Patent ID: 7558083
Filing Date: 2009-07-07
Classification: H02M,Y02B

Abstract:
1. A non-regulating isolating step-down DC-DC power converter that provides a non-regulated, isolated DC output having a non-regulated voltage, comprising: i) at least one isolating step-down transformer that is not driven into saturation, the at least one transformer having plural windings including at least one primary winding and at least one secondary winding; ii) plural power MOSFET switches in circuit with the at least one primary winding, the plural power MOSFET switches causing power from a DC input to flow into the at least one primary winding; iii) control circuitry coupled to the plural power MOSFET switches, the control circuitry determining when the power MOSFET switches are turned on and off in a switching cycle at a switching frequency, the switching cycle substantially comprising two substantial portions, a first portion and a second portion; and iv) plural controlled rectifiers in circuit with the at least one secondary winding, each having a parallel uncontrolled rectifier, each controlled rectifier being turned on for an on-state time and off for an off-state time in synchronization with a voltage waveform of the at least one primary winding to provide the non-regulated, isolated DC output having a non-regulated voltage, the voltage waveform of the at least one primary winding having a fixed duty cycle and transition times which are short relative to the on-state and the off-state times of the controlled rectifiers; v) a first controlled rectifier of the plural controlled rectifiers being conductive during the first portion of the switching cycle and a second controlled rectifier of the plural controlled rectifiers being conductive during the second portion of the switching cycle, there being a short time, during a transition between the portions, when the first controlled rectifier and the second controlled rectifier are both off and their corresponding uncontrolled rectifiers are both conducting.