A precise detection of the fault feature parameter of motor current is a new research hotspot in the broken rotor bar (BRB) fault diagnosis of induction motors.Discrete Fourier transform (DFT) is the most popular technique in this field,owing to low computation and easy realization.However,its accuracy is often limited by the data window length,spectral leakage,fence effect,etc.Therefore,a new detection method based on a global optimization algorithm is proposed.First,a BRB fault current model and a residual error function are designed to transform the fault parameter detection problem into a nonlinear least-square problem.Because this optimization problem has a great number of local optima and needs to be resolved rapidly and accurately,a joint algorithm (called TR-MBPSO) based on a modified bare-bones particle swarm optimization (BPSO) and trust region (TR) is subsequently proposed.In the TR-MBPSO,a reinitialization strategy of inactive particle is introduced to the BPSO to enhance the swarm diversity and global search ability.Meanwhile,theTR is combined with the modified BPSO to improve convergence speed and accuracy.It also includes a global convergence analysis,whose result proves that the TR-MBPSO can converge to the global optimum with the probability of 1.Both simulations and experiments are conducted,and the results indicate that the proposed detection method not only has high accuracy of parameter estimation with short-time data window,e.g.,the magnitude and frequency precision of the fault-related components reaches 10-4,but also overcomes the impacts of spectral leakage and non-integer-period sampling.The proposed research provides a new BRB detection method,which has enough precision to extract the parameters of the fault feature components.