Resonant switch topologies operating under the principle of zero-current switching (ZCS) and zero-voltage switching (ZVS) are introduced to minimize switching losses, stresses, and noises. Using the resonant switch concept, a host of new quasi-resonant converters (QRCs) are derived from conventional PWM converters. They are capable of operating in the megahertz range, with a significant improvement in performance and power density. Performances of ZCS and ZVS QRCs are compared. Power stages, gate drives, and feedback controls are discussed. >

High-frequency quasi-resonant converter technologies

An inverter for use in connecting a DC power source to the utility grid includes a single DC-DC conversion stage, maximum (source) power tracking, and current control based on feed-forward compensation as a function of an input power commanding voltage, rectified utility line voltage, and either a scaled and squared inverse or a scaled inverse of RMS utility line voltage. Various embodiments also include over-voltage, over-current, under-voltage, and over-temperature protection, and a stand-by battery with its battery management control, while others adapt a multiple-channel front-end distributed power system with distributed maximum power tracking to serve as a single DC power source input to the inverter system downstream with controllers, emergency or auxiliary loads, and alternative current feedback control systems for providing an in-phase output current with respect to the utility grid voltage while absorbing maximum power available from the DC power source and minimally utilizing the stand-by battery for maximal system reliability.

Solar array inverter with maximum power tracking

A power system having a power converter with an adaptive controller. The power system is coupled to a load and includes a power system controller that receives a signal indicating a system operational state of the load and selects a power converter operational state as a function thereof. The power system also includes a power converter with a power switch that conducts for a duty cycle to provide a regulated output characteristic at an output thereof. The power converter also includes a controller that receives a command from the power system controller to enter the power converter operational state and provides a signal to control the duty cycle of the power switch as a function of the output characteristic and in accordance with the command, thereby regulating an internal operating characteristic of the power converter to improve an operating efficiency thereof as a function of the system operational state.

Power system with power converters having an adaptive controller

A controller for a power converter and method of operating the same employable with a bridge rectifier having first and second synchronous rectifier switches. In one embodiment, the controller includes an amplifier configured to enable a turn-on delay for the first synchronous rectifier switch. The controller also includes a discharge switch having first and second switched terminals coupled to gate and source terminals, respectively, of the first synchronous rectifier switch and configured to discharge a gate-to-source capacitance of the first synchronous rectifier switch to enable a turn off thereof.

Controller for a synchronous rectifier switch

A power converter employing a tapped inductor and method of operating the same. In one embodiment, the power converter includes first and second tapped inductors including a tapped winding having a first section and a second section with a tap therebetween. The power converter also includes first and second active phase legs including a main switch series-coupled with an input node of the power converter and the first section of the tapped windings of the first and second tapped inductors, respectively. The first and second active phase legs also include an auxiliary switch interposed between the second section of the tapped windings of the first and second tapped inductors, respectively, and an output node of the power converter.

Power converter employing a tapped inductor and integrated magnetics and method of operating the same

A multiloop control scheme for quasi-resonant converters (QRCs) is described. Like current-mode control for pulse width modulation (PWM) converters, this control offers excellent transient response and replaces the voltage-controlled oscillator (VCO) with a simple comparator. In this method, referred to as current-sense frequency modulation (CSFM), a signal proportional to the output-inductor current is compared with an error voltage signal to modulate the switching frequency. The control can be applied to either zero-voltage-switched (ZVS) or zero-current-switched (ZCS) QRCs. Computer simulation is method applied to a ZCS buck QRC. A circuit implementation is presented that allows multiloop control to be used on circuits switching up to 10 MHz. This circuit requires few components and produces clean control waveforms. Experimental results are presented for zero-current flyback and zero-voltage buck QRCs, operating at up to 7 MHz. Good small-signal characteristics have been obtained. >

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W.A. Tabisz

Papers

Multi-loop control for quasi-resonant converters