Method for varying the power consumption of capacitive loads

• US 20040207337A1
• Filed: 03/29/2004
• Published: 10/21/2004
• Est. Priority Date: 04/04/2003
• Status: Active Grant

• Current Assignee: ABL IP Holding LLC (Acuity Brands, Inc.)
• Original Assignee: Patent-Treuhand-Gesellschaft Fur Elektrische Gluhlampen mbH (Ams-Osram AG)
• Inventors: Kreittmayr, Josef, Fischer, Klaus
• Granted Patent: US 7,132,802 B2
• Time in Patent Office: Days
• US Class Current: 315/224
• CPC Class Codes: H02M 7/217 using semiconductor devices only
• CPC Class Codes: H05B 41/2853 against abnormal power supply conditions
• CPC Class Codes: H05B 41/3924 by phase control, e.g. using a triac H05B41/3922 takes precedence
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

The invention relates to a method for varying the power consumption of capacitive loads, in particular compact fluorescent lamps which are operated using a phase-gating dimmer by means of a converter (step-up converter). According to the invention, in the case of a nonconducting dimmer (i.e. no system power supply to the load), the switch (T1) in the converter (step-up converter) is closed. In the case of a conducting dimmer (i.e. when a system voltage is applied to the load), the step-up converter operation takes place until a predetermined maximum voltage is reached across the smoothing capacitor of the load.

Claims

1. A method for varying the power consumption of loads having a capacitive input on an AC voltage power supply system by connecting and disconnecting, at the system frequency, the system power supply in each system half-cycle, in that

a) as long as the system power supply is disconnected, a current path bridging the load inputs is created, and in that,

b) when the system power supply is connected, a smoothing capacitor is charged by means of a converter until the voltage across the smoothing capacitor of the load reaches a predetermined maximum value.

2. The method as claimed in claim 1, in that the converter is a step-up converter.

3. The method as claimed in claim 1, or in that the maximum value is reduced when the time at which the system power supply is in each case connected falls below a predetermined minimum value.

4. The method as claimed in claim 1, in that, when the characteristic of the system power supply applied to the load is constant, the converter is permanently deactivated.

5. A circuit for carrying out the method as claimed in claim 1, in that it has a current path which can be connected and disconnected and which is designed to bridge the inputs of a load, and in that a control element is provided which is designed to detect the voltage across the smoothing capacitor of a load and its system power supply and to connect and disconnect the current path.

6. The circuit as claimed in claim 5, in that it is connected to in each case one system-side input of a rectifier via a first and a second resistor.

7. The circuit as claimed in claim 5, in that it is designed to evaluate a signal produced by the system power supply and to produce a signal for controlling the power consumption of the load.

8. The circuit as claimed in claim 5, in that it has a step-up converter, the current path being guided via the inductor of the step-up converter and a transistor of the step-up converter which can be controlled by the control element, and the step-up converter being designed to operate, once the system power supply has been applied to the load, until the voltage across the smoothing capacitor of the load reaches a predetermined maximum value.

9. The circuit as claimed in claim 5, in that it has an interface circuit connected upstream of it which is designed to short-circuit the inputs of the load upstream of the current path and the inductor and thus to bypass the current path and the inductor as long as no power is being supplied to the load.

10. The circuit as claimed in claim 4, in that the current path is designed such that, during operation of the step-up converter, it carries on average over time a current which corresponds at least to a holding current required for maintaining the closed state of a triac in the system power supply.

11. An electrical ballast for a lamp having the control circuit as claimed in claim 4 for operation using a phase-gating dimmer.

12. The method as claimed in claim 2, in that the maximum value is reduced when the time at which the system power supply is in each case connected falls below a predetermined minimum value.

13. The method as claimed in claim 2, in that, when the characteristic of the system power supply applied to the load is constant, the converter is permanently deactivated.

14. The method as claimed in claim 3, in that, when the characteristic of the system power supply applied to the load is constant, the converter is permanently deactivated.

15. The circuit as claimed in claim 6, in that it is designed to evaluate a signal produced by the system power supply and to produce a signal for controlling the power consumption of the load.

16. The circuit as claimed in claim 6, in that it has a step-up converter, the current path being guided via the inductor of the step-up converter and a transistor of the step-up converter which can be controlled by the control element, and the step-up converter being designed to operate, once the system power supply has been applied to the load, until the voltage across the smoothing capacitor of the load reaches a predetermined maximum value.

17. The circuit as claimed in claim 6, in that it has an interface circuit connected upstream of it which is designed to short-circuit the inputs of the load upstream of the current path and the inductor and thus to bypass the current path and the inductor as long as no power is being supplied to the load.

18. The circuit as claimed in claim 7, in that it has an interface circuit connected upstream of it which is designed to short-circuit the inputs of the load upstream of the current path and the inductor and thus to bypass the current path and the inductor as long as no power is being supplied to the load.

19. The circuit as claimed in claim 5, in that the current path is designed such that, during operation of the step-up converter, it carries on average over time a current which corresponds at least to a holding current required for maintaining the closed state of a triac in the system power supply.

20. The circuit as claimed in claim 6, in that the current path is designed such that, during operation of the step-up converter, it carries on average over time a current which corresponds at least to a holding current required for maintaining the closed state of a triac in the system power supply.