A Three Phase Sine Wave Reference Generator For Thyrisitorised Motor Controllers

A variable frequency, variable amplitude three-phase low frequency sine wave reference generator is discussed in this paper. The frequency and amplitude are independently capable of being varied by means of two independent dc control voltages. This reference generator is well suited for closed loop control applications such as constant frequency power supplies, constant amplitude power supplies, induction motor control requiring a finite ratio between amplitude and frequency, etc. The reversal of polarity of the dc voltage controlling the frequency reverses the phase sequence. The reference generator has been very satisfactorily used in the control of a three-phase ``subharmonic'' pulse width modulated inverter. The reference generator is also suitable for cycloconverter control.