Multidomain Analysis and nth-Order Synchronous Reference Vector Adaptive Control of the Doubly Salient Motor

Due to the significant nonlinearity of the commutation of the square-wave current, the control of the doubly salient electromagnetic motor is hard to analyze quantitatively. This is because the present model is nonlinear and coupled. In this article, a linear decoupled model and symmetrical frequency shift cluster (SFSC) model are proposed based on a precise analysis of the time domain and complex-frequency domain. The results are extremely simple and mathematically computable. Moreover, these models focus on the average output torque, which is a key parameter at the same time. Furthermore, they explain well how torque ripple is generated. Based on the abovementioned results, a vector diagram of the harmonics of the phase current and inductance is proposed to precisely control the commutation in theory. Finally,
n
th-order synchronous reference vector adaptive control is proposed. The phase difference of each order is weighted to obtain the target function, which is proportional to the average output torque. The weighted phase difference is controlled adaptively to reach a maximum to realize the maximum torque per ampere. The theoretical results are verified by a 12/8 pole air-cooled prototype and related simulation and experimental results.