Mechanical rectifier

Abstract: Apparatus and method for eliminating cross conduction of self-driven synchronous rectifiers in power converters caused by non-idealized ringing of parasitic capacitances and inductors. In an exemplary embodiment, the apparatus includes synchronous rectifiers or some hybrid topology having at least one synchronous rectifier coupled to a damping circuit having at least one switching device. The switching device is activated (ON) at a time when at least one of the synchronous rectifiers is supposed to remain inactive (OFF). Accordingly, when the switching device is ON, the device effectively dampens any ringing present at the synchronous rectifier that may cause the rectifier to inappropriately transition ON. The damping circuit of the present invention utilizes the same signals present to control the synchronous rectifier(s) and requires no additional control circuitry. Additionally, the damping circuit dramatically improves the efficiency of self synchronous power converters and is topology independent.

Abstract: This paper describes a technique for shaping the input current to a three-phase diode rectifier using a two-switch series-connected dual boost converter and a three-phase bidirectional switch circuit. Circuits are described for generating a single voltage DC output, "single DC-rail", or a dual output DC voltage using center-tapped capacitors, "split DC-rail". Both rectifier types can be operated with the boost inductors located either on the DC or the AC side of the rectifier. The resultant rectifier circuit configurations have an excellent immunity to the "shoot-through" fault condition and use active switching elements with low per-unit current ratings and low switching losses. These features increase the reliability factor and lower the cost penalty associated with unity fundamental power factor three-phase rectifiers. Test results are presented for the rectifiers using simulation and experimental results.

Abstract: A simple and robust 24-pulse diode rectifier for low-voltage and high-current applications is proposed in this paper. The proposed 24-pulse diode rectifier consists of a conventional four-star 12-pulse diode rectifier and an auxiliary single-phase full-wave rectifier (ASFR) installed at dc side. The low-power (3.4%Po) ASFR extracts two rectangular currents from the modified second-stage interphase transformer and injects a square current into the output of the rectifier system. This modification extends the conventional four-star 12-pulse operation to 24-pulse operation. The proposed 24-pulse rectifier draws near sinusoidal input line currents with the absence of 5th, 7th, 11th, 13th, 17th, and 19th harmonics. The average value of current through the ASFR has only 1.7% of load current, which means the current rating and conduction losses of ASFR are very small. The proposed scheme has low-diode conduction losses, and it is more suitable for low-voltage and large-current applications. Since only an additional ASFR is needed, the proposed scheme is low cost and simple to implement. The detailed analysis for the proposed rectifier is presented, and experimental results are provided to verify the proposed concept.

Abstract: A number of class-E, half-wave and full-wave, zero-voltage-switching (low dv/dt), zero-current-switching (low di/dt), and mixed-mode rectifiers are introduced and verified experimentally. The rectifiers are derived from conventional rectifiers by adding reactive components. New conventional rectifiers are also introduced and presented in a systematic manner. The principle of class-E rectifier operation is explained using current and voltage waveforms. The class-E rectifiers offer a means of rectification suitable for high-frequency applications, e.g. in resonant DC/DC power converters. A general approach to the synthesis of resonant DC/DC converters is presented. >