CN109462386A - A kind of SiC MOSFET driving circuit applied to hot environment - Google Patents

Abstract

The invention relates to a SiC MOSFET driving circuit applied in a high temperature environment, comprising: a power supply, a main driving circuit, a driving protection circuit and a SiC MOSFET; wherein the power supply is connected to the main driving circuit and the driving protection circuit; the main driving circuit is connected to the SiC MOSFET; The protection circuit connects the main drive circuit and the SiC MOSFET. The invention provides a SiC MOSFET drive circuit applied in a high temperature environment, which solves the contradiction between the switching speed of the triode and the heating of the collector resistance in the level shift circuit; reduces the output drive voltage. The rise time and fall time can also provide a higher frequency drive signal for the SiC MOSFET. The structure of the undervoltage detection circuit is greatly simplified, the reliability of the circuit in a high temperature environment is improved, and the manufacturing cost of the circuit is reduced. A protection delay is set in the overcurrent protection circuit to prevent false triggering of the overcurrent protection circuit.

Description

A SiC MOSFET driver circuit for high temperature environment

technical field

The invention belongs to the technical field of electronic power, and in particular relates to a SiC MOSFET driving circuit applied in a high temperature environment.

Background technique

The driving circuit of the switching device is an important part of the structure of all power converters. It provides enough driving signals for the switching device, and realizes the switching function of the switching device by converting a control signal with a smaller secondary value into a driving signal whose secondary value satisfies the driven switching device.

Traditional silicon-based switching devices generally work in an environment lower than 150°C, and cannot work in an environment higher than 150°C. Compared with silicon-based switching devices, silicon carbide switching devices can operate in a higher temperature environment and have faster switching speeds. Therefore, for the drive circuit to work in a high temperature environment, it must have the characteristics of high temperature resistance and be able to output a high frequency drive signal, which requires that the duration of the rising edge and falling edge of the drive signal be as short as possible. The prior art proposes a design method for a SiC MOSFET drive circuit at high temperature. The proposed drive circuit adopts transformer isolation, and the input signal is distorted after being isolated by the transformer. The distorted input signal is restored, and then the secondary value of the signal is raised to a level capable of driving the SiC MOSFET through the level shift circuit, and finally the driving capability of the circuit is enhanced by the totem pole circuit.

However, the disadvantages of the above-mentioned prior art SiC MOSFET driving circuit for high temperature are: 1) the transmission delay of the circuit is relatively long; 2) the rise time and fall time of the output driving voltage still have room for further reduction.

SUMMARY OF THE INVENTION

In order to solve the above problems existing in the prior art, the present invention provides a SiCMOSFET driving circuit applied in a high temperature environment. The technical problem to be solved by the present invention is realized by the following technical solutions:

An embodiment of the present invention provides a SiC MOSFET driving circuit applied in a high temperature environment, comprising: a power supply, a main driving circuit, a driving protection circuit and a SiC MOSFET; wherein,

the power supply is connected to the main driving circuit and the driving protection circuit, and is used for providing a voltage signal to the main driving circuit and the driving protection circuit;

The main drive circuit is connected to the SiC MOSFET for amplifying and outputting the received control signal;

The driving protection circuit is connected to the main driving circuit and the SiC MOSFET, and is used for detecting the voltage signal of the main driving circuit, and turning on or off the SiC MOSFET according to the detection result.

In an embodiment of the present invention, the main driving circuit includes: a transformer isolation circuit, a driving auxiliary circuit, a level shift circuit, a totem pole circuit, a turn-on resistor and a turn-off resistor; wherein,

the transformer isolation circuit is connected to the level shift circuit;

The drive auxiliary circuit is connected to the transformer isolation circuit, the level shift circuit, the totem pole circuit and the source of the SiC MOSFET;

the level shift circuit is connected to the totem pole circuit;

the totem pole circuit connects the turn-on resistor and the turn-off resistor;

Both the turn-on resistance and the turn-off resistance are connected to the gate of the SiC MOSFET;

The drive protection circuit includes: an undervoltage detection circuit, an overcurrent detection circuit, a protection execution circuit and an overvoltage suppression circuit; wherein,

The power supply includes a first voltage source V1 and the second voltage source V2;

The under-voltage detection circuit is connected to the first voltage source V1, the second voltage source V2 and the protection execution circuit;

The overcurrent detection circuit is connected to the level shift circuit, the second voltage source V2, the protection execution circuit and the drain of the SiC MOSFET;

The protection execution circuit is connected to the first voltage source V1, the level shift circuit and the drive auxiliary circuit;

The overvoltage suppression circuit connects the gate and drain of the SiC MOSFET.

In an embodiment of the present invention, the transformer isolation circuit includes: capacitor C1, capacitor C2, capacitor C3, transformer primary side L1, transformer secondary side L2, diode D1 and resistor R4; wherein,

The capacitor C1 is connected to the upper end of the primary side L1 of the transformer;

The input end of the transformer isolation circuit is connected between the lower end of the primary side L1 of the transformer and the capacitor C1;

The capacitor C2 is connected to the upper end of the secondary side L2 of the transformer, and the capacitor C2 and the diode D1 are connected in series at both ends of the secondary side L2 of the transformer;

The lower end of the transformer secondary side L2 is connected to the ground terminal;

After the capacitor C3 is connected in parallel with the resistor R4, it is connected between the capacitor C2 and the output terminal A of the transformer isolation circuit.

In an embodiment of the present invention, the driving auxiliary circuit includes: a transformer secondary side L3, a resistor R2, a resistor R5, a resistor R6, a transistor Q8 and a transistor Q12; wherein,

The lower end of the transformer secondary side L3 is connected to the lower end of the transformer secondary side L2, the resistor R6, the emitter of the transistor Q12 and the emitter of the transistor Q8 and the first output end B of the drive auxiliary circuit ;

The upper end of the secondary side L3 of the transformer is connected to the resistor R6, the collector of the transistor Q12, the base of the transistor Q8 and the second output end C of the drive auxiliary circuit through the resistor R5;

The input terminal of the auxiliary driving circuit is connected to the source of the SiC MOSFET and the first voltage source V1, and the input terminal of the auxiliary driving circuit is connected to the emitter of the transistor Q8 and the transformer through the resistor R2 for isolation circuit output.

In an embodiment of the present invention, the level shift circuit includes: a transistor Q1, a transistor Q2, a transistor Q6, a transistor Q7, a resistor R1, a resistor R3, a resistor R7 and a resistor R8; wherein,

The base of the triode Q6 is connected to the second output terminal C of the driving auxiliary circuit;

The input end of the level shift circuit is connected to the second voltage source V2, the collector of the transistor Q1 and the emitter of the transistor Q2, and the input end of the level shift circuit is connected through the resistor R2 the base of the triode Q1 and the collector of the triode;

The emitter of the triode Q1 is connected to the base of the triode Q2 through the resistor R3;

The emitter of the transistor Q1 is connected to the first output terminal B of the drive auxiliary circuit through the resistor R7;

The base of the triode Q7 is connected to the output end A of the transformer isolation circuit, and the emitter of the triode Q7 is connected to the first output end B of the drive auxiliary circuit;

The resistor R8 is connected between the first output end B of the drive auxiliary circuit and the output end A of the transformer isolation circuit;

After the collector of the transistor Q7 is connected to the collector of the transistor Q2, it is connected to the output terminal Vg of the level shift circuit.

In an embodiment of the present invention, the totem pole circuit includes: a triode Q3, a triode Q4, a triode Q5, a triode Q9, a triode Q10, and a triode Q11; wherein,

The output terminal Vg of the level shift circuit is connected to the base of the transistor Q3 and the base of the transistor Q9;

The input end of the point shift circuit is connected to the collector of the transistor Q3, the collector of the transistor Q4 and the collector of the transistor Q5;

The emitter of the triode Q3 is connected to the emitter of the triode Q9, the base of the triode Q4, the base of the triode Q5, the base of the triode Q10, and the base of the triode Q11;

The first output terminal B of the driving auxiliary circuit is connected to the collector of the transistor Q9, the collector of the transistor Q10, and the collector of the transistor Q11;

After the emitter of the transistor Q4 is connected to the emitter of the transistor Q5, it is connected to the gate of the SiC MOSFET through the turn-on resistor Ron;

After the emitter of the transistor Q10 is connected to the emitter of the transistor Q11, it is connected to the gate of the SiC MOSFET through the off resistor Roff.

In an embodiment of the present invention, the under-voltage detection circuit includes: a transistor Q15, a transistor Q21, a Zener transistor D3, a Zener transistor D10, a diode D4, a diode D12, a resistor R11, a resistor R16, a resistor R21, and a resistor R25 , resistor R29 and resistor R32; among them,

After the resistor R25 and the resistor R32 are connected in series, they are connected between the base and the emitter of the transistor Q21;

The node where the resistor R25 and the resistor R32 are connected is connected to the first voltage source V1 through a zener tube D10;

The collector of the transistor Q21 is connected to the second voltage source V2 through a resistor R16;

The collector of the transistor Q21 is connected to the output end of the undervoltage detection circuit through a diode D12;

After the emitter of the triode Q21 is connected to the emitter of the triode Q15, it is connected to the ground terminal;

After the resistor R29 is connected in series with the resistor R21, it is connected between the base and the emitter of the transistor Q15;

The node where the resistor R29 and the resistor R21 are connected is connected to the first voltage source V1 through a voltage regulator tube D3;

The collector of the transistor Q15 is connected to the second voltage source V2 through the resistor R11;

The collector of the transistor Q15 is connected to the output terminal of the under-voltage detection circuit through the diode D4.

In an embodiment of the present invention, the overcurrent detection circuit includes: a transistor Q18, a diode D5, a diode D1, a diode D19, a voltage regulator D17, a resistor R12, a resistor R20, a resistor R27 and a capacitor C7; wherein,

After the resistor R27, the capacitor C7 and the voltage regulator D17 are connected in series in sequence, they are connected between the collector and the base of the transistor Q18;

The node where the resistor R27 is connected to the capacitor C7 is connected to the output end Vg of the level shift circuit through a diode D15;

The node where the resistor R27 is connected to the capacitor C7 is connected to the output end of the overcurrent detection circuit through a diode D19;

The node where the capacitor C7 is connected to the voltage regulator tube D17 is connected to the ground terminal;

The resistor R20 is connected between the base and the emitter of the transistor Q18;

The emitter of the transistor Q18 is connected to the second power supply through the resistor R12;

The emitter of the transistor Q18 is connected to the drain of the SiC MOSFET through a diode D5.

In an embodiment of the present invention, the protection execution circuit includes: an initialization subcircuit, a latch subcircuit, a signal execution circuit and a prevention subcircuit; wherein,

The initialization sub-circuit is connected to the first voltage source V1, the latch sub-circuit, the signal execution sub-circuit and the prevention sub-circuit;

The latch subcircuit is connected to the undervoltage detection circuit, the first voltage source V1 and the signal execution subcircuit;

the signal execution subcircuit connects the level shift circuit and the prevention subcircuit;

The prevention subcircuit connects the level shift circuit and the drive auxiliary circuit.

In an embodiment of the present invention, the overvoltage suppression circuit includes: a transistor Q20, a Zener transistor D2, a Zener transistor D11, a diode D14, a diode D16, a diode D18, a diode D20, a resistor R22, a resistor R23, and a resistor R24 , resistor R34 and capacitor C6; among them,

After the diode D18, the capacitor C6, the diode D20 and the resistor R34 are connected in series in sequence, they are connected between the collector and the base of the transistor Q20;

The diode D18 and the node connected to the capacitor C6 are sequentially connected to the emitter of the transistor Q20 through the diode D14 and the resistor R22;

The voltage regulator tube D11 is connected between the emitter and the collector of the triode;

At the node where the capacitor C6 is connected to the diode D20, it is sequentially connected to the gate of the SiC MOSFET through the diode D16 and the resistor R23;

At the node where the diode D20 is connected with the resistor R34, it is connected to the ground terminal;

The resistor R24 is connected between the emitter and the base of the transistor Q20;

The emitter of the transistor Q20 is connected to the drain of the SiC MOSFET through the regulator D2.

Compared with the prior art, the beneficial effects of the present invention:

The SiC MOSFET driving circuit applied in a high temperature environment provided by the invention solves the contradiction between the switching speed of the triode and the heating of the collector resistance in the level shift circuit; greatly reduces the rise time and fall time of the output driving voltage, and can also Provides higher frequency drive signals for SiC MOSFETs. The structure of the undervoltage detection circuit is greatly simplified, the reliability of the circuit in a high temperature environment is improved, and the manufacturing cost of the circuit is reduced. A protection delay is set in the overcurrent protection circuit to prevent false triggering of the overcurrent protection circuit.

Description of drawings

1 is a schematic structural diagram of a SiC MOSFET driving circuit applied in a high temperature environment provided by the present invention;

2 is a schematic diagram of a main drive circuit provided by the present invention;

3 is a schematic diagram of an undervoltage detection circuit provided by the present invention;

FIG. 4 is a schematic diagram of an overcurrent detection circuit provided by the present invention.

Detailed ways

The present invention will be described in further detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

Example 1

Please refer to FIG. 1 to FIG. 4. FIG. 1 is a schematic structural diagram of a SiC MOSFET driving circuit applied in a high temperature environment provided by the present invention; FIG. 2 is a schematic diagram of a main driving circuit provided by the present invention; A schematic diagram of a voltage detection circuit; FIG. 4 is a schematic diagram of an overcurrent detection circuit provided by the present invention.

As shown in Figure 1, a SiC MOSFET driving circuit applied in a high temperature environment includes: a power supply, a main driving circuit, a driving protection circuit and a SiC MOSFET; wherein,

The power supply is connected to the main drive circuit and the drive protection circuit, and is used to provide voltage signals to the main drive circuit and the drive protection circuit;

The main drive circuit is connected to the SiC MOSFET for amplifying and outputting the received control signal, specifically for amplifying the secondary value of the control signal input to the main driving circuit, and outputting the drive signal with steep rising and falling edges;

The drive protection circuit is respectively connected to the main drive circuit and the SiC MOSFET, and is used to detect the voltage signal of the main drive circuit and turn on or off the SiC MOSFET according to the detection result.

Further, the main driving circuit includes: a transformer isolation circuit, a driving auxiliary circuit, a level shift circuit, a totem pole circuit, an on-resistance Ron and an off-resistance Roff; wherein,

The transformer isolation circuit is connected to the level shift circuit for electrical isolation;

The drive auxiliary circuit is respectively connected to the transformer isolation circuit, the level shift circuit, the totem pole circuit and the source of the SiCMOSFET, and is used for the output of the auxiliary transformer isolation circuit;

The level shift circuit is connected to the totem pole circuit for

The totem pole circuit is respectively connected to the turn-on resistance and the turn-off resistance; it is used to enhance the driving signal;

The turn-on and turn-off resistors are connected to the gates of the SiC MOSFETs, respectively;

The drive protection circuit includes: an undervoltage detection circuit, an overcurrent detection circuit, a protection execution circuit and an overvoltage suppression circuit; wherein,

The power supply includes a first voltage source V1 and a second voltage source V2,

The under-voltage detection circuit is respectively connected to the first voltage source V1, the second voltage source V2 and the protection execution circuit;

The overcurrent detection circuit is respectively connected to the level shift circuit, the second voltage source V2, the protection execution circuit and the drain of the SiCMOSFET;

The protection execution circuit is respectively connected to the first voltage source V1, the level shift circuit and the driving auxiliary circuit;

Overvoltage suppression circuits are connected to the gate and drain of the SiC MOSFET, respectively.

Further, as shown in FIG. 2, the transformer isolation circuit includes: capacitor C1, capacitor C2, capacitor C3, transformer primary side L1, transformer secondary side L2, diode D1 and resistor R4; wherein,

The capacitor C1 is connected to the upper end of the primary side L1 of the transformer;

The input end of the transformer isolation circuit is connected between the lower end of the primary side L1 of the transformer and the capacitor C1; the control signal is input to the main drive circuit through the input end of the transformer isolation circuit;

The capacitor C2 is connected to the upper end of the secondary side L2 of the transformer, and the capacitor C2 and the diode D1 are connected in series with both ends of the secondary side L2 of the transformer;

The lower end of the transformer secondary side L2 is connected to the ground terminal;

After the capacitor C3 is connected in parallel with the resistor R4, it is connected between the capacitor C2 and the output terminal A of the transformer isolation circuit.

Specifically, the function of the capacitor C1 is to filter out the DC component in the input control signal, and the function of the capacitor C2 and the diode D1 is to make up the filtered DC component.

Further, the drive auxiliary circuit includes: transformer secondary side L3, resistor R2, resistor R5, resistor R6, transistor Q8 and transistor Q12; wherein,

The lower end of the transformer secondary side L3 is respectively connected to the lower end of the transformer secondary side L2, the resistor R6, the emitter of the triode Q12, the emitter of the triode Q8 and the first output end B of the drive auxiliary circuit;

The upper end of the secondary side L3 of the transformer is respectively connected to the resistor R6, the collector of the transistor Q12, the base of the transistor Q8 and the second output terminal C of the drive auxiliary circuit through the resistor R5;

The input terminal of the driving auxiliary circuit is respectively connected to the source of the SiC MOSFET and the first voltage source V1, and the input terminal of the driving auxiliary circuit is respectively connected to the emitter of the transistor Q8 and the output terminal of the transformer isolation circuit through the resistor R2.

Specifically, the drive auxiliary circuit is used to prevent the SiC MOSFET from being turned on when no control signal is input. Also used to assist transistor Q7 to turn on and off.

Further, the level shift circuit includes: transistor Q1, transistor Q2, transistor Q6, transistor Q7, resistor R1, resistor R3, resistor R7 and resistor R8; wherein,

The base of the triode Q6 is connected to the second output terminal C of the driving auxiliary circuit;

The input terminal of the level shift circuit is respectively connected to the second voltage source V2, the collector of the transistor Q1 and the emitter of the transistor Q2, and the input terminal of the level shift circuit is respectively connected to the base of the transistor Q1 and the collector of the transistor Q1 through the resistor R2 ;

The emitter of the transistor Q1 is connected to the base of the transistor Q2 through the resistor R3;

The emitter of the transistor Q1 is connected to the first output terminal B of the driving auxiliary circuit through the resistor R7;

The base of the triode Q7 is connected to the output end A of the transformer isolation circuit, and the emitter of the triode Q7 is connected to the first output end B of the driving auxiliary circuit;

The resistor R8 is connected between the first output end B of the drive auxiliary circuit and the output end A of the transformer isolation circuit;

After the collector of the transistor Q7 is connected to the collector of the transistor Q2, it is connected to the output terminal Vg of the level shift circuit.

Specifically, the working principle of the drive auxiliary circuit is as follows: when there is no input, the primary side L1, secondary side L2 and secondary side L3 of the transformer have no voltage, the transistor Q8 is turned off, and the first power supply V1 provides the base for the transistor Q7 through the resistor R2. The current turns on the transistor Q7 and pulls down the output terminal Vg of the level shift circuit, so as to realize that no driving signal is output when there is no input control signal. At the same time, the driving auxiliary circuit has an auxiliary effect on the switching process of the transistor Q7 when there is an input control signal. That is, when the transistor Q7 is turned on, the first voltage source V1 and the resistor R2 assist the secondary side L2 and the capacitor C2 so that the transistor Q7 can be turned on quickly; when the transistor Q7 is turned off, the transistor Q8 is turned on, providing a fast discharge circuit for the transistor Q7. , so that the transistor Q7 is turned off quickly.

Specifically, the working principle of the level shift circuit is: when the transistor Q7 is turned on, the transistor Q6 is turned off, the second voltage source V2 provides the base current for the transistor Q1 through the resistor R1, the transistor Q1 is turned on, and the emitter voltage of the transistor Q1 It is raised to the second voltage source V2. At this time, the emitter junction voltage of the transistor Q2 is 0, then the transistor Q2 is turned off, and the output terminal Vg of the level shift circuit is pulled down; in the process of turning off the transistor Q7, the transistor Q6 is turned on, The base voltage of the transistor Q1 is pulled down to the ground potential, then the transistor Q1 is turned off, the second voltage source V2 provides the base current of Q2 through the resistor R3, the resistor R7 and the emitter junction of the transistor Q2, then the transistor Q2 is turned on, and the level shifts The output terminal Vg of the bit circuit is pulled high.

Further, the totem pole circuit includes: a triode Q3, a triode Q4, a triode Q5, a triode Q9, a triode Q10 and a triode Q11; wherein,

The output terminal Vg of the level shift circuit is respectively connected to the base of the transistor Q3 and the base of the transistor Q9;

The input end of the point shift circuit is respectively connected to the collector of the transistor Q3, the collector of the transistor Q4 and the collector of the transistor Q5;

The emitter of the transistor Q3 is respectively connected to the emitter of the transistor Q9, the base of the transistor Q4, the base of the transistor Q5, the base of the transistor Q10, and the base of the transistor Q11;

The first output terminal B of the driving auxiliary circuit is respectively connected to the collector of the transistor Q9, the collector of the transistor Q10, and the collector of the transistor Q11.

After the emitter of the transistor Q4 is connected to the emitter of the transistor Q5, it is connected to the gate of the SiCMOSFET by turning on the resistor Ron;

After the emitter of the transistor Q10 is connected to the emitter of the transistor Q11, it is connected to the gate of the SiCMOSFET through the off resistor Roff.

Specifically, the working principle of the totem pole circuit is: when the output terminal Vg of the level shift circuit is high, the transistor Q3 is turned on, the second voltage source V2 provides the base current for the transistor Q4 and the transistor Q5 through the transistor Q3, and the transistor Q3 Q4 and transistor Q5 are turned on, and the gate potential of the SiC MOSFET is pulled up to the second voltage source V2; when the output terminal Vg of the level shift circuit is low, the transistor Q9, the transistor Q10 and the transistor Q11 are turned on, and the gate of the SiC MOSFET is turned on. The pole potential is pulled down to the ground potential; the output voltage high level is the difference V1 of the second voltage source V2 minus the first voltage source, and the output low level is the negative first voltage source.

Specifically, the totem pole circuit is used to enhance the driving capability of the main driving circuit. Preferably, the number of parallel groups of totem pole circuits can be adjusted according to specific needs.

Further, as shown in FIG. 3 , the under-voltage detection circuit includes: transistor Q15, transistor Q21, Zener transistor D3, Zener transistor D10, diode D4, diode D12, resistor R11, resistor R16, resistor R21, resistor R25, resistor R29 and resistor R32; where,

After the resistor R25 and the resistor R32 are connected in series, they are connected between the base and the emitter of the transistor Q21;

The node where the resistor R25 and the resistor R32 are connected is connected to the first voltage source V1 through the zener tube D10;

The collector of the transistor Q21 is connected to the second voltage source V2 through the resistor R16;

The collector of the transistor Q21 is connected to the output terminal of the under-voltage detection circuit through the diode D12;

After the emitter of the transistor Q21 is connected to the emitter of the transistor Q15, it is connected to the ground terminal;

After the resistor R29 is connected in series with the resistor R21, it is connected between the base and the emitter of the transistor Q15;

The node where the resistor R29 and the resistor R21 are connected is connected to the first voltage source V1 through the zener tube D3;

The collector of the transistor Q15 is connected to the second voltage source V2 through the resistor R11;

The collector of the transistor Q15 is connected to the output terminal of the under-voltage detection circuit through the diode D4.

Specifically, the cathode of the diode D10 is connected to the first voltage source V1, the anode of the diode D10 is connected to the resistor R32 and the resistor R25, the other end of the resistor R25 is connected to the base of the transistor Q21, the emitter of the transistor Q21 is grounded, and the collector of the transistor Q21 Connect the anode of diode D12 and resistor R16. The other end of the resistor R16 is connected to the second voltage source V2, the cathode of the diode D3 is connected to the second voltage source V2, the anode is connected to the resistor R29 and the resistor R21, the other end of the resistor R21 is connected to the base of the transistor Q15, the emitter of the transistor Q15 The electrode is grounded, the collector of the transistor Q15 is connected to the anode of the diode D4 and the resistor R11, and the other end of the resistor R11 is connected to the second voltage source V2. The cathode of the diode D4 is connected to the cathode of the diode D12 and is connected to the output end of the under-voltage detection circuit, the output end is Fault1, and the output end is connected to the protection execution circuit. The collector of Q22 in the circuit.

Specifically, the transistor Q15 and the transistor Q21 are both PNP type BJTs.

Specifically, when the first voltage source V1 is under-voltage, that is, when V1 is lower than the reference voltage value, the transistor Q21 is turned off, and Fault1 is pulled high; when the second voltage source V2 is under-voltage, that is, the second voltage source V2 is lower than the reference voltage value. When the voltage value is reached, the transistor Q15 is turned off, and Fault1 is pulled high. The function of diode D4 and diode D12 is to prevent mutual interference between the under-voltage detection circuit and the protection execution circuit.

Further, as shown in FIG. 4 , the overcurrent detection circuit includes: a transistor Q18, a diode D5, a diode D1, a diode D19, a voltage regulator D17, a resistor R12, a resistor R20, a resistor R27 and a capacitor C7; wherein,

After the resistor R27, the capacitor C7 and the voltage regulator tube D17 are connected in series in sequence, they are connected between the collector and the base of the transistor Q18;

The node where the resistor R27 is connected to the capacitor C7 is connected to the output terminal Vg of the level shift circuit through the diode D15;

The node where the resistor R27 is connected to the capacitor C7 is connected to the output end of the overcurrent detection circuit through the diode D19;

The node where the capacitor C7 is connected to the voltage regulator tube D17 is connected to the ground terminal;

The resistor R20 is connected between the base and the emitter of the transistor Q18;

The emitter of the transistor Q18 is connected to the second power supply through the resistor R12;

The emitter of transistor Q18 is connected to the drain of the SiC MOSFET through diode D5.

Specifically, the second voltage source V2 is connected to the anode of the diode D5, the emitter of the transistor Q18 and the resistor R20 through the resistor R2, the cathode of the diode D5 is connected to the drain of the SiC MOSFET, the resistor R20 is connected in parallel to the emitter junction of the transistor Q18, and the voltage regulator The cathode of the tube D17 is connected to the base of the transistor Q18, its anode is connected to the capacitor C7 and grounded, the collector of the transistor Q18 is connected to the resistor R27, the resistor R27 is connected to the capacitor C7, and is connected to the anode of the diode D15 and the diode D19. The diode D15 The cathode of the diode D19 is connected to the output terminal Vg of the level shift circuit, that is, connected to the collector of Q7 in the main drive circuit, and the cathode of the diode D19 is connected to the output terminal of the overcurrent detection circuit, denoted as Fault2.

Specifically, the overcurrent detection circuit is powered by the second voltage source V2, and when the output terminal Vg of the level shift circuit is 0, the Fault2 is clamped to 0 potential. That is to say, no overcurrent detection is performed when the SiC MOSFET is turned off. When the output terminal Vg of the level shift circuit is at a high level, the diode D15 is turned off, and the output terminal Vg of the level shift circuit loses its clamping effect on Fault2. Overcurrent detection is only performed when the SiC MOSFET is on. At this time, if no overcurrent occurs, the anode potential of the diode D5 is clamped to about 2V by the drain voltage, and the voltage regulator D17 cannot be turned on, then the transistor Q18 has no base current, and the transistor Q18 is turned off; When the capacitor C7 is charged, Fault2 is invalid; if an overcurrent fault occurs at this time, and when the drain voltage V _D of the SiC MOSFET is higher than the reference voltage value, the voltage regulator D17 is turned on, generating a path for the base current of the transistor Q18, the transistor Q18 is turned on and capacitor C7 starts to charge. When the voltage across capacitor C7 rises to 1.4V, Fault2 rises to 0.7V and is latched by the protection logic circuit.

Specifically, the error reporting delay is set by C7, and different error reporting delay times can be set by adjusting the values of the capacitor C7 and the resistor R27. Since the drain current is only detected when the SiC MOSFET is turned on, this function is implemented by diode D15.

Further, the protection execution circuit includes: an initialization subcircuit, a latch subcircuit, a signal execution circuit and a prevention subcircuit; wherein,

The initialization sub-circuit is connected to the first voltage source V1, the latch sub-circuit, the signal execution sub-circuit and the prevention sub-circuit;

The latch subcircuit is connected to the undervoltage detection circuit, the first voltage source V1 and the signal execution subcircuit;

The signal execution subcircuit is connected to the level shift circuit and the prevention subcircuit;

The prevention subcircuit connects the level shift circuit and the drive auxiliary circuit.

Specifically, the initialization sub-circuit includes: a capacitor C5, a resistor R33, a resistor R26, a transistor Q16, and a transistor Q22. One end of the capacitor C5 is connected to the first voltage source V1, the other end is connected to the resistor R26 and the resistor R33, and the other end of the resistor R26 is connected to the first voltage source V1. One end is connected to the bases of the transistor Q16 and the transistor Q22, the emitters of the transistor Q16 and the transistor Q22 are grounded, and the collector of the transistor Q16 is connected to Fault2 and the collector of the transistor Q22 is connected to Fault1.

The latch sub-circuit includes: transistor Q14, transistor Q17, resistor R10, resistor R13, resistor R18, and resistor R14, wherein the emitters of transistor Q14 and transistor Q17 are both grounded, and between the collector of transistor Q14 and the base of transistor Q17 Indirect resistor R13, a resistor R18 is connected between the base of the transistor Q14 and the collector of the transistor Q17, a resistor R10 and a resistor R14 are respectively connected to the collectors of the transistor Q14 and the transistor Q17, and the other ends of the resistor R10 and the resistor R14 are connected to the third A voltage source V1.

The signal execution sub-circuit includes: diode D6, diode D13, resistor R30, transistor Q19, and resistor R19, wherein the anode of diode D6 is connected to the collector of transistor Q17, the anode of diode D13 is connected to the collector of transistor Q22, diode D6 and diode D13 The cathode is connected to the resistor R30, the base of the transistor Q19, and is connected to the prevention subcircuit. The other end of the resistor R30 is connected to the emitter of the transistor Q19 and grounded, one end of the resistor R19 is connected to the collector of the transistor Q19, and the other end of the resistor R19 is connected to the collector of the transistor Q7 in the main driving circuit.

The prevention sub-circuit includes: resistor R15, transistor Q13, resistor R31, diode D7, diode D8, resistor R17, diode D9, and resistor R28, wherein the cathode of diode D7 is connected to the cathode of diode D6, and the emitter of transistor Q13 is in phase with resistor R17. Connected and connected to the first voltage source V1, one end of the resistor R15 is connected to the base of the transistor Q13, the other end is connected to the collector of the transistor Q7 in the main drive circuit, and the other end of the resistor R17 is connected to the anode of the diode D7, diode D8 and diode D9. The cathode of the diode D8 is connected to the collector of the transistor Q13 and one end of the resistor R31, and the other end of the resistor R31 is connected to the ground. The cathode of the diode D9 is connected to the resistor R28 and the base of the transistor Q9 in the main drive circuit and one end of the resistor R28, and the other end of the resistor R28 is grounded.

Specifically, the protection execution circuit is used to clear Fault1 and Fault2 at the moment when the main drive circuit is powered on. Among them, the function of the latch sub-circuit is to latch the Fault2 signal once the overcurrent signal is generated, so that the Fault2 is always valid, and the Fault2 cannot be cleared until the power is turned off and restarted. The function of the signal execution sub-circuit is to turn on the transistor Q19 regardless of the occurrence of an undervoltage fault or an overcurrent fault, and the voltage of the output terminal Vg of the level shift circuit is pulled down to the voltage of the first voltage source V1, and then the transistor Q7 in the main drive circuit is turned on. Turning on, the voltage of the output terminal Vg of the level shift circuit is pulled down to 0, and the two-step turn-off is realized. The prevention subcircuit is used to prevent VGS from tripping after a two-step MOSFET turn-off after a fault. The prevention subcircuit is used to prevent the gate-source voltage _VGS of the SiC MOSFET from jumping after the two-step turn-off of the faulty MOSFET.

Specifically, the overvoltage suppression circuit includes: a transistor Q20, a Zener transistor D2, a Zener transistor D11, a diode D14, a diode D16, a diode D18, a diode D20, a resistor R22, a resistor R23, a resistor R24, a resistor R34 and a capacitor C6; wherein ,

After the diode D18, the capacitor C6, the diode D20 and the resistor R34 are connected in series in sequence, they are connected between the collector and the base of the transistor Q20;

At the node where the diode D18 and the capacitor C6 are connected, the diode D14 and the resistor R22 are sequentially connected to the emitter of the transistor Q20;

Zener tube D11 is connected between the emitter and collector of the triode;

At the node where the capacitor C6 is connected to the diode D20, it is sequentially connected to the gate of the SiCMOSFET through the diode D16 and the resistor R23;

At the node where diode D20 is connected to resistor R34, it is connected to ground

The resistor R24 is connected between the emitter and the base of the transistor Q20;

The emitter of the transistor Q20 is connected to the drain of the SiC MOSFET through the regulator D2.

Specifically, the cathode of the diode D2 is connected to the drain of the SiC MOSFET, its anode is connected to the transistor Q20 and the resistor R24, the resistor R24 is connected in parallel between the emitter and the base of the transistor Q20, and the base of the transistor Q20 is connected to the resistor R34. One end is connected, and the other end of the resistor R34 is connected to the anode of the diode D20 and grounded. The diode D11 is connected in parallel between the collector and the emitter of the transistor Q20 to prevent the transistor Q20 from being broken down. The collector of the transistor Q20 is connected to the anode of the diode D18, and the cathode of the diode D18 is connected to the anode of the diode D14 and the capacitor C6, respectively. One end of the resistor R22 is connected to the cathode of the diode D14, and the other end of the resistor R22 is connected to the collector of the transistor Q20. The other end of the capacitor C6 is connected to the anode of the diode D16 and the cathode of the diode D20, respectively. One end of the resistor R23 is connected to the cathode of the diode D16, and the other end is connected to the gate of the SiC MOSFET.

Preferably, for the purpose of realizing the overvoltage suppression function, a peak current is injected into the gate of the SiC MOSFET during the turn-off process to slow down the turn-off process and reduce the rate of change of the drain current. As a result, the stray inductance on the line in the circuit or the induced voltage on the leakage inductance of the transformer can be reduced, thereby reducing the voltage stress on the SiC MOSFET during the turn-off process.

Specifically, a reference voltage is set through the diode D2. When the SiC MOSFET is turned off, the drain voltage V _D of the SiC MOSFET rises, and when it exceeds the reference voltage value, the diode D2 is turned on, the transistor Q20 is turned on, and the instantaneous voltage will be This causes capacitor C6 to generate a spike current, which is injected into the gate of the SiC MOSFET through diode D16 and resistor R23. Diode D20, diode D14, resistor R22, and diode D2 form the discharge circuit of capacitor C6. After that, the SiC MOSFET is turned off stably, and VD begins to decrease, gradually approaching the bus voltage value of the SiC MOSFET. Because the voltage regulation value of D2 is slightly lower than the bus voltage value, D2 is still conducting, but the rate of change of VD is close to 0, and the current value through capacitor C6 is close to 0. Then no current is injected into the gate of the SiC MOSFET, which will not affect the normal turn-off of the SiC MOSFET. When the MOSFET is turned on, VD drops to about 1V, the diode D2 is turned off, and the circuit has no effect on the driving circuit.

The working process of the main drive circuit provided in this embodiment is as follows: when the control signal Vin input to the main drive circuit is at a high level, the primary side L1 of the transformer is positive and negative at the bottom, and the secondary side L2 of the transformer is negative at the top and positive at the bottom, and the capacitor C2 is supplied to the capacitor C2 through the diode D1. Charging; the upper and lower sides of the secondary side L3 of the transformer are positive and lower, the transistor Q8 and the transistor Q6 are turned on, and the transistor Q8 is turned on to provide a low-impedance discharge circuit for the transistor Q7; the conduction of the transistor Q6 makes the transistor Q1 turn off and the transistor Q2 is turned on; thus making The second voltage source V2 pulls up the output terminal Vg of the level shift circuit through the transistor Q2.

When the control signal Vin input to the main drive circuit is at a low level, the primary side L1 of the transformer is negative on the upper side, and the secondary side L2 is positive on the lower side. The pole current turns on the transistor Q7; the upper and lower sides of the secondary side L3 of the transformer are negative, the transistor Q8 and the transistor Q6 are off, and the transistor Q8 is off to create conditions for the conduction of the transistor Q7; the transistor Q6 is off. The transistor Q1 is turned on, and the transistor Q2 is off; The output terminal Vg of the level shift circuit is pulled down by the transistor Q7, so that no current flows through the transistor Q7 when the transistor Q7 is turned on. This can not only remove the collector resistance of the transistor Q7 and solve the problem of heating of the collector resistance, but also reduce the power consumption of the transistor Q7 and improve the switching speed of the transistor Q7. After that, the output terminal Vg of the level shift circuit is output to the SiC MOSFET through the totem pole circuit to enhance the driving capability.

The SiC MOSFET driving circuit applied in a high temperature environment provided by the invention solves the contradiction between the switching speed of the triode and the heating of the collector resistance in the level shift circuit; greatly reduces the rise time and fall time of the output driving voltage, and can also Provides higher frequency drive signals for SiC MOSFETs. The structure of the undervoltage detection circuit is greatly simplified, the reliability of the circuit in a high temperature environment is improved, and the manufacturing cost of the circuit is reduced. A protection delay is set in the overcurrent protection circuit to prevent false triggering of the overcurrent protection circuit.

The performance of the embodiments of the present invention will be further described below in conjunction with simulation experiments.

1. Simulation conditions:

The invention adopts Pspice software to simulate the circuit. A square wave signal with a secondary value of 5V, a frequency of 100KHZ, and a duty cycle of 50% is used as the input control signal of the drive circuit, Ron and Roff are both 2Ω, and a capacitor with a capacitance value of 2nF is used to simulate the gate source of the SiC MOSFET of the SiC MOSFET voltage C _GS .

2. Simulation content:

Mainly observe and measure the rise time, fall time, rising edge delay and falling edge delay of the output voltage of the main drive circuit. As well as the functional verification of the undervoltage protection circuit, the functional verification of the overcurrent protection circuit, the functional verification of the protection execution circuit, and the observation of whether the source-drain voltage _VDS of the SiC MOSFET changes before and after the overvoltage suppression circuit is added to the circuit.

3. Analysis of simulation results:

1) The rise time of the output voltage of the main drive circuit is 14.536ns, and the fall time is 30.385ns. The rise time and fall time are greatly reduced compared with the same type of driving circuit.

2) The undervoltage detection circuit is consistent with the theoretical analysis results, and the undervoltage detection function is realized;

3) The voltage waveform of each point in the overcurrent detection circuit is consistent with the theoretical analysis results, and the overcurrent fault signal can be correctly generated;

4) The fault signal generated by the simulation is transmitted to the protection execution circuit, and the protection execution circuit can pull down Vg after receiving the fault signal to realize two-step shutdown.

5) The function of the overvoltage suppression circuit has also been verified. Without the suppression circuit (the bus voltage of the power circuit is 600V), the peak voltage value is 890V; after the overvoltage suppression circuit is added, the source-drain voltage of the SiC MOSFET The peak voltage value of V _DS is 644.5V. The inhibitory effect is obvious.

The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be considered that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deductions or substitutions can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (10)

1. a SiC MOSFET drive circuit applied to high temperature environment, is characterized in that, comprises: power supply, main drive circuit, drive protection circuit and SiC MOSFET; Wherein, the power supply is connected to the main driving circuit and the driving protection circuit, and is used for providing a voltage signal to the main driving circuit and the driving protection circuit; The main drive circuit is connected to the SiC MOSFET for amplifying and outputting the received control signal; The driving protection circuit is connected to the main driving circuit and the SiC MOSFET, and is used for detecting the voltage signal of the main driving circuit, and turning on or off the SiC MOSFET according to the detection result. 2. The SiC MOSFET drive circuit according to claim 1, wherein the main drive circuit comprises: a transformer isolation circuit, a drive auxiliary circuit, a level shift circuit, a totem pole circuit, an on-resistance and an off-resistance; wherein , the transformer isolation circuit is connected to the level shift circuit; The drive auxiliary circuit is connected to the transformer isolation circuit, the level shift circuit, the totem pole circuit and the source of the SiC MOSFET; the level shift circuit is connected to the totem pole circuit; the totem pole circuit connects the turn-on resistor and the turn-off resistor; Both the turn-on resistance and the turn-off resistance are connected to the gate of the SiC MOSFET; The drive protection circuit includes: an undervoltage detection circuit, an overcurrent detection circuit, a protection execution circuit and an overvoltage suppression circuit; wherein, The power supply includes a first voltage source V1 and the second voltage source V2; The under-voltage detection circuit is connected to the first voltage source V1, the second voltage source V2 and the protection execution circuit; The overcurrent detection circuit is connected to the level shift circuit, the second voltage source V2, the protection execution circuit and the drain of the SiC MOSFET; The protection execution circuit is connected to the first voltage source V1, the level shift circuit and the drive auxiliary circuit; The overvoltage suppression circuit connects the gate and drain of the SiC MOSFET. 3. SiC MOSFET drive circuit according to claim 2, is characterized in that, described transformer isolation circuit comprises: capacitor C1, capacitor C2, capacitor C3, transformer primary side L1, transformer secondary side L2, diode D1 and resistor R4; in, The capacitor C1 is connected to the upper end of the primary side L1 of the transformer; The input end of the transformer isolation circuit is connected between the lower end of the primary side L1 of the transformer and the capacitor C1; The capacitor C2 is connected to the upper end of the secondary side L2 of the transformer, and the capacitor C2 and the diode D1 are connected in series at both ends of the secondary side L2 of the transformer; The lower end of the transformer secondary side L2 is connected to the ground terminal; After the capacitor C3 is connected in parallel with the resistor R4, it is connected between the capacitor C2 and the output terminal A of the transformer isolation circuit. 4. The SiC MOSFET drive circuit according to claim 3, wherein the drive auxiliary circuit comprises: a transformer secondary side L3, a resistor R2, a resistor R5, a resistor R6, a transistor Q8 and a transistor Q12; wherein, The lower end of the transformer secondary side L3 is connected to the lower end of the transformer secondary side L2, the resistor R6, the emitter of the transistor Q12 and the emitter of the transistor Q8 and the first output end B of the drive auxiliary circuit ; The upper end of the secondary side L3 of the transformer is connected to the resistor R6, the collector of the transistor Q12, the base of the transistor Q8 and the second output end C of the drive auxiliary circuit through the resistor R5; The input terminal of the auxiliary driving circuit is connected to the source of the SiC MOSFET and the first voltage source V1, and the input terminal of the auxiliary driving circuit is connected to the emitter of the transistor Q8 and the transformer through the resistor R2 for isolation circuit output. 5. SiC MOSFET drive circuit according to claim 4, is characterized in that, described level shift circuit comprises: transistor Q1, transistor Q2, transistor Q6, transistor Q7, resistance R1, resistance R3, resistance R7 and resistance R8; in, The base of the triode Q6 is connected to the second output terminal C of the driving auxiliary circuit; The input end of the level shift circuit is connected to the second voltage source V2, the collector of the transistor Q1 and the emitter of the transistor Q2, and the input end of the level shift circuit is connected through the resistor R2 the base of the triode Q1 and the collector of the triode; The emitter of the triode Q1 is connected to the base of the triode Q2 through the resistor R3; The emitter of the transistor Q1 is connected to the first output terminal B of the drive auxiliary circuit through the resistor R7; The base of the triode Q7 is connected to the output end A of the transformer isolation circuit, and the emitter of the triode Q7 is connected to the first output end B of the drive auxiliary circuit; The resistor R8 is connected between the first output end B of the drive auxiliary circuit and the output end A of the transformer isolation circuit; After the collector of the transistor Q7 is connected to the collector of the transistor Q2, it is connected to the output terminal Vg of the level shift circuit. 6. The SiC MOSFET drive circuit according to claim 5, wherein the totem pole circuit comprises: a transistor Q3, a transistor Q4, a transistor Q5, a transistor Q9, a transistor Q10 and a transistor Q11; wherein, The output terminal Vg of the level shift circuit is connected to the base of the transistor Q3 and the base of the transistor Q9; The input end of the point shift circuit is connected to the collector of the transistor Q3, the collector of the transistor Q4 and the collector of the transistor Q5; The emitter of the triode Q3 is connected to the emitter of the triode Q9, the base of the triode Q4, the base of the triode Q5, the base of the triode Q10, and the base of the triode Q11; The first output terminal B of the driving auxiliary circuit is connected to the collector of the transistor Q9, the collector of the transistor Q10, and the collector of the transistor Q11; After the emitter of the transistor Q4 is connected to the emitter of the transistor Q5, it is connected to the gate of the SiC MOSFET through the turn-on resistor Ron; After the emitter of the transistor Q10 is connected to the emitter of the transistor Q11, it is connected to the gate of the SiC MOSFET through the off resistor Roff. 7. The SiC MOSFET drive circuit according to claim 5, wherein the undervoltage detection circuit comprises: a transistor Q15, a transistor Q21, a Zener transistor D3, a Zener transistor D10, a diode D4, a diode D12, and a resistor R11 , resistor R16, resistor R21, resistor R25, resistor R29 and resistor R32; among them, After the resistor R25 and the resistor R32 are connected in series, they are connected between the base and the emitter of the transistor Q21; The node where the resistor R25 and the resistor R32 are connected is connected to the first voltage source V1 through a zener tube D10; The collector of the transistor Q21 is connected to the second voltage source V2 through a resistor R16; The collector of the transistor Q21 is connected to the output end of the undervoltage detection circuit through a diode D12; After the emitter of the triode Q21 is connected to the emitter of the triode Q15, it is connected to the ground terminal; After the resistor R29 is connected in series with the resistor R21, it is connected between the base and the emitter of the transistor Q15; The node where the resistor R29 and the resistor R21 are connected is connected to the first voltage source V1 through a voltage regulator tube D3; The collector of the transistor Q15 is connected to the second voltage source V2 through the resistor R11; The collector of the transistor Q15 is connected to the output terminal of the under-voltage detection circuit through the diode D4. 8. The SiC MOSFET drive circuit according to claim 1, wherein the overcurrent detection circuit comprises: a transistor Q18, a diode D5, a diode D1, a diode D19, a voltage regulator D17, a resistor R12, a resistor R20, a resistor R27 and capacitor C7; where, After the resistor R27, the capacitor C7 and the voltage regulator D17 are connected in series in sequence, they are connected between the collector and the base of the transistor Q18; The node where the resistor R27 is connected to the capacitor C7 is connected to the output end Vg of the level shift circuit through a diode D15; The node where the resistor R27 is connected to the capacitor C7 is connected to the output end of the overcurrent detection circuit through a diode D19; The node where the capacitor C7 is connected to the voltage regulator tube D17 is connected to the ground terminal; The resistor R20 is connected between the base and the emitter of the transistor Q18; The emitter of the transistor Q18 is connected to the second power supply through the resistor R12; The emitter of the transistor Q18 is connected to the drain of the SiC MOSFET through a diode D5. 9. The SiC MOSFET drive circuit according to claim 2, wherein the protection execution circuit comprises: an initialization subcircuit, a latch subcircuit, a signal execution circuit and a prevention subcircuit; wherein, The initialization sub-circuit is connected to the first voltage source V1, the latch sub-circuit, the signal execution sub-circuit and the prevention sub-circuit; The latch subcircuit is connected to the undervoltage detection circuit, the first voltage source V1 and the signal execution subcircuit; the signal execution subcircuit connects the level shift circuit and the prevention subcircuit; The prevention subcircuit connects the level shift circuit and the drive auxiliary circuit. 10. The SiC MOSFET drive circuit according to claim 1, wherein the overvoltage suppression circuit comprises: a transistor Q20, a Zener transistor D2, a Zener transistor D11, a diode D14, a diode D16, a diode D18, and a diode D20 , resistor R22, resistor R23, resistor R24, resistor R34 and capacitor C6; among them, After the diode D18, the capacitor C6, the diode D20 and the resistor R34 are connected in series in sequence, they are connected between the collector and the base of the transistor Q20; The diode D18 and the node connected to the capacitor C6 are sequentially connected to the emitter of the transistor Q20 through the diode D14 and the resistor R22; The voltage regulator tube D11 is connected between the emitter and the collector of the triode; At the node where the capacitor C6 is connected to the diode D20, it is sequentially connected to the gate of the SiC MOSFET through the diode D16 and the resistor R23; At the node where the diode D20 is connected with the resistor R34, it is connected to the ground terminal; The resistor R24 is connected between the emitter and the base of the transistor Q20; The emitter of the transistor Q20 is connected to the drain of the SiC MOSFET through the regulator D2.