Patent ID: 9041334
Filing Date: 2015-05-26
Classification: G05B,H02P

Abstract:
1. A control system for an electric motor, said control system comprising: a current sensing means arranged to produce a current sensing output indicative of electric current in said motor, current control means arranged to receive said current sensing output and to output a voltage demand indicative of voltages to be applied to said motor, and voltage demand correction means arranged to generate a correction signal and to use said correction signal and said voltage demand to produce a corrected voltage demand, wherein said voltage demand correction means is arranged to monitor the current sensing output thereby to measure distortion in the voltage demand, and to generate the correction signal so as at least partly to correct the distortion, said voltage demand correction means is arranged to identify a distortion frequency and identify a component of said current sensing output having a frequency equal to said distortion frequency, and to measure the magnitude of said component to measure said distortion, and said voltage demand correction means is arranged to transform said current sensing output so that said component becomes a DC component, and to measure the magnitude of said DC component.