Energy saving power control system

• US 6,191,563 B1
• Filed: 12/21/1999
• Issued: 02/20/2001
• Est. Priority Date: 11/22/1993
• Status: Expired due to Fees

• Current Assignee: Global Lighting Solutions LLC
• Original Assignee: Ultrawatt.com
• Inventors: Bangerter, Fred F.
• Primary Examiner(s): HAN, YOUNGHUIE JESSICA
• Application Number:
  US09/468,232
• Time in Patent Office: 427 Days
• Field of Search: 323/209, 323/211, 323/239, 323/241, 323/299, 323/300, 323/301, 323/319, 323/320, 323/322, 323/325, 323/326, 323/349, 323/351, 323/352, 315/291, 315/307
• US Class Current: 323/211
• CPC Class Codes: G05F 1/45 being controlled rectifiers in series with the load
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 1/12 Arrangements for reducing harmonics from ac input or output
• CPC Class Codes: H02M 3/1555 for the generation of a regulated current to a load whose impedance is substantially inductive
• CPC Class Codes: H02M 5/2573 with control circuit
• CPC Class Codes: H02M 5/2576 with digital control
• CPC Class Codes: H05B 41/3924 by phase control, e.g. using a triac H05B41/3922 takes precedence
• CPC Class Codes: H05B 41/3927 by pulse width modulation H05B41/3922 takes precedence
• CPC Class Codes: H05B 41/40 discontinuously

Abstract

Apparatus and methods for AC power regulation primarily intended for inductive loads (e.g., fluorescent lights, motors, etc.) which provide substantial reduction in power consumption while also providing a leading power factor, reduced harmonic distortion, reduced crest factor and reduced noise. The system is self-adjusting for a wide range of loads and can reduce power consumption by 25 percent in lighting loads while producing minimal reduction in light output. The system utilizes a Triac and parallel capacitor bank in series with the load. The Triac is turned on in response to a near-zero differential voltage measured across the Triac and is turned off near the peak of each AC half cycle by shunting current around the Triac. The capacitor absorbs the inductive turn-off voltage spike caused by the collapsing magnetic field in the ballast at the instant of Triac turn-off. This energy, in turn, provides longer on-period for the lamp, thereby permitting more light and increased operating efficiency. The turn-off time is adjusted to regulate power at a reduced level responsive to line voltage, load current and load power-sense signals.

Claims

1. A power regulation apparatus for an electrical system having an AC power source and a load having a combination of resistive and reactive impedances, the apparatus comprising:

switching circuitry coupled to the AC power source and to the load; and

control circuitry operable to control the switching circuitry in a power savings mode to modify a waveform applied to the load, said load waveform being characterized by substantially the same peak value of an AC power source waveform and a substantially lower RMS value than the AC power source waveform.

2. The power regulation apparatus of claim 1 wherein the switching circuitry provides a leading power factor.

3. The power regulation apparatus of claim 1 wherein the switching circuitry modifies the load waveform to be a quisi-sinusoidal waveform.

4. The power regulation apparatus of claim 3 wherein the quasi-sinusoidal waveform is characterized by a line frequency substantially the same as a line frequency of the AC power source waveform and by an exponential decay following a peak of the quasi-sinusoidal waveform.

5. The power regulation apparatus of claim 1 wherein the switching circuitry is operable to modify the load waveform for loads comprising different load impedances.

6. The power regulation apparatus of claim 1 wherein the switching circuitry further comprises:

a controllable switch in series between the AC power source and the load; and

wherein the control circuitry comprises;

first control circuitry that causes the controllable switch to enter a conduction state at a selected turn-on time;

second control circuitry that causes the controllable switch to enter a non-conductive state at a selected turn-off time; and

third control circuitry that selects the turn-on time and turn-off time based on a reduced power level.

7. The power regulation apparatus of claim 1 further comprising a capacitance connected in series between the AC power source and the load.

8. The power regulation apparatus of claim 1 wherein an average power of said load waveform comprises about a 25 percent reduction from an average power of the AC power source waveform, the load waveform comprising a same number of zero crossings as the AC power source waveform.

9. A power regulation apparatus for fluorescent and other ballasted lighting systems having an AC power source and a load having a combination of resistive and reactive impedances, the apparatus comprising:

switching circuitry coupled to the AC power source and to the load; and

control circuitry operable to control the switching circuitry in a power savings mode to modify a waveform applied to the load, said load waveform having a substantially lower RMS value than the AC power source waveform while maintaining a peak value sufficient to minimize light intensity loss.

10. The power regulation apparatus of claim 9 wherein the switching circuitry provides a leading power factor.

11. The power regulation apparatus of claim 9 wherein the switching circuitry modifies the load waveform to be a quasi-sinusoidal waveform.

12. The power regulation apparatus of claim 9 wherein the switching circuitry further comprises:

a controllable switch in series between the AC power source and the load; and

the control circuitry comprises;

first control circuitry that causes the controllable switch to enter a conduction state at a selected turn-on time;

second control circuitry that causes the controllable switch to enter a non-conductive state at a selected turn-off time; and

third control circuitry that selects the turn-on time and turn-off time based on a reduced power level.

13. The power regulation apparatus of claim 9 further comprising a capacitance connected in series between the AC power source and the load.

14. A method for providing power regulation for a system having an AC power source and a load having a combination of resistive and reactive impedances, the method comprising the steps of:

(a) providing a source waveform;

(b) modifying the source waveform in a power-savings mode, the modified waveform characterized by a substantially same peak value of the source waveform and a substantially lower RMS value than the source waveform; and

(c) applying the modified waveform to the load.

15. An improvement in a load waveform provided by a power regulation apparatus in a power-savings mode for an electrical system having an AC power source and a load having a combination of a resistive and reactive impedances, the improvement in the load waveform comprising:

said waveform being measurably modified to have substantially the same peak value of an AC power source waveform and a substantially lower RMS value than the AC power source waveform;

wherein the power regulation apparatus comprises a switch and a switch controller, the load waveform modification responsive to the switch and the switch responsive to the switch controller.

16. An AC power regulation system for controlling load power to a load, said power regulation system having an input for coupling to an AC power source and having an output for coupling to the load, said power regulation system comprising:

a controllable switch coupled in series between the input and the output;

circuitry for supplying capacitance coupled in parallel with the controllable switch, the capacitance being proportional to the line current and operable to pass the line current during a substantial portion of a half cycle of the line current;

circuitry for turning-on the controllable switch to a conducting state;

circuitry for turning-off the controllable switch to a non-conducting state; and

switch control circuitry for generating control signals to control said circuitry for turning-on and said circuitry for turning-off such that the controllable switch is turned on to a conducting state at a selected turn-on time, and is turned off to a non-conducting state at a selected turn-off time prior to a line current zero-crossing point, said turn-off time being selected by said switch control circuitry in response to a reference signal;

wherein the switch control circuitry is operable to modify the load waveform for loads comprising different load impedances.

17. The system of claim 16 wherein the capacitance comprises at least 100 uF.

18. The system of claim 16 wherein the capacitance is sufficiently large so that current conduction avoids a ringing effect.