Vienna rectifier, power equipment and charging pile

Abstract

The utility model discloses a Vienna rectifier, power equipment and a charging pile. The Vienna rectifier comprises a filter circuit, a full-bridge circuit and a slow start circuit, the input end of the filter circuit is used for being connected with an alternating current source, and the output end of the filter circuit is connected with the midpoint of a three-phase bridge arm of the full-bridge circuit; the slow start circuit is connected in series between the output end of the full-bridge circuit and the output end of the Vienna rectifier; the slow start circuit comprises a resistor and a switch, and the resistor and the switch are connected in parallel. The output end of the full-bridge circuit is connected with the slow start circuit, that is, the direct current side is connected with the slow start circuit, and relays and resistors for slow start do not need to be connected to three phases of alternating current, so that the number of hardware devices can be reduced, the cost is reduced, the number of the relays is reduced, and the control difficulty is also reduced. The slow start circuit can reduce very high surge current generated in the starting process of the Vienna rectifier, and the safety of devices in the full-bridge circuit is protected.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of power electronics, in particular to a Vienna rectifier, a power device and a charging pile. BACKGROUND

[0002] The Vienna rectifier is a commonly used three-phase three-level power factor correction (PFC) circuit, which can adopt a small filter inductance for filtering under the requirement of determining the current ripple, so that the volume of the circuit can be reduced, and the Vienna rectifier is widely applied in high-power occasions.

[0003] The input end of the Vienna rectifier is connected to three-phase alternating current, and a slow start circuit is arranged to avoid current impact when power is turned on. The sensor slow start circuit of the Vienna rectifier is arranged at the alternating current input end, and a slow start circuit is arranged for each phase, which causes a large number of devices and complex hardware, and the heat generated by the devices reduces the conversion efficiency of the Vienna rectifier. CONTENT OF THE UTILITY MODEL

[0004] Therefore, the application provides a Vienna rectifier, a power device and a charging pile, which can reduce the complexity of the slow start circuit and improve the conversion efficiency of the Vienna rectifier.

[0005] The application provides a Vienna rectifier, which comprises a filter circuit, a full-bridge circuit and a slow start circuit; the input end of the filter circuit is used for connecting an alternating current source, and the output end of the filter circuit is connected to the three-phase bridge arm midpoint of the full-bridge circuit; the slow start circuit is connected in series between the output end of the full-bridge circuit and the output end of the Vienna rectifier; the slow start circuit comprises a resistor and a switch, and the resistor and the switch are connected in parallel.

[0006] In a possible implementation manner, the slow start circuit is connected in series between the positive output end of the full-bridge circuit and the positive output end of the Vienna rectifier, or the slow start circuit is connected in series between the negative output end of the full-bridge circuit and the negative output end of the Vienna rectifier.

[0007] In a possible implementation manner, the application further comprises an auxiliary power supply and a controller; the output end of the Vienna rectifier is connected to a direct current bus; the auxiliary power supply is connected to the direct current bus, and electricity is taken from the direct current bus to supply power to the controller; the output end of the controller is connected to the switch, and is used for controlling the attraction and disconnection of the switch.

[0008] In a possible implementation, the first bus capacitor and the second bus capacitor are further included; the DC bus includes a DC positive bus and a DC negative bus; a first end of the first bus capacitor is connected to the DC positive bus, a second end of the first bus capacitor is connected to a DC bus midpoint, a first end of the second bus capacitor is connected to the DC bus midpoint, and a second end of the second bus capacitor is connected to the DC negative bus; and the soft-start circuit is connected between the positive output end of the full-bridge circuit and the first end of the first bus capacitor.

[0009] In a possible implementation, the full-bridge circuit is one of a three-phase uncontrolled rectifier circuit, a three-phase controlled rectifier circuit, a three-phase passive clamp circuit, or a three-phase active clamp circuit; when the full-bridge circuit is the three-phase uncontrolled rectifier circuit, the Vienna rectifier further includes a clamp circuit; and the clamp circuit is connected between a bridge-arm midpoint of the full-bridge circuit and a DC bus midpoint.

[0010] In a possible implementation, the filter circuit is a three-phase filter circuit, and each phase of the three-phase filter circuit includes a first inductor, a second inductor, and a filter capacitor; a first end of the first inductor is configured to be connected to a corresponding phase of the AC source; a second end of the first inductor is connected to the ground through the filter capacitor; a first end of the second inductor is connected to the second end of the first inductor; and a second end of the second inductor is connected to a bridge-arm midpoint of a corresponding phase of the full-bridge circuit.

[0011] In a possible implementation, the clamp circuit is a three-phase clamp circuit, and each phase of the three-phase clamp circuit includes a switching circuit; a first end of each phase of the switching circuit is connected to a bridge-arm midpoint of a corresponding phase of the three-phase uncontrolled rectifier circuit; and a second end of each phase of the switching circuit is connected to the DC bus midpoint.

[0012] In a possible implementation, each phase of the switching circuit includes one switch tube, or each phase of the switching circuit includes two switch tubes connected in series, and the two switch tubes connected in series form a bidirectional switch.

[0013] The application further provides a power device including the Vienna rectifier.

[0014] The application further provides a charging pile including the power device.

[0015] The Vienna rectifier provided by the application has the following advantages: a soft-start circuit is connected to the output end of the full-bridge circuit, that is, a soft-start circuit is connected to the DC side, and therefore it is not necessary to connect a relay and a resistor for soft-start to each of the three phases of the AC, which reduces the number of hardware devices and the cost, reduces the number of relays, and reduces the difficulty of control. The soft-start circuit can reduce a very high inrush current generated by the Vienna rectifier during the starting process, and protects the safety of devices in the full-bridge circuit. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A schematic diagram of a Vienna rectifier is provided for an embodiment of the present application.

[0017] Figure 2 A schematic diagram of another Vienna rectifier is provided for an embodiment of the present application.

[0018] Figure 3 A schematic diagram of still another Vienna rectifier is provided for an embodiment of the present application.

[0019] Figure 4 A schematic diagram of still another Vienna rectifier is provided for an embodiment of the present application.

[0020] Figure 5 A schematic diagram of still another Vienna rectifier is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to make the above objectives, characteristics and advantages of the present application more apparent and comprehensible, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] The Vienna rectifier provided by the embodiments of the present application can work in any scenario requiring three-phase rectification, and the present application does not limit the specific application scenario. For example, the Vienna rectifier can be applied to a base station, an inverter, an uninterruptible power supply or a charging pile, etc.

[0023] For the convenience of understanding, the Vienna rectifier is taken as an example in the charging pile scenario below. Generally, a charging pile includes a Vienna rectifier and a direct current / direct current (DC / DC) circuit. The input end of the Vienna rectifier is used to connect three-phase alternating current, and the output end of the Vienna rectifier is connected to the input end of the DC / DC circuit. The Vienna rectifier is used to adjust the input voltage of the DC / DC circuit, i.e., the direct current bus voltage, to meet the voltage regulation range requirement of the DC / DC circuit.

[0024] In the conventional technology, the soft-start circuit of the Vienna rectifier is connected to the alternating current input end. Each phase of the three-phase alternating current input end needs to be connected to a relay, and the two ends of at least two relays need to be connected in parallel with a resistor, i.e., three relays and at least two resistors need to be set. There are many hardware devices, and the control is complex.

[0025] The Vienna rectifier provided by the embodiments of the present application only needs to set a soft-start circuit at the direct current output end. Thus, only one relay and one resistor need to be set. There is no three-phase on the direct current side. Therefore, the number of hardware devices can be reduced, and the control is simple and easy to implement.

[0026] Referring to Figure 1 , the figure is a schematic diagram of a Vienna rectifier provided by an embodiment of the present application.

[0027] The Vienna rectifier provided by the embodiment of the application comprises a filter circuit 200, a full-bridge circuit and a soft-start circuit 100.

[0028] An input end of the filter circuit 200 is used for connecting an AC source, and an output end of the filter circuit 200 is connected to a three-phase bridge arm midpoint of the full-bridge circuit.

[0029] The soft-start circuit 100 is connected in series between an output end of the full-bridge circuit and an output end of the Vienna rectifier; specifically, the soft-start circuit can be connected in series between a positive output end of the full-bridge circuit and a positive output end of the Vienna rectifier. In another implementation, the soft-start circuit can also be connected in series between a negative output end of the full-bridge circuit and a negative output end of the Vienna rectifier. Figure 1 The full-bridge circuit is taken as an example in which the soft-start circuit 100 is connected in series between an output end of the full-bridge circuit and a positive output end of the Vienna rectifier.

[0030] The soft-start circuit 100 comprises a resistor R1 and a switch K1, and the resistor R1 and the switch K1 are connected in parallel. The application does not specifically limit the type of the switch K1, which can be a relay, for example.

[0031] The full-bridge circuit in the Vienna rectifier provided by the embodiment of the application can be any one of a three-phase uncontrolled rectification circuit, a three-phase fully-controlled rectification circuit, a three-phase passive clamping circuit or a three-phase active clamping circuit. Figure 1 The full-bridge circuit is taken as an example in which the full-bridge circuit is a three-phase uncontrolled rectification circuit. The three-phase uncontrolled rectification circuit comprises three bridge arms, a first bridge arm comprises a first diode D1 and a fourth diode D4 connected in series, a second bridge arm comprises a second diode D1 and a fifth diode D5 connected in series, and a third bridge arm comprises a third diode D3 and a sixth diode D6 connected in series.

[0032] When the full-bridge circuit is a three-phase uncontrolled rectification circuit, the Vienna rectifier further comprises a clamping circuit 300; the clamping circuit 300 is connected between a bridge arm midpoint of the three-phase uncontrolled rectification circuit and a DC bus midpoint.

[0033] The Vienna rectifier provided by the embodiment further comprises a first bus capacitor C4 and a second bus capacitor C5; the DC bus comprises a DC positive bus B+ and a DC negative bus B-.

[0034] A first end of the first bus capacitor C4 is connected to the DC positive bus B+, a second end of the first bus capacitor C4 is connected to the DC bus midpoint O, a first end of the second bus capacitor C5 is connected to the DC bus midpoint O, and a second end of the second bus capacitor C5 is connected to the DC negative bus B-.

[0035] The soft-start circuit 100 is connected between the positive output end of the full-bridge circuit and the first end of the first bus capacitor C4.

[0036] The working principle of the soft-start circuit 100 is as follows: When AC power initially supplies power to the Vienna rectifier, K1 is first disconnected, and resistor R1 suppresses the inrush current, protecting the components in the Vienna rectifier. Once the DC bus voltage rises to a certain level, K1 is energized, bypassing resistor R1. Resistor R1 in the diagram can be multiple resistors or a single resistor; there is no specific limitation. The DC bus voltage refers to the voltage between the positive DC bus B+ and the negative DC bus B-.

[0037] The Vienna rectifier provided in this application embodiment connects a soft-start circuit to the output terminal of the full-bridge circuit, that is, a soft-start circuit is connected to the DC side. This eliminates the need to connect relays and resistors for soft-start on all three phases of the AC circuit. This reduces the number of hardware components, lowers costs, and reduces the number of relays, thus simplifying control. The soft-start circuit can reduce the high inrush current generated during the startup process of the Vienna rectifier, protecting the safety of the components in the full-bridge circuit.

[0038] The following describes, with reference to the accompanying drawings, one implementation of the clamping circuit in the Vienna rectifier provided in this application.

[0039] See Figure 2 The figure is a schematic diagram of another Vienna rectifier provided in an embodiment of this application.

[0040] The filter circuit in the Vienna rectifier provided in this embodiment is a three-phase filter circuit. Each phase of the three-phase filter circuit includes a first inductor, a second inductor, and a filter capacitor; that is, the first inductors of the three phases are L1, L3, and L5, the second inductors of the three phases are L2, L4, and L6, and the filter capacitors of the three phases are C1, C2, and C3.

[0041] The first terminal of the first inductor is used to connect to the corresponding phase in the AC source. The second terminal of the first inductor is grounded through a filter capacitor. The first terminal of the second inductor is connected to the second terminal of the first inductor, and the second terminal of the second inductor is connected to the midpoint of the bridge arm of the corresponding phase in the full-bridge circuit.

[0042] The clamping circuit provided in this embodiment is a three-phase clamping circuit. Each phase clamping circuit includes a switching circuit. The first end of each phase switching circuit is connected to the midpoint of the corresponding phase arm of the full-bridge circuit, and the second end of each phase switching circuit is connected to the midpoint of the DC bus. Figure 2 Taking a switching circuit with one switching transistor per phase as an example, phase A includes a second switching transistor K2, phase B includes a third switching transistor K3, and phase C includes a fourth switching transistor K4. K2 is connected between the second terminal of L2 and the midpoint O of the DC bus. K3 is connected between the second terminal of L4 and the midpoint O of the DC bus. K4 is connected between the second terminal of L6 and the midpoint O of the DC bus.

[0043] Clamping circuits can, in addition to providing...Figure 2 The switch of each phase can be a switch tube, and the switch tube of each phase can be a bidirectional switch.

[0044] Referring to Figure 3 The figure is a schematic diagram of another Vienna rectifier provided by the embodiment of the application.

[0045] The Vienna rectifier provided by the embodiment further comprises an auxiliary power supply 10 and a controller 20.

[0046] The output end of the Vienna rectifier is connected to a DC bus, the auxiliary power supply 10 is connected to the DC bus, and the controller 20 is powered by electricity taken from the DC bus; the output end of the controller 20 is connected to the switch, and used for controlling the closing and opening of the switch K1.

[0047] Figure 3 The auxiliary power supply 10 shown in the figure is connected to a DC positive bus B+, and electricity is taken from the DC positive bus B+, and specifically, can further comprise a voltage dividing circuit connected to the DC positive bus B+, and used for dividing the voltage of the DC bus and providing the divided voltage to the auxiliary power supply 10, and the auxiliary power supply 10 provides power to the controller 20 after voltage stabilization and voltage reduction, and the embodiment does not specifically limit the implementation mode of the controller 20, for example, can be a single-chip microcomputer, a microprocessor or a digital processor.

[0048] In actual work, three-phase alternating current is powered on, the switch K1 is opened, and the DC bus is first soft-started through the resistor R1, the value of R1 can be determined according to the capacitance C of the DC bus capacitor, the expected voltage of the capacitor and the expected pre-charging time t, and R=t / 4C is calculated according to the formula; the bus is soft-started to a preset voltage U1, electricity is taken through the voltage dividing resistor, the auxiliary power supply is powered after electricity is taken, the auxiliary power supply starts to work normally, can provide power to the controller, and the controller can operate normally, at this time, the voltage across the switch K1 is the voltage difference across the resistor R1, the voltage difference meets the set value ΔU of the closing of the switch K1, after the switch K1 is closed, the resistor R1 is short-circuited by the switch K1, and the soft start is successful.

[0049] The Vienna rectifier provided by the embodiment of the application can automatically realize the starting stage of the soft start, because the soft start circuit is arranged on the DC side, and the auxiliary power supply takes electricity from the DC side, therefore, the auxiliary power supply cannot provide power to the controller temporarily at this time, and the controller also cannot control the closing of the switch K1, so that the current for charging the DC bus can only pass through the resistor R1, thereby the impact of the current can be inhibited. After being charged to a certain voltage, the auxiliary power supply starts to provide power to the controller, the controller controls the closing of the switch K1, and the resistor R1 is bypassed.

[0050] The full-bridge circuit in the Vienna rectifier described in the above embodiments is an example of a three-phase uncontrolled rectifier circuit. The following describes the implementation of the full-bridge circuit as a three-phase fully controlled rectifier circuit with reference to the accompanying drawings.

[0051] See Figure 4 This figure is a schematic diagram of another Vienna rectifier provided in an embodiment of this application.

[0052] When the full-bridge circuit is a three-phase fully controlled rectifier circuit, a clamping circuit is not required, i.e., no clamping circuit is needed. Figure 3 K2, K3, and K4 are shown.

[0053] The three-phase fully controlled rectifier circuit includes three bridge arms, each of which includes two controllable switches connected in series. The A-phase bridge arm includes the first controllable switch Q1 and the fourth controllable switch Q4 connected in series, the B-phase bridge arm includes the second controllable switch Q2 and the fifth controllable switch Q5 connected in series, and the C-phase bridge arm includes the third controllable switch Q3 and the sixth controllable switch Q6 connected in series.

[0054] The power consumption of the switching transistor in a three-phase fully controlled rectifier circuit is lower than that of a diode when it is turned on. Therefore, compared with a three-phase uncontrolled full-bridge circuit, the three-phase fully controlled rectifier circuit can reduce power consumption and improve the conversion efficiency of the Vienna rectifier.

[0055] The full-bridge circuit in the Vienna rectifier described in the above embodiments takes a three-phase uncontrolled rectifier circuit as an example. The following describes the implementation of the full-bridge circuit as a three-phase passive clamping circuit with reference to the accompanying drawings.

[0056] See Figure 5 This figure is a schematic diagram of another Vienna rectifier provided in an embodiment of this application.

[0057] When the full-bridge circuit is a three-phase passive clamping circuit, a clamping circuit is not required, i.e., no clamping circuit is needed. Figure 3 K2, K3, and K4 are shown.

[0058] The three-phase passive clamping circuit includes three bridge arms. Each bridge arm includes four controllable switches connected in series. The upper bridge arm of each bridge arm includes two controllable switches connected in series, and the lower bridge arm of each bridge arm includes two controllable switches connected in series. The upper half of the A-phase bridge arm includes the first controllable switch Q1 and the second controllable switch Q2 connected in series, and the lower half of the A-phase bridge arm includes the third controllable switch Q3 and the fourth controllable switch Q4. The upper half of the B-phase bridge arm includes the fifth controllable switch Q5 and the sixth controllable switch Q6 connected in series, and the lower half of the B-phase bridge arm includes the seventh controllable switch Q7 and the eighth controllable switch Q8. The upper half of the C-phase bridge arm includes the ninth controllable switch Q9 and the tenth controllable switch Q10 connected in series, and the lower half of the C-phase bridge arm includes the eleventh controllable switch Q11 and the twelfth controllable switch Q12.

[0059] The three-phase passive clamp circuit further comprises a clamp diode, as shown in Figure 5 The common point of the two clamp diodes is connected to the DC bus midpoint, that is, the midpoint voltage of the DC bus voltage, generally half of the DC bus voltage, is used to clamp the voltage of the three-phase bridge arm.

[0060] Based on the Vienna rectifier provided in the above embodiments, the embodiment of the present application further provides a power device, which comprises the Vienna rectifier introduced in the above embodiments.

[0061] The embodiment of the present application does not specifically limit the application scenarios of the power device, for example, it can be applied to any scenario in a photovoltaic system, an energy storage system, a photovoltaic energy storage system, an uninterruptible power supply or a charging pile, etc.

[0062] Due to various advantages of the Vienna rectifier, it is widely used in charging piles to convert the alternating current side into direct current for charging cars. That is, the present application further provides a charging pile, which comprises the power device introduced in the above embodiments.

[0063] Compared with the traditional three-phase buffer starting circuit, the Vienna rectifier provided in the present application uses fewer devices and has low cost, which can greatly improve the overall power density. At the same time, since the number of relays increases with the input current, the loss caused by the operation of the relays is also large. Therefore, the Vienna rectifier provided in the present application can improve the reliability and reduce the loss.

[0064] It should be noted that the embodiments in the present specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be referred to each other.

[0065] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A Vienna rectifier, characterized in that, include: Filtering circuit, full-bridge circuit, and soft-start circuit; The input terminal of the filter circuit is used to connect to an AC source, and the output terminal of the filter circuit is connected to the midpoint of the three-phase bridge arm of the full-bridge circuit. The soft-start circuit is connected in series between the output terminal of the full-bridge circuit and the output terminal of the Vienna rectifier; The soft-start circuit includes a resistor and a switch, wherein the resistor and the switch are connected in parallel.

2. The rectifier according to claim 1, characterized in that, The soft-start circuit is connected in series between the positive output terminal of the full-bridge circuit and the positive output terminal of the Vienna rectifier, or the soft-start circuit is connected in series between the negative output terminal of the full-bridge circuit and the negative output terminal of the Vienna rectifier.

3. The rectifier according to claim 1, characterized in that, Also includes: Auxiliary power supply and controller; The output terminal of the Vienna rectifier is connected to the DC bus. The auxiliary power supply is connected to the DC bus and draws power from the DC bus to supply power to the controller; The output of the controller is connected to the switch and is used to control the opening and closing of the switch.

4. The rectifier according to claim 3, characterized in that, Also includes: The first bus capacitor and the second bus capacitor; the DC bus includes a positive DC bus and a negative DC bus; The first end of the first bus capacitor is connected to the positive DC bus, the second end of the first bus capacitor is connected to the midpoint of the DC bus, the first end of the second bus capacitor is connected to the midpoint of the DC bus, and the second end of the second bus capacitor is connected to the negative DC bus. The soft-start circuit is connected between the positive output terminal of the full-bridge circuit and the first terminal of the first bus capacitor.

5. The rectifier according to any one of claims 1-4, characterized in that, The full-bridge circuit is one of the following: a three-phase uncontrolled rectifier circuit, a three-phase fully controlled rectifier circuit, a three-phase passive clamping circuit, or a three-phase active clamping circuit. When the full-bridge circuit is the three-phase uncontrolled rectifier circuit, the Vienna rectifier further includes: a clamping circuit; the clamping circuit is connected between the midpoint of the bridge arm of the full-bridge circuit and the midpoint of the DC bus.

6. The rectifier according to any one of claims 1-4, characterized in that, The filter circuit is a three-phase filter circuit, and each phase of the three-phase filter circuit includes a first inductor, a second inductor, and a filter capacitor. The first terminal of the first inductor is used to connect to the corresponding phase in the AC source; The second end of the first inductor is grounded through the filter capacitor, the first end of the second inductor is connected to the second end of the first inductor, and the second end of the second inductor is connected to the midpoint of the bridge arm of the corresponding phase of the full-bridge circuit.

7. The rectifier according to claim 5, characterized in that, The clamping circuit is a three-phase clamping circuit. Each phase clamping circuit includes a switching circuit. The first end of the switching circuit of each phase is connected to the midpoint of the bridge arm of the corresponding phase of the three-phase uncontrolled rectifier circuit, and the second end of the switching circuit of each phase is connected to the midpoint of the DC bus.

8. The rectifier according to claim 7, characterized in that, Each phase of the switching circuit includes one switching transistor, or each phase of the switching circuit includes two switching transistors connected in series, wherein the two switching transistors connected in series form a bidirectional switch.

9. A power device, characterized in that, Includes the Vienna rectifier as described in any one of claims 1-8.

10. A charging pile, characterized in that, Includes the power device as described in claim 9.

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