Northern Telecom Limited

Chippower. Com, Inc.

Nortel Networks Corporation

Astec International Limited

Concordia University

Praveen K Jain

Yan-Fei Liu

Haibo Zhang

Gary Arthur Edwards

Harpreet Soin

Douglas R Bannard

Carl Hubbard

Simmi Mangat

Youhao Xi

A pulse width modulation control circuit for a high frequency series resonant AC/DC converter suitable for use in computing and network equipment such as personal computers, servers and high-speed routers includes an auxiliary transformer, a zero crossing detector, a delay circuit, a synchronization circuit and an output circuit.

Pulse with modulation control circuit for a high frequency series resonant AC/DC converter

A high-frequency resonant sine wave DC to AC inverter suitable for use in a personal computer (PC) power supply includes a full-bridge inverter, a resonant circuit, a phase shift modulation circuit, and a resonant gate driver. The resonant gate driver provides sinusoidal gate drive signals to the full-bridge inverter enabling highly efficient operation on the inverter.

High frequency DC to AC inverter

In a power factor corrected AC-to-DC power supply system, a DC-to-DC power converter is coupled to the output of an AC-to-DC power converter in order to produce a regulated DC output signal from a rectified AC input signal. The AC-to-DC power converter and the DC-to-DC power converter each includes a switch for controlling the operation of their respective power converter. The AC-to-DC converter includes an inductor. The system provides power factor correction for minimizing harmonic distortion by including a controller that receives the regulated DC output voltage as a feedback signal, and in response, produces a series of drive pulses having predetermined constant duty cycle. These pulses are simultaneously fed to each switch, to operate the respective converters alternately between ON and OFF states. When the AC-to-DC converter is driven by a fixed duty cycle of the series of pulses, power factor correction is improved since the current flowing through the inductor is substantially proportional to the waveform of the rectified AC input signal. By preselecting the value of the inductor, the AC-to-DC converter is operable in a discontinuous mode when the instantaneous rectified AC input signal is low and in a continuous mode when the instantaneous rectified AC input signal is high.

Topology and control method for power factor correction

An AC/DC converter for outputting high current, low voltage output from a high frequency AC source is described. The AC/DC converter includes two resonant components, a resonant circuit having a capacitor and an inductor. Both of the resonant components are connected in series and form a series resonant circuit. The converter further includes a transformer having a primary winding with a center tap to a secondary winding. The resonant circuit and the primary winding are connected in series. The center tap is connected to an output filter and a load, while the other two ends of the secondary winding are connected to two controlled switches, respectively. A drain of each of the two controlled switches is connected to opposite ends of the secondary winding, while each of the sources of the two controlled switches are interconnected. Two anti-parallel diodes are respectively connected across the two controlled switches. Two capacitors are also respectively connected across the two controlled switches. The on-time of the controlled switches is regulated to control the output voltage of the converter. The advantage is an inexpensive converter adapted to output high currents at low voltages with very little ripple and very low slew rate.

Single stage AC/DC converter high frequency AC distribution systems

An asymmetrical pulse width modulated resonant DC--DC converter exhibiting improved zero voltage switching characteristics is disclosed. The converter includes a chopper circuit to convert the DC input voltage to a high frequency AC voltage which, in turn, is fed to a high frequency transformer whose secondary AC is rectified and filtered to produce a stable DC output. A compensation network is placed between the input and the chopper circuit which provides zero voltage switching of the converter over a wide input voltage range.

Asymmetrical pulse width modulated resonant DC-DC converter with

A full bridge DC-DC converter has four switching devices in two switching legs each of two devices connected in series between two supply voltage terminals, junction points of the legs being connected to a primary winding of a transformer, from a secondary winding of which an output voltage of the converter is derived by rectifying and filtering. The output voltage is regulated by phase shift control of the switching devices. Zero voltage switching (ZVS) of the switching devices under potentially all converter load conditions is provided by snubber capacitors, connected in parallel with the switching devices, in conjunction with two inductors each connected between the junction point of a respective one of the switching legs and a point at a voltage midway between the voltages of the supply voltage terminals, which can be provided by a capacitive voltage divider between the supply voltage terminals. The inductors typically have different inductances, and one of the inductors may be omitted.

Full bridge DC-DC converters

A flyback converter has a main switch coupling a primary winding of a transformer between supply terminals, a duty cycle of the main switch controlling an output of the converter derived from a secondary winding of the transformer. Soft (zero voltage) switching of the main switch is facilitated by a snubber capacitor in parallel with the main switch. An auxiliary circuit coupled in parallel with the snubber capacitor and main switch includes a series-connected auxiliary switch, capacitor, and inductor coupled via another inductor to a full wave rectifier arrangement for recovering energy from the snubber capacitor. Resonant circuits provided by the auxiliary circuit facilitate soft switching of the auxiliary switch for low power loss and high frequency operation. The switches can be MOSFETs with reverse-poled diodes in parallel with their drain-source paths.

Flyback converter with soft switching using auxiliary switch and

Novel high frequency power distribution systems are disclosed. The system of the present invention uses a relatively high frequency AC (e.g. 100 kHz or higher) and distributes it by a high frequency bus which includes magnetic coupling. AC/DC converters are magnetically connected to the bus by way of associated magnetic coupling and rectify the AC to obtain DC power to be used by a respective load. The bus includes an inductive element which, in one embodiment, forms a series resonant circuit with a capacitive element of the AC/DC converter when it is magnetically connected to the bus.

High frequency power distribution system

Resonant DC/DC converters are disclosed. The DC/DC converters according to the present invention include a bridged inverter, a resonant circuit, a high frequency transformer and a rectifying circuit. The high frequency transformer has a tertiary winding. The resonant circuit consists of a series resonant branch connected to the transformer primary winding and a parallel resonant branch connected across the tertiary winding. The converters require less capacitive components and lend themselves well to miniaturization.

Tertiary side resonant DC/DC converter

A constant frequency full resonant mode dc/dc converter is provided, suitable for use in low voltage, high current dc power distribution systems. The converter comprises a full-bridge inverter, a resonant circuit, an output transformer, an output diode rectifier, a dc output filter, and a control circuit. The resonant circuit consists of a series branch and a parallel branch. The components of the series branch are selected such that close-to-maximum voltage gain and a near load independent output voltage of the converter are achieved. The components of the parallel branch are, however, chosen to obtain an overall lagging current at the output of the full-bridge for a desired range of output voltage control and no-load to full-load operating conditions.

Constant frequency resonant DC/DC converter

New topologies for pulse width modulated resonant DC/DC converters are disclosed. The converters include a bridged chopper to convert the DC input to a high frequency AC which in turn is fed to a high frequency transformer whose secondary AC is rectified and filtered to produce a stable DC output. The bridged chopper has at least two semiconductor switches which alternately conduct. The duty cycles of the conduction of the switches are complementary with one another and adjustable to control the stable DC output. A resonant circuit is connected between the chopper and the high frequency transformer and contains a series capacitor, and a series or parallel inductor depending upon the preferred embodiment.

Asymmetrical pulse width modulated resonant DC/DC converter

A constant frequency full resonant mode dc/dc converter is provided, suitable for use in low voltage, high current dc power distribution systems. The converter comprises a full-bridge inverter, a resonant circuit, an output transformer, an output diode rectifier, a dc output filter, and a control circuit. The resonant circuit consists of a series branch and a parallel branch. The components of the resonant circuit are selected such that a sinusoidal voltage waveform is achieved across the parallel branch, and an overall lagging current is obtained at the output of the full-bridge inverter for a desired range of output voltage control and no-load to full-load operating conditions.

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Kanata, Canada

Praveen K Jain