一种减小变频空调压缩机低速范围内转速脉动的方法

A New Method to Reduce the Periodic Speed Ripples of Air-Conditioners in Low Speed Range

近年来,永磁同步电机因其固有优点在空调压缩机中得到了广泛的应用。但常用的永磁同步电机?单转子式压缩机系统,由于工作条件的限制,无法安装位置编码器,受位置估算精度的制约,一般采用方波驱动,必然导致电机本身输出转矩脉动偏大。同时,在每个机械周期内,压缩机负载脉动非常剧烈,也造成整个系统低速运行时转速脉动大,噪声高,效率降低。本文将模型参考自适应方法推广到凸极永磁同步电机中,对电机转速和转子位置进行准确估算,实现了正弦波矢量控制。针对空调压缩机脉动负载,定义了机械周期内电磁转矩对位置积分的能量函数,有效地估算出当前负载状况,并通过查表法获得估算的负载转矩。然后根据估算的转子位置对负载脉动转矩进行转矩电流前馈补偿,显著降低了压缩机低频噪声和振动。仿真和实验结果验证了本文所提方法的有效性和实用性。

Recently, permanent magnetic synchronous motors（PMSM） are widely used in household appliance. For a common PMSM-Single Rotator Compressor system, encoder is not used because of the limitation of the working environment. The vibration of the compressor during each mechanical period is serious due to the pulsating load torque in low speed range and the ripple of the motor output torque caused by square wave driving method. In this paper, a speed estimation method based on model reference adaptive system（MRAS） is extended to a interior PMSM. With the speed and position obtained, vector control of the interior PMSM is realized. A new energy function is defined to estimate the load condition. According to the energy function, the load torque can be estimated by a look-up table. Then a feedforward compensation of load torque current is utilized to reduce the speed ripple caused by the pulsating load torque. Simulation and experiment results prove the effectiveness of the proposed method.