Two full-wave bridge rectifier circuits embodying the invention are disclosed. In each rectifier circuit four transistors and four sets of transformer windings for controlling base current are connected in a bridge configuration. Each transistor is connected in an inverted mode so that voltage blocking is performed by its collector-base junction. High efficiency is achieved by controlling the base current of each transistor in response to the emitter current thereof so that the base current is proportional to the emitter current so as to minimize circuit losses.
The present invention provides a synchronous full-wave AC rectifier connectable to an AC voltage source. In one embodiment, the synchronous rectifier includes a full-wave diode bridge having four bridge diodes. A power switch is coupled in parallel with each bridge diode, and each power switch has a power switch control gate. A power switch control circuit is coupled in parallel with each bridge diode. Each power switch control circuit provides a first control voltage to its associated power switch control gate to cause the power switch to turn on when the parallel-connected bridge diode is forward biased. Each power switch control circuit provides a second control voltage to its associated power switch control gate to cause the power switch to turn off when the parallel-connect bridge diode is reverse biased. The power switch control circuits turn their associated power switches on and off synchronously with the AC voltage source to provide the full-wave rectified AC output.
A DC power supply is disclosed. In one aspect, the DC power supply is a DC bias supply connectable to an AC source. The supply includes a first and second input node connectable to the AC source. A pump capacitor is provided having a first terminal coupled to the first input node and having a second terminal. A pump circuit is coupled between the second terminal of the pump capacitor and the second input node and having first and second output nodes. A storage capacitor is coupled between the output nodes, wherein during a first half-cycle of the AC source the pump circuit causes the pump capacitor accumulate a charge and during a second half-cycle of the AC source the pump circuit causes the pump capacitor to transfer to the storage capacitor the accumulated charge, thereby providing a rectified AC output voltage between the output nodes.
A synchronous power rectifier incorporating a bipolar power transistor operable in a switching mode to rectify the energy from a secondary winding of a power transformer. The synchronous rectifier reduces or eliminates the need of rectifier diodes, which provides power rectification without the power loss associated with the rectifier diode voltage drops. Moreover, the present invention includes further refinements of the circuit, including adjustment of the rectifier switching time to accommodate delayed turn-off times of bipolar power devices, and adjustment of the switching signal duration to provide output voltage regulation independent of the excitation of the transformer primary. The resulting embodiments of the present invention provide a modular switching power supply circuit of high efficiency, which may be operable together in combination to provide multiple output voltages.
In a rectifier circuit that rectifies an alternating current voltage generated by a generator and supplies the alternating current voltage to a capacitor as a power storage unit, a plurality of level shifters supplies a voltage level-shifted by an offset voltage to respective comparators when the comparators corresponding to transistors perform an on-and-off control, based on voltages across terminals of each of a plurality of transistors forming the rectifier circuit. The offset voltage is set accounting for a response delay time of each comparator. Each transistor is reliably turned off at the time the transistor should be turned off in relation to the voltage across the output terminals of the generator. As a result, a reverse current from the capacitor is thus prevented. A delay in the timing of turning off each transistor is eliminated.
A power converter nearly losslessly delivers energy and recovers energy from capacitors associated with controlled rectifiers in a secondary winding circuit, each controlled rectifier having a parallel uncontrolled rectifier. First and second primary switches in series with first and second primary windings, respectively, are turned on for a fixed duty cycle, each for approximately one half of the switching cycle. Switched transition times are short relative to the on-state and off-state times of the controlled rectifiers. The control inputs to the controlled rectifiers are cross-coupled from opposite secondary transformer windings.
