Current source driving circuit and control method

Abstract

The invention discloses a current source driving circuit and a control method, and belongs to the field of power electronics. The current source driving circuit comprises a charging current source driving circuit, a discharging current source driving circuit, a charging current source control voltage regulation and control circuit and a discharging current source control voltage regulation and control circuit, the charging current source driving circuit adopts a P-MOS tube M1, and the source electrode is connected with a positive power supply VCC; the discharge current source driving circuit adopts an N-MOS tube M2, and a source electrode is connected with a negative power supply VEE; drain electrodes of the M1 and the M2 are connected with a grid electrode G of the driven power device T1, and grid electrodes are connected with output ends of the corresponding voltage regulation and control circuits; in the transient state process of the T1 switch, the output voltages vctrl1 and vctrl2 of the voltage regulation and control circuit are controlled to control M1 and M2 to work in a saturation region, and the output on and off driving current is dynamically regulated and controlled; and after the transient state of the T1 switch is finished, the vctrl1 and the vctrl2 control the M1 and the M2 to work in a variable resistance region, and the T1 gate-source voltage clamp is located in VCC and VEE. The whole circuit is simple in structure and high in driving current adjusting speed.

Description

Technical Field

[0001] The present invention belongs to the field of power electronics, and more specifically, relates to a current source drive circuit and a control method. Background Art

[0002] Power electronic converters are key devices for achieving efficient conversion of electric energy, and play a key role in rail transit, new energy and new power systems. As the core component of the converter, the working characteristics of the power switching device directly affect the key performance of the converter, such as efficiency, power density and reliability. The gate drive circuit of the power switching device has a significant impact on the working performance of the device, such as device loss and reliability. Compared with the traditional voltage source drive circuit, the current source drive circuit can provide a constant drive current during the switching transient of the power device, thereby accelerating the input capacitor charging / discharging process and reducing the switching loss of the power device. However, the current current source drive circuit has a complex structure and a slow switching speed of the drive current, which is not suitable for power switching devices with fast switching transients.

[0003] The current current source drive circuit implementation technology can be mainly divided into three categories: 1) Inductor-based resonant current source, which uses the characteristic of inductance to hinder current changes to provide a constant drive current, but due to the presence of inductance, this method has a slow drive current adjustment speed; 2) BJT-based mirror current source, which connects two BJTs with completely identical parameters into a current mirror structure, and dynamically adjusts the drive current by adjusting the reference current source of the current mirror, but this method has overshoot during the current switching process and a slow adjustment speed; 3) Current source based on multiple MOSFET branches in parallel, which adjusts the drive current by controlling the number of MOSFET branches that are turned on, but the MOSFET in each branch needs to be equipped with corresponding control and trigger circuits, making the circuit structure too complicated, difficult to implement and costly. In summary, the existing current source drive circuit has a slow drive current adjustment speed and a complex circuit implementation scheme. Summary of the invention

[0004] In view of the defects of the related art, the purpose of the present invention is to provide a current source driving circuit and a control method, aiming to solve the problems of slow adjustment speed and complex structure of the current source driving circuit of the existing power device.

[0005] To achieve the above-mentioned object, in a first aspect, the present invention provides a current source driving circuit, wherein the driven power device T1 is a SiC MOS, including a gate G, a drain D, a source S and a Kelvin source KS; characterized in that the current source driving circuit includes: a charging current source driving circuit, a discharging current source driving circuit, a charging current source control voltage regulation circuit and a discharging current source control voltage regulation circuit;

[0006] The charging current source driving circuit adopts a P-MOS tube M1, and the source of the P-MOS tube M1 is connected to the positive power supply V CC The drain is connected to the gate G of the driven power device T1, and the gate is connected to the output end of the charging current source control voltage regulation circuit; the charging current source driving circuit is used to provide the driving current required for the transient process of turning on the driven power device T1 and the gate-source bias voltage V of T1 when turning on the steady state CC ;

[0007] The discharge current source driving circuit adopts an N-MOS tube M2, the source of the N-MOS tube M2 is connected to the negative power supply V EE The drain is connected to the gate G of the driven power device T1, and the gate is connected to the output end of the discharge current source control voltage regulation circuit; the discharge current source driving circuit is used to provide the driving current required for the transient shutdown process of the driven power device T1 and the gate-source bias voltage V of T1 when it is turned off in a steady state EE ;

[0008] The charging current source controls the output voltage v of the voltage control circuit ctrl1 , used to regulate the gate-source voltage v of the P-MOS tube M1 GS1 , so that when the driven power device T1 is turned on transiently, the P-MOS tube M1 is controlled to work in the saturation region to dynamically adjust the turn-on drive current output by M1; and when the driven power device T1 is turned on steady state, the P-MOS tube M1 is controlled to work in the variable resistance region to clamp the gate-source voltage of the driven power device T1 to the turn-on steady-state bias voltage V CC ;

[0009] The discharge current source controls the output voltage v of the voltage control circuit ctrl2 , used to regulate the gate-source voltage v of the N-MOS tube M2 GS2 , so that when the driven power device T1 is turned off transiently, the N-MOS tube M2 is controlled to work in the saturation region to dynamically adjust the turn-off drive current output by M2; and when the driven power device T1 is turned off steadily, the N-MOS tube M2 is controlled to work in the variable resistance region to clamp the gate-source voltage of the driven power device T1 to the turn-off steady-state bias voltage V EE .

[0010] Optionally, the positive power supply is 15V and the negative power supply is -5V.

[0011] Optionally, the charging current source control voltage regulation circuit includes an FPGA and a first DAC;

[0012] The digital signal output terminal of the FPGA is connected to the digital signal input terminal of the first DAC, and the analog signal output terminal of the first DAC is connected to the gate of the P-MOS tube M1.

[0013] Optionally, the discharge current source control voltage regulation circuit includes the FPGA and a second DAC;

[0014] The digital signal output terminal of the FPGA is connected to the digital signal input terminal of the second DAC, and the analog signal output terminal of the second DAC is connected to the gate of the N-MOS tube M2.

[0015] In a second aspect, the present invention further provides a control method for a current source driving circuit, which is executed based on the circuit described in any one of the first aspects, wherein within one cycle, the driven power device T1 includes a turn-on process and a turn-off process; the control method includes:

[0016] S1, before the driven power device T1 is in the turn-on process, the charging current source controls the output voltage v of the voltage control circuit ctrl1 is the positive bias voltage V CC ; Among them, the positive bias voltage V CC A gate-source bias voltage that turns on a steady-state for the driven power device T1;

[0017] S2, at time t0, the charging current source controls the output voltage v of the voltage control circuit ctrl1 From the positive bias voltage V CC Switch to voltage V p1 , maintain voltage V p1 To time t1;

[0018] S3, at time t1, the charging current source controls the output voltage v of the voltage control circuit ctrl1 Increase to V p2 , and maintain until time t2; where V p1 Less than V p2 , V p1 and V p2 The range of values ​​makes the P-MOS tube M1 used in the charging current source driving circuit work in the saturation region;

[0019] S4, at time t2, the charging current source controls the output voltage v of the voltage control circuit ctrl1 Switch to V p1 , maintain voltage V p1 To time t4;

[0020] S5. At time t4, the charging current source controls the output voltage v of the voltage control circuit. ctrl1 Switch to V p3, until the driven power device T1 starts to turn off; where V p3 The range of values ​​makes the P-MOS tube M1 used in the charging current source driving circuit work in the variable resistance area;

[0021] S6, at time t5 before the driven power device T1 is turned off, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 is the negative bias voltage V EE ; Among them, the negative bias voltage V EE is the gate-source bias voltage of the driven power device T1 when it is turned off in the steady state;

[0022] S7, at time t5, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 From the negative bias voltage V EE Switch to voltage V n1 , maintain voltage V n1 To time t7;

[0023] S8, at time t7, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 Stepwise decrease to V n2 , and maintain until time t8; where V n1 Greater than V n2 , V n1 and V n2 The range of values ​​makes the N-MOS tube M2 used in the discharge current source driving circuit work in the saturation region;

[0024] S9, at time t8, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 Switch to V n1 , maintain voltage V n1 Until t9;

[0025] S10, at time t9, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 Switch to V n3 , and is maintained until the next cycle of the driven power device T1 begins. Among them, V n3 The range of values ​​makes the N-MOS tube M2 used in the discharge current source driving circuit work in the variable resistance area.

[0026] In a third aspect, the present invention further provides a double pulse test circuit, comprising: a high voltage DC power supply V1, a DC bus capacitor C1, a load inductor L1, a freewheeling diode D1, a driven power device T1, and a current source drive circuit as described in any one of the first aspects;

[0027] The high-voltage DC power supply V1 and the DC bus capacitor C1 are connected in parallel;

[0028] The load inductor L1 and the freewheeling diode D1 are connected in parallel, and the anode of the freewheeling diode D1 is connected to the drain D of the driven power device T1;

[0029] The source electrode S of the driven power device T1 is connected to the negative electrode of the high voltage DC power supply V1;

[0030] The cathode of the freewheeling diode D1 is connected to the anode of the high voltage DC power supply V1;

[0031] The driven power device T1 is connected to the current source driving circuit, and is turned on or off according to the on / off driving current output by the current source driving circuit.

[0032] Optionally, the driven power device T1 is a three-pin device or a four-pin device;

[0033] When the driven power device T1 is a three-pin device, the Kelvin source KS and the source S are regarded as the same point.

[0034] Compared with the prior art, the above technical solution conceived by the present invention can achieve the following beneficial effects:

[0035] 1. The present invention provides a current source driving circuit. The charging current source driving circuit only uses one P-MOSFET, and the discharging current source driving circuit only uses one N-MOSFET, so as to form a current source driving circuit. The output voltages of the charging current source control voltage regulation circuit and the discharging current source control voltage regulation circuit are used to regulate the working states of the MOSFETs in the charging current source driving circuit and the discharging current source driving circuit respectively, so as to realize the control of the driving current in the transient process of turning on and off the driven power device T1 and the clamping of the gate-source voltage in the steady-state process of turning on and off. The overall circuit structure is simple, easy to realize and has lower cost.

[0036] 2. The present invention provides a control method for a current source driving circuit. By regulating the output voltage of the charging current source control voltage control circuit and the discharging current source control voltage control circuit, the gate-source voltage of the MOSFET in the current source driving circuit is regulated to achieve dynamic regulation of the driving current during the switching transient of the power device T1. The regulation method is simpler and the driving current regulation speed of the method is faster, and it can be applied to wide bandgap power devices with fast switching transients. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A comparison diagram of a current source driving method and a conventional voltage source driving method;

[0038] Figure 2A block diagram of a current source driving circuit provided by an embodiment of the present invention;

[0039] Figure 3 A specific circuit connection diagram of a current source driving circuit provided by an embodiment of the present invention;

[0040] Figure 4 A control principle diagram of an N-MOS tube M2 in a current source driving circuit provided by the present invention;

[0041] Figure 5 A control principle diagram of a P-MOS tube M1 in a current source driving circuit provided by the present invention;

[0042] Figure 6 It is a timing diagram of the turn-on process of a fast switching dynamic current source drive circuit;

[0043] Figure 7 It is a timing diagram of the shut-down process of a fast switching dynamic current source drive circuit;

[0044] Figure 8 A schematic diagram of a switching waveform of an output drive current of an inductor-based resonant current source circuit;

[0045] Fig. 9 A schematic diagram of a switching waveform of an output drive current of a BJT-based mirror current source circuit;

[0046] Fig.10 The diagram is a schematic diagram of a switching waveform of a driving current output by a fast switching current source circuit proposed by the present invention. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0048] The contents involved in the above embodiment are described below in conjunction with a preferred embodiment.

[0049] Embodiment 1

[0050] like Figure 1 As shown, Figure 1 A comparison chart of a current source driving method and a conventional voltage source driving method.

[0051] During the turn-on transient process of the driven power device, when the voltage source driving method is adopted, as the gate-source voltage of the driven power device increases, the driving current gradually decreases, resulting in a larger turn-on delay and turn-on loss. When the current source driving method is adopted, as the gate-source voltage of the driven power device increases, the driving current can be maintained constant, so that the gate-source voltage of the driven power device rises faster, achieving a smaller turn-on delay and turn-on loss. Furthermore, during the turn-off transient process of the driven power device, the current source driving method can also achieve a smaller turn-off delay and turn-off loss.

[0052] like Figure 2 and Figure 3 As shown, the present invention provides a current source driving circuit, the driven power device T1 is SiCMOS, including a gate G, a drain D, a source S and a Kelvin source KS; the current source driving circuit includes: a charging current source driving circuit, a discharging current source driving circuit, a charging current source control voltage regulation circuit and a discharging current source control voltage regulation circuit;

[0053] The charging current source driving circuit adopts a P-MOS tube M1, and the source of the P-MOS tube M1 is connected to the positive power supply V CC The drain is connected to the gate G of the driven power device T1, and the gate is connected to the output end of the charging current source control voltage regulation circuit; the charging current source driving circuit is used to provide the driving current required for the transient process of turning on the driven power device T1 and the gate-source bias voltage V of T1 when turning on the steady state CC ;

[0054] The discharge current source driving circuit adopts an N-MOS tube M2, the source of the N-MOS tube M2 is connected to the negative power supply V EE The drain is connected to the gate G of the driven power device T1, and the gate is connected to the output end of the discharge current source control voltage regulation circuit; the discharge current source driving circuit is used to provide the driving current required for the transient shutdown process of the driven power device T1 and the gate-source bias voltage V of T1 when it is turned off in a steady state EE ;

[0055] The charging current source controls the output voltage v of the voltage control circuit ctrl1 , used to regulate the gate-source voltage v of the P-MOS tube M1 GS1 , so that when the driven power device T1 is turned on transiently, the P-MOS tube M1 is controlled to work in the saturation region to dynamically adjust the turn-on drive current output by M1; and when the driven power device T1 is turned on steady state, the P-MOS tube M1 is controlled to work in the variable resistance region to clamp the gate-source voltage of the driven power device T1 to the turn-on steady-state bias voltage V CC ;

[0056] The discharge current source controls the output voltage v of the voltage control circuit ctrl2 , used to regulate the gate-source voltage v of the N-MOS tube M2 GS2 , so that when the driven power device T1 is turned off transiently, the N-MOS tube M2 is controlled to work in the saturation region to dynamically adjust the turn-off drive current output by M2; and when the driven power device T1 is turned off steadily, the N-MOS tube M2 is controlled to work in the variable resistance region to clamp the gate-source voltage of the driven power device T1 to the turn-off steady-state bias voltage V EE .

[0057] The present invention provides a current source driving circuit, which is regulated based on the gate voltage of MOSFET in the saturation region, and overcomes the defects existing in the existing current source driving circuit implementation technology. The current source driving circuit uses a MOSFET to provide the driving current required for the power device shutdown process, and uses another MOSFET to provide the driving current required for the power device turn-on process. By controlling the gate voltage of the above-mentioned MOSFET to make it work in the saturation region, a constant current is provided, and by dynamically regulating the gate voltage of the above-mentioned MOSFET to change its operating point, the rapid regulation of the driving current is achieved, and the circuit structure is simple and the current regulation speed is fast. In addition, in the steady-state process of turning on and off the driven power device T1, by controlling the gate voltage of the above-mentioned MOSFET to make it work in the variable resistance region, the gate-source voltage of T1 is clamped at the steady-state bias voltage of turning on and off.

[0058] like Figure 2 As shown, the driven power device T1 adopts SiC MOS, which has four connection terminals, including gate G, drain D, source S and Kelvin source KS; the capacitor C connected between the gate G and the Kelvin source KS GS is the gate-source capacitance of the driven power device T1; capacitance C GS The voltage is the gate voltage of the driven power device T1, recorded as the driving voltage v GS ; The current flowing into the gate G of the driven power device T1 is recorded as the driving current i G ; The threshold voltage of the driven power device T1 is recorded as V th , Miller platform voltage is recorded as V miller ; The drain-source voltage of the driven power device T1 is recorded as v DS , the drain current is recorded as i D .

[0059] like Figure 3 As shown, the charging current source driving circuit is driven by the positive power supply V CC The source of the P-MOS tube M1 is connected to the positive power supply V CCThe drain is connected to the gate G of the driven power device T1, and the gate is connected to the output end of the charging current source control voltage regulation circuit.

[0060] like Figure 3 As shown, the discharge current source driving circuit is driven by a negative power supply V EE The source of N-MOS tube M2 is connected to the negative power supply V EE The drain is connected to the gate G of the driven power device T1, and the gate is connected to the output end of the discharge current source control voltage regulation circuit.

[0061] Among them, during the turn-on and turn-off transient process of the driven power device T1, the P-MOS tube M1 and the N-MOS tube M2 should work in the device saturation region to provide a constant current to the gate G terminal of the driven power device T1; during the turn-on and turn-off steady-state process of the driven power device T1, the P-MOS tube M1 and the N-MOS tube M2 should work in the device variable resistance region to clamp the gate-source voltage of T1 at the turn-on and turn-off steady-state bias voltage.

[0062] In this embodiment, the positive power supply is 15V, and the negative power supply is -5V.

[0063] The charging current source controls the output voltage v of the voltage control circuit ctrl1 and the discharge current source controls the output voltage v of the voltage control circuit ctrl2 With dynamic regulation capability, the output voltage v ctrl1 and the output voltage v ctrl2 The magnitude of the output drive current is adjusted dynamically according to the control signal. Specifically, it includes:

[0064] (1) During the turn-on transient of the driven power device T1, when the gate-source voltage v GS Located in V miller With V th When the charging current source controls the output voltage v of the voltage control circuit ctrl1 It should be increased in stages to reduce the drain current of the P-MOS tube M1, thereby reducing the driving current output by the charging current source driving circuit, and further reducing the drain current change rate di of the driven power device T1. D / dt, thereby reducing the current stress of T1.

[0065] (2) During the turn-off transient of the driven power device T1, when the gate-source voltage v GS Located in V miller With V thWhen the discharge current source controls the output voltage of the voltage regulation circuit, the output voltage should be reduced in stages to reduce the drain current of the N-MOS tube M2, thereby reducing the drive current output by the discharge current source drive circuit, and further reducing the drain current change rate di of the driven power device T1. D / dt, thereby reducing the voltage stress of T1.

[0066] Optionally, the charging current source control voltage regulation circuit includes an FPGA and a first DAC;

[0067] The digital signal output terminal of the FPGA is connected to the digital signal input terminal of the first DAC, and the analog signal output terminal of the first DAC is connected to the gate of the P-MOS tube M1.

[0068] Furthermore, the charging current source control voltage regulation circuit is composed of an FPGA, a first DAC and a first peripheral circuit; the first peripheral circuit is connected one by one according to the configuration scheme required for the normal operation of the FPGA and the first DAC.

[0069] Optionally, the discharge current source control voltage regulation circuit includes the FPGA and a second DAC;

[0070] The digital signal output terminal of the FPGA is connected to the digital signal input terminal of the second DAC, and the analog signal output terminal of the second DAC is connected to the gate of the N-MOS tube M2.

[0071] Furthermore, the discharge current source control voltage regulation circuit is composed of an FPGA, a second DAC and a second peripheral circuit; the second peripheral circuit is connected one by one according to the configuration scheme required for the normal operation of the FPGA and the second DAC.

[0072] The control principle diagram of the N-MOS tube M2 in the current source driving circuit provided by the present invention is as follows: Figure 4 As shown, specifically, during the shutdown transient process of the driven power device T1, the output signal v of the discharge current source control voltage control circuit ctrl2 The N-MOS tube M2 should be operated in the saturation region to provide a constant driving current for the driven power device T1; when the output signal v of the discharge current source control voltage control circuit ctrl2 When the gate-source voltage v of N-MOS tube M2 changes, GS2 changes, causing its operating point to change, and the drain current i D2 Therefore, v ctrl2 The driving current output by the discharge current source driving circuit can be directly controlled to achieve segmented dynamic regulation of the driving current during the shutdown transient process of the driven power device T1.

[0073] The control principle diagram of the P-MOS tube M1 in the current source driving circuit provided by the present invention is as follows: Figure 5 As shown, specifically, during the turn-on transient process of the driven power device T1, the output signal v of the charging current source control voltage control circuit ctrl1 The P-MOS tube M1 should be operated in the saturation region to provide a constant driving current for the driven power device T1; when the output signal v of the charging current source control voltage control circuit ctrl1 When the gate-source voltage v of the P-MOS tube M1 changes, GS1 changes, causing its operating point to change, and the drain current i D1 Therefore, v ctrl1 The driving current output by the charging current source driving circuit can be directly controlled to achieve segmented dynamic regulation of the driving current during the transient process of turning on the driven power device T1.

[0074] The embodiment of the present invention provides a current source driving circuit. The charging current source driving circuit only uses one P-MOSFET, and the discharging current source driving circuit only uses one N-MOSFET, so as to form a current source driving circuit. The driving current output by the charging current source driving circuit and the discharging current source driving circuit are regulated by controlling the output voltage of the charging current source control voltage regulation circuit and the discharging current source control voltage regulation circuit respectively. The problems of slow regulation speed and complex structure existing in the existing current source driving circuit of power devices are solved. The segmented dynamic regulation of the driving current in the turn-on transient process and the turn-off transient process of the driven power device T1 is realized. The overall circuit structure is simple, the driving current regulation speed is fast, it is easy to implement and the cost is lower.

[0075] Embodiment 2

[0076] The present invention further provides a control method for a current source driving circuit, which is executed based on the circuit described in any one of the first embodiments. In one cycle, the driven power device T1 includes a turn-on process and a turn-off process. The control method includes:

[0077] S1, before the driven power device T1 is in the turn-on process, the charging current source controls the output voltage v of the voltage control circuit ctrl1 is the positive bias voltage V CC ; Among them, the positive bias voltage V CC A gate-source bias voltage that turns on a steady-state for the driven power device T1;

[0078] S2, at time t0, the charging current source controls the output voltage v of the voltage control circuit ctrl1 From the positive bias voltage V CC Switch to voltage V p1 , maintain voltage V p1To time t1;

[0079] S3, at time t1, the charging current source controls the output voltage v of the voltage control circuit ctrl1 Increase to V p2 , and maintain until time t2; where V p1 Less than V p2 , V p1 and V p2 The range of values ​​makes the P-MOS tube M1 used in the charging current source driving circuit work in the saturation region;

[0080] S4, at time t2, the charging current source controls the output voltage v of the voltage control circuit ctrl1 Switch to V p1 , maintain voltage V p1 To time t4;

[0081] S5. At time t4, the charging current source controls the output voltage v of the voltage control circuit. ctrl1 Switch to V p3 , until the driven power device T1 starts to turn off; where V p3 The range of values ​​makes the P-MOS tube M1 used in the charging current source driving circuit work in the variable resistance area;

[0082] S6, at time t5 before the driven power device T1 is turned off, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 is the negative bias voltage V EE ; Among them, the negative bias voltage V EE is the gate-source bias voltage of the driven power device T1 when it is turned off in the steady state;

[0083] S7, at time t5, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 From the negative bias voltage V EE Switch to voltage V n1 , maintain voltage V n1 To time t7;

[0084] S8, at time t7, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 Stepwise decrease to V n2 , and maintain until time t8; where V n1 Greater than V n2 , V n1 and V n2 The range of values ​​makes the N-MOS tube M2 used in the discharge current source driving circuit work in the saturation region;

[0085] S9, at time t8, the discharge current source controls the output voltage v of the voltage control circuitctrl2 Switch to V n1 , maintain voltage V n1 Until t9;

[0086] S10, at time t9, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 Switch to V n3 , and is maintained until the next cycle of the driven power device T1 begins. Among them, V n3 The range of values ​​makes the N-MOS tube M2 used in the discharge current source driving circuit work in the variable resistance area;

[0087] Among them, in S3, the output voltage v ctrl1 Increase and regulate the gate-source voltage v of the P-MOS tube M1 GS1 Increase, so that the drain current of the P-MOS tube M1 decreases, and the drain current change rate di of the driven power device T1 is reduced D / dt to reduce the current stress of the driven power device T1.

[0088] Among them, in S8, the output voltage v ctrl2 Reduce and regulate the gate-source voltage v of the N-MOS tube M2 GS2 The drain current of the N-MOS tube M2 is reduced, thereby reducing the drain current change rate di of the driven power device T1. D / dt to reduce the voltage stress of the driven power device T1.

[0089] A control method for a current source driving circuit includes a control method for a turn-on process of a driven power device T1 and a control method for a turn-off process of the driven power device T1.

[0090] like Figure 6 As shown, Figure 6 The timing diagram of the turn-on transient process of a fast switching dynamic current source drive circuit specifically includes:

[0091] Before t0, the driven power device T1 is in the off steady state, v DS is the bus voltage V BUS , v GS is the negative bias voltage V EE , v ctrl1 is the positive bias voltage V CC So that the P-MOSFET is turned off. At time t0, v ctrl1 From the positive bias voltage V CC Fast switching to voltage V p1 , the P-MOSFET switches from the cut-off region to the saturation region, at which time the gate-source voltage vGS1 Small, driving current i G large, making the gate-source voltage v of the driven power device T1 GS Rapidly rises to the threshold voltage V th , reducing the opening delay.

[0092] At time t1, the drain current i D Rapidly rising, the charging current source controls the output voltage v of the voltage control circuit ctrl1 Gradually increase to V p2 , the P-MOSFET still works in the saturation region, and its gate-source voltage v GS1 Increase, drive current i G Reduce, thereby reducing the drain current change rate di of the driven power device T1 D / dt, thereby reducing the current stress of T1.

[0093] At time t2, the drain-source voltage v of the driven power device T1 is DS The charging current source controls the output voltage v of the voltage control circuit. ctrl1 Switch to V p1 , the P-MOSFET gate-source voltage v GS1 Reduce, drive current i G Increase, speed up v DS The falling process reduces the turn-on loss of T1.

[0094] At time t3, the gate-source voltage v of the driven power device T1 is GS Rapidly rise to positive bias voltage V CC , the charging current source controls the output voltage v of the voltage control circuit ctrl1 Still maintain V p1 , to provide a larger drive current i G , reducing the opening delay.

[0095] At time t4, the transient process of turning on the driven power device T1 ends, and the output voltage v of the voltage control circuit controlled by the charging current source is ctrl1 Switch to V p3 , so that the P-MOSFET works in the variable resistance region, and the gate-source voltage of the driven power device T1 is clamped at the turn-on bias voltage V CC .

[0096] like Figure 7 As shown, Figure 7 The figure is a timing diagram of the turn-off transient process of a fast switching dynamic current source drive circuit, which specifically includes:

[0097] Before time t5, the driven power device T1 is in the on steady state. D is the load current I L , v GS is the positive bias voltage V CC , v ctrl2 is the negative bias voltage V EE So that the N-MOSFET is turned off. At time t5, v ctrl2 From the negative bias voltage V EE Fast switching to voltage V n1 , the N-MOSFET switches from the cut-off region to the saturation region, at which time the gate-source voltage v GS2 Large, driving current i G large, making the gate-source voltage v of the driven power device T1 GS Rapidly decreases to Miller voltage V miller , reducing the shutdown delay.

[0098] At time t6, the drain-source voltage v of the driven power device T1 is DS Rapidly rising, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 Still maintain V n1 , to provide a larger drive current i G , speed up v DS rising process, thereby reducing the turn-off loss of T1.

[0099] At time t7, the drain current i D The discharge current source controls the output voltage v of the voltage control circuit. ctrl2 Switch to V n2 , the N-MOSFET gate-source voltage v GS2 Reduce, drive current i G Reduce, thereby reducing the drain current change rate di of the driven power device T1 D / dt, thereby reducing the voltage stress of T1.

[0100] At time t8, the gate-source voltage v of the driven power device T1 is GS Rapidly drops to negative bias voltage V EE , the discharge current source controls the output voltage v of the voltage control circuit ctrl2 Switch to V n1 , the N-MOSFET gate-source voltage v GS2 Increase, drive current i G Increase, decrease the turn-off delay.

[0101] At time t9, the shutdown transient process of the driven power device T1 ends, and the output voltage v of the voltage control circuit controlled by the discharge current source is ctrl2 Switch to V n3 , so that the N-MOSFET operates in the variable resistance region, and the gate-source voltage of the driven power device T1 is clamped at the turn-off bias voltage V EE .

[0102] like Figure 8 As shown, Figure 8 The schematic diagram is a switching waveform of a drive current output by an inductor-based resonant current source circuit. Specifically, the parasitic inductance of the drive loop is set to 50nH, and the drive current output by the current source circuit is set to switch between 5A and 10A. It takes 363ns for the output current of the resonant current source circuit to switch from 10A to 5A.

[0103] like Fig. 9 As shown, Fig. 9 The schematic diagram is a switching waveform of a mirror current source circuit based on BJT, specifically, the parasitic inductance of the driving loop is set to 50nH, and the driving current output by the current source circuit is set to switch between 5A and 10A. It takes 77ns for the output current of the mirror current source circuit to switch from 10A to 5A, and 130ns for the output current to switch from 5A to 10A.

[0104] like Fig.10 As shown, Fig.10 The schematic diagram of the switching waveform of the output drive current of a fast switching current source circuit proposed in the present invention is shown in FIG. Specifically, the parasitic inductance of the driving loop is set to 50nH, and the output drive current of the current source circuit is set to switch between 5A and 10A. The output current of the proposed current source driving circuit switches from 10A to 5A in 58ns, and switches from 5A to 10A in 79ns.

[0105] As shown in Table 1, Table 1 is a comparison of current switching speeds between a current source driving circuit and the proposed current source driving circuit.

[0106] Table 1

[0107]

[0108]

[0109] Specifically, the driving current switching time of the inductor-based resonant current source is 5.29 times that of the method proposed in the embodiment of the present invention. The driving current switching time of the BJT-based mirror current source is 1.51 times that of the method proposed in the embodiment of the present invention. Therefore, the current source driving circuit proposed in the embodiment of the present invention can achieve a faster driving current switching speed than the current current source driving circuit.

[0110] A control method for a current source drive circuit provided in an embodiment of the present invention controls the output voltage of a charging current source control voltage control circuit and a discharging current source control voltage control circuit to control the gate-source voltage of a MOSFET in the current source drive circuit, thereby achieving dynamic control of the drive current during the switching transient of a power device T1. The control method is simpler, and the drive current control speed of the method is faster, and the method can be applied to wide bandgap power devices with fast switching transients.

[0111] Embodiment 3

[0112] The present invention also provides a double pulse test circuit, comprising: a high voltage DC power supply V1, a DC bus capacitor C1, a load inductor L1, a freewheeling diode D1, a driven power device T1, and a current source drive circuit as described in any one of the first aspects;

[0113] The high-voltage DC power supply V1 and the DC bus capacitor C1 are connected in parallel;

[0114] The load inductor L1 and the freewheeling diode D1 are connected in parallel, and the anode of the freewheeling diode D1 is connected to the drain D of the driven power device T1;

[0115] The source electrode S of the driven power device T1 is connected to the negative electrode of the high voltage DC power supply V1;

[0116] The cathode of the freewheeling diode D1 is connected to the anode of the high voltage DC power supply V1;

[0117] The driven power device T1 is connected to the current source driving circuit, and is turned on or off according to the on / off driving current output by the current source driving circuit.

[0118] like Figure 3 As shown, a double pulse test circuit includes: a high voltage DC power supply V1, a DC bus capacitor C1, a load inductor L1, a freewheeling diode D1, a driven power device T1 and a current source drive circuit. Among them, the source of the P-MOS tube M1 is connected to the positive power supply V CC The drain is connected to the gate G of the driven power device T1, and the gate is connected to the output end of the charging current source control voltage regulation circuit. The source of the N-MOS tube M2 is connected to the negative power supply V EE The drain is connected to the gate G end of the driven power device T1, and the gate is connected to the output end of the discharge current source control voltage regulation circuit.

[0119] Optionally, the driven power device T1 is a three-pin device or a four-pin device;

[0120] When the driven power device T1 is a three-pin device, the Kelvin source KS and the source S are regarded as the same point.

[0121] The driven power device T1 may also be a Si MOS or an IGBT. When the driven power device T1 is a three-pin device, the Kelvin source KS and the source S are regarded as the same point.

[0122] In the double pulse test circuit shown in the figure, the upper tube is always kept off by applying a negative drive voltage, and is used as a freewheeling diode. The lower tube is the SiC MOSFET device to be tested. At the beginning of the test, the control circuit sends the first drive pulse, the lower tube is turned on, the DC bus charges the load inductance, and the load current rises linearly. After a period of time, the first drive pulse ends, the lower tube is turned off, and the load current slowly decays under the action of the stray resistance of the freewheeling loop. After a period of time, the control circuit sends the second drive pulse, the lower tube is turned on again, and the freewheeling diode enters the reverse recovery process. Under the action of the reverse recovery current in the same direction as the load current, the SiC MOSFET drain current overshoots. After a period of time, the second drive pulse ends, the SiC MOSFET drain current decreases rapidly, and the large di / dt formed by the turn-off process acts on the parasitic inductance of the loop, causing a voltage overshoot. Compared with the single pulse test, the double pulse test better simulates the current overshoot phenomenon that may occur in power electronic devices in actual work.

[0123] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A current source driving circuit, wherein the driven power device T1 is a SiC MOS, comprising a gate G, a drain D, a source S and a Kelvin source KS; characterized in that: The current source driving circuit comprises: a charging current source driving circuit, a discharging current source driving circuit, a charging current source control voltage regulating circuit and a discharging current source control voltage regulating circuit; The charging current source driving circuit adopts a P-MOS tube M1, and the source of the P-MOS tube M1 is connected to the positive power supply V CC The drain is connected to the gate G terminal of the driven power device T1, and the gate is connected to the output terminal of the charging current source control voltage regulation circuit; the charging current source driving circuit is used to provide the driving current required for the transient process of turning on the driven power device T1 and the gate-source bias voltage V of T1 when turning on the steady state CC ; The discharge current source driving circuit adopts an N-MOS tube M2, the source of the N-MOS tube M2 is connected to the negative power supply V EE The drain is connected to the gate G terminal of the driven power device T1, and the gate is connected to the output terminal of the discharge current source control voltage regulation circuit; the discharge current source driving circuit is used to provide the driving current required for the transient shutdown process of the driven power device T1 and the gate-source bias voltage V of T1 when the shutdown is steady state EE ; The charging current source controls the output voltage v of the voltage control circuit ctrl1 , used to regulate the gate-source voltage v of the P-MOS tube M1 GS1 , so that when the driven power device T1 is turned on transiently, the P-MOS tube M1 is controlled to work in the saturation region to dynamically adjust the turn-on drive current output by M1; and when the driven power device T1 is turned on steady state, the P-MOS tube M1 is controlled to work in the variable resistance region to clamp the gate-source voltage of the driven power device T1 to the turn-on steady-state bias voltage V CC ; The discharge current source controls the output voltage v of the voltage control circuit ctrl2 , used to regulate the gate-source voltage v of the N-MOS tube M2 GS2 , so that when the driven power device T1 is turned off transiently, the N-MOS tube M2 is controlled to work in the saturation region to dynamically adjust the turn-off drive current output by M2; and when the driven power device T1 is turned off steadily, the N-MOS tube M2 is controlled to work in the variable resistance region to clamp the gate-source voltage of the driven power device T1 to the turn-off steady-state bias voltage V EE .

2. The current source driving circuit according to claim 1, characterized in that: The positive power supply is 15V, and the negative power supply is -5V.

3. The current source driving circuit according to claim 1, characterized in that: The charging current source control voltage regulation circuit includes an FPGA and a first DAC; The digital signal output terminal of the FPGA is connected to the digital signal input terminal of the first DAC, and the analog signal output terminal of the first DAC is connected to the gate of the P-MOS tube M1.

4. The current source driving circuit according to claim 3, characterized in that: The discharge current source control voltage regulation circuit includes the FPGA and a second DAC; The digital signal output terminal of the FPGA is connected to the digital signal input terminal of the second DAC, and the analog signal output terminal of the second DAC is connected to the gate of the N-MOS tube M2.

5. A control method for a current source driving circuit, characterized in that: Based on the circuit according to any one of claims 1 to 4, in one cycle, the driven power device T1 includes a turn-on process and a turn-off process; the control method includes: S1, before the driven power device T1 is in the turn-on process, the charging current source controls the output voltage v of the voltage control circuit ctrl1 is the positive bias voltage V CC ; Among them, the positive bias voltage V CC A gate-source bias voltage for turning on a steady-state for the driven power device T1; S2, at time t0, the charging current source controls the output voltage v of the voltage control circuit ctrl1 From the positive bias voltage V CC Switch to voltage V p1 , maintain voltage V p1 To time t1; S3, at time t1, the charging current source controls the output voltage v of the voltage control circuit ctrl1 Increase to V p2 , and maintain until time t2; where V p1 Less than V p2 , V p1 and V p2 The range of values ​​makes the P-MOS tube M1 used in the charging current source driving circuit work in the saturation region; S4, at time t2, the charging current source controls the output voltage v of the voltage control circuit ctrl1 Switch to V p1 , maintain voltage V p1 To time t4; S5. At time t4, the charging current source controls the output voltage v of the voltage control circuit. ctrl1 Switch to V p3 , until the driven power device T1 starts to turn off; where V p3 The range of values ​​makes the P-MOS tube M1 used in the charging current source driving circuit work in the variable resistance area; S6, at time t5 before the driven power device T1 is turned off, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 is the negative bias voltage V EE ; Among them, the negative bias voltage V EE is the gate-source bias voltage of the driven power device T1 when it is turned off in the steady state; S7, at time t5, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 From the negative bias voltage V EE Switch to voltage V n1 , maintain voltage V n1 To time t7; S8, at time t7, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 Stepwise decrease to V n2 , and maintain until time t8; where V n1 Greater than V n2 , V n1 and V n2 The range of values ​​makes the N-MOS tube M2 used in the discharge current source driving circuit work in the saturation region; S9, at time t8, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 Switch to V n1 , maintain voltage V n1 Until t9; S10, at time t9, the discharge current source controls the output voltage v of the voltage control circuit ctrl2 Switch to V n3 , and is maintained until the next cycle of the driven power device T1 begins. Among them, V n3 The range of values ​​makes the N-MOS tube M2 used in the discharge current source driving circuit work in the variable resistance area.

6. A double pulse test circuit, characterized in that: include: A high-voltage DC power supply V1, a DC bus capacitor C1, a load inductor L1, a freewheeling diode D1, a driven power device T1, and a current source drive circuit as claimed in any one of claims 1 to 4; The high-voltage DC power supply V1 and the DC bus capacitor C1 are connected in parallel; The load inductor L1 and the freewheeling diode D1 are connected in parallel, and the anode of the freewheeling diode D1 is connected to the drain D of the driven power device T1; The source electrode S of the driven power device T1 is connected to the negative electrode of the high voltage DC power supply V1; The cathode of the freewheeling diode D1 is connected to the anode of the high voltage DC power supply V1; The driven power device T1 is connected to the current source driving circuit, and is turned on or off according to the on / off driving current output by the current source driving circuit.

7. The double pulse test circuit as claimed in claim 6, characterized in that: The driven power device T1 is a three-pin device or a four-pin device; When the driven power device T1 is a three-pin device, the Kelvin source KS and the source S are regarded as the same point.

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