Power supply for a load control device
First Claim
1. A power supply for use in a load control device for controlling the amount of power delivered to an electrical load from an AC power source, the load control device operable to receive an AC voltage waveform of the AC power source, the power supply operable to generate a DC output voltage for powering a remote control device, the power supply comprising:
- an energy storage element across which the output voltage is generated, the energy storage element arranged to conduct an asymmetrical output current through the remote control device;
a controllably conductive switching circuit coupled in series electrical connection with the energy storage element, the controllably conductive switching circuit configured to conduct a charging current from the AC power source through the energy storage element for charging the energy storage element to produce the output voltage, the controllably conductive switching circuit configured to switch to a conductive state after the magnitude of the AC voltage waveform exceeds approximately the magnitude of the DC voltage during a half-cycle of the AC voltage waveform;
a threshold detect circuit configured to receive a first control signal representative of the magnitude of the output voltage and a second control signal representative of the amount of time that the energy storage element has been charging during the half-cycle; and
a latching circuit coupled to the controllably conductive switching circuit and the threshold detect circuit, the latching circuit configured to cause the controllably conductive switching circuit to become non-conductive in response to the magnitude of the output voltage and the amount of time that the energy storage element has been charging during the half-cycle, resulting in the magnitude of the charging current conducted from the AC power source through the energy storage element being approximately the same each half-cycle.
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Accused Products
Abstract
A power supply for a load control device generates a DC voltage and provides an asymmetrical output current, while drawing a substantially symmetrical input current. The power supply comprises a controllably conductive switching circuit for controllably charging an energy storage capacitor across which the DC voltage is produced. The energy storage capacitor begins charging at the beginning of a half-cycle and stops charging after a charging time in response to the magnitude of the DC voltage and the amount of time that the energy storage capacitor has been charging during the present half-cycle. The charging time is maintained substantially constant from one half-cycle to the next. The power supply is particularly beneficial for preventing asymmetrical current from flowing in a multiple location load control system having a master load control device supplying power to a plurality of remote load control devices all located on either the line-side or the load-side of the system.
58 Citations
20 Claims
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1. A power supply for use in a load control device for controlling the amount of power delivered to an electrical load from an AC power source, the load control device operable to receive an AC voltage waveform of the AC power source, the power supply operable to generate a DC output voltage for powering a remote control device, the power supply comprising:
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an energy storage element across which the output voltage is generated, the energy storage element arranged to conduct an asymmetrical output current through the remote control device; a controllably conductive switching circuit coupled in series electrical connection with the energy storage element, the controllably conductive switching circuit configured to conduct a charging current from the AC power source through the energy storage element for charging the energy storage element to produce the output voltage, the controllably conductive switching circuit configured to switch to a conductive state after the magnitude of the AC voltage waveform exceeds approximately the magnitude of the DC voltage during a half-cycle of the AC voltage waveform; a threshold detect circuit configured to receive a first control signal representative of the magnitude of the output voltage and a second control signal representative of the amount of time that the energy storage element has been charging during the half-cycle; and a latching circuit coupled to the controllably conductive switching circuit and the threshold detect circuit, the latching circuit configured to cause the controllably conductive switching circuit to become non-conductive in response to the magnitude of the output voltage and the amount of time that the energy storage element has been charging during the half-cycle, resulting in the magnitude of the charging current conducted from the AC power source through the energy storage element being approximately the same each half-cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A load control device for controlling the power delivered to an electrical load from an AC power source in response to a remote control device, the load control device and the remote control device adapted to be coupled in series electrical connection between the source and the load, such that the load control device and the remote control device may both conduct a load current from the AC power source to the electrical load without a neutral connection to the neutral side of the AC power source, the remote control device adapted to be further coupled to the load control device through an accessory wiring, the load control device comprising:
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a bidirectional semiconductor switch adapted to be coupled in series between the source and the load for controlling the power delivered to the load; a controller coupled to a control input of the bidirectional semiconductor switch for controlling the power delivered to the load; and a power supply for generating a link voltage for powering the remote control device via the accessory wiring, the power supply conducting an asymmetrical output current and drawing a substantially symmetrical input current from the AC power source. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification