Power supply for electrostatic devices

• US 5,920,474 A
• Filed: 05/19/1997
• Issued: 07/06/1999
• Est. Priority Date: 02/14/1995
• Status: Expired due to Fees

• Current Assignee: Powerspan Corp.
• Original Assignee: ZERO Emissions Technology Incorporated
• Inventors: Neister, S. Edward, Johnson, Nathaniel M.
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US08/858,904
• Time in Patent Office: 778 Days
• Field of Search: 363/67, 363/68, 363/84, 363/85, 363/125, 363/126, 363/128, 363/129, 363/135, 363/136
• US Class Current: 363/126
• CPC Class Codes: B03C 3/66 Applications of electricity supply techniques
• CPC Class Codes: B03C 3/68 Control systems therefor electricity supply or control systems for cleaning the electrodes B03C3/746, B03C3/763
• CPC Class Codes: H02M 7/10 arranged for operation in series, e.g. for multiplication of voltage
• CPC Class Codes: H02M 7/155 using semiconductor devices only

Abstract

A power supply method particularly adapted for use with an electrostatic particulate collection device to provide substantially ripple-free DC power for improved operation. The power supply is adapted to receive three-phase AC power and to transform the AC power into high voltage DC power having a minimum of voltage ripple in the output. The power supply includes a multi-phase transformer having three primary windings, each of the primary windings having associated with it a pair of secondary windings. The primary windings can be either delta connected or wye connected. One of each of the secondary windings associated with one of the respective primary windings are connected together in a delta connection arrangement, and the remaining secondary windings are connected in a wye connection arrangement. Because the respective AC voltage outputs of each of the secondary windings is out of phase with the AC voltage outputs of the other secondary windings, the resultant combined DC output voltage, after the DC voltages have been rectified in a three-phase full-wave bridge rectifier stack, produces minimum ripple voltage and current, without requiring additional, more expensive, and less reliable components.

Claims

1. A method for providing a substantially ripple-free DC voltage to an electrostatic particulate collection device from a source of three-phase AC power, said method comprising:

a) applying three-phase AC power from a three-phase AC power source to primary windings of a transformer having three primary windings connected in a delta connection arrangement;

b) arranging three pairs of secondary windings in electromagnetically coupled relationship with respective ones of the primary windings, wherein respective ones of the windings of each pair of secondary windings are connected in a wye connection arrangement to provide a plurality of first output voltages and the remaining ones of each pair of the respective secondary windings are connected in a delta connection arrangement to provide a plurality of second output voltages;

c) coupling the first three output voltages with a first full wave rectifier stack to provide a first rectified output voltage;

d) coupling the second three output voltages with a second full wave rectifier stack to provide a second rectified output voltage;

e) coupling the first and second rectifier stacks in series to provide a substantially ripple-free DC output voltage; and

f) coupling the DC output voltage with an electrostatic particulate collection device electrode.

2. A method in accordance with claim 1 including the step of placing the secondary coils in side-by-side relationship.

5. A method in accordance with claim 1 wherein the rectifier stack is a half wave rectifier stack.

6. A method in accordance with claim 1 further comprising the step of providing a three-phase solid state switch electrically connected between the three-phase AC power source and the transformer.

7. A method in accordance with claim 6 further comprising the step of controlling the AC power to the transformer by providing a sine wave variable voltage controller electrically connected between the switch and the transformer.

8. A method in accordance with claim 7 further comprising the step of providing at least one current limiting reactor electrically connected between the switch and the transformer.

9. A method in accordance with claim 7 further comprising the step of providing at least one current limiting reactor electrically connected between the switch and sine wave variable voltage controller.

10. A method in accordance with claim 7 further comprising the step of controlling the switch and voltage controller by providing a microprocessor-based controller electrically connected between the rectifier stack and each of the switch and voltage controller.

11. A method in accordance with claim 1 further comprising the step of filtering power by providing a secondary impedance element electrically connected between the rectifier stack and the electrode.

12. A method in accordance with claim 1 further comprising the step of providing three reverse-blocking, triode-type P-type gate thyristors, each one electrically connected to a respective one of the three primary windings.

3. A method for providing a substantially ripple-free DC voltage to an electrostatic particulate collection device from a source of three-phase AC power, said method comprising:

a) applying three-phase AC power from a three-phase AC power source to primary windings of a transformer having three primary windings connected in a wye connection arrangement;

b) arranging three pairs of secondary windings in electromagnetically coupled relationship with respective ones of the primary windings, wherein respective ones of the windings of each pair of secondary windings are connected in a wye connection arrangement to provide a plurality of first output voltages and the remaining ones of each pair of the respective secondary windings are connected in a delta connection arrangement to provide a plurality of second output voltages;

c) coupling the first three output voltages with a first full-wave rectifier stack to provide a first rectified output voltage;

d) coupling the second three output voltages with a second full wave rectifier stack to provide a second rectified output voltage;

e) coupling the first and second rectifier stacks in series to provide a substantially ripple-free DC output voltage; and

f) coupling the DC output voltage with an electrostatic particulate collection device electrode.

4. A method in accordance with claim 3 including the step of placing the secondary coils in a side-by-side relationship.

13. A method in accordance with claim 3 wherein the rectifier stack is a half wave rectifier stack.

14. A method in accordance with claim 3 further comprising the step of providing a three-phase solid state switch electrically connected between the three phase AC power source and the transformer.

15. A method in accordance with claim 14 further comprising the step of controlling the AC power to the transformer by providing a sine wave variable voltage controller electrically connected between the switch and the transformer.

16. A method in accordance with claim 15 further comprising the step of providing at least one current limiting reactor electrically connected between the switch and the transformer.

17. A method in accordance with claim 15 further comprising the step of providing at least one current limiting reactor electrically connected between the switch and sine wave variable voltage controller.

18. A method in accordance with claim 15 further comprising the step of controlling the switch and voltage controller by providing a microprocessor-based controller electrically connected between the rectifier stack and each of the switch and voltage controller.

19. A method in accordance with claim 3 further comprising the step of filtering power by providing a secondary impedance element electrically connected between the rectifier stack and the electrode.