Abstract: A common-mode voltage cancellation (CMVC) circuit, is disclosed. The circuit includes a first set of coupled inductors, each having a primary winding defining a first polarity, and a secondary winding. The secondary windings are electrically coupled in series. Each primary winding receives a phase voltage having a common mode voltage component from a respective input line. The circuit includes a second set of coupled inductors comprising at least one primary winding and at least one secondary winding The at least one primary winding receives a second voltage from the series connected secondary windings of the first set of coupled inductors. Each at least one secondary winding is coupled in series with a respective input line such that the common mode voltage component received on input lines will be reduced at an output of the set of secondary windings.

Abstract: A phase-shifted PWM dc-to-dc converter includes a pair of switched half-bridges defining taps. The primary of an output transformer is coupled across the taps to receive AC, and produces transformed AC which is rectified and filtered to produce the output dc. Zero-voltage-switching (ZVS) is maintained over the full range from zero load current to maximum load current by the use of an auxiliary circuit including an “inverting” second transformer having primary and secondary windings serially coupled with capacitors. The primary-capacitor serial circuit is connected between a first half-bridge tap and reference potential, and the secondary-capacitor serial circuit is connected by an inductance between second half-bridge tap and a reference potential.

Abstract: A power converter generates direct voltage and includes a phase-shifted PWM bridge with first and second controllable switches connected as a half-bridge with a first tap, for generating AC at the first tap. An output transformer includes a primary winding coupled to the first tap. A full-wave rectifier is connected to a secondary winding of the output transformer. A filter is coupled to the full-wave rectifier for producing filtered output direct voltage. Resonances create surges which may undesirably result in energy loss. A second transformer includes a primary winding coupled to receive the resonant surges and a secondary winding at which transformed surges appear. A second rectifier is coupled to the secondary winding of the second transformer, for rectifying the surges. The energy of the surges is returned or coupled to the source or load. In one embodiment, the full-wave rectifier is a bridge rectifier.

Abstract: Low-power auxiliary circuitry is added to a resonant converter for providing high efficiency operation, low EMI, and tight output voltage control over a wide load range. There is an auxiliary circuit corresponding to each half-bridge connection of main switching devices, each auxiliary circuit including a half-bridge connection of auxiliary switching devices with the junction therebetween coupled to the junction between the main switching devices of the corresponding half-bridge. Under heavy load conditions, sufficient energy is stored in the main resonant inductor to commutate the junctions joining the main switching devices in the resonant converter, resulting in zero-voltage switching for the main switching devices.

Abstract: The present invention discloses a method and system for controlling a power supply by delivering stable output voltage independent of load. The control system includes a sensor for sensing a state variable, a fuzzy logic controller for generating a control action, and an actuator for regulating the power supply in accordance with the control action. The fuzzy logic controller generates a fuzzy logic knowledge base using low-level fuzzy logic controllers and a mode selector in one embodiment and a fuzzy logic proportional integral controller in another embodiment. The generated fuzzy logic knowledge base is compiled in a look-up table and is used to quickly and efficiently control a power supply device such as a resonant converter.

Abstract: A power distribution system including a dual active bridge converter (DABC) distributes a regulated high-frequency, edge-resonant, square wave ac output voltage from an unregulated dc voltage source. The DABC-includes a primary-side half-bridge connection of switching devices and a secondary-side half-bridge connection of switching devices which are coupled by an intermediate high-frequency transformer. An ac distribution bus is connected to the regulated secondary side of the transformer. The primary-side and secondary-side connections of switching devices are phase-shifted in a manner to provide a regulated high-frequency square-wave voltage on the ac distribution bus, which is distributed via a low-impedance distribution bus to a plurality of simple point-of-load converters.

Abstract: A series resonant inverter is controlled to maintain a substantially constant gain and a substantially constant bandwidth, thereby ensuring stable operation under all operating conditions. A load compensating gain control circuit generates a unique gain or attenuation factor for each unique set of output load conditions. To maintain constant gain, inverter gain for each set of operating conditions is multiplied by the corresponding gain or attenuation factor. Bandwidth is increased (or decreased) and maintained constant to ensure stable operation.

Abstract: A series resonant inverter is controlled to provide a substantially constant output voltage to a load. The control utilizes a combination of optimal control methods and phase modulation to enable time optimal responses to changes in state of the system. State determinants (including resonant capacitor voltage, resonant inductor current, source voltage, and output load voltage) are continuously monitored, and an optimal control signal is generated therefrom. When operating within the operable frequency range of the inverter's controllable switch means, frequency is varied to maintain proper operation. When operating at an extremity of the operable frequency range, phase modulation is employed.

Abstract: A circuit for "resetting" snubbers in a series resonant bridge inverter maintains lossless snubber action during light-load and no-load inverter operation and during operation near resonance. Series resonant circuit operation is controlled to be above the resonant frequency to ensure operation at a lagging power factor. The snubber-resetting operation is facilitated by a relatively small inductor connected across the output terminals of the series resonant inverter.

Abstract: An external resistance is presented between the gate and cathode of a thermally sensitive thyristor which varies in accordance with a changing voltage applied across the thyristor. The changing voltage sweeps the varying external resistance through its operating range which in turn expands the region of temperature sensitivity with respect to breakover voltage by sweeping the shifting curves of switching temperature vs. gate to cathode resistance for the thyristor. In preferred form, a field effect transistor (FET) (10) is connected between the gate (8) and cathode (4) of the thermally sensitive thyristor (6) and is biased by the same voltage supply applied across the thyristor. The FET presents an external gate to cathode resistance which varies in accordance with the changing bias level on the FET, which is the same changing bias applied across the thyristor. The range of variance of this added external resistance must be between 10,000 ohms and 1 megohm.

Abstract: A series resonant inverter is controlled to provide a substantially constant output voltage to a load. The control utilizes a combination of optimal control methods and phase modulation to enable time optimal responses to changes in state of the system. State determinants (including resonant capacitor voltage, resonant inductor current, source voltage, and output load voltage) are continuously monitored, and an optimal control signal is generated therefrom. When operating within the operable frequency range of the inverter's controllable switch means, frequency is varied to maintain proper operation. When operating at an extremity of the operable frequency range, phase modulation is employed.