Smart electronic switch for low-power loads
First Claim
1. A two-wire electronic switch adapted to be coupled between an AC power source and an electrical load for turning the electrical load on and off, the electronic switch comprising:
- a controllably conductive device adapted to be coupled in series electrical connection between the source and the load, the controllably conductive device adapted to conduct a load current through the load when the controllably conductive device is conductive;
a controller operatively coupled to the controllably conductive device for controlling the controllably conductive device to be conductive and non conductive to turn the load on and off, respectively;
an output capacitor operable to develop a DC supply voltage for powering the controller; and
an in-line power supply coupled in series with the controllably conductive device, the in-line power supply further coupled to the output capacitor for controlling when the output capacitor charges in order to generate the DC supply voltage across the output capacitor when the controllably conductive device is conductive, such that the output capacitor stops charging when the magnitude of the DC supply voltage reaches a maximum DC supply voltage threshold, a voltage developed across the in-line power supply when the output capacitor is charging having a substantially small magnitude as compared to a peak voltage of an AC line voltage of the AC power source, the output capacitor adapted to conduct the load current for at least a portion of a line cycle of the AC power source when the controllably conductive device is conductive;
wherein the in-line power supply controls when the output capacitor charges asynchronously with respect to the frequency of the AC power source, such that the output capacitor is operable to start and stop charging at any time during each half cycle, the power supply operable to start and to stop charging the output capacitor at least once during each half cycle of the AC power source; and
wherein the controller is operable to determine when the magnitude of the DC supply voltage reaches the maximum DC supply voltage threshold, and to render the controllably conductive device non-conductive immediately after the DC supply voltage reaches the maximum DC supply voltage threshold.
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Accused Products
Abstract
A two-wire smart load control device, such as an electronic switch, for controlling the power delivered from a power source to an electrical load comprises a relay for conducting a load current through the load, a controller for rendering the relay conductive and non-conductive, and an in-line power supply coupled in series with the relay for generating a supply voltage across a capacitor when the relay is conductive. The power supply controls when the capacitor charges asynchronously with respect to the frequency of the source. The capacitor conducts the load current for at least a portion of a line cycle of the source when the relay is conductive. The controller is operable to determine when the magnitude of the supply voltage reaches a maximum supply voltage threshold, and render the relay non-conductive immediately after the supply voltage reaches the maximum supply voltage threshold.
37 Citations
18 Claims
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1. A two-wire electronic switch adapted to be coupled between an AC power source and an electrical load for turning the electrical load on and off, the electronic switch comprising:
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a controllably conductive device adapted to be coupled in series electrical connection between the source and the load, the controllably conductive device adapted to conduct a load current through the load when the controllably conductive device is conductive; a controller operatively coupled to the controllably conductive device for controlling the controllably conductive device to be conductive and non conductive to turn the load on and off, respectively; an output capacitor operable to develop a DC supply voltage for powering the controller; and an in-line power supply coupled in series with the controllably conductive device, the in-line power supply further coupled to the output capacitor for controlling when the output capacitor charges in order to generate the DC supply voltage across the output capacitor when the controllably conductive device is conductive, such that the output capacitor stops charging when the magnitude of the DC supply voltage reaches a maximum DC supply voltage threshold, a voltage developed across the in-line power supply when the output capacitor is charging having a substantially small magnitude as compared to a peak voltage of an AC line voltage of the AC power source, the output capacitor adapted to conduct the load current for at least a portion of a line cycle of the AC power source when the controllably conductive device is conductive; wherein the in-line power supply controls when the output capacitor charges asynchronously with respect to the frequency of the AC power source, such that the output capacitor is operable to start and stop charging at any time during each half cycle, the power supply operable to start and to stop charging the output capacitor at least once during each half cycle of the AC power source; and wherein the controller is operable to determine when the magnitude of the DC supply voltage reaches the maximum DC supply voltage threshold, and to render the controllably conductive device non-conductive immediately after the DC supply voltage reaches the maximum DC supply voltage threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A two-wire electronic switch for controlling the power delivered from an AC power source to an electrical load, the electronic switch comprising:
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a latching relay adapted to be coupled in series electrical connection between the source and the load for turning the load on and off; a controller operatively coupled to the relay for turning the load on and off; an output capacitor operable to develop a DC supply voltage for powering the controller; and an in-line power supply coupled in series electrical connection with the relay, the in line power supply further coupled to the output capacitor for generating the DC supply voltage across the output capacitor when the relay is conductive, the power supply comprising a bidirectional semiconductor switch coupled in series with the relay and in parallel with the output capacitor, such that the output capacitor is operable to charge when the relay is conductive and the bidirectional semiconductor switch is non conductive, the bidirectional semiconductor switch rendered conductive when the magnitude of the DC supply voltage reaches a maximum DC supply voltage threshold and rendered non-conductive when the magnitude of the DC supply voltage drops to a minimum DC supply voltage threshold, the output capacitor adapted to conduct the load current for at least a portion of a line cycle of the AC power source when the relay is conductive; wherein the controller is operable to determine when the magnitude of the DC supply voltage reaches the maximum DC supply voltage threshold, and to render the relay non-conductive immediately after the DC supply voltage reaches the maximum DC supply voltage threshold.
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Specification