Vehicle-mounted charging system

Abstract

The utility model provides a vehicle-mounted charging system, comprising a first converter having an AC side and a DC side; the inverter is coupled between a power battery and a motor of the vehicle and comprises three bridge arms and a direct current capacitor bridged between a positive bus and a negative bus, and each bridge arm comprises an upper bridge arm switch coupled with the positive bus and a lower bridge arm switch coupled with the negative bus; an intermediate node of the upper bridge arm switch and the lower bridge arm switch of each bridge arm is coupled with one motor winding in the plurality of motor windings; the second converter comprises a conversion circuit on the first side, a conversion circuit on the second side and an isolation transformer; the on-off switches comprise a first on-off switch and a third on-off switch which are arranged on the positive bus and a second on-off switch and a fourth on-off switch which are arranged on the negative bus; and the controller is electrically connected with each on-off switch, the inverter and the second converter.

Description

Technical Field

[0001] This utility model relates to an on-board charging system. Background Technology

[0002] Hybrid electric vehicles (HEVs) and electric vehicles (EVs) are the two major types of new energy vehicles, both of which are equipped with on-board charging systems. These systems convert AC power from the power grid into DC power to charge the vehicle's battery (i.e., the on-board battery).

[0003] In existing technologies, on-board charging systems typically include a two-stage topology, which mainly consists of two conversion stages: AC-DC and DC-DC. A large-capacity bus capacitor is connected in parallel between the two stages. This is because the input of the AC-DC conversion stage receives AC current and AC voltage in the form of a sine wave, which results in the input signal having twice the power frequency ripple. Since the frequency of power frequency AC is relatively low (e.g., 50Hz), a large-capacity bus capacitor needs to be placed between the AC-DC conversion stage and the DC-DC conversion stage to eliminate the twice power frequency ripple.

[0004] However, these large-capacity bus capacitors have high capacitance values ​​and are relatively expensive, thus increasing manufacturing costs. Additionally, large-capacity bus capacitors are relatively bulky, increasing the space occupied by the vehicle system. In practical applications, to meet the high capacitance requirements, electrolytic capacitors are usually chosen as bus capacitors because, for the same volume, the capacitance value of electrolytic capacitors is generally greater than that of film capacitors. However, electrolytic capacitors have a relatively short lifespan. Utility Model Content

[0005] Against this backdrop, embodiments of the present invention propose an improved on-board charging system that utilizes the DC capacitor of the inverter to achieve reactive power compensation without the need for a large-capacity bus capacitor. The on-board charging system according to embodiments of the present invention reduces costs and extends the overall lifespan of the system, exhibiting both economic efficiency and reliability.

[0006] Therefore, according to one embodiment of the present invention, an on-board charging system is provided, comprising: a first converter having an AC side and a DC side, the AC side being configured to be coupled to an external AC power source outside the vehicle; an inverter coupled between the vehicle's power battery and a motor, including three bridge arms and a DC capacitor bridging the positive and negative buses, each bridge arm including an upper bridge arm switch coupled to the positive bus and a lower bridge arm switch coupled to the negative bus, and the upper bridge arm switch of each bridge arm being coupled to the intermediate node of the lower bridge arm switch and one of a plurality of motor windings; a second converter, including a first... The system includes a conversion circuit on one side, a conversion circuit on the second side, and an isolation transformer coupled between the conversion circuits on the first and second sides, wherein the conversion circuit on the second side is a full-bridge circuit including two switching arms; multiple on / off switches, including first and third on / off switches on the positive bus and second and fourth on / off switches on the negative bus, wherein the first and second on / off switches are located between the inverter and the power battery, and the third and fourth on / off switches are located between the power battery and the conversion circuit on the second side; and a controller electrically connected to each on / off switch, the inverter, and the second converter.

[0007] In one embodiment, each of the two switching arms includes a high-side switch coupled to the positive bus and a low-side switch coupled to the negative bus. The intermediate node of the high-low side switch of one of the two switching arms is connected to the intermediate node of the upper and lower bridge arm switches of one of the three bridge arms of the inverter. The intermediate node of the high-low side switch of the other of the two switching arms is connected to the neutral point of a plurality of motor windings.

[0008] In one embodiment, the first converter and the second converter constitute a busless capacitor-based two-stage converter.

[0009] In one embodiment, the conversion circuit on the second side, at least a portion of the plurality of motor windings, and the inverter constitute a dual active bridge circuit.

[0010] In one embodiment, the DC capacitor has a storage state and a discharge state. In the storage state, the DC capacitor stores the reactive portion of the energy transmitted by the dual active bridge circuit. In the discharge state, the energy stored in the DC capacitor is released through the dual active bridge circuit.

[0011] In one embodiment, the second converter includes an output capacitor connected across the positive and negative buses and located on a second side of the second converter.

[0012] In one embodiment, the on-board charging system includes an electromagnetic interference filter that is connected between the positive and negative buses and located on the AC side of the first converter.

[0013] In one embodiment, the controller outputs control signals to each on / off switch to control its on / off state, so that the multiple on / off switches are in a first combination state corresponding to the AC charging mode of the on-board charging system or a second combination state corresponding to the traction mode of the on-board charging system.

[0014] In one embodiment, the plurality of on / off switches have a first combination state corresponding to the AC charging mode of the on-board charging system and a second combination state corresponding to the traction mode of the on-board charging system.

[0015] In one embodiment, the first combined state includes: both the first and second on / off switches are off, and both the third and fourth on / off switches are on; the second combined state includes: both the first and second on / off switches are on, and both the third and fourth on / off switches are off. Attached Figure Description

[0016] The technical solution of this utility model will become clearer from the following detailed description taken in conjunction with the accompanying drawings. It is to be understood that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this utility model.

[0017] Figure 1 This is a schematic block diagram of an on-board charging system according to one embodiment of the present invention.

[0018] Figure 2 It shows Figure 1 An example circuit of an on-board charging system. Detailed Implementation

[0019] The specific implementation of this utility model will now be described with reference to the accompanying drawings.

[0020] Figure 1 An on-board charging system 100 (hereinafter referred to as "System 100") according to an embodiment of the present invention is shown. System 100 is installed on a vehicle V and has an AC charging mode and a traction mode. In AC charging mode, the vehicle is not moving, the inverter does not need to perform DC-AC conversion, and the power battery 110 of the vehicle V receives electrical power from an external AC power source 200. In traction mode, the vehicle is moving, the inverter performs DC-AC conversion to convert the DC power from the power battery 110 into AC power to supply the motor 120 for driving the vehicle.

[0021] The external AC power source 200 is, for example, an AC charging station coupled to an AC power grid. The external AC power source 200 can also be other types of AC power sources capable of charging the vehicle's power battery 110.

[0022] Figure 2An embodiment of an on-board charging system 100 is shown. For example... Figure 2 As shown, the system 100 mainly includes: a first converter 10, a second converter 20, an inverter 30, multiple on / off switches S1 to S4, and a controller 40.

[0023] The first converter 10 has an AC side and a DC side, wherein the AC side can be coupled to an external AC power source 200 outside the vehicle, and the DC side is coupled to a DC side (e.g., a first DC side) of the second converter 20. The first converter 10 can transfer electrical energy from its AC side to its DC side to transfer electrical power from the external AC power source to the second converter 20.

[0024] Inverter 30, also known as a traction inverter, is coupled between the vehicle's power battery 110 and motor 120. Inverter 30 converts the direct current (DC) from the power battery 110 into alternating current (AC) and supplies this AC power to the motor 120 to drive the vehicle. Figure 2 As shown, motor 120 is a three-phase motor and includes three phase windings: phase A winding 120A, phase B winding 120B, and phase C winding 120C. Inverter 30 includes three bridge arms: first bridge arm 30A, second bridge arm 30B, and third bridge arm 30C. Each bridge arm includes an upper bridge arm switch coupled to the positive bus and a lower bridge arm switch coupled to the negative bus. The intermediate node between the upper and lower bridge arm switches of each bridge arm is coupled to a corresponding phase winding of motor 120. For example, the intermediate node NA of the upper arm switch Q1 and the lower arm switch Q2 of the first arm 30A is coupled to the motor winding 120A; the intermediate node NB of the upper arm switch Q3 and the lower arm switch Q4 of the second arm 30B is coupled to the motor winding 120B; and the intermediate node NC of the upper arm switch Q5 and the lower arm switch Q6 of the third arm 30C is coupled to the motor winding 120C.

[0025] Each of the switches Q1 through Q6 can be implemented as a controllable power semiconductor switching device. In one embodiment, each switch can be implemented as a metal-oxide-semiconductor field-effect transistor (MOSFET). This transistor includes a parasitic diode with freewheeling capability. In another embodiment, each switch can be implemented as including an insulated-gate bipolar transistor (IGBT) and a diode, wherein the cathode of the diode is connected to the collector of the transistor, and the anode is connected to the emitter of the transistor. The IGBT is a controllable switching device. The diode is an uncontrollable switching device and can provide freewheeling functionality.

[0026] Inverter 30 also includes a DC capacitor (DC capacitor) C TThis is used to store the reactive component (e.g., second harmonic ripple component) in the energy output of the second converter 20 or to release its stored energy to compensate for reactive power in the output of the second converter 20. For example... Figure 2 As shown, DC capacitor C T It is connected between the positive and negative busbars. Specifically, the DC capacitor C T One terminal of the inverter 30 is connected to the upper bridge arm switch of each bridge arm and the positive bus, and that switch terminal is connected, and the DC capacitor C T The other terminal is connected to the lower bridge arm switch of each bridge arm of inverter 30 and to the negative bus. This DC capacitor has a storage state (storing energy) and a discharge state (releasing energy). These two states will be discussed in detail below in conjunction with reactive power compensation.

[0027] The second converter 20 includes a first-side conversion circuit 21, a second-side conversion circuit 22, and an isolation transformer 23. The second converter 20 is a DC / DC converter. The second converter 20 can transfer electrical power from the first side to the second side to transfer electrical power from the external AC power source 200, via the first converter 10, to the power battery 110 for charging the power battery 110. The first-side conversion circuit 21 is a DC / AC conversion circuit, and the second-side conversion circuit 22 is an AC / DC conversion circuit. The isolation transformer 23 has a first-side winding 23A and a second-side winding 23B. The first-side winding 23A is coupled to the first-side conversion circuit 21, and the second-side winding 23B is coupled to the second-side conversion circuit 22.

[0028] The first-side conversion circuit 21 can be implemented using a full-bridge circuit composed of several power switching devices. The second-side conversion circuit 22 can also be implemented using a full-bridge circuit composed of several power switching devices. An embodiment of the second-side conversion circuit 22 will be described below.

[0029] like Figure 2 As shown, the second converter 20 is implemented as a full-bridge circuit consisting of four switches 221 to 224. Switches 221 and 222 constitute the first switching arm, with switch 221 being a high-side switch connected to the positive bus and switch 222 being a low-side switch connected to the negative bus. The intermediate node 220A between the high-side switch 221 and the low-side switch 222 is connected to the neutral point of the motor phase winding. Switches 223 and 224 constitute the second switching arm, with switch 223 being a high-side switch connected to the positive bus and switch 224 being a low-side switch connected to the negative bus. The intermediate node 220B between the high-side switch 223 and the low-side switch 224 is connected to the intermediate node of the upper and lower arm switches of one of the three bridge arms of the inverter 30, for example, the intermediate node NB of the upper and lower arm switches of the second bridge arm 30B.

[0030] It should be understood that the embodiments of this utility model do not limit the connection of the intermediate node 220B of switches 223 and 224 to the intermediate node of the upper or lower bridge arm switches of the inverter. Although in Figure 2 The example shows the connection of the intermediate node NB of the upper and lower bridge arm switches of the second bridge arm 30B. According to an embodiment of the present invention, the intermediate node 220B of switches 223 and 224 can also be connected to the intermediate node of the upper and lower bridge arm switches of the first or third bridge arm of the inverter 30.

[0031] The second converter 20 also includes an output capacitor Co. The output capacitor Co is connected across the positive and negative buses and coupled to the output side of the second converter 20 (e.g., the second side), serving to stabilize the output voltage and filter the signal.

[0032] According to the embodiments of this utility model, there is no need to set a bus capacitor between the first converter 10 and the second converter 20. Therefore, the first converter 10 and the second converter 20 constitute a bus capacitor-free two-stage converter.

[0033] Each of the multiple on / off switches S1-S4 is an electronic switch with two states: ON and OFF. Each on / off switch is in the ON or OFF state under the control of the controller 40. Each on / off switch can be, for example, a relay.

[0034] See below Figure 2 This section describes the connection methods for each on / off switch.

[0035] The first on / off switch S1 is located on the positive bus and between the power battery 110 and the inverter 30. Specifically, one switch terminal of the first on / off switch S1 is connected to the positive terminal of the power battery 110, and the other switch terminal is connected to the switch terminal of the upper bridge arm switch Q1 of the first bridge arm 30A of the inverter 30 that is connected to the positive bus.

[0036] The second on / off switch S2 is located on the negative bus and between the power battery 110 and the inverter 30. Specifically, one terminal of the second on / off switch S2 is connected to the negative terminal of the power battery 110, and the other terminal is connected to the terminal of the lower bridge arm switch Q2 of the first bridge arm 30A of the inverter 30 that is connected to the negative bus.

[0037] The third on / off switch S3 is located on the positive busbar and between the power battery 110 and the second-side conversion circuit 23 of the second converter 20. Specifically, one switch terminal of the third on / off switch S3 is connected to the positive terminal of the power battery 110, and the other switch terminal is connected to the switch terminal of the high-side switch 223 of the second switch arm of the second-side conversion circuit 23 that is connected to the positive busbar.

[0038] The fourth on / off switch S4 is located on the negative bus and between the power battery 110 and the second-side conversion circuit 23 of the second converter 20. Specifically, one switch terminal of the fourth on / off switch S4 is connected to the negative terminal of the power battery 110, and the other switch terminal is connected to the switch terminal of the lower-side switch 224 of the second switch arm of the second-side conversion circuit 23 that is connected to the negative bus.

[0039] The controller 40 is electrically connected to multiple on / off switches S1-S4, the first converter 10, the second converter 20, and the inverter 30, respectively. For example, the controller 40 is connected to the multiple on / off switches S1-S4, the first converter 10, the second converter 20, and the inverter 30 via wires. The controller 40 can output controller signals to each on / off switch, each switch of the first and second converters, and each switch of the inverter, thereby controlling the on / off state of these switches.

[0040] In one embodiment, the controller 40 outputs control signals to the first to fourth on / off switches respectively, causing the first and second on / off switches to be turned off, while the third and fourth on / off switches are turned on, thereby enabling the system 100 to operate in AC charging mode. In this mode, the power battery 110 is charged by the external AC power supply 200.

[0041] In another embodiment, the controller 40 outputs control signals to the first to fourth on / off switches, respectively, so that the first and second on / off switches are turned on (ON), while the third and fourth on / off switches are turned off (OFF), thereby enabling the system 100 to operate in traction mode. In this case, the power battery 110 serves as the power source for vehicle movement.

[0042] According to an embodiment of this utility model, the second-side conversion circuit 22, at least a portion of the plurality of motor windings 120A to 120C, and the inverter 30 constitute a dual active bridge circuit. In AC charging mode, the DC capacitor of the inverter 30 can be in a storage state or a discharge state. For example, when the instantaneous power output from the second converter 20 is greater than the current required charging power of the power battery 100 (which can be issued by the battery management system BMS of the power battery), the DC capacitor is in a storage state to store the reactive portion of the energy output from the second converter 20 transmitted through the dual active bridge circuit. When the instantaneous power output from the second converter 20 is less than the current required charging power of the power battery 100, the DC capacitor is in a discharge state to release its stored energy through the dual active bridge circuit.

[0043] Additionally, according to embodiments of the present invention, system 100 may further include an electromagnetic interference filter (EMI filter) 50. The EMI filter 50 is connected across the positive and negative buses and coupled to the input side of the first converter 10 to eliminate or reduce electromagnetic interference from an external AC power supply 200 (e.g., the power grid), thereby improving the performance of system 100 and ensuring that system 100 complies with relevant electromagnetic compatibility (EMC) standards.

[0044] While some embodiments have been described above, these embodiments are given by way of example only and are not intended to limit the scope of the present invention. The appended claims and their equivalents are intended to cover all modifications, substitutions, and alterations made within the scope and spirit of the present invention.

Claims

1. An on-board charging system, characterized by, The vehicle charging system comprises: a first converter having an AC side and a DC side, the AC side configured to be able to couple with an external AC power source outside the vehicle; an inverter coupled between a power battery of the vehicle and a motor, comprising three bridge arms and a DC capacitor connected across a positive bus and a negative bus, each bridge arm comprising an upper bridge arm switch coupled with the positive bus and a lower bridge arm switch coupled with the negative bus, and a middle node between the upper bridge arm switch and the lower bridge arm switch of each bridge arm being coupled with one of a plurality of motor windings; a second converter comprising a first side conversion circuit, a second side conversion circuit, and an isolation transformer coupled between the first side conversion circuit and the second side conversion circuit, wherein the second side conversion circuit is a full-bridge circuit comprising two switch arms; a plurality of on-off switches comprising first and third on-off switches disposed on the positive bus and second and fourth on-off switches disposed on the negative bus, wherein the first and second on-off switches are both located between the inverter and the power battery, and the third and fourth on-off switches are both located between the power battery and the second side conversion circuit; and a controller electrically connected with each of the on-off switches, the inverter, and the second converter.

2. The in-vehicle charging system according to claim 1, characterized by, each of the two switch arms comprises a high-side switch coupled with the positive bus and a low-side switch coupled with the negative bus, a middle node between the high-side switch and the low-side switch of one of the two switch arms is connected with a middle node between the upper bridge arm switch and the lower bridge arm switch of one of the three bridge arms of the inverter, a middle node between the high-side switch and the low-side switch of the other of the two switch arms is connected with a neutral point of the plurality of motor windings.

3. The in-vehicle charging system according to claim 1, wherein The first converter and the second converter constitute a busless capacitor two-stage converter.

4. The in-vehicle charging system of claim 1, wherein, The second side conversion circuit, at least part of the plurality of motor windings, and the inverter constitute a dual active bridge circuit.

5. The in-vehicle charging system according to claim 4, wherein The DC capacitor has a storage state and a discharge state, in the storage state, the DC capacitor stores a reactive part of energy transmitted by the dual active bridge circuit, in the discharge state, the energy stored in the DC capacitor is released through the dual active bridge circuit.

6. The in-vehicle charging system of claim 1, wherein, The second converter comprises an output capacitor connected across the positive bus and the negative bus and located at the second side of the second converter.

7. The in-vehicle charging system of claim 1, wherein, The vehicle charging system comprises an electromagnetic interference filter connected across the positive bus and the negative bus and located at the AC side of the first converter.

8. The in-vehicle charging system of claim 1, wherein, The controller outputs control signals to each of the on-off switches for controlling the on-off state thereof, so that the plurality of on-off switches are in a first combined state corresponding to an AC charging mode of the vehicle charging system or a second combined state corresponding to a traction mode of the vehicle charging system.

9. The in-vehicle charging system of claim 1, wherein, The plurality of on-off switches have a first combined state corresponding to an AC charging mode of the vehicle charging system and a second combined state corresponding to a traction mode of the vehicle charging system.

10. The in-vehicle charging system according to claim 8 or 9, characterized by, The first combined state comprises that the first and second on-off switches are both off, and the third and fourth on-off switches are both on; The second combined state comprises that the first and second on-off switches are both on, and the third and fourth on-off switches are both off.

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