System and method for providing symmetric, efficient bi-directional power flow and power conditioning
A system and method for providing symmetric, efficient bi-directional power flow and power conditioning for high-voltage applications. Embodiments include a first vertical-channel junction gate field-effect transistor (VJFET), a second VJFET, a gate drive coupled to the first VJFET gate and the second VJFET gate. Both VJFETs include a gate, drain (D 1 and D 2 ), and a source, and have gate-to-drain and gate-to-source built-in potentials. The first VJFET and the second VJFET are connected back-to-back in series so that the sources of each are shorted together at a common point S. The gate drive applies an equal voltage bias (V G ) to both the gates. The gate drive is configured to selectively bias V G so that current flows through the VJFETs in the D 1 to D 2 direction, flows through the VJFETs in the D 2 to D 1 direction or voltages applied to D 1 of the first VJFET or D 2 of the second VJFET are blocked.
1. A system for providing symmetric, efficient bi-directional power flow and power conditioning for high-voltage applications, comprising:
a first vertical-channel junction field-effect transistor (VJFET), wherein the first VJFET includes a gate, drain (D 1 ), and source, and has gate-to-drain and gate-to-source built-in potentials;
a second VJFET, wherein the second VJFET includes a gate, drain (D 2 ), and source, and has gate-to-drain and gate-to-source built-in potentials and the first VJFET and the second VJFET are connected back-to-back in series so that the first VJFET source and the second VJFET source are shorted together at a common point S; and
a gate drive coupled to the first VJFET gate and the second VJFET gate, referenced to the common point S, connected to the drain D 1 of the first VJFET only through internal circuitry of the first VJFET, and connected to the drain D 2 of the second VJFET only through internal circuitry of the second VJFET, wherein the gate drive applies an equal voltage bias (V G ) to both the first VJFET gate and the second VJFET gate and the gate drive is configured to selectively bias V G so that the system allows symmetric current to flow through the first VJFET and the second VJFET in the D 1 to D 2 direction or to flow through the second VJFET and the first VJFET in the D 2 to D 1 direction, wherein the current flowing in the D 1 to D 2 direction is symmetric to the current flowing in the D 2 to D 1 direction, or so that the system blocks voltages applied to D 1 of the first VJFET or D 2 of the second VJFET.
2. The system of claim 1 wherein the gate-to-drain and gate-to-source pn junctions of the first VJFET and the second VJFET are biased below their built-in potentials.
3. The system of claim 1 wherein the first VJFET and the second VJFET are fabricated from a wide-bandgap semiconductors chosen from the list consisting of silicon carbide, gallium nitride, gallium arsenide, and diamond.
4. The system of claim 1 wherein V G may be biased so that the system may block high voltages in excess of 0.5 Kilovolt (kV).
5. The system of claim 1 wherein V G is selectively biased to allow current to flow through the first VJFET and the second VJFET in the D 1 to D 2 direction by setting V G equal to or less than the gate-to-drain built-in potential of the second VJFET minus the absolute value of the voltage measured across D 2 to S.
6. The system of claim 1 wherein V G is selectively biased to allow current to flow through the second VJFET and the first VJFET in the D 2 to D 1 direction by setting V G equal to or less than the gate-to-drain built-in potential of the first VJFET minus the absolute value of the voltage measured across D 1 to S.
7. The system of claim 1 wherein V G is selectively biased to block voltages applied to D 1 of the first VJFET by setting V G equal to or less than a negative voltage sufficient to block the applied voltage, wherein the sufficient negative voltage is determined by the blocking voltage characteristics of the first VJFET.
8. The system of claim 1 wherein V G is selectively biased to block voltages applied to D 2 of the second VJFET by setting V G equal to or less than a negative voltage sufficient to block the applied voltage, wherein the sufficient negative voltage is determined by the blocking voltage characteristics of the second VJFET.
9. The system of claim 1 wherein the built-in potential of each VJFET is approximately 2.7 volts.
10. The system of claim 1 in which the gate drive includes control circuitry configured to selectively set V G .
11. The system of claim 1 in which the gate drive sets the bias V G .
12. The system of claim 10 in which the gate drive determines at what voltage to bias V G based on a received signal.
13. A solid-state circuit breaker comprising the system of claim 1 .
14. A method for providing symmetric, efficient bi-directional power flow and power conditioning for high-voltage applications, comprising:
providing a first vertical-channel junction gate field-effect transistor (VJFET), wherein the first VJFET includes a gate, drain (D 1 ), and source, and has gate-to-drain and gate-to-source built-in potentials;
providing a second VJFET, wherein the second VJFET includes a gate, drain (D 2 ), and source, and has gate-to-drain and gate-to-source built-in potentials;
connecting the first VJFET and the second VJFET back-to-back in series so that the first VJFET source and the second VJFET source are shorted together at a common point S;
coupling a gate drive to the first VJFET gate and the second VJFET gate wherein the gate drive is referenced only to the common point S, connected to the drain D 1 of the first VJFET only through internal circuitry of the first VJFET, and connected to the drain D 2 of the second VJFET only through internal circuitry of the second VJFET; and
selectively applying an equal voltage bias (V G ) from the gate drive to both the first VJFET gate and the second VJFET gate so that symmetric current flows through the first VJFET and the second VJFET in the D 1 to D 2 direction or flows through the second VJFET and the first VJFET in the D 2 to D 1 direction, wherein the current flowing in the D 1 to D 2 direction is symmetric to the current flowing in the D 2 to D 1 direction, or so that voltages applied to D 1 of the first VJFET or D 2 of the second VJFET are blocked.
15. The method of claim 14 wherein the gate-to-drain and gate-to-source pn junctions of the first VJFET and the second VJFET are biased below their built-in potentials.
16. The method of claim 14 comprising the gate drive determining V G .
17. The method of claim 14 wherein the gate drive determining V G comprises the gate drive receiving a control signal.
18. The method of claim 14 wherein the selectively applying comprises the gate drive selectively biasing V G to allow current to flow through the first VJFET and the second VJFET in the D 1 to D 2 direction by setting V G equal to or less than the gate-to-drain built-in potential of the second VJFET minus the absolute value of the voltage measured across D 2 to S.
19. The method of claim 14 wherein the selectively applying comprises the gate drive selectively biasing V G to allow current to flow through the second VJFET and the first VJFET in the D 2 to D 1 direction by setting V G equal to or less than the gate-to-drain built-in potential of the first VJFET minus the absolute value of the voltage measured across D 1 to S.
20. The method of claim 14 wherein the selectively applying comprises the gate drive selectively biasing V G to block voltages applied to D 1 of the first VJFET by setting V G equal to or less than a negative voltage sufficient to block the applied voltage, wherein the sufficient negative voltage is determined by the blocking voltage characteristics of the first VJFET.
21. The method of claim 14 wherein the selectively applying comprises the gate drive selectively biasing V G to block voltages applied to D 2 of the second VJFET by setting V G equal to or less than a negative voltage sufficient to block the applied voltage, wherein the sufficient negative voltage is determined by the blocking voltage characteristics of the second VJFET.