Power controller

• US 20070063680A1
• Filed: 08/27/2004
• Published: 03/22/2007
• Est. Priority Date: 09/05/2003
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Ham, Nicholas
• Granted Patent: US 7,936,576 B2
• Time in Patent Office: Days
• US Class Current: 323/237
• CPC Class Codes: G05F 1/66 Regulating electric power
• CPC Class Codes: H02M 1/081 wherein the phase of the control voltage is adjustable with reference to the AC source
• CPC Class Codes: H02M 1/10 Arrangements incorporating converting means for enabling loads to be operated at will from different kinds of power supplies, e.g. from ac or dc
• CPC Class Codes: H02P 7/295 of the kind having a thyristor or the like in series with the power supply and the motor

Abstract

A power controller (10) includes a controller (11) and a trigger circuit (12). When the voltage of a power supply received at terminals T1 exceeds a threshold, for example 120 V RMS, reverse-connected Zener diodes Z1 to Z3 conduct and switch on a transistor Q1. This results in a transistor Q2 being switched off and a normally open relay SW1 remaining open. The switching or triggering phase angle of a triac THY1 thus is determined by the speed at which a capacitor C4 is charged to a triggering voltage by current flowing through resistors R6, R7, R8 and VR1. In this situation, the triggering phase angle is such that a 240 V AC input supply provides an effective 110 V AC output at terminals T3 when VR1 is at maximum power setting (zero Ohms). When the voltage of the received power supply is less than the threshold, the transistor Q1 is switched off and the relay SW1 is activated. This bypasses resistor R6 and causes the switching or triggering phase angle to adopt a value of about zero degrees when VR1 is at maximum power setting, such that the voltage of the output power supply terminals T3 is substantially the same as that received at terminals T1.

Claims

1. A power controller for controlling the power supplied from power supplies of different voltage ratings to a load having an input voltage threshold, comprising a controller operable to control a trigger circuit to have a triggering phase angle greater when the power supply voltage input to the controller exceeds a threshold dependent on the input voltage threshold of the load than when the threshold is not exceeded.

2. A power controller as claimed in claim 1, in which the controller effects change in the resistance of a resistive circuit forming part of the trigger circuit.

3. A power controller as claimed in claim 2, in which the change in the resistance of the resistive circuit is a step change.

4. A power controller as claimed claim 2, in which the resistive circuit is operable to provide current for charging a capacitive circuit connected to the control electrode of a switching semiconductor circuit or device forming part of the trigger circuit.

5. A power controller as claimed in claim 2, arranged such that, before energization of the power controller, the resistive circuit has a resistance corresponding to that present when the voltage of the input power supply exceeds the input voltage threshold of the load.

6. A power controller as claimed in claim 2, wherein the controller operates a switch forming part of the resistive circuit

7. A power controller as claimed in claim 6, wherein the switch is a relay.

8. A power controller as claimed in claim 7, wherein the switch is a photoMOS relay.

9. A power controller as claimed in claim 6, wherein the switch is normally open.

10. A power controller as claimed in claim 2, wherein the controller includes a circuit operable to produce a step signal change, for effecting the change in the resistance of the resistive circuit when the voltage of the input power supply exceeds the input voltage threshold of the load.

11. A power controller as claimed in claim 7, wherein the circuit includes one or more Zener diodes.

12. A power controller as claimed in claim 2, wherein the resistive circuit includes a potentiometer

13. A power controller as claimed in claim 12, wherein the potentiometer is connected with a power switch such that operation of the power switch controls the potentiometer temporarily to adopt a high resistance.

15. An electrical device including a power controller as claimed in claim 1.

14. A power controller for controlling the power supplied from power supplies of different voltage ratings to a load having an input voltage threshold, comprising a controller operable to control a trigger circuit such that the trigger phase angle of the trigger circuit is retarded when the power supply voltage input to the controller exceeds the input voltage threshold of the load.