Multilevel PWM rectifier-multilevel inverter cascade. Application to the speed control of the PMSM

This paper studies the control of the multilevel PWM rectifier-multilevel inverter permanent magnet synchronous machine (PMSM) cascade. We present the field oriented speed control of the PMSM, and develop the control model of the three-level inverters by using the generating functions. We propose a new calculated strategy of the inverter which uses its control model. We show the problem of the middle point of the inverter input DC voltage source. A solution to this problem is to control this input DC voltage and then the potential of its middle point by a feedback control of the three-level PWM rectifier. Thus, we present a control loop of these three-level PWM rectifiers in order to control the input DC voltage of the inverters and the current in the network. This drive system finds applications in high power and high speed drive fields such as the electric traction.