CN102593937A - Power conversion circuit - Google Patents

Abstract

The invention relates to a power conversion circuit, which utilizes a control module to control a pulse wave regulating circuit according to the output voltage and the output current of a renewable energy power supply device and the direct current link voltage of a direct current/direct current converter so as to regulate and control the duty cycle of the direct current/direct current converter. And the control module is used for controlling the pulse wave regulating circuit according to the output voltage and the output current of the renewable energy power supply device, the direct current link voltage of the direct current/direct current converter and the output voltage of the commercial power supply device so as to regulate and control the duty cycle of the direct current/alternating current converter.

Description

power conversion circuit

technical field

The invention relates to a parallel connection technology of commercial power, in particular to a power conversion circuit applied to a parallel renewable energy system of commercial power.

Background technique

Renewable energy refers to theoretically inexhaustible natural resources, such as solar energy, wind energy, geothermal energy, hydropower energy, tidal energy, biomass energy, etc., which are converted into energy from nature. In order to enable human beings to develop sustainably on the earth, the effective and economical conversion of renewable energy into general livelihood power supply has become an important industrial development policy for advanced technological countries that take into account both power generation and environmental protection.

In the green renewable energy system, the mains parallel technology plays an important role. With the mains parallel connection technology, when the power generated by the renewable energy power supply device is insufficient to supply the load or the supply of the renewable energy power supply device fails, the mains power supply device can supply power to the load. Among them, when the power generated by the renewable energy power supply device is not enough to supply the load and the insufficient power is supplied by the mains power supply device, the phase and frequency of the output voltage of the converter between the two must be consistent with the mains. . In addition, when the power generated by the renewable energy power supply device is still too much after being supplied to the load, it can be fed back to the power company.

FIG. 1 is a schematic structural diagram of a conventional utility power parallel-connected renewable energy system.

Please refer to FIG. 1 , the conventional parallel-connected mains renewable energy system includes: a renewable energy power supply device 10 , a power conversion circuit 20 , a mains power supply device 30 and a load 40 .

The power conversion circuit 20 includes a controller 24 , a DC/DC converter 210 , a DC/AC converter 220 and an output circuit 230 .

The DC/DC converter 210 receives the renewable energy generated by the renewable energy power supply device 10 and converts it into stable and fixed DC power. The DC/AC converter 220 converts the DC power output by the DC/DC converter 210 into AC power. The controller 24 is used to control the operation of the renewable energy power supply device 10 , the DC/DC converter 210 , the DC/AC converter 220 and the output circuit 230 . The output circuit 230 can provide AC power and/or commercial power to the load 40 according to the control of the controller 24 .

In the mains parallel technology, the detection of the angular position of the AC power output by the DC/AC converter 220 and the angular position of the mains is a key index of efficiency. Traditional angular position detection technology can be divided into zero point detection circuit and digital phase-locked loop. However, the cost of the zero point detection circuit is relatively high and it is easily disturbed to cause misjudgment of the angular position. Although the response speed of the digital phase-locked loop is fast and the accuracy is good, the design of the controller is not easy.

It can be seen that the above-mentioned existing mains parallel connection technology obviously still has inconvenience and defects in method and use, and needs to be further improved urgently. In order to solve the above-mentioned problems, the relevant manufacturers have tried their best to find a solution, but no suitable design has been developed for a long time, and the general method has no suitable method to solve the above-mentioned problems. This is obviously related. The problem that the industry is eager to solve. Therefore, how to create a new power conversion circuit is one of the current important research and development topics, and it has also become a goal that the industry needs to improve.

Contents of the invention

The main purpose of the present invention is to overcome the defects existing in the existing mains parallel technology and provide a new power conversion circuit. The technical problem to be solved is to use the current closed-loop control method to control the operation of the DC/DC converter , and the operation control of the DC/AC converter is carried out by adopting the closed-loop control method of the outer circulation voltage and the closed-loop control method of the inner circulation current, so as to greatly reduce the size of the hardware circuit, which is very suitable for practical use.

The purpose of the present invention and the solution to its technical problems are achieved by adopting the following technical solutions. According to the power conversion circuit of the present invention, it includes: a first receiving end, used to electrically connect a renewable energy power supply device; a second receiving end, used to receive a commercial power; a load end, used to electrically connect A load; a DC/DC converter, the input end of the DC/DC converter is electrically connected to the first receiving end, so as to correspond to the duty cycle of a first modulation signal to output the voltage of the renewable energy power supply device into a stable DC link voltage; a DC/AC converter, the input terminal of the DC/AC converter is electrically connected to the output terminal of the DC/DC converter to receive the DC link voltage and generate a corresponding converting the DC link voltage into an AC link voltage during a duty cycle of a second modulation signal; an output circuit electrically connected to the output terminal of the DC/AC converter, the second receiving terminal and the load terminal, The load power is supplied by one of the AC link voltage and the commercial power; a feedback circuit is electrically connected to the first receiving end, the output end of the DC/DC converter, and the DC/AC converter The output terminal and the second receiving terminal are used to feed back a first feedback signal corresponding to the output voltage of the renewable energy power supply device and a second feedback signal corresponding to the output current of the renewable energy power supply device , a third feedback signal corresponding to the DC link voltage of the DC/DC converter, a fourth feedback signal corresponding to the output current of the DC/AC converter, and a fourth feedback signal corresponding to the output voltage of the commercial power A fifth feedback signal; a detection circuit, electrically connected to the feedback circuit, to receive the fifth feedback signal and perform calculations based on the fifth feedback signal to obtain a corner position of the mains; a control module, electrically connected to the feedback circuit and the detection circuit, to convert the fourth feedback signal and the fifth feedback signal from two-axis stator coordinates to rotor coordinates according to the angular position, Outputting a first control signal according to the first feedback signal, the second feedback signal and the third feedback signal, and outputting a first control signal according to the first feedback signal, the second feedback signal and the third feedback signal And the fourth feedback signal and the fifth feedback signal represented by the rotor coordinates output a second control signal; and a pulse wave adjustment circuit, electrically connected to the control module, for according to the first control signal Outputting the first modulation signal, and outputting the second modulation signal according to the second control signal.

The purpose of the present invention and its technical problems can also be further realized by adopting the following technical measures.

The aforementioned power conversion circuit, wherein the detection circuit includes: a second-order digital quadrature converter, electrically connected to the feedback circuit, to receive the fifth feedback signal and generate a signal corresponding to the city power a synchronous sine wave; and an arctangent calculation unit, electrically connected between the second-order digital quadrature converter and the control module, so as to calculate the sine wave of the mains power by using the sine wave synchronized with the mains power corner position.

In the aforementioned power conversion circuit, the control module includes: a coordinate conversion unit for converting the fourth feedback signal and the fifth feedback signal from a two-axis rotor coordinate representation to a coordinate conversion unit according to the angular position Stator coordinate representation; a first controller for outputting the first control signal according to the first feedback signal, the second feedback signal and the third feedback signal; and a second controller for outputting the first control signal according to the The first feedback signal, the second feedback signal, the third feedback signal, the fourth feedback signal and the fifth feedback signal represented by the stator coordinates and the angular position output the second control signal .

In the aforementioned power conversion circuit, the first controller includes: a subtractor, used to subtract a current command value from the second feedback signal; a current regulator, used to adjust the subtractor output value; an adder, used for adding the output value of the current regulator to the third feedback signal and subtracting the first feedback signal; The output value of the third feedback signal is converted into an inverse number to generate the first control signal.

The aforementioned power conversion circuit, wherein the fifth feedback signal represented by the stator coordinates includes a q-axis fifth feedback signal and a d-axis fifth feedback signal, and the second controller includes: a a power compensation unit for generating an input compensation value according to the first feedback signal, the second feedback signal and the fifth d-axis feedback signal; a d-axis control unit for generating an input compensation value according to the third feedback signal , the input compensation value, the fourth feedback signal expressed by the stator coordinates and the fifth feedback signal of the d-axis generate a d-axis control command; a q-axis control unit is used to generate a d-axis control command according to the stator coordinates The fourth feedback signal and the fifth feedback signal of the q-axis generate a q-axis control command; a coordinate inverse conversion unit is used to convert the d-axis control command and the q-axis control command from the stator coordinates according to the angular position expressing conversion to expressing in the two-axis rotor coordinates to generate a control command expressed in the two-axis rotor coordinates; The control command represented by the coordinates is operated to generate the second control signal.

The aforementioned power conversion circuit, wherein the fourth feedback signal represented by the stator coordinates includes a q-axis fourth feedback signal and a d-axis fourth feedback signal, and the d-axis control unit includes: a A subtracter, used to subtract the third feedback signal from a voltage command value; a voltage regulator, used to adjust the output value of the subtractor; a first totalizer, used to adjust the output value of the voltage regulator The output value is added to the input compensation value, and then the fourth feedback signal of the d-axis is subtracted; a current regulator is used to adjust the output value of the first totalizer; a multiplier is used to adjust the output value according to a specific multiplying the q-axis fourth feedback signal; and a second totalizer for adding the output value of the current regulator to the output value of the multiplier and subtracting the d-axis fifth feedback signal And the d-axis control command is generated.

The aforementioned power conversion circuit, wherein the fourth feedback signal represented by the stator coordinates includes a q-axis fourth feedback signal and a d-axis fourth feedback signal, and the q-axis control unit includes: a a subtractor, used to subtract a current command value from the fourth feedback signal of the q-axis; a current regulator, used to adjust the output value of the subtractor; a multiplier, used to multiply the d according to a specific multiplier axis fourth feedback signal; and a third totalizer for generating the q-axis control by adding the output value of the current regulator, the output value of the multiplier and the q-axis fifth feedback signal Order.

Compared with the prior art, the present invention has obvious advantages and beneficial effects. It can be seen from the above that, in order to achieve the above purpose, the present invention provides a power conversion circuit, which can be applied to a renewable energy system in a two-stage series connection mode.

The present invention is a power conversion circuit. In terms of DC/DC converters, current closed-loop control is adopted to control the DC/DC converter by feeding back the output voltage, output current and DC link voltage of the renewable energy power supply device. How much power is generated.

The present invention is a power conversion circuit. In terms of DC/AC converters, the DC link voltage is fed back to stabilize the DC link voltage; the d-q axis coordinates (rotor coordinates) are converted to reduce system control design. question.

The present invention is a power conversion circuit. In terms of DC/AC converters, the input power compensation control is used to adjust the DC link voltage so that the output DC link voltage will not have a huge change in the case of instantaneous load changes. amplitude changes to improve its stability.

The present invention is a power conversion circuit. In terms of the DC/AC converter, the angle position detection of the mains voltage is used to ensure that the output voltage of the DC/AC converter can be synchronized with the mains.

In order to achieve the above effects, the present invention provides a power conversion circuit, which includes: a first receiving end, used to electrically connect a renewable energy power supply device; a second receiving end, used to receive a commercial power; a load end, used to electrically connect a load; a DC/DC converter, the input end of the DC/DC converter is electrically connected to the first receiving end, so as to supply power to the renewable energy corresponding to the duty cycle of a first modulation signal The output voltage of the device is converted into a stable DC link voltage; a DC/AC converter, the input end of the DC/AC converter is electrically connected to the output end of the DC/DC converter to receive the DC link voltage and to Converting the DC link voltage into an AC link voltage corresponding to the duty cycle of a second modulating signal; an output circuit electrically connected to the output terminal of the DC/AC converter, the second receiving terminal and the load terminal, so that the AC One of the link voltage and the mains supply load power; a feedback circuit electrically connects the first receiving end, the output end of the DC/DC converter, the output end of the DC/AC converter and the second receiving end, so as to Feedback a first feedback signal corresponding to the output voltage of the renewable energy power supply device, a second feedback signal corresponding to the output current of the renewable energy power supply device, and a first feedback signal corresponding to the DC link voltage of the DC/DC converter Three feedback signals, a fourth feedback signal corresponding to the output current of the DC/AC converter and a fifth feedback signal corresponding to the output voltage of the mains; a detection circuit electrically connected to the feedback The circuit is used to receive the fifth feedback signal and perform calculation based on the fifth feedback signal to obtain a corner position of the mains; a control module is electrically connected to the feedback circuit and the detection circuit to convert the fourth feedback circuit according to the corner position The feedback signal and the fifth feedback signal are converted from the two-axis stator coordinates to the rotor coordinates, and a first control signal is output according to the first feedback signal, the second feedback signal and the third feedback signal, and according to the first feedback signal A feedback signal, a second feedback signal, a third feedback signal, and a fourth feedback signal represented by rotor coordinates and a fifth feedback signal output a second control signal; and a pulse wave adjustment circuit, electrically connected to the control module, for outputting the first modulation signal according to the first control signal, and outputting the second modulation signal according to the second control signal.

With the above technical solution, the power conversion circuit of the present invention has at least the following advantages and beneficial effects:

1. With this digital circuit design, the size of the hardware circuit can be greatly reduced.

2. The output voltage and output current of the renewable energy power supply device and the DC link voltage can be fed back to control the power generation of the DC/DC converter.

3. The DC link voltage can be stably controlled by feeding back the DC link voltage.

4. The d-q axis coordinate conversion can be used to convert the time-varying control factors into non-time-varying factors for control, making it easier to follow the system commands, thereby reducing the problem of system control design.

5. The input power compensation control can be used to adjust the DC link voltage, so as to improve its stability, and then effectively improve the system instantaneous.

6. It can accurately detect and calculate the angular position of the mains to ensure that the output voltage of the DC/AC converter can be synchronized with the mains.

To sum up, the present invention relates to a power conversion circuit, which uses a control module to control the pulse wave regulation circuit according to the output voltage and output current of the renewable energy power supply device and the DC link voltage of the DC/DC converter to regulate the DC/DC converter. duty cycle of the DC converter. Moreover, the control module is used to control the pulse wave regulation circuit according to the output voltage and output current of the renewable energy power supply device, the DC link voltage of the DC/DC converter, and the output voltage of the mains power supply device to regulate the duty cycle of the DC/AC converter . The present invention has significant progress in technology, has obvious positive effects, and is a novel, progressive and practical new design.

The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , the following preferred embodiments are specifically cited below, and are described in detail as follows in conjunction with the accompanying drawings.

Description of drawings

FIG. 1 is a schematic structural diagram of a conventional utility power parallel-connected renewable energy system.

FIG. 2 is a schematic structural diagram of the power conversion circuit of the first embodiment of the power conversion circuit of the present invention.

FIG. 3 is a schematic structural diagram of a detection circuit of an embodiment.

FIG. 4 is a schematic structural diagram of a control module of an embodiment.

FIG. 5 is a schematic structural diagram of a first controller according to an embodiment.

FIG. 6 is a schematic structural diagram of a second controller according to an embodiment.

FIG. 7 is a schematic structural diagram of a d-axis control unit according to an embodiment.

FIG. 8 is a schematic structural diagram of a q-axis control unit according to an embodiment.

10: Renewable energy power supply device 20: Power conversion circuit

24: Controller 30: Mains power supply device

40: Load 210: DC/DC Converter

220: DC/AC converter 230: Output circuit

240: Feedback circuit 250: Detection circuit

252: Second-order digital quadrature converter 254: Arctangent calculation unit

260: Control Module 262: Coordinate Transformation Unit

264: The first controller 266: The second controller

2661: Power compensation unit 2662: D-axis control unit

2663: q-axis control unit 2664: Coordinate inverse conversion unit

2665; operation unit 270: pulse wave regulation circuit

IN1: The first receiving end IN2: The second receiving end

OUT: Load side FB1: The first feedback signal

FB2: The second feedback signal FB3: The third feedback signal

FB4: The fourth feedback signal FB5: The fifth feedback signal

θ _e : Angular position CS1: First control signal

CS2: Second control signal

FB4': The fourth feedback signal expressed in rotor coordinates

FB5': The fifth feedback signal expressed in rotor coordinates

e _α , e _β : sine waves synchronous with mains

d _v1 : the first modulation signal d _v2 : the second modulation signal

ST1: Subtractor ST2: Subtractor

ST3: Subtractor IR1: Current regulator

IR2: Current Regulator VR1: Voltage Regulator

SUM0: totalizer SUM1: first totalizer

SUM2: Second totalizer SUM3: Third totalizer

INV: Inverter MP1: Multiplier

MP2: Multiplier I1: Current command value

I2: current command value V1: voltage command value

e _q : the fifth feedback signal of the q-axis e _d : the fifth feedback signal of the d-axis

CPS: input compensation value μ _d : d-axis control command

μ _q : q-axis control command

ν _αβ : control command expressed in two-axis stator coordinates

i _q : the fourth feedback signal of the q-axis i _d : the fourth feedback signal of the d-axis

WL×i _q : the fourth feedback signal of the q-axis after multiplication

WL×i _d : the fourth feedback signal of the d-axis after multiplication

Detailed ways

In order to further explain the technical means and effects of the present invention to achieve the intended purpose of the invention, the specific implementation methods, methods, steps, features and features of the power conversion circuit proposed according to the present invention will be described below in conjunction with the accompanying drawings and preferred embodiments. Efficacy, detailed as follows.

FIG. 2 is a schematic structural diagram of a power conversion circuit 20 according to the first embodiment of the present invention. FIG. 3 is a schematic structural diagram of a detection circuit 250 according to an embodiment. FIG. 4 is a schematic structural diagram of a control module 260 according to an embodiment.

Please refer to FIG. 2, the power conversion circuit 20 includes a first receiving terminal IN1, a second receiving terminal IN-2, a load terminal OUT, a DC/DC converter 210, a DC/AC converter 220, an output circuit 230, and a feedback circuit 240 , detection circuit 250 , control module 260 and pulse wave regulation circuit 270 .

The first receiving terminal IN1 is electrically connected to the renewable energy power supply device 10 to receive the renewable energy generated by the renewable energy power supply device 10 . The renewable energy power supply device 10 can be a fuel cell, but this is not a limitation of the present invention.

The second receiving end IN- 2 is electrically connected to the supply end of the mains power supply device 30 to receive the mains power provided by the supply end of the mains power supply device 30 .

The load terminal OUT is electrically connected to the load 40 to provide power to the load 40 .

The input end of the DC/DC converter 210 is electrically connected to the first receiving end IN1 , and the output end of the DC/DC converter 210 is electrically connected to the input end of the DC/AC converter 220 . The output end of the DC/AC converter 220 is electrically connected to the output circuit 230 . In addition, the output circuit 230 is also electrically connected to the second receiving terminal IN- 2 and the load terminal OUT.

The feedback circuit 240 is electrically connected to the first receiving terminal IN1 , the output terminal of the DC/DC converter 210 , the output terminal of the DC/AC converter 220 and the second receiving terminal IN_2 . The detection circuit 250 is electrically connected between the feedback circuit 240 and the control module 260 , and the control module 260 is also electrically connected to the feedback circuit 240 . The pulse wave regulation circuit 270 is electrically connected between the control terminal of the DC/DC converter 210 and the control module 260 , and is electrically connected between the control terminal of the DC/AC converter 220 and the control module 260 .

The DC/DC converter 210 boosts the regenerative energy received by the first receiving end IN1 to stable and fixed DC power, and outputs it to the DC/AC converter 220 . Here, the DC/DC converter 210 can convert the output voltage of the renewable energy power supply device 10 received through the first receiving terminal IN1 into a stable DC link voltage corresponding to the duty cycle of the first modulation signal.

The DC/AC converter 220 receives the DC link voltage generated by the DC/DC converter 210 and converts the received DC link voltage into an AC link voltage with a duty cycle corresponding to the second modulation signal.

In a normal state, the output circuit 230 electrically conducts the DC/AC converter 220 and the load terminal OUT, so that the AC link voltage generated by the DC/AC converter 220 is supplied to the load 40 through the load terminal OUT . In other words, when the AC link voltage output by the DC/AC converter 220 is sufficient to supply the load 40 , the output circuit 230 disconnects the electrical connection between the second receiving terminal IN2 and the load terminal OUT. And when the AC link voltage output by the DC/AC converter 220 is not enough to supply the load 40, the output circuit 230 turns on the electrical connection between the second receiving terminal IN2 and the load terminal OUT, so as to supply the mains power. Give load 40.

Wherein, the commercial power may only supply part of the energy that the AC link voltage output by the DC/AC converter 220 does not meet the demand of the load 40 . In other words, when the AC link voltage output by the DC/AC converter 220 is not enough to supply the load 40 , the AC link voltage output by the DC/AC converter 220 and the utility power can jointly share the power demand of the load 40 . However, this is not a limitation of the present invention. When the AC link voltage output by the DC/AC converter 220 is not enough to supply the load 40, the electrical connection between the second receiving terminal IN2 and the load terminal OUT can also be turned on. And the electrical connection between the DC/AC converter 220 and the load terminal OUT is disconnected, so that the power demand of the load 40 can be fully met by the commercial power. Wherein, the output circuit 230 may include a relay.

Here, the feedback circuit 240 can capture the input of the first receiving end IN1, the output of the DC/DC converter 210, the output of the DC/AC converter 220, and the input of the second receiving end IN2, and regenerate the corresponding The first feedback signal FB1 of the output voltage of the energy power supply device 10, the second feedback signal FB2 corresponding to the output current of the regenerative energy power supply device 10, and the third feedback signal corresponding to the DC link voltage of the DC/DC converter 210 FB3, the fourth feedback signal FB4 corresponding to the output current of the DC/AC converter 220 and the fifth feedback signal FB5 corresponding to the output voltage of the mains of the mains power supply device 30 are fed back to the control module 260, And feed back the fifth feedback signal FB5 corresponding to the output voltage of the mains power of the mains power supply device 30 to the detection circuit 250 .

FIG. 3 is a schematic structural diagram of a detection circuit 250 according to an embodiment. Please also refer to FIG. 3 , the detection circuit 250 performs calculations based on the fifth feedback signal FB5 to obtain the angular position θ _e of the commercial power. The detection circuit 250 may include: a second-order digital quadrature converter 252 and an arctangent calculation unit 254 .

The second-order digital quadrature converter 252 is electrically connected between the feedback circuit 240 and the arctangent calculation unit 254 , and the arctangent calculation unit 254 is electrically connected between the second-order digital quadrature converter 252 and the control module 260 .

Here, the second-order digital quadrature converter 252 receives the fifth feedback signal FB5 corresponding to the output voltage of the mains power of the mains power supply device 30 fed back by the feedback circuit 240, and generates Sine waves e _α and e _β synchronous with mains. Then, the arctangent calculation unit 254 calculates the angular position θ _e of the mains by using the sine waves e _α and e _β synchronized with the mains, and outputs the result to the control module 260 . Here, the arctangent calculation unit 254 can calculate the angular position θ _e of the commercial electricity by calculating the arctangent functions of the sine waves e _α , e _β synchronous with the commercial electricity. Among them, the sine waves e _α and e _β are orthogonal, that is, the difference is 90 degrees.

Please refer to FIG. 4 , the control module 260 outputs the first control signal CS1 according to the first feedback signal FB1 , the second feedback signal FB2 and the third feedback signal FB3 . The control module 260 also converts the fourth feedback signal FB4 and the fifth feedback signal FB5 from the two-axis stator coordinates to the rotor coordinates according to the angular position θ _e , and according to the first feedback signal FB1, the second The feedback signal FB2 , the third feedback signal FB3 , the fourth feedback signal FB4 ′ represented by the rotor coordinates, and the fifth feedback signal FB5 ′ represented by the rotor coordinates output the second control signal CS2 .

The control module 260 may include a coordinate transformation unit 262 and two controllers, which are referred to as a first controller 264 and a second controller 266 respectively below for convenience of description.

The input end of the coordinate transformation unit 262 is electrically connected to the feedback circuit 240 and the arctangent calculation unit 254 of the detection circuit 250 . The input end of the first controller 264 is electrically connected to the feedback circuit 240 , and the output end of the first controller 264 is electrically connected to the pulse wave adjustment circuit 270 . In other words, the first controller 264 is electrically connected between the feedback circuit 240 and the pulse wave regulation circuit 270 . The input end of the second controller 266 is electrically connected to the feedback circuit 240, the arctangent calculation unit 254 and the coordinate conversion unit 262 of the detection circuit 250, and the output end of the second controller 266 is electrically connected to the pulse wave adjustment circuit. 270.

The first controller 264 is based on the first feedback signal FB1 corresponding to the output voltage of the renewable energy power supply device 10 , the second feedback signal FB2 corresponding to the output current of the renewable energy power supply device 10 The third feedback signal FB3 of the DC link voltage controls the pulse regulation circuit 270 so that the DC/DC converter 210 outputs stable and fixed DC power. Here, the first controller 264 is based on the first feedback signal FB1 corresponding to the output voltage of the renewable energy power supply device 10 , the second feedback signal FB2 corresponding to the output current of the renewable energy power supply device 10 , and the corresponding DC/DC The third feedback signal FB3 of the DC link voltage of the converter 210 calculates the first control signal CS1 and outputs the first control signal CS1 to the pulse regulation circuit 270 . Therefore, the pulse regulating circuit 270 outputs the first modulation signal d _v1 according to the first control signal CS1, so that the DC/DC converter 210 outputs stable and fixed DC power with a duty cycle corresponding to the first modulation signal d _v1 .

The coordinate conversion unit 262 receives the angular position θ _e of the commercial power calculated by the arctangent calculation unit 254 , and converts the fourth feedback signal FB4 and the fifth feedback signal FB5 from the two-axis rotor coordinates according to the received angular position θ _e (α-β axis coordinates) indicates conversion to stator coordinates (dq axis coordinates).

The second controller 266 receives the first feedback signal FB1, the second feedback signal FB1, the third feedback signal FB3, the fourth feedback signal FB4' and the fifth feedback signal FB5' represented by stator coordinates, and the angular position θ _e , and according to the received feedback signals (namely, the first feedback signal FB1, the second feedback signal FB1, the third feedback signal FB3 and the fourth feedback signal FB4' expressed in stator coordinates and the first The five feedback signals FB5') and the angular position _θe control the pulse wave regulating circuit 270, so that the DC/AC converter 220 outputs AC power with a frequency synchronous with the commercial power. Here, the second controller 266 according to the first feedback signal FB1, the second feedback signal FB1, the third feedback signal FB3, the fourth feedback signal FB4' and the fifth feedback signal FB5' represented by stator coordinates And the angular position θ _e calculates the second control signal CS2 and outputs the second control signal CS2 to the pulse wave adjustment circuit 270 . Therefore, the pulse wave regulating circuit 270 outputs the second modulation signal d _v2 according to the second control signal CS2, so that the DC/AC converter 220 outputs a frequency corresponding to the duty cycle of the second modulation signal d _v2 which is the same as that of the commercial power. Synchronized AC power.

In addition, the control module 260 may further include a controller to control the switching action of the output circuit 230 according to the power demand of the load 40 . Furthermore, the control module 260 can also control the switching action of the output circuit 230 according to the power demand of the load 40 . Since the switching control of the output circuit 230 by the control module 260 is well known to those skilled in the art, it will not be repeated here.

As shown in FIG. 2 , the pulse adjustment circuit 270 can output the first modulation signal d _v1 according to the first control signal CS1 to adjust the duty cycle of the DC/DC converter 210 . Moreover, the pulse regulation circuit 270 can also output a second modulation signal d _v2 according to the second control signal CS2 to adjust the duty cycle of the DC/AC converter 220 .

FIG. 5 is a schematic structural diagram of the first controller 264 according to an embodiment.

Referring to FIG. 5 , the first controller 264 may include a subtractor ST1 , a current regulator IR1 , a totalizer SUM0 and an invertor INV.

The positive input terminal of the subtractor ST1 is electrically connected to the first supply unit (not shown in the figure), and the negative input terminal of the subtractor ST1 is electrically connected to the feedback circuit 240 . The current regulator IR1 is electrically connected to the output terminal of the subtractor ST1 and the first positive input terminal of the summer SUM0. The second positive input end and the negative input end of the summator SUM0 are electrically connected to the feedback circuit 240 , and the output end of the summator SUM0 is electrically connected to the input end of the reciprocator INV. Moreover, the output end of the reciprocator INV is electrically connected to the pulse wave adjustment circuit 270 .

The first supply unit can provide the preset current command value I1 to the subtractor ST1. The subtractor ST1 then subtracts the received current command value I1 from the second feedback signal FB2 , and outputs the subtracted result to the current regulator IR1 . Next, the current regulator IR1 adjusts the output value of the subtractor ST1 (ie, the subtraction result of the current command value I1 and the second feedback signal FB2 ), and outputs the adjusted value to the summer SUM0 . Here, the current regulator IR1 can amplify the error of the input current (ie, the output current of the regenerative energy power supply device). The summator SUM0 adds the output value of the current regulator IR1 to the third feedback signal FB3 and subtracts the first feedback signal FB1 , and outputs the calculation result to the reciprocator INV. Then, the reciprocator INV converts the third feedback signal FB3 into an reciprocal according to the output value of the summer SUM0 , so as to generate the first control signal CS1 to the pulse wave adjustment circuit 270 . Here, the reciprocal unit INV can reduce the DC link voltage of the DC/DC converter 210 by performing the reciprocal operation, so as to normalize the DC link voltage of the DC/DC converter 210 .

FIG. 6 is a schematic structural diagram of the second controller 266 according to an embodiment.

Referring to FIG. 6 , the second controller 266 may include a power compensation unit 2661 , a d-axis control unit 2662 , a q-axis control unit 2663 , a coordinate inversion conversion unit 2664 and a calculation unit 2665 .

The power compensation unit 2661 is electrically connected to the feedback circuit 240 , the coordinate conversion unit 262 and the d-axis control unit 2662 . The d-axis control unit 2662 is also electrically connected to the feedback circuit 240 , the coordinate conversion unit 262 and the coordinate inverse conversion unit 2664 . The q-axis control unit 2663 is electrically connected to the coordinate conversion unit 262 and the coordinate inverse conversion unit 2664 . The coordinate inverse conversion unit 2664 is also electrically connected to the arctangent calculation unit 254 and the calculation unit 2665 of the detection circuit 250 . Moreover, the calculation unit 2665 is electrically connected between the coordinate inverse conversion unit 2664 and the pulse wave adjustment circuit 270 .

Here, the fifth feedback signal FB' represented by the stator coordinates includes the q-axis fifth feedback signal e _q (that is, the quadrature axis component of the fifth feedback signal represented by the stator coordinates) and the d-axis fifth feedback signal No. _ed (that is, the direct-axis component of the fifth feedback signal expressed in stator coordinates).

The power compensation unit 2661 generates an input compensation value _CPS to the d-axis control unit 2662 according to the first feedback signal FB1 , the second feedback signal FB2 and the fifth d-axis feedback signal ed. The d-axis control unit 2662 then generates a d-axis control command _{μ d to} coordinate Inverse conversion unit 2664. Moreover, the q-axis control unit 2663 also generates a q-axis control command μ _q to the coordinate inversion unit 2664 according to the fourth feedback signal FB4 ′ represented by stator coordinates and the fifth q-axis feedback signal e _q . Next, the coordinate inversion unit 2664 _converts the d-axis control command μ _d and the q-axis control command μ _q from the stator coordinates to the two-axis rotor coordinates according to the angular position θ e to generate control commands expressed in two-axis rotor coordinates _ναβ . The computing unit 2665 receives the control command ν _αβ represented by the two-axis rotor coordinates, and generates the second control signal CS2 to the pulse wave regulating circuit 270 by computing the control command ν _αβ represented by the two-axis rotor coordinates.

Wherein, the power compensation unit 2661 can execute the following calculation formula: 2×FB1×FB2÷e _d (Formula 1), and the calculation result of Formula 1 corresponds to the input compensation value CPS.

(公式2)，并且公式2的运算结果相应于第二控制信号CS2。In addition, the control command ν _αβ expressed in two-axis rotor coordinates may include an α-axis control command ν _α and a β-axis control command νβ. The calculation unit 2665 can execute the following calculation formula according to the α-axis control command ν _α and the β-axis control command ν _β :

(Formula 2), and the operation result of Formula 2 corresponds to the second control signal CS2.

Here, the fourth feedback signal FB4' represented by the stator coordinates also includes the q-axis fourth feedback signal i _q (that is, the quadrature axis component of the fourth feedback signal represented by the stator coordinates) and the d-axis fourth feedback signal iq. The feedback signal _id (that is, the direct-axis component of the fourth feedback signal expressed in stator coordinates).

FIG. 7 is a schematic structural diagram of a d-axis control unit 2662 according to an embodiment.

Referring to the figure, the d-axis control unit 2662 may include a subtractor ST2, a voltage regulator VR1, a first summer SUM1, a current regulator IR2, a multiplier MP1 and a second summer SUM2.

The positive input terminal of the subtractor ST2 is electrically connected to the feedback circuit 240 , and the negative input terminal of the subtractor ST2 is electrically connected to the second supply unit (not shown in the figure). The voltage regulator VR1 is electrically connected between the output terminal of the subtractor ST2 and the first positive input terminal of the first summer SUM1. The second positive input terminal of the first totalizer SUM1 is a power compensation unit 2661 , and the negative input terminal of the first totalizer SUM1 is electrically connected to the coordinate transformation unit 262 . The current regulator IR2 is electrically connected between the output terminal of the first summer SUM1 and the first positive input terminal of the second summer SUM2 . The multiplier MP1 is electrically connected between the coordinate transformation unit 262 and the second positive input terminal of the second totalizer SUM2. The negative input terminal of the second totalizer SUM2 is electrically connected to the coordinate transformation unit 262 , and the output terminal of the second totalizer SUM2 is electrically connected to the coordinate inverse transformation unit 2664 .

The second supply unit provides the preset voltage command value V1 to the subtractor ST2. The subtractor ST2 subtracts the third feedback signal FB3 from the feedback circuit 240 from the voltage command value V1, and outputs the result of the subtraction to the voltage regulator VR1. Next, the voltage regulator VR1 adjusts the output value of the subtractor ST2 (ie, the subtraction result of the third feedback signal FB3 and the voltage command value V1 ), and outputs the adjusted value to the first summer SUM1 . Here, the voltage regulator VR1 can amplify the error of the DC link voltage (ie, the output voltage of the DC/DC converter 210 ). The first totalizer SUM1 adds the output value of the voltage regulator VR1 to the input compensation value CPS, then subtracts _the d-axis fourth feedback signal id , and outputs the final calculation result to the current regulator IR2. Next, the current regulator IR2 adjusts the output value of the first totalizer SUM1 (that is, the output value of the voltage regulator VR1 plus the input compensation value CPS, and then subtracts the total result of the _d -axis fourth feedback signal id ), and output the adjusted value to the second totalizer SUM2. Here, the current regulator IR2 can amplify the error of the d-axis fourth feedback signal. Furthermore, the multiplier MP1 multiplies the q-axis fourth feedback signal i _q according to a specific multiplying factor (WL) to output the multiplied q-axis fourth feedback signal WL×i _q to the second summer SUM2 . Then, the second totalizer SUM2 generates the d-axis control command by adding the output value of the current regulator IR2 to the output value of the multiplier MP1 (WL×i _q ) and subtracting the _d- axis fifth feedback signal ed μ _d is given to the coordinate inverse conversion unit 2664.

FIG. 8 is a schematic structural diagram of a q-axis control unit 2663 according to an embodiment.

Referring to FIG. 8 , the q-axis control unit 2663 may include a subtractor ST3 , a current regulator IR3 , a multiplier MP2 and a third summer SUM3 .

The positive input terminal of the subtractor ST3 is electrically connected to a third supply unit (not shown in the figure), and the negative input terminal of the subtractor ST3 is electrically connected to the coordinate conversion unit 262 . The current regulator IR3 is electrically connected between the output terminal of the subtractor ST3 and the first positive input terminal of the third summer SUM3. The multiplier MP1 is electrically connected between the coordinate conversion unit 262 and the second positive input terminal of the third totalizer SUM3. Furthermore, the third positive input terminal of the third totalizer SUM3 is electrically connected to the coordinate conversion unit 262 , and the output terminal of the third totalizer SUM3 is electrically connected to the coordinate inverse conversion unit 2664 .

The third supply unit provides the preset current command value I2 to the subtractor ST3. The subtractor ST3 subtracts the received current command value I2 from the q-axis fourth feedback signal _iq from the coordinate conversion unit 262, and outputs the subtraction result to the current regulator IR3. Next, the current regulator IR3 adjusts the output value of the subtractor ST3 (that is, the subtraction result of the current command value I2 and the _q -axis fourth feedback signal iq), and outputs the adjusted value to the third totalizer SUM3 . Here, the current regulator IR3 can amplify the error of the q-axis fourth feedback signal. Furthermore, the multiplier MP2 multiplies the d-axis fourth feedback signal _id according to a specific multiplying factor (WL), so as to output the multiplied d-axis fourth feedback signal WL× _id to the third summer SUM3. Then, the third totalizer SUM3 generates the q-axis control command μ _q by adding the output value of the current regulator IR3, the output value (WL× _id ) of the multiplier MP2 and the fifth feedback signal e _q of the q-axis to the coordinate inverse conversion unit 2664.

Wherein, the current command value I2 can generally be set to be zero. Furthermore, the two multipliers MP1 and MP2 can use the same specific multiplier, and the specific multiplier (WL) can be the angular frequency of the commercial power (ω _e ) multiplied by the filter inductance value (L _f ).

Furthermore, each component of the control module 260 can realize the above-mentioned corresponding operations through software program design, so as to greatly reduce the size of the hardware circuit.

The power conversion circuit according to the embodiment of the present invention can be applied to a mains parallel regenerative energy system. In terms of control, the mains parallel renewable energy system adopts a two-stage series mode (meaning that the renewable energy generated by the renewable energy power supply device 10 passes through the DC/DC converter 210, and then is connected in series with a first-stage DC/AC Inverter 220). Moreover, in terms of overall system control, the power conversion circuit according to the embodiment of the present invention adopts current closed-loop control in terms of the DC/DC converter 210, so as to feed back the output voltage and output current of the renewable energy power supply device 10 and the DC The link voltage is used to control the amount of power generated by the DC/DC converter 210 . Moreover, in terms of the DC/AC converter 220 in the power conversion circuit according to the embodiment of the present invention, the DC link voltage is fed back to stabilize the DC link voltage; the dq axis coordinate transformation is used to reduce system control design problems ; use the input power compensation control to adjust the DC link voltage, so that the output DC link voltage will not have a huge change in the case of an instantaneous change in the load 40, so as to improve its stability; and use the utility voltage angle The position θ _e is detected to ensure that the output voltage of the DC/AC converter 220 can be synchronized with the mains.

Above-mentioned each embodiment is in order to illustrate the feature of the present invention, and its purpose is to make those skilled in the art understand the content of the present invention and implement according to it, rather than limit the patent scope of the present invention, so all other do not depart from the disclosure of the present invention Equivalent modifications or modifications completed in accordance with the spirit of the invention should still be included in the scope of the patent application described below.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, may use the technical content disclosed above to make some changes or modify them into equivalent embodiments with equivalent changes, but as long as they do not depart from the technical solution of the present invention, the Technical Essence Any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solution of the present invention.

Claims (7)

1. A power conversion circuit, characterized in that it comprises: a first receiving end, used for electrically connecting a renewable energy power supply device; a second receiving end, used to receive a commercial power; a load terminal for electrically connecting a load; A DC/DC converter, the input end of the DC/DC converter is electrically connected to the first receiving end, so as to convert the output voltage of the renewable energy power supply device to a stable value corresponding to the duty cycle of a first modulation signal A DC link voltage of ; a DC/AC converter, the input terminal of the DC/AC converter is electrically connected to the output terminal of the DC/DC converter to receive the DC link voltage and operate corresponding to a second modulation signal periodically converting the DC link voltage into an AC link voltage; an output circuit electrically connected to the output terminal of the DC/AC converter, the second receiving terminal and the load terminal, so as to supply the load with power from one of the AC link voltage and the commercial power; A feedback circuit, electrically connected to the first receiving end, the output end of the DC/DC converter, the output end of the DC/AC converter, and the second receiving end, for feedback corresponding to the regenerative A first feedback signal of the output voltage of the energy power supply device, a second feedback signal corresponding to the output current of the renewable energy power supply device, a third feedback signal corresponding to the DC link voltage of the DC/DC converter the feedback signal, a fourth feedback signal corresponding to the output current of the DC/AC converter, and a fifth feedback signal corresponding to the output voltage of the commercial power; A detection circuit, electrically connected to the feedback circuit, to receive the fifth feedback signal and perform calculation based on the fifth feedback signal to obtain a corner position of the mains; A control module, electrically connected to the feedback circuit and the detection circuit, to convert the fourth feedback signal and the fifth feedback signal from two-axis stator coordinates to rotor coordinates according to the angular position , outputting a first control signal according to the first feedback signal, the second feedback signal, and the third feedback signal, and outputting a first control signal according to the first feedback signal, the second feedback signal, and the third feedback signal number and the fourth feedback signal and the fifth feedback signal represented by the rotor coordinates output a second control signal; and A pulse wave adjustment circuit is electrically connected to the control module, and is used for outputting the first modulation signal according to the first control signal, and outputting the second modulation signal according to the second control signal. 2. The power conversion circuit according to claim 1, wherein the detection circuit comprises: a second-order digital quadrature converter, electrically connected to the feedback circuit, to receive the fifth feedback signal and generate a sine wave synchronous with the mains; and An arctangent calculation unit is electrically connected between the second-order digital quadrature converter and the control module, so as to calculate the angular position of the commercial power by the sine wave synchronized with the commercial power. 3. The power conversion circuit according to claim 1, wherein the control module comprises: a coordinate conversion unit, used for converting the fourth feedback signal and the fifth feedback signal from two-axis rotor coordinates to stator coordinates according to the angular position; a first controller, configured to output the first control signal according to the first feedback signal, the second feedback signal and the third feedback signal; and a second controller, used for according to the first feedback signal, the second feedback signal, the third feedback signal, the fourth feedback signal and the fifth feedback signal represented by the stator coordinates and The angular position outputs the second control signal. 4. The power conversion circuit according to claim 3, wherein the first controller comprises: a subtractor, used for subtracting a current command value from the second feedback signal; a current regulator, used to adjust the output value of the subtractor; an adder, used for adding the output value of the current regulator to the third feedback signal and subtracting the first feedback signal; and A reciprocator is used for converting the third feedback signal into a reciprocal according to the output value of the adder to generate the first control signal. 5. The power conversion circuit according to claim 3, wherein the fifth feedback signal represented by the stator coordinates includes a q-axis fifth feedback signal and a d-axis fifth feedback signal, and the fifth Two controllers include: a power compensation unit, configured to generate an input compensation value according to the first feedback signal, the second feedback signal and the d-axis fifth feedback signal; a d-axis control unit, configured to generate a d-axis control command according to the third feedback signal, the input compensation value, the fourth feedback signal represented by the stator coordinates, and the fifth d-axis feedback signal; a q-axis control unit, configured to generate a q-axis control command according to the fourth feedback signal represented by the stator coordinates and the fifth q-axis feedback signal; a coordinate inverse conversion unit for converting the d-axis control command and the q-axis control command from the stator coordinate representation to the two-axis rotor coordinate representation according to the angular position to generate a two-axis rotor coordinate representation control commands; and An operation unit is used for receiving the control command represented by the two-axis rotor coordinates and performing calculation according to the control command represented by the two-axis rotor coordinates to generate the second control signal. 6. The power conversion circuit according to claim 5, wherein the fourth feedback signal represented by the stator coordinates includes a q-axis fourth feedback signal and a d-axis fourth feedback signal, and the d The axis control unit consists of: a subtractor, used for subtracting the third feedback signal from a voltage command value; a voltage regulator for adjusting the output value of the subtractor; a first totalizer, used to add the output value of the voltage regulator to the input compensation value, and then subtract the d-axis fourth feedback signal; a current regulator, used to adjust the output value of the first totalizer; a multiplier, used to multiply the q-axis fourth feedback signal according to a specific magnification; and A second adder is used for generating the d-axis control command by adding the output value of the current regulator to the output value of the multiplier and subtracting the d-axis fifth feedback signal. 7. The power conversion circuit according to claim 5, wherein the fourth feedback signal represented by the stator coordinates includes a q-axis fourth feedback signal and a d-axis fourth feedback signal, and the q The axis control unit consists of: A subtractor, used to subtract a current command value from the fourth feedback signal of the q-axis; a current regulator, used to adjust the output value of the subtractor; a multiplier, used to multiply the d-axis fourth feedback signal according to a specific ratio; and A third adder is used for generating the q-axis control command by adding the output value of the current regulator, the output value of the multiplier and the q-axis fifth feedback signal.

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