PWM-pulse control system

• US 6,548,983 B2
• Filed: 06/11/2001
• Issued: 04/15/2003
• Est. Priority Date: 06/13/2000
• Status: Expired due to Term

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Palma, Giuseppe, Avella, Leonardo Dino, Cuceʼ, Antonino
• Primary Examiner(s): Fletcher, Marlon T.
• Assistant Examiner(s): Duda, Rina I.
• Application Number:
  US09/878,718
• Publication Number:
  US 20020050803A1
• Time in Patent Office: 673 Days
• Field of Search: 323/239, 323/324, 318/811, 318/599, 318/798
• US Class Current: 318/599
• CPC Class Codes: H02P 7/29 using pulse modulation
• CPC Class Codes: H02P 7/295 of the kind having one thyristor or the like in series with the power supply and the motor
• CPC Class Codes: H03K 17/08142 in field-effect transistor switches

Abstract

A power modulation control system using PWM pulses is provided. The system comprises an AC voltage generator, an electric load, and a control circuit incorporating at least one rectifier. The electric load is connected between the generator and the rectifier, and first and second monodirectional switches are connected in parallel with the load.

Claims

1. A power modulation control system using PWM pulses and comprising:

an AC voltage generator;

an inductive electric load; and

a PWM control circuit incorporating at least one rectifier, wherein said electric load is connected between said generator and said rectifier, the control circuit including a pair of circuit elements connected in parallel to the load, both circuit elements being turned on if a power transistor is turned off, both circuit elements being turned off if the power transistor is turned on.

2. The control system according to claim 1, further comprising:

first and second monodirectional switches connected to the electric load in parallel.

3. The control system according to claim 2, wherein said first monodirectional switch is connected to said second monodirectional switch in phase opposition.

4. The control system according to claim 2, wherein each of said monodirectional switches comprises a series of a diode transistor and a feedback transistor.

5. The control system according to claim 2, further comprising:

a driving circuit for said monodirectional switches connected to said electric load to detect a line current sensing and drive said monodirectional switches in opposition with respect to said PWM pulses.

6. The control system according to claim 5, wherein said driving circuit comprises:

a first NOR logic gate inserted between said generator and a first terminal of said electric load and connected to a first pair of sensing resistors, wherein said resistors are in turn inserted between said generator and said first terminal of said electric load; and

a second NOR logic gate inserted between said rectifier and a second terminal of said electric load and connected to a second pair of sensing resistors, wherein said second pair of resistors is in turn inserted between said rectifier and said second terminal of said electric load, said sensing resistors detecting a line current sensing in order to supply said NOR logic gates and, through such gates, to drive said monodirectional switches.

7. The control system according to claim 6, wherein said NOR logic gates comprise respective pairs of bipolar transistors inserted, in parallel to each other, between a first and a second voltage reference and having base terminals connected to said sensing resistors.

8. The control system according to claim 7, wherein said bipolar transistors have common collector terminals to form respective drive circuit nodes for said monodirectional switches.

9. The control system according to claim 1, wherein said electric load is a universal motor operating with an alternating current.

10. The control system according to claim 1, wherein said rectifier is a diode bridge.

11. The control system according to claim 1, wherein said control circuit has a circuit leg connected in parallel to an output of the rectifier and comprising the power transistor supplied by said PWM pulses, as well as a snubber circuit in parallel with said circuit leg.

12. The control system according to claim 11, wherein said snubber circuit comprises a diode in parallel with a resistor, and a capacitor connected in series with this parallel connection.

13. A PWM controller comprising:

an AC voltage generator;

a PWM control circuit incorporating at least one rectifier;

an inductive electric load connected between said generator and said rectifier; and

first and second monodirectional switches connected to the electric load in parallel, the first and second monodirectional switches both being turned on if a power transistor is turned off, and the first and second monodirectional switches both being turned off if the power transistor is turned on.

14. The PWM controller according to claim 13, wherein said first monodirectional switch is connected to said second monodirectional switch in phase opposition.

15. The PWM controller according to claim 13, wherein each of said monodirectional switches comprises a series of a diode and a feedback transistors.

16. The PWM controller according to claim 13,

further comprising a driving circuit for said monodirectional switches connected to said electric load so as to detect a line current and to drive said monodirectional switches in opposition with respect to said PWM pulses.

17. The PWM controller according to claim 16, wherein said driving circuit comprises:

a first NOR logic gate inserted between said generator and a first terminal of said electric load and connected to a first pair of sensing resistors, wherein said resistors are in turn inserted between said generator and said first terminal of said electric load; and

a second NOR logic gate inserted between said rectifier and a second terminal of said electric load and connected to a second pair of sensing resistors, wherein said second pair of resistors is in turn inserted between said rectifier and said second terminal of said electric load, said sensing resistors detecting a line current in order to supply said NOR logic gates and, through such gates, to drive said monodirectional switches.

18. The PWM controller according to claim 17, wherein said NOR logic gates comprise respective pairs of bipolar transistors inserted, in parallel to each other, between a first and a second voltage reference and having base terminals connected to said sensing resistors.

19. The PWM controller according to claim 18, wherein said bipolar transistors have common collector terminals to form respective drive circuit node for said monodirectional switches.

20. An electronic device, comprising:

a universal motor operating with an alternating current;

an AC voltage generator connected to one terminal of said motor; and

a PWM controller incorporating at least one rectifier and connected to another terminal of said motor, said PWM controller further comprising first and second monodirectional switches connected to the motor in parallel, the first and second monodirectional switches both being turned on if a power transistor is turned off, and the first and second monodirectional switches both being turned off if the power transistor is turned on.

21. The electronic device according to claim 20, wherein said rectifier is a diode bridge.

22. The electronic device according to claim 20, wherein said PWM controller has a circuit leg connected in parallel to the output of the rectifier and comprising the power transistor supplied by a PWM signal.

23. The electronic device according to claim 20, wherein said first monodirectional switch is connected to said second monodirectional switch in phase opposition.

24. The electronic device according to claim 20, wherein each of said monodirectional switches comprises a series of a diode and a feedback transistor.

25. The electronic device according to claim 20, further comprising:

a driving circuit for said monodirectional switches connected to said motor so as to detect a line current and to drive said monodirectional switches in opposition with respect to said PWM pulses.

26. The electronic device according to claim 25, wherein said driving circuit comprises:

a first NOR logic gate inserted between said generator and a first terminal of said motor and connected to a first pair of sensing resistors, wherein said resistors are in turn inserted between said generator and said first terminal of said motor; and

,

a second NOR logic gate inserted between said rectifier and a second terminal of said motor and connected to a second pair of sensing resistors, wherein said second pair of resistors is in turn inserted between said rectifier and said second terminal of said motor, said sensing resistors detecting a line current in order to supply said NOR logic gates and, through such gates, to drive said monodirectional switches.

27. The electronic device according to claim 26, wherein said NOR logic gates comprise respective pairs of bipolar transistors inserted, in parallel to each other, between a first and a second voltage reference and having the base terminals connected to said sensing resistors.

28. The electronic device according to claim 26, wherein said bipolar transistors have common collector terminals to form respective drive circuit node for said monodirectional switches.

29. The electronic device according to claim 22, further comprising:

a snubber circuit in parallel with said circuit leg.

30. The electronic device according to claim 29, wherein said snubber circuit comprises a diode in parallel with a resistor, and a capacitor connected in series with this parallel connection.

31. A power modulation control system using PWM pulses, the control system comprising:

an AC voltage generator;

an electric load;

a control circuit incorporating at least one rectifier, wherein said electric load is connected between said generator and said rectifier;

first and second monodirectional switches connected to the electric load in parallel; and

a driving circuit for said monodirectional switches connected to said electric load to detect a line current sensing and drive said monodirectional switches in opposition with respect to said PWM pulses, wherein said driving circuit comprises;

a first NOR logic gate inserted between said generator and a first terminal of said electric load and connected to a first pair of sensing resistors, wherein said resistors are in turn inserted between said generator and said first terminal of said electric load; and

a second NOR logic gate inserted between said rectifier and a second terminal of said electric load and connected to a second pair of sensing resistors, wherein said second pair of resistors is in turn inserted between said rectifier and said second terminal of said electric load, said sensing resistors detecting a line current sensing in order to supply said NOR logic gates and, through such gates, to drive said monodirectional switches.

32. The control system according to claim 31 wherein said NOR logic gates comprise respective pairs of bipolar transistors inserted, in parallel to each other, between a first and a second voltage reference and having base terminals connected to said sensing resistors.

33. The control system according to claim 32 wherein said bipolar transistors have common collector terminals to form respective drive circuit nodes for said monodirectional switches.

34. A power modulation control system using PWM pulses, the control system comprising:

an AC voltage generator;

an electric load;

a control circuit incorporating at least one rectifier, wherein said electric load is connected between said generator and said rectifier, wherein said control circuit has a circuit leg connected in parallel to an output of the rectifier and includes a power transistor supplied by said PWM pulses, as well as a snubber circuit in parallel with said circuit leg.

35. The control system according to claim 34 wherein said snubber circuit comprises a diode in parallel with a resistor, and a capacitor connected in series with this parallel connection.

36. A PWM controller, comprising:

an AC voltage generator;

a control circuit incorporating at least one rectifier;

an electric load connected between said generator and said rectifier;

first and second monodirectional switches connected to the electric load in parallel; and

a driving circuit for said monodirectional switches connected to said electric load so as to detect a line current and to drive said monodirectional switches in opposition with respect to said PWM pulses, wherein said driving circuit comprises;

a first NOR logic gate inserted between said generator and a first terminal of said electric load and connected to a first pair of sensing resistors, wherein said resistors are in turn inserted between said generator and said first terminal of said electric load; and

a second NOR logic gate inserted between said rectifier and a second terminal of said electric load and connected to a second pair of sensing resistors, wherein said second pair of resistors is in turn inserted between said rectifier and said second terminal of said electric load, said sensing resistors detecting a line current in order to supply said NOR logic gates and, through such gates, to drive said monodirectional switches.

37. The PWM controller according to claim 36 wherein said NOR logic gates comprise respective pairs of bipolar transistors inserted, in parallel to each other, between a first and a second voltage reference and having base terminals connected to said sensing resistors.

38. The PWM controller according to claim 37 wherein said bipolar transistors have common collector terminals to form respective drive circuit node for said monodirectional switches.

39. An electronic device, comprising:

a universal motor operating with an alternating current;

an AC voltage generator connected to one terminal of said motor;

a PWM controller incorporating at least one rectifier and connected to another terminal of said motor, said PWM controller further comprising first and second monodirectional switches connected to the motor in parallel, wherein said controller has a circuit leg connected in parallel to the output of the rectifier and includes a power transistor supplied by a PWM signal; and

a snubber circuit in parallel with said circuit leg.

40. The electronic device according to claim 39 wherein said snubber circuit comprises a diode in parallel with a resistor, and a capacitor connected in series with this parallel connection.