An electric drive system

Abstract

The utility model provides a kind of electric drive system, applied to electric drive technical field.In the utility model, it can specifically include inverter unit, and inverter unit can specifically include at least one group of series connection upper bridge arm and lower bridge arm, wherein upper bridge arm includes: gate drive circuit and switch tube connected with the output end of gate drive circuit, gate drive circuit includes parallelly connected active discharge resistance branch;Since the utility model has been connected with active discharge resistance branch in parallel on opening resistance branch, and has been set switch between opening resistance branch and drive control chip, to when drive control chip outputs a small duty cycle pulse signal, it is disconnected by switch, using the characteristics that switch tube is in unsaturated time work in linear region, through switch tube itself active discharge bus capacitor, without additional active discharge circuit, both reduce the occupied area of PCB board, and reduce circuit cost.

Description

Technical Field

[0001] This utility model relates to the field of circuit technology, and in particular to an electric drive system. Background Technology

[0002] The inverter for electric vehicles, also known as the electric vehicle drive motor controller, connects its DC input to the high voltage of the power battery, requiring a large-capacity support capacitor to stabilize the bus voltage. When the vehicle stops operating and the inverter is de-energized, the bus support capacitor still retains high voltage and residual energy. Passive or active discharge measures are needed to release this residual energy. Active discharge technology can quickly reduce the bus capacitor voltage to a safe range, preventing high-voltage safety faults. A backup power supply is a redundant design intended to improve the reliability of the motor controller. When the battery or DC-DC converter fails to supply power to the inverter's low-voltage system, the backup power supply switches in, allowing the motor controller to continue operating.

[0003] There are three common active discharge methods. The first is to control the switching on and off of the IGBT bridge arms to allow current to flow through the motor windings, dissipating capacitor energy through resistive heating. This method requires high control precision and is prone to motor malfunction and vehicle vibration. The second method involves connecting a power resistor in series with a switch, then in parallel across the capacitor bus. By controlling the switch to adjust the duty cycle, the resistor operates within a certain power range, consuming the remaining capacitor energy. The disadvantage of this method is severe resistor heating, making heat dissipation difficult and resulting in low reliability. The third method uses a single-phase or multi-phase IGBT bridge arm pass-through, typically with the upper bridge pass-through and the lower bridge short-time switching. The energy of the bus capacitor is dissipated through the charging and discharging of the IGBT's parasitic capacitance. This method does not require additional hardware circuitry, but it subjects the lower IGBT to a large current, as well as excessive voltage and current changes, which can easily damage the IGBT wafer. Utility Model Content

[0004] The purpose of this invention is to provide an electric drive system that uses an inverter unit to actively discharge the bus capacitor, thereby reducing costs and not increasing the footprint of the PCB board.

[0005] To address the aforementioned technical problems, this utility model provides an electric drive system, comprising a high-voltage battery, a bridge inverter, and a motor connected in sequence, wherein the bridge inverter includes:

[0006] The bus capacitor is connected to the positive and negative DC bus between the high-voltage battery and the inverter unit;

[0007] The inverter unit is connected in parallel with the two ends of the bus capacitor and includes at least one set of upper and lower bridge arms connected in series. The upper bridge arm includes a gate drive circuit and a switching transistor connected to the output terminal of the gate drive circuit. The gate drive circuit includes an active discharge resistor branch connected in parallel, which is used to turn on the active discharge resistor branch and control the switching transistor to be in a linear state to enter the active discharge mode when an active discharge control signal is received.

[0008] Furthermore, the gate drive circuit also includes: an on-resistor branch connected in parallel with the active discharge resistor branch, used to turn on and control the switching transistor to be in a saturated state to enter normal operation mode when an on-control signal is received.

[0009] Furthermore, the active discharge resistor branch includes multiple active discharge resistors connected in parallel, the turn-on resistor branch includes multiple turn-on resistors connected in parallel, and the resistance value of the active discharge resistor is greater than the resistance value of the turn-on resistor.

[0010] Furthermore, the resistance value of the active discharge resistor is N times the resistance value of the turn-on resistor, and 5≤N≤10.

[0011] Furthermore, the gate drive circuit may further include: a drive control chip and a shut-off resistor branch; wherein, the drive control chip includes a first output terminal and a second output terminal, the first output terminal being connected to the input terminal of the active discharge resistor branch, for outputting a first pulse signal to the active discharge resistor branch when the active discharge control signal is received, and outputting a second pulse signal to the active discharge resistor branch when the turn-on control signal is received;

[0012] The input terminal of the shut-off resistor branch is connected to the second output terminal of the drive control chip, and the output terminal is connected to the gate of the switching transistor. It is used to control the switching transistor to be in the off state to enter the shut-off mode when a shut-off control signal is received.

[0013] Furthermore, the pulse width of the first pulse signal is smaller than the pulse width of the second pulse signal.

[0014] Furthermore, a switch is provided on the turn-on resistor branch to control the opening or closing of the turn-on resistor branch.

[0015] Furthermore, one end of the switch is connected to the first output terminal of the drive control chip, and the other end is connected to the input terminal of the turn-on resistor branch. When the switch is in active discharge mode, the switch is configured to be in an open state, and when the switch is in normal operation mode, the switch is configured to be in a closed state, so as to control the opening of the turn-on resistor branch by closing the switch and output a second pulse signal to the turn-on resistor branch.

[0016] Furthermore, the switch may include a MOS transistor.

[0017] As described above, the electric drive system provided by this utility model may specifically include an inverter unit, which may specifically include at least one set of upper and lower bridge arms connected in series. The upper bridge arm includes a gate drive circuit and a switching transistor connected to the output terminal of the gate drive circuit. The gate drive circuit includes an active discharge resistor branch connected in parallel, which is used to turn on the active discharge resistor branch and control the switching transistor to be in a linear state to enter the active discharge mode when an active discharge control signal is received. Since this utility model connects the active discharge resistor branch in parallel to the turn-on resistor branch and sets a switch between the turn-on resistor branch and the drive control chip, when the drive control chip outputs a pulse signal with a small duty cycle, the switch is turned off, allowing only the active discharge resistor branch and the switching transistor to be connected. Based on the pulse signal with a small duty cycle, the characteristic of the switching transistor operating in the linear region when it is in unsaturated state is utilized to actively discharge the bus capacitor through the switching transistor itself, without the need for an additional active discharge circuit, thus reducing the PCB board area and lowering the circuit cost. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the present application and form part of the specification. They are used together with the following detailed description to explain the present application, but do not constitute a limitation thereof. In the drawings:

[0019] Figure 1 This is a circuit diagram of the electric drive system provided in the embodiments of this utility model;

[0020] Figure 2 This is a partial structural diagram of the upper bridge arm provided in an embodiment of the present utility model;

[0021] Figure 3 for Figure 2 The diagram shows a partial structure of the gate drive circuit in the upper bridge arm.

[0022] Figure 4 The diagram shows a partial circuit structure of the switch in the gate drive circuit of the upper bridge arm shown in Figure 2.

[0023] The attached figures are labeled as follows:

[0024] 100-High voltage battery, 200-Bridge inverter, 300-Motor, 210-Bus capacitor, 220-Inverter unit, 221-Upper bridge arm, 2211-Gate drive circuit, 2212-Switch transistor, 2211.1-Drive control chip, 2211.2-Active discharge resistor branch, 2211.3-Turn-on resistor branch, 2211.4-Turn-off resistor branch, 2211.5-Switch. Detailed Implementation

[0025] To make the technical solutions and advantages of the embodiments of this utility model clearer, the technical solutions of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Although exemplary implementation methods of this utility model are shown in the accompanying drawings, it should be understood that this utility model can be implemented in various forms and should not be limited to the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of this utility model and to fully convey the scope of this utility model to those skilled in the art.

[0026] The present invention will be described more specifically by way of example in the following paragraphs with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are in a very simplified form and are only used to facilitate and clarify the illustration of the embodiments of the present invention. It is understood that the meanings of "on," "above," and "over" in the present invention should be interpreted in the broadest sense, such that "on" not only means "on" something without any intervening feature or layer (i.e., directly on something), but also includes "on" something with an intervening feature or layer. In the embodiments of the present invention, the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be noted that the technical solutions described in the embodiments of the present invention can be arbitrarily combined without conflict.

[0027] It should be understood that "common shape" in the embodiments of this utility model refers to the construction of a continuous structural shape by utilizing the morphological similarity and correlation between two or more shapes.

[0028] Those skilled in the art to which this invention pertains will readily understand that, to meet actual product requirements, the electric drive system of this invention may have other forms and is not limited to those described above. Further descriptions will follow regarding other embodiments or variations of the electric drive system of this invention. For the sake of simplicity, identical components in each embodiment of this invention are designated with the same reference numerals to facilitate comparison between embodiments.

[0029] In practical applications, as the power level of new energy vehicles continues to increase, the voltage level of the DC bus voltage of the inverter (inverter unit) is also constantly increasing. The increasingly higher DC bus voltage will inevitably bring greater safety problems. In the case of faults and shutdowns, the excessively high DC bus voltage is a major safety hazard. How to quickly and safely discharge the DC bus capacitor in the case of shutdown or faults is an issue that needs to be paid more and more attention and consideration in the design of new energy vehicles.

[0030] To address this problem, this invention proposes an electric drive system, which may include an inverter unit. Specifically, the inverter unit may include at least one set of upper and lower bridge arms connected in series. The upper bridge arm includes a gate drive circuit and a switching transistor connected to the output of the gate drive circuit. The gate drive circuit includes a parallel-connected active discharge resistor branch, used to activate the active discharge resistor branch and control the switching transistor to a linear state to enter active discharge mode upon receiving an active discharge control signal. Because this invention connects an active discharge resistor branch in parallel to the turn-on resistor branch, and upon turn-on... A switch is installed between the blocking branch and the drive control chip. By controlling the switch to open, only the active discharge resistor branch and the switching transistor are connected. Taking advantage of the characteristic that the switching transistor operates in the linear region when it is not saturated (the switching transistor in the upper bridge arm operates in the linear region during the switching process, which can be equivalent to a variable resistor, thus generating a large switching loss, which causes the energy on the DC bus capacitor to be dissipated as heat on the switching transistor), the switching transistor itself can actively discharge the bus capacitor without the need for an additional active discharge circuit. This reduces the PCB board area and lowers the circuit cost.

[0031] The electric drive system proposed in this utility model will be described in detail below.

[0032] Please refer to Figure 1 and Figure 2 , Figure 1 This is a circuit diagram of the electric drive system provided in the embodiments of this utility model. Figure 2 This is a partial structural diagram of the upper bridge arm provided in an embodiment of the present utility model.

[0033] like Figure 1 and 2As shown, the electric drive system provided by this utility model may include: a high-voltage battery 100, a bridge inverter 200, and a motor 300 connected in sequence; wherein, the bridge inverter 200 may include: a bus capacitor 210 and an inverter unit 220; the bus capacitor 210 is connected to the positive and negative DC bus between the high-voltage battery 100 and the inverter unit 220; the inverter unit 220 is connected in parallel with the two ends of the bus capacitor 210, and includes at least one set of upper bridge arm 221 and lower bridge arm (not shown) connected in series; the upper bridge arm 221 includes: a gate drive circuit 2211 and a switching transistor 2212, and the switching transistor 2212 is connected to the output terminal of the gate drive circuit 2211.

[0034] Specifically, the gate drive circuit 2211 may include a drive control chip 2211.1, an active discharge resistor branch 2211.2, an on-resistor branch 2211.3, an off-resistor branch 2211.4, and a switch 2211.5. The drive control chip 2211.1 includes multiple output terminals, such as a first output terminal and a second output terminal. The first output terminal is connected to both the switch 2211.5 and the input terminal of the active discharge resistor branch 2211.2, for outputting a first pulse signal to the active discharge resistor branch 2211.2 upon receiving the active discharge control signal, and outputting a second pulse signal to the active discharge resistor branch 2211.2 upon receiving the on-resistor signal. The active discharge resistor branch 2211.2 and the on-resistor branch 2211.3 are connected in parallel. The second output terminal of the drive control chip 2211.1 is connected to the input terminal of the off-resistor branch 2211.4.

[0035] The pulse width of the first pulse signal is smaller than that of the second pulse signal. This is controlled by switch 2211.5 to determine whether to enable the active discharge mode (turn-on resistor branch 2211.3 is off) or the normal operation mode (turn-on resistor branch 2211.3 is on). The output of the turn-off resistor branch 2211.4 is connected to the gate of the switching transistor 2212. When the switching transistor 2212 needs to be turned off, it receives a turn-off control signal from the driver control chip 2211.1 and controls the turn-off resistor branch 2211.4 to conduct, while the switching transistor 2212 is in the off state to enter the turn-off mode. For example, the first pulse signal is a pulse signal with a small duty cycle, therefore, in the driving... The control chip 2211.1 outputs the first pulse signal through the first output terminal. The switch 2211.5 is configured to be in the off state, that is, the turn-on resistor branch 2211.3 is not connected to the switch transistor 2212, and only the active discharge resistor branch 2211.2 is connected to the switch transistor 2212. At this time, since the first pulse signal is a pulse signal with a small duty cycle, the switch transistor 2212 is in an unsaturated state and works in the linear region. It is equivalent to a variable resistor at this time. The bus capacitor 210 can be discharged through the switch transistor 2212. That is, the active discharge of the bus capacitor 210 can be achieved by using only some components in the electric drive system itself. The circuit design is simple, the cost is low, and the PCB board area is small.

[0036] Furthermore, one end of the switch 2211.5 is connected to the first output terminal of the drive control chip 2211.1, and the other end is connected to the input terminal of the turn-on resistor branch 2211.3. When the switch transistor 2212 is in active discharge mode, the switch 2211.5 is configured to be in an open state, and when the switch transistor 2212 is in normal operation mode, the switch 2211.5 is configured to be in a closed state, so as to control the turn-on resistor branch 2211 by closing the switch 2211.5. When switch 2211.5 is turned on, it outputs a second pulse signal to the turn-on resistor branch 2211.3. That is, when the drive control chip 2211.1 outputs the second pulse signal through the first output terminal, such as a pulse signal with a large duty cycle, the switch 2211.5 is configured to be in the off state. At this time, the active discharge resistor branch 2211.2 and the turn-on resistor branch 2211.3 are connected in parallel. Since the resistance value after parallel connection is the total resistance value of the resistors in the turn-on resistor branch 2211.3, the switch transistor 2212 can still work normally.

[0037] Please see Figure 3 and Figure 4 , Figure 3 for Figure 2 The diagram shows a partial structural circuit of the gate drive circuit in the upper bridge arm. Figure 4The diagram shows a partial circuit structure of the switch in the gate drive circuit of the upper bridge arm shown in Figure 2. Figure 3 and Figure 4 As shown, the drive control chip 2211.1 can be an S9200. The active discharge resistor branch 2211.2, the turn-on resistor branch 2211.3, and the turn-off resistor branch 2211.4 can all be composed of resistors. For example, the active discharge resistor branch 2211.2 can include multiple active discharge resistors in parallel, such as R1 to Rx. The turn-on resistor branch 2211.3 can include multiple turn-on resistors in parallel, such as Ron1 to RonX. The turn-off resistor branch 2211... 4 may include multiple shut-off resistors, such as Roff1 to RoffX, and the resistance value of the active discharge resistor is N times the resistance value of the turn-on resistor, and 5≤N≤10. The switch 2211.5 includes at least one MOS transistor to control the opening or closing of the turn-on resistor branch 2211.3 by turning the MOS transistor on or off. This configuration can utilize the large resistance value of the active discharge resistor and the characteristic that the switch is equivalent to a variable resistor when it is operating in the unsaturated region to achieve fast and efficient voltage reduction of the bus capacitor.

[0038] It should be noted that the methods, processes, and material descriptions involved in this utility model are all existing technologies used to explain the functionality of the structure or layout proposed in this embodiment.

[0039] In summary, the electric drive system provided by this utility model may specifically include an inverter unit, which may specifically include at least one set of upper and lower bridge arms connected in series. The upper bridge arm includes a gate drive circuit and a switching transistor connected to the output terminal of the gate drive circuit. The gate drive circuit includes an active discharge resistor branch connected in parallel, which is used to turn on the active discharge resistor branch and control the switching transistor to be in a linear state to enter the active discharge mode when an active discharge control signal is received. Because this utility model connects the active discharge resistor branch in parallel to the turn-on resistor branch and sets a switch between the turn-on resistor branch and the drive control chip, when the drive control chip outputs a pulse signal with a small duty cycle, the switch is turned off, allowing only the active discharge resistor branch and the switching transistor to be connected. Based on the pulse signal with a small duty cycle, the characteristic of the switching transistor operating in the linear region when it is in unsaturated state is utilized to actively discharge the bus capacitor through the switching transistor itself, without the need for an additional active discharge circuit, thus reducing the PCB board area and lowering the circuit cost.

[0040] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the scope of protection of the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model are included within the scope of protection of the present utility model.

Claims

1. An electric drive system, characterized in that, It includes a high-voltage battery, a bridge inverter, and a motor connected in sequence, wherein the bridge inverter includes: The bus capacitor is connected to the positive and negative DC bus between the high-voltage battery and the inverter unit; The inverter unit is connected in parallel with the two ends of the bus capacitor and includes at least one set of upper and lower bridge arms connected in series. The upper bridge arm includes a gate drive circuit and a switching transistor connected to the output terminal of the gate drive circuit. The gate drive circuit includes an active discharge resistor branch connected in parallel, which is used to turn on the active discharge resistor branch and control the switching transistor to be in a linear state to enter the active discharge mode when an active discharge control signal is received.

2. The electric drive system as described in claim 1, characterized in that, The gate drive circuit further includes: an on-resistor branch connected in parallel with the active discharge resistor branch, used to turn on and control the switching transistor to be in a saturated state to enter a normal working mode when an on-control signal is received.

3. The electric drive system as described in claim 2, characterized in that, The active discharge resistor branch includes multiple active discharge resistors connected in parallel, and the turn-on resistor branch includes multiple turn-on resistors connected in parallel. The resistance value of the active discharge resistor is greater than the resistance value of the turn-on resistor.

4. The electric drive system as described in claim 3, characterized in that, The resistance value of the active discharge resistor is N times the resistance value of the turn-on resistor, and 5≤N≤10.

5. The electric drive system as described in claim 2, characterized in that, The gate drive circuit further includes: a drive control chip and a shut-off resistor branch; wherein, The drive control chip includes a first output terminal and a second output terminal. The first output terminal is connected to the input terminal of the active discharge resistor branch, so as to output a first pulse signal to the active discharge resistor branch when the active discharge control signal is received, and to output a second pulse signal to the active discharge resistor branch when the turn-on control signal is received. The input terminal of the shut-off resistor branch is connected to the second output terminal of the drive control chip, and the output terminal is connected to the gate of the switching transistor. It is used to control the switching transistor to be in the off state to enter the shut-off mode when a shut-off control signal is received.

6. The electric drive system as described in claim 5, characterized in that, The pulse width of the first pulse signal is smaller than the pulse width of the second pulse signal.

7. The electric drive system as described in claim 6, characterized in that, A switch is provided on the turn-on resistor branch to control the opening or closing of the turn-on resistor branch.

8. The electric drive system as described in claim 7, characterized in that, One end of the switch is connected to the first output terminal of the drive control chip, and the other end is connected to the input terminal of the turn-on resistor branch. When the switch is in active discharge mode, the switch is configured to be in an open state, and when the switch is in normal operation mode, the switch is configured to be in a closed state, so as to control the opening of the turn-on resistor branch by closing the switch and output a second pulse signal to the turn-on resistor branch.

9. The electric drive system as described in claim 8, characterized in that, The switch includes a MOS transistor.

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