Low‐Speed Sensorless Control of Induction Motors Using Silicon Carbide (SiC) Inverters

Current research on sensorless control for induction motors (IMs) with silicon inverters shows inadequate performance at low speeds. However, there is no reported literature on the influence of silicon carbide (SiC) device characteristics on the performance of IM sensorless control for model‐based methods, and the influence remains unclear. This article addresses this gap by demonstrating an IM sensorless control system with SiC inverters and investigating its speed estimation accuracy under low‐speed conditions. Firstly, the mechanism relationship between SiC device characteristics and speed estimation accuracy is revealed to reduce estimation error. Further, a three‐level adaptive compensation method, considering non‐ideal factors, such as the electromagnetic interference caused by high dv/dt of SiC devices and the parasitic capacitance effect, is proposed to improve the speed estimation accuracy. As a result, the low‐speed operating range is extended to 15 rpm (0.5 Hz), and the speed error is below 5 rpm in dynamic and static conditions of the speed from 30 to 60 rpm, which is verified on a 7.5 kW IM drive platform based on the SiC inverter.