Energy saving lighting controller

• US 6,046,549 A
• Filed: 09/29/1997
• Issued: 04/04/2000
• Est. Priority Date: 09/29/1997
• Status: Expired due to Fees

• Current Assignee: The Energy Conservatory
• Original Assignee: U.S. Energy, Inc.
• Inventors: James, Mark S.
• Primary Examiner(s): VU, DAVID HUNG
• Application Number:
  US08/940,042
• Time in Patent Office: 918 Days
• Field of Search: 315/307, 315/257, 315/205, 315/276, 315/277, 315/291, 315/360
• US Class Current: 315/291
• CPC Class Codes: G05F 1/12 wherein the variable actually regulated by the final control device is ac G05F1/625 takes precedence
• CPC Class Codes: H05B 41/40 discontinuously

Abstract

An energy saving controller system providing, from one power source, one of a plurality of different voltages to a load of electrical energy consuming devices, without power interruption to the load during transition time. The system includes a power switching circuit, a current sensing circuit and a control circuit. The power switching circuit produces, at its output port, one of the different voltages in response to receipt of a control signal of regulated magnitude. The current sensing circuit measures the power switching circuit output current and produces a measured current signal. The control circuit senses an increase in the measured current signal, which indicates an increase in current demand by the load, and outputs a control signal of regulated magnitude to the power switching circuit, initiating the voltage switching.

Claims

1. An energy saving controller system providing, from one power source having a positive terminal and a negative terminal, one of a plurality of different voltages to a load including at least one electrical energy consuming device, the system comprising:

(a) a power switching circuit, in electrical communication with the power source, for producing one of the plurality of different voltages at an output port in response to a control signal of regulated magnitude, said power switching circuit being configured to effect switching between the different voltages without power interruption to the load;

(b) a current sensing circuit, in electrical communication with the output port of the power switching circuit, for measuring current at said output port and for producing a measured current signal; and

(c) a control circuit in electrical communication with the power source, the power switching circuit, and the current sensing circuit, said control circuit for sensing an increase in the measured current signal from the power switching circuit with said increase unrelated to an increase in voltage of the power source, for outputting the control signal to the power switching circuit, and for regulating the magnitude of the control signal in response to the sensed increase in the measured current signal.

2. The energy saving controller system as recited in claim 1 wherein the power switching circuit comprises:

(a) a relay coupled to the control circuit for receiving the control signal; and

(b) a step-down transformer comprising a primary winding and a secondary winding, said secondary winding being connected in series between the positive terminal of the power source and the positive terminal of the output port, said primary winding being coupled to the power source via the relay such that the primary winding and the secondary winding have opposite polarities, thereby causing the voltage across the output port to be approximately equal to a difference between the power source voltage and the voltage across the secondary winding;

(c) wherein, upon receipt of the control signal of regulated magnitude, the relay disconnects the primary winding from the power source voltage then short-circuits the primary winding, thereby causing the secondary winding to be substantially short-circuited and the voltage across the output port to be approximately equal to the power source voltage.

3. The energy saving controller system as recited in claim 1 wherein the current sensing circuit comprises a current transformer.

4. The energy saving controller system as recited in claim 1 wherein the control circuit comprises:

(a) a differential sensing circuit for sensing an increase in the measured current signal and for producing a trigger signal thereupon; and

(b) a processing circuit, coupled to the differential sensing circuit, for producing the control signal, for regulating the magnitude of the control signal in response to receipt of said trigger signal, for controlling duration of the control signal, and for regulating sensitivity of the differential sensing circuit.

5. The energy saving controller system as recited in claim 4 wherein the differential sensing circuit comprises:

(a) a rectifier circuit for rectifying the measured current signal and producing a rectified signal;

(b) a first filter circuit, having a first time constant, coupled to the rectifier circuit, for filtering the rectified signal and producing a first filtered signal;

(c) a second filter circuit, having a second time constant different from the first time constant, coupled to the rectifier circuit, for filtering the rectified signal and producing a second filtered signal; and

(d) a differential amplifier circuit for producing the trigger signal, said differential amplifier circuit receiving the first filtered signal at a first input and the second filtered signal at a second input, the trigger signal being an amplified difference of the two filtered signals.

6. The energy saving controller system as recited in claim 4 wherein the differential sensing circuit comprises:

(a) a rectifier circuit for rectifying the measured current signal and producing a rectified signal;

(b) a first filter circuit, having a first time constant, coupled to the rectifier circuit, for filtering the rectified signal and producing a first filtered signal;

(c) a second filter circuit, having a second time constant different from the first time constant, coupled to the rectifier circuit, for filtering the rectified signal and producing a second filtered signal; and

(d) a variable gain differential amplifier circuit for producing the trigger signal, said differential amplifier circuit receiving the first filtered signal at a first input and the second filtered signal at a second input, the trigger signal being an amplified difference of the two filtered signals, the gain of said differential amplifier circuit being regulated by the processing circuit, said gain being closely related to sensitivity of the differential sensing circuit.

7. The energy saving controller system as recited in claim 4 wherein the processing circuit comprises a non-volatile memory for storing settings used in regulating the duration of the control signal and the sensitivity of the differential sensing circuit, said settings being selected from the group of user-defined settings and settings resulting from adaptive control algorithms.

8. The energy saving controller system as recited in claim 4 wherein the processing circuit comprises a microprocessor.

9. The energy saving controller system as recited in claim 1 further comprises:

(a) a visual display, in electrical communication with the control circuit, for showing status of the system; and

(b) a computer interface, in electrical communication with the control circuit, for receiving inputs from a user.

10. The energy saving controller system as recited in claim 5 wherein the first and second filter circuits comprise resistor-capacitor filter circuits.

11. The energy saving controller system as recited in claim 6 wherein the first and second filter circuits comprise resistor-capacitor filter circuits.

12. The energy saving controller system as recited in claim 6 wherein the variable gain differential amplifier circuit includes an amplifier circuit, a plurality of resistors for determining a gain of said amplifier circuit and a plurality of analog switches for selecting at least one resistor from the plurality of resistors to vary the gain of said amplifier circuit.

13. The energy saving controller system as recited in claim 1 wherein the control circuit regulates the magnitude of the control signal in response to the sensed increase in the measured current signal by reducing the magnitude of the control signal to approximately zero, thereby allowing the power switching circuit to produce one of the different voltages at the output port in the absence of the control signal.

14. A method for providing, from one power source, one of a plurality of different voltages to a load including at least one electrical energy consuming device, wherein switching between the different voltages is effected without power interruption to said load, the method comprising:

(a) measuring current being supplied to the load from an output port of a power switching circuit, said circuit comprising a relay and a step-down transformer, said transformer including a primary winding and a secondary winding, said secondary winding being connected in series between the positive terminal of the power source and a positive terminal of the output port, said primary winding being coupled to the power source via the relay such that the primary winding and the secondary winding have opposite polarities, thereby causing the voltage across the output port to be equal to a difference between the power source and the voltage across the secondary winding;

(b) producing a measured current signal from the power switching circuit and unrelated to an increase in voltage of the power source;

(c) applying the measured current signal to a control circuit to sense an increase in the measured current signal;

(d) outputting a control signal for a specified duration from the control circuit;

(e) regulating the magnitude of the control signal in response to said increase in the measured current signal;

(f) applying the control signal of regulated magnitude to the power switching circuit; and

(g) producing a voltage approximately equal to the power source voltage, for the specified duration, at the output port of the power switching circuit.

15. The method as recited in claim 14 wherein the step of applying the measured current signal to a control circuit to sense an increase in the measured current signal further comprises the steps of:

(a) rectifying the measured current signal;

(b) filtering the rectified signal through two filter circuits having different time constants;

(c) producing a first filtered signal and a second filtered signal;

(d) subtracting the first filtered signal from the second filtered signal to obtain a difference signal;

(e) amplifying the difference signal to produce a trigger signal; and

(f) applying the trigger signal to a control circuit.

16. The method as recited in claim 14 wherein the step of applying the control signal of regulated magnitude to the power switching circuit further comprises the steps of:

(a) applying the control signal of regulated magnitude to the relay of the power switching circuit;

(b) disconnecting the primary winding from the power source voltage; and

(c) short-circuiting the primary winding, thereby causing the secondary winding to be substantially short-circuited and the voltage across the output port of the power switching circuit to be approximately equal to the power source voltage.

17. The method as recited in claim 14 wherein the step of regulating the magnitude of the control signal in response to the increase in the measured current signal comprises the step of reducing the magnitude of the control signal to approximately zero.

18. An energy saving controller system providing, from one power source having a positive terminal and a negative terminal, one of a plurality of different voltages to a load including at least one electrical energy consuming device, the system comprising:

(a) a power switching circuit, in electrical communication with the power source, for producing one of the plurality of different voltages at an output port in response to a control signal of regulated magnitude, said power switching circuit being configured to effect switching between the different voltages without power interruption to the load;

(b) a current sensing circuit, in electrical communication with the output port of the power switching circuit, for measuring current at said output port and for producing a measured current signal; and

(c) a control circuit, in electrical communication with the power switching circuit and the current sensing circuit, for sensing an increase in the measured current demand by the load, for outputting the control signal to the power switching circuit, and for regulating the magnitude of the control signal in response to the sensed increase in the measured current signal, said control circuit comprising;

(i) a differential sensing circuit for sensing an increase in the measured current signal and for producing a trigger signal thereupon; and

(ii) a processing circuit comprising a microprocessor, coupled to the differential sensing circuit, for producing the control signal, for regulating the magnitude of the control signal in response to receipt of said trigger signal, for controlling duration of the control signal, and for regulating sensitivity of the differential sensing circuit.

19. An energy saving controller system providing, from one power source having a positive terminal and a negative terminal, one of a plurality of different voltages to a load including at least one electrical energy consuming device, the system comprising:

(a) a power switching circuit, in electrical communication with the power source, for producing one of the plurality of different voltages at an output port in response to a control signal of regulated magnitude, said power switching circuit being configured to effect switching between the different voltages without power interruption to the load;

(b) a current sensing circuit, in electrical communication with the output port of the power switching circuit, for measuring current at said output port and for producing a measured current signal;

(c) a control circuit, in electrical communication with the power switching circuit and the current sensing circuit, for sensing an increase in the measured current demand by the load, for outputting the control signal to the power switching circuit, and for regulating the magnitude of the control signal in response to the sensed increase in the measured current signal;

(d) a visual display, in electrical communication with the control circuit, for showing status of the system; and

(e) a computer interface, in electrical communication with the control circuit, for receiving inputs from a user.