling water-circulating pump at a
fixed current, fixed torque, or fixed power; calculating an average
rotation speed of the driving motor for a first period of time
preset during the operation of the driving motor; and determining
whether the circulation state of the cooling water is normal (e.g.,
without error or with minimal error), from a calculated error
between the average rotation speed of the driving motor and a
preset reference rotation speed of the driving motor.
[0011] The calculation of the average rotation speed may include
calculating a deviation in a rotation speed of the driving motor
for the first period of time. The determination of the circulation
state of the cooling water may refer to a step of determining
whether the circulation step of the cooling water is normal by
comparing the calculated deviation in the rotation speed a preset
reference deviation. The reference rotation speed may be a rotation
speed of the driving motor which corresponds to the fixed current,
fixed torque, or fixed power.
[0012] According to another aspect, a method of determining a
circulation state of cooling water may include: operating a driving
motor disposed a pump for circulating a cooling water-circulating
to maintain a rotation speed of the driving motor for the cooling
water-circulating pump to be substantially constant; and
determining whether the circulation state of the cooling water is
normal using a power or torque value of the driving motor after the
rotation speed of the driving motor is maintained substantially
constant, and a reference power or torque value during a normal
state which corresponds to the rotation speed of the driving motor
maintained substantially constant.
[0013] The power or torque value of the driving motor, and the
power or torque value at the rotation speed may be each obtained
using a current command value transmitted to the driving motor and
a current command value during a normal state which corresponds to
the rotation speed which may be maintained substantially constant.
The determination of the circulation state of the cooling water may
include calculating an average value of the current command values
transmitted to the driving motor for the first period of time after
the rotation speed is maintained substantially constant, and
determining whether the circulation state of the cooling water is
normal, based on an error between the calculated average value and
the current command value during the normal state which corresponds
to the substantially constant rotation speed.
[0014] The method may further include a normalizing step of
dividing the calculated average value by the current command value
during the normal state which corresponds to the substantially
constant rotation speed. When a state where the error exceeds an
preset error reference value is maintained for a second period of
time, the circulation state of the cooling water may be determined
to be abnormal. When the error exceeds the error reference value,
the method may further include enabling a test mode. When a state
where an error between the calculated average value and a current
command value used when the driving motor rotates at a maximum
rotation speed exceeds the error reference value is maintained for
the second period of time in the test mode, the circulation state
of the cooling may be determined to be abnormal. The error
reverence value may vary according to the rotation speed of the
driving motor. The current command value that corresponds to the
rotation speed may be obtained using a current command map preset
according to rotation speeds. When the test mode is enabled, the
driving motor may be controlled to maintain the maximum rotation
speed.
[0015] The determination of the circulation state of the cooling
water may include calculating a deviation or a variation value in
current command value for the first period of time, and determining
whether the circulation state of the cooling water is normal, based
on a result of a comparison between the calculated deviation or
variation value and a preset reference variation value. When a
state where the deviation or variation value which is calculated
exceeds the preset reference variation value is maintained for the
second period of time, the circulation state of the cooling water
may be determined to be abnormal. When the deviation or variation
value which is calculated exceeds the preset reference variation
value, the method may include enabling a test mode. When the test
mode is enabled, the driving motor may be controlled to maintain a
maximum rotation speed.
[0016] The determination of the circulation state of the cooling
water may include integrating an error between a current command
value that corresponds to the rotation speed and a current command
value transmitted to the driving motor, and determining whether a
circulation state of the cooling water is normal, based on a result
of the comparison between a value of the integral operation and a
reference value.
[0017] The method may further include a normalization step of
dividing the calculated average value by the current command value
during the normal state which corresponds to the rotation speed.
When a state when the value of the integral operation exceeds the
preset reference value for the second period of time, the
circulation state of the cooling water may be determined to be
abnormal. When the value of the integral operation exceeds the
reference value, the method may further include enabling a test
mode. When the test mode is enabled, the driving motor may be
controlled to cause the driving motor to rotate at a maximum
rotation speed.
[0018] According to a further aspect, a method of determining a
circulation state of cooling water may include: operating a driving
motor of a pump configured to circulate cooling water to maintain a
rotation speed of the driving motor substantially constant; and
enabling a test mode when an error between a power or torque value
of the driving motor for a preset period of time after the rotation
speed becomes constant and a reference power or torque value during
a normal state which corresponds to the substantially constant
rotation speed is occurred. In the test mode, whether the
circulation state of the cooling water is normal (e.g., without
error or with minimal error) may be determined, in a state where
the maximum rotation speed of the driving motor may be
maintained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The above and other objects, features and other advantages
of the present invention will be more clearly understood from the
following detailed description when taken in conjunction with the
accompanying drawings, in which:
[0020] FIG. 1A is an exemplary graph showing relations between a
rotation speed of a driving motor and a difference in pressure
between an inlet and an outlet of a cooling water-circulating pump
according to an exemplary embodiment of the present invention;
[0021] FIG. 1B is an exemplary graph showing relations between a
rotation speed of a driving motor and a flow rate of cooling water
according to an exemplary embodiment of the present invention;
[0022] FIG. 1C is an exemplary graph showing relations between a
rotation speed of a driving motor and a power or torque of a
driving motor according to an exemplary embodiment of the present
invention;
[0023] FIG. 2 is an exemplary graph showing rotation speeds of a
driving motor in a normal circulation state and in an abnormal
circulation state of cooling water when the driving motor is
operated at a fixed current in a method of determining a
circulation state of cooling water according to one exemplary
embodiment of the present invention;
[0024] FIG. 3 is an exemplary graph showing an average value of
powers or torques of a driving motor for each circulation state of
cooling water in a method of determining a circulation state of
cooling water according to one exemplary embodiment of the present
invention;
[0025] FIG. 4 is an exemplary flowchart showing a method of
determining a circulation state of cooling water according to one
exemplary embodiment of the present invention; and
[0026] FIGS. 5 through 10 are exemplary flowcharts showing methods
of determining a circulation state of cooling water according to
other exemplary embodiments of the present invention.
DETAILED DESCRIPTION
[0027] It is understood that the term "vehicle" or "vehicular" or
other similar term as used herein is inclusive of motor vehicles in
general such as passenger automobiles including sports utility
vehicles (SUV), buses, trucks, various commercial vehicles,
watercraft including a variety of boats and ships, aircraft, and
the like, and includes hybrid vehicles, electric vehicles, plug-in
hybrid electric vehicles, hydrogen-powered vehicles and other
alternative fuel vehicles (e.g. fuels derived from resources other
than petroleum). As referred to herein, a hybrid vehicle is a
vehicle that has two or more sources of power, for example both
gasoline-powered and electric-powered vehicles.
[0028] Although exemplary embodiment is described as using a
plurality of units to perform the exemplary process, it is
understood that the exemplary processes may also be performed by
one or plurality of modules. Additionally, it is understood that
the term controller/control unit refers to a hardware device that
includes a memory and a processor. The memory is configured to
store the modules and the processor is specifically configured to
execute said modules to perform one or more processes which are
described further below.
[0029] Furthermore, control logic of the present invention may be
embodied as non-transitory computer readable media on a computer
readable medium containing executable program instructions executed
by a processor, controller/control unit or the like. Examples of
the computer readable mediums include, but are not limited to, ROM,
RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash
drives, smart cards and optical data storage devices. The computer
readable recording medium can also be distributed in network
coupled computer systems so that the computer readable media is
stored and executed in a distributed fashion, e.g., by a telematics
server or a Controller Area Network (CAN).
[0030] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof. As
used herein, the term "and/or" includes any and all combinations of
one or more of the associated listed items.
[0031] Specific structural and functional descriptions of exemplary
embodiments of the present invention disclosed herein are only for
illustrative purposes of the exemplary embodiments of the present
invention. The present invention may be embodied in many different
forms without departing from the spirit and significant
characteristics of the present invention. Therefore, the exemplary
embodiments of the present invention are disclosed only for
illustrative purposes and should not be construed as limiting the
present invention.
[0032] Reference will now be made in detail to various exemplary
embodiments of the present invention, specific examples of which
are illustrated in the accompanying drawings and described below,
since the exemplary embodiments of the present invention can be
variously modified in many different forms. While the present
invention will be described in conjunction with exemplary
embodiments thereof, it is to be understood that the present
description is not intended to limit the present invention to those
exemplary embodiments. On the contrary, the present invention is
intended to cover not only the exemplary embodiments, but also
various alternatives, modifications, equivalents and other
embodiments that may be included within the spirit and scope of the
present invention as defined by the appended claims.
[0033] It will be understood that, although the terms "first,"
"second," etc. may be used herein to describe various elements,
these elements should not be limited by these terms. These terms
are only used to distinguish one element from another element. For
instance, a first element discussed below could be termed a second
element without departing from the teachings of the present
invention. Similarly, the second element could also be termed the
first element.
[0034] It will be understood that when an element is referred to as
being "coupled" or "connected" to another element, it can be
directly coupled or connected to the other element or intervening
elements may be present therebetween. In contrast, it should be
understood that when an element is referred to as being "directly
coupled" or "directly connected" to another element, there are no
intervening elements present. Other expressions that explain the
relationship between elements, such as "between," "directly
between," "adjacent to," or "directly adjacent to," should be
construed in the same way.
[0035] Unless otherwise defined, all terms including technical and
scientific terms used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and the present
disclosure, and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0036] Hereinbelow, exemplary embodiments of the present invention
will be described in detail with reference to the accompanying
drawings Throughout the drawings, the same reference numerals will
refer to the same or like parts.
[0037] FIG. 1A is an exemplary graph showing relations between a
rotation speed of a driving motor and a difference in pressure
between an inlet and an outlet of a cooling water-circulating pump,
FIG. 1B is an exemplary graph showing relations between a rotation
speed of a driving motor and a flow rate of cooling water, and FIG.
1C is an exemplary graph showing relations between a rotation speed
of a driving motor and a power or torque of a driving motor.
[0038] With reference to FIGS. 1A to 1C, when cooling water
circulates normally in a cooling system, that is, without a
shortage, the difference in pressure between the inlet and the
outlet of the cooling water-circulating pump and the flow rate of
the cooling water are within normal ranges (e.g., predetermined
ranges). In particular, the torque required to drive the cooling
water circulating pump at a substantially constant speed may also
be within a predetermined range indicating a normal state. However,
when the cooling water does not circulate normally, the flow rate
of the cooling water and the difference in pressure may be beyond
the normal ranges, and the torque or power of the driving motor may
be beyond (e.g., out of) the predetermined range. In particular,
the operation speed of the cooling water-circulating pump may not
be maintained at the target value and may fluctuate based on the
load of the cooling water-circulating pump.
[0039] FIG. 2 is an exemplary graph showing rotation speeds of a
driving motor in a normal circulation state and in an abnormal
circulation state of cooling water when the driving motor is
operated at a fixed current in a method of determining a
circulation state of cooling water according to one exemplary
embodiment of the present invention. With reference to FIG. 2, when
the driving motor is operated at a fixed current and when the power
or torque of the driving motor is constant with time, the rotation
speed of the driving motor may be substantially constant when the
circulation state of the cooling is normal. The rotation speed of
the driving motor may fluctuate when the circulation state of the
cooling is abnormal, i.e. the shortage of cooling water occurs or
the load changes due to clogging of a pipeline, for example,
occurs.
[0040] More specifically, when the power or torque of the driving
motor is substantially constant and when the circulation state of
cooling water is abnormal an in sufficient amount of the cooling
water may be available since the load of the cooling
water-circulating pump (or driving motor) may decrease due to
bubbles (e.g., air bubbles) in cooling water pipelines, an average
rotation speed of the driving motor may increase, compared to a
normal circulation state. In particular, when bubbles are
introduced into the cooling water circulating-pump, the rotation
speed of the driving motor may fluctuate significantly due to a
sudden change in the load. When the amount of cooling water is
insufficient due to a leakage of the cooling water, bubbles may be
continuously introduced into the cooling water-circulating pump,
causing continuous fluctuations in the rotation speed of the
driving motor, or water may not be discharged properly, increasing
the rotation speed of the driving motor, compared to the normal
circulation state.
[0041] When foreign matters or impurities circulate along with the
cooling water through the cooling water pipeline, the load of the
cooling water-circulating pump may change or the rotation speed of
the driving motor may fluctuate, similar to when bubbles are
introduced into the cooling water circulating pump. Furthermore,
when the cooling water pipeline is clogged by foreign matters or
physically deformed portions of the cooling water pipeline, the
load of the cooling water-circulating pump may decrease
significantly and the rotation speed of the driving motor may be
increased significantly, compared to the normal circulation
state.
[0042] FIG. 3 is an exemplary graph showing an average value of the
power or torque of a driving motor for each circulation state of
cooling water in the method of determining the circulation state of
cooling water according to one exemplary embodiment of the present
invention. FIG. 3 shows a comparison between data of the power or
torque of a driving motor when the amount of cooling water is
normal (e.g., no insufficient) and data of the power or torque of a
driving motor when the amount of cooling water is abnormal (e.g.,
insufficient). When the amount of cooling water is insufficient,
the power or torque of a driving motor may be caused to fluctuate.
FIG. 3 shows average values of the fluctuating powers and torques.
When the amount of cooling water is insufficient, the average value
of the powers of a driving motor decreases and a deviation from the
average value increases.
[0043] There are various methods of obtaining the power or torque
of a driving motor. The methods include a method of measuring a
single-phase (DC) current and voltage, a method of measuring a
three-phase current and voltage, a method of using a torque sensor,
and a method of using a preset torque map according to a rotation
speed and an input voltage after measuring a three-phase current. A
current command is proportional to the torque of a driving motor.
Accordingly, it may be possible to calculate the torque based on a
value of the three-phase current (e.g., a vector sum of three
phases of currents) confirmed using the current command or measured
by a current sensor.
[0044] FIG. 4 is an exemplary flowchart showing a method of
determining a circulation state of cooling water according to one
exemplary embodiment of the present invention. First, a cooling
water-circulating pump, i.e., a cooling water driving motor may be
operated by a controller at a substantially fixed current (Step
S401). While the cooling water driving motor is operated at the
fixed current, an average rotation speed Rpm_mean or an average
rotation deviation Delta_Rpm for a first period of time T1, which
may be preset, may be calculated by the controller (Step S403).
After a predetermined period of time Time_1+.DELTA.T passes (Step
S405), the controller may be configured to determine whether a
predetermined elapsed time Time_1 greater than the first period of
time T1 has elapsed (Step S407). The purpose of this step is to
determine a circulation state of cooling water after the average
rotation speed Rpm_mean and the average rotation speed deviation
Delta_Rpm for the first period of time T1 may be calculated.
[0045] In response to determining that the first period of time T1
has elapsed; the controller may be configured to determine whether
the rotation speed of a driving motor is normal (e.g., within a
predetermined range), compared to a preset reference rotation (Step
S411). The reference rotation speed may be set in advance to a
rotation speed of a driving motor detected when the driving motor
operates at the substantially fixed current, or calculated from a
normal-state rotation speed Rpm_Normal of the cooling
water-circulating pump when the driving motor operates at the
substantially fixed current (Step S409). The controller may further
be configured to determine whether the rotation speed of the
driving motor is normal or abnormal, based on an error between the
calculated average rotation speed Rpm_mean and the calculated
normal-state rotation speed Rpm_Normal at the fixed current, or an
error between the rotation speed deviation Delta_Rpm for the first
period of time T1 and a preset reference deviation .epsilon.. In
particular, when determining whether the circulation state of the
cooling water is normal, when the error between the calculated
average rotation speed Rpm_mean and the normal-state rotation speed
Rpm_Normal at the fixed current is greater than a preset error
reference value .beta., or when the rotation speed deviation
Delta_Rpm for the first period of time T1 is greater than the
reference deviation .epsilon. is maintained for a second period of
time T2 which may be preset (Step S413 and Step S415), the
controller may be configured to determine that the circulation
state of the cooling water is abnormal.
[0046] When the first period of time T1 or the second period of
time T2 which may be preset has not elapsed, when the error between
the calculated average rotation speed Rpm_mean and the normal state
rotation speed Rpm_Normal at the fixed current is less than the
error reference value .beta., or when the rotation speed deviation
Delta_Rpm for the first period of time T1 is less than the
reference deviation .epsilon., the process may restart with Step
401. Subsequently, Step S401 in which the driving motor is operated
at the fixed current may be repeatedly performed. To calculate the
rotation speed deviation Delta_Rpm for the first period of time T1,
an average value of absolute errors, a standard deviation, or a
dispersion in the rotation speed for a preset period of time may be
used. Furthermore, either one or both of the average rotation speed
and the rotation speed deviation may be used to determine whether
the circulation speed of the cooling water is normal.
[0047] FIGS. 5 to 8 are exemplary flowcharts showing methods of
determining a circulation state of cooling water according to other
exemplary embodiments of the present invention. With reference to
FIGS. 5 to 7, the controller may be configured to determine whether
there is a change in speed command (Step S501, S601, and S701). The
speed command may be a control command value regarding the rotation
speed of a driving motor. These steps may be performed since a
current command value may be changed to increase or decrease the
rotation speed of a driving motor when the speed command is
changed. To improve the accuracy of the current command value, the
process determining a circulation state of cooling water may be
performed after the rotation speed is maintained to be
substantially constant.
[0048] After the rotation speed is maintained to be substantially
constant, the controller may be configured to determine whether the
circulation state of the cooling water is normal, from the current
command value transmitted to the cooling water driving motor for a
preset period of time and the current command value that
corresponds to the rotation speed maintained for a preset period of
time. Particularly, with reference to FIG. 5, after the constant
rotation speed of a driving motor is maintained, an average value
Iqcmd_mean of the current command values transmitted to the driving
motor for a first period of time T1 may be calculated in Step S505.
Next, the controller may be configured to determine whether the
average value Iqcmd_mean of the current command values for the
first period of time T1 is calculated normally, after a
predetermined period of time .DELTA.T has elapsed since a first
elapsed time Time_1 passed, by comparing the first elapsed time
Time_1 and the first period of time T1 (Step S507 and S509). When
the first period of time T1 is less than the first elapsed time
Time_1, the driving motor may be operated to adjust the rotation
speed of the driving motor to be substantially constant (Step
S501).
[0049] When the driving motor is not maintained at the constant
rotation speed, the first elapsed time Time_1 may be reset (Step
S503), and then the driving motor may be operated to adjust the
rotation speed to be substantially constant (Step S501). After the
rotation speed of the driving motor is adjusted to be substantially
constant, the current command value Iqnormal that corresponds to
the constant rotation speed may be calculated (Step S511). The
current command value Iqnormal that corresponds to the constant
rotation speed may be obtained using a current command map based on
the rotation speed. The current command value Iqnormal that
corresponds to the constant rotation speed may be a current command
value in a normal state at a present rotation speed of a cooling
water-circulating pump. The current command map may be a map in
which normal current command values are mapped with rotation speeds
of data obtained from experiments when a cooling water-circulating
pump operates normally or rotation speeds of data obtained through
calculations.
[0050] When an error between the calculated average value and a
normal current command value that corresponds to a rotation speed
is equal to or greater than a preset error reference value .beta.
(Step S515) and is maintained for a second period of time T2 (Step
S517 and Step S519), that controller may be configured to determine
that the circulation state of the cooling water is abnormal.
Additionally, when the error between the calculated average value
and the normal current command value that corresponds to the
rotation speed is less than the error reference value .beta., the
second period of time T2 may be reset and the cooling water driving
motor may be rotated at a new substantially constant rotation
speed. When a normalized current command value Iqcmd_Nom obtained
by dividing the current command value Iqcmd by the normal current
command value Iqnormal at the present rotation speed and
normalizing the result of the division is used, the speed command
value may be continuously changed. Accordingly, it may be possible
to determine whether the circulation state of the cooling water is
normal even within a period of time during which the rotation speed
changes.
[0051] With reference to FIG. 6, a deviation Iqcmd_sd or a
variation value in the current command value Iqcmd for the first
period of time T1 after the rotation speed of the driving motor is
adjusted to be substantially constant may be calculated (Step
S605). Further, the controller may be configured to determine
whether the deviation Iqcmd_sd or the variation value for the first
period of time T1 is accurately obtained (Step S607 and Step S609),
and the calculated deviation Iqcmd_sd or variation value may be
compared with a preset reference value .epsilon. (Step S611). When
the deviation Iqcmd_sd or variation value calculated exceeds the
preset reference value .epsilon., and when such a state is
maintained for a second period of time T2 (Step S615 and Step
S617), the controller may be configured to determine that the
circulation state of the cooling water is abnormal. A description
regarding the same process as in FIG. 5 will not be repeated. The
processing of FIG. 6 differs from the processing of FIG. 5 in that
a standard deviation may be calculated instead of the average
value.
[0052] With reference to FIG. 7, after the rotation speed of the
driving motor is adjusted to be substantially constant and the
substantially constant rotation speed may be maintained, a normal
state current command value Iqnormal at the maintained constant
rotation speed may be calculated (Step S705). Absolute values of
errors between the current command values Iqcmd transmitted to the
cooling water driving motor for the first period of time T1 and the
normal state current command value Iqnormal may be integrated (Step
S707). Further, the controller may be configured to determine
whether the value of the integral operation for the first period of
time T1 is accurate (Step S709 and Step S711). The value of the
integral operation of the absolute values for the first period of
time T1, and a preset reference value k may be compared (Step
S713). When a state when the value of the integral operation
exceeds the preset reference value k is continuously maintained for
the second period of time T2 (Step S717 and Step S719), the
controller may be configured to determine that the circulation
state of the cooling water is abnormal.
[0053] When the normalized current command value Iqcmd_Nom obtained
by dividing the current command value Iqcmd by the normal current
command value at the rotation speed measured at a present time and
by normalizing the result of the division is used, the speed
command value may be continuously changed. Accordingly, it may be
possible to determine whether the circulation state of the cooling
water is normal even within a period of time during which the
rotation speed changes.
[0054] FIGS. 8 to 10 are exemplary flowcharts showing methods of
determining a circulation state of cooling water according to other
exemplary embodiments of the present invention. With reference to
FIGS. 8 to 10, Steps S801 to S811, S901 to S909, and S1001 to S1011
correspond to Steps S501 to S511 in FIG. 5, Steps S601 to S609 in
FIG. 6, and Steps S701 to S711 in FIG. 7, respectively, a
description thereof is omitted.
[0055] With reference to FIG. 8, an absolute value of an error
between a calculated average value Iqcmd_means and a normal current
command value Iqnormal that corresponds to a rotation speed may be
compared with a preset error reference value .beta. (Step S813).
When the absolute value of the error between the calculated average
value Iqcmd_means and the normal current command value Iqnormal
that corresponds to the rotation speed exceeds the error reference
value .beta., the controller may be configured to determine whether
a test mode has been activated (i.e. Test flag=TRUE) (Step S815).
Further, when the absolute value of the error between the
calculated average value Iqcmd_means and the normal current command
value Iqnormal that corresponds to the rotation speed is less than
the error reference value .beta., mode switching to a test mode may
not be performed (Step S817, Test flag=FALSE), and a predetermined
constant speed command may be maintained.
[0056] In response to determining that the test mode is not
activated in Step S815, the test mode may be set (Test flag=TRUE),
and the driving motor of the cooling water-circulating pump may be
rotated at a maximum rotation speed (Step S823). It may be possible
to more accurately obtain an error in current when the driving
motor of the cooling water-circulating pump rotates at the maximum
rotation speed. In other words, when the circulation of the cooling
water is abnormal at the maximum rotation speed of the driving
motor, an error in the power of the driving motor may have a
largest value. Additionally, the rotation speed of the driving
motor may be set to a value obtained through experiment and at
which the abnormal circulation of the cooling water may be the most
easily determined. Besides the operation of the driving motor at
the maximum rotation speed, the error in current may also be
determined using a repetitive alternate operation at a maximum
rotation speed and a minimum rotation speed, a ramp
acceleration/deceleration operation, a stepwise
acceleration/deceleration operation.
[0057] When the test mode is set and when the driving motor of the
cooling water-circulating pump rotates at a constant maximum
rotation speed, the average value Iqcmd_means of the current
command values transmitted to the driving motor for a first period
of time T1 may be calculated again (Step S805). The controller may
be configured to determine whether the average value of the current
command values for the first period of time T1 is calculated
normally, after a predetermined period of time has passed since a
first elapsed time time1 elapsed, by comparing the first elapsed
time Time_1 and the first period of time T1 (Step S807, Step S809).
When the first period of time T1 is less than the first elapsed
time Time_1, the driving motor may be operated to adjust the
rotation speed to be substantially constant (Step S801). When a
substantially constant rotation speed is not maintained, the first
elapsed time Time_1 may be reset (Step S803), and the driving motor
may be operated to maintain a substantially constant rotation speed
(Step S801).
[0058] Furthermore, a current command value Iqnormal that
corresponds to the maximum rotation speed may be calculated (Step
S811). The current command value Iqnormal that corresponds to a
rotation speed may be obtained using a current command map based on
the rotation speed. The current command value Iqnormal that
corresponds to a rotation speed may be a substantially current
command value in a normal state of the circulation of the cooling
water at the rotation speed of the driving motor of the cooling
water-circulating pump at a present time. The current command map
may be a map in which normal current command values are mapped with
rotation speeds obtained through experiments in which a cooling
water-circulating pump operates normally or rotation speeds of data
obtained through calculations.
[0059] An absolute value of an error between the calculated average
value Iqcmd_means and the normal current command value Iqnormal
that corresponds to the rotation speed, and a preset error
reference value .beta. which may be compared (Step S813). When the
absolute value of the error between the calculated average value
Iqcmd_means and the normal current command value Iqnormal that
corresponds to the rotation speed exceeds the error reference value
.beta., the controller may be configured to determine whether a
test mode is activated (Test flag=TRUE) (Step S815). Since the test
mode may be set in Step S823, the controller may be configured to
determine whether a state when the absolute value of the error
between the calculated average value Iqcmd_means and the normal
current command value Iqnormal that corresponds to the rotation
speed exceeds the error reference value .beta. is maintained for a
preset second period of time T2. When the state when the absolute
value of the error between the calculated average value Iqcmd_means
and the normal current command value Iqnormal that corresponds to
the rotation speed exceeds the error reference value .beta. is
maintained for the second period of time T2, the controller may be
configured to determine that the circulation state of the cooling
water is abnormal.
[0060] The processing of FIG. 9 differs from the processing of FIG.
8 in that a standard deviation may be calculated instead of the
average value of the current command value for the first period of
time T1. Accordingly, whether to switch to the test mode may not be
determined based on a determination on whether the absolute value
of the error between the calculated average value Iqcmd_means and
the normal current command value Iqnormal that corresponds to a
rotation speed exceeds the error reference value .beta., but may be
determined based on a determination on whether the standard
deviation Iqcmd_sd exceeds a preset deviation value .epsilon..
[0061] When the calculated standard deviation exceeds the preset
deviation value .epsilon., the controller may be configured to
determine that the test mode is activated (Test flag=TRUE) (Step
S915). In addition, when the calculated standard deviation is equal
to or less than the preset deviation value .epsilon., switching to
the test mode may not be performed (Step S917, Test flag=FALSE),
and a constant speed command may be maintained (Step S901).
[0062] In response to determining that the test mode is not
activated in Step S915, the test mode may be set (Test flag=TRUE),
and the driving motor of the cooling water-circulating pump may be
operated at a maximum rotation speed in Step S923. It may be
possible to more accurately determine the error in current when the
driving motor of the cooling water-circulating pump rotates at the
maximum rotation speed. In other words, when an abnormal
circulation of the cooling water occurs at the maximum rotation
speed, the error in the power of the driving motor may become a
maximum. Additionally, the rotation speed of the driving motor may
be set to a value obtained through experiment and at which the
abnormal circulation of the cooling water may be the most easily
detected. The error in current may also be obtained using a
repetitive alternate operation at a maximum rotation speed and at a
minimum rotation speed, a lamp acceleration/deceleration operation,
or a stepwise acceleration/deceleration operation.
[0063] When the test mode is set and when the driving motor of the
cooling water-circulating pump rotates at the maximum rotation
speed, a standard deviation Iqcmd_sd of the current command values
Iqcmd transmitted to the driving motor of the cooling
water-circulating pump for the first period of time T1 may be
calculated again in Step S905. Further, the controller may be
configured to determine whether the standard deviation Iqcmd_sd of
the current command values for the first period of time T1 is
accurately calculated by comparing a first elapsed time Time_1 and
the first period of time T1 after a predetermined period of time
.DELTA.T has elapsed since the first elapsed time Time_1 elapsed
(Step S907, Step S909). When the preset first period of time T1 is
less than the first elapsed time Time_1, the driving motor may be
operated to adjust the rotation speed of the driving motor to be
substantially constant (Step S901). Further, when the rotation
speed of the driving motor is not constant, the first elapsed time
may be reset (Step S903), and the driving motor may be operated to
adjust the rotation speed of the driving motor to be substantially
constant (Step S901).
[0064] Subsequently, the recalculated standard deviation may be
compared with the preset deviation value .epsilon. (Step S911).
When the calculated standard deviation exceeds the preset deviation
value .epsilon., the controller may be configured to determine
whether the test mode is activated (e.g., set) (Test flag=TRUE) or
not (Step S913). Since the test mode may be set in Step S921, when
the state when the calculated deviation exceeds the preset
deviation value .epsilon. may be maintained for a second period of
time T2 (Step S917, Step S919), the controller may be configured to
determine that the circulation state of the cooling water is
abnormal.
[0065] With reference to FIG. 10, absolute values of errors between
the current command values Iqcmd transmitted to the driving motor
of the cooling water-circulating pump for the first period of time
T1 and the normal state current command value Iqnormal may be
integrated, and the value of the integral operation may be compared
with a preset reference value k (Step S1013). When the value of the
integral operation of the absolute values of the errors for the
first period of time exceeds the reference value k, the controller
may be configured to determine whether the test mode is activated
(e.g., set) (Test flag=TRUE) (Step S1015). In addition, when the
value of the integral operation of the absolute values of the
errors for the first period of time T1 is equal to or less than the
reference value k, switching to the test mode may not be performed
(S1017, Test flag=FALSE), and a substantially constant speed
command may be maintained again (Step S1001).
[0066] In response to determining that the test mode is not
activated in Step S1015, the test mode may be set (Test flag=TRUE),
and the driving motor of the cooling water-circulating pump may be
operated at the maximum rotation speed (Step S1023). It may be
possible to more accurately determine the error in current when the
driving motor of the cooling water-circulating pump operates at the
maximum rotation speed. In other words, when the abnormal
circulation of the cooling water occurs at the maximum rotation
speed, the error in the power of the driving motor may become a
maximum. Additionally, the rotation speed of the driving motor may
be a value obtained through experiment and at which the abnormal
circulation of the cooling water may be the most easily determined.
The error in current may also be obtained using a repetitive
alternate operation at a maximum rotation speed and a minimum
rotation speed, a lamp acceleration/deceleration operation, or a
stepwise acceleration/deceleration operation.
[0067] When the test mode is set and when the driving motor of the
cooling water-circulating pump rotates at a constant maximum
rotation speed, a normal state current command value Iqnormal at
the maximum rotation speed may be calculated again (Step S1005).
Further, absolute values of errors between current command values
Iqcmd transmitted to the driving motor for the first period of time
T1 and the normal state current command value Iqnormal may be
integrated (Step S1007). The controller may be configured to
determine whether the value of the integral operation for the first
period of time T1 is accurately calculated by comparing the first
elapsed time Time_1 and the preset first period of time T1 (Step
S1009, Step S1011), after a predetermined period of time .DELTA.T
has elapsed since the first elapsed time Time_1 elapsed. When the
preset first period of time T1 is less than the first elapsed time
Time_1, the driving motor may be operated to adjust the rotation
speed of the driving motor to be substantially constant again (Step
S1001). In addition, when the rotation speed of the driving motor
is not substantially constant, the first elapsed time may be reset
(Step S803), and the driving motor may be maintained at a constant
maximum rotation speed again (Step S801).
[0068] Furthermore, the absolute values of errors between the
current command values Iqcmd transmitted to the driving motor of a
cooling water-circulating pump for the first period of time T1 and
the normal state current command value Iqnormal may be integrated,
and the value of the integral operation may be compared with the
preset reference value k (Step S1013). When the value of the
integral operation of the absolute values of the errors for the
first period of time T1 exceeds the preset reference value k, the
controller may be configured to determine whether a test mode is
set or activated (Test flag=TRUE) (Step S1015). Since the test mode
may be set in Step S1023, when the state where the value of the
integral operation exceeds the reference value k is maintained for
the second period of time T2 (Step S1019, Step S1021), the
controller may be configured to determine that the circulation
state of the cooling water is abnormal.
[0069] Although exemplary embodiments of the present invention have
been described for illustrative purposes, those skilled in the art
will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying
claims.
* * * * *