Motor drive with silicon carbide MOSFET switches
Motor drive power conversion systems are provided including a rectifier and a switching inverter, wherein the switching devices of the rectifier, the inverter and/or of a DC/DC converter are silicon carbide switches, such as silicon carbide MOSFETs. Driver circuits are provided for providing bipolar gate drive signals to the silicon carbide MOSFETs, including providing negative gate-source voltage for controlling the off state of enhancement mode low side drivers and positive gate-source voltage for controlling the off state of enhancement mode high side drivers.
1. A power conversion system, comprising:
an active rectifier comprising a plurality of silicon carbide rectifier switching devices coupled to receive AC input power from an external power source, and operative to provide a DC output signal according to a plurality of rectifier switching control signals, the active rectifier including a plurality of low side silicon carbide switches operatively coupled with a DC bus connection;
a switching inverter to convert the DC output signal to provide an AC output to drive a load;
a controller operative to generate the rectifier switching control signals to operate the rectifier switching devices; and
a driver circuit operative to provide a set of the switching control signals to the low side silicon carbide switches in a first state at a first voltage above a voltage of the DC bus connection and in a second state at a second voltage below the voltage of the DC bus connection; and
a driver supply circuit, including:
a first voltage node providing a first supply voltage to the driver circuit for providing the set of the switching control signals in the first state at the first voltage above the voltage of the DC bus connection,
a second voltage node providing a second supply voltage to the driver circuit for providing the second set of the switching control signals in the second state at the second voltage below the voltage of the DC bus connection,
an intermediate node connected to the DC bus connection,
a zener diode with an anode connected to the intermediate node and a cathode connected to the first voltage node to provide a positive voltage at the first voltage node with respect to the intermediate node,
a capacitor connected between the intermediate node and the second voltage node to provide a negative voltage at the second voltage node with respect to the intermediate node, and
a DC supply providing a positive DC voltage between the first and second voltage nodes.
2. The power conversion system of claim 1 , wherein the low side silicon carbide switches are enhancement mode devices.
3. The power conversion system of claim 1 , wherein the low side silicon carbide switches are depletion mode devices.
4. The power conversion system of claim 1 , wherein the power conversion system is a voltage source converter motor drive.
5. The power conversion system of claim 1 , wherein the power conversion system is a current source converter motor drive.
6. The power conversion system of claim 1 , wherein the low side silicon carbide switches are P-channel silicon carbide MOSFETs.
7. The power conversion system of claim 1 , wherein the low side silicon carbide switches are N-channel silicon carbide MOSFETs.
8. The power conversion system of claim 1 :
wherein the rectifier includes:
a plurality of high side silicon carbide switches operatively coupled with a first DC bus connection, wherein the plurality of low side silicon carbide switches are operatively coupled with a second DC bus connection; and
wherein the driver circuit is operative to:
provide a second set of switching control signals to the high side silicon carbide switches in a first state at a third voltage above a voltage of the first DC bus connection and in a second state at a fourth voltage below the voltage of the first DC bus connection.
9. The power conversion system of claim 8 , wherein the driver supply circuit includes:
a second driver supply circuit, including:
a third voltage node providing a third supply voltage to the driver circuit for providing the second set of the switching control signals in the first state at the third voltage above the voltage of the first DC bus connection,
a fourth voltage node providing a fourth supply voltage to the driver circuit for providing the second set of the switching control signals in the second state at the fourth voltage below the voltage of the first DC bus connection,
a second intermediate node,
a second zener diode with an anode connected to the second intermediate node and a cathode connected to the third voltage node to provide a positive voltage at the third voltage node with respect to the second intermediate node,
a second capacitor connected between the second intermediate node and the fourth voltage node to provide a negative voltage at the fourth voltage node with respect to the second intermediate node, and
a second DC supply providing a positive DC voltage between the third and fourth voltage nodes.
10. The power conversion system of claim 9 , wherein the first DC supply includes a first transformer secondary winding and a rectifier; and wherein the second DC supply includes a second transformer secondary winding and a second rectifier.
11. The power conversion system of claim 8 , wherein the low side silicon carbide switches are enhancement mode devices.
12. The power conversion system of claim 8 , wherein the low side silicon carbide switches are depletion mode devices.
13. The power conversion system of claim 11 , comprising:
a driver supply circuit, including:
a first voltage node providing a first supply voltage to the driver circuit for providing the set of the switching control signals in the first state at the first voltage above the voltage of the DC bus connection,
a second voltage node providing a second supply voltage to the driver circuit for providing the second set of the switching control signals in the second state at the second voltage below the voltage of the DC bus connection,
an intermediate node connected to the DC bus connection,
a zener diode with an anode connected to the intermediate node and a cathode connected to the first voltage node to provide a positive voltage at the first voltage node with respect to the intermediate node,
a capacitance connected between the intermediate node and the second voltage node to provide a negative voltage at the second voltage node with respect to the intermediate node, and
a DC supply providing a positive DC voltage between the first and second voltage nodes.
14. The power conversion system of claim 13 , wherein the DC supply includes a transformer secondary winding and a rectifier.
15. A power conversion system, comprising:
an inverter comprising a plurality of inverter switching devices coupled to receive DC input power and operative to provide an AC output to drive a load according to a plurality of inverter switching control signals;
a DC/DC converter receiving DC input power and comprising at least one silicon carbide converter switching devices operatively coupled with a DC bus connection to provide a DC output signal to the inverter according to at least one converter switching control signal;
a driver circuit operative to provide the at least one converter switching control signal to the at least one silicon carbide converter switching device in a first state at a first voltage above a voltage of the DC bus connection and in a second state at a second voltage below the voltage of the DC bus connection; and
a driver supply circuit, including:
a first voltage node providing a first supply voltage to the driver circuit for providing the set of the switching control signals in the first state at the first voltage above the voltage of the DC bus connection,
a second voltage node providing a second supply voltage to the driver circuit for providing the second set of the switching control signals in the second state at the second voltage below the voltage of the DC bus connection,
an intermediate node connected to the DC bus connection,
a zener diode with an anode connected to the intermediate node and a cathode connected to the first voltage node to provide a positive voltage at the first voltage node with respect to the intermediate node,
a capacitor connected between the intermediate node and the second voltage node to provide a negative voltage at the second voltage node with respect to the intermediate node, and
a DC supply providing a positive DC voltage between the first and second voltage nodes.
16. The power conversion system of claim 15 , wherein the DC supply includes a transformer secondary winding and a rectifier.
17. The power conversion system of claim 15 , wherein the DC/DC converter provides control power for circuitry of the system.
18. The power conversion system of claim 15 , wherein the at least one silicon carbide converter switching device is an enhancement mode silicon carbide MOSFET.
19. The power conversion system of claim 15 , wherein the DC/DC converter is a flyback converter including a transformer primary winding coupled between a first DC bus connection and the at least one silicon carbide converter switching device, the at least one silicon carbide converter switching device being coupled between the transformer primary winding and a second DC bus connection to control current flow in the transformer primary winding, and wherein the driver circuit is operative to provide the at least one converter switching control signal to the at least one silicon carbide converter switching device in the first state at a first voltage above a voltage of the second DC bus connection and in a second state at a second voltage below the voltage of the second DC bus connection.
20. The power conversion system of claim 19 , comprising:
a driver supply circuit, including:
a first voltage node providing a first supply voltage to the driver circuit for providing the set of the switching control signals in the first state at the first voltage above the voltage of the DC bus connection,
a second voltage node providing a second supply voltage to the driver circuit for providing the second set of the switching control signals in the second state at the second voltage below the voltage of the DC bus connection,
an intermediate node connected to the DC bus connection,
a zener diode with an anode connected to the intermediate node and a cathode connected to the first voltage node to provide a positive voltage at the first voltage node with respect to the intermediate node,
a capacitor connected between the intermediate node and the second voltage node to provide a negative voltage at the second voltage node with respect to the intermediate node, and
a transformer secondary winding and a rectifier providing a positive DC voltage between the first and second voltage nodes.