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A zero voltage switching space vector modulation (ZVS-SVM) controlled three-phase boost rectifier is proposed. A branch composed of one active switch, one resonant inductor and one clamping capacitor is added to the six-switch boost rectifier. In addition, a ZVS-SVM for the rectifier is proposed. It can effectively suppress the reverse recovery process of the bridge switch anti-parallel diodes. All the switches are turned on under zero voltage condition, thus the switching loss is reduced, and electromagnetic interence can be lowered. The switching frequency of the rectifier is fixed. The auxiliary switch works at the same frequency with other switch. All the switches in the rectifier have lower voltage stress. A digital signal processor controlled 4-kW prototype is built to verify the theory. Index Terms--Electromagnetic interference (EMI), power factor correction (PFC), zero voltage switching space vector modulation (ZVS-SVM).

A classical model-based speed-sensorless field-oriented control method for a general-purpose induction machine is considered. Improved versions of both speed and stator resistance online estimators are presented with the aim of extending control capabilities down to zero speed. Only electrical stator measurements are needed, making the method suitable for general, purpose inverter applications. Online rotor resistance tuning is also included to fully compensate for thermal drift. Performance of the proposed drive is investigated by simulation and experiments. Index Terms--Induction motor, parameter tuning, speed estimation, speed sensorless, vector control.

A method for online estimation of the stator resistance of an induction machine is presented and a speed-sensorless field-oriented drive equipped with the proposed estimator is built. The drive is particularly suitable for low-speed operation. Resistance estimation is based on a two-time-scale approach, and the error between measured and observed current is used for parameter tuning. The simple full-order observer in use allows for direct field orientation in a wide range of operation. The system can drive active load and generate stall torque, as confirmed by numerical simulations and experimental tests on a general-purpose 7.5-kW induction machine. Index Terms--Induction motor, online tuning, sensorless, stator resistance, vector control.

A zero voltage switching space vector modulation (ZVS-SVM) controlled three-phase boost rectifier is proposed. A branch composed of one active switch, one resonant inductor and one clamping capacitor is added to the six-switch boost rectifier. In addition, a ZVS-SVM for the rectifier is proposed. It can effectively suppress the reverse recovery process of the bridge switch anti-parallel diodes. All the switches are turned on under zero voltage condition, thus the switching loss is reduced, and electromagnetic interence can be lowered. The switching frequency of the rectifier is fixed. The auxiliary switch works at the same frequency with other switch. All the switches in the rectifier have lower voltage stress. A digital signal processor controlled 4-kW prototype is built to verify the theory. [ABSTRACT FROM AUTHOR]

This article produces a simplified scheme in which the converter on the generator side controls both the reactive and real output powers without using the reactive power controller. The generator proposed in this article can be operated stably not only in steady state, but also in transient state. The induction generator is driven by a dc motor and these output power is converted to dc power, and dc power is converted to ac power of constant frequency through a separately excited inverter. The reactive power required for excitation of induction generator is supplied by the generator converter operating at control angle of advance.

An induction generator has been proposed that works stably over a wide-speed range. The only disadvantage of this generator is that a reactive power has to be supplied from a power source on the inverter side. This article proposes a means to solve the difficulty by connecting a dc chopper to the dc side of the inverter. The chopper works not only as a bypass circuit of dc current but also as a forced commutation circuit of inverter. A scheme is proposed to control the primary flux to keep the total efficiency maximum over wide ranges of generator speed and output power. In this case, the power factor of induction machine at low and output power level is also improved. A disadvantage of the proposed scheme is that the main circuit and the control circuit are a little complicated.