Forced commutation for fed current self controlled synchronous motor

Generally in speed drive applications, a voltage fed converters, using MOSFET and IGBT power components, are respectively used for low-medium and medium-high powers. In this paper, a current fed converter is considered for drive synchronous motor applications. This type of converters, that uses thyristors power components, is suitable for very large drives in very high powers, which is the aim future of this work. From this point of view, this paper aims to propose a proportional-integral controller for current fed self drive synchronous motor. Mainly a DC current loop to turn on and off thyristors, ensuring the forced commutation, is proposed to solve the problem of non existing back electromotive forces (natural commutation is not possible) when the motor operates at very low speeds. Simulation results show performances of the proposed method. Moreover, the proposed method is implemented by using both DSP and FPGA cards and first experimental results of the energy chain conversion (rectifier, inverter and synchronous motor) are obtained and presented.