Improved PWM Control With Wide Speed Range for a Double-Side Asynchronous Rotor AFPMM Series-End Winding Drive

Robot dogs are welcomed widely in industry and daily life. To reduce the volume and weight of robot dogs, a double-side asynchronous rotor axial-flux permanent magnet machine is designed for them. It has two asynchronous rotors on two sides which are driven respectively by two sets of windings, so the control of the machine is different from that of conventional machines. Thus, an improved pulsewidth modulation (PWM) control is proposed for the machine. In the control, the two sets of three-phase windings are connected in series, so there are seven legs in the drive. Compared with two separate conventional series-end winding (SEW) drives for two sides, the proposed SEW serves as a reduced-switch-count topology. Besides, it guarantees wide speed ranges for the dual rotors of the machine. Due to the overmodulation, zero sequence component (ZSC) optimization is conducted for the drive. The control scheme adopts an optimal ZSC for the dual windings with the consideration of both reference voltages of two sides. The experiment validates that the proposed improved PWM control gets better permanence compared with other methods.