A Five-Phase Two-Machine Vector Controlled Induction Moto Drive Supplied from a Single Inverter

Abstract

SummaryTwo-motor drive systems, which require independent control of the two machines, are nowadays traditionally realised by using two three-phase voltage source inverters supplying independently two machines, paralleled to the common DC-link (Fig. 1). However, application of power electronics in electric drives enables utilisation of AC-machines with a phase number higher than three. If the number of phases is increased to five, an entirely different solution for the realisation of a two-motor drive system becomes feasible. It is shown in the paper that an increase of the stator phase number to five enables completely independent vector control of two five-phase machines that are supplied from a single current-controlled voltage source inverter. In order to achieve such an independent control it is necessary to connect five-phase stator windings of the two machines in series and perform an appropriate phase sequence transposition (Fig. 2). The concept is equally applicable to any five-phase AC machine type and its major advantage, compared with an equivalent two-motor three-phase drive, is the saving of one inverter leg. Instead of six inverter legs, only five are required. Detailed verification of the novel five-phase two-motor drive configuration is provided by simulating the operation in the torque and speed mode, using indirect rotor flux oriented control principles. The concept can be extended to higher number of phases in a simple manner. Its main advantages and drawbacks are addressed as well.