Power Supply for a Load Control Device
First Claim
1. A power supply for 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 voltage, the power supply comprising:
- an energy storage element;
a controllably conductive switching circuit coupled in series electrical connection with the energy storage element for selectively charging the energy storage element to produce the DC voltage, the controllably conductive switching circuit operable to become conductive after the magnitude of the AC voltage waveform exceeds approximately the magnitude of the DC voltage waveform during a half-cycle of the AC voltage waveform; and
a latching circuit coupled to the controllably conductive switching circuit, the latching circuit adapted to cause the controllably conductive switching circuit to become non-conductive in response to the magnitude of the DC voltage and the amount of time that the energy storage element has been charging during the 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.
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Citations
33 Claims
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1. A power supply for 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 voltage, the power supply comprising:
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an energy storage element; a controllably conductive switching circuit coupled in series electrical connection with the energy storage element for selectively charging the energy storage element to produce the DC voltage, the controllably conductive switching circuit operable to become conductive after the magnitude of the AC voltage waveform exceeds approximately the magnitude of the DC voltage waveform during a half-cycle of the AC voltage waveform; and a latching circuit coupled to the controllably conductive switching circuit, the latching circuit adapted to cause the controllably conductive switching circuit to become non-conductive in response to the magnitude of the DC voltage and the amount of time that the energy storage element has been charging during the half-cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A power supply for 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 comprising:
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an output for providing the DC voltage and adapted to conduct an asymmetrical output current; an energy storage element, the DC voltage generated across the energy storage element; and a controllably conductive switching circuit coupled in series electrical connection with the energy storage element for selectively charging the energy storage element to produce the DC voltage, such that the power supply draws an input current from the AC power source; wherein the controllably conductive switching circuit is controlled such that the input current is substantially symmetrical. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A multiple location load control system for controlling the power delivered to an electrical load from an AC power source, the system comprising:
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a main load control device comprising a power supply operable to draw an input current from the AC power source and to generate a link voltage; and a remote load control device comprising a power supply, the main load control device and the remote load control device adapted to be coupled in series electrical connection between the AC power source and the electrical load, such that the main load control device and the remote load control device are both operable to 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 load control device adapted to be further coupled to the main load control device through an accessory wiring, the main load control device operable to provide the link voltage on the accessory wiring to allow the power supply of the remote device to charge, such that an output current of the power supply of the main load control device is asymmetrical; wherein the input current of the power supply of the main load control device is substantially symmetrical. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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27. A method for generating a DC power supply voltage for use in a load control device for controlling the amount of power delivered to an electrical load from an AC power source, the method comprising the steps of:
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beginning to charge an energy storage element for generating the DC power supply voltage during a half-cycle of the AC power source; generating a first control signal representative of the magnitude of the DC power supply voltage; generating a second control signal representative of the amount of time that the energy storage element has been charging during the half-cycle; and causing the energy storage element to stop charging in response to both the first and second control signals. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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Specification