Quadrac

Abstract: Apparatus and methods for AC power regulation primarily intended for inductive loads (e.g., fluorescent lights, motors, etc.) which provide substantial reduction in power consumption while also providing a leading power factor, reduced harmonic distortion, reduced crest factor and reduced noise. The system is self-adjusting for a wide range of loads and can reduce power consumption by 25 percent in lighting loads while producing minimal reduction in light output. The system utilizes a Triac (32) and parallel capacitor bank (58) in series with the load (22). The Triac (32) is turned on in response to a near-zero differential voltage measured across the Triac (32) and is turned off near the peak of each AC half cycle by shunting current around the Triac (32). The capacitor (60) absorbs the inductive turn-off voltage spike caused by the collapsing magnetic field in the ballast at the instant of Triac turn-off. This energy, in turn, provides longer on-period for the lamp, thereby permitting more light and increased operating efficiency. The turn-off time is adjusted to regulate power at a reduced level responsive to line voltage, load current and load power-sense signals.

Abstract: A power-factor-corrected power supply adapted to supply power to one or more light emitting diodes (LEDs), comprises: a triac dimmer electrically connected between an alternating current source and a bridge rectifier; a damping circuit electrically connected between the alternating current source and the bridge rectifier; a bleeder circuit configured to conduct current between a supply terminal of the bridge rectifier and ground only when a triac in the triac dimmer is not conducting current; a fast startup circuit configured to conduct current between the supply terminal of the bridge rectifier and a voltage supply terminal of a power-factor-corrected controller when the triac dimmer is initially turned on until a supply voltage capacitor coupled to the voltage supply terminal of the power-factor-corrected controller has charged; a dimming slope control circuit configured to reduce a first voltage sensed at a current sensing terminal of the power-factor-corrected controller, such that a reduced amount of current is supplied to the one or more LEDs at a given firing angle, wherein the first voltage is representative of a current flowing through a primary winding of a flyback transformer; and a dummy load circuit provided in parallel with the one or more LEDs to draw a holding current for the triac only after the triac is turned on.

Abstract: (NOTE: Each chapter concludes with Problems and Equations.) 1. Power Electronics. 2. Power Diodes. 3. Power Transistors. 4. Thyristor Devices. 5. Single-Phase Uncontrolled Rectifiers. 6. Single-Phase Controlled Rectifiers. 7. Three-Phase Uncontrolled Rectifiers. 8. Three-Phase Controlled Rectifiers. 9. DC Choppers. 10. Inverters. 11. AC Voltage Controller. 12. Static Switches. Index.

Abstract: Disclosed is circuitry for controlling the flow of current from an AC source to a load and includes a bilateral semiconductor switch such as a semiconductor triac connected in parallel with the contacts of an electromechanical relay. The relay and triac are connected in series with the AC source and the load. Circuit means are connected between a gate electrode of the triac and circuit input terminals to which the AC source is connected and provides turn-on gate current for the triac prior to and during the closure of the electromechanical relay contacts to prevent effects of contact bounce. This circuit means also provides a sustaining or hold current to the triac subsequent to the opening of the relay contacts and thereby prevents contact arcing. The triac conducts before the relay contacts close and after the relay contacts open.