Estimation of phase currents from a DC-link current sensor using space vector PWM method

The single-current sensor technique obtaining three phase currents from onl y a DC-link current sensor has been applied to reduce the cost and increase the reliability for various voltage-fed PWM inverters; however, in this te chnique there are some practical problems, such as unreliable detection of phase currents and phase shift. A new method that overcomes these problems by employing the estimation scheme with identified system parameters is pro posed. The Space Vector PWM (SVPWM) strategy is modified to generate the sw itching pattern, adequate for the proposed method. To obtain a good detecti on in spite of parameter uncertainties, system parameters used in the estim ation method are identified using a recursive feast square method (RLSM). E xperimental results show that the proposed scheme not only provides a very good detection method for three phase currents without current sensors, but also identifies system parameters very well. This proposed method is very simple, has a small detection error, and gives the information on system pa rameters.