Method, system, and apparatus for efficiently driving a transistor with a booster in voltage supply
View Patent ↗A method, system, and apparatus for driving a Silicon Carbide (SiC) Junction Field Effect Transistor (JFET) are provided. A boosting capacitor is used in combination with two drivers to efficiently provide a boosting current to the SiC JFET and then a holding current to the SiC JFET. The boosting capacitor, upon discharge, creates the boosting current and once discharged the holding current is provided by one of the first and second drivers.
1. An electrical isolation circuit comprising a high-voltage input side and a low-voltage output side, comprising:
a coupler configured to be connected between the input side and the output side, the coupler comprising driver logic, a first driver, and a second driver, wherein the first driver is configured to drive a Junction Field-Effect Transistor (JFET) on the output side for a first amount of time, and wherein the second driver is configured to provide a boosting voltage to the first driver via a boosting capacitor, wherein the boosting capacitor is configured to boost and activate the JFET by discharging and providing current to the JFET for an amount of time that is less than the first amount of time.
2. The electrical isolation circuit of claim 1 , wherein the JFET is at least one of a Silicon Carbide (SiC) JFET and a plurality of SiC JFETs connected in parallel with one another.
3. The electrical isolation circuit of claim 1 , wherein the coupler comprises a light detector configured to convert light energy into an electrical signal that is transmitted to the driver logic.
4. The electrical isolation circuit of claim 1 , wherein the boosting capacitor is external to the coupler.
5. The electrical isolation circuit of claim 1 , wherein the first driver comprises a first P-type Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) (PMOS) and a first N-type MOSFET (NMOS), wherein the second driver comprises a second PMOS and a second NMOS, wherein a drain of the first PMOS is connected to a drain of the first NMOS at an output of the first driver, wherein a drain of the second PMOS is connected to a drain of the first NMOS at an output of the second driver.
6. The electrical isolation circuit of claim 5 , wherein a source of the first NMOS and a source of the second NMOS are connected to a common voltage and wherein both the first PMOS and the second PMOS are turned on in response to a single input, S 1 , exceeding a predetermined logic supply level.
7. The electrical isolation circuit of claim 1 , wherein the boosting voltage provided to the first driver causes the first driver to provide a peak current to the JFET that is sufficient to switch the JFET from an OFF state to an ON state and wherein the peak current is greater than a hold current required to maintain the JFET in the ON state after it has been switched from the OFF state to the ON state.
8. The electrical isolation circuit of claim 7 , wherein the peak current is created in response to the boosting capacitor discharging.
9. The electrical isolation circuit of claim 1 , wherein the output side provides a first output current to a plurality of JFETs connected in parallel.
10. The electrical isolation circuit of claim 9 , further comprising at least one current buffer provided between the plurality of JFETs and the output of the first driver.
11. The electrical isolation circuit of claim 10 , wherein the at least one current buffer comprises a first Bipolar Junction Transistor (BJT) and a second BJT.
12. The electrical isolation circuit of claim 11 , wherein the first BJT directly receives an output from the first driver and wherein the second BJT directly receives an output from the second driver.
13. The electrical isolation circuit of claim 12 , wherein the first BJT shares a supply source with the first driver and wherein the second BJT shares a supply source with the second driver.
14. The electrical isolation circuit of claim 11 , wherein a gate resistor is provided between an output of the first BJT and the boosting capacitor.
15. The electrical isolation circuit of claim 1 , wherein the driver logic receives an input from a light detector and wherein the input received from the light detector controls operations of the driver logic.
16. The electrical isolation circuit of claim 15 , wherein the light detector comprises at least one of a photodiode, a photoresistor, a photovoltaic cell, a phototransistor, and an Integrated Circuit (IC) chip comprising one or more photodetector components.
17. The electrical isolation circuit of claim 1 , further comprising:
a diode provided between the boosting capacitor and a supply voltage, wherein the diode is configured to block the supply voltage from discharge of the boosting capacitor.
18. The electrical isolation circuit of claim 17 , further comprising:
a holding resistor provided between the boosting capacitor and diode, wherein the holding resistor along with the boosting capacitor set current provided by the supply voltage to the first driver.
19. The electrical isolation circuit of claim 1 , wherein the driver logic is configured to simultaneously control the first and second drivers with only a single input.
20. The electrical isolation circuit of claim 1 , wherein the driver logic comprises at least one of firmware, an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), an analog circuit element, and a digital circuit element.