Abstract: The present invention is directed to a circuit for reversing the polarity of a high voltage power supply. Circuits according to embodiments of the invention may include four switches, one or more of which may be solid-state switches. The solid-state switches may include a transistor stack that is supplied a biasing voltage in response to the receipt or removal of a control signal. When the biasing voltage is supplied to one transistor in the stack to change it to the closed or “ON” state, the other transistors in the stack may also be changed to the closed state in a cascading process. The control signal may be a low voltage signal and may be isolated from the solid-state switch by a control switch, which may be an optocoupler.

Abstract: Embodiments of the present invention are directed to a high voltage shunt regulator. The shunt regulator may receive input power of positive or negative polarity and may have two conduction paths. A conduction path may be engaged when the input power is of the proper polarity and the output voltage (or some other characteristic to be regulated) does not match a desired value. The conduction path may include a solid-state shunt in the form of a transistor stack. In embodiments of the invention, the transistor stack includes a number of serially-connected bipolar junction transistors (BJTs), one of which may be operated in the linear region and others of which may be either saturated or in the off state. Voltage regulators may be provided in each stage of the transistor stack to prevent excessive voltage from being applied across the terminals of a corresponding transistor and to provide a shunt path for current when the corresponding transistor is in the off state.

Abstract: A power supply for achieving high output power levels at a high efficiency from a compact profile. The power supply includes a current regulator which receives a source voltage and outputs a signal having a constant current. The signal output from the regulator is provided to a center tap of a primary winding of a transformer. The ends of the primary winding of the transformer are connected to switches which are controlled by a switch driver. The transformer, switches and switch driver form a resonant oscillator. The switch driver is connected to a zero voltage level detector which detects when the voltage of the signal output from the current regulator reaches a zero level. When such a detection is made, the zero voltage level detector provides an enable signal to the switch driver to operate the switches in a push-pull mode. By operating the switches in a push-pull mode, the energy balance and resonance of the transformer can be maintained.