An ac-dc parallel power supply circuit and control method

Abstract

The application discloses an AC-DC parallel power supply circuit and a control method, relates to the technical field of power electronics, and discloses a main circuit comprising a three-phase voltage source, two isolation transformers, two diode rectifier circuits, a triple interleaved parallel Boost conversion circuit, a single-phase inverter circuit and an electrolytic cell load circuit; in the control circuit, a current-voltage double-loop control PI regulation circuit controls a DC output voltage to follow a preset voltage value based on a preset current inner loop control strategy and a preset voltage outer loop control strategy; a control circuit compensation circuit sequentially performs difference processing, sliding average filtering processing and PI control processing on an inverter stage output current with a preset current value to obtain an intermediate current; and a load ripple PWM control circuit controls a load ripple current to follow a preset ripple instruction current based on a preset load ripple control strategy in combination with the intermediate current. The application simultaneously outputs accurate AC ripple and DC current.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to an AC / DC parallel power supply circuit and control method. Background Technology

[0002] In the process of popularizing hydrogen energy, large-scale and low-cost hydrogen production through high-power water electrolyzers necessitates research into the operating characteristics of hydrogen electrolyzers under different power qualities. Therefore, developing test power supplies capable of simulating different power qualities is a key focus for testing electrolyzer characteristics. Several teams have achieved results in researching test power supplies:

[0003] Buitendach et al. studied the impact of different ripple currents on the efficiency of PEM electrolyzers. Their experiments used a programmable power supply, including a signal generator, to output different ripple currents, making their work representative. Albarghot et al. conducted hydrogen electrolysis experiments directly using a small wind turbine in the laboratory, comparing the observed results with those obtained from computer simulations to study load characteristics and prove the correctness of their wind-powered hydrogen production model. Under the premise of meeting the normal power supply requirements of the electrolyzer, Koponen et al. built MW-level converter circuit models and electrolyzer models using 6-pulse and 12-pulse thyristor rectifiers and diode rectifiers. They compared the energy losses of the electrolyzers using these three converters, obtaining the energy loss characteristics of the electrolyzers under different converters. Gilbert studied the impact of high-current ripple on the lifespan and performance of PEMFCs when a DC / DC converter supplying power to the fuel cell experienced an open-circuit fault. To ensure that the test power supply meets the requirement of controllable ripple at the output frequency, the energy feedback unit-based topology of the capacitor current feedback control of the dual PWM inverter by Zheng Zheng and Xu Ben can be referenced. The output terminal of the uncontrolled diode rectifier is modified by replacing it with a controllable switching transistor rectifier bridge. By adopting the corresponding PWM strategy, energy can be fed back to the output side, which is the dual PWM energy feedback topology.

[0004] The above methods all involve modifying the power supply environment of the hydrogen production load to indirectly measure the operating characteristics of the hydrogen electrolyzer load under fluctuating conditions. However, they lack an integrated test power module based on source / grid to simultaneously provide DC current and ripple current to the hydrogen electrolyzer load for testing its operating characteristics, which is insufficient to meet current research needs. Summary of the Invention

[0005] The purpose of this invention is to provide an AC / DC parallel power supply circuit and control method that simultaneously outputs precise AC ripple and DC current, enabling the AC / DC parallel power supply circuit to operate stably and reliably.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] In a first aspect, the present invention provides an AC / DC parallel power supply circuit, comprising a main circuit and a control circuit; the main circuit includes a three-phase voltage source, a first isolation transformer, a second isolation transformer, a first diode rectifier circuit, a second diode rectifier circuit, a triple-interleaved parallel Boost converter circuit, a single-phase inverter circuit, and an electrolytic cell load circuit; the control circuit includes a current and voltage dual-loop control PI regulation circuit, a load ripple PWM control circuit, and a control circuit compensation circuit.

[0008] The first output terminal of the three-phase voltage source is connected to the input terminal of the first diode rectifier circuit through the first isolation transformer. The output terminal of the first diode rectifier circuit is connected to the input terminal of the triple-interleaved parallel Boost converter circuit. The output terminal of the triple-interleaved parallel Boost converter circuit is connected to the electrolytic cell load circuit.

[0009] The second output terminal of the three-phase voltage source is connected to the input terminal of the second diode rectifier circuit through the second isolation transformer. The output terminal of the second diode rectifier circuit is connected to the input terminal of the single-phase inverter circuit. The output terminal of the single-phase inverter circuit is connected to the load circuit of the electrolytic cell.

[0010] The current and voltage dual-loop control PI regulation circuit is used to acquire the DC output voltage of the triple-interleaved parallel Boost converter circuit, and control the DC output voltage to follow the preset voltage value based on the preset current inner loop control strategy and the preset voltage outer loop control strategy.

[0011] The control circuit compensation circuit is used to collect the inverter stage output current of the single-phase inverter circuit, and sequentially perform subtraction processing with a preset current value, moving average filtering processing, and PI control processing on the inverter stage output current to obtain an intermediate current, and then input the intermediate current to the load ripple PWM control circuit.

[0012] The load ripple PWM control circuit is used to collect the load ripple current of the electrolytic cell load circuit, and based on the preset load ripple control strategy, combined with the intermediate current, control the load ripple current to follow the preset ripple command current.

[0013] Optionally, the triple-interleaved parallel Boost converter circuit includes three Boost converter sub-circuits connected in parallel, and the three Boost converter sub-circuits have the same structure; each Boost converter sub-circuit includes a diode, an input-side inductor, a filter capacitor, and an IGBT switch;

[0014] The filter capacitor is connected in series with the diode and then in parallel across the IGBT switch; the IGBT switch is connected in series with the input-side inductor; the input-side inductor is connected to the output terminal of the first diode rectifier circuit, and the filter capacitor is connected to the electrolytic cell load circuit.

[0015] The electrolytic cell load circuit includes a load power supply, a Rohm resistor, a behavior resistor, and a double-layer capacitor; the double-layer capacitor is connected in parallel with the behavior resistor, and the parallel double-layer capacitor and the behavior resistor form a capacitor-resistor branch; the capacitor-resistor branch is connected in series with the Rohm resistor; the Rohm resistor is also connected to the load power supply.

[0016] Optionally, the current-voltage dual-loop control PI regulation circuit includes a first proportional-integral controller, a second proportional-integral controller, a modulator, a duty cycle controller, an inductor current controller, and a first voltage feedback controller; the first voltage feedback controller is used to implement voltage feedback control based on a moving average filtering method.

[0017] The first proportional-integral controller, the second proportional-integral controller, the modulator, the duty cycle controller, and the inductor current controller are connected in sequence;

[0018] The output of the duty cycle controller is also connected to the input of the second proportional-integral controller; the output of the inductor current controller is also connected to the input of the first proportional-integral controller via the first voltage feedback controller.

[0019] Optionally, the load ripple PWM control circuit includes a third proportional-integral controller, a PWM modulator, a first impedance modulator, a second impedance modulator, a load current summer, and a second voltage feedback controller.

[0020] The proportional-integral controller, the PWM modulator, the first impedance modulator, the second impedance modulator, and the load current summer are connected in sequence; the load current summer is used to add the load ripple current output by the second impedance modulator to the acquired load DC current to obtain the load current.

[0021] The output of the load summer is connected to the input of the third proportional-integral controller via the second voltage feedback controller; the input of the second voltage feedback controller is also connected to the output of the second voltage feedback controller, so as to feed back the load ripple current after the moving average filtering process to the third proportional-integral controller.

[0022] The input terminal of the PWM modulator is also connected to the output terminal of the control circuit compensation circuit.

[0023] The first impedance modulator is used to modulate based on the equivalent total impedance of the single-phase inverter circuit; the second impedance modulator is used to modulate based on the AC shunt impedance ratio in the electrolytic cell load circuit.

[0024] Secondly, the present invention provides an AC / DC parallel power supply control method, applied to an AC / DC parallel power supply circuit, the method comprising:

[0025] The DC output voltage of the triple-interleaved parallel Boost converter circuit, the inverter stage output current of the single-phase inverter circuit, and the load ripple current of the electrolytic cell load circuit are collected.

[0026] Based on the preset voltage outer loop control strategy, the current inner loop command current is calculated according to the DC output voltage and the preset voltage value;

[0027] Based on the preset current inner loop control strategy, the actual control voltage is calculated according to the current inner loop command current; the actual control voltage is used to adjust the DC output voltage of the triple-interleaved parallel Boost converter circuit.

[0028] The inverter stage output current is sequentially processed by subtracting from a preset current value, performing a moving average filter, and then PI control to obtain an intermediate current.

[0029] Based on the preset load ripple control strategy, the actual ripple control current is calculated according to the load ripple current, the preset ripple command current and the intermediate current; the actual ripple control current is used to adjust the load ripple current of the electrolytic cell load circuit.

[0030] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0031] This invention discloses an AC / DC parallel power supply circuit and control method. The circuit includes a main circuit and a control circuit. The main circuit consists of a three-phase voltage source, a first isolation transformer, a second isolation transformer, a first diode rectifier circuit, a second diode rectifier circuit, a triple-interleaved parallel Boost converter circuit, a single-phase inverter circuit, and an electrolytic cell load circuit. In the control circuit, a current-voltage dual-loop control PI regulation circuit acquires the DC output voltage of the triple-interleaved parallel Boost converter circuit. Based on a preset current inner-loop control strategy and a preset voltage outer-loop control strategy, the DC output voltage is controlled to follow a preset voltage value, thereby controlling the corresponding DC output current to ensure accurate output DC voltage and DC current. The control circuit compensation circuit acquires the inverter stage output current of the single-phase inverter circuit, and then sequentially performs subtraction with a preset current value, moving average filtering, and PI control processing to obtain an intermediate current. The load ripple PWM control circuit acquires the load ripple current of the electrolytic cell load circuit. Based on a preset load ripple control strategy, combined with the intermediate current, the load ripple current is controlled to follow a preset ripple command current to output accurate AC ripple. Furthermore, through the calculation of the intermediate current and its application in load ripple PWM control, corresponding circuit compensation can be achieved, compensating the DC output of the single-phase inverter circuit to 0, so that it only outputs AC. This invention directly detects and controls the AC ripple component in the load current, enabling the AC ripple component in the load current to track the given command current; simultaneously, it directly detects and controls the DC voltage and DC current in the load current, obtaining accurate DC voltage and DC current, thereby ensuring the stable and reliable operation of the AC / DC parallel power supply circuit. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a topology diagram of the AC / DC parallel power supply circuit of the present invention;

[0034] Figure 2 This is a topology diagram of the Boost converter sub-circuit of the present invention;

[0035] Figure 3 This is a control block diagram of the Boost converter sub-circuit of the present invention;

[0036] Figure 4 This is a block diagram of the current inner loop control of the Boost converter sub-circuit of the present invention;

[0037] Figure 5 This is a block diagram of the voltage outer loop control of the Boost converter sub-circuit of the present invention;

[0038] Figure 6 This is a schematic diagram of the AC / DC parallel power supply circuit of the present invention, which includes a load ripple PWM control circuit and a control circuit compensation circuit.

[0039] Figure 7 This is a schematic diagram of the DC equivalent circuit of the AC / DC parallel power supply circuit of the present invention;

[0040] Figure 8 This is a flowchart illustrating the AC / DC parallel power supply circuit control method of the present invention. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Based on the ripple current output characteristics of the test power supply, this invention proposes a load ripple current detection method based on moving average filtering, and designs a corresponding control strategy based on load ripple current. The load AC ripple current is detected based on moving average filtering, and then the load ripple current control method is used to directly control the ripple component in the load current, ultimately meeting the goal of high-precision AC ripple output.

[0043] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] This invention provides an AC / DC parallel power supply circuit, comprising a main circuit and a control circuit. The main circuit includes a three-phase voltage source, a first isolation transformer T1, a second isolation transformer T2, a first diode rectifier circuit, a second diode rectifier circuit, a triple-interleaved parallel Boost converter circuit, a single-phase inverter circuit, and an electrolytic cell load circuit. The first diode rectifier circuit and the second diode rectifier circuit have the same structure; see details below. Figure 1 .

[0045] like Figure 1As shown, the first output terminal of the three-phase voltage source is connected to the input terminal of the first diode rectifier circuit via a first isolation transformer T1. The output terminal of the first diode rectifier circuit is connected to the input terminal of the triple-interleaved parallel Boost converter circuit, and the output terminal of the triple-interleaved parallel Boost converter circuit is connected to the electrolytic cell load circuit. The second output terminal of the three-phase voltage source is connected to the input terminal of the second diode rectifier circuit via a second isolation transformer T2. The output terminal of the second diode rectifier circuit is connected to the input terminal of the single-phase inverter circuit, and the output terminal of the single-phase inverter circuit is connected to the electrolytic cell load circuit.

[0046] Specifically, the triple-interleaved parallel Boost converter circuit includes three parallel Boost converter sub-circuits, and the three Boost converter sub-circuits have identical structures; moreover, the preset voltage outer loop control strategy and preset current inner loop control strategy corresponding to the three Boost converter sub-circuits are the same. Each Boost converter sub-circuit includes a diode, an input-side inductor, a filter capacitor, and an IGBT switch (corresponding to...). Figure 2 (VT), specifically as follows Figure 2 As shown, and Figure 2 Chinese v d It is a DC voltage source, v dcref i is the DC reference voltage. L V is the inductor current. dc This is the DC output voltage. The triple-interleaved parallel Boost converter circuit uses dual-loop control of voltage and current, with the control objective of making the DC output voltage follow the given value.

[0047] The filter capacitor is connected in series with the diode and then in parallel across the IGBT switch; the IGBT switch is connected in series with the input-side inductor; the input-side inductor is connected to the output terminal of the first diode rectifier circuit; and the filter capacitor is connected to the electrolytic cell load circuit.

[0048] The electrolytic cell load circuit includes a load power supply, a Rohm resistor, a behavior resistor, and a double-layer capacitor; the double-layer capacitor is connected in parallel with the behavior resistor, and the parallel double-layer capacitor and the behavior resistor form a capacitor-resistor branch; the capacitor-resistor branch is connected in series with the Rohm resistor; the Rohm resistor is also connected to the load power supply. Based on Figure 2 A mathematical model of the load impedance of the electrolytic cell load circuit can be established as follows:

[0049]

[0050] Among them, R ohm R represents the resistance value of the ROHM resistor in the load circuit of the electrolytic cell. act C represents the resistance value of the behavioral resistor in the load circuit of the electrolytic cell.dl This indicates the capacitance value of the double-layer capacitor in the load circuit of the electrolytic cell.

[0051] The control circuit includes a current-voltage dual-loop control PI regulation circuit, a load ripple PWM control circuit, and a control circuit compensation circuit. The current-voltage dual-loop control PI regulation circuit acquires the DC output voltage of the triple-interleaved parallel Boost converter circuit and, based on a preset inner current control strategy and a preset outer voltage control strategy, controls the DC output voltage to follow a preset voltage value. The control circuit compensation circuit acquires the inverter stage output current of the single-phase inverter circuit, performs subtraction processing with a preset current value, moving average filtering, and PI control processing on the inverter stage output current sequentially to obtain an intermediate current, and then inputs the intermediate current to the load ripple PWM control circuit. The load ripple PWM control circuit acquires the load ripple current of the electrolytic cell load circuit and, based on a preset load ripple control strategy and the intermediate current, controls the load ripple current to follow a preset ripple command current.

[0052] Specifically, such as Figure 3 As shown, the current-voltage dual-loop control PI regulation circuit includes a first proportional-integral controller, a second proportional-integral controller, a modulator, a duty cycle controller, an inductor current controller, and a first voltage feedback controller; the first voltage feedback controller is used to implement voltage feedback control based on a moving average filtering method.

[0053] The first proportional-integral controller, the second proportional-integral controller, the modulator, the duty cycle controller, and the inductor current controller are connected in sequence; the output terminal of the duty cycle controller is also connected to the input terminal of the second proportional-integral controller; the output terminal of the inductor current controller is also connected to the input terminal of the first proportional-integral controller via the first voltage feedback controller.

[0054] Furthermore, the transfer function of the first proportional-integral controller is:

[0055]

[0056] The transfer function of the second proportional-integral controller is:

[0057]

[0058] The transfer function of the modulator is:

[0059]

[0060] The duty cycle controller controls the duty cycle based on the inductor current. The transfer function of the duty cycle controller is:

[0061]

[0062] The inductor current controller is the output voltage. For inductor current Under the control of the inductor current controller, the transfer function is:

[0063]

[0064] Because the DC-side output needs to respond promptly and quickly to disturbance signals, a moving average filtering method is used in the voltage loop feedback stage. The preset sliding window length T = 20ms, and the transfer function of the first voltage feedback controller is:

[0065]

[0066] Where e represents the natural constant.

[0067] like Figure 4 As shown, the second proportional-integral controller, modulator, and duty cycle controller constitute the inner-loop current control component; as Figure 5 As shown, the first proportional-integral controller, the inductor current controller, the first voltage feedback controller, and the aforementioned Figure 4 The current inner loop control component obtained in the process constitutes the voltage outer loop control component.

[0068] To achieve a small steady-state error and good control characteristics in the converter, a control strategy for the Boost converter circuit is designed. Figure 4 in,i Lref and i L These represent the current command and output current of the current loop, respectively. In a dual-loop control system, the current loop exhibits better stability and a faster dynamic response than the voltage loop. Therefore, in the design of a dual-loop control strategy, the design of the inner current loop controller is prioritized. Figure 3 It can be seen that in the preset inner-loop current control strategy, the open-loop transfer function of the current loop is:

[0069] G 0i (s)=G ci (s)G m (s)G id (s).

[0070] G ci (s), G m (s), G id Substituting the transfer function of (s) into the above open-loop transfer function of the current loop, we can obtain the final open-loop transfer function of the current loop:

[0071]

[0072] M = RohmRactCd1s + Rohm + Ract.

[0073] N = 1 + R act C d1 s.

[0074] The closed-loop transfer function of the current loop is:

[0075]

[0076] Among them, G oi (s) represents the value of the open-loop transfer function of the current loop, V dc V represents the DC output voltage of the Boost converter sub-circuit. m k represents the amplitude of the modulated wave within the modulator. p2 and k i2 All of these represent parameters of the second proportional-integral controller.

[0077] Based on the current loop closed-loop transfer function mentioned above, it can be seen that the highest degree term of its characteristic equation is 4, indicating that its closed-loop transfer function is quite complex. It is difficult to intuitively determine the range of values ​​for the controller parameters that satisfy stability. Therefore, a qualitative analysis method is adopted to analyze the influence of different controller parameters on the zero-pole plot of the current closed-loop transfer function and to approximately determine the range of values ​​for the PI controller parameters.

[0078] Figure 5 In the middle, v dcref and v dc These represent the voltage command and output voltage of the voltage loop, respectively. Substituting the designed inner current loop control strategy, the outer voltage loop is designed. Since the current loop's response speed is much faster than the voltage loop, it can be assumed that the current loop can respond promptly to dynamic changes in the voltage loop, i.e., the current closed-loop gain G... i (s) = 1. From Figure 5 It can be seen that in the preset voltage outer loop control strategy, the voltage loop open-loop transfer function is:

[0079] G ov (s)=G cv (s)G i (s)G vi (s).

[0080] G cv (s), G i (s), G vi Substituting the transfer function of (s) into the above open-loop voltage loop transfer function, we can obtain the final open-loop voltage loop transfer function as follows:

[0081]

[0082] The voltage loop closed-loop transfer function is:

[0083]

[0084] Among them, G ov (s) represents the value of the open-loop transfer function of the voltage loop, D′ represents the duty cycle of the diode in the Boost converter sub-circuit, L represents the value of the input-side inductor in the Boost converter sub-circuit, C represents the value of the filter capacitor in the Boost converter sub-circuit, and G i (s) represents the value of the closed-loop transfer function of the current loop in the preset current inner-loop control strategy, k p1 and k i1 All represent the parameters of the first proportional-integral controller, G v (s) represents the value of the voltage loop closed-loop transfer function, G f (s) represents the value of the transfer function of the first voltage feedback controller.

[0085] In practical applications, the output voltage and output current of the Boost converter sub-circuit are first acquired, and the acquired output voltage and a preset DC reference voltage are input to the above-mentioned... Figure 5 The voltage outer loop control component in the middle obtains a reference current value; the reference current value and the output current are input to the above... Figure 4 The current inner loop control component in the circuit obtains the actual control voltage; the actual control voltage is applied to the switch VT of the Boost converter sub-circuit to adjust the DC output voltage of the Boost converter sub-circuit and at the same time adjust the DC output current of the Boost converter sub-circuit.

[0086] Specifically, such as Figure 6 As shown, the load ripple PWM control circuit includes a third proportional-integral controller, a PWM modulator, a first impedance modulator, a second impedance modulator, a load current summer, and a second voltage feedback controller; in the load ripple PWM control circuit, i lacref For a given ripple instruction, K pwm For the modulation ratio, v ac As the equivalent output voltage source of the inverter stage, L ac For the output-side inductor of the inverter stage, i ac i is the output current of the inverter stage. lac i is the load ripple current output by the second impedance modulator. ldc i represents the DC component of the load current, i.e., the load DC. l Z is the load current. total (s) is the equivalent total impedance of the AC circuit, Z i (s) represents the AC shunt impedance ratio on the load side of the electrolytic hydrogen production process.

[0087] The proportional-integral controller, the PWM modulator, the first impedance modulator, the second impedance modulator, and the load current summer are connected in sequence; the load current summer is used to add the load ripple current output by the second impedance modulator to the acquired load DC current to obtain the load current.

[0088] The output of the load summer is connected to the input of the third proportional-integral controller via the second voltage feedback controller; the input of the second voltage feedback controller is also connected to the output of the second voltage feedback controller, so as to feed back the load ripple current after the moving average filtering process to the third proportional-integral controller.

[0089] Because the output side of the interleaved parallel Boost converter can be equivalent to a DC voltage source when using dual-loop voltage and current control, while the output of the inverter stage can be equivalent to an AC voltage source. However, it is not permissible to connect these two equivalent voltage sources in parallel, as amplitude and phase variations in the AC voltage source will generate extremely large short-circuit currents. Therefore, this invention improves the control method by designing a corresponding control circuit compensation circuit to compensate the DC output of the inverter output branch to zero, outputting only AC quantities.

[0090] Specifically, the input terminal of the PWM modulator is also connected to the output terminal of the control circuit compensation circuit; the control circuit compensation circuit collects the current i output from the single-phase inverter circuit. ac First, with the given instruction i ref The difference between the input and output is 0, and the DC output after moving average filtering is used as feedforward. After PI control, it is added to the output current of the third proportional-integral controller and input to the input of the PWM modulator. Then, it participates in modulation, so that the voltage output of the inverter circuit is equivalent to the DC output voltage v. dc The same DC voltage v I With output AC voltage v ac The sum of, i.e., v dc =v I .

[0091] The first impedance modulator is used to modulate based on the equivalent total impedance of the single-phase inverter circuit; the second impedance modulator is used to modulate based on the AC shunt impedance ratio in the electrolytic cell load circuit.

[0092] The AC / DC parallel power supply circuit of this invention can be equivalent to as follows: Figure 7 The equivalent circuit shown is in which v dc and v I These are two DC voltage sources, and v dc =v IAfter compensation, the short-circuit current caused by voltage error is eliminated. The Boost circuit can normally provide DC voltage and current to the load, and the inverter circuit can accurately output AC ripple current to the load.

[0093] In a specific practical application, the electrolyzer load circuit in the circuit of this invention can be used as an electrolytic hydrogen production device for testing hydrogen electrolysis stacks. It provides DC current and ripple current to the electrolytic hydrogen production load, thereby testing the working characteristics of the hydrogen load.

[0094] In another embodiment, such as Figure 8 As shown, the present invention also provides an AC / DC parallel power supply control method, applied to the AC / DC parallel power supply circuit described above, the method comprising:

[0095] Step 100: Collect the DC output voltage of the triple-interleaved parallel Boost converter circuit, the inverter stage output current of the single-phase inverter circuit, and the load ripple current of the electrolytic cell load circuit.

[0096] Step 200: Based on the preset voltage outer loop control strategy, calculate the current inner loop command current according to the DC output voltage and the preset voltage value.

[0097] Step 300: Based on the preset current inner loop control strategy, calculate the actual control voltage according to the current inner loop command current; the actual control voltage is used to adjust the DC output voltage of the triple-interleaved parallel Boost converter circuit, thereby controlling the DC output current.

[0098] Step 400: The inverter stage output current is sequentially processed by subtracting from a preset current value, performing moving average filtering, and PI control to obtain an intermediate current.

[0099] Step 500: Based on the preset load ripple control strategy, calculate the actual ripple control current according to the load ripple current, the preset ripple command current, and the intermediate current; the actual ripple control current is used to adjust the load ripple current of the electrolytic cell load circuit.

[0100] Compared with the prior art, the present invention also has the following advantages:

[0101] (1) The integrated test power module based on the source / grid of the present invention can simultaneously provide DC current and ripple current to the hydrogen production electrolyzer load, thereby testing the working characteristics of the hydrogen production load.

[0102] (2) Based on the moving average filtering method, this invention obtains the magnitude of the AC ripple component in the load current, and then proposes a control method based on the load ripple current to directly control the ripple component in the load current. The control objective is to make the AC ripple component in the load current track the given command current, and to achieve high-precision output of AC ripple current.

[0103] (3) The present invention outputs precise AC ripple through the load ripple current control method, so that the AC and DC parallel power supply circuit can operate stably and reliably.

[0104] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0105] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An AC / DC parallel power supply circuit, characterized in that, The circuit includes a main circuit and a control circuit; the main circuit includes a three-phase voltage source, a first isolation transformer, a second isolation transformer, a first diode rectifier circuit, a second diode rectifier circuit, a triple-interleaved parallel Boost converter circuit, a single-phase inverter circuit, and an electrolytic cell load circuit; the control circuit includes a current and voltage dual-loop control PI regulation circuit, a load ripple PWM control circuit, and a control circuit compensation circuit. The first output terminal of the three-phase voltage source is connected to the input terminal of the first diode rectifier circuit through the first isolation transformer. The output terminal of the first diode rectifier circuit is connected to the input terminal of the triple-interleaved parallel Boost converter circuit. The output terminal of the triple-interleaved parallel Boost converter circuit is connected to the electrolytic cell load circuit. The second output terminal of the three-phase voltage source is connected to the input terminal of the second diode rectifier circuit through the second isolation transformer. The output terminal of the second diode rectifier circuit is connected to the input terminal of the single-phase inverter circuit. The output terminal of the single-phase inverter circuit is connected to the load circuit of the electrolytic cell. The current and voltage dual-loop control PI regulation circuit is used to acquire the DC output voltage of the triple-interleaved parallel Boost converter circuit, and control the DC output voltage to follow the preset voltage value based on the preset current inner loop control strategy and the preset voltage outer loop control strategy. The control circuit compensation circuit is used to collect the inverter stage output current of the single-phase inverter circuit, and sequentially perform subtraction processing with a preset current value, moving average filtering processing, and PI control processing on the inverter stage output current to obtain an intermediate current, and then input the intermediate current to the load ripple PWM control circuit. The load ripple PWM control circuit is used to collect the load ripple current of the electrolytic cell load circuit, and based on the preset load ripple control strategy, combined with the intermediate current, control the load ripple current to follow the preset ripple command current.

2. The AC / DC parallel power supply circuit according to claim 1, characterized in that, The triple-interleaved parallel Boost converter circuit includes three Boost converter sub-circuits connected in parallel, and the three Boost converter sub-circuits have the same structure; each Boost converter sub-circuit includes a diode, an input-side inductor, a filter capacitor, and an IGBT switch; The filter capacitor is connected in series with the diode and then in parallel across the IGBT switch; the IGBT switch is connected in series with the input-side inductor; the input-side inductor is connected to the output terminal of the first diode rectifier circuit, and the filter capacitor is connected to the electrolytic cell load circuit. The electrolytic cell load circuit includes a load power supply, a Rohm resistor, a behavior resistor, and a double-layer capacitor; the double-layer capacitor is connected in parallel with the behavior resistor, and the parallel double-layer capacitor and the behavior resistor form a capacitor-resistor branch; the capacitor-resistor branch is connected in series with the Rohm resistor; the Rohm resistor is also connected to the load power supply.

3. The AC / DC parallel power supply circuit according to claim 1, characterized in that, The current-voltage dual-loop control PI regulation circuit includes a first proportional-integral controller, a second proportional-integral controller, a modulator, a duty cycle controller, an inductor current controller, and a first voltage feedback controller; the first voltage feedback controller is used to implement voltage feedback control based on a moving average filtering method. The first proportional-integral controller, the second proportional-integral controller, the modulator, the duty cycle controller, and the inductor current controller are connected in sequence; The output of the duty cycle controller is also connected to the input of the second proportional-integral controller; the output of the inductor current controller is also connected to the input of the first proportional-integral controller via the first voltage feedback controller.

4. The AC / DC parallel power supply circuit according to claim 1, characterized in that, The load ripple PWM control circuit includes a third proportional-integral controller, a PWM modulator, a first impedance modulator, a second impedance modulator, a load current summer, and a second voltage feedback controller. The proportional-integral controller, the PWM modulator, the first impedance modulator, the second impedance modulator, and the load current summer are connected in sequence; the load current summer is used to add the load ripple current output by the second impedance modulator to the acquired load DC current to obtain the load current. The output of the load summer is connected to the input of the third proportional-integral controller via the second voltage feedback controller; the input of the second voltage feedback controller is also connected to the output of the second voltage feedback controller, so as to feed back the load ripple current after the moving average filtering process to the third proportional-integral controller. The input terminal of the PWM modulator is also connected to the output terminal of the control circuit compensation circuit. The first impedance modulator is used to modulate based on the equivalent total impedance of the single-phase inverter circuit; the second impedance modulator is used to modulate based on the AC shunt impedance ratio in the electrolytic cell load circuit.

5. A method for controlling AC / DC parallel power supply, applied to the AC / DC parallel power supply circuit according to any one of claims 1-4, characterized in that the method... include: The DC output voltage of the triple-interleaved parallel Boost converter circuit, the inverter stage output current of the single-phase inverter circuit, and the load ripple current of the electrolytic cell load circuit are collected. Based on the preset voltage outer loop control strategy, the current inner loop command current is calculated according to the DC output voltage and the preset voltage value; Based on the preset current inner loop control strategy, the actual control voltage is calculated according to the current inner loop command current; the actual control voltage is used to adjust the DC output voltage of the triple-interleaved parallel Boost converter circuit. The inverter stage output current is sequentially processed by subtracting from a preset current value, performing a moving average filter, and then PI control to obtain an intermediate current. Based on the preset load ripple control strategy, the actual ripple control current is calculated according to the load ripple current, the preset ripple command current and the intermediate current; the actual ripple control current is used to adjust the load ripple current of the electrolytic cell load circuit.

6. The AC / DC parallel power supply control method according to claim 5, characterized in that, The triple-interleaved parallel Boost converter circuit includes three Boost converter sub-circuits, and the preset voltage outer loop control strategy corresponding to the three Boost converter sub-circuits is the same. In the preset voltage outer loop control strategy, the voltage loop open-loop transfer function is: The voltage loop closed-loop transfer function is: Among them, G ov (s) represents the value of the open-loop transfer function of the voltage loop, R ohm R represents the resistance value of the ROHM resistor in the load circuit of the electrolytic cell. act C represents the resistance value of the behavioral resistor in the load circuit of the electrolytic cell. dl The value of the double-layer capacitor in the electrolytic cell load circuit is represented by D′, the duty cycle of the diode in the Boost converter sub-circuit is represented by L, the value of the input-side inductor in the Boost converter sub-circuit is represented by C, and the value of the filter capacitor in the Boost converter sub-circuit is represented by G. i (s) represents the value of the closed-loop transfer function of the current loop in the preset current inner-loop control strategy, k p1 and k i1 All represent the parameters of the first proportional-integral controller, G v (s) represents the value of the voltage loop closed-loop transfer function, G f (s) represents the value of the transfer function of the first voltage feedback controller.

7. The AC / DC parallel power supply control method according to claim 6, characterized in that, The three Boost converter sub-circuits have the same preset current inner loop control strategy; In the preset current inner loop control strategy, the open-loop transfer function of the current loop is: M=R ohm R act C d1 s+R ohm +R act ; N=1+R act C d1 s; The closed-loop transfer function of the current loop is: Among them, G oi (s) represents the value of the open-loop transfer function of the current loop, V dc V represents the DC output voltage of the Boost converter sub-circuit. m k represents the amplitude of the modulated wave within the modulator. p2 and k i2 All of these represent parameters of the second proportional-integral controller.

8. The AC / DC parallel power supply control method according to claim 6, characterized in that, G f The functional formula for (s) is: Where T represents the preset sliding window length, and e represents the natural constant.

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