Improved Field-Weakening Control of PM Motors for Home Appliances Excluding Speed Loop Windup

Field-weakening (FW) operating mode is an essential function of high-performance permanent magnet (PM) motor drives, which helps to overcome limitation of speed due to the lack of input voltage, thus increasing drives’ speed operational region. Therefore, one of the algorithms for FW is a crucial part of the overwhelmingness majority of PM motor control systems. The most popular FW approach is a feedback technique, however it is computationally intensive and may demonstrate speed loop windup. In order to eliminate abovementioned disadvantages, this article proposes optimization for fast computing of FW controller and modifications to the conventional feedback FW controller, which exclude speed loop windup. The suggested optimizations exclude square root calculations and decrease computational cycles ten times. The proposed antiwindup technique dynamically recalculates limits for speed controller, considering FW current calculated by the FW controller. These improvements provide speed loop antiwindup operation, simplify structure of the resulting control scheme, decreases system reaction time and computational burden on the microcontrollers, which is extremely important to low-cost motor drives.