Very fast phase angle estimation algorithm for a single-phase system having sudden phase angle jumps

This work proposes a very fast phase angle estimation algorithm for a single-phase system under a sudden phase angle jump condition. When a source voltage changes in a step manner, the normal phase angle detector, such as a phase locked loop (PLL) and a (low pass) filter, typically generates phase delay and results in a sluggish response, and causes some time-critical machine to malfunction. This work proposes a method of estimating the fundamental component, the phase angle and the frequency of a single-phase line voltage without a significant delay, even when the amplitude and the phase angle of the line voltage changes in a step manner, by using the weighted least-squares estimation (WLSE) method with the covariance resetting technique. An example application of a single-phase pulse width modulation (PWM) rectifier for a traction is presented in an appendix. This method can be applied to uninterruptable power supply (UPS), PWM rectifier, active filters, etc.