Electronic control circuits, electronically commutated motor systems, switching regulator power supplies, and methods

• US 4,859,921 A
• Filed: 03/10/1988
• Issued: 08/22/1989
• Est. Priority Date: 03/10/1988
• Status: Expired due to Term

• Current Assignee: Regal Beloit Electronic Motors Incorporated
• Original Assignee: General Electric Company
• Inventors: Archer, William R.
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US07/167,574
• Time in Patent Office: 530 Days
• Field of Search: 318/138, 318/254, 318/439, 318/599
• US Class Current: 318/599
• CPC Class Codes: H02M 7/5387 in a bridge configuration
• CPC Class Codes: H02P 6/085 in a bridge configuration
• CPC Class Codes: H03K 17/567 Circuits characterised by the use of more than one type of semiconductor device, e.g. BIMOS, composite devices such as IGBT

Abstract

Electronic control circuit for use with electrical load powering apparatus having a load connection, a high voltage supply connection and a common, and with an electronic switch to switch the high voltage supply connection to the load connection. The electronic switch has an input and is responsive to a voltage difference between the input and the load connection. The load connection is subject to high voltage excursions relative to the common due to the switching. The electronic control circuit includes a transformer having a primary winding and a secondary winding for providing at least one pulse output from the secondary winding, the transformer having an inherent interwinding capacitance between the primary winding and the secondary winding. A circuit connected to the secondary winding couples the pulse output from the secondary winding between the input of the electronic means and the load connection when the pulse output is present. A high voltage excursion on the load connection charges the inherent interwinding capacitance to a high voltage level when the pulse output is present. The electronic control circuit further includes circuitry for bypassing the high voltage level on the inherent interwinding capacitance of the transformer to the load connection when the pulse output and each high voltage excursion cease. An electronically commutated motor system, a switching regulator power supply and methods of operation are also disclosed.

Claims

1. For use with electrical load powering apparatus having a load connection, a high voltage supply connection and a common, and with electronic means for switching the high voltage supply connection to the load connection, the electronic means having an input and being responsive to a voltage difference between the input and the load connection, the load connection being subject to high voltage excursions relative to the common due to the switching, an electronic control circuit comprising:

a transformer having a primary winding and a secondary winding for providing at least one pulse output from said secondary winding, said transformer having an inherent interwinding capacitance between said primary winding and said secondary winding;

means connected to said secondary winding for coupling the pulse output from said secondary winding between the input of the electronic means and the load connection when the pulse output is present, a high voltage excursion on the load connection charging the inherent interwinding capacitance to a high voltage level when the pulse output is present; and

means for bypassing the high voltage level on the inherent interwinding capacitance of said transformer to the load connection when the pulse output and each high voltage excursion cease, including active control means having an input and first and second control leads and means for providing a resistive path substantially free of inductance between the input of said active control means and the input of the electronic means, said active control means thereby bypassing current from the input of the electronic means to the load connection through the first and second control leads and the high voltage level being prevented from actuating the electronic means when each high voltage excursion ceases.

2. An electronic control circuit as set forth in claim 1 wherein said means for providing a resistive path includes a resistive network and said means for coupling includes full wave bridge rectification means connected across said secondary winding, said full wave bridge rectification means having a first output connected directly to said input of said active control means and a second output connected to said resistive network, said active control means having its input and at least one of its control leads directly connected to said resistive network, said resistive network having a further connection for the input of the electronic means.

3. An electronic control circuit as set forth in claim 1 wherein said secondary winding is capacitively connected to said input of said active control means and said means for coupling includes means connected elsewhere from said secondary winding to said input of said active control means for unidirectional conduction in a direction opposite to a direction of discharge of current from the inherent interwinding capacitance.

4. An electronic control circuit as set forth in claim 1 wherein said input of said active control means is also separately connected to said secondary winding to sense the high voltage level of the inherent interwinding capacitance.

5. An electronic control circuit as set forth in claim 1 further comprising means responsive to the pulse output of said secondary winding for temporarily preventing operation of said means for bypassing.

6. An electronic control circuit as set forth in claim 1 wherein said active control means is only responsive to a predetermined voltage polarity between its input and said first control lead, and said secondary winding is connected between said input and said second control lead of said active control means so that the pulse output is prevented from actuating said active control means and is coupled instead to the electronic means.

7. An electronic control circuit as set forth in claim 1 wherein said active control means is only responsive to a predetermined voltage polarity between its input and said first control lead and further comprising unidirectional conduction means connected between the load connection and the input of said active control means and poled to develop a voltage opposite to the predetermined voltage polarity when a high voltage excursion occurs.

8. An electronic control circuit as set forth in claim 1 wherein said means for providing a resistive path includes a resistive network and said means for coupling includes a diode network connected between said secondary winding and said resistive network, said active control means having one of its control leads connected both to the load connection and to said diode network.

9. An electronic control circuit as set forth in claim 1 wherein said active control means includes a transistor having an emitter connected to the load connection, a collector resistively connected to the input of the electronic means, and a base as the input of said active control means connected also to sense the high voltage level on the inherent interwinding capacitance.

10. An electronic control circuit as set forth in claim 9 wherein said transistor is an NPN transistor.

11. An electronic control circuit as set forth in claim 1 wherein said secondary winding is directly connected to the input of said active control means and said means for coupling includes means connected elsewhere to said secondary winding for half wave rectifying the pulse output for the input of the electronic means.

12. An electronic control circuit as set forth in claim 1 wherein said means for coupling includes means for half wave rectifying and filtering the pulse output of said secondary winding.

13. An electronic control circuit as set forth in claim 1 wherein said means for coupling includes means for full wave rectifying the pulse output of said secondary winding.

14. An electronic control circuit as set forth in claim 1 wherein said secondary winding of said transformer has two ends and said means for coupling includes a pair of identically poled diodes respectively connected to each end of said secondary winding.

15. An electronic control circuit as set forth in claim 14 wherein said secondary winding has a center tap connected to said input of said active control means, and said pair of diodes are connected to said means for providing a resistive path.

16. An electronic control circuit as set forth in claim 14 wherein said pair of diodes are connected together and to the input of said active control means, and said secondary winding has a center tap connected to said means for providing a resistive path.

17. An electronic control circuit as set forth in claim 1 wherein said means for coupling includes means for charging the inherent interwinding capacitance from the load connection when the pulse output occurs.

18. An electronic control circuit as set forth in claim 17 wherein said means for charging includes unidirectional conduction means connected for conduction from the load connection to said transformer.

19. An electronic control circuit as set forth in claim 1 further comprising a pair of logic gates connected to opposite ends of said primary winding of said transformer.

20. An electronic control circuit as set forth in claim 19 wherein said pair of logic gates are CMOS with outputs directly connected to said primary winding.

21. An electronic control circuit as set forth in claim 1 further comprising clock circuit means for producing pulses having a repetition rate and means for switching the pulses at a switching rate less than the repetition rate to said primary winding.

22. An electronic control circuit as set forth in claim 21 wherein said means for switching is responsive to a switching waveform input thereto and wherein said means for coupling includes full wave rectification means for recovering said switching waveform substantially free of said pulses from said clock circuit means.

23. An electronic control circuit as set forth in claim 22 wherein said means for switching includes a pair of logic gates connected to opposite ends of said primary winding, the logic gates each having an input for said switching waveform and a second input connected to said clock circuit means for alternately enabling said pair of logic gates.

24. An electronic control circuit for use in electrical load powering apparatus having a load connection, a high voltage supply connection and a common, the electronic control circuit comprising:

a solid state power switching device having a high impedance input and control terminals connected between the high voltage supply connection and the load connection, the high impedance input having an inherent input capacitance, the load connection being subject to high voltage extrusions relative to the common due to switching;

transformer means having a primary winding and a secondary winding and an inherent interwinding capacitance therebetween;

active control means having an input and first and second control leads;

a diode network connected to said secondary winding, for providing output pulses when energized by said secondary winding; and

a resistive network connected between said diode network and said high impedance input of the solid state power switching device, said active control means having its input connected to both said diode network and to said resistive network and its first control lead connected both to the load connection and to said diode network and its second control lead connected to said resistive network, so that, when one of the output pulses from said diode network ceases, said resistive network provides an essentially delay-free direct path from said high impedance input of said solid state power switching device to said active control means and the inherent input capacitance is discharged through said active control means and so that when each high voltage excursion ceases the interwinding capacitance is bypassed through said active control means, whereby the high impedance input of said solid state power switching device is bypassed.

25. An electronic control circuit as set forth in claim 24 further comprising means for energizing said primary winding of said transformer means with high frequency bi-directional pulses initiated in accordance with low frequency control pulses, wherein said diode network includes means connected to said secondary winding for full wave rectifying the high frequency bidirectional pulses to recover the low frequency control pulses as the output pulses.

26. An electronic control circuit as set forth in claim 24 wherein said diode network includes diode means for unidirectional conduction of current between the load connection and said secondary winding to charge the interwinding capacitance when one of the high voltage excursions occurs.

27. An electronic control circuit as set forth in claim 26 wherein said active control means has its input and its first control lead connected across said diode means for unidirectional conduction of current to prevent operation of said active control means when a high voltage excursion occurs.

28. An electronic control circuit as set forth in claim 24 wherein said diode network includes four diodes connected as a bridge rectifier across said secondary winding and having a first output connected directly to said input of said active control means and a second output connected to said resistive network.

29. An electronic control circuit as set forth in claim 24 wherein said active control means is only responsive to a predetermined voltage polarity between its input and said first control lead, and said secondary winding is coupled across said input and said second control lead of said active control means so that the pulse output is prevented from actuating said active control means and is coupled instead to said solid state power switching device.

30. An electronic control circuit as set forth in claim 24 wherein said secondary winding of said transformer means has a center tap connected to said resistive network and said secondary winding further has two ends, and said diode network includes a pair of identically poled diodes respectively connected from the two ends of said secondary winding to said input of said active control means.

31. An electronic control circuit as set forth in claim 24 further comprising clock circuit means for producing pulses having a repetition rate and means for switching the pulses at a switching rate less than the repetition rate to said primary winding in accordance with a switching waveform.

32. An electronic control circuit as set forth in claim 31 wherein said means for switching includes a pair of CMOS logic gates with outputs directly connected to opposite ends of said primary winding, said CMOS logic gates each having an input for said switching waveform and a second input connected to said clock circuit means for alternately enabling said pair of logic gates.

33. An electronic control circuit for use in electrical load powering apparatus having a load connection, a high voltage supply connection and a common, the electronic control circuit comprising:

a switching device having a high impedance input with an inherent input capacitance, said switching device also having control terminals connected between the high voltage supply connection and the load connection;

transformer means having a primary winding and a secondary winding and an inherent interwinding capacitance therebetween, said secondary winding producing an output when said primary winding is energized, said switching device being responsive to the output from said secondary winding to switch on so that the load connection is subject to a high voltage excursion relative to the common when said switching device switches on;

first and second means connected at a junction and poled serially for unidirectional conduction through either or both of said first and second means, said first means connected to the load connection and said second means connected to said secondary winding to charge the inherent interwinding capacitance when a high voltage excursion occurs at the load connection;

active control means having a first control lead connected to the load connection, a second control lead connected to the junction of said first and second means for unidirectional conduction and a third control lead connected to the high impedance input of said switching device; and

means for providing an essentially delay-free path from the high impedance input of said switching device to said active control means at said second control lead so that when an output from said secondary winding ceases the inherent input capacitance of said switching device is discharged through at least two of said control leads of said active control means, turning said switching device off, and when the high voltage excursion ceases the inherent interwinding capacitance is thereby also bypassed through said active control means.

34. An electronic control circuit as set forth in claim 33 further comprising third means for unidirectional conduction connected between said second control lead of said active control means and said secondary winding in a direction opposite to a direction of discharge of the inherent interwinding capacitance.

35. An electronic control circuit as set forth in claim 34 wherein said secondary winding has a tap directly connected to said means for providing an essentially delay-free path at a point electrically distinct from said second control lead of said active control means.

36. An electronic control circuit as set forth in claim 33 wherein said means for providing an essentially delay-free path includes a passive electrical network.

37. An electronic control circuit as set forth in claim 36 further comprising third and fourth means for unidirectional conduction connected across said secondary winding, and also connected to each other at a junction connected to said passive electrical network.

38. An electronic control circuit as set forth in claim 37 further comprising fifth means for unidirectional conduction connected between said second control lead of said active control means and said secondary winding in a direction opposite to a direction of discharge of said inherent interwinding capacitance.

39. An electronic control circuit as set forth in claim 33 wherein said secondary winding is capacitively connected to said second control lead of said active control means.

40. An electronic control circuit as set forth in claim 33 further comprising clock circuit means for producing pulses having a repetition rate and means for switching the pulses at a switching rate less than the repetition rate to said primary winding in accordance with a switching waveform.

41. An electronic control circuit as set forth in claim 40 wherein said means for switching the pulses includes a pair of CMOS logic gates with outputs directly connected to opposite ends of said primary winding, said CMOS logic gates each having an input for said switching waveform and a second input connected to said clock circuit means for alternately enabling said pair of logic gates.

42. For use in electrical load powering apparatus having a load connection, a high voltage supply connection and a common, and including electronic means for switching the high voltage supply connection to the load connection, the electronic means having an input and being responsive to a voltage difference between the input and the load connection, the load connection being subject to high voltage excursions relative to the common due to the switching, an electronic control circuit comprising:

transformer means having a primary winding and a secondary winding for providing at least one pulse output from said secondary winding, said transformer means having an inherent interwinding capacitance between said primary winding and said secondary winding;

means connected to said secondary winding for coupling the pulse output from said secondary winding between the input of the electronic means and the load connection when the pulse output is present, a high voltage excursion on the load connection charging the inherent interwinding capacitance to a high voltage level when the pulse output is present; and

means for bypassing the high voltage level on the inherent interwinding capacitance of said transformer means to the load connection when the pulse output and the high voltage excursion cease, to prevent the high voltage level from actuating the electronic means, said means for bypassing having an input to which said secondary winding is capacitively connected, and said means for coupling including means, connected elsewhere to said secondary winding from said input of said means for bypassing, for unidirectional conduction in a direction opposite to a direction of discharge of current from the inherent interwinding capacitance.

43. An electronic control circuit as set forth in claim 42 wherein said input of said means for bypassing is also resistively connected to said secondary winding to sense the high voltage level on the inherent interwinding capacitance.

44. An electronic control circuit as set forth in claim 42 further comprising means responsive to each high voltage excursion for temporarily disabling said means for bypassing.

45. An electronic control circuit as set forth in claim 42 further comprising clock circuit means for producing pulses having a repetition rate and means for switching the pulses at a switching rate less than the repetition rate to said primary winding in accordance with a switching waveform.

46. An electronic control circuit as set forth in claim 45 wherein said means for switching the pulses includes a pair of CMOS logic gates with outputs directly connected to opposite ends of sad primary winding, said CMOS logic gates each having an input for the switching waveform and a second input connected to said clock circuit means for alternately enabling said pair of logic gates.

47. For use in electrical load powering apparatus having a load connection, a high voltage supply connection and a common, and including electronic means for switching the high voltage supply connection to the load connection, the electronic means having an input and being responsive to a voltage difference between the input and the load connection, the load connection being subject to high voltage excursions relative to the common due to the switching, an electronic control circuit comprising:

transformer means having a primary winding and a secondary winding for providing at least one pulse output from said secondary winding, said transformer means having an inherent interwinding capacitance between said primary winding and said secondary winding;

a resistive network having first, second and third connections;

full wave bridge rectification means connected across said secondary winding, said full wave bridge rectification means having an output connection to the first connection of said resistive network, the second connection of said resistive network coupling the pulse output to the input of the electronic means to provide the voltage difference when the pulse output is present, a high voltage excursion on the load connection charging the inherent interwinding capacitance through said full wave bridge rectification means to a high voltage level when the pulse output is present; and

means for bypassing the high voltage level on the inherent interwinding capacitance of said transformer means to the load connection when the pulse output and each high voltage excursion cease, to prevent the high voltage level from actuating the electronic means for switching, said means for bypassing having an input directly connected to said full wave bridge rectification means and further having a first control lead connected to said third connection of said resistive network and a second control lead directly connected to the load connection, whereby the input of the electronic means is bypassed through said resistive network to the load connection when each high voltage excursion ceases.

48. An electronic control circuit as set forth in claim 47 wherein said means for bypassing is only responsive to a predetermined voltage polarity between its input and said second control lead and the pulse output is thereby prevented from actuating said means for bypassing and is coupled instead to the electronic means.

49. An electronic control circuit as set forth in claim 47 wherein said means for bypassing is only responsive to a predetermined voltage polarity between its input and said second control lead and further comprising unidirectional conduction means connected between the load connection and the input of said means for bypassing and poled to develop a voltage opposite to the predetermined voltage polarity when a high voltage excursion occurs.

50. An electronic control circuit as set forth in claim 47 further comprising means responsive to each high voltage excursion for temporarily disabling said means for bypassing.

51. An electronic control circuit as set forth in claim 47 further comprising clock circuit means for producing pulses having a repetition rate and means for switching the pulses at a switching rate less than the repetition rate to said primary winding in accordance with a switching waveform.

52. An electronic control circuit as set forth in claim 47 wherein said means for switching the pulses includes a pair of CMOS logic gates with outputs directly connected to opposite ends of said primary winding, said CMOS logic gates each having an input for the switching waveform and a second input connected to said clock circuit means for alternately enabling said pair of logic gates.

53. An electronic control circuit for use in electrical load powering apparatus having a load connection, a high voltage supply connection and a common, the electronic control circuit comprising:

a solid state power switching device having a high impedance input and control terminals connected between the high voltage supply connection and the load connection;

a transformer having a primary winding and a secondary winding for providing at least one pulse output from said secondary winding, said transformer having an inherent interwinding capacitance between said primary winding and said secondary winding;

means connected to said secondary winding for coupling the pulse output from said secondary winding between said high impedance input of said solid state power switching device and the load connection when the pulse output is present, a high voltage excursion on the load connection charging the inherent interwinding capacitance to a high voltage level when the pulse output is present; and

means for bypassing the high voltage level on the inherent interwinding capacitance of said transformer to the load connection when the pulse output and each high voltage excursion cease, including active control means having an input and first and second control leads and means for providing a resistive path substantially free of inductance between the input of said active control means and said high impedance input of said solid state power switching device, said active control means thereby bypassing current from said high impedance input of said solid state power switching device to the load connection through said first and second control leads, and the high voltage level being prevented from actuating said solid state power switching device when each high voltage excursion ceases.

54. An electronic control circuit as set forth in claim 53 further comprising a second solid state power switching device having an input and control terminals connected between the load connection and the common, and means connected to the input of said second solid state power switching device for actuating said second solid state power switching device.

55. An electronic control circuit as set forth in claim 54 wherein said means for actuating said second solid state power switching device includes a second transformer having a primary winding and a secondary winding for providing at least one pulse output, and means for coupling the pulse output from said secondary winding of said second transformer between said input of said second solid state power switching device and the common, the electronic control circuit further comprising clock circuit means for producing pulses having a repetition rate, and first and second means for switching the pulses at a switching rate less than the repetition rate to said primary windings of said first and second transformers in accordance with first and second switching waveforms respectively.

56. An electronically commutated motor system for use with electrical load powering apparatus having a high voltage supply connection and a common, the electronically commutated motor system comprising:

an electronically commutated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with said stationary assembly in selective magnetic coupling relation with said winding stages; and

means for commutating said winding stages by selectively switching said winding stages at respective terminals thereof to the high voltage supply connection in response to command pulses, including;

solid state power switching devices each having a high impedance input and control terminals connected between the high voltage supply connection and the terminals of said winding stages respectively;

transformers respectively corresponding to each of said solid state power switching devices, each of said transformers having a primary winding and a secondary winding for providing an output from said secondary winding in response to a respective one of the command pulses, and having an inherent interwinding capacitance between said primary winding and said secondary winding;

means connected to each said secondary winding for coupling the output from each said secondary winding between the high impedance input of each said solid state power switching device and the terminal of the winding stage to which the switching device is connected, a high voltage excursion on the terminal of any said winding stage charging the inherent interwinding capacitance of said corresponding transformer to a high voltage level when the output is present; and

active control means each having an input and first and second control leads and means for providing resistive paths substantially free of inductance between the input of each said active control means and the high impedance input of each of said solid state power switching devices respectively, said active control means connected to bypass the high voltage level of each inherent interwinding capacitance thus charged thereby to bypass the high voltage level from the high impedance input of the corresponding solid state power switching device to the terminal of the corresponding winding stage through the first and second control leads when each high voltage excursion ceases, the high voltage level being prevented from actuating any of said solid state power switching devices when each high voltage excursion ceases.

57. An electronically commutated motor system as set forth in claim 56 further comprising additional second solid state power switching devices each having an input and control terminals connected between the terminals of the winding stages respectively and the common, and means connected to each input of said second solid state power switching devices for actuating said second solid state power switching devices.

58. An electronically commutated motor system as set forth in claim 57 wherein said means for actuating said second solid state power switching devices includes second transformers each having a primary winding and a secondary winding for providing respective outputs, and means for coupling the outputs from said secondary windings of said second transformers between the inputs respectively of said second solid state power switching devices and the common, the system further comprising clock circuit means for producing pulses having a repetition rate, and first and second means for switching the pulses at a switching rate less than the repetition rate to said primary windings of said first and second transformers in accordance with respective ones of the command pulses.

59. An electronically commutated motor system as set forth in claim 56 further comprising position sensing means for producing electrical position signals representing the position of said rotatable means, and means for generating the command pulses in response to the electrical position signals from said position sensing means.

60. An electronically commutated motor system as set forth in claim 56 further comprising means for fluid transfer driven by said electronically commutated motor.

61. An electronically commutated motor system as set forth in claim 56 further comprising heat transfer apparatus including a condenser, an evaporator connected to said condenser, and a compressor driven by said electronically commutated motor, said compressor connected to supply a refrigerant to said condenser and to receive the refrigerant from said evaporator.

62. A switching regulator power supply for use with electrical load powering apparatus having a high voltage supply connection and a common, the switching regulator power supply comprising:

a power transformer having a first winding and an output winding;

a solid state power switching device having a high impedance input and control terminals connected between the high voltage supply connection and said first winding of said power transformer, said high impedance input having an inherent input capacitance, said first winding being subject to high voltage excursions relative to the common due to the switching;

a signal transformer having a primary winding and a secondary winding for providing at least one pulse output from said secondary winding, said signal transformer having an inherent interwinding capacitance between said primary winding and said secondary winding;

means connected to said secondary winding for coupling the pulse output from said secondary winding between said high impedance input of said solid state power switching device and said first winding of said power transformer when the pulse output is present, a high voltage excursion on said first winding charging said inherent interwinding capacitance to a high voltage level when the pulse output is present; and

means for bypassing the high voltage level on the inherent interwinding capacitance of said signal transformer to said first winding of said power transformer when the pulse output and each high voltage excursion cease, including active control means having an input and first and second control leads and means for providing a resistive path substantially free of inductance between said input of said active control means and said high impedance input of said solid state power switching device, said active control means thereby bypassing current from said high impedance input of said solid state power switching device to said first winding through said first and second control leads and the high voltage level being prevented from actuating said solid state power switching device when each high voltage excursion ceases;

means connected to said output winding of said power transformer for deriving an output voltage of the switching regulator power supply;

means for detecting a difference between the output voltage and a predetermined value to which the output voltage is to be regulated; and

means for generating a pulse width modulated series of pulses for energizing the primary winding of said signal transformer as a function of the difference so detected to reduce the difference detected.

63. A switching regulator power supply as set forth in claim 62 further comprising a second solid state power switching device having an input and control terminals connected between said first winding of said power transformer and the common and means connected to said input of said second solid state power switching device for actuating said second solid state power switching device in response to said means for generating the pulse width modulated series of pulses.

64. A switching regulator power supply as set forth in claim 63 wherein said means for actuating said second solid state power switching device includes a second signal transformer having a primary winding and a secondary winding for providing at least one pulse output, and means for coupling the pulse output from said secondary winding of said second signal transformer between said input of said second solid state power switching device and the common, the switching regulator power supply further comprising clock circuit means for producing pulses having a repetition rate, and first and second means for switching the pulses at a switching rate established by the pulse width modulated series of pulses to said primary windings of said first and second signal transformers, said repetition rate exceeding the switching rate.

65. A control method for use in electrical load powering apparatus having a load connection, a high voltage supply connection and a common, and including electronic means for switching the high voltage supply connection to the load connection, the electronic means having an input and being responsive to a voltage difference between the input and the load connection, the load connection being subject to high voltage excursions relative to the common due to the switching, the control method comprising the steps of:

producing at least one pulse output from a secondary winding of a transformer having a primary winding and a secondary winding and an inherent interwinding capacitance between the primary winding and the secondary winding;

coupling the pulse output from the secondary winding between the input of the electronic means and the load connection when the pulse output is present, a high voltage excursion on the load connection charging the inherent interwinding capacitance to a high voltage level when the pulse output is present; and

providing an electrical signal substantially free of inductive delay from the input of the electronic means to an active control means so that the active control means bypasses current from the input of the electronic means to the load connection and the high voltage level is prevented from actuating the electronic means when each high voltage excursion ceases.

66. A control method for use in electrical load powering apparatus having a load connection, a high voltage supply connection and a common, and including electronic means for switching the high voltage supply connection to the load connection, the electronic means having a high impedance input with an inherent input capacitance and the electronic means being responsive to a voltage difference between the high impedance input and the load connection, the load connection being subject to high voltage excursions relative to the common due to the switching, the control method comprising the steps of:

producing a bipolar pulse output from a transformer having a primary winding and a secondary winding and an inherent interwinding capacitance between the primary winding and the secondary winding;

processing the bipolar pulse output through a diode network to produce an electrical control signal;

resistively coupling the electrical control signal from the diode network to the high impedance input of the electronic means for switching, thereby charging its inherent input capacitance and switching on, a high voltage excursion on the load connection charging the inherent interwinding capacitance of the transformer to a high voltage level;

discharging the inherent input capacitance substantially free of inductive delay when the bipolar pulse output from the transformer ceases; and

bypassing the high voltage level on the inherent interwinding capacitance to the load connection when each high voltage excursion ceases, whereby the high impedance input of the electronic means is bypassed when each high voltage excursion ceases.

67. A method of operating an electronically commutated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages, for use with electrical load powering apparatus having a high voltage supply connection and a common, the method comprising the steps of:

commutating the winding stages by selectively switching the winding stages at respective terminals thereof to the high voltage connection with high impedance input solid state switching devices in response to pulses, each high impedance input having an inherent input capacitance;

producing the pulses rectified from transformers having a primary winding and a secondary winding and an inherent interwinding capacitance between the primary winding and the secondary winding, a high voltage excursion due to the switching on the terminal of any winding stage charging the inherent interwinding capacitance of a corresponding transformer to a high voltage level;

discharging each inherent input capacitance substantially free of inductive delay when each pulse so rectified ceases; and

bypassing each inherent interwinding capacitance thus charged to the terminal of the corresponding winding stage to avoid actuating the high impedance input of each corresponding solid state switching device when each high voltage excursion ceases.