Current control of a high speed SRM with an advanced 4-level converter

In this paper, a current control scheme is presented for high speed SRM (Switched Reluctance Motor) with an advanced 4-level converter. The presented 4-level converter for the high speed SRM has four current control modes which produces different 2 voltage levels during the sampling time. According to the current control modes, the average voltage of phase winding is different in the same PWM (Pulse Width Modulation) duty ratio. For the current ripple reduction, proper current control modes should be selected. In this paper, the boost voltage of the advance 4-level converter is automatically controlled as a set value without any auxiliary control signal, and the current control modes are automatically changed by the current error. The designed current controller can change the switching state according to the current error, the proper voltage level is supplied to the phase winding, and the phase current ripple can be reduced within the desired band. The detailed operating modes of an advanced 4-level converter and its current control scheme for the high speed SRM is described in this paper. And the proposed control method is verified by simulation which is compared with conventional current control method.