Abstract: For the sensorless induction motor (IM) drive system, the second-order sliding-mode-based (SOSM) voltage model observer can effectively improve the robustness of speed estimation compared with the conventional open-loop voltage model observer. However, the existing SOSM-based voltage model observer still suffers from the problems of the following two aspects: 1) the mismatch problem between the fixed-value of SOSM observer gains and the variable stability condition; 2) the nonideal integrator problem due to the existence of dc offset. To cope with these two problems, this paper proposes the corresponding solutions: 1) to achieve wide-speed stability and chattering suppression, the SOSM observer structure is modified, and a variable gain is designed according to the stability condition; 2) to improve the accuracy of rotor flux estimation, an integrator with DC offset compensation is proposed based on the output of sliding-mode observer. Finally, the effectiveness of the proposed method is verified by the contrast experiments carried out on a 3.7 kW IM experimental setup.