Study on Sliding Mode Control of Permanent Magnet Synchronous Motor with Improved Convergence Law

A new convergence law is designed to address the problems of large jitter and slow convergence speed of the traditional convergence law control scheme for permanent magnet synchronous motors. The novel convergence law introduces a system error variable, replaces the switching function with a smooth saturation function, then replaces the exponential term using the novel function, and adds a hyperbolic tangent function to limit the function amplitude. First, a theoretical verification of the convergence law is performed. Then, the integral sliding surface is constructed by combining the integral terms, and the new speed controller is designed. Finally, simulation is performed to verify. The simulation results show that the new convergence law sliding mode control has small jitter, no overshoot and high robustness compared with the traditional convergence law.