Power supply circuit suitable for three-phase power, and power factor correction method

Abstract

The present disclosure belongs to the technical field of power supplies. Provided are a power supply circuit suitable for three-phase power, and a power factor correction method. The power supply circuit comprises three single-stage power circuits, wherein input ends of the three single-stage power circuits are respectively configured to receive three line voltages / phase voltages of a three-phase alternating-current system, and output ends of the three single-stage power circuits are connected in parallel. The power supply circuit provided in the present disclosure achieves low cost, high efficiency, simple control, and easy expansion.

Description

Power supply circuits and power factor correction methods applicable to three-phase electricity Technical Field

[0001] This disclosure belongs to the field of power supply technology, specifically relating to a power supply circuit and power correction method suitable for three-phase power. Background Technology

[0002] With the development of new energy electric vehicles, charging piles are becoming increasingly common. High-power fast charging piles typically use three-phase AC input for power supply. Common three-phase AC input power conversion topologies generally adopt a two-stage architecture, including power factor correction (PFC) and a DC-DC converter.

[0003] However, using a two-level architecture to achieve power conversion and transmission requires more components and more complex circuit connections, resulting in problems such as high cost, large energy loss, poor stability, low conversion rate, and poor scalability. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art, and to provide a low-cost, high-efficiency, and simple-to-control power supply circuit and power factor control method suitable for three-phase electricity.

[0005] To achieve the above objectives, in a first aspect, embodiments of this disclosure provide a power supply circuit suitable for three-phase electricity, the power supply circuit including three single-stage power circuits, the input terminals of the three single-stage power circuits being respectively configured to receive three line voltages / phase voltages of a three-phase AC power system, and the output terminals of the three single-stage power circuits being connected in parallel.

[0006] In some embodiments, the input terminals of the three single-stage power circuits are respectively connected to phases AB, BC, and AC of a three-phase AC power system.

[0007] In some embodiments, the input terminals of the three single-stage power circuits are respectively connected to phase A and neutral line, phase B and neutral line, and phase C and neutral line of a three-phase AC power system.

[0008] In some embodiments, each of the single-stage power circuits includes a rectifier circuit and a power conversion circuit, wherein the rectifier circuit is configured to receive the line voltage / phase voltage of the three-phase AC system and convert the line voltage / phase voltage into a DC voltage; the power conversion circuit is connected to the output terminal of the rectifier circuit and is configured to perform voltage conversion on the DC voltage so that the output power of the power conversion circuit meets the load requirements.

[0009] In some embodiments, the output terminals of each of the power conversion circuits are connected in parallel.

[0010] In some embodiments, the power conversion circuit includes at least one power conversion sub-circuit, each of the power conversion sub-circuits including an energy storage capacitor, a switching transistor, a transformer, an inductor, and a diode; wherein, a first terminal of the switching transistor is connected to a first output terminal of the rectifier circuit; a second terminal of the switching transistor is connected to a first terminal of a first primary winding of the transformer; a second terminal of the first primary winding of the transformer is connected to a second output terminal of the rectifier circuit; a first terminal of a first secondary winding of the transformer is connected to a first terminal of the energy storage capacitor; a second terminal of the energy storage capacitor is connected to a first terminal of the diode and a first terminal of the inductor; and a second terminal of the first secondary winding of the transformer is connected to a second terminal of the diode.

[0011] In some embodiments, when the power conversion circuit includes at least two power conversion sub-circuits, the output terminals of the at least two power conversion sub-circuits are connected in parallel.

[0012] In some embodiments, the power supply circuit further includes a power factor correction circuit connected to the power conversion circuit. The power factor correction circuit is configured to control the state of the switching transistor based on the input and output parameters of the power conversion circuit, so as to correct the power factor of the power supply circuit.

[0013] In some embodiments, the power factor correction circuit includes a voltage loop, three current loops corresponding to the three single-stage power circuits, and three control circuits, wherein,

[0014] The input terminal of the voltage loop is connected to the output terminal of any of the three single-stage power circuits;

[0015] The output terminal of the voltage loop is connected to the input terminals of the three current loops respectively;

[0016] The input terminal of each current loop is also connected to the first and second output terminals of the rectifier circuit in its corresponding single-stage power circuit.

[0017] The output terminals of the three current loops are respectively connected to the first terminals of the three control circuits;

[0018] The second terminals of the three control circuits are respectively connected to the control terminals of the three switching transistors in the three single-stage power circuits.

[0019] In some embodiments, the voltage loop includes:

[0020] A voltage comparison circuit, connected to the output terminal of any of the three single-stage power circuits, is configured to compare the output voltage of the power conversion circuit with a reference voltage to generate a first comparison result.

[0021] A voltage compensation network, connected to the voltage comparison circuit, is configured to generate a first feedback voltage based on the first comparison result.

[0022] In some embodiments, for each single-stage power circuit, the current loop includes:

[0023] A reference current generation circuit, connected to the output terminal of the voltage compensation network and the second output terminal of the rectifier circuit in the single-stage power circuit, is configured to multiply the first feedback voltage by the input voltage of the power conversion circuit in the single-stage power circuit to obtain the reference current.

[0024] A current comparison circuit, connected to the reference current generation circuit and the first output terminal of the rectifier circuit respectively, is configured to compare the reference current with the input current of the power conversion circuit to generate a second comparison result;

[0025] A current compensation network, connected to the current comparison circuit, is configured to generate a second feedback voltage based on the second comparison result.

[0026] In some embodiments, for each control circuit corresponding to a single-stage power circuit, the first terminal of the control circuit is connected to the current compensation network in the current loop corresponding to the single-stage power circuit, and the second terminal of the control circuit is connected to the control terminal of the switching transistor in the single-stage power circuit, and is configured to control the state of the switching transistor based on the second feedback voltage generated by the current compensation network.

[0027] In some embodiments, for each of the single-stage power circuits,

[0028] The power conversion circuit also includes a resistor, an input capacitor, and an output capacitor; wherein...

[0029] The first terminal of the input capacitor is connected to the second output terminal of the rectifier circuit.

[0030] The second terminal of the input capacitor is connected to the first terminal of the resistor and the first terminal of the switching transistor.

[0031] The second end of the resistor is connected to the first output end of the rectifier circuit;

[0032] The first end of the output capacitor is connected to the second end of the inductor, and the second end of the output capacitor is connected to the second end of the first secondary winding of the transformer.

[0033] In some embodiments, the power factor correction circuit further includes a second secondary winding disposed on the transformer of each of the single-stage power circuits; wherein,

[0034] A control circuit, connected to the switching transistor of the corresponding single-stage power circuit, is set in the second secondary winding of each transformer and configured to detect the voltage of the transformer and output the voltage detection result.

[0035] The control circuit is configured to control the state of the switching transistor based on the voltage detection result and the second feedback voltage.

[0036] In a second aspect, embodiments of this disclosure also provide a method for power factor correction based on a power supply circuit, the method being applied to a power supply circuit as described in any one of the first aspects above, the method comprising:

[0037] Collect the output voltage of any single-stage power circuit, and compare the output voltage with the reference voltage to generate a first comparison result;

[0038] A first feedback voltage is generated based on the first comparison result;

[0039] The first feedback voltage is multiplied by the input voltages of the three single-stage power circuits respectively to obtain three reference currents;

[0040] The three reference currents are compared with the three input currents of the three single-stage power circuits respectively to generate three second comparison results;

[0041] Three second feedback voltages are generated based on the three second comparison results respectively;

[0042] The state of the switching transistors in the three single-stage power circuits is controlled by the three second feedback voltages respectively to correct the power factor of the power supply circuit.

[0043] This disclosure provides a solution for three-phase AC power systems by connecting three single-stage power circuits to the three phases of the system, with the outputs of these three single-stage power circuits connected in parallel. The power supply circuit provided in this disclosure can use a three-phase three-wire AC input, with each of the three line voltages having one or more power conversion sub-circuits, and these multiple power conversion sub-circuits connected in parallel for output. Alternatively, the power supply circuit provided in this disclosure can use a three-phase four-wire AC input, with each of the three phase voltages having one or more power conversion sub-circuits, and these multiple power conversion sub-circuits connected in parallel for output. Furthermore, the power factor correction method provided in this disclosure uses a single voltage loop for all parallel circuits (including the three parallel single-stage power circuits and multiple power conversion sub-circuits connected in parallel within each single-stage power circuit), and each single-stage power circuit has its own current loop. The switching transistors are controlled to conduct when their voltage is at its lowest point. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figures 1A and 1B are schematic diagrams of two three-phase power factor correction topologies provided in the prior art;

[0046] Figures 2A and 2B are schematic diagrams of the topologies of two DC-DC converters provided in the prior art;

[0047] Figure 3 is a structural block diagram of a power supply circuit provided in an embodiment of this disclosure;

[0048] Figure 4 is a circuit diagram of a power supply circuit provided in an embodiment of this disclosure;

[0049] Figure 5 is a circuit diagram of another power supply circuit provided in an embodiment of this disclosure;

[0050] Figure 6 is a circuit diagram of another power supply circuit provided in an embodiment of this disclosure;

[0051] Figure 7 shows the operating waveform of a power supply circuit provided in an embodiment of this disclosure;

[0052] Figure 8 is a block diagram of continuous conduction mode control logic for a single power conversion circuit, as provided in an embodiment of this disclosure.

[0053] Figure 9 is a flowchart of a power factor correction method provided in an embodiment of this disclosure. Detailed Implementation

[0054] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail and completely below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0055] Commonly used two-stage three-phase power factor correction topologies include the three-phase VIENNA (as shown in Figure 1A) and the six-transistor three-bridge-arm circuit (as shown in Figure 1B); commonly used DC-DC converter topologies include the full-bridge LLC circuit (as shown in Figure 2A) and the three-phase LLC circuit (as shown in Figure 2B).

[0056] Referring to Figures 1A-1B and 2A-2B, it can be seen that using a two-level architecture to realize power conversion and transmission requires many components and has complex circuit connections, resulting in problems such as high cost, large energy loss, poor stability, low conversion rate, and poor scalability.

[0057] To address the aforementioned issues with two-stage architectures, this disclosure proposes a single-stage topology for power conversion and transmission. Through a single-stage circuit, power factor correction, electrical isolation, and output voltage and current regulation are simultaneously achieved. The power supply circuit provided by this disclosure is low-cost, highly efficient, simple to control, and easily expandable.

[0058] In a first aspect, embodiments of this disclosure provide a power supply circuit suitable for three-phase electricity.

[0059] Figure 3 is a structural block diagram of a power supply circuit provided in an embodiment of this disclosure. Figure 4 is a circuit diagram of a power supply circuit provided in an embodiment of this disclosure. Figure 5 is a circuit diagram of yet another power supply circuit provided in an embodiment of this disclosure. As shown in Figures 3-5, the power supply circuit includes three single-stage power circuits 1. The input terminals of the three single-stage power circuits 1 are respectively configured to receive the three line voltages / phase voltages of a three-phase AC power system, and the output terminals of the three single-stage power circuits 1 are connected in parallel.

[0060] The power circuit architecture provided in this disclosure consists of three single-stage power circuits 1 connected in parallel. Compared with the two-stage architecture used in the prior art to realize power conversion and transmission, the power circuit provided in this disclosure has a simple circuit connection, low cost, and strong scalability.

[0061] In some embodiments, the input terminals of the three single-stage power circuits 1 are respectively connected to phases AB, BC, and AC of a three-phase AC power system, as shown in Figure 4.

[0062] In some embodiments, the input terminals of the three single-stage power circuits are respectively connected to phase A and neutral line N, phase B and neutral line N, and phase C and neutral line N of a three-phase AC power system, as shown in Figure 5.

[0063] Figure 4 shows a three-phase three-wire circuit diagram, meaning the three-phase AC system has only three lines: three phase lines (A, B, and C), which together form three line voltages. The power supply circuit provided in this disclosure, by employing a three-phase three-wire AC input, can generate significant power and is suitable for high-voltage power transmission and high-power equipment.

[0064] Figure 5 shows a three-phase four-wire circuit diagram, meaning a three-phase AC system has four lines: three phase lines (A, B, C) and one neutral line (N). The three phase lines and the neutral line form three phase voltages. The power supply circuit provided in this disclosure, by adopting a three-phase four-wire AC input, generates relatively low power, making it suitable for low-voltage power supply and providing a safer power supply environment. Furthermore, the neutral line reduces the risk of electric shock and equipment failure.

[0065] The power supply circuit structures in Figure 4 and Figure 5 are basically the same. The only difference is that the input terminals of the three single-stage power circuits 1 in Figure 4 are respectively configured to receive the three line voltages of the three-phase AC system, while the input terminals of the three single-stage power circuits 1 in Figure 5 are respectively configured to receive the three phase voltages of the three-phase AC system.

[0066] The power supply circuit provided in this embodiment can be directly connected to the phase voltage or the line voltage. The specific connection can be flexibly determined according to actual needs, and can meet different application scenarios.

[0067] As shown in Figures 3-5, in some embodiments, each single-stage power circuit 1 includes a rectifier circuit 10 and a power conversion circuit 20. The rectifier circuit 10 is configured to receive the line voltage / phase voltage of the three-phase AC system and convert the line voltage / phase voltage into a DC voltage. The power conversion circuit 20 is connected to the output terminal of the rectifier circuit 10 and is configured to perform voltage conversion on the DC voltage so that the output power of the power conversion circuit 20 meets the load requirements.

[0068] Specifically, each single-stage power circuit 1 includes a corresponding rectifier circuit 10 and a power conversion circuit 20, and each rectifier circuit 10 is connected to its corresponding power conversion circuit 20.

[0069] The rectifier circuit 10 can use a diode rectifier bridge (as shown in Figures 4-5) to convert AC voltage to DC voltage. This configuration simplifies the power supply circuit structure and reduces costs. Of course, the rectifier circuit 10 can also use other structures to convert AC voltage to DC voltage, such as thyristor rectification, MOSFET rectification, etc. This disclosure does not limit this.

[0070] The power conversion circuit 20 is responsible for converting one form of electrical energy into another to meet the specific needs of different electronic devices and loads. Specifically, it controls the electrical energy by controlling the voltage.

[0071] In some embodiments, the output terminals of each of the power conversion circuits 20 are connected in parallel. As shown in Figures 3-5, that is, the output terminals of the three single-stage power circuits are connected in parallel, so that the three output voltages are the same, ensuring that the three-phase output power of the three-phase AC system is the same.

[0072] Figure 6 is a circuit diagram of another power supply circuit provided in an embodiment of this disclosure.

[0073] Referring to Figures 4-6, in some embodiments, the power conversion circuit 20 includes at least one power conversion sub-circuit 21.

[0074] Specifically, in Figures 4 and 5, a power conversion circuit 20 includes only one power conversion sub-circuit 21, while in Figure 6, a power conversion circuit 20 includes multiple power conversion sub-circuits 21. When a power conversion circuit 20 includes multiple power conversion sub-circuits 21, the input terminal of each power conversion sub-circuit 21 is connected to the output terminal of the rectifier circuit 10, and the output terminals of each power conversion sub-circuit 21 are connected in parallel. Increasing the number of power conversion sub-circuits 21 in the power conversion circuit 20 can increase the output power of the single-stage power circuit 1. The specific number of power conversion sub-circuits 21 included in each power conversion circuit 20 can be determined according to the power required by the actual load.

[0075] For ease of description, the following embodiments all use the first single-stage power circuit 1 in Figures 4-6 (the topmost single-stage power circuit 1 in the figures) as an example to describe the structure of the power supply circuit in detail. It can be understood that the other two single-stage power circuits 2 in this power supply circuit have the same structure and working principle as the first single-stage power circuit 1 in Figures 4-6.

[0076] As shown in Figures 4-6, in some embodiments, each of the power conversion sub-circuits 21 includes an energy storage capacitor Cr, a switching transistor Q1, a transformer, an inductor L1, and a diode D1.

[0077] Wherein, the first end of the switching transistor Q1 is connected to the first output end of the rectifier circuit 10; the second end of the switching transistor Q1 is connected to the first end of the first primary winding P of the transformer; the second end of the first primary winding P of the transformer is connected to the second output end of the rectifier circuit 10; the first end of the first secondary winding S1 of the transformer is connected to the first end of the energy storage capacitor Cr; the second end of the energy storage capacitor Cr is connected to the first end of the diode D1 and the first end of the inductor L1; the second end of the first secondary winding S1 of the transformer is connected to the second end of the diode D1.

[0078] Specifically, when switch Q1 is turned on, the excitation current of the transformer increases linearly, diode D1 is turned off, the energy storage capacitor Cr discharges, and the current in inductor L1 increases; when switch Q1 is turned off, diode D1 is turned on, the excitation current of the transformer charges the energy storage capacitor Cr, and at the same time, inductor L1 enters freewheeling mode, and the current decreases. Optionally, diode D1 can also be replaced by a switch, and this disclosure does not limit this.

[0079] This embodiment controls the switching on and off of the switching transistor Q1, thereby controlling the charging and discharging of the energy storage capacitor Cr and the inductor L1, and thus controlling the output power of the three power conversion circuits 20 to meet the load requirements.

[0080] As shown in Figures 4-6, in some embodiments, for each of the single-stage power circuits 1, the power conversion circuit 20 includes not only the energy storage capacitor Cr, the switching transistor Q1, the transformer, the inductor L1 and the diode D1, but also the resistor RCS, the input capacitor C1 and the output capacitor Co1.

[0081] Wherein, the first end of the input capacitor C1 is connected to the second output end of the rectifier circuit 10; the second end of the input capacitor C1 is connected to the first end of the resistor RCS and the first end of the switching transistor Q1; the second end of the resistor RCS is connected to the first output end of the rectifier circuit 10; the first end of the output capacitor Co1 is connected to the second end of the inductor L1, and the second end of the output capacitor Co1 is connected to the second end of the first secondary winding S1 of the transformer.

[0082] Specifically, as shown in Figures 4-6, the input capacitor C1 and the output capacitor Co1 are used to filter the input or output. The resistor Rcs is placed between the rectifier circuit 10 and the input capacitor to detect the input current of the power conversion circuit 20.

[0083] In some embodiments, when the power conversion circuit 20 includes at least two power conversion sub-circuits 21, the output terminals of the at least two power conversion sub-circuits 21 are connected in parallel.

[0084] Specifically, referring to Figures 4-6, in Figures 4 and 5, a power conversion circuit 20 includes only one power conversion sub-circuit 21, while in Figure 6, a power conversion circuit 20 includes multiple power conversion sub-circuits 21. When a power conversion circuit 20 includes multiple power conversion sub-circuits 21, the input terminal of each power conversion sub-circuit 21 is connected to the output terminal of the rectifier circuit 10, and the output terminals of each power conversion sub-circuit 21 are connected in parallel. Increasing the number of power conversion sub-circuits 21 in the power conversion circuit 20 can increase the output power of the single-stage power circuit 1. The specific number of power conversion sub-circuits 21 included in each power conversion circuit 20 can be determined according to the power required by the actual load.

[0085] Among them, for the three power conversion circuits 20 in the three single-stage power circuits 1, each power conversion circuit 20 may include one or more power conversion sub-circuits 21.

[0086] Optionally, the three power conversion circuits 20 in the three single-stage power circuits 1 each include the same number of power conversion sub-circuits 21. This arrangement ensures that the output power of the three phases of the three-phase AC power system is the same.

[0087] The embodiments disclosed herein can meet the application requirements of high power by setting multiple power conversion sub-circuits 21 within the power conversion circuit 20.

[0088] In some embodiments, when a power conversion circuit 20 includes multiple power conversion sub-circuits 21, the power conversion circuit 20 may include only one input capacitor C1 and one output capacitor Co1. The first terminal of the input capacitor C1 is connected to the second output terminal of the rectifier circuit 10, and the second terminal of the input capacitor C1 is connected to the first terminal of the resistor Rcs and the first terminals of the multiple switching transistors Q1 of the multiple power conversion sub-circuits 21. The first terminal of the output capacitor Co1 is connected to the second terminals of the multiple inductors L1 of the multiple power conversion sub-circuits 21, and the second terminal of the output capacitor Co1 is connected to the second terminals of the first secondary windings of the multiple transformers of the multiple power conversion sub-circuits 21. This configuration uses one input capacitor to filter the input of the multiple power conversion sub-circuits 21 and one output capacitor to filter the output of the multiple power conversion sub-circuits 21, resulting in fewer components, a simpler structure, and lower costs.

[0089] In some embodiments, when a power conversion circuit 20 includes multiple power conversion sub-circuits 21, the power conversion circuit 20 may also include multiple input capacitors C1 and multiple output capacitors Co1, each corresponding to a power conversion sub-circuit 21. The first terminals of the multiple input capacitors C1 are all connected to the second output terminal of the rectifier circuit 10, the second terminals of the multiple input capacitors C1 are connected to the first terminal of the resistor Rcs, and the second terminals of the multiple input capacitors C1 are respectively connected to the first terminal of the switching transistor Q1 corresponding to each power conversion sub-circuit 21. The first terminals of the multiple output capacitors Co1 are connected to the second terminal of the inductor L1 corresponding to each power conversion sub-circuit 21, and the second terminals of the output capacitors Co1 are respectively connected to the second terminal of the first secondary winding S1 of the transformer corresponding to each power conversion sub-circuit 21. This configuration allows for better filtering by using one input capacitor C1 to filter the input of one power conversion sub-circuit 21 and one output capacitor Co1 to filter the output of one power conversion sub-circuit 21.

[0090] Of course, for each of the single-stage power circuits 1, the number of input capacitors C1 and output capacitors Co1 in the power conversion circuit 20 can also be greater than 1 and less than the number of power conversion sub-circuits 21 in the power conversion circuit 20. Specifically, depending on the actual scenario, one input capacitor C1 can be used to filter the input of one or more power conversion sub-circuits 21, and one output capacitor Co1 can be used to filter the output of one or more power conversion sub-circuits 21. This disclosure does not impose any restrictions on this.

[0091] Similar to the input capacitor C1 or output capacitor Co1 described above, in some embodiments, the number of resistors Rcs can be set to correspond one-to-one with the number of power conversion sub-circuits 21 in the power conversion circuit 20. Each resistor Rcs is specifically configured to detect the input current of a corresponding power conversion sub-circuit 21. Optionally, the number of resistors Rcs can also be one, specifically configured to detect the total input current of all power conversion sub-circuits 21 in the power conversion circuit 20, which will not be described again.

[0092] It is understandable that, as shown in Figures 4-6, the structure and working principle of the other two single-stage power circuits 1 are similar to those of the single-stage power circuit 1 described above, and will not be repeated here.

[0093] As shown in Figures 3-5, in some embodiments, the power supply circuit includes not only three single-stage power circuits 1, but also a power factor correction circuit 30. The power factor correction circuit 30 is connected to the power conversion circuit 20, and is configured to control the state of the switching transistor based on the input and output parameters of the power conversion circuit 20, so as to correct the power factor of the power supply circuit.

[0094] Specifically, referring to Figures 3-5, the power factor correction circuit 30 can control the state of the three switching transistors (Q1, Q2 and Q3) in the three power conversion circuits 20, so as to control the charging and discharging of the energy storage capacitor Cr and the inductor (L1, L2 or L3) in each power conversion circuit 20, thereby controlling the output power of the power conversion circuit 20.

[0095] The input parameters include at least the input current and input voltage of each power conversion circuit 20, and the output parameters include at least the output current of each power conversion circuit 20.

[0096] As shown in Figures 3-5, in some embodiments, the power factor correction circuit 30 includes a voltage loop 31, three current loops 32 corresponding to the three single-stage power circuits 1, and three control circuits 33.

[0097] The voltage loop 31 is connected to the output of any power conversion circuit 20 in the three single-stage power circuits 1; the output of the voltage loop 31 is connected to the input of the three current loops 32; the input of each current loop 32 is also connected to the first and second outputs of the rectifier circuit 10 in its corresponding single-stage power circuit 1; the outputs of the three current loops 32 are connected to the first terminals of the three control circuits 33; and the second terminals of the three control circuits 33 are connected to the control terminals of the three switching transistors (Q1, Q2, Q3) in the three single-stage power circuits 1.

[0098] Specifically, voltage loop 31 acts on the output side of power conversion circuit 20 to control the output voltage of power conversion circuit 20, so that the output voltage value of power conversion circuit 20 is stabilized at a preset value. Current loop 32 acts on the input side of power conversion circuit 20 to make the input current of power conversion circuit 20 follow the change of input voltage of power conversion circuit 20.

[0099] Although the power supply circuit provided in this disclosure has a three-phase input, the three power conversion circuits 20 are connected in parallel, therefore, the output voltages of the three power conversion circuits 20 are the same. Therefore, this disclosure can use a single voltage loop 31 to simultaneously control the switching transistors in the three power conversion circuits 20. This arrangement simplifies the power supply circuit provided in this disclosure. Of course, the power factor correction circuit 30 can also use three voltage loops 31 connected to the output terminals of the three power conversion circuits 20 respectively; this disclosure does not impose any restrictions on this.

[0100] Since the power supply circuit provided in this disclosure is applied to a three-phase AC system, and the three input currents of the three power conversion circuits 20 are out of phase by 120°, this disclosure requires individual tracking of the input current of each phase. Therefore, this embodiment sets three current loops 32 corresponding to the three power conversion circuits 20 respectively. This setting makes the control of the power conversion circuit 20 by the power factor correction circuit 30 more accurate, and enables the energy storage capacitor Cr and inductor in the power conversion circuit 20 to charge and discharge more accurately according to the power required by the load. Of course, the power factor correction circuit 30 can also use only one current loop 32. In this case, an additional conversion circuit is needed to convert the phase of the current received or output by the current loop 32 to meet the phase difference corresponding to different currents in the three phases and ensure accuracy. This disclosure does not limit the number of current loops 32.

[0101] In some embodiments, the voltage loop 31 includes a voltage comparison circuit and a voltage compensation network.

[0102] As shown in Figures 4 and 5, the voltage comparison circuit is connected to the output terminal of any of the three single-stage power circuits 1, the power conversion circuit 20, and is configured to compare the output voltage V0 of the power conversion circuit 20 with the reference voltage Vref to generate a first comparison result. The voltage compensation network is connected to the voltage comparison circuit and is configured to generate a first feedback voltage VEA based on the first comparison result.

[0103] Specifically, the reference voltage Vref is the voltage required by the load. This reference voltage Vref can be obtained directly from an external input or determined based on an input command; this disclosure does not impose any limitations on this. By comparing the output voltage Vo of the power conversion circuit 20 with the reference voltage Vref, and then compensating the output voltage Vo of the power conversion circuit 20 through a voltage compensation network, a first feedback voltage VEA is formed to keep the output voltage Vo of the power conversion circuit 20 stable.

[0104] As shown in Figures 4 and 5, the voltage comparison circuit can be a comparator or other structures, and this disclosure does not impose any restrictions on it. The voltage compensation network can be a type I compensation network, an SS compensation network, an LCC compensation network, etc., and the specific network can be selected according to the requirements of system stability, response speed, cost, and design complexity, and this disclosure does not impose any restrictions on it.

[0105] In some embodiments, for each single-stage power circuit 1, the current loop 32 includes a reference current generation circuit, a current comparison circuit, and a current compensation network.

[0106] The reference current generation circuit is connected to the output terminal of the voltage compensation network and the second output terminal of the rectifier circuit 10 in the single-stage power circuit 1. It is configured to multiply the first feedback voltage VEA by the input voltage Vin_A of the power conversion circuit 20 in the single-stage power circuit 1 to obtain the reference current Iref_A. The current comparison circuit is connected to both the reference current generation circuit and the first output terminal of the rectifier circuit 10. It is configured to compare the reference current Iref_A with the input current Iin_A of the power conversion circuit 20 to generate a second comparison result. The current compensation network is connected to the current comparison circuit and is configured to generate a second feedback voltage VFB_A based on the second comparison result.

[0107] Specifically, as shown in Figures 4 and 5, the reference current generation circuit can be a multiplier, or other structures. The current comparison circuit can be a comparator, an adder, or other structures. The current compensation network can be a type I current compensation network, a PP compensation network, an LCC compensation network, etc. The choice of current compensation network structure depends on the specific application requirements, system characteristics, and required output characteristics (such as constant current or constant voltage output). Each structure has its specific advantages and limitations, and the selection needs to be based on the actual application scenario during design.

[0108] As shown in Figures 4 and 5, in some embodiments, for each control circuit 33 corresponding to a single-stage power circuit 1, the first terminal of the control circuit 33 is connected to the current compensation network in the current loop 32 corresponding to the single-stage power circuit 1, and the second terminal of the control circuit 33 is connected to the control terminal of the switching transistor (Q1, Q2 or Q3) in the single-stage power circuit 1, and is configured to control the state of the switching transistor (Q1, Q2 or Q3) based on the second feedback voltage generated by the current compensation network.

[0109] Specifically, the control circuit 33 receives the second feedback voltage VFB_A sent by its corresponding current loop 32, calculates the on-time of the corresponding switch, and controls the off-time of the switch to control the charging and discharging of the energy storage capacitor Cr and the inductor L1, so that the power output of the power conversion circuit 20 meets the load requirements.

[0110] As shown in Figures 4 and 5, in some embodiments, the power factor correction circuit 30 further includes a second secondary winding S2 disposed on the transformer of each single-stage power circuit 1; wherein, the second secondary winding S2 disposed on each transformer is connected to a control circuit 33 connected to the corresponding switching transistor (Q1, Q2 or Q3) of the single-stage power circuit 1, and is configured to perform voltage detection on the transformer and output the voltage detection result; the control circuit 33 is configured to control the state of the switching transistor (Q1, Q2 or Q3) based on the voltage detection result and the second feedback voltage VFB_A.

[0111] Specifically, as shown in Figures 4 and 5, the power factor correction circuit 30 is suitable for controlling the power supply circuit in critical conduction mode. The second secondary winding S2 on the transformer of the single-stage power circuit 1 is connected to the control circuit 33, which is connected to the corresponding switching transistor of the single-stage power circuit 1, forming a valley detection circuit. After detecting the valley signal, the control circuit 33 controls the corresponding switching transistor to conduct. This embodiment uses an auxiliary winding for valley detection; however, other structures can also be used for valley detection. This disclosure does not limit the method of valley detection.

[0112] In some embodiments, the control circuit 33 is further configured to receive the input voltage and output voltage of the power conversion circuit 20. Specifically, the control circuit 33 is configured to control the state of the switching transistor based on the input voltage and output voltage of the power conversion circuit 20, the voltage detection result, and the second feedback voltage. That is, in this embodiment of the present disclosure, compared with the embodiments corresponding to FIG4-FIG5, the addition of feedforward in this embodiment of the present disclosure can effectively improve the loop response speed.

[0113] Specifically, by adding feedforward, control circuit 33 needs to sample the input voltage Vin and output voltage Vo of power conversion circuit 20 to calculate the on-time feedforward value Ton_ff of the switching transistor. Then, the on-time Ton of switching transistor Q1 is calculated using Ton_ffy and VFB. The formula for calculating Ton_ff is as follows:

[0114] Where Nps represents the number of power conversion sub-circuits 21 contained in a power conversion circuit 20.

[0115] Figure 7 shows the operating waveforms of a power supply circuit provided in an embodiment of this disclosure. As shown in Figure 7, i_Q1, i_Q2, and i_Q3 represent the currents of the three switching transistors in the three single-stage power circuits 1, respectively; PWM_Q1, PWM_Q2, and PWM_Q3 represent the three control signals output by the three control circuits 33 in the three single-stage power circuits 1, respectively. As can be seen from Figure 7, the currents of the three switching transistors in the three single-stage power conversion circuits are the same in magnitude and 120° out of phase.

[0116] Figure 8 is a control logic block diagram of a continuous conduction mode using a single power conversion circuit 20 as an example, according to an embodiment of this disclosure. The only difference between Figure 8 and the single-stage power circuit 1 in Figures 4-5 is the control circuit 33. In continuous conduction mode, this control circuit receives a fixed-wave triangular wave and the second feedback voltage VFB output from the current loop, generating a PWM control signal to control the state of the switching transistor.

[0117] Among them, the control circuit 33 controls the N power conversion sub-circuits 21 in the power conversion circuit 20 to work in a continuous state, a critical continuous state, or an intermittent state, with their phases interleaved by 360 / N.

[0118] It should be noted that the power factor correction circuit 30 is not shown in the power supply circuit corresponding to Figure 6. However, for the case where a power conversion circuit 20 corresponding to Figure 6 includes multiple power conversion sub-circuits 21, the specific configuration of the power factor correction circuit 30 is similar to the embodiments corresponding to Figures 4-5 above. The power correction circuit 30 still only includes one voltage loop 31, three current loops 32 and three control circuits 33. The specific structure and working principle will not be repeated here.

[0119] The power supply circuit structure provided in this disclosure connects the three phases of a three-phase AC power system to three single-stage power circuits 1, with the outputs of the three single-stage power circuits 1 connected in parallel, making it suitable for three-phase AC power systems. Compared to the two-stage architecture used in the prior art for power conversion and transmission, the power supply circuit provided in this disclosure has a simpler circuit connection, lower cost, and stronger scalability. Furthermore, the power conversion circuit 20 in each single-stage power circuit 1 can also connect multiple power conversion sub-circuits 21 in parallel according to the load requirements, meeting the needs of high-power applications. Furthermore, by employing voltage loops and current loops, power factor control is achieved.

[0120] Secondly, based on the same inventive concept, the present disclosure also provides a power factor correction method.

[0121] Figure 9 is a flowchart of a power factor correction method provided in an embodiment of this disclosure. This method can be applied to the power supply circuit in any of the embodiments of the first aspect described above. As shown in Figure 9, the method specifically includes the following steps:

[0122] S901. Acquire the output voltage Vo of any single-stage power circuit 1, and compare the output voltage Vo with the reference voltage Vref to generate a first comparison result.

[0123] S902. Generate a first feedback voltage VEA based on the first comparison result.

[0124] S903. Multiply the first feedback voltage VEA by the input voltage Vin_A of the three single-stage power circuits 1 respectively to obtain three reference currents Iref_A.

[0125] S904. Compare the three reference currents Iref_A with the three input currents Iin_A of the three single-stage power circuits 1 respectively to generate three second comparison results.

[0126] S905. Generate three second feedback voltages VFB_A based on the three second comparison results respectively.

[0127] S906. Based on the three second feedback voltages VFB_A, the states of the switching transistors in the three single-stage power circuits 1 are controlled respectively to correct the power factor of the power supply circuit.

[0128] In the power factor correction circuit 30 of the power supply circuit, each control circuit 33 detects its own valley signal and controls its corresponding switch (Q1, Q2 or Q3) to turn on. Specifically, in the power factor correction circuit 30 of the power supply circuit, the voltage loop 31 samples the output voltage Vo of any power conversion circuit 20 and compares it with the reference voltage Vref. Then, a first feedback voltage VEA is formed through the voltage feedback compensation network. The first feedback voltage VEA is sent to the three single-stage power circuits 1 respectively, and multiplied with the input voltage (Vin_A, Vin_B, Vin_C) of their respective power conversion circuits 20 to obtain the reference current (Iref_A, Iref_B, and Iref_C). The input current (Iin_A, Iin_B, Iin_C) of their respective power conversion circuits 20 is sampled and compared with the reference current (Iref_A, Iref_B, and Iref_C). A second feedback voltage (VFB_A, VFB_B, and VFB_C) is formed through the current compensation network and sent to their respective control circuits 33. Each control circuit 33 calculates the on-time of the switch and controls the corresponding switch to turn off.

[0129] It is understood that the specific details of the power factor correction method provided in the embodiments of this disclosure can be found in the specific details of the power supply circuit device embodiment of the first aspect described above, and will not be repeated here.

[0130] The solution provided in this disclosure connects the three phases of a three-phase AC power system to three single-stage power circuits 1, with the outputs of the three single-stage power circuits 1 connected in parallel, making it suitable for three-phase AC power systems. Preferably, the power supply circuit provided in this disclosure can use a three-phase three-wire AC input, with each of the three line voltages having one or more power conversion sub-circuits 21, and the multiple power conversion sub-circuits 21 connected in parallel for output. Preferably, the power supply circuit provided in this disclosure can use a three-phase four-wire AC input, with each of the three phase voltages having one or more power conversion sub-circuits 21, and the multiple power conversion sub-circuits 21 connected in parallel for output. Preferably, the power factor correction method provided in this disclosure uses a single voltage loop 31 for all parallel circuits (including the three parallel single-stage power circuits 1, and multiple power conversion sub-circuits 21 connected in parallel within each single-stage power circuit 1), and each single-stage power circuit 1 has its own current loop 32, controlling the switching transistor to conduct when the switching transistor voltage is at its lowest point.

[0131] Compared with existing technologies, the solution provided in this disclosure is low in cost, high in efficiency, simple to control, and easy to expand. Moreover, the secondary current is continuous, and the current ripple flowing through the capacitor is small.

[0132] Thirdly, embodiments of this disclosure also provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method described in any of the second aspects above.

[0133] Fourthly, embodiments of this disclosure also provide a computer-readable storage medium storing a computer program of the method described in any one of the second aspects above.

[0134] Fifthly, embodiments of this disclosure also provide a computer program product, including a computer program / instructions, which, when executed by a processor, implement the steps of the method described in any of the second aspects above.

[0135] Those skilled in the art will understand that embodiments of this disclosure can be provided as methods, systems, or computer program products. Therefore, this disclosure can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this disclosure can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0136] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more flowchart illustrations and / or one or more block diagrams.

[0137] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0138] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0139] This disclosure uses specific embodiments to illustrate the principles and implementation methods of this disclosure. The description of the above embodiments is only for the purpose of helping to understand the methods and core ideas of this disclosure. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this disclosure. Therefore, the content of this specification should not be construed as a limitation of this disclosure.

Claims

1. A power supply circuit suitable for three-phase electricity, characterized in that, The power supply circuit includes three single-stage power circuits. The input terminals of the three single-stage power circuits are respectively configured to receive the three line voltages / phase voltages of the three-phase AC power system, and the output terminals of the three single-stage power circuits are connected in parallel.

2. The power supply circuit according to claim 1, characterized in that, The input terminals of the three single-stage power circuits are respectively connected to phases AB, BC, and AC of the three-phase AC power system.

3. The power supply circuit according to claim 1, characterized in that, The input terminals of the three single-stage power circuits are respectively connected to phase A and neutral line, phase B and neutral line, and phase C and neutral line of the three-phase AC power system.

4. The power supply circuit according to claim 1, characterized in that, Each of the single-stage power circuits includes a rectifier circuit and a power conversion circuit, wherein... The rectifier circuit is configured to receive the line voltage / phase voltage of the three-phase AC system and convert the line voltage / phase voltage into DC voltage. The power conversion circuit is connected to the output terminal of the rectifier circuit and is configured to convert the DC voltage so that the output power of the power conversion circuit meets the load requirements.

5. The power supply circuit according to claim 4, characterized in that, The output terminals of each of the power conversion circuits are connected in parallel.

6. The power supply circuit according to any one of claims 4 or 5, characterized in that, The power conversion circuit includes at least one power conversion sub-circuit, and each power conversion sub-circuit includes an energy storage capacitor, a switching transistor, a transformer, an inductor, and a diode; wherein, The first terminal of the switching transistor is connected to the first output terminal of the rectifier circuit; the second terminal of the switching transistor is connected to the first terminal of the first primary winding of the transformer. The second end of the first primary winding of the transformer is connected to the second output end of the rectifier circuit. The first end of the first secondary winding of the transformer is connected to the first end of the energy storage capacitor, and the second end of the energy storage capacitor is connected to the first end of the diode and the first end of the inductor. The second end of the first secondary winding of the transformer is connected to the second end of the diode.

7. The power supply circuit according to claim 6, characterized in that, When the power conversion circuit includes at least two power conversion sub-circuits, the output terminals of the at least two power conversion sub-circuits are connected in parallel.

8. The power supply circuit according to claim 6, characterized in that, The power supply circuit also includes a power factor correction circuit, which is connected to the power conversion circuit. The power factor correction circuit is configured to control the state of the switching transistor based on the input and output parameters of the power conversion circuit, so as to correct the power factor of the power supply circuit.

9. The power supply circuit according to claim 8, characterized in that, The power factor correction circuit includes a voltage loop, three current loops corresponding to the three single-stage power circuits, and three control circuits. The input terminal of the voltage loop is connected to the output terminal of any of the three single-stage power circuits; The output terminal of the voltage loop is connected to the input terminals of the three current loops respectively; The input terminal of each current loop is also connected to the first and second output terminals of the rectifier circuit in its corresponding single-stage power circuit. The output terminals of the three current loops are respectively connected to the first terminals of the three control circuits; The second terminals of the three control circuits are respectively connected to the control terminals of the three switching transistors in the three single-stage power circuits.

10. The power supply circuit according to claim 9, characterized in that, The voltage loop includes: A voltage comparison circuit, connected to the output terminal of any of the three single-stage power circuits, is configured to compare the output voltage of the power conversion circuit with a reference voltage to generate a first comparison result. A voltage compensation network, connected to the voltage comparison circuit, is configured to generate a first feedback voltage based on the first comparison result.

11. The power supply circuit according to claim 10, characterized in that, For each single-stage power circuit, the current loop includes: A reference current generation circuit, connected to the output terminal of the voltage compensation network and the second output terminal of the rectifier circuit in the single-stage power circuit, is configured to multiply the first feedback voltage by the input voltage of the power conversion circuit in the single-stage power circuit to obtain the reference current. A current comparison circuit, connected to the reference current generation circuit and the first output terminal of the rectifier circuit respectively, is configured to compare the reference current with the input current of the power conversion circuit to generate a second comparison result; A current compensation network, connected to the current comparison circuit, is configured to generate a second feedback voltage based on the second comparison result.

12. The power supply circuit according to claim 11, characterized in that, For each single-stage power circuit, the control circuit has a first terminal connected to the current compensation network in the current loop of the single-stage power circuit, and a second terminal connected to the control terminal of the switching transistor in the single-stage power circuit. The control circuit is configured to control the state of the switching transistor based on the second feedback voltage generated by the current compensation network.

13. The power supply circuit according to claim 12, characterized in that, For each of the aforementioned single-stage power circuits The power conversion circuit also includes a resistor, an input capacitor, and an output capacitor; wherein... The first terminal of the input capacitor is connected to the second output terminal of the rectifier circuit. The second terminal of the input capacitor is connected to the first terminal of the resistor and the first terminal of the switching transistor. The second end of the resistor is connected to the first output end of the rectifier circuit; The first end of the output capacitor is connected to the second end of the inductor, and the second end of the output capacitor is connected to the second end of the first secondary winding of the transformer.

14. The power supply circuit according to claim 13, characterized in that, The power factor correction circuit further includes a second secondary winding disposed on the transformer of each of the single-stage power circuits; wherein, A control circuit, connected to the switching transistor of the corresponding single-stage power circuit, is set in the second secondary winding of each transformer and configured to detect the voltage of the transformer and output the voltage detection result. The control circuit is configured to control the state of the switching transistor based on the voltage detection result and the second feedback voltage.

15. A method for power factor correction based on a power supply circuit, characterized in that, The method is applied to a power supply circuit as described in any one of claims 1 to 14, the method comprising: Collect the output voltage of any single-stage power circuit, and compare the output voltage with the reference voltage to generate a first comparison result; A first feedback voltage is generated based on the first comparison result; The first feedback voltage is multiplied by the input voltages of the three single-stage power circuits respectively to obtain three reference currents; The three reference currents are compared with the three input currents of the three single-stage power circuits respectively to generate three second comparison results; Three second feedback voltages are generated based on the three second comparison results respectively; The state of the switching transistors in the three single-stage power circuits is controlled by the three second feedback voltages respectively to correct the power factor of the power supply circuit.

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