Single sensor current control of a multiple phase AC machine

摘要

An improved digital PWM closed-loop current control for a multiple phase winding AC machine which requires only a single sensor for monitoring the current in one of the phase windings of the machine. The PWM on-time values for the various phase windings of the machine are stored in a single look-up table as a function of stator position and requested current amplitude, and the on-times used to schedule phase winding energization are periodically updated using a two-part look-up procedure. Initially, the stored on-time value for a single phase winding is retrieved from the table as a function of stator position and the requested current amplitude. The retrieved value is then compared with a measure of the actual current in the respective phase winding to form an error signal, which is used to adjust the requested current amplitude. The requested current amplitude, as adjusted, is then used, along with the stator position, as a table look-up parameter to retrieve PWM on-times for all three phase windings, thereby automatically adjusting multiple phase winding currents in a balanced fashion.