Novel control scheme for adjustable speed synchronous machine drives

Abstract

Adjustable speed synchronous machine drive has been established as the high quality drive. Unity power factor control of the machine is expected to be of higher efficiency for the machine and for the inverter. The only method now existing is to feedback control the phase angle between input voltage and current to be zero.The control procedure is complex. This paper reports a newly developed forward control scheme for unity power factor control of the synchronous machine. Simulation shows good performance of the scheme. Key words: synchronous machine, unity power factor control, IPM-SM, MT-axes control power factor control has been developed. At first, it is necessary to display the voltage and current of the machine in a single coordinates with equally defined quantities. To achieve the aim, the vector diagram of the machine has been displayed with normalized voltage and normalized current quantities. Then, the conditional equation for unity power-factor control can be deduced. According to the equation of unity power-factor as well as the well-known equation of maximum torque-efficiency, a novel control scheme for the synchronous machine has been researched and proposed, in comparing with the so far existing MTaxes control method. As the example machine, an IPM-SM has been used. The simulation of the scheme has shown good performance.