Using multiple saliencies for the estimation of flux, position, and velocity in AC machines

Abstract

Abstract-This paper presents an improved method of estimating flux angle, rotor position, and velocity by tracking the position of spatial saliencies in an ac machine. Specifically, a machine model is presented which accurately models the behavior of ac machines with multiple spatial harmonic saliencies. The effects of multiple spatial harmonic saliencies on the estimation of flux angle, position, and velocity is analyzed, and methods are presented utilizing multiple spatial harmonic saliencies to provide wide bandwidth, high accuracy estimates of flux angle, rotor position, and velocity.

Load invariant sensorless control of a SRM drive using high frequency signal injection

“…However, the low-pass filter used to extract the dominant spatial saliency attenuates this adverse effect of the secondary saliency as the rotor speed increases from zero speed. The secondary saliency could also be decoupled [13], allowing the low-pass filter bandwidth to be increased.…”

“…These methods can be divided into two categories: those that use only the fundamental signals in the machine [6][7][8][9][10][11] and those that inject additional signal into the machine to estimate the rotor position [12][13][14]. For the first case, the methods degrade at low speed because the frequency of the electrical signals is low.…”

“…Another disadvantage is that additional hardware is required to inject the high frequency signal. In [13], a carrier frequency rotating vector excitation is injected to the SRM and a tracking observer is used to estimate the rotor position based on the machine saliency. This method does not require any additional hardware and is less sensitive to parameter errors.…”

“…In this paper, the sensorless control methods of [13][14] are extended so that load invariant sensorless control of the SRM is possible. In order for these techniques to be applicable, the main excitation current and carrier frequency signal must be separated.…”

“…The choice of which harmonic to track depends on both the magnitude and harmonic number of the saliency. In theory, it is better to track the signal that has the largest product of magnitude and harmonic number [13]. However, one must take the signal-to-noise ratio of the signal into consideration as well.…”