Solid state pre-charge module

1. A pre-charge module comprising:

a relay;

a transistor connected to the relay and to a power supply; and

a solid state device connected to a gate of the transistor, the solid state device controlling switching of the transistor such that the transistor is switched off when a voltage at a source of the transistor approaches a voltage at a drain of the transistor, to switch off the solid state device such that a capacitor is pre-charged, and providing a floating ground.

2. A pre-charge module in accordance with claim 1 , wherein the transistor comprises a metal-oxide-semiconductor field-effect transistor (MOSFET).

3. A pre-charge module in accordance with claim 1 , wherein the solid state device comprises a driver component driving the gate of the transistor at a fifty percent duty cycle.

4. A pre-charge module in accordance with claim 1 , wherein the solid state device comprises a self-oscillating half-bridge driver.

5. A pre-charge module in accordance with claim 1 , wherein the solid state device comprises a floating ground integrated circuit chip.

6. A pre-charge module in accordance with claim 1 , wherein the relay comprises an automotive grade electromechanical relay having a rating of twelve volts.

7. A pre-charge module in accordance with claim 1 , further comprising an optocoupler connected between a low (LO) output of the solid state device and the gate of the transistor.

8. A pre-charge module in accordance with claim 1 , wherein a normally open contact of the relay is connected to the power supply providing at least 300 volts.

9. A pre-charge module in accordance with claim 1 , further comprising a resistor and a capacitor and wherein the solid state device comprises a half-bridge driver, with the resistor and the capacitor setting a time period before the transistor is switched on.

10. A pre-charge module in accordance with claim 1 , wherein the transistor is connected to a capacitor to be pre-charged and the transistor is switched off upon the capacitor reaching a full charge, wherein the transistor is switched on by the solid state device after a predetermined time delay based on values of a capacitor and resistor connected to the solid state device such that pre-charging is controlled automatically with the predetermined time delay.

11. A pre-charge module in accordance with claim 1 , wherein the transistor is connected to a capacitor to be pre-charged and the transistor is switched off upon the capacitor being charged to a predetermined capacity.

12. A pre-charge module in accordance with claim 1 , wherein the transistor is connected to a high voltage power supply.

13. A pre-charge module in accordance with claim 1 , further comprising a Zener diode connected to the solid state device reducing a voltage to the solid state device.

14. A pre-charge module comprising:

a relay;

a transistor connected to the relay;

a solid state device connected to the transistor, the solid state device controlling switching of the transistor and having a floating ground; and

a photocoupler connected to a ground switch, the ground switch connected to the relay.

15. A pre-charge architecture comprising:

a capacitor connected to a main contactor; and

a pre-charge module including a floating ground solid state device with electromechanical isolation, wherein the pre-charge module is connected across the main contactor, the pre-charge module having an electrical circuit that sets the delay and charging time for the capacitor to control a pre-charging of the capacitor and automatically switches off when the capacitor is pre-charged, the electrical circuit including a driver component switched by a transistor, wherein the transistor switching is determined based on a capacitor and resistor arrangement defining a predetermined pre-charge level for the capacitor.

16. A pre-charge architecture in accordance with claim 15 , wherein the capacitor has a capacitance of at least 1000 microfarads.

17. A pre-charge architecture in accordance with claim 15 , wherein the pre-charge module comprises a relay and wherein contacts of the relay are connected to a power source of at least 300 volts.

18. A pre-charge architecture in accordance with claim 15 , wherein the capacitor is part of a hybrid electric vehicle (HEV).

19. A pre-charge architecture in accordance with claim 15 , wherein the pre-charge module comprises a low voltage relay having a typical operating voltage of about twelve volts.

20. A pre-charge architecture in accordance with claim 15 , wherein the pre-charge module comprises a metal-oxide-semiconductor field-effect transistor (MOSFET) with the switching of the MOSFET controlled by the solid state device and an optocoupler connected between the solid state device and a gate of the MOSFET.