Dynamic Direct Voltage Control Under Maximum Torque per Ampere for Interior PMSMs

A novel method for controlling the speed of interior permanent magnet synchronous motors (IPMSMs), known as the current-sensing-based dynamic direct voltage control method under the maximum torque per ampere (MTPA) concept, is introduced. This technique achieves precise tracking of machine velocity by determining the optimal combination of voltage amplitude and angle for each specific motor velocity and current/load condition. Unlike previous studies, this approach takes into account the transient model of the machine, resulting in improved accuracy during dynamic operating conditions compared with existing methods in the literature. Moreover, a comparative analysis is conducted involving different direct voltage MTPA speed drive approaches: the current-sensing dynamic direct voltage control (CS-DDVC) methodology, the simplified DDVC technique, and the static direct voltage MTPA control strategy. The well-known field-oriented control method is also included in the analysis. The dynamic methodology employs two tuning parameters to achieve the same MTPA objective while eliminating transient effects. Experimental results and quantitative assessment demonstrate that the proposed MTPA control methodology is a highly effective strategy, offering a respectable alternative to existing MTPA methods for driving IPMSMs. It enables the operation of IPMSMs under MTPA working conditions with high efficiency, making it suitable for a wide range of industrial applications. Experimental results demonstrate a reduction in speed dip from 120 rpm to 50 rpm at full load application and a 128% improvement in IAE compared to conventional DVC. From an engineering design perspective, the proposed control framework simplifies the drive-system architecture by eliminating cascaded current-control loops while maintaining effective transient dynamic performance suitable for embedded electric vehicle applications.