This paper proposes a sensorless method for doubly salient electro‐magnetic motor (DSEM). The commutation signals are obtained through the comparison between the voltage of silent phase and a pre‐set threshold value based on the characteristic that the excitation back electromotive force (EBEMF) at commutation points is unaffected by the saturation of excitation field. Furthermore, in order to improve the torque output performance of DSEM, a novel sensorless advanced angle control (AAC) is investigated. Unlike traditional AAC, through piecewise linear fitting EBEMF in advance commutation interval, this method does not require the detection of standard commutation points. The experiments implemented on a 12/8‐pole DSEM validate the proposed methods over a wide range of speed and load conditions in both steady and dynamic procedures.

Owing to the merits of smaller voltage ripples, lower armature current and cost compared to full-control (FC), the angular position semi-control (APSC) scheme is proposed in this paper for low speed range of the doubly salient electro-magnetic generator (DSEG) operating over wide speed range, which improve the output voltage without increasing the field current. In APSC, the energy is stored with positive current in the inductance rising area and negative current in the inductance falling area, by which the output power and voltage increase, and the excitation current reduces. Moreover, in order to improve the poor dynamic performance resulting from the large storage capacitor required for APSC, an ideal output voltage model is established according to the ampere-second balance of the energy storage capacitor on the load side firstly. Secondly, several correction methods are investigated to enhance the accuracy of the ideal model. Finally, based on the conduction angle estimation model, a novel output voltage control strategy is put forward. The feasibility and superior dynamic performance of the proposed strategy are validated by the experiment results.

Torque ripples caused by the particular doubly salient structure of the doubly salient electromagnetic machine (DSEM) restrict its application in the field requiring high performance. This paper employs the current given function (CGF) to propose a torque ripple reduction strategy for DSEM to enhance the torque capability. The optimal current profile for minimizing the copper loss is obtained based on the theoretical analysis. It is found that the obtained three-phase currents are distributed according to the phase torque coefficient that represents the torque capability of each phase. Then, to minimize the torque ripple and copper loss, four CGFs are proposed to distribute the reference current of each phase according to the torque characteristics of DSEM. Finally, the influence of overlap angle on the proposed strategy is analyzed to select the reasonable CGF and overlap angle under different operating conditions through simulation, improving the current tracking performance and torque-ampere ratio. The simulation and experimental results demonstrate the effectiveness of the proposed strategy in suppressing torque ripple and improving the torque-ampere ratio.

This study first proposes a novel position sensorless control method for doubly salient electro‐magnetic motor (DSEM) based on line‐to‐line voltage. The commutation instants are estimated by comparing the proper line‐to‐line voltage with a commutation threshold value, which is preset according to motor speed and field current. Since only line‐voltage is required, the negative influence of DSEM neutral point voltage variation is eliminated. Moreover in addition, line‐to‐line voltage has a gain of phase back‐electromotive force (EMF), so the application speed range is desired to be extended. Then, the sensorless commutation lags introduced by reluctance back EMFs and low‐pass filters are analysed in detail, with the obtained mathematic expressions, a uniform compensation strategy by adjusting the commutation threshold value is proposed. With no need for extra hardware, the compensation strategy has the merit of easy implementation. What is more, to overcome the restriction of the distorted commutation signal arising in freewheeling process, a constraint of three‐phase currents is developed to avoid false commutation. Finally, the experiments on a 12/8‐pole DSEM validate the correctness and feasibility of the proposed techniques.

The controlled rectification method with positon sensor can effectively improve the output power of the doubly salient electromagnetic generator (DSEG), but weakens the advantage of no position sensor for the traditional DSEG with uncontrolled rectification. To solve this problem, a current self-injection based position sensorless control method is proposed for DSEG with H-bridge semi-controlled rectifier (HBSCR) in this article. Based on the operation principle of DSEG and HBSCR, the position estimation method is developed from the positive zero-crossing point of inductive electromotive force (EMF), which is indirectly observed through the test current self-injected by the inductive EMF. According to the relationship between generation current and test current, a test current self-injection method without presetting injection width is put forward, and the corresponding sensorless control strategy is established with the combination of angular position semi-control. Then, the compensation strategy is further presented to improve the accuracy of the proposed position estimation method. Finally, the simulations and experiments are implemented on a three-phase DSEG to validate the feasibility and correctness of the proposed sensorless control strategy.