Supply unit for a driver circuit and method for operating same

1. A method of operating a power supply unit, the method comprising the steps of:

operating a first and a second switch to an “On” position;

operating said first switch to a “Off” position and causing a flow of a first free-wheeling current through a first free-wheeling current path;

measuring a value of said first free-wheeling current;

controlling the switching of said second switch responsive to said value of said first free-wheeling current; and

regulating power from said power supply unit.

2. The method of claim 1 , further comprising the steps of:

operating said first and said second switch to the “On” position;

operating said second switch to a “Off” position and causing the flow of a second free-wheeling current through a second free-wheeling current path;

measuring a value of said second free-wheeling current; and

controlling the switching of said first switch responsive to said value of said second free-wheeling current.

3. The method of claim 2 , further comprising the steps of:

designating said first free-wheeling current as faulty when the value of said first free-wheeling current is less than a first prescribed threshold value; and

designating said second free-wheeling current as faulty when the value of said second free-wheeling current is less than a second prescribed threshold value.

4. The method of claim 3 , comprising the step of maintaining said second switch in the “On” position when said first free-wheeling current is faulty.

5. The method of claim 3 , comprising the step of maintaining said first and said second switch in the “Off” position when said first free-wheeling current is faulty.

6. The method of claim 3 , comprising the step of maintaining said first switch in the “On” position when said second free-wheeling current is faulty.

7. The method of claim 3 , comprising the step of maintaining said first and said second switch in the “Off” position when said second free-wheeling current is faulty.

8. The method of claim 1 , further comprising the steps of:

generating a first control signal for operating said second switch; and

generating a second control signal for operating said first switch.

9. The method of claim 8 , comprising the steps of:

generating said first control signal from a first periodic signal; and

generating said second control signal from a second periodic signal.

10. The method of claim 8 , comprising the steps of:

generating said first control signal from a first clock signal; and

generating said second control signal from a second clock signal.

11. The method of claim 8 , comprising the step of synchronizing said first and said second control signals to a clock signal.

12. The method of claim 8 , further comprising the steps of:

generating said first control signal when said first free-wheeling current is not faulty; and

generating said second control signal when said second free-wheeling current is not faulty.

13. The method of claim 1 operating a power electronics circuit.

14. The method of claim 13 providing power to said power electronics circuit.

15. The method of claim 1 operating an electric motor.

16. The method of claim 1 providing power to an inductive converter, said method further comprising the steps of:

operating said first switch between said “On” and said “Off” positions; and

operating said second switch between said “On” and said “Off” positions.

17. A power supply unit comprising:

an inductive converter;

a first free-wheeling current path comprising:

a first switch connected in series with said inductive converter, said first switch operable between an “On” position and a “Off” position; and

a first means for measuring a first free-wheeling current flowing through said first free-wheeling current path; and

a second free-wheeling current path comprising:

a second switch connected in series with said inductive converter, said second switch operable between an “On” position and a “Off” position; and

a second means for measuring a second free-wheeling current flowing through said second free-wheeling current path.

18. The power supply unit of claim 17 , wherein:

said first means for measuring said first free-wheeling current includes a first current sensor; and

said second means for measuring said second free-wheeling current includes a second current sensor.

19. The power supply unit of claim 17 , further comprising:

a first control circuit measuring said first free-wheeling current and operating said first switch between said “On” and “Off” positions; and

a second control circuit measuring said second free-wheeling current and operating said second switch between said “On” and “Off” positions.

20. The power supply unit of claim 19 , wherein

said second control circuit receives a first signal from said first control circuit; and

said first control circuit receives a second signal from said second control circuit.

21. The power supply unit of claim 20 , wherein said first signal is a first periodic or clock signal generated by said first control circuit and wherein said second signal is a second periodic or clock signal generated by said second control circuit.

22. The power supply unit of claim 20 , wherein said first signal is generated by said first control circuit from a first periodic signal or a clock signal and wherein said second signal is generated by said second control circuit from a second periodic signal or a clock signal.

23. The power supply unit of claim 17 , configured to operate a power electronics circuit.

24. The power supply unit of claim 23 , configured to provide power to said power electronics circuit.

25. The power supply unit of claim 17 , configured to operate an electric motor.

26. The power supply unit of claim 17 , wherein said inductive converter provides power in response to operating said first switch and said second switch between said “On” and “Off” positions.

27. The power supply unit of claim 17 , configured to generate

said first free-wheeling current in response to operating said first switch to said “Off” position; and

said second free-wheeling current in response to operating said second switch to said “Off” position.

28. The power supply unit of claim 17 , wherein said inductive converter is a transformer.

29. The power supply unit of claim 17 , wherein said first switch does not operate when said first free-wheeling current is less than a first prescribed value.

30. The power supply unit of claim 17 , wherein said second switch does not operate when said second free-wheeling current is less than a second prescribed value.

31. The power supply unit of claim 17 , wherein said first free-wheeling current path further comprises a first free-wheeling diode.

32. The power supply unit of claim 17 , wherein said second free-wheeling current path further comprises a second free-wheeling diode.

33. The power supply unit of claim 17 , wherein said first switch is a first field effect transistor.

34. The power supply unit of claim 17 , wherein said second switch is a second field effect transistor.