Advanced gate drivers for silicon carbide bipolar junction transistors
A gate driver circuit comprises a sensor, an amplifier, a regulator and a gate driver. The sensor is configured to sense a collector-emitter voltage and includes a first resistor and a second resistor connected in series, a high voltage diode connected between the series connected first and second resistors and a first capacitor connected parallel to the second resistor. The amplifier is configured to amplify a sensor output voltage and includes a non-inverting operational amplifier controlled by means of a plurality of resistors, a voltage follower connected to an output terminal of the non-inverting operational amplifier through a first diode and a third resistor connected across the first diode and the voltage follower. The regulator is configured to regulate a regulator output voltage based on an amplifier voltage. The gate driver is configured to connect/disconnect the regulator output voltage to the base terminal of the BJT.
1. A gate driver circuit, comprising:
a sensor connected between a collector terminal and an emitter terminal of a bipolar junction transistor (BJT), the sensor configured to sense and measure a collector-emitter voltage V CE ;
a regulator connected to an amplifier having an amplifier output voltage and configured to regulate a regulator output voltage based on the amplifier output voltage; and
a gate driver connected to a regulator output terminal of the regulator and configured to connect/disconnect the regulator output voltage to a base terminal of the BJT;
wherein the output voltage of the regulator is controlled by an inductor and a capacitor connected at the regulator output terminal.
2. The gate driver circuit of claim 1 wherein the sensor comprises a first resistor and a second resistor connected in series, a high voltage diode with an anode connected between the series connected first and second resistors and the cathode connected to the collector terminal of the BJT and a first capacitor connected parallel to the second resistor.
3. The gate driver circuit of claim 1 wherein the amplifier comprises a non-inverting operational amplifier controlled by means of a plurality of resistors, a voltage follower connected to an output terminal of the non-inverting operational amplifier by means of a first diode and a third resistor connected across the voltage follower and the first diode configured to provide the output of the amplifier.
4. The gate driver circuit of claim 1 wherein the output voltage of the regulator is controlled by an inductor and a capacitor connected at a regulator output terminal.
5. The gate driver circuit of claim 1 wherein the sensor is a high voltage decoupling diode.
6. The gate driver circuit of claim 1 wherein the sensor is a Zener diode voltage clamp.
7. The gate driver circuit of claim 1 wherein the sensor is configured to measure the collector-emitter voltage V CE during the ON state of the BJT.
8. The gate driver circuit of claim 1 wherein a high voltage decoupling diode protects the circuitry comprising the amplifier and the regulator, from high voltage during the OFF state of the BJT.
9. The gate driver circuit of claim 1 wherein the sensor output voltage is proportional to the collector current of the BJT with an additional offset.
10. The gate driver circuit of claim 1 wherein the amplifier output is used as a voltage reference to the regulator.
11. The gate driver circuit of claim 1 wherein the regulator is a synchronous buck converter.
12. The gate driver circuit of claim 1 wherein the regulator provides voltage to the gate driver to provide a continuous supply of base current to maintain the BJT in ON state with minimal conduction losses.
13. The gate driver circuit of claim 12 wherein the gate driver optimizes the base current based on the collector-emitter voltage by adjusting the supply voltage of the gate driver thereby minimizing the power consumption.
14. The gate driver circuit of claim 12 wherein the gate driver output voltage is adjusted during the conducting state of the BJT.
15. The gate driver circuit of claim 12 wherein the gate driver optimizes the base current by monitoring the effect of temperature on the DC current gain.
16. A gate driver circuit for a Silicon Carbide Bipolar Junction Transistor (SiC BJT), comprising:
a sensor connected between a collector terminal and an emitter terminal of the SiC BJT and configured to sense and measure a collector-emitter voltage V CE , the sensor having a first resistor and a second resistor connected in series, a high voltage diode with an anode connected between the series connected first and second resistors and the cathode connected to the collector terminal of the SiC BJT and a first capacitor connected parallel to the second resistor;
a regulator connected to an amplifier having an amplifier voltage and configured to regulate a regulator output voltage based on the amplifier voltage; and
a gate driver connected to the regulator output terminal of the regulator and configured to provide an instantaneous base current based on the collector-emitter voltage of the SiC BJT;
whereby the regulator regulates the voltage of the gate driver to generate the instantaneous proportional base current based on the collector-emitter voltage and monitor the effect of temperature on the DC current gain during the conducting state of the SiC BJT thereby minimizing the driver losses.