U.S. patent application number 15/091342 was filed with the patent office on 2016-07-28 for power conversion apparatus and controlling method thereof.
The applicant listed for this patent is DELTA ELECTRONICS, INC.. Invention is credited to Cheng-Chieh CHAN, Chih-Hung HSIAO, Yun-Chi HUNG, Jo-Fang WEI.
Application Number | 20160216724 15/091342 |
Document ID | / |
Family ID | 49913442 |
Filed Date | 2016-07-28 |
United States Patent
Application |
20160216724 |
Kind Code |
A1 |
HSIAO; Chih-Hung ; et
al. |
July 28, 2016 |
POWER CONVERSION APPARATUS AND CONTROLLING METHOD THEREOF
Abstract
A power conversion apparatus and a controlling method thereof
are disclosed. The power conversion apparatus is applied with a
power generation apparatus, which outputs a first signal. The power
conversion apparatus includes a conversion-sensing circuit, a
control signal generating circuit and a switching circuit. The
conversion-sensing circuit converts the first signal into a second
signal, and senses at least a voltage waveform change of the second
signal to generate a time interval. The control signal generating
circuit is electrically connected with the conversion-sensing
circuit and outputs a control signal according to the time
interval. The switching circuit is electrically connected with the
power generation apparatus and the control signal generating
circuit, and has a plurality switching elements. The switching
circuit receives the first signal and conducts one of the switching
elements according to the control signal so as to convert the first
signal and output an output signal.
Inventors: |
HSIAO; Chih-Hung; (Taoyuan
City, TW) ; CHAN; Cheng-Chieh; (Taoyuan City, TW)
; WEI; Jo-Fang; (Taoyuan City, TW) ; HUNG;
Yun-Chi; (Taoyuan City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DELTA ELECTRONICS, INC. |
Taoyuan City |
|
TW |
|
|
Family ID: |
49913442 |
Appl. No.: |
15/091342 |
Filed: |
April 5, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13729651 |
Dec 28, 2012 |
9348353 |
|
|
15091342 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02J 1/102 20130101;
H02M 5/4585 20130101; H02M 7/219 20130101; G05F 5/00 20130101; H02M
7/797 20130101; H02J 15/00 20130101 |
International
Class: |
G05F 5/00 20060101
G05F005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 12, 2012 |
TW |
101125018 |
Claims
1. A power conversion apparatus applied with a power generation
apparatus, the power conversion apparatus comprising: a control
signal generating circuit, which is electrically connected with the
power generation apparatus and outputs a control signal according
to a first signal generated by the power generation apparatus; and
a brake energy recovery circuit electrically connected with the
power generation apparatus and the control signal generating
circuit, wherein the control signal controls the brake energy
recovery circuit to store energy generated when the power
generation apparatus brakes, and controls the brake energy recovery
circuit to release the stored electric power to the power
generation apparatus.
2. The power conversion apparatus according to claim 1, wherein the
brake energy recovery circuit has a switch unit, a first energy
storage element and a second energy storage element, the switch
unit is electrically connected with a first terminal of the first
energy storage element, and a second terminal of the first energy
storage element is electrically connected with a first terminal of
the second energy storage element.
3. The power conversion apparatus according to claim 1, further
comprising: a conversion-sensing circuit electrically connected
with the power generation apparatus and the control signal
generating circuit, wherein the conversion-sensing circuit converts
the first signal into a second signal, and the control signal
generating circuit outputs a control signal according to the second
signal.
4. The power conversion apparatus according to claim 3, wherein the
conversion-sensing circuit senses at least one voltage waveform
change of the second signal to generate a time interval.
5. The power conversion apparatus according to claim 4, wherein the
control signal generating circuit outputs the control signal
according to the time interval.
6. The power conversion apparatus according to claim 3, further
comprising: a switching circuit, which is electrically connected
with the brake energy recovery circuit, the power generation
apparatus and the control signal generating circuit, and has a
plurality of switching elements, wherein the switching circuit
receives the first signal and turns on one of the switching
elements according to the control signal so as to convert the first
signal and output an output signal.
7. The power conversion apparatus according to claim 6, further
comprising: a first energy storage unit electrically connected with
the power generation apparatus and the switching circuit, wherein
the first energy storage unit stores and releases electric power
generated by the power generation apparatus according to turn-on
and turn-off of the switching elements, respectively; and a second
energy storage unit, which is electrically connected with the brake
energy recovery circuit and stores electric power of the output
signal.
8. The power conversion apparatus according to claim 7, further
comprising: a filter unit, which is electrically connected with the
power generation apparatus and the first energy storage unit, and
stabilizes a voltage signal inputted to and outputted from the
power generation apparatus.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional of co-pending application
Ser. No. 13/729,651 filed on Dec. 28, 2012, which claims priority
under 35 U.S.C. .sctn.119(a) on Patent Application No(s). 101125018
filed in Taiwan, Republic of China on Jul. 12, 2012, the entire
contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] The invention relates to a conversion apparatus and a
controlling method thereof, and in particular, to a power
conversion apparatus and a controlling method thereof.
[0004] 2. Related Art
[0005] Recently, due to the rise of the environmental awareness and
the gradual depletion of the fossil energy (e.g., petroleum and
coal), countries around the world become aware of the importance of
the development of the new type energy. The wind power is the
inexhaustible energy without the doubt of energy depletion and can
also avoid the problem of the energy monopoly. Thus, the countries
around the world also actively develop the wind power generation
system to expect to reduce the dependence on the fossil energy by
increasing the utilization of the wind power.
[0006] The wind power generation system needs to convert the
electric power, generated from the wind power generator
(hereinafter referred to as a wind generator) via an electric power
conversion apparatus. In addition to saving or supplying the
converted electric power to the load, the converted electric power
may also be connected to the power supply grid in parallel. The
architectures of the conventional electric power conversion
apparatus may be substantially classified into a passive
architecture and an active architecture.
[0007] In the passive architecture, a passive full-bridge rectifier
converts the three-phase power, outputted from the wind generator,
into the single-phase power, and then achieves the objects of
energy conversion through the operations of an inductor and a
switch. Because the use of only a single switch can achieve the
energy conversion, the energy loss of the apparatus is extremely
small. When being applied to the low wind speed or the low power
wind generator, the conversion efficiency of the apparatus is
relatively high. However, the passive architecture cannot actively
control and adjust the power factor, and the loss thereof also
proportionally rises with the increases of the power and the
current. When being applied to the middle or high wind speed or the
high power wind generator, the power loss of the apparatus upon
conversion is relatively high.
[0008] In the active architecture, six active switches and three
inductors are utilized, and the instantaneous rotating speed is
obtained through a rotor position detector (e.g., an encoder)
disposed on the generator to control the instantaneous rotating
speed, so that the power conversion apparatus can complete the
electric power conversion. Because the active architecture can be
synchronously changed with the change of the three-phase AC power
outputted form the wind generator and can achieve the full power
energy conversion, the conversion efficiency thereof is relatively
high and the energy loss thereof is relatively low when being
applied to the high wind speed or the high power wind generator.
However, the active architecture needs to drive six active switches
to operate concurrently and needs to supply the power to the
position detector disposed on the generator to have the long
distance line loss, so that the power loss is much larger than that
of the passive system. Thus, the active architecture is not
advantageous to the wind energy conversion for the low wind speed
or the low power wind generator.
[0009] Therefore, it is an important subject to provide a power
conversion apparatus, having full power and high efficiency energy
conversion and lower power loss, and a controlling method
thereof.
SUMMARY OF THE INVENTION
[0010] In view of the foregoing subject, an objective of the
invention is to provide a power conversion apparatus, having full
power and high efficiency energy conversion and lower power loss,
and a controlling method thereof.
[0011] To achieve the above objective, the present invention
discloses a power conversion apparatus applied with a power
generation apparatus, which outputs a first signal. The power
conversion apparatus includes a conversion-sensing circuit, a
control signal generating circuit, and a switching circuit. The
conversion-sensing circuit converts the first signal into a second
signal and senses at least one voltage waveform change of the
second signal to generate a time interval. The control signal
generating circuit is electrically connected with the
conversion-sensing circuit and outputs a control signal according
to the time interval. The switching circuit is electrically
connected with the power generation apparatus and the control
signal generating circuit, and has a plurality of switching
elements. The switching circuit receives the first signal and turns
on one of the switching elements according to the control signal so
as to convert the first signal and output an output signal. In
addition, the conversion-sensing circuit includes a Schmitt trigger
or any other waveform shaping circuit. The time interval is equal
to one third of a time difference between a rising edge and a
falling edge of a voltage waveform of the second signal; otherwise,
the time interval is equal to a time difference between a rising
edge of one of the voltage waveforms of the second signal and a
falling edge of the other of the voltage waveforms of the second
signal.
[0012] In addition, the control signal generating circuit obtains a
frequency of the first signal according to the time interval.
Besides, the control signal generating circuit controls the
switching circuit according to information of a corresponding
voltage peak value of the first signal during a certain interval.
Otherwise, the control signal generating circuit controls the
switching circuit by way of space vector pulse width
modulation.
[0013] The power conversion apparatus further includes a first
energy storage unit and a second energy storage unit. The first
energy storage unit is electrically connected with the power
generation apparatus and the switching circuit. The first energy
storage unit stores and releases electric power generated by the
power generation apparatus according to turn-on and turn-off of the
switching elements, respectively. The second energy storage unit is
electrically connected with the switching circuit and stores
electric power of the output signal.
[0014] The power conversion apparatus further includes a brake
energy recovery circuit electrically connected with the switching
circuit. The brake energy recovery circuit has a switch unit, a
first energy storage element and a second energy storage element.
The switch unit is electrically connected with a first terminal of
the first energy storage element, and a second terminal of the
first energy storage element is electrically connected with a first
terminal of the second energy storage element. In addition, the
switch unit has a first switch element electrically connected with
the first terminal of the first energy storage element. The first
energy storage element stores braking energy of the power
generation apparatus when the first switch element turns on, and
the second energy storage element stores energy released from the
first energy storage element when the first switch element turns
off. The switch unit further has a second switch element
electrically connected with a first terminal of the first switch
element and the first terminal of the first energy storage element.
The first energy storage element stores energy released from the
second energy storage element when the second switch element turns
on, and the first energy storage element releases the stored energy
to the power generation apparatus when the second switch element
turns off.
[0015] To achieve the above objective, the present invention
further discloses a controlling method applied with a power
conversion apparatus. The power conversion apparatus comprises a
conversion-sensing circuit, a control signal generating circuit and
a switching circuit. A power generation apparatus outputs a first
signal inputted to the power conversion apparatus. The controlling
method comprising: sensing the first signal and converting the
first signal into a second signal via the conversion-sensing
circuit; sensing at least one voltage waveform change of the second
signal and generating a time interval via the conversion-sensing
circuit; outputting a control signal via the control signal
generating circuit and according to the time interval; and turning
on one of a plurality of switching elements of the switching
circuit via the switching circuit and according to the control
signal, and converting the first signal into an output signal and
outputting the output signal. Herein, the time interval is equal to
one third of a time difference between a rising edge and a falling
edge of a voltage waveform of the second signal; otherwise, the
time interval is equal to a time difference between a rising edge
of one of the voltage waveforms of the second signal and a falling
edge of the other of the voltage waveforms of the second
signal.
[0016] In addition, the control signal generating circuit obtains a
frequency of the first signal according to the time interval.
Besides, the control signal generating circuit controls the
switching circuit according to information of a corresponding
voltage peak value of the first signal during a certain
interval.
[0017] The power conversion apparatus further includes a brake
energy recovery circuit electrically connected with the switching
circuit. The brake energy recovery circuit has a switch unit, a
first energy storage element and a second energy storage
element.
[0018] The first energy storage element stores braking energy of
the power generation apparatus when a first switch element of the
switch unit turns on, and the second energy storage element stores
energy released from the first energy storage element when the
first switch element turns off.
[0019] In addition, the first energy storage element stores energy
released from the second energy storage element when a second
switch element of the switch unit turns on, and the first energy
storage element releases the stored energy to the power generation
apparatus when the second switch element turns off.
[0020] To achieve the above objective, the present invention
further discloses a power conversion apparatus including a control
signal generating circuit and a brake energy recovery circuit. The
control signal generating circuit is electrically connected with
the power generation apparatus and outputs a control signal
according to a first signal generated by the power generation
apparatus. The brake energy recovery circuit is electrically
connected with the power generation apparatus and the control
signal generating circuit. The control signal controls the brake
energy recovery circuit to store energy generated when the power
generation apparatus brakes, and controls the brake energy recovery
circuit to release the stored electric power to the power
generation apparatus.
[0021] As mentioned above, the power conversion apparatus of the
invention utilizes the conversion-sensing circuit to convert the
first signal into the second signal and to sense at least one
voltage waveform change of the second signal to generate the time
interval, so as to obtain the instantaneous rotating speed and the
frequency of the power generation apparatus and achieve the control
of the instantaneous rotating speed. Thus, the prior art position
detector can be replaced, and it is unnecessary to provide the
power for the position detector so that no long distance line loss
occurs. In addition, the control signal generating circuit of the
invention outputs the control signal according to the time interval
so as to control one of the switching elements of the switching
circuit to turn on and off, and the first signal is converted and
outputted. Because only the switch operation of one switching
element is switched in one duration, the power consumption of the
switching element can be decreased, the current harmonic wave of
the output signal can be minimized, and the power conversion
apparatus has the full power and high efficiency energy
conversion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The present invention will become more fully understood from
the subsequent detailed description and accompanying drawings,
which are given by way of illustration only, and thus are not
limitative of the present invention, and wherein:
[0023] FIG. 1 is a schematic illustration showing a power
conversion apparatus according to a preferred embodiment of the
invention;
[0024] FIGS. 2A and 2B are schematic illustrations showing
waveforms of three-phase line voltages of a first signal and a
second signal of the power conversion apparatus, respectively;
[0025] FIGS. 3A to 3C, 4A to 4C, 5A to 5C, 6A to 6C, 7A to 7C, and
8A to 8C are schematic illustrations showing waveforms of the first
signal of the power conversion apparatus of the invention and
operations of different switching elements, respectively;
[0026] FIG. 9 is a schematic illustration showing a power
conversion apparatus according to another preferred embodiment of
the invention;
[0027] FIGS. 10A to 10D are schematic illustrations showing
operations of the brake energy recovery circuit of FIG. 9,
respectively; and
[0028] FIGS. 11 and 12 are schematic flow charts showing different
controlling methods of the power conversion apparatus of the
invention, respectively.
DETAILED DESCRIPTION OF THE INVENTION
[0029] The present invention will be apparent from the following
detailed description, which proceeds with reference to the
accompanying drawings, wherein the same references relate to the
same elements.
[0030] FIG. 1 is a schematic illustration showing a power
conversion apparatus 1 according to a preferred embodiment of the
invention. Referring to FIG. 1, a power conversion apparatus 1 may
be applied with a power generation apparatus G. The power
generation apparatus G may output a first signal S1, which is a
three-phases balanced sine wave voltage signal with the stable
phase sequence. The power generation apparatus G may be, for
example but without limitation to, a wind power generator of a wind
power generation system, and may also be another power generation
apparatus, such as a thermal power generation apparatus, a
waterpower power generation apparatus, a solar power generation
apparatus or any other power generation apparatus. In addition, the
output, after the conversion of the power conversion apparatus 1,
can charge the battery module for storage, and may also be supplied
to the load or may be connected to the power supply grid in
parallel. However, the invention is not particularly restricted
thereto.
[0031] The power conversion apparatus 1 includes a
conversion-sensing circuit 11, a control signal generating circuit
12 and a switching circuit 13. In addition, the power conversion
apparatus 1 may further include a first energy storage unit 14 and
a second energy storage unit 15.
[0032] The conversion-sensing circuit 11 can sense the first signal
S1, and convert the first signal S1 into a second signal S2. Please
refer to FIGS. 1, 2A and 2B, wherein FIGS. 2A and 2B are schematic
illustrations showing waveforms of three-phase line voltages of the
first signal S1 and the second signal S2 of the power conversion
apparatus, respectively.
[0033] The first signal S1 is a three-phase balanced sine wave
voltage signal with the stable phase sequence. So, it is possible
to sense the first signal S1 via, for example, a potential
transformer (PT, not shown), and to utilize the conversion-sensing
circuit 11 to convert the first signal S1 into the second signal
S2. The conversion-sensing circuit 11 may include a Schmitt trigger
or any other waveform shaping circuit. In this embodiment, the
Schmitt trigger functions as the waveform shaping circuit, and can,
for example, convert the voltage transition points of the
three-phase sine wave first signal S1 (line voltages V.sub.ab,
V.sub.bc and V.sub.ca) of FIG. 2A into the square wave signals
(i.e., the second signal S2) with the rising and falling edges,
respectively. As shown in FIG. 2B, taking the line voltage V.sub.ab
as an example, the sine wave changes from the negative polarity to
the positive polarity at 0.degree., so that a rising edge of the
second signal S2 can be obtained. In addition, the sine wave
changes from the positive polarity to the negative polarity at
180.degree., so that a falling edge of the second signal S2 is
obtained, and so on. Therefore, as shown in FIG. 2B, the line
voltages V.sub.ab, V.sub.bc and V.sub.ca of the first signal S1 may
be respectively converted into the square waves of the second
signal S2, and the three square waves of the second signal S2
correspond to the line voltages V.sub.ab, V.sub.bc and V.sub.ca of
the first signal S1.
[0034] In addition, the conversion-sensing circuit 11 can sense at
least one voltage waveform change of the second signal S2 to
generate a time interval. Herein, the time interval is, for
example, equal to one third of a time difference between a rising
edge and a falling edge of a certain line voltage waveform of the
second signal S2. Specifically, taking the line voltage V.sub.ab of
the first signal S1 of FIG. 2B as an example, the time difference
between the rising edge and the falling edge of the line voltage
waveform of the second signal S2 is the time required for the
waveform of the line voltage V.sub.ab to change from 0.degree. to
180.degree. (i.e., a half period of the line voltage V.sub.ab), so
one time interval is equal to the time required for the phase of
the first signal S1 to change 60.degree. (180/3).
[0035] In addition, in another implemented example, the time
interval may also be equal to the time difference between the
rising edge of one voltage waveform of the second signal S2 and the
falling edge of the other voltage waveform of the second signal S2.
Herein, as shown in FIG. 2A, the time difference between the rising
edge of one line voltage waveform of the second signal S2 and the
falling edge of the other line voltage waveform of the second
signal S2 is also the time required for the waveform of the first
signal S1 to change 60.degree..
[0036] After the time interval is obtained, the control signal
generating circuit 12 can calculate to obtain the period of the
first signal S1 (the period is equal to 6 times of the time
interval) and the frequency (the frequency is equal to 1/period)
according to the time interval so as to obtain the instantaneous
rotating speed and the frequency of the power generation apparatus
G. Thus, the power conversion apparatus 1 can achieve the control
of the instantaneous rotating speed. Not only the prior art
position detector (the price of the position detector is high) is
needed, but the power of the position detector needs not to be
provided and the long distance line loss is eliminated. More
specifically, the invention does not intend to restrict the time
interval to the time for the first signal S1 to change 60.degree..
In other aspects, the time interval may also be the time required
for the change of 30.degree. or any other angle. Alternatively,
utilizing the first signal S1 to perform the mathematical
calculation can also obtain the instantaneous rotating speed and
the frequency of the power generation apparatus G.
[0037] With reference to FIG. 1, the control signal generating
circuit 12 is electrically connected with the conversion-sensing
circuit 11 and can output a control signal CS according to the time
interval. The control signal CS is a pulse width modulation (PWM)
signal and can include the information of the instantaneous
rotating speed and the frequency of the power generation apparatus
G. The control signal generating circuit 12 can output the control
signal CS to control the switching circuit 13 according to the
information of a corresponding voltage peak value of the first
signal S1 during a certain interval. The control signal generating
circuit 12 can control the switching circuit 13 via the space
vector pulse width modulation (SVPWM) or the sinusoidal pulse width
modulation (SPWM).
[0038] The switching circuit 13 is electrically connected with the
power generation apparatus G and the control signal generating
circuit 12. In addition, the switching circuit 13 may also be
electrically connected with the first energy storage unit 14 and
the second energy storage unit 15. The switching circuit 13 has a
plurality of switching elements 131a to 131f and a plurality of
diodes 132a to 132f The diodes 132a to 132f are disposed
respectively corresponding to the switching elements 131a to 131f
Herein, the switching elements 131a to 131f may be power
transistors, respectively, and the six diodes 132a to 132f are
connected in parallel to the six switching elements 131a to 131f in
one-to-one manners, respectively. In addition, the switching
circuit 13 can receive the first signal S1 and can turn on one of
the switching elements 131a to 131f according to the control signal
CS so as to convert the first signal S1 and output an output signal
OS.
[0039] As shown in FIG. 1, the first energy storage unit 14 is
electrically connected with the power generation apparatus G and
the switching circuit 13, and can turn on and off according to the
switching elements 131a to 131f to store and release the electric
power of the first signal S1, respectively. Herein, the first
energy storage unit 14 has, from top to bottom, three inductors
141a, 141b and 141c, which are electrically connected with the
three-phase circuit at the output of the power generation apparatus
G and the switching circuit 13. The inductor 141a is electrically
connected with the switching elements 131a and 131b and the diodes
132a and 132b, the inductor 141b is electrically connected with the
switching elements 131c and 131d and the diodes 132c and 132d, and
the inductor 141c is electrically connected with the switching
elements 131e and 131f and the diodes 132e and 132f. In addition,
the second energy storage unit 15 is electrically connected with
the switching circuit 13 and can store the electric power outputted
from the power conversion apparatus 1. Herein, the second energy
storage unit 15 is a capacitor capable of storing the electric
power of the output signal OS. Of course, in other aspects, the
output signal OS outputted from the switching circuit 13 may also
be supplied to other load apparatuses, or may be used in other
applications. In addition, the power conversion apparatus 1 may
further include a filter unit 17, which is disposed between the
first energy storage unit 14 and the power generation apparatus G
and electrically connected with the first energy storage unit 14
and the power generation apparatus G. The filter unit 17 may
include three capacitors electrically connected between the first
energy storage unit 14 and the power generation apparatus G in a
Y-shape connection manner. The filter unit 17 can filter out the
noise to stabilize the voltage signals inputted to and outputted
from the power generation apparatus G.
[0040] Hereinbelow, illustrations will be made with reference to
the associated drawings to describe how the control signal CS
controls one of the switching elements 131a to 131f so as to
convert the first signal S1 and generate the output signal OS to
make the power conversion apparatus 1 have the high conversion
efficiency.
[0041] Please refer to FIGS. 3A to 8C, which are schematic
illustrations showing waveforms of the first signal S1 of the power
conversion apparatus 1 of the invention and operations of different
switching elements, respectively. It is to be firstly specified
that some elements are not shown in FIGS. 3A to 8C. For example,
the power generation apparatus G, the conversion-sensing circuit
11, the control signal generating circuit 12 and the inductor 141a
of the first energy storage unit 14 are not shown in FIGS. 3B and
3C. In addition, the switching elements 131a and 131b and 131d to
131f, which do not operate, are not shown, either. In addition, no
filter unit 17 is shown in FIGS. 3A to 8C.
[0042] As shown in FIGS. 3A and 3B of this embodiment, when the
first signal S1 is in the duration from 0.degree. to 60.degree.,
the line voltage V.sub.bc has the voltage peak value (as shown in
the zone A) higher than the line voltage V.sub.ab and the line
voltage V.sub.ca. The control signal generating circuit 12 can
output the control signal CS when the line voltage V.sub.bc has the
peak value and when the first signal S1 is in the duration from
0.degree. to 60.degree., so as to control the switching element
131c to switch and make the power conversion apparatus 1 have the
high conversion efficiency.
[0043] As shown in FIG. 3B, the control signal CS (not shown) only
turns on the switching element 131c and generates the loop of the
current i via the inductor 141c, the diode 132e, the switching
element 131c and the inductor 141b according to the line voltage
V.sub.bc, so that the inductors 141b and 141c can store the
electric power of the line voltage V.sub.bc. In addition, as shown
in FIG. 3C, the control signal CS (not shown) is again utilized to
control the switching element 131c to turn off, the electric power
stored in the inductors 141b and 141c can be converted and
outputted to the second energy storage unit 15 for storage through
the loop of the current i via the inductor 141c, the diode 132e,
the diode 132d and the inductor 141b.
[0044] In addition, as shown in FIGS. 4A and 4B of this embodiment,
when the first signal S1 is in the duration from 60.degree. to
120.degree., the line voltage V.sub.ab has the voltage peak value
(as shown in the zone B) higher than the line voltage V.sub.bc and
the line voltage V.sub.ca. The control signal generating circuit 12
can output the control signal CS when the line voltage V.sub.ab has
the peak value and when the first signal S1 is in the duration from
60.degree. to 120.degree., so as to control the switching element
131b to switch and make the power conversion apparatus 1 have the
high conversion efficiency.
[0045] As shown in FIG. 4B, the control signal CS (not shown) only
turns on the switching element 131b and generates the loop of the
current i via the inductor 141a, the switching element 131b, the
diode 132d and the inductor 141b according to the line voltage
V.sub.ab, so that the inductors 141a and 141b can store the
electric power of the line voltage V.sub.ab. In addition, as shown
in FIG. 4C, the control signal CS (not shown) is again utilized to
control the switching element 131b to turn off and the electric
power stored in the inductors 141a and 141b can be converted and
outputted to the second energy storage unit 15 for storage through
the loop of the current i via the inductor 141a, the diode 132a,
the diode 132d and the inductor 141b.
[0046] In addition, as shown in FIGS. 5A and 5B of this embodiment,
when the first signal S1 is in the duration from 120.degree. to
180.degree., the line voltage V.sub.ca has the voltage peak value
(as shown in the zone C) higher than the line voltage V.sub.bc and
the line voltage V.sub.ab. The control signal generating circuit 12
can output the control signal CS when the line voltage V.sub.ca has
the peak value and when the first signal S1 is in the duration from
120.degree. to 180.degree., so as to control the switching element
131e to switch and make the power conversion apparatus 1 have the
high conversion efficiency.
[0047] As shown in FIG. 5B, the control signal CS (not shown) only
turns on the switching element 131e and generates the loop of the
current i via the inductor 141a, the diode 132a, the switching
element 131e and the inductor 141c according to the line voltage
V.sub.ca, so that the inductors 141a and 141c can store the
electric power of the line voltage V.sub.ca. In addition, as shown
in FIG. 5C, the control signal CS (not shown) is again utilized to
control the switching element 131e to turn off, and the electric
power stored in the inductors 141a and 141c can be converted and
outputted to the second energy storage unit 15 for storage through
the loop of the current i via the inductor 141a, the diode 132a,
the diode 132f and the inductor 141c.
[0048] In addition, as shown in FIGS. 6A and 6B of this embodiment,
when the first signal S1 is in the duration from 180.degree. to
240.degree., the line voltage V.sub.bc has the voltage peak value
(as shown in the zone D) higher than the line voltage V.sub.ab and
the line voltage V.sub.ca. The control signal generating circuit 12
can output the control signal CS when the line voltage V.sub.bc has
the peak value and when the first signal S1 is in the duration from
180.degree. to 240.degree., so as to control the switching element
131d to switch and make the power conversion apparatus 1 have the
high conversion efficiency.
[0049] As shown in FIG. 6B, the control signal CS (not shown) only
turns on the switching element 131d and generates the loop of the
current i via the inductor 141b, the switching element 131d, the
diode 132f and the inductor 141c according to the line voltage
V.sub.bc, so that the inductors 141b and 141c can store the
electric power of the line voltage V.sub.bc. In addition, as shown
in FIG. 6C, the control signal CS (not shown) is again utilized to
control the switching element 131d to turn off and the electric
power stored in the inductors 141b and 141c can be converted and
outputted to the second energy storage unit 15 for storage through
the loop of the current i via the inductor 141b, the diode 132c,
the diode 132f and the inductor 141c.
[0050] In addition, as shown in FIGS. 7A and 7B of this embodiment,
when the first signal S1 is in the duration from 240.degree. to
300.degree., the line voltage V.sub.ab has the voltage peak value
(as shown in the zone E) higher than the line voltage V.sub.bc and
the line voltage V.sub.ca. The control signal generating circuit 12
can output the control signal CS when the line voltage V.sub.ab has
the peak value and when the first signal S1 is in the duration from
240.degree. to 300.degree., so as to control the switching element
131a to switch and make the power conversion apparatus 1 have the
high conversion efficiency.
[0051] As shown in FIG. 7B, the control signal CS (not shown) only
turns on the switching element 131a and generates the loop of the
current i via the inductor 141b, the diode 132c, the switching
element 131a and the inductor 141a according to the line voltage
V.sub.ab, so that the inductors 141a and 141b can store the
electric power of the line voltage V.sub.ab. In addition, as shown
in FIG. 7C, the control signal CS (not shown) is again utilized to
control the switching element 131a to turn off, and the electric
power stored in the inductors 141a and 141b can be converted and
outputted to the second energy storage unit 15 for storage through
the loop of the current i via the inductor 141b, the diode 132c,
the diode 132b and the inductor 141a.
[0052] In addition, as shown in FIGS. 8A and 8B of this embodiment,
when the first signal S1 is in the duration from 300.degree. to
360.degree. (or 0.degree.), the line voltage V.sub.ca has the
voltage peak value (as shown in the zone F) higher than the line
voltage V.sub.bc and the line voltage V.sub.ab. The control signal
generating circuit 12 can output the control signal CS when the
line voltage V.sub.ca has the peak value and when the first signal
S1 is in the duration from 300.degree. to 360.degree., so as to
control the switching element 131f to switch and make the power
conversion apparatus 1 have the high conversion efficiency.
[0053] As shown in FIG. 8B, the control signal CS (not shown) only
turns on the switching element 131f and generates the loop of the
current i via the inductor 141c, the switching element 131f, the
diode 132b and the inductor 141a according to the line voltage
V.sub.ca, so that the inductors 141a and 141c can store the
electric power of the line voltage V.sub.ca. In addition, as shown
in FIG. 8C, the control signal CS (not shown) is again utilized to
control the switching element 131f to turn off, and the electric
power stored in the inductors 141a and 141c can be converted and
outputted to the second energy storage unit 15 for storage through
the loop of the current i via the inductor 141c, the diode 132e,
the diode 132b and the inductor 141a.
[0054] As mentioned hereinabove, the power generation apparatus G
of the invention can convert the first signal S1 into the second
signal S2 via the conversion-sensing circuit 11 upon the low power
output, and sense at least one voltage waveform change of the
second signal S2 to generate the time interval, so as to obtain the
instantaneous rotating speed and the frequency of the power
generation apparatus G and make the power conversion apparatus 1
achieve the control of the instantaneous rotating speed. Not only
the prior art position detector (the price of the position detector
is high) is needed, but the power of the position detector needs
not to be provided and the long distance line loss is eliminated.
In addition, the control signal generating circuit 12 is further
utilized to output the control signal CS according to the time
interval, so as to control one of the switching elements of the
switching circuit 13 to turn on and off via the SVPWM or the SPWM.
Because only the on/off operation of one switching element is
switched in one duration, the switch power consumption of the power
transistor can be reduced, and the current harmonic wave of the
output signal OS can be minimized, so that the power conversion
apparatus 1 has the high efficiency energy conversion upon the low
power output of the power generation apparatus G. In addition, upon
the high power output of the power generation apparatus G, the
power conversion apparatus 1 can simultaneously switch the
operations of six switching elements 131a to 131f via the SVPWM or
the SPWM, so that the output electric power of the power generation
apparatus G can be converted. Similarly, the control signal CS of
the SVPWM or the SPWM can also be generated by the
conversion-sensing circuit 11 via the control signal generating
circuit 12. Therefore, the power conversion apparatus 1 of the
invention has the advantages of the full power and high efficiency
energy conversion as well as the lower power loss.
[0055] In addition, please refer to FIG. 9, which is a schematic
illustration showing a power conversion apparatus 1a according to
another preferred embodiment of the invention.
[0056] What is mainly different from the power conversion apparatus
1 of the FIG. 1 is that the power conversion apparatus 1a may
further include a brake energy recovery circuit 16 electrically
connected with the switching circuit 13 and the second energy
storage unit 15. The brake energy recovery circuit 16 can recover
the electric power generated when the power generation apparatus G
is braking. When no wind or the breeze is present, the stored
electric power controls the switching circuit 13 to operate through
the control signal generating circuit 12 by way of the SVPWM or the
SPWM, and the first energy storage unit 14 and the filter unit 17
filter out the noise signal and then release the energy to the
power generation apparatus G to start the blades and to solve the
problem of the starting inertia of the power generation apparatus
G. Thus, it is possible to solve the problems, such as the
overheating of the brake resistor, the too long starting time of
the control device or the output module, the missed short energy
receiving, the brake resistor loss caused by the incomplete
starting of the output module, the long-term waste of the
considerable energy and the like, encountered during the prior art
electric power conversion processes.
[0057] The brake energy recovery circuit 16 has a switch unit, a
first energy storage element 162 and a second energy storage
element 163. In this embodiment, the switch unit may have a first
switch element 161a and a second switch element 161b. In addition,
the switch unit may further have two diodes 164a and 164b
respectively connected in parallel to the first switch element 161a
and the second switch element 161b. Herein, the diode 164a is
connected in parallel to the first switch element 161a, and the
diode 164b is connected in parallel to the second switch element
161b. In addition, the first switch element 161a, the diode 164a,
the second switch element 161b and the diode 164b are electrically
connected with the first terminal of the first energy storage
element 162, the second terminal of the first energy storage
element 162 is electrically connected with the first terminal of
the second energy storage element 163, and the second terminal of
the second energy storage element 163 is electrically connected
with the second switch element 161b and the diode 164b. In this
embodiment, the first energy storage element 162 is an inductor,
and the second energy storage element 163 is a capacitor, and may
be a super capacitor or any other elements capable of storing
energy.
[0058] Please refer to FIGS. 10A to 10D, which are schematic
illustrations showing operations of the brake energy recovery
circuit 16 of FIG. 9, respectively, wherein the conversion-sensing
circuit 11 and the control signal generating circuit 12 are not
shown in FIGS. 10A to 10D. In addition, the switch elements of the
switch unit, which do not operate, are also not shown. For example,
the second switch element 161b is not shown in FIGS. 10A and
10B.
[0059] In this embodiment, as shown in FIG. 10A, when the power
generation apparatus G is braking, the brake energy recovery
circuit 16 can recover the electric power generated when the power
generation apparatus G is braking. Herein, the control signal
generating circuit 12 (not shown in FIG. 10A) can be utilized to
control the first switch element 161a of the brake energy recovery
circuit 16 to turn on by way of PWM, and the current I generated by
the brake energy can be stored by the first energy storage element
162 (the inductor stores the energy) via the first switch element
161a. In addition, as shown in FIG. 10B, the control signal
generating circuit 12 (not shown in FIG. 10B) is again utilized to
control the first switch element 161a of the brake energy recovery
circuit 16 to turn off by way of PWM, so that the energy stored in
the first energy storage element 162 can be released and stored to
the second energy storage element 163 (the inductor releases the
energy).
[0060] In addition, as shown in FIG. 10C, when the power generation
apparatus G is to be started at no wind or at the breeze, the
second switch element 161b can be controlled to turn on, and the
second energy storage element 163 can release the stored electric
power, which is received by the first energy storage element 162
(the inductor stores the energy). In addition, as shown in FIG.
10D, by controlling the second switch element 161b to turn off, the
energy stored in the first energy storage element 162 can be
released (the inductor releases the energy) to the second energy
storage unit 15, and the power generation apparatus G can convert
the reverse first signal S1, generated by the second energy storage
unit 15, via the switching circuit 13, so that the power generation
apparatus G becomes a motor to start the blades and solve the
problem of the starting inertia of the power generation apparatus
G. When no wind is present, this energy may also be released to any
load electrically connected with the second energy storage unit 15.
The signals for controlling the first switch element 161a and the
second switch element 161b may be PWM signals, and may be generated
by the control signal generating circuit 12 or another control
circuit. Herein, the invention is not particularly restricted
thereto.
[0061] In addition, the technological characteristics of the power
conversion apparatus 1a can be obtained with reference to the power
conversion apparatus 1, so detailed descriptions thereof will be
omitted.
[0062] In addition, please refer to FIGS. 1 and 11 simultaneously,
wherein FIG. 11 is a schematic flow chart showing a controlling
method of the power conversion apparatus of the invention.
[0063] The controlling method of the invention is applied with the
power conversion apparatus 1. The power conversion apparatus 1
includes a conversion-sensing circuit 11, a control signal
generating circuit 12 and a switching circuit 13, wherein a power
generation apparatus G outputs a first signal S1 inputted to the
power conversion apparatus 1. The controlling method includes the
following steps. In step S01, the conversion-sensing circuit 11
senses and converts the first signal S1 into a second signal S2. In
step S02, the conversion-sensing circuit 11 senses at least one
voltage waveform change of the second signal S2 and generates a
time interval. In step S03, the control signal generating circuit
12 outputs a control signal CS according to the time interval. In
step S04, the switching circuit 13 turns on one of a plurality of
switching elements 131a to 131f of the switching circuit 13
according to the control signal CS, so as to convert the first
signal S1 and output an output signal OS.
[0064] In addition, please refer to FIGS. 9 and 12 simultaneously,
wherein FIG. 12 is a schematic flow chart showing another
controlling method of the power conversion apparatus of the
invention.
[0065] The controlling method of the invention may further include
the following steps S05 and S06. In the step S05, a first switch
element 161a of the switch unit is controlled to turn on, so as to
store the braking energy of the power generation apparatus G to the
first energy storage element 162. In the step S06, the first switch
element 161a is controlled to turn off to store the energy,
released from the first energy storage element 162, to the second
energy storage element 163. In addition, the controlling method may
further include the following steps S07 and S08. In the step S07, a
second switch element 161b of the switch unit is controlled to turn
on to store the energy, released from the second energy storage
element 163, to the first energy storage element 162. In the step
S08, the second switch element 161b is controlled to turn off to
release the energy, released from the first energy storage element
162, to the power generation apparatus G.
[0066] In addition, the technological characteristics of the power
conversion apparatus and the controlling method thereof have been
described hereinabove, so detailed descriptions thereof will be
omitted.
[0067] In summary, the power conversion apparatus of the invention
utilizes the conversion-sensing circuit to convert the first signal
into the second signal and to sense at least one voltage waveform
change of the second signal to generate the time interval, so as to
obtain the instantaneous rotating speed and the frequency of the
power generation apparatus and achieve the control of the
instantaneous rotating speed. Thus, the prior art position detector
can be replaced, and it is unnecessary to provide the power for the
position detector so that no long distance line loss occurs. In
addition, the control signal generating circuit of the invention
outputs the control signal according to the time interval so as to
control one of the switching elements of the switching circuit to
turn on and off, and the first signal is converted and outputted.
Because only the switch operation of one switching element is
switched in one duration, the power consumption of the switching
element can be decreased, the current harmonic wave of the output
signal can be minimized, and the power conversion apparatus has the
full power and high efficiency energy conversion.
[0068] Although the present invention has been described with
reference to specific embodiments, this description is not meant to
be construed in a limiting sense. Various modifications of the
disclosed embodiments, as well as alternative embodiments, will be
apparent to persons skilled in the art. It is, therefore,
contemplated that the appended claims will cover all modifications
that fall within the true scope of the present invention.
* * * * *