###### Abstract  
In order to improve the performance of motor drive systems, this paper introduces a sensorless control method for interior permanent magnet synchronous motors (IPMSM) based on the rotating high-frequency voltage injection method. The demodulation method using a synchronous frequency filter (SFF) instead of a bandpass filter (BPF) and a high pass filter (HPF) is proposed. The structure and transfer function of SFFs are introduced, and their characteristics are simulated and analyzed. Therefore, the center frequency of SFFs can be adaptively adjusted according to the estimated rotational speed, which is convenient for frequency setting. Finally, according to the proposed rotating high-frequency voltage injection method, the simulation model is built. The experimental results verify that the control strategy can maintain good position estimation accuracy, better speed tracking performance and anti-load disturbance performance.  
interior permanent magnet synchronous motor; position sensorless control; rotating high-frequency voltage injection method; synchronous frequency filter +
Footnote †: journal: Applied  
current injection method according to the type of injection signal. According to the different reference systems and signal forms of high-frequency injections, the existing high-frequency voltage injection methods mainly include the rotating high-frequency voltage injection method in the two-phase stationary coordinate system and a pulse high-frequency injection method in the axis of the estimated two-phase rotating coordinate system. BPFs and HPFs are utilized in the signal extraction process of the traditional high-frequency signal injection method. The frequency of the motor system changes with the speed, and the cut-off frequency or the center frequency of the filters is fixed. Therefore, it is a challenge to reduce the impact of speed changes on filtering performance. In reference [20], the method of injecting two bidirectional rotating high-frequency carrier signals is utilized to improve the rotor position estimation accuracy. Four equations are constructed. In reference [26], the active disturbance rejection control strategy is used to estimate and compensate for the total disturbance of the system and improve the dynamic performance of the system. Reference [27] adopts an enhanced linear active disturbance rejection control method to compensate for the total disturbance in a feed-forward manner. Reference [28] utilizes recursive discrete Fourier transform to demodulate and collect signals, and the method can reduce the influence of a low-pass filter. Reference [29] introduces a high-frequency pulse voltage injection method, which uses a quasi-resonant controller to replace a low-pass filter to improve the dynamic performance of the system.  
The main purpose of this paper is to propose a rotating high-frequency voltage injection method for IPMSM. The demodulation method, using an SFF instead of a BPF and an HPF, is utilized to extract the signal. The structure and transfer function of SFFs are introduced, and their characteristics are simulated and analyzed. It can be seen from the structure and transfer function that the center frequency of SFFs can be adaptively adjusted. Therefore, the center frequency setting is more convenient. In addition, the motor drive system can maintain good position estimation accuracy, speed tracking, and anti-load disturbance performance due to the frequency adaptive function. Finally, the simulation model of the sensorless control IPMSM system is built, and the correctness and effectiveness of the control strategy are verified using the simulation results.