Capacitor charging and discharging control circuit and alternating current rectifier

Abstract

The invention discloses a capacitor charge and discharge control circuit and an alternating current rectifier, and relates to the technical field of charge and discharge control, the circuit comprises a rectification module, a charge and discharge common module and a bus capacitor which are connected in sequence, and a control module connected with the rectification module; the charging and discharging common module comprises a resistor and a switch unit, the first end of the resistor and the first end of the switch unit are connected together and then connected to the rectifier module, the second end of the resistor and the second end of the switch unit are connected together and then connected to the bus capacitor, and the control end of the switch unit is connected with the control module; the control module controls the switch unit to be switched off when the alternating current rectifier is in a pre-charging mode or a discharging mode, so that the resistor is matched with the rectifier module and the bus capacitor to form a pre-charging loop or a discharging loop, and charging buffering or discharging is conducted on the bus capacitor. And when the alternating current rectifier completes pre-charging, the switch unit is controlled to be switched on so as to bypass the resistor. The circuit is simple in structure and low in cost, reduces the area of a circuit board, and improves the power density of the circuit.

Description

Technical Field

[0001] The present application relates to the technical field of charge and discharge control, and in particular to a capacitor charge and discharge control circuit and an AC rectifier. Background Art

[0002] AC rectifier is a device that converts AC power into DC power. On the rectifier side of the AC rectifier, a busbar large capacitor is placed for filtering. Generally, a corresponding pre-charging circuit needs to be designed to slow down the charging rate of the large capacitor.

[0003] In the related art, two relays and one resistor are set on each phase of the AC side of the AC rectifier to form a pre-charging circuit. The problem is that the large current generated at the moment of closing or the instantaneous large current caused by the short circuit of the main circuit may cause the surface of the relay contact to melt and ablate, forming adhesion. In addition, at least two relays and one resistor are required for each phase, the circuit structure is complex, and the components forming the circuit occupy a certain space, which limits the design requirements of high power density, and the design cost is also high. Summary of the invention

[0004] The main purpose of the present application is to provide a capacitor charging and discharging control circuit and an AC rectifier, aiming to solve the technical problems in the related art that the pre-charging circuit of the AC rectifier has the risk of relay adhesion, complex circuit structure, large space occupation and high cost.

[0005] To achieve the above-mentioned purpose, the present application proposes a capacitor charge and discharge control circuit, which is applied to an AC rectifier. The capacitor charge and discharge control circuit includes a rectifier module, a charge and discharge common module and a bus capacitor connected in sequence, and also includes a control module connected to the rectifier module and used to control the working state of the rectifier module;

[0006] The charge-discharge common module includes a resistor and a switch unit, a first end of the resistor is connected to the first end of the switch unit and then connected to the rectifier module, a second end of the resistor is connected to the second end of the switch unit and then connected to the bus capacitor, and a control end of the switch unit is connected to the control module;

[0007] The control module is also used to: control the switch unit to be disconnected when the AC rectifier is in a pre-charging mode or a discharging mode, so that the resistor is connected between the rectifier module and the bus capacitor, and cooperate with the rectifier module and the bus capacitor to form a pre-charging circuit or a discharging circuit to charge and buffer or discharge the bus capacitor; control the switch unit to be turned on when the AC rectifier completes pre-charging and enters a normal working mode, so as to bypass the resistor.

[0008] In one embodiment, the switch unit includes a first switch device and a second switch device connected in series, each of the first switch device and the second switch device includes a body diode, and the first body diode of the first switch device is connected to the top of the second body diode of the second switch device.

[0009] In one embodiment, the control module is specifically used to: when starting the machine, control the first switch device and the second switch device to turn off, so that the resistor is connected to the pre-charging circuit, so as to use the uncontrolled rectification of the rectifier module to pre-charge the bus capacitor; and at the end of pre-charging, control the first switch device and the second switch device to turn on, and control the rectifier module to enter a normal working state.

[0010] In one embodiment, the control module is specifically used to: when shutting down, control the first switch device and the second switch device to turn off, and control the upper and lower bridge arm switches of any phase in the rectifier module to turn on, so that the rectifier module, the resistor and the bus capacitor form a discharge loop to discharge the bus capacitor.

[0011] In one embodiment, the first end of the resistor and the first end of the first switching device are respectively connected to the positive output end of the rectifier module, the second end of the resistor and the first end of the second switching device are respectively connected to the first end of the bus capacitor, and serve as the bus positive output end U1+; or, the first end of the resistor and the first end of the first switching device are respectively connected to the negative output end of the rectifier module, the second end of the resistor and the first end of the second switching device are respectively connected to the second end of the bus capacitor, and serve as the bus negative output end U1-.

[0012] In one embodiment, the capacitor charge and discharge control circuit also includes a filter module and an inductor, the input end of the filter module is connected to the AC power supply, the positive output end of the filter module is connected to the positive input end of the rectifier module through an inductor, and the negative output end of the filter module is connected to the negative input end of the rectifier module.

[0013] In one embodiment, the input end of the rectifier module is connected to a three-phase four-wire AC power source;

[0014] The rectifier module includes four-phase bridge arms, each phase bridge arm includes upper and lower bridge arm switches connected to each other, the first ends of the upper bridge arm switches in the four-phase bridge arms are connected, serving as the positive output end of the rectifier module, the common contact point of the second end of the upper bridge arm switch and the first end of the lower bridge arm switch in the four-phase bridge arm is respectively connected to the four wires of the three-phase four-wire AC power supply, and the second ends of the lower bridge arm switches in the four-phase bridge arms are connected, serving as the negative output end of the rectifier module.

[0015] In one embodiment, the input end of the rectifier module is connected to a single-phase two-wire AC power source;

[0016] The rectifier module includes a two-phase bridge arm, each phase bridge arm includes an upper bridge arm switch and a lower bridge arm switch connected to each other, the first ends of the upper bridge arm switches in the two-phase bridge arms are connected, and serve as the positive output end of the rectifier module, the common contact point of the second end of the upper bridge arm switch and the first end of the lower bridge arm switch in the two-phase bridge arm is respectively connected to the two wires of the single-phase two-wire AC power supply, and the second ends of the lower bridge arm switches in the two-phase bridge arms are connected, and serve as the negative output end of the rectifier module.

[0017] In one embodiment, the first switch device and the second switch device are both controllable switch tubes, and the controllable switch tube includes any one of a field effect tube, an insulated gate bipolar transistor or a power semiconductor switch.

[0018] In addition, to achieve the above-mentioned purpose, the present application also proposes an AC rectifier, including the capacitor charging and discharging control circuit as described above.

[0019] One or more technical solutions proposed in this application have at least the following technical effects:

[0020] A capacitor charge and discharge control circuit is proposed, comprising a rectifier module, a charge and discharge common module and a bus capacitor connected in sequence, and a control module connected to the rectifier module, wherein the charge and discharge common module comprises a resistor and a switch unit, wherein the first end of the resistor is connected to the first end of the switch unit and then connected to the rectifier module, the second end of the resistor is connected to the second end of the switch unit and then connected to the bus capacitor, and the control end of the switch unit is connected to the control module; the circuit can disconnect the switch unit when the AC rectifier is in a pre-charging mode, and connect the resistor alone between the rectifier module and the bus capacitor, so that the resistor cooperates with the rectifier module and the bus capacitor. The capacitor forms a pre-charging loop, and the bus capacitor is charged and buffered, which realizes the pre-charging of the bus capacitor and slows down the charging rate of the bus capacitor, and can avoid the generation of spike current when the bus capacitor is charged; the switch unit can also be disconnected when the AC rectifier is in the discharge mode, so that the resistor cooperates with the rectifier module and the bus capacitor to form a discharge loop to discharge the bus capacitor; it can also control the switch unit to conduct when the AC rectifier completes the pre-charging and enters the normal working mode, and bypass the resistor to form a complete rectifier circuit by using the switched-on switch unit to cooperate with the rectifier module and the bus capacitor to realize the normal operation of the AC rectifier. It can be seen that by using the charge and discharge common module of the circuit, both rectification pre-charging and active discharge can be realized. Compared with the pre-charging circuit with the risk of relay adhesion in the related technology, the circuit improves safety, stability and reliability; not only the circuit structure is simple and the cost is low, but also it will be beneficial to reduce the circuit board area and improve the power density of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0023] Figure 1 It is a schematic diagram of a pre-charging circuit of an AC rectifier in the related art;

[0024] Figure 2 This is a schematic diagram of the circuit principle of an embodiment of a capacitor charge and discharge control circuit of the present application;

[0025] Figure 3 A schematic diagram of the circuit principle of another embodiment of the capacitor charge and discharge control circuit of the present application;

[0026] Figure 4 A schematic diagram of a pre-charging circuit in another embodiment of the capacitor charging and discharging control circuit of the present application;

[0027] Figure 5 This is a schematic diagram of a discharge circuit in another embodiment of the capacitor charge and discharge control circuit of the present application.

[0028] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0030] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) in the embodiments of the present application, the directional indication is only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture. If the specific posture changes, the directional indication will also change accordingly. In addition, if there are descriptions of "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, scheme B, or schemes that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0031] The AC rectifier is an AC-DC rectifier that converts AC into DC. On the rectifier side of the AC rectifier, a busbar capacitor is placed for filtering. At the moment of equipment startup, the busbar capacitor will generate a large peak current when charged, so it is generally necessary to design a corresponding pre-charging circuit to slow down the charging rate of the large capacitor.

[0032] like Figure 1 The figure shows a schematic diagram of the pre-charging circuit of the AC rectifier in the related art. The pre-charging circuit is composed of relays K1~K6 and resistors R1~R3, and is set on the AC side of the AC rectifier. When the device is started, the relays K1, K3 and K5 are closed, and the AC current passes through the resistors R1, R2 and R3 to pre-charge the large capacitor C1; when the charging of the large capacitor C1 is completed, the relays K1, K3 and K5 are disconnected, and the relays K2, K4 and K6 are closed to enter the rectification stage.

[0033] The problem with this pre-charging circuit, which sets two relays and one resistor for each phase on the AC side of the AC rectifier, is that since the AC rectifier will inevitably have current shocks, short circuits or other electrical faults during operation, the relays of the pre-charging circuit will also be frequently disconnected or closed synchronously. In this process, the large current generated at the moment of closing or the instantaneous large current caused by the short circuit of the main circuit may cause the surface of the relay contacts to melt and burn, forming adhesion. In addition, at least two relays and one resistor are required for each phase, the circuit structure is complex, and the devices that form the circuit occupy a certain space, which limits the design requirements of high power density, and the design cost is also high.

[0034] In view of the above problems, the present application provides a capacitor charge and discharge control circuit and an AC rectifier. The present application and the following embodiments are described below in conjunction with the accompanying drawings.

[0035] The present application provides a capacitor charging and discharging control circuit, which is applied to an AC rectifier.

[0036] In one embodiment of the present application, refer to Figure 2 , Figure 2 This is a circuit principle diagram of an embodiment of a capacitor charge and discharge control circuit. The capacitor charge and discharge control circuit may include a rectifier module, a charge and discharge common module and a bus capacitor C1 connected in sequence. The capacitor charge and discharge control circuit may also include a control module connected to the rectifier module for controlling the working state of the rectifier module.

[0037] Among them, the charge and discharge sharing module includes a resistor R11 and a switch unit. The first end of the resistor R11 is connected to the first end of the switch unit and then connected to the rectifier module. The second end of the resistor R11 is connected to the second end of the switch unit and then connected to the bus capacitor C1. The control end of the switch unit is connected to the control module.

[0038] The control module is also used to: control the switch unit to be disconnected when the AC rectifier is in a pre-charging mode or a discharging mode, so that the resistor is connected between the rectifier module and the bus capacitor, and cooperate with the rectifier module and the bus capacitor to form a pre-charging circuit or a discharging circuit to charge and buffer or discharge the bus capacitor; control the switch unit to be turned on when the AC rectifier completes pre-charging and enters a normal working mode, so as to bypass the resistor.

[0039] It should be noted that the capacitor charge and discharge control circuit can be applied to AC rectifiers of AC power supplies or on-board chargers and other equipment. The rectifier module is a circuit that realizes the rectifier function, and the bus capacitor C1 is a large energy storage capacitor connected in parallel between the positive and negative output terminals of the rectifier module. The bus capacitor C1 can be a large capacitor inside the AC rectifier.

[0040] It should also be noted that the control module can be a microprocessor independently set in the circuit, or it can be an external control device, such as a host computer, a controller independent of the AC rectifier, etc., which is not specifically limited here. The control end of each switch device in the rectifier module is connected to the control module, receives the rectifier control signal, and realizes the rectifier work of the rectifier module. The control end of each switch device in the switch unit is also connected to the control module, and the control module controls the on and off of each switch device.

[0041] In a feasible implementation, the switch unit includes a first switch device and a second switch device connected in series, each of the first switch device and the second switch device includes a body diode, and the first body diode of the first switch device is connected top to top with the second body diode of the second switch device.

[0042] It should be noted that, in the switch unit, the first body diode of the first switch device and the second body diode of the second switch device are connected top to top, so that the first switch device and the second switch device are symmetrically connected, and the resistor R11 is connected in parallel with the symmetrically connected first switch device and the second switch device. Specifically, the first end of the resistor R11 and the first end of the first switch device are respectively connected to the rectifier module, the second end of the resistor R11 and the first end of the second switch device are respectively connected to the bus capacitor C1, the second end of the first switch device is connected to the second end of the second switch device, and the control end of the first switch device and the control end of the second switch device are respectively connected to the control module.

[0043] For example, Figure 2 As shown, the first switch device is a switch tube Q9, the second switch device is a switch tube Q10, the drain of Q9 is connected to the rectifier module, the source of Q9 is connected to the source of Q10, the drain of Q10 is connected to the bus capacitor C1, one end of the resistor R11 is connected to the drain of Q9, and the other end is connected to the drain of Q10, and the gate of Q9 and the gate of Q10 can be connected to the control module ( Figure 2 ), receives the control signal output by the control module to realize the on-off control of Q9 and Q10.

[0044] In a feasible implementation, the first end of the resistor R11 and the first end of the first switching device are respectively connected to the positive output end of the rectifier module, and the second end of the resistor R11 and the first end of the second switching device are respectively connected to the first end of the bus capacitor C1 and serve as the bus positive output end U1+.

[0045] It should be noted that the charge-discharge common module is connected between the rectifier module and the bus capacitor C1, and can be specifically connected to the positive electrode side of the bus after the rectifier module.

[0046] For example, Figure 2 As shown, the first end of the resistor R11 and the drain of Q9 are respectively connected to the positive output end of the rectifier module, the second end of the resistor R11 and the drain of Q10 are respectively connected to the first end of the bus capacitor C1 and serve as the bus positive output end U1+. At this time, the negative output end of the rectifier module is connected to the second end of C1 and serves as the bus negative output end U1-.

[0047] In a feasible implementation manner, the first switch device and the second switch device are both controllable switch tubes, and the controllable switch tube includes any one of a field effect tube, an insulated gate bipolar transistor or a power semiconductor switch.

[0048] Exemplarily, the first switching device and the second switching device can be field effect transistors, such as MOS tubes (Metal-Oxide-Semiconductor Field-Effect Transistor: Metal Oxide Semiconductor Field-Effect Transistor), JFET tubes (Junction Field-Effect Transistor: Junction Field Effect Transistor), etc.; insulated gate bipolar transistors (IGBT tubes: Insulated Gate Bipolar Transistor); or power semiconductor switches, such as gallium nitride power semiconductors, silicon carbide power devices, etc. Controllable switching tubes, can be selected according to needs in actual applications, and are not specifically limited here.

[0049] The capacitor charge and discharge control circuit provided in this embodiment includes a rectifier module, a charge and discharge common module and a bus capacitor connected in sequence, and a control module connected to the rectifier module, wherein the charge and discharge common module includes a resistor and a switch unit, a first end of the resistor is connected to the first end of the switch unit and then connected to the rectifier module, a second end of the resistor is connected to the second end of the switch unit and then connected to the bus capacitor, and a control end of the switch unit is connected to the control module; the circuit can disconnect the switch unit when the AC rectifier is in a pre-charging mode, and connect the resistor separately between the rectifier module and the bus capacitor, so that the resistor cooperates with the rectifier module and the bus The line capacitor forms a pre-charging loop, and the bus capacitor is charged and buffered, which realizes the pre-charging of the bus capacitor and slows down the charging rate of the bus capacitor, and can avoid the generation of spike current when the bus capacitor is charged; the switch unit can also be disconnected when the AC rectifier is in the discharge mode, so that the resistor cooperates with the rectifier module and the bus capacitor to form a discharge loop to discharge the bus capacitor; when the AC rectifier completes the pre-charging and enters the normal working mode, the switch unit can be controlled to be turned on, and the resistor can be bypassed, so as to use the turned-on switch unit to cooperate with the rectifier module and the bus capacitor to form a complete rectifier circuit to realize the normal operation of the AC rectifier. It can be seen that by using the charge and discharge common module of the circuit, both rectification pre-charging and active discharge can be realized. Compared with the pre-charging circuit with the risk of relay adhesion in the related technology, the circuit improves safety, stability and reliability; not only the circuit structure is simple and low cost, but also it will be beneficial to reduce the circuit board area and improve the power density of the circuit.

[0050] In another embodiment of the present application, refer to Figure 3 , Figure 3 This is a circuit principle diagram of another embodiment of a capacitor charge and discharge control circuit. The first end of the resistor R11 and the first end of the first switch device are respectively connected to the negative output end of the rectifier module, and the second end of the resistor R11 and the first end of the second switch device are respectively connected to the second end of the bus capacitor C1 and serve as the bus negative output end U1-.

[0051] It should be noted that the charge-discharge common module is connected between the rectifier module and the bus capacitor C1, and can be specifically connected to the negative electrode side of the bus after the rectifier module.

[0052] For example, Figure 3 As shown, the first end of the resistor R11 and the drain of Q9 are respectively connected to the negative output end of the rectifier module, the second end of the resistor R11 and the drain of Q10 are respectively connected to the second end of the bus capacitor C1 and serve as the bus negative output end U1-. At this time, the positive output end of the rectifier module is connected to the first end of C1 and serves as the bus positive output end U1+. In addition, the gate of Q9 and the gate of Q10 can be connected to the control module ( Figure 3 ), receives the control signal output by the control module to realize the on-off control of Q9 and Q10.

[0053] In a specific embodiment, the control module is specifically used to, when starting the machine, control the first switch device and the second switch device to turn off, so that the resistor is connected to the pre-charging circuit, so as to use the uncontrolled rectification of the rectifier module to pre-charge the bus capacitor; and at the end of pre-charging, control the first switch device and the second switch device to turn on, and control the rectifier module to enter a normal working state.

[0054] It should be noted that starting refers to the powering on of the device where the AC rectifier to which the circuit belongs is located. The pre-charging circuit includes an AC power supply, a rectifier module and a bus capacitor. When the resistor of the charge-discharge common module is connected to the pre-charging circuit, if the charge-discharge common module is at the positive pole of the bus, the complete pre-charging circuit is a circuit formed by the AC power supply, rectifier module, resistor and bus capacitor connected in sequence. If the charge-discharge common module is at the negative pole of the bus, the complete pre-charging circuit is a circuit formed by the AC power supply, rectifier module, bus capacitor and resistor connected in sequence.

[0055] For example, Figure 4 The schematic diagram of the pre-charging circuit in this embodiment is shown. Figure 3 In the capacitor charge and discharge control circuit shown, when starting, the control module can control Q9 and Q10 to turn off, so that the resistor R11 is connected to the pre-charging circuit, so as to use the uncontrolled rectification of the rectifier module to pre-charge the bus capacitor C1, specifically, the body diode of the upper bridge arm switch of the single-phase or three-phase bridge arm of the positive electrode in the rectifier module is used for uncontrolled rectification, and the rectified DC power output from the positive electrode of the rectifier module will be used to pre-charge C1; until the pre-charging is completed (for example, the voltage across C1 reaches a certain set value, the charging time reaches a set time, etc., which are not specifically limited here), the control module controls Q9 and Q10 to turn on, and prepares for the rectification start of the AC rectifier; then, the control module can control the bridge arm switches of each phase bridge arm in the rectifier module to control the rectifier module to enter a normal working state, so as to realize the normal rectification work of the AC rectifier.

[0056] In another specific embodiment, the control module is specifically used to, when shutting down, control the first switching device and the second switching device to turn off, and control the upper and lower bridge arm switches of any phase in the rectifier module to turn on, so that the rectifier module, the resistor and the bus capacitor form a discharge loop to discharge the bus capacitor; and at the end of the discharge, control the upper and lower bridge arm switches of any phase to turn off.

[0057] It should be noted that shutdown means that the equipment where the AC rectifier to which the circuit belongs is located is shut down and powered off. If the charge-discharge common module is at the positive pole of the bus, the complete discharge circuit is a circuit formed by the rectifier module, bus capacitor and resistor connected in sequence. If the charge-discharge common module is at the negative pole of the bus, the complete discharge circuit is a rectifier module, resistor and bus capacitor connected in sequence. The rectifier module can include a rectifier circuit with two-phase bridge arms or four-phase bridge arms, depending on whether the AC power supply of the input AC power is a single-phase or three-phase power supply. Regardless of the type of rectifier circuit the rectifier module is, the control module only needs to control the upper and lower bridge arm switches of any one of the phase bridge arms to be turned on.

[0058] For example, Figure 5 The schematic diagram of the discharge circuit in this embodiment is shown. Figure 3 In the capacitor charge and discharge control circuit shown, when shutting down, the control module can control Q9 and Q10 to turn off, and control the upper and lower bridge arm switches Q7 and Q8 of any phase in the rectifier module, such as the fourth phase, to turn on, so that Q7 and Q8 of the rectifier module, the bus capacitor C1 and the resistor R11 form a discharge circuit to discharge the bus capacitor C1; until the discharge is completed, that is, when the voltage of C1 is discharged to meet the requirements (for example, it drops below a set value, the discharge time reaches the set time, etc., which is not specifically limited here), the control module controls Q7 and Q8 to turn off again to prepare for the pre-charging of the next startup.

[0059] The capacitor charge and discharge control circuit provided in this embodiment proposes a circuit module shared by pre-charging and discharging. During startup and shutdown, the charge and discharge shared module is connected to a loop or a loop is formed using the charge and discharge shared module by controlling the on and off of the first switch device and the second switch device in the charge and discharge shared module, so that the resistance in the charge and discharge shared module is shared. While satisfying the current limiting effect required for pre-charging of the AC rectifier, the active discharge function of the AC rectifier can also be realized. The charge and discharge shared module has a high utilization rate, thereby improving the utilization rate of the circuit.

[0060] In another embodiment of the present application, refer to Figure 2 and Figure 3The capacitor charge and discharge control circuit may further include a filter module and an inductor, wherein the input end of the filter module is connected to the AC power supply, the positive output end of the filter module is connected to the positive input end of the rectifier module through an inductor, and the negative output end of the filter module is connected to the negative input end of the rectifier module.

[0061] It should be noted that the filter module is located after the AC power supply, filters the AC power provided by the AC power supply, and then provides the filtered AC power to the rectifier module, so the filter module can use an AC filter. The inductor is located between the filter module and the rectifier module, which can filter out the high-frequency noise and clutter signals of the filtered AC power, and can also filter out the harmonic current generated by the rectifier module during rectification, so as to improve the quality of the DC power output by the rectifier module, thereby improving the quality of the output of the entire circuit.

[0062] In a possible implementation, continue to refer to Figure 2 and Figure 3 The AC power supply can be a three-phase four-wire AC power supply, and the input end of the rectifier module is connected to the three-phase four-wire AC power supply.

[0063] The rectifier module may include a four-phase bridge arm, each phase bridge arm includes upper and lower bridge arm switches connected to each other, the first ends of the upper bridge arm switches in the four-phase bridge arms are connected, serving as the positive output end of the rectifier module, the common contact points of the second ends of the upper bridge arm switches and the first ends of the lower bridge arm switches in the four-phase bridge arms are respectively connected to the four wires of the three-phase four-wire AC power supply, and the second ends of the lower bridge arm switches in the four-phase bridge arms are connected, serving as the negative output end of the rectifier module.

[0064] For example, the number of inductors may be three, such as Figure 2 and Figure 3 As shown, it includes resistors L1, L2 and L3; the four-wire input end of the filter module is correspondingly connected to the four wires AC-L1, AC-L2, AC-L3 and AC-N of the three-phase four-wire AC power supply, and the three-phase positive output end of the filter module is respectively connected to the common connection point of the second end of the upper bridge arm switch and the first end of the lower bridge arm switch in the first phase, second phase and third phase bridge arm of the rectifier module through an inductor, as shown in FIG. Figure 2 and Figure 3As shown, one end of L1 is connected to the first phase positive output end of the filter module, the other end of L1 is connected to the common point of the second end of Q1 and the first end of Q2 in the first phase bridge arm of the rectifier module, one end of L2 is connected to the second phase positive output end of the filter module, the other end of L2 is connected to the common point of the second end of Q3 and the first end of Q4 in the second phase bridge arm of the rectifier module, one end of L3 is connected to the third phase positive output end of the filter module, and the other end of L3 is connected to the common point of the second end of Q5 and the first end of Q6 in the third phase bridge arm of the rectifier module; the negative output end of the filter module is connected to the common point of the second end of the upper bridge arm switch and the first end of the lower bridge arm switch in the fourth phase bridge arm of the rectifier module, as shown in FIG. Figure 2 and Figure 3 As shown, the negative output end of the filter module is connected to the common point of the second end of Q7 and the first end of Q8 in the fourth phase bridge arm of the rectifier module.

[0065] In another feasible implementation manner, the AC power source may be a single-phase two-wire AC power source, and the input end of the rectifier module is connected to the single-phase two-wire AC power source.

[0066] The rectifier module includes a two-phase bridge arm, each phase bridge arm includes an upper bridge arm switch and a lower bridge arm switch connected to each other, the first ends of the upper bridge arm switches in the two-phase bridge arms are connected, and serve as the positive output end of the rectifier module, the common contact point of the second end of the upper bridge arm switch and the first end of the lower bridge arm switch in the two-phase bridge arm is respectively connected to the two wires of the single-phase two-wire AC power supply, and the second ends of the lower bridge arm switches in the two-phase bridge arms are connected, and serve as the negative output end of the rectifier module.

[0067] Exemplarily, the number of inductors can be one; the two-wire input end of the filter module is connected to the two wires of the single-phase two-wire AC power supply respectively, the positive output end of the filter module is connected to the common connection point of the second end of the upper bridge arm switch and the first end of the lower bridge arm switch in the first phase bridge arm of the rectifier module through the inductor, and the negative output end of the filter module is connected to the common connection point of the second end of the upper bridge arm switch and the first end of the lower bridge arm switch in the second phase bridge arm of the rectifier module.

[0068] The capacitor charge and discharge control circuit provided in this embodiment can be applied to AC power supplies including single-phase and three-phase, vehicle-mounted chargers and other equipment, so the circuit has high applicability and practicality.

[0069] The application also proposes an AC rectifier.

[0070] In one embodiment of the present application, the AC rectifier may include an AC power supply and a capacitor charging and discharging control circuit.

[0071] Among them, the AC power supply can be a single-phase two-wire AC power supply or a three-phase four-wire AC power supply, which is used to provide AC power as the input of the capacitor charge and discharge control circuit; the capacitor charge and discharge control circuit outputs DC power and provides it to subsequent components, which is not specifically limited here.

[0072] It should be noted that the specific structure of the capacitor charge and discharge control circuit refers to the above embodiments. Since the AC rectifier adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0073] The above are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect application in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A capacitor charge and discharge control circuit, applied to an AC rectifier, characterized in that: The capacitor charge and discharge control circuit includes a rectifier module, a charge and discharge common module and a bus capacitor connected in sequence, and also includes a control module connected to the rectifier module and used to control the working state of the rectifier module; The charge-discharge common module includes a resistor and a switch unit, a first end of the resistor and a first end of the switch unit are connected together and then connected to the rectifier module, a second end of the resistor and a second end of the switch unit are connected together and then connected to the bus capacitor, and a control end of the switch unit is connected to the control module; The control module is also used to: control the switch unit to be disconnected when the AC rectifier is in a pre-charging mode or a discharging mode, so that the resistor is connected between the rectifier module and the bus capacitor, and cooperate with the rectifier module and the bus capacitor to form a pre-charging circuit or a discharging circuit to charge, buffer or discharge the bus capacitor; and control the switch unit to be turned on when the AC rectifier completes pre-charging and enters a normal working mode, so as to bypass the resistor.

2. The capacitor charge and discharge control circuit according to claim 1, characterized in that: The switch unit includes a first switch device and a second switch device connected in series, the first switch device and the second switch device both include a body diode, and a first body diode of the first switch device is connected to a top of a second body diode of the second switch device.

3. The capacitor charge and discharge control circuit according to claim 2, characterized in that: The control module is specifically used for: When starting the machine, the first switch device and the second switch device are controlled to be turned off, so that the resistor is connected to the pre-charging circuit, so as to pre-charge the bus capacitor by utilizing the uncontrolled rectification of the rectifier module; and at the end of pre-charging, the first switch device and the second switch device are controlled to be turned on, and the rectifier module is controlled to enter a normal working state.

4. The capacitor charge and discharge control circuit according to claim 3, characterized in that: The control module is specifically used for: When shutting down, the first switch device and the second switch device are controlled to be turned off, and the upper and lower bridge arm switches of any phase in the rectifier module are controlled to be turned on, so that the rectifier module, the resistor and the bus capacitor form a discharge loop to discharge the bus capacitor.

5. The capacitor charge and discharge control circuit according to any one of claims 2 to 4, characterized in that: The first end of the resistor and the first end of the first switch device are respectively connected to the positive output end of the rectifier module, and the second end of the resistor and the first end of the second switch device are respectively connected to the first end of the bus capacitor and serve as the bus positive output end U1+; or, The first end of the resistor and the first end of the first switch device are respectively connected to the negative output end of the rectifier module, and the second end of the resistor and the first end of the second switch device are respectively connected to the second end of the bus capacitor and serve as the bus negative output end U1-.

6. The capacitor charge and discharge control circuit according to claim 5, characterized in that: The capacitor charge and discharge control circuit also includes a filter module and an inductor. The input end of the filter module is connected to an AC power supply, the positive output end of the filter module is connected to the positive input end of the rectifier module through the inductor, and the negative output end of the filter module is connected to the negative input end of the rectifier module.

7. The capacitor charge and discharge control circuit according to claim 5, characterized in that: The input end of the rectifier module is connected to a three-phase four-wire AC power supply; The rectifier module includes four-phase bridge arms, each phase bridge arm includes upper and lower bridge arm switches connected to each other, the first ends of the upper bridge arm switches in the four-phase bridge arms are connected, serving as the positive output end of the rectifier module, the common contact points of the second ends of the upper bridge arm switches and the first ends of the lower bridge arm switches in the four-phase bridge arms are respectively connected to the four wires of the three-phase four-wire AC power supply, and the second ends of the lower bridge arm switches in the four-phase bridge arms are connected, serving as the negative output end of the rectifier module.

8. The capacitor charge and discharge control circuit according to claim 5, characterized in that: The input end of the rectifier module is connected to a single-phase two-wire AC power supply; The rectifier module includes two-phase bridge arms, each phase bridge arm includes upper and lower bridge arm switches connected to each other, the first ends of the upper bridge arm switches in the two-phase bridge arms are connected, serving as the positive output end of the rectifier module, the common contact point of the second end of the upper bridge arm switch and the first end of the lower bridge arm switch in the two-phase bridge arms are respectively connected to the two wires of the single-phase two-wire AC power supply, and the second ends of the lower bridge arm switches in the two-phase bridge arms are connected, serving as the negative output end of the rectifier module.

9. The capacitor charge and discharge control circuit according to any one of claims 2 to 4, characterized in that: The first switch device and the second switch device are both controllable switch tubes, and the controllable switch tube includes any one of a field effect tube, an insulated gate bipolar transistor or a power semiconductor switch.

10. An AC rectifier, characterized in that: The invention comprises a capacitor charge and discharge control circuit as claimed in any one of claims 1 to 9.

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