Smooth switching power control circuit and method
First Claim
1. A power control circuit having a relatively smooth turn-on conduction transition characteristic and a relatively low forward voltage drop and power consumption, the power control circuit controlling the amount of power supplied to a load from a source which supplies AC power in alternating half-cycles of AC voltage and current, the power control circuit comprising:
- a pair of terminals adapted to be connected in series with the load and the power source and between which current flows to control the amount of power supplied to the load from the source;
a controlled transition circuit electrically connected to conduct current between the terminals when in a fully conductive state and not to conduct current between the terminals when in a non-conductive state, the controlled transition circuit transitioning from the non-conductive state to the fully conductive state over a first predetermined amount of time, the controlled transition circuit creating a first predetermined voltage across the terminals when in the fully conductive state; and
a low forward voltage conduction circuit electrically connected to conduct current between the terminals when in a conductive state and to divert current to the controlled transition circuit when in a non-conductive state, the low forward voltage conduction circuit transitioning from the non-conductive state to the conductive state over a second predetermined amount of time, the low forward voltage conduction circuit creating a second predetermined voltage across the terminals when in the conductive state, and the second predetermined voltage being substantially less than the first predetermined voltage.
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Accused Products
Abstract
A power control circuit achieves a relatively smooth turn-on conduction transition characteristic and a relatively low power consumption. A controlled transition circuit conducts current to a load when in a fully conductive state. The transition circuit transitions from a non-conductive state to the fully conductive state over a predetermined amount of time to limit the di/dt and the interference signals generated by the di/dt. A low forward voltage conduction circuit also conducts current to the load in a conductive state and diverts current to the transition circuit when in a non-conductive state. The conduction circuit creates a second predetermined voltage across the terminals when in the conductive state which is substantially less than the first predetermined voltage to reduce the power consumption.
99 Citations
30 Claims
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1. A power control circuit having a relatively smooth turn-on conduction transition characteristic and a relatively low forward voltage drop and power consumption, the power control circuit controlling the amount of power supplied to a load from a source which supplies AC power in alternating half-cycles of AC voltage and current, the power control circuit comprising:
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a pair of terminals adapted to be connected in series with the load and the power source and between which current flows to control the amount of power supplied to the load from the source; a controlled transition circuit electrically connected to conduct current between the terminals when in a fully conductive state and not to conduct current between the terminals when in a non-conductive state, the controlled transition circuit transitioning from the non-conductive state to the fully conductive state over a first predetermined amount of time, the controlled transition circuit creating a first predetermined voltage across the terminals when in the fully conductive state; and a low forward voltage conduction circuit electrically connected to conduct current between the terminals when in a conductive state and to divert current to the controlled transition circuit when in a non-conductive state, the low forward voltage conduction circuit transitioning from the non-conductive state to the conductive state over a second predetermined amount of time, the low forward voltage conduction circuit creating a second predetermined voltage across the terminals when in the conductive state, and the second predetermined voltage being substantially less than the first predetermined voltage. - 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 power control circuit having a relatively smooth turn-on conduction transition characteristic for controlling the amount of power supplied to a load, the dimming circuit adapted to be connected in series with the load and a source of AC power which is applied in alternating half-cycles of AC voltage and AC current, the power control circuit comprising:
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a controlled transition circuit to conduct current initially through the load, said controlled transition circuit comprising; a switching transistor having a control terminal; a bias signal generating circuit connected to the control terminal of the transistor to generate a bias signal which increases in magnitude over a first predetermined amount of time, the magnitude of the bias signal generally establishing the magnitude of conductivity of the switching transistor; and the switching transistor responding to the bias signal applied at the control terminal to transition from a non-conductive state to a fully conductive state over the duration of the first predetermined amount of time; and a low forward voltage conduction circuit connected to the transition circuit, the conduction circuit operatively conducting current through the load after the switching transistor achieves the fully conductive state, the low forward voltage conduction circuit comprising; a thyristor connected in series with the load and the source and operative to be triggered into a conductive state in response to the application of a trigger signal applied thereto; a trigger signal developing device responsive to the current conducted to the load by the switching transistor to develop a trigger signal from the current conducted by the switching transistor; and a delay circuit connected between the trigger signal developing device and the thyristor to delay the application of the trigger signal to the thyristor for a predetermined amount of time sufficient to allow the transistor to achieve the fully conductive state. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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27. A method of controlling the amount of power supplied to a load connected to an AC power source while reducing generation of interference signals and while consuming small amounts of power, said method comprising the following steps:
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attaching a switching transistor substantially in series with the load and the AC power source; biasing the switching transistor from a non-conductive state to a first conductive state over a predetermined amount of time, said predetermined amount of time being substantially long enough to reduce its change in current per change in time to a sufficiently low value to limit substantially the interference signal generation occurring as a result of the transition from the non-conductive state to the first conductive state; establishing a predetermined voltage across the switching transistor in the first conductive state; attaching a thyristor in series with the load and the AC power source and substantially in parallel with the switching transistor; triggering the thyristor from a non-conductive state into a second conductive state after expiration of the predetermined amount of time; and establishing a predetermined voltage across the thyristor in the second conductive state which is less than the voltage across the switching transistor in the first conductive state. - View Dependent Claims (28, 29, 30)
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Specification