Device and method for controlling driving of a switching device of a power converter
By double-processing the gate driving voltage of the switching device in a vehicle driven by an electric motor, the two-level driving strategy is used to solve the conduction loss problem caused by low gate voltage, and the protection of the switching device is achieved. Improvement of inverter efficiency.
Patent Information
- Application Number
- CN202010121276.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2019-06-17
- Filing Date
- 2020-02-26
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2040-02-26
AI Technical Summary
In electric motor-driven vehicles, the low gate voltage of the switching device results in an increase in conduction loss, reducing inverter efficiency, and thus affecting the vehicle fuel efficiency.
By double-changing the gate driving voltage of the switching device into two levels, the switching device is turned on with the first driving voltage and switching to the second driving voltage within the delay time after conduction, reducing the saturation current energy and preventing device damage .
It effectively reduces the saturation current energy of the switching device in the short circuit situation, prevents device damage, and maintains low conduction loss during normal driving, improving inverter efficiency and vehicle fuel efficiency.
Smart Images
Figure CN112104204B_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to an apparatus and method for controlling driving of a switching device of a power converter. Background Art
[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
[0003] Generally, in a vehicle using an electric motor as a driving source, an inverter is provided to generate alternating current (AC) power to be supplied to the electric motor. The inverter includes a power module that controls the current applied from the motor power source, and the power module is composed of switching devices such as insulated gate bipolar transistors (IGBTs).
[0004] The switching device is driven by a voltage applied to its gate terminal so that current can flow between the collector terminal and the emitter terminal of the switching device.
[0005] When the voltage level applied to the gate terminal is low, even if a short circuit occurs in the power module, the amount of current saturated in the switching device decreases due to the physical characteristics of the switching device. As the amount of current saturated in the switching device Isc decreases, the saturation current energy Isc×time that the switching device can tolerate within a predetermined time period decreases, thereby preventing damage to the switching device. Saturation current energy refers to the energy that acts on the inside of the switching device by the current saturated between the collector terminal and the emitter terminal of the switching device during the on-time of the switching device.
[0006] However, lowering the gate voltage hinders efficient driving of the switching device. This is because the lower gate voltage increases the voltage drop between the collector terminal and the emitter terminal of the switching device when current flows in the switching device, resulting in greater conduction losses and, in turn, lowering the efficiency of the inverter, resulting in a negative impact on vehicle fuel efficiency. Summary of the invention
[0007] The present disclosure provides an apparatus and method for controlling the driving of a switching device of a power converter, wherein a driving voltage of a gate terminal of the switching device is provided to the gate terminal and is dualized into two levels, so that when a short circuit occurs in a power module, the switching device can be prevented from being damaged due to current saturation between its collector terminal and emitter terminal.
[0008] In one aspect, the present disclosure provides a device for controlling the drive of a switching device of a power converter, wherein the switching device is turned on by a voltage applied to its gate terminal, the device comprising: a gate driver for applying a first driving voltage and a second driving voltage having different levels to the gate terminal based on a single turn-on of the switching device to turn on the switching device; and a controller for controlling the operation of the gate driver so that after applying the first driving voltage to the gate terminal, the gate driver applies the second driving voltage to the gate terminal.
[0009] In some forms of the present disclosure, the device may have the following features. Specifically, the second drive voltage may be a predetermined level or higher than the first drive voltage. When the switching device is turned on by the first drive voltage, the second drive voltage may be input to the gate terminal of the switching device.
[0010] In some forms of the present disclosure, a gate driver may include a first switch connected between a first gate power supply and a gate terminal, and a second switch connected between a second gate power supply and the gate terminal, wherein the first switch applies a first drive voltage to the gate terminal when turned on, and the second switch applies a second drive voltage to the gate terminal when turned on.
[0011] In some forms of the present disclosure, the controller may turn on the second switch at a predetermined delay time after turning on the first switch. In addition, when the switching device is turned on, the voltage applied between the gate terminal and the emitter terminal of the switching device may be maintained at the first drive voltage during the delay time and then rise to the second drive voltage.
[0012] On the other hand, the present disclosure provides a method for controlling the drive of a switching device of a power converter, wherein the switching device is turned on by a voltage applied to its gate terminal, the method comprising, when the switching device is turned on, applying a first driving voltage to the gate terminal through a gate driver to turn on the switching device, and applying a second driving voltage having a level different from that of the first driving voltage to the gate terminal through the gate driver to change the voltage at the gate terminal to the second driving voltage.
[0013] It should be understood that the term "vehicle" or "vehicular" or other similar terms used herein generally include motor vehicles, such as passenger cars (including sports utility vehicles (SUVs), buses, trucks, various commercial vehicles), watercraft including various ships and ships, aircraft, etc., and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuels from resources other than petroleum). As described herein, a hybrid vehicle is a vehicle having two or more power sources, for example, gasoline-powered and electric vehicles.
[0014] Further areas of applicability will become apparent from the description provided herein.It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In order to better understand the present disclosure, various forms thereof will now be described by way of example with reference to the accompanying drawings, in which:
[0016] Figure 1 is a diagram showing a motor power system of a vehicle;
[0017] Figure 2 is a diagram showing an inverter drive system;
[0018] Figure 3 is a diagram showing a switching device drive control apparatus in one form of the present disclosure;
[0019] Figure 4 is a detailed diagram of a switching device drive control apparatus in one form of the present disclosure;
[0020] Figure 5 is a waveform diagram of a 2-level driving voltage in one form of the present disclosure;
[0021] Fig. 6A is a waveform diagram showing the amount of current saturated in a switching device when a 2-level driving voltage is not applied in one form of the present disclosure; and
[0022] Figure 6B is a waveform diagram showing the amount of current saturated in a switching device when a 2-level driving voltage is applied in one form of the present disclosure.
[0023] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. DETAILED DESCRIPTION
[0024] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
[0025] In a vehicle using an electric motor as a driving source, an inverter may be provided as a power converter that generates alternating current (AC) power to be supplied to the electric motor.
[0026] refer to Figure 1The inverter indicated by reference numeral 3 includes a three-phase power module 31 for controlling the flow of direct current (DC) power applied from a power source 2 for a motor 1 to generate AC power. Each power module 31 is composed of two switching devices 311 connected in series. Each switching device 311 may be an insulated gate bipolar transistor (IGBT), a field effect transistor (FET), etc., which may be turned on under the control of a gate-emitter voltage Vge.
[0027] Each switching device 311 has a gate terminal G to which a driving voltage is applied, and a collector terminal C and an emitter terminal E, and when the driving voltage is applied to the gate terminal G, the collector terminal C and the emitter terminal E become conductive so that current flows therebetween. In the switching device 311, when the driving voltage is applied to the gate terminal G, conduction can be performed between the collector terminal C and the emitter terminal E. In other words, in the switching device 311, when a predetermined driving voltage is applied to the gate-emitter circuit of the switching device 311, conductivity can be provided to the collector-emitter portion, so that current can flow therein. That is, when the driving voltage is applied to the gate terminal G, the switching device 311 can be turned on, and thus conduction can be performed between the collector terminal C and the emitter terminal E.
[0028] refer to Figure 2 and 3 , the gate terminal G can receive a driving voltage through the gate driver 4, and the gate driver 4 can be controlled by the controller 6. The controller 6 can be a motor control unit (MCU) of the vehicle, which controls the motor. In addition, the gate terminal G can be connected to the gate power supply 51, 52, and the gate power supply 51, 52 provides a driving voltage through the gate driver 4.
[0029] In addition, in Figure 1 In the motor power system shown, the collector terminal C can be connected to the positive terminal of the power source 2 , and the emitter terminal E can be connected to the negative terminal of the power source 2 .
[0030] For reference, in Figure 3 In the embodiment, the diode 312 connected in parallel with the collector terminal C and the emitter terminal E of the switching device 311 may be a freewheeling diode with a short turn-off time. The freewheeling diode 312 may be selectively connected to the switching device 311 to enhance the reverse cut-off performance of the switching device 311.
[0031] When the voltage level applied to the gate terminal G is low, even if a short circuit occurs in the power module 31, the amount of current saturated in the switching device 311 decreases due to the physical characteristics of the switching device 311. As the amount of current Isc saturated in the switching device 311 decreases, the saturation current energy Isc×time that the switching device 311 can tolerate within a predetermined period of time decreases, thereby preventing the switching device 311 from being damaged.
[0032] However, lowering the gate-emitter voltage Vge of the switching device 311 hinders efficient driving of the switching device 311. This is because when current flows in the switching device 311, due to the low gate-emitter voltage Vge, the voltage drop Vce generated between the collector terminal C and the emitter terminal E of the switching device 311 increases, resulting in a larger amount of conduction loss of the switching device 311, and thus reducing the efficiency of the inverter 3, resulting in a negative impact on the fuel efficiency of the vehicle.
[0033] Therefore, some forms of the present disclosure provide a drive control device for the switching device 311, which controls the driving of the switching device 311 by doubling the driving voltage of the gate terminal G of the switching device 311 to two levels. The drive control device can apply the driving voltage for turning on the switching device 311 to the gate terminal at two levels, thereby preventing the switching device 311 from being damaged due to current saturation between its collector terminal C and emitter terminal E when a short circuit occurs in the power module 31.
[0034] like Figure 3 As shown, the drive control device includes a gate driver 4 that applies a drive voltage to a gate terminal G of the switching device 311 and a controller 6 that controls the operation of the gate driver 4 .
[0035] The gate driver 4 may be disposed between the gate power supplies 51, 52 and the gate terminal G of the switching device 311. The gate driver 4 may selectively apply the driving voltage output from the gate power supplies 51, 52 to the gate terminal G to turn on the switching device 311. That is, the gate driver 4 may be configured to apply the driving voltage to the gate terminal G by pulse width modulation (PWM). The driving voltage may be controlled to be output in the form of a square wave signal and applied to the gate terminal G.
[0036] The gate driver 4 may double the driving voltage into two levels and sequentially input the generated two-level voltages to the gate terminal G. That is, the gate driver 4 may apply the first driving voltage and the second driving voltage having different levels to the gate terminal G.
[0037] like Figure 4 As shown, in order to output the driving voltage to the gate terminal G at two levels, the gate driver 4 may include a first switch 41 and a second switch 42 which are controlled to be turned on / off by the controller 6 .
[0038] The first switch 41 may be connected between the first gate power source 51 and the gate terminal G to apply the first driving voltage to the gate terminal G. The second switch 42 may be connected between the second gate power source 52 and the gate terminal G to apply the second driving voltage to the gate terminal G.
[0039] The first gate power supply 51 may be configured to output a first driving voltage, and when turned on by the controller 6, the first switch 41 may input the first driving voltage to the gate terminal G. The first switch 41 may be a normally open type electronic switch that is closed when changed to an on state by the controller 6. When the first switch 41 is turned on, when closed, conduction may be conducted between the first gate power supply 51 and the gate terminal G, so that current may flow therebetween.
[0040] The second gate power supply 52 may be configured to output a second driving voltage, and when turned on by the controller 6, the second switch 42 may input the second driving voltage to the gate terminal G. The second switch 42 may be a normally open type electronic switch that is closed when changed to an on state by the controller 6. When the second switch 42 is turned on, conduction may be conducted between the second gate power supply 52 and the gate terminal G when closed.
[0041] The level of the first driving voltage is different from the level of the second driving voltage. That is, the first driving voltage may be lower than the second driving voltage by a predetermined reference voltage or higher. In other words, the second driving voltage may be higher than the first driving voltage by a reference voltage or higher. The second driving voltage is set to a level that can normally turn on the switching device 311, and the first driving voltage is set to a level that is lower than the second driving voltage but can normally turn on the switching device 311. In addition, the second driving voltage is set to a level that can normally maintain the on-state of the switching device 311, and the first driving voltage is set to a level that can reduce the amount of saturated current in the switching device 311, but will not cause an increase in the switching loss and conduction loss of the switching device 311. For example, the first driving voltage may be 12V, and the second driving voltage may be 15V. In this case, the reference voltage may be 3V.
[0042] The controller 6 controls the switching operation of the gate driver 4 so that the first driving voltage is applied to the gate terminal G, and then the second driving voltage is applied to the gate terminal G. For this reason, when driving the first switch 41 and the second switch 42, the controller 6 first turns on the first switch 41, and then turns on the second switch 42 after a predetermined delay time. That is, the controller 6 drives the first switch 41 at the turn-on time of the switching device 311, and then drives the second switch 42 after the delay time has passed from the turn-on time. In other words, the controller 6 drives the second switch 42 after a certain time is delayed from the turn-on time of the switching device 311. The delay time can be set to a short time in which the conduction loss of the switching device 311 turned on by the first driving voltage does not increase.
[0043] In this way, the driving voltage applied to the gate terminal G can be applied at two levels (see Figure 5). Based on the one-time conduction of the switching device 311, when the switching device 311 starts to be turned on, the first drive voltage is applied to the gate terminal G, and then after the delay time from the application of the first drive voltage to the gate terminal G has passed, the second drive voltage is applied to the gate terminal G. In the case where the switching device 311 is turned on, the second drive voltage is applied to the gate terminal G. That is, in the case where the first drive voltage is applied to the gate terminal G, a second drive voltage higher than the first drive voltage is applied to the gate terminal G. In other words, the switching device 311 receives the second drive voltage after being changed to the on state by the first drive voltage. As a result, when the switching device 311 is turned on, the voltage between its gate terminal G and the emitter terminal E (gate-emitter voltage Vge) is maintained at the first drive voltage during the delay time, and then rises to the second drive voltage.
[0044] The switching device 311 is turned on by the first driving voltage and is kept turned on by the second driving voltage. Therefore, at the beginning of the switching device 311 turning on, a collector current Ic smaller than the amount before the second driving voltage is applied to the gate terminal G flows between the collector terminal C and the emitter terminal E, and the amount of saturation current (saturation current amount) between the collector terminal C and the emitter terminal E is relatively small (see Fig. 6A and Figure 6B ). In other words, the saturation current amount of the switching device 311 when the first driving voltage and the second driving voltage are sequentially applied to the gate terminal G to turn on the switching device 311 is smaller than the saturation current amount when only the second driving voltage is applied to the gate terminal G to turn on the switching device 311. The saturation current amount is the current amount saturated between the collector terminal C and the emitter terminal E for the time that the switching device 311 once turns on and remains turned on.
[0045] Therefore, even if a short circuit occurs in the power module 31 including the switching device 311, the amount of current saturated between the collector terminal C and the emitter terminal E of the switching device 311 is relatively reduced, so that the saturation current energy that causes damage to the switching device 311 is reduced. As a result, even when a short circuit occurs in the power module 31, the switching device 311 can be prevented from being damaged. In other words, when only the first drive voltage is applied to the gate terminal G, a collector current Ic that is less than the amount when the second drive voltage is applied to the gate terminal G flows, so that the amount of saturation current between the collector terminal C and the emitter terminal E is relatively small. As the amount of saturation current decreases, the saturation current energy of the switching device 311 decreases, thereby preventing it from being damaged.
[0046] On the other hand, when a short circuit is not generated in the power module 31, the switch device 311 is turned on by the first drive voltage only during the delay time, and is kept turned on by the second drive voltage after the delay time. Therefore, the switch device 311 can be driven normally without causing an increase in conduction loss. In addition, in a normal case where a short circuit is not generated in the power module 31, a sufficient amount of collector current Ic flows due to the application of the first drive voltage to the gate terminal G, so that the switch device 311 is driven normally.
[0047] In addition, when a 2-level driving voltage is applied to the gate terminal G (see Figure 6B ), the saturation current between the collector terminal C and the emitter terminal E is greater than when a 1-level drive voltage is applied to the gate terminal G (see Fig. 6A ) decreases, and the rising slope of the voltage Vsense sensed at the emitter terminal E also decreases accordingly.
[0048] The switching device drive control apparatus having the above configuration controls the drive voltage to the switching device 311 at two levels. Therefore, when the switching device 311 is turned on, the amount of saturated current in the switching device 311 is reduced, so that when a short circuit occurs in the power module 31, the switching device 311 can be prevented from being damaged and the power module 31 can be protected.
[0049] Furthermore, since the drive control device controls the drive voltage of the switching device 311 at two levels, it is possible to prevent an increase in the conduction loss of the switching device 311 due to an increase in the voltage drop Vce between the collector terminal C and the emitter terminal E of the switching device 311. Furthermore, it is possible to prevent a decrease in the efficiency of the inverter 3 due to an increase in the conduction loss of the switching device 311, thereby preventing a decrease in the fuel efficiency of the vehicle.
[0050] As apparent from the above description, some forms of the present disclosure provide an apparatus and method for controlling driving of a switching device of a power converter, wherein a driving voltage of a gate terminal of the switching device is controlled at two levels.
[0051] The switching device drive control device drives the switching device with a relatively low level first drive voltage in the initial conduction stage when the switching device changes to the conduction state and starts driving, and drives the switching device with a relatively high level second drive voltage at a predetermined time after the switching device is turned on. Therefore, when a short circuit occurs in the power module, the amount of current saturated between the collector terminal and the emitter terminal of the switching device is reduced, thereby preventing the switching device from being damaged due to the saturation current. When the power module is driven normally, the conduction characteristics of the power converter can be provided, which are similar to those in the conventional case (i.e., the case where the gate-emitter voltage is not controlled at two levels).
[0052] The description of the present disclosure is merely exemplary in nature, and thus, variations that do not depart from the essence of the present disclosure are intended to be within the scope of the present disclosure. Such variations should not be regarded as departing from the spirit and scope of the present disclosure.
Claims
1. A device for controlling a switching device of a power converter, in, The switching device is turned on by a voltage applied to a gate terminal of the switching device, the apparatus comprising: The gate driver is configured as: applying a first driving voltage and a second driving voltage to the gate terminal based on one turn-on of the switching device, wherein the first driving voltage and the second driving voltage have different values; and turning on the switching device; and A controller is configured to control the gate driver so that the gate driver applies the second driving voltage to the gate terminal after the first driving voltage is applied to the gate terminal.
2. The device according to claim 1, in, The second driving voltage is greater than the first driving voltage by a predetermined value.
3. The device according to claim 1, in, The gate driver comprises: a first switch connected between a first gate power source and the gate terminal, and configured to apply the first driving voltage to the gate terminal when the first switch is turned on; and A second switch is connected between a second gate power source and the gate terminal, and the second switch is configured to apply the second driving voltage to the gate terminal when the second switch is turned on.
4. The device according to claim 3, in, The controller is configured to: turning on the first switch; and When the first switch is turned on, the second switch is turned on after a predetermined amount of time.
5. The device according to claim 4, in, When the switching device is turned on, the voltage applied between the gate terminal and the emitter terminal is maintained at the first driving voltage for the predetermined amount of time, and the voltage applied between the gate terminal and the emitter terminal is increased to the second driving voltage.
6. The device according to claim 1, in, When the switching device is turned on by the first driving voltage, the second driving voltage is input to the gate terminal.
7. A method for controlling a switching device of a power converter, in, The switching device is turned on by a voltage applied to a gate terminal of the switching device, the method comprising: Applying a first driving voltage to the gate terminal by a gate driver to turn on the switching device; When the switching device is turned on, the gate driver applies a second driving voltage to the gate terminal, wherein the first driving voltage and the second driving voltage have different values; and The voltage at the gate terminal is changed to the second driving voltage.
8. The method according to claim 7, in, The second driving voltage is greater than the first driving voltage by a predetermined value.
9. The method according to claim 7, in, The method further comprises: When a first switch is turned on, the first drive voltage is applied to the gate terminal by the first switch, wherein the first switch is connected between a first gate power supply and the gate terminal; and When the second switch is turned on, the second driving voltage is applied to the gate terminal by the second switch, wherein the second switch is connected between a second gate power source and the gate terminal.
10. The method according to claim 9, in, The method further comprises: The controller turns on the first switch; and When the first switch is turned on, the second switch is turned on by the controller after a predetermined amount of time.
11. The method according to claim 10, in, The method further comprises: When the switching device is turned on, the voltage applied between the gate terminal and the emitter terminal is maintained at the first driving voltage for the predetermined amount of time; and The voltage applied between the gate terminal and the emitter terminal is increased to the second driving voltage.
12. The method according to claim 7, in, The method further comprises: When the switching device is turned on by the first driving voltage, the second driving voltage is input to the gate terminal.