Due to the nonlinear saturation and high thrust force ripples in linear vernier permanent-magnet motor drive, an improved direct thrust force control strategy based on the anti-windup PI controller and duty ratio modulation is proposed.The variable-structure is adopted in the proposed controller, which can make the system quickly exit saturation zone. Duty ratio modulation with a constant switching frequency is adopted based on the analysis of effects that voltage vector has on thrust force ripples in the control strategy. The simulation and experimental results show that the proposed improved direct thrust force control system can effectively reduce the systemic overshoot and thrust ripples, thus improving the stability and robustness of the control system.

This paper proposed a new fault-tolerant direct thrust force control (DTFC) for a dual inverter fed open-end winding linear vernier permanent-magnet (LVPM) motor. First, the topology and structural characteristics are briefly presented. Second, the mathematical model of the LVPM motor is derived. Then, a new fault-tolerant DTFC is proposed, in which inverter fed open-end winding technique is adopted. When inverter switch fault occurs in open-end winding driving system, the connection point between the motor port and the fault switch is cut off, and motor port is connected to power source neutral point. An improved space vector pulse width modulation is reconfigured by the rest of switches to implement DTFC. Finally, experimented results are given to verify the proposed fault-tolerant control strategy.

The linear vernier permanent-magnet (LVPM) motor incorporates the merits of high efficiency and low cost, which is very suitable for long stroke applications. This paper proposed a new direct thrust force control for dual inverter fed open-end winding LVPM motor to reduce force ripple. First, the topology and structural characteristics of the LVPM motor are briefly presented. Second, the mathematic model of the LVPM motor is derived. Then, a new direct thrust force control based on dual inverter fed open-end winding technique is proposed. The open-end winding drive is obtained by connecting six windings terminal of the LVPM motor to dual inverter respectively, which provides greater numbers of voltage vector and higher classes of output voltage to improve control performance. An improved space vector pulse width modulation based on dual inverter is configured to minimize force and flux ripples, which results constant switching frequency of operation. Finally, the simulation results are given to verify well steady-state and dynamic performances of the proposed control strategy.