Current zero crossing detector in a dimmer circuit
First Claim
1. A method of operating a switch for controlling the delivery of power having a current component to a load having an inductive component in a phase controlled dimmer circuit to reduce the occurrence of voltage spiking, the method comprising:
- comparing a voltage across the switch that selectively switches power to the load with a reference voltage during a conductive state of the switch; and
generating a biasing voltage for controlling the switch, wherein the biasing voltage is adjusted to a level to cause the switch to operate in a saturation mode if the voltage across the switch is below the reference voltage, and the switch is caused to automatically commutate to its off state when the current through the load is substantially zero by removing the biasing voltage when the voltage across the switch drops to zero due to the current through the load being substantially zero.
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Accused Products
Abstract
A method and circuit for controlling the delivery of power having a current component to a load having an inductive component, the method comprising selectively switching power to the load with a switch, wherein the switch is caused to operate at the threshold of saturation during a conduction state such that the switch self commutates to its off state when the magnitude of the current through the load is substantially zero. The method and circuit may be used in a number of applications for detecting a current zero crossing and may be applied to circuits such as dimmer circuits.
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Citations
11 Claims
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1. A method of operating a switch for controlling the delivery of power having a current component to a load having an inductive component in a phase controlled dimmer circuit to reduce the occurrence of voltage spiking, the method comprising:
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comparing a voltage across the switch that selectively switches power to the load with a reference voltage during a conductive state of the switch; and generating a biasing voltage for controlling the switch, wherein the biasing voltage is adjusted to a level to cause the switch to operate in a saturation mode if the voltage across the switch is below the reference voltage, and the switch is caused to automatically commutate to its off state when the current through the load is substantially zero by removing the biasing voltage when the voltage across the switch drops to zero due to the current through the load being substantially zero. - View Dependent Claims (2, 3, 4, 11)
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5. A circuit for controlling the delivery of power having a current component to a load having an inductive component for use in a phase controlled dimmer circuit to reduce the occurrence of voltage spiking, the circuit comprising:
a switch and a switch controller for controlling a biasing voltage applied to the switch, wherein the switch controller compares a voltage across the switch with a reference voltage and adjusts the biasing voltage to a level to cause the switch to operate in a saturation mode when the voltage across the switch falls below the reference voltage and the switch is caused to automatically commutate to its off state when the current through the load is substantially zero, by removing the biasing voltage when the voltage across the switch drops to zero due to the current through the load being substantially zero. - View Dependent Claims (6, 7, 8, 9, 10)
Specification