Methods and systems for controlling electrical power to DC loads

• US 8,604,709 B2
• Filed: 05/13/2010
• Issued: 12/10/2013
• Est. Priority Date: 07/31/2007
• Status: Active Grant

• Current Assignee: Greenvision Group Technologies Corporation
• Original Assignee: LSI Industries Incorporated
• Inventors: Jalbout, Bassam D., Wong, Brian
• Primary Examiner(s): Ismail, Shawki
• Assistant Examiner(s): LO, CHRISTOPHER KWOK YEUNG
• Application Number:
  US12/779,179
• Publication Number:
  US 20100244929A1
• Time in Patent Office: 1,307 Days
• Field of Search: 315/291, 315/307, 315/308, 315/209.R, 315/119, 315/121, 315/122, 315/123, 315125-128, 315/185.R, 315/186, 315/192, 315/193, 315/185.S, 315/210, 315224-226, 315/294, 315/297, 315299-302, 315310-311, 315/362
• US Class Current: 315/291
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: H02M 3/157 with digital control
• CPC Class Codes: H02M 3/33515 with digital control
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

Fixed Frequency, Fixed Duration power controls methods and systems are described for application of power to electrical loads. FFFD techniques according to the present disclosure utilize power train pulses with fixed-frequency fixed-duration pulses to control power applied to a load. The load can be any type of DC load. FFFD techniques allows for controlled variation of the fixed length of the ON pulse, the Fixed length of the OFF or recovery period, the total time period for one cycle, and/or the number of pulses in that time period. Applications to electric motors, electric lighting, and electric heating are described. Related circuits are also described.

Claims

1. A method of using pulses of fixed duration and fixed frequency for power control of electrical loads, the method comprising:

with a processing system, providing a timing signal to a circuit, wherein the timing signal includes an ON state and an OFF state;

determining a desired power level for an electrical load in the circuit;

based on the timing signal, generating a control signal including a sequence of control pulses of fixed duration and fixed frequency within the timing signal and corresponding to the desired power level; and

supplying the control signal to an input of a current switch connected to the electrical load, in the circuit, to place the switch in one of an ON state during each pulse and an OFF state after each pulse to cause current to flow from a first potential to a second potential through the electrical load during the ON state;

wherein the circuit has an initial condition before flow of current through the current switch and the period time between each of the pulses of the timing cycle is longer than the period of time for the circuit to return to the initial condition after a pulse of the timing cycle.

2. The method of claim 1, further comprising varying the number of pulses within a repeating time cycle.

3. The method of claim 1, wherein the electrical load comprises one or more DC electric motors.

4. The method of claim 1, wherein providing a timing signal comprises using software using decrementing or incrementing counters to control the time periods of the control pulses.

5. The method of claim 3, further comprising controlling the movement of the one or more DC electrical motors.

6. The method of claim 1, wherein generating a control signal comprises using analog pulse shaping circuits.

7. The method of claim 6, further comprising controlling power applied to one or more electric motors.

8. The method of claim 1, further comprising controlling power applied to one or more electric light sources.

9. The method of claim 8, further comprising controlling the intensity of the optical output of the one or more light sources by varying the number of pulses within a repeating time cycle.

10. The method of claim 1, further comprising controlling power applied to one or more heating devices.

11. The method of claim 10, further comprising controlling a heat output by varying the number of pulses within a repeating time cycle.

12. The method of claim 1, further comprising controlling power applied to one or more switching power supplies, by varying the number of pulses within a repeating time cycle.

13. A FFFD power control circuit comprising:

a first power potential;

a second power potential;

an electrical load; and

a current switch connected to the electrical load and including an input to receive a current switch control signal to place the switch in one of an ON state and an OFF state including a timing cycle with a series of pulses of fixed duration and fixed frequency within the timing cycle to cause current to flow from the first potential to the second potential through the load during the ON state to cause the load to receive power over the timing cycle;

wherein the circuit has an initial condition before flow of current through the current switch and the period time between each of the pulses of the timing cycle is longer than the period of time for the circuit to return to the initial condition after a pulse of the timing cycle.

14. The circuit of claim 13, wherein the load is a light emitting diode (LED).

15. The circuit of claim 13, wherein the load comprises an array of light emitting diodes.

16. The circuit of claim 13, wherein the load comprises an electric circuit of a DC motor.

17. The circuit of claim 16, wherein the DC motor is a brushless DC motor.

18. The circuit of claim 13, wherein the load comprises an electric circuit of an AC motor.

19. The circuit of claim 14, wherein the number of pulses in a timing cycle varies from zero to a maximum number corresponding to an intensity level of the LED from zero to a maximum intensity.

20. The circuit of claim 13, wherein the load comprises a heating element.

21. The circuit of claim 20, wherein the number of pulses in a timing cycle varies from zero to a maximum number corresponding to a heat output level of the heating element from zero to a maximum heat output.

22. The circuit of claim 13, further comprising a processing device to generate the current switch control signal supplied to the current switch and to time the start and end of each pulse within the timing cycle.

23. The circuit of claim 13, further comprising a second current switch connected to the load.

24. The circuit of claim 23, further comprising a shunt resistor connected to the first or second current switches and the first or second power potentials.

25. The circuit of claim 23, further comprising a shunt diode connected to the first or second current switches and the first or second power potentials.