Abstract：Aiming at the poor robustness and system vibration problem of asynchronous motors under the

traditional sliding mode control，a variability coefficient power exponent reaching law（VCPERL）was proposed to

dynamically change the control coefficients according to the position of the sliding mode surface，and the sliding

mode controller was designed based on this reaching law. Firstly，according to the advantages of quick-power

reaching law（QPRL）and the double-power reaching law（DPRL），which have different reaching rates at different

positions of the sliding mode surface，meanwhile，the tanh（x）was used to replace the sign（x），and a variable

coefficient was introduced into the reaching law. Secondly，the stability of the new reaching law was proved based

on theoretical analysis and simulation. Finally，the VCPERL was applied to design the sliding mode controller

according to the theory of vector control oriented by rotor magnetic chain and the dynamic mathematical model of

asynchronous motor. The simulation results show that compared with the traditional PI control，QPRL and DPRL，

VCPERL has strong immunity to load disturbances and fast recovery capability，which can effectively improve the

dynamic response performance of the system.

      Key words：asynchronous motors；new reaching law；sliding mode controller；convergence speed；disturbance carrying performance；dynamic response