Solid state switch

Abstract

An intake air heating system for an internal combustion engine is disclosed and includes an electric heater that heats the intake air and a control module that switches a voltage to the electric heater based on a control signal. The control module includes a gate drive module that includes a bootstrap charge pump module and generates a gate drive signal based on the control signal and that is referenced to the voltage. The control module also includes a power module that switches the power to the electric heater based on the gate drive signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of an intake-air heater system;

FIG. 2 is a schematic drawing of a power module of the circuit of FIG. 1;

FIG. 3 is a schematic of a first embodiment of a gate driver module of the system of FIG. 1;

FIG. 4 is a schematic of a second embodiment of a gate driver module of the system of FIG. 1;

FIG. 5 is a plan view of a protective housing and thermal mass for the power module of FIG. 2;

FIG. 6 is a plan view of the protective housing and thermal mass of FIG. 5 that includes the gate drive module of FIG. 4; and

FIG. 7 is a timing chart showing an example of heater power as a function of time.

Claims

1. An intake air heating system for an internal combustion engine, comprising: an electric heater that heats the intake air; anda control module that switches a voltage to the electric heater based on a control signal, the control module comprising a gate drive module that includes a bootstrap charge pump module and generates a gate drive signal based on the control signal and that is referenced to the voltage; anda power module that switches the power to the electric heater based on the gate drive signal.

2. The system of claim 1 wherein the control signal is a pulse width modulated (PWM) signal.

3. The system of claim 1 wherein the bootstrap charge pump module provides sufficient charge to drive the power module at 100% duty cycle.

4. The system of claim 1 wherein the power module includes a plurality of transistors that each provide an equal amount of current to the electric heater.

5. The system of claim 4 wherein the transistors are field effect transistors.

6. The system of claim 4 wherein the transistors are insulated gate bipolar transistors.

7. The system of claim 4 wherein each transistor includes a gate that receives the gate drive signal.

8. The system of claim 7 further comprising resistances in series with respective ones of the gates.

9. The system of claim 8 wherein values of the resistances are equal.

10. The system of claim 1 wherein the gate drive module includes an integrated circuit; anda printed circuit board that includes a first set of solder pads that accommodate a first package type for the integrated circuit and a second set of solder pads that accommodate a second package type for the integrated circuit.

11. The system of claim 1 wherein the power module is configured as a high-side driver of the electric heater.

12. The system of claim 1 wherein the gate drive module includes a second charge pump module that generates a second voltage and wherein the gate drive signal is based on the second voltage and a voltage that is generated by the bootstrap charge pump module.

13. The system of claim 1 wherein the power module includes a printed circuit board that includes circuit traces on an electrically insulating film and a thermal layer that is mated to film.

14. The system of claim 13 wherein the thermal layer is formed of at least one of aluminum and copper.

15. The system of claim 14 further comprising a thermal mass that draws heat from the thermal layer.

16. The system of claim 15 wherein the thermal mass includes heat dissipating projections.

17. The system of claim 1 further comprising an optoisolator that generates the control signal.

18. A method for heating the intake air of an internal combustion engine, comprising: generating a control signal that toggles between first and second voltages and indicates a desired degree of heating;converting the control signal to a gate signal that toggles between third and fourth voltages;generating a switched power signal based on the gate signal; andconverting the switch power signal to heat that heats the intake air.

19. The method of claim 18 wherein the control signal is a pulse width modulated (PWM) signal.

20. The method of claim 19 wherein the control signal includes a 100% duty cycle.

21. The method of claim 18 wherein the generating step includes combining currents from a plurality of current sources to generate the switched power signal.

22. The method of claim 21 further comprising switching each current source on and off based on the gate signal.

23. The method of claim 18 further comprising manipulating the gate signal to control a switching time of the switched power signal.

24. The method of claim 13 further comprising generating one of the third and fourth voltages from a voltage that drives the switched power signal.

25. An intake air heating system for an internal combustion engine, comprising: an electric heater for heating the intake air; anda control module that receives a control signal and switches power to the electric heater based on the control signal, control module comprising a gate drive module that generates a gate drive signal based on the control signal;a first terminal that receives current passing through the electric heater;a second terminal that outputs current passing through the electric heater; anda plurality of field effect transistors that are controlled by the gate drive signal and arranged to switch an equal portion of the current on and off between the first and second terminals.

26. The intake air heating system of claim 25 wherein each of the field effect transistors includes a gate that connects in series with a respective resistor and the gates receive the gate drive signal through the respective resistors.

27. A circuit for switching power to a resistive load, comprising: an input that receives a control signal;a gate drive module that includes a first charge pump module that generates a first voltage, a bootstrap charge pump module that generates a second voltage, and that generates a gate drive signal that is based on the control signal and that has an amplitude based on the second voltage and a voltage of the power switched to the resistive load; anda power module that switches the power to the resistive load based on the gate drive signal wherein the control signal represents an amount of power that is desired to be dissipated by the resistive load.

28. The system of claim 27 wherein the control signal is a pulse width modulated (PWM) signal.

29. The system of claim 27 wherein the bootstrap charge pump module provides sufficient charge to drive the power module at 100% duty cycle.

30. The system of claim 27 wherein the power module includes a plurality of transistors that each provide an equal amount of current to the resistive load.

31. The system of claim 30 wherein the transistors are field effect transistors.

32. The system of claim 30 wherein the transistors are insulated gate bipolar transistors.

33. The system of claim 30 wherein each transistor includes a gate that receives the gate drive signal.

34. The system of claim 33 further comprising resistances in series with respective ones of the gates.

35. The system of claim 34 wherein values of the resistances are equal.

36. The system of claim 27 wherein the gate drive module includes an integrated circuit; anda printed circuit board that includes a first set of solder pads that accommodate a first package type for the integrated circuit and a second set of solder pads that accommodate a second package type for the integrated circuit.

37. The system of claim 27 wherein the power module is configured as a high-side driver of the resistive load.

38. The system of claim 27 wherein the gate drive module includes a second charge pump module that generates a second voltage and wherein the gate drive signal is based on the second voltage and a voltage that is generated by the bootstrap charge pump module.

39. The system of claim 27 wherein the power module includes a printed circuit board that includes circuit traces on an electrically insulating film and a thermal layer that is mated to film.

40. The system of claim 39 wherein the thermal layer is formed of at least one of aluminum and copper.

41. The system of claim 40 further comprising a thermal mass that draws heat from the thermal layer.

42. The system of claim 41 wherein the thermal mass includes heat dissipating projections.

43. The system of claim 27 further comprising an optoisolator that generates the control signal.

44. The system of claim 27 wherein the resistive load is an intake air heater.