Three-phase power control circuit

Abstract

Provided in the present application is a three-phase power control circuit. The circuit comprises: a power module, a reactive-power switching module, a first filter module, a rectifier module, a second filter module and a soft-start module, wherein the reactive-power switching module comprises a first switch unit and a second switch unit; the second filter module comprises a first capacitor unit and a second capacitor unit; and the soft-start module comprises a third switching unit, a first diode unit and a second diode unit. By configuring the connection relationship between the power module, the reactive-power switching module, the first filter module, the rectifier module, the second filter module and the soft-start module, and by means of the connection and disconnection of the switch units, the reactive power consumption of the control circuit in a standby mode is eliminated, thereby simplifying operations, reducing costs, and also improving the durability and safety of the control circuit.

Description

A three-phase power supply control circuit

[0001] This application claims priority to Chinese Patent Application No. 202410969191.6, filed on July 19, 2024, entitled “A Three-Phase Power Supply Control Circuit”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of power supply control, specifically to a three-phase power supply control circuit. Background Technology

[0003] In the fields of power electronics and charging equipment, standby reactive power loss has long been a common concern in the industry. In the three-phase power module technology circuit, the three-phase AC input, EMC filter circuit, AC relay switch and soft start circuit are connected in parallel, three-phase Vienna power conversion circuit, DC bus filter circuit, and DC / DC high-frequency isolation circuit are connected in sequence. The magnitude of standby reactive power loss depends on the capacitance of the EMC filter circuit.

[0004] Currently, reactive power loss is generally reduced by selecting low-loss electronic components or reducing the switching frequency. However, this is too costly and complicated to operate. Furthermore, when there are many electronic components, the reduction in reactive power loss accumulates and has a significant negative impact on the safety and durability of the control circuit.

[0005] Summary of the Invention

[0006] This application provides a three-phase power supply control circuit, which sets up the connection relationship between the power supply module, reactive power switching module, first filter module, rectifier module, second filter module and soft starter module. By turning on and off the switching unit, the reactive power consumption of the control circuit in standby mode is eliminated, which not only simplifies operation and reduces cost, but also improves the durability and safety of the control circuit.

[0007] This application provides a three-phase power supply control circuit, including:

[0008] The power supply module, reactive power switching module, first filter module, rectifier module, second filter module, and soft starter module are provided. The reactive power switching module includes a first switching unit and a second switching unit. The second filter module includes a first capacitor unit and a second capacitor unit. The soft starter module includes a third switching unit, a first diode unit, and a second diode unit.

[0009] The first live wire of the power module is connected to the first input terminal of the first filter module; the second live wire of the power module is connected to the first terminal of the first switching unit, the second terminal of the first switching unit is connected to the input side of the first filter module; the third live wire of the power module is connected to the first terminal of the second switching unit, the second terminal of the second switching unit is connected to the second input terminal of the first filter module; the output terminal of the first filter module is connected to the input terminal of the rectifier module, the output terminal of the first filter module corresponds to the input terminal of the rectifier module; the first output terminal of the rectifier module is connected to the first terminal of the first capacitor unit; the second output terminal of the rectifier module is connected to the second terminal of the first capacitor unit. The third output terminal of the current module is connected to the first terminal of the second capacitor unit. The first terminal of the third switch unit is connected to the second live wire or the third live wire. The second terminal of the third switch unit is connected to the first terminal of the first diode unit. The second terminal of the first diode unit is connected to the first terminal of the first capacitor unit. The first terminal of the second diode unit is connected to the second terminal of the third switch unit. The second terminal of the second diode unit is connected to the first terminal of the second capacitor unit. The second terminal of the first capacitor unit is connected to the second terminal of the second capacitor unit. The first terminal of the first diode unit and the second terminal of the second diode unit have the same polarity. The second terminal of the first capacitor unit is connected to ground (GND).

[0010] As can be seen, in this application, the connection relationship between the power supply module, the reactive power switching module, the first filter module, the rectifier module, the second filter module, and the soft starter module is set. By turning the switching unit on and off, the reactive power consumption of the control circuit in standby mode is eliminated, which not only simplifies operation and reduces costs, but also improves the durability and safety of the control circuit. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 is a schematic diagram of an application scenario of a three-phase power supply control circuit provided in an embodiment of this application;

[0013] Figure 2 is a schematic diagram of the composition of a three-phase power supply control circuit provided in an embodiment of this application;

[0014] Figure 3 is a schematic diagram of another three-phase power supply control circuit provided in an embodiment of this application;

[0015] Figure 4 is a schematic diagram of the composition of a line voltage uncontrolled rectifier pre-charging circuit provided in an embodiment of this application;

[0016] Figure 5 is a flowchart illustrating a three-phase power supply control method provided in an embodiment of this application. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0018] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0019] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0020] In the embodiments of this application, "and / or" describes the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone; A and B exist simultaneously; B exists alone. Among them, A and B can be singular or plural.

[0021] In this embodiment, the symbol " / " can indicate that the preceding and following objects are in an "or" relationship. Alternatively, the symbol " / " can also represent a division sign, i.e., performing a division operation. For example, A / B can mean A divided by B.

[0022] In the embodiments of this application, "equal to" can be used with "greater than" and is applicable to technical solutions used when "greater than" is used; it can also be used with "less than" and is applicable to technical solutions used when "less than" is used. When "equal to" is used with "greater than", it is not used with "less than"; when "equal to" is used with "less than", it is not used with "greater than".

[0023] In the fields of power electronics and charging equipment, standby reactive power loss has long been a common concern in the industry. In the three-phase power module technology circuit, the three-phase AC input, EMC filter circuit, AC relay switch and soft start circuit are connected in parallel, three-phase Vienna power conversion circuit, DC bus filter circuit, and DC / DC high-frequency isolation circuit are connected in sequence. The magnitude of standby reactive power loss depends on the capacitance of the EMC filter circuit.

[0024] Currently, reactive power loss is generally reduced by selecting low-loss electronic components or reducing the switching frequency. However, this is too costly and complicated to operate. Furthermore, when there are many electronic components, the reduction in reactive power loss accumulates and has a significant impact on equipment operation.

[0025] To address the aforementioned problems, this application provides a three-phase power supply control circuit. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0026] Please refer to Figure 1, which is a schematic diagram of an application scenario of a three-phase power supply control circuit provided in an embodiment of this application. As shown in Figure 1, the three-phase power supply control circuit may include a three-phase AC input 101, a reactive power switching circuit 102, an EMC filter circuit 103, a three-phase Vienna circuit 104, a DC bus filter circuit 105, a DC / DC high-frequency isolation circuit 106, an electric vehicle 107, and a soft start circuit 108. The three-phase AC input is connected to the input side of the reactive power switching circuit via phases A, B, and C, respectively. The output side of the reactive power switching circuit is connected to the input side of the electromagnetic compatibility (EMC) filter circuit. The output side of the EMC filter circuit is connected to the input side of the three-phase Vienna circuit. The output side of the three-phase Vienna circuit is connected to the input side of the DC bus filter circuit. The output side of the DC bus filter circuit is connected to the input side of the DC / DC high-frequency isolation circuit. The output side of the DC / DC high-frequency isolation circuit is connected to the electric vehicle. The three-phase AC input is also connected to the input side of the soft starter circuit via phase C. The output side of the soft starter circuit is connected to the DC bus filter circuit. The three-phase AC input is also connected to ground via the PE ground wire. This three-phase power control circuit can be applied to the electric vehicle charging field, eliminating reactive power loss during the charging process.

[0027] Please refer to Figure 2, which is a schematic diagram of the composition of a three-phase power supply control circuit provided in an embodiment of this application. As shown in Figure 2, the three-phase power supply control circuit includes a power supply module 201, a reactive power switching module 202, a first filter module 203, a rectifier module 204, a second filter module 205, and a soft starter module 206. The reactive power switching module 202 includes a first switching unit 2021 and a second switching unit 2022. The second filter module 205 includes a first capacitor unit 2051 and a second capacitor unit 2052. The soft starter module 206 includes a third switching unit 2061, a first diode unit 2062, and a second diode unit 2063. The first live wire of the power supply module 201 is connected to the first input terminal of the first filter module 203; the second live wire of the power supply module 201 is connected to the first terminal of the first switching unit 2021, the second terminal of the first switching unit 2021 is connected to the second input terminal of the first filter module 203, the third live wire of the power supply module 201 is connected to the first terminal of the second switching unit 2022, the second terminal of the second switching unit 2022 is connected to the third input terminal of the first filter module 203, and the output terminal of the first filter module 203 is connected to the first input terminal of the first filter module 203. The input terminals of the current module 204 are connected one-to-one. The first output terminal of the rectifier module 204 is connected to the first terminal of the first capacitor unit 2051. The second output terminal of the rectifier module 204 is connected to the second terminal of the first capacitor unit 2051. The third output terminal of the rectifier module 204 is connected to the first terminal of the second capacitor unit 2052. The first terminal of the third switch unit 2061 is connected to the third live wire. The second terminal of the third switch unit 2061 is connected to the first terminal of the first diode unit 2062. The second terminal of the first diode unit 2062 is connected to the first terminal of the first capacitor unit 2051. The first terminal of the second diode unit 2063 is connected to the second terminal of the third switch unit 2061. The second terminal of the second diode unit 2063 is connected to the first terminal of the second capacitor unit 2052. The second terminal of the first capacitor unit 2051 is connected to the second terminal of the second capacitor unit 2052. The first terminal of the first diode unit 2062 and the second terminal of the second diode unit 2063 have the same polarity. The second terminal of the first capacitor unit is connected to ground.

[0028] The power module 201 may include a controller for controlling the on and off of the first switching unit, the second switching unit, and the third switching unit, so that the control circuit can form different loops, simplifying operation, reducing cost, and eliminating reactive power consumption of the control circuit in standby mode, thereby improving the durability and safety of the control circuit.

[0029] Please refer to Figure 3, which is a schematic diagram of another three-phase power control circuit provided in this embodiment of the application. As shown in Figure 3, the three-phase power control circuit may include a grid input 301, a reactive power switching module 202, an EMC filter circuit 103, a three-phase Vienna circuit 104, a bus filter circuit 105, and a pre-charge soft start circuit 108. The grid input 301 may be the three-phase AC input 101 in Figure 1 and / or the power module 201 in Figure 2, and may include a controller for controlling the closing and opening of K1, K2, Ks1, Ks2, and / or Ks. The three-phase input source of the grid input 301 may be a three-phase four-wire input, that is, including phase A, phase B, phase C and ground wire, which are A, B, C and PE in the figure, respectively.

[0030] The first filtering module can be an EMC filter circuit 103, used to eliminate electromagnetic interference signals generated by the control circuit and prevent these signals from adversely affecting the power grid and other equipment. Simultaneously, the EMC filter circuit also protects the control circuit from external electromagnetic interference, ensuring its normal operation. As shown in Figure 3, the EMC filter circuit can include a common-mode inductor Lg and six safety capacitors, namely Cx1, Cx2, Cx3, Cx4, Cx5, and Cx6. The first common-mode inductor is located on phase A, the second on phase B, and the third on phase C. Cx1 and Cx4 are the safety capacitors across the first common-mode inductor; similarly, Cx2 and Cx5 are the safety capacitors across the second common-mode inductor, and Cx3 and Cx4 are the safety capacitors across the third common-mode inductor. Furthermore, one end of Cx1, Cx2, and Cx3 is connected in parallel, and one end of Cx4, Cx5, and Cx6 is also connected in parallel. It should be noted that MEC filter circuits may also include other EMC optimization circuits and devices.

[0031] The rectifier module can be a three-phase Vienna circuit 104, used to convert AC to DC. The three-phase Vienna circuit employs Vienna rectification technology, featuring high efficiency, high power factor, and low harmonics. As shown in Figure 3, the three-phase Vienna circuit can include an input voltage sampling circuit at the input port. This circuit includes six resistors: R1, R2, R3, R4, R5, and R6. R1 and R2 are connected in series and to phase A, R3 and R4 are connected in series and to phase B, and R5 and R6 are connected in series and to phase C. This allows for the acquisition of three-phase input voltage samples: Vasamp, Vbsamp, and Vcsamp. The input terminal of the three-phase Vienna circuit can be connected to the output terminal of the EMC circuit. Input current sampling can be performed, namely Ia_samp, Ib_samp, and Ic_samp; the three-phase Vienna circuit 104 can also include three power inductors, namely L2, L3, and L4, six fast recovery transistors, namely D1, D2, D3, D4, D5, and D6, three active switches and their S1, S2, and S3. Correspondingly, the controller in the power supply module can control the closing and opening of S1, S2, and S3 respectively through drive signals S1_DRV, S2_DRV, and S3_DRV.

[0032] The second filtering module can be a bus filter circuit 105, used to further stabilize the voltage and current of the DC bus by filtering out harmonics and noise on the DC bus. As shown in Figure 3, the bus filter circuit 105 can include an upper bus capacitor Cbus1 and a lower bus capacitor Cbus2. The first capacitor unit can be Cbus1, and the second capacitor unit can be Cbus2. Cbus1 and Cbus2 are connected in series. The first output terminal of the three-phase bus is connected to the first terminal of Cbus1. The second output terminal is connected between Cbus1 and Cbus2 and is connected to ground GND2. The third output terminal is connected to the first terminal of Cbus2. Three voltage values ​​can be obtained, namely, the positive Vbus+ voltage of the entire bus, the negative Vbus- voltage of the entire bus, and the DC bus midpoint voltage Vbus0 (the voltage at the connection point between Cbus1, Cbus2, and GND in Figure 3), where Vbus0 is 0.

[0033] As can be seen, in this example, by setting the connection relationship between the power supply module, reactive power switching module, first filter module, rectifier module, second filter module, and soft starter module, and controlling the conduction or disconnection of the first and second switching units in the reactive power switching module, and the conduction or disconnection of the third switching unit in the soft starter module according to different situations of the power supply module, the cost is reduced, and the reactive power consumption of the control circuit in standby mode is eliminated, thereby improving the durability and safety of the control circuit.

[0034] Specifically, the third switching unit includes a fifth switch and a third resistor. The first end of the third resistor is connected to the third live wire, the second end of the third resistor is connected to the first end of the fifth switch, and the second end of the fifth switch is connected to the first end of the first diode unit. When the third switching unit is turned on, the fifth switch is closed.

[0035] As shown in Figure 3, the pre-charge soft-start circuit 108 may include a pre-charge soft-start resistor Rs, a pre-charge soft-start switch Ks, and two pre-charge soft-start rectifier diodes, namely D11 and D12. The fifth switch can be Ks in Figure 3, and the third resistor can be Rs in Figure 3. It should be noted that since Cbus1 and Cbus2 have large capacitances, when Ks is closed, the current flowing through Cbus1 and Cbus2 will be very large, which may cause Cbus1 and Cbus2 to break down. Therefore, the resistance value of Rs needs to be set to a large value.

[0036] In this way, by closing Rs and Ks, Cbus1 and Cbus2 in the bus filter circuit can be safely charged, so that the reactive power loss of the three-phase power control circuit in this state is almost zero.

[0037] Specifically, the first switching unit includes a first switch, a first resistor, and a second switch. The first end of the first switch is connected to the first end of the first resistor, the second end of the first switch is connected to the first end of the second switch, the second end of the second switch is connected to the second end of the first resistor, the second live wire of the power module is connected to the first end of the first switch, and the second end of the first switch is connected to the second input end of the first filter module.

[0038] The first switching unit can be a main power relay switch circuit connected to the second live wire of the power module, and the first switch can be a relay. As shown in Figure 3, the first switching unit 2021 in the reactive power switching module 202 is connected to the grid input through the B-phase line. The first switching unit 2021 can include a main power relay switch K2, a pre-charge resistor Rs2, and an AC pre-charge switch Ks2. The circuit formed by Rs2 and Ks2 in series is connected in parallel with K2, and the two ends of the parallel circuit are respectively connected to the grid input of the B-phase line and the EMC filter circuit of the B-phase line. The first switch can be K2 in Figure 3, the first resistor can be Rs2 in Figure 3, and the second switch can be Ks2 in Figure 3. It should be noted that when the first switching unit is turned on, in order to reduce the voltage difference across the main power relay switch K2 when it is energized, Ks2 needs to be closed first, and then K2 needs to be closed.

[0039] In this way, the capacitor in the first filter circuit of phase B line is charged through the first switch, the first resistor and the second switch in the first switching unit, avoiding the risk of sticking caused by large voltage difference, simplifying operation, reducing cost, and helping to eliminate the reactive power consumption of the control circuit in standby mode, thus improving the durability and safety of the control circuit.

[0040] Specifically, the second switching unit includes a third switch, a second resistor, and a fourth switch. The first end of the third switch is connected to the first end of the second resistor, the second end of the third switch is connected to the first end of the fourth switch, the second end of the fourth switch is connected to the second end of the second resistor, the second live wire of the power module is connected to the first end of the third switch, and the second end of the third switch is connected to the third input terminal of the first filter module.

[0041] The second switching unit can be a main power relay switch circuit connected to the third live wire of the power module, and the third switch can be a relay. As shown in Figure 3, the second switching unit 2022 in the reactive power switching module 202 is connected to the grid input through the C-phase line. The second switching unit 2022 can include a main power switch K1, a pre-charge resistor Rs1, and an AC pre-charge switch Ks1. The circuit formed by Rs1 and Ks1 in series is connected in parallel with K1, and the two ends of the parallel circuit are respectively connected to the grid input of the B-phase line and the EMC filter circuit of the B-phase line. The third switch can be K1 in Figure 3, the second resistor can be Rs1 in Figure 3, and the fourth switch can be Ks1 in Figure 3. It should be noted that when the second switching unit is turned on, in order to reduce the voltage difference across the main power switch K1 when it is energized, Ks1 needs to be closed first, and then K1 needs to be closed.

[0042] In this way, the capacitor in the first filter circuit of the C-phase line is charged through the third switch, the second resistor, and the fourth switch in the second switching unit, avoiding the risk of sticking caused by large voltage difference, simplifying operation, reducing cost, and helping to eliminate the reactive power consumption of the control circuit in standby mode, thereby improving the durability and safety of the control circuit.

[0043] In one possible embodiment, when the first switching unit is off, the second switching unit is off, and the third switching unit is on, the first live wire of the power module in the control circuit is connected to the first input terminal of the first filter module, the first output terminal of the first filter module is connected to the first input terminal of the rectifier module, the first output terminal of the rectifier module is connected to the first terminal of the first capacitor unit, the second output terminal of the rectifier module is connected to the second terminal of the first capacitor unit, the third output terminal of the rectifier module is connected to the first terminal of the second capacitor unit, the first terminal of the third switching unit is connected to the third live wire, the second terminal of the third switching unit is connected to the first terminal of the first diode unit, the second terminal of the first diode unit is connected to the first terminal of the first capacitor unit, the first terminal of the second diode unit is connected to the second terminal of the third switching unit, the second terminal of the second diode unit is connected to the first terminal of the second capacitor unit, the second terminal of the first capacitor unit is connected to the second terminal of the second capacitor unit, and the first terminal of the first diode unit and the second terminal of the second diode unit have the same polarity.

[0044] When the power module is powered on, the first switch unit is turned off, the second switch unit is turned off, and the third switch unit is turned on.

[0045] In this circuit, opening the first switch unit can disconnect the first and second switches, opening the second switch unit can disconnect the third and fourth switches, and closing the third switch can close the fifth switch. As shown in Figure 3, when the AC input is powered on, K1, K2, Ks1, and Ks2 are opened, and Ks is closed. At this time, the input AC power passes through the main power circuit of phase A and the pre-charging current of phase C, forming the uncontrolled rectified current of the line voltage, which pre-charges the bus capacitor for soft start. Please refer to Figure 4, which is a schematic diagram of the composition of an uncontrolled rectified pre-charging circuit of line voltage provided in an embodiment of this application. As shown in Figure 4, the line voltage uncontrolled rectifier pre-charge circuit may include the first inductor L2, the first fast recovery diode D1, the second fast recovery diode D2 in the three-phase Vienna circuit, the upper bus capacitor Cbus1 and the lower bus capacitor Cbus2 in the bus filter circuit 105, and the pre-charge soft-start resistor Rs, the pre-charge soft-start switch Ks, the first pre-charge soft-start rectifier diode D11, and the second pre-charge soft-start rectifier diode D12 in the pre-charge soft-start circuit 108. The first terminal voltage identifier of Cbus1 is Vbus+, and the first terminal voltage identifier of Cbus2 is Vbus-. When the power module is powered on, the input AC current can pass through phase A, L2, and then through D1 to charge Cbus1 and Cbus2. The input AC current can also pass through phase C, Rs and Ks, and then through D11 to charge Cbus1 and Cbus2. It should be noted that since the input AC current is a sinusoidal wave, when Vbus+ reaches the peak value of the input AC current, it indicates that the bus filter pre-charge is complete. After the bus filter pre-charging is completed, D1, D2, D11, and D12 are in the off state, making the reactive power loss in the line voltage uncontrolled rectifier pre-charging circuit almost zero.

[0046] As can be seen, in this example, by disconnecting the first and second switching units and turning on the third switching unit, the pre-charge soft-start function of the bus capacitor is realized when the input is powered on. This helps to eliminate the reactive power of the control circuit in the standby state and improves the durability and safety of the control circuit.

[0047] In one possible embodiment, the first switch unit is off, the second switch unit is off, and the third switch unit is on. Then, under a first condition, the first switch unit, the second switch unit, and the third switch unit are controlled to be on, whereby the first condition indicates that the first capacitor unit and the second capacitor unit have completed charging.

[0048] When the first switch unit is open, the second switch unit is open, and the third switch unit is turned on, the power module can receive a power-on command, indicating that the power module needs to enter the main power transmission working state. At this time, it is necessary to control the first switch unit, the second switch unit, and the third switch unit to turn on.

[0049] The first switching unit can close the first and second switches when it is turned on, and the second switching unit can close the third and fourth switches when it is turned on. As shown in Figure 3, when the first, second, and third switching units are turned on, i.e., K1, K2, Ks1, Ks2, and Ks are closed, the input current can charge Cx1 and Cx4 through phase A. The input current can also flow to GND through the circuit of R1 and R2 in series through phase A. The voltage Vasamp of R2 can be converted into a current Ia_samp. This current Ia_samp passes through L2 and then through D1 (when S1 is open), providing DC current at Vbus+. Similarly, the input current can also flow through phase B through R3 and R4 in series. The circuit flows to GND. The voltage Vbsamp of R4 can be converted into a current Ib_samp. This current Ib_samp passes through L3 and then through D3 (with S2 open), providing DC current at Vbus+. The input current can also flow to GND through the circuit of C phase, through R5 and R6 connected in series. The voltage Vcsamp of R6 can be converted into a current Ic_samp. This current Ic_samp passes through L4 and then through D5 (with S3 open), providing DC current at Vbus+. The above process is the main power transfer working state of the energy module.

[0050] Specifically, the first condition is expressed as follows:

[0051] V bus ≥1.414V in -ΔV

[0052] Among them, V bus V represents the difference between the first voltage detection value at the first terminal of the first capacitor unit and the second voltage detection value at the second terminal of the second capacitor unit. in ΔV represents the voltage difference between the first live wire and the third live wire, and ΔV represents the voltage difference across the third resistor when the power module is powered on.

[0053] As shown in Figure 3, when Ks is closed, the input current can flow through phase C, through Rs and D11, and then to Vbus+. Vbus+ is the voltage identifier of the first terminal of Cbus1, and Vbus- is the voltage identifier of the first terminal of Cbus2. The total voltage of the bus filter circuit is the total voltage of Cbus1 and Cbus2, that is, the difference between Vbus+ and Vbus-.

[0054] Where Vin is the voltage difference between the first and third live wires, which can represent the input line voltage; 1.414V in It can represent the peak value of the input line voltage; ΔV can represent the voltage difference across Rs; in the current path formed by Rs, Ks, and D11, 1.414Vin -ΔV can represent the total voltage of the bus filter circuit when the input voltage is at its maximum; V bus This represents the total voltage of the bus filter circuit as detected in real time. When the total voltage of the bus filter circuit monitored in real time is greater than or equal to the total voltage of the bus filter circuit when the input voltage is at its maximum, it indicates that Cbus and Cbus2 in the bus filter circuit have completed charging.

[0055] In this way, by comparing the total voltage of the bus filter circuit monitored in real time with the total voltage of the bus filter when the input voltage is at its maximum, it can be determined whether the first capacitor unit and the second capacitor unit in the second filter module have completed charging. This helps to ensure the safety of the pre-charge soft-start function of the bus capacitor when the input is powered on, helps to eliminate the reactive power of the control circuit in the standby state, and improves the durability and safety of the control circuit.

[0056] Specifically, under the first condition, the first switch unit, the second switch unit, and the third switch unit are controlled to be turned on, wherein the second switch and the fourth switch are closed; after a preset time period, the first switch and the third switch are closed.

[0057] In this circuit, the first switch unit can be turned on by first closing the second switch to precharge some of the capacitors in the first filter circuit. After a period of time, the capacitors in the first filter circuit will be fully charged, and then the first switch can be closed. As shown in Figure 3, the first switch unit can be turned on by first closing Ks2 to precharge Cx1, Cx2, Cx4, and Cx5. After a period of time, Cx1, Cx2, Cx4, and Cx5 will be fully charged, and then K2 can be closed.

[0058] In this circuit, the second switch unit can be turned on by first closing the fourth switch to precharge some of the capacitors in the first filter circuit. After a period of time, the capacitors in the first filter circuit will be fully charged, and then the third switch will be closed. As shown in Figure 3, the second switch unit can be turned on by first closing Ks1 to precharge Cx1, Cx3, Cx4, and Cx6. After a period of time, Cx1, Cx3, Cx4, and Cx6 will be fully charged, and then K1 will be closed.

[0059] As can be seen in this example, by connecting the pre-charge group and pre-charge switch in parallel with the main power relay switch, and closing the pre-charge switch before closing the main power relay switch, the risk of sticking due to excessive voltage difference when the main power relay switch is closed can be prevented. It should be noted that to effectively reduce the small voltage difference when the main power relay switch is closed, the resistance value of the pre-charge resistor can be set to a larger value.

[0060] In one possible embodiment, the first switch unit is turned off, the second switch unit is turned off, and the third switch unit is turned on. Then, it is determined whether the first voltage is greater than the first threshold. If the first voltage is greater than the first threshold, the first switch unit is turned off, the second switch unit is turned off, and the third switch unit is turned off.

[0061] Wherein, the first voltage is the voltage difference between the first live wire and the third live wire, and the first threshold is the peak value of the first voltage. If the first voltage is greater than the first threshold, it indicates that the input is overvoltage. It is necessary to first control the first and second switching units to disconnect, that is, disconnect K1, K2, Ks1 and Ks2, and then control the third switching unit to disconnect, that is, disconnect Ks. At this time, the power module enters the input overvoltage disconnection state.

[0062] In this case, the first switch unit can be disconnected by first disconnecting the second switch and then disconnecting the first switch, as shown in Figure 3. Ks2 can be disconnected first and then K2 can be disconnected. Similarly, the second switch unit can be disconnected by first disconnecting the fourth switch and then disconnecting the third switch, as shown in Figure 3. Ks1 can be disconnected first and then K1 can be disconnected.

[0063] As can be seen in this example, after the power module is powered on, it can determine whether there is an input overload by judging the input line voltage. When the input voltage is sampled as an input overvoltage, the third switching unit is disconnected to prevent the power module from injecting high voltage into the control circuit when there is an input overvoltage. This solves the risk of damage to internal components caused by input overvoltage and improves the durability and safety of the control circuit.

[0064] In one possible embodiment, the first switching unit is turned off, the second switching unit is turned off, and when the third switching unit is turned off, it is determined whether the first voltage is zero; if the first voltage is zero, the third switching unit is controlled to turn off.

[0065] When the power module receives a shutdown command, it indicates that the power module needs to stop the main power output and control the first and second switching units to be turned on. Specifically, the first and third switches can be turned off first, and then the second and fourth switches can be turned off, as shown in Figure 3. K1 and K2 can be turned off first, and then Ks1 and Ks2 can be turned off.

[0066] In this circuit, after the first and second switching units are disconnected, it is determined whether the first voltage is zero. If the first voltage is zero, it means that the input is in a power-off state. At this time, the third switching unit can be controlled to disconnect, that is, Ks is disconnected. If the first voltage is not zero, it means that the input is not powered off. At this time, the control circuit can enter the standby state. At this time, the third switching unit is turned on, and the control circuit forms the line voltage uncontrolled rectifier pre-charging circuit as shown in Figure 4.

[0067] As can be seen, in this example, when the power module receives a power-off command, it controls the first and second switch units to disconnect, and when it determines that the input is in a power-off state, it controls the third switch unit to disconnect. This allows the control circuit to combine the input voltage and the power module's command to control the switching units to turn on and off, simplifying operation, reducing costs, and improving the durability and safety of the control circuit.

[0068] This application also provides a three-phase power supply control method, applied to the three-phase power supply control circuit in any of the above embodiments. The control method includes: when the power module is powered on, controlling the third switching unit to be turned on, and the first switching unit and the second switching unit to be turned off; when the power module receives a power-on command, under a first condition, controlling the first switching unit, the second switching unit, and the third switching unit to be turned on, the first condition indicating that the first capacitor unit and the second capacitor unit have completed charging; or when the power module receives a power-off command, controlling the first switching unit and the second switching unit to be turned off, determining whether the first voltage is zero, and if the first voltage is zero, controlling the third switching unit to be turned off.

[0069] Please refer to Figure 5, which is a flowchart of a three-phase power supply control method provided in this application embodiment. The three-phase power supply control method is applicable to the three-phase power supply control circuit shown. In conjunction with Figure 3, as shown in Figure 5, the three-phase power supply control method includes the following steps: (1) Powering on the power module, specifically, the three-phase input of the power module is powered on; (2) The default state of the switching devices of the reactive power switching circuit and the pre-charge soft start circuit: K1, K2, Ks1, and Ks2 are in the open state, and Ks is in the closed state. Specifically, the input power is connected to the line voltage uncontrolled rectifier pre-charge circuit through L2, D1, D2, Cbus1, Cbus2, D11, D12, Ks, and Rs to realize the pre-charge soft start function of the bus capacitor when the input is powered on; (3) Real-time monitoring of the bus (3) Voltage Vbus and input line voltage Vac. Specifically, the line voltage can be obtained by the real-time difference between the phase voltage samples; (4) The power module is in standby mode. Specifically, the power module enters standby mode to wait for the power-on command; (5) Whether to enter the power-on process. Specifically, the power module receives the power-on command and enters the power-on process. Otherwise, the power module continues to wait, that is, the power module is in standby mode; (6) Vbus≥1.414Vac-△V. Specifically, it is determined whether the total voltage of the filter bus circuit is not less than the total voltage of the filter bus circuit when the input line voltage is at its maximum. When the total voltage Vbus of the filter bus circuit is greater than or equal to 1.When 414Vac-△V, it indicates that the filter bus circuit has completed the power-on pre-charge soft start and entered the power-on process. Otherwise, the power supply continues to wait for the pre-charge to be completed, that is, the power module is in standby mode; (7) Activate AC pre-charge switches Ks1 and Ks2; (8) Delay ts. Specifically, the capacitors in the EMC filter circuit charge faster, and the time can be set in nanoseconds (nm). It can also be set according to the resistance of the pre-charge group and the volume of the pre-charge capacitor. The delay can ensure that the safety capacitors in the EMC filter circuit are pre-charged, thereby ensuring that the voltage difference control is small when the main power relay switch is activated; (9) Activate the main power relay switches K1 and K2; (10) The power module enters the main power transmission working state; (11) Whether to enter the shutdown process. Specifically, the power module receives the shutdown command and enters the shutdown process. Otherwise, it still maintains the main power transmission working state, that is, the power module enters the main power transmission state; (12) Stop power output. , disconnect the main power relay switches K1 and K2, disconnect the AC precharge switches Ks1 and Ks2. Specifically, the power module enters the shutdown process, and K1, K2, Ks1, and Ks2 are all disconnected; (13) Whether the input is powered off, specifically, can be determined by detecting whether the input line voltage is zero. When the input line voltage is not zero, the power module enters the standby state, that is, returns to the standby state of the power module; (14) Real-time detection of input line voltage. When the input line voltage Vac > Vmax, the power module shuts down, disconnects the main power relay switches K1 and K2, disconnects the AC precharge switches Ks1 and Ks2, and disconnects the precharge soft start switch Ks. Specifically, Vmax is the threshold of the line voltage, which can be 1.414Vac. When the input line voltage is greater than the threshold of the line voltage, it indicates that the input is overvoltage. Disconnect the precharge soft start switch Ks, and the power module enters the input overvoltage release state; (15) The power module is powered off, and the strategy ends.

[0070] As can be seen, in this example, reactive power in standby mode is eliminated through the reactive power switching circuit and the pre-charge soft-start circuit, while also enabling the pre-charge soft-start function of the bus capacitor upon power-up. Furthermore, the zero-reactive-power control method, combined with input voltage detection at the port (i.e., the input line voltage and the total voltage of the bus filter circuit), eliminates the risk of sticking when the main power relay switch engages under large voltage differentials and also enables overvoltage disconnection in case of input overvoltage. This simplifies operation, reduces costs, and improves the durability and safety of the control circuit.

[0071] It should be noted that the three-phase voltage selected in this circuit scheme has no phase sequence requirement. Specifically, phases B and C can be selected to connect to the reactive power switching circuit, or phases A and B can be selected to connect to the reactive power switching circuit, or phases A and C can be selected to connect to the reactive power switching circuit. In addition, any two phases connected to the reactive power switching circuit can be selected to connect to the pre-charge soft starter circuit. Specifically, when phases B and C are connected to the reactive power switching circuit, either phase B or phase C can be selected to connect to the pre-charge soft starter circuit; when phases A and B are connected to the reactive power switching circuit, either phase A or phase B can be selected to connect to the pre-charge soft starter circuit; when phases A and C are connected to the reactive power switching circuit, either phase A or phase C can be selected to connect to the pre-charge soft starter circuit.

[0072] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0073] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. 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 application. Therefore, the content of this specification should not be construed as a limitation of this application.

[0074] While this application discloses the above information, it is not limited thereto. Any person skilled in the art can easily conceive of variations or substitutions without departing from the spirit and scope of this application, and can make various alterations and modifications, including combinations of the different functions and implementation steps described above, as well as software and hardware implementation methods, all of which are within the protection scope of this application.

Claims

1. A three-phase power control circuit, characterized by, The utility model relates to a power module, reactive switching module, first filter module, rectifier module, second filter module and soft start module, the reactive switching module includes first switch unit and second switch unit, the second filter module includes first capacitor unit and second capacitor unit, the soft start module includes third switch unit, first diode unit and second diode unit; The first live wire of the power module is connected with the first input end of the first filter module, the second live wire of the power module is connected with the first end of the first switch unit, the second end of the first switch unit is connected with the second input end of the first filter module, the third live wire of the power module is connected with the first end of the second switch unit, the second end of the second switch unit is connected with the third input end of the first filter module, the output end of the first filter module is connected with the input end of the rectifier module one by one, the first output end of the rectifier module is connected with the first end of the first capacitor unit, the second output end of the rectifier module is connected with the second end of the first capacitor unit, the third output end of the rectifier module is connected with the first end of the second capacitor unit, the first end of the third switch unit is connected with the third live wire, the second end of the third switch unit is connected with the first end of the first diode unit, the second end of the first diode unit is connected with the first end of the first capacitor unit, the first end of the second diode unit is connected with the second end of the third switch unit, the second end of the second diode unit is connected with the first end of the second capacitor unit, the second end of the first capacitor unit is connected with the second end of the second capacitor unit, the first end of the first diode unit is connected with the second end of the second diode unit, and the second end of the first capacitor unit is connected with the ground. The third switch unit includes a fifth switch and a third resistor, the first end of the third resistor is connected with the third live wire, the second end of the third resistor is connected with the first end of the fifth switch, the second end of the fifth switch is connected with the first end of the first diode unit, when the third switch unit is turned on, the fifth switch is closed.

2. The control circuit of claim 1, wherein, The first switch unit includes a first switch, a first resistor and a second switch, the first end of the first switch is connected with the first end of the first resistor, the second end of the first switch is connected with the first end of the second switch, the second end of the second switch is connected with the second end of the first resistor, the second live wire of the power module is connected with the second end of the second switch, and the second end of the first switch is connected with the second input end of the first filter module.

3. The control circuit of claim 1, wherein, ​ 4. The control circuit of claim 3, wherein, The second switch unit comprises a third switch, a second resistor and a fourth switch, a first end of the third switch is connected with a first end of the second resistor, a second end of the third switch is connected with a first end of the fourth switch, a second end of the fourth switch is connected with a second end of the second resistor, a third live wire of the power module is connected with the second end of the fourth switch, and the second end of the third switch is connected with a third input end of the first filter module.

5. The control circuit of claim 4, wherein, When the first switch unit is off, the second switch unit is off, and the third switch unit is on, the first live wire of the power module is connected with the first input end of the first filter module in the control circuit, the first output end of the first filter module is connected with the first input end of the rectifier module, the first output end of the rectifier module is connected with the first end of the first capacitor unit, the second output end of the rectifier module is connected with the second end of the first capacitor unit, the third output end of the rectifier module is connected with the first end of the second capacitor unit, the first end of the third switch unit is connected with the third live wire, the second end of the third switch unit is connected with the first end of the first diode unit, the second end of the first diode unit is connected with the first end of the first capacitor unit, the first end of the second diode unit is connected with the second end of the third switch unit, the second end of the second diode unit is connected with the first end of the second capacitor unit, the second end of the first capacitor unit is connected with the second end of the second capacitor unit, and the first end of the first diode unit is connected with the second end of the second diode unit in polarity.

6. The control circuit of claim 5, wherein, After the first switch unit is off, the second switch unit is off, and the third switch unit is on, Under a first condition, the first switch unit, the second switch unit and the third switch unit are controlled to be on, and the first condition indicates that the first capacitor unit and the second capacitor unit complete charging.

7. The control circuit of claim 6, wherein, Under the first condition, the first switch unit, the second switch unit and the third switch unit are controlled to be on, wherein, the second switch and the fourth switch are closed; after a preset time period, the first switch and the third switch are closed.

8. The control circuit of claim 7, wherein, The first condition is expressed as follows: V bus ≥ 1.414V in - ΔV wherein V bus represents a difference between a first voltage detection value of a first end of the first capacitor unit and a second voltage detection value of a second end of the second capacitor unit, V in represents a voltage difference between the first hot wire and the third hot wire, and ΔV represents a voltage difference across the third resistance when the power module is powered on.

9. The control circuit of claim 6, wherein, After the first switch unit is off, the second switch unit is off, and the third switch unit is on, it is determined whether a first voltage is greater than a first threshold value, the first voltage is a voltage difference between the first live wire and the third live wire, and the first threshold value is a peak value of the first voltage; if the first voltage is greater than the first threshold value, the first switch unit is off, the second switch unit is off, and the third switch unit is off.

10. The control circuit of claim 9, wherein, When the first switch unit is off, the second switch unit is off, and the third switch unit is off, it is determined whether the first voltage is zero; if the first voltage is zero, the third switch unit is controlled to be off.

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