PWM Modulation Strategy for Common Mode Voltage reduction in five-phase machines

Abstract

The three-phase machine is the most used, but alternating current machines with a number of phases greater than three have advantages over three-phase machines, such as extra degrees of freedom in the drive system; increase in useful torque by effective current value; among others. Static converters used to drive the machine introduce high frequency voltage components, which find a low impedance path to ground through the stray capacitances of the machine. Among the associated problems, mechanical failures in the bearings can be mentioned; increased levels of electromagnetic emissions; among others. A reduction in these problems can be achieved by reducing the common mode voltage in the drive system, as this is the voltage that powers the parasitic circuits of the machine. Among the solutions proposed in the literature for common mode voltage reduction and eddy current circulation, one can mention the use of passive filters associated with the inverter topology and/or the use of appropriate PWM modulation strategies. In this paper a new space vector modulation PWM (SVPWM) technique is presented to reduce common mode voltage for five-phase machines.