基于相关性相位提取的超声电机频率控制技术

为了解决温度和负载的变化容易引起超声电机转速波动,以及基于转速反馈的闭环控制因转速传感器安装体积和成本在某些特种场合应用受限的问题,提出一种基于相位差信息反馈的频率闭环控制方法:首先,根据电机各类相位差对温度和负载变化的敏感程度,优化选择了相位差反馈量的类型;其次,针对系统机械噪声以及驱动器谐波对相位差计算结果的影响,利用改进的相关性相位提取方法准确提取驱动电压和孤极电压的基频相位差信息;最后,分别就超声电机运行过程中温度和负载变化的情况,给出了相应的频率闭环控制方案。实验结果表明,所提出的方法能有效降低温度以及负载变化导致的转速波动,可提升电机所在系统的转速稳定性。由于其只需采样两路电压信号,故易于工程实现。

Frequency control technology for ultrasonic motor based on correlation phase extraction method

In order to solve the problems that the speed of ultrasonic motor is usually affected by the changes of temperature and load, and that due to installation volume and cost of the speed sensor, the closed-loop control based on speed feedback is often limited in some special applications, a frequency closed-loop control method based on phase difference feedback is introduced. Firstly, the type of phase difference feedback quantity is optimally selected according to the sensitivity of different motor phase differences to the temperature and load change; secondly, aiming to the interference of mechanical and harmonic noises on phase difference calculating result, the correlation phase extraction method is proposed to improve the accuracy of phase difference between driving voltage and monitor electrode voltage; lastly, the corresponding frequency closed-loop control scheme is given according to the changes of temperature and load change, respectively. Experiment results indicate that this method can reduce the speed fluctuations caused by the changes of temperature and load, and improve the speed stability of motor system. Because only two voltage signals are needed to be recorded, this method is easy for implementation.