A High-efficiency Resonant Driver and Soft Decoder Interface with Fast-dynamics PLL-Type Angle and Speed Tracking Observer for Resolvers

Reliable and robust sensored motor control demands accurate and consistent measurement of position and speed of the motor shaft. Resolvers are robust and precise analog position transducers that require a sinusoidal excitation voltage with specific amplitude and frequency. Because of that, it is not usually possible to excite the resolver directly from a microcontroller, often used for motor control applications. This paper presents a new resonant, high-efficiency resolver excitation circuit, which guarantees a high-density layout with minimal component usage. The optimization process of the circuit design is presented. The network is coupled with a novel soft fast-dynamics PLL-type angle tracking observer, to extract angle and speed information. Simulation and experimental results demonstrate that the presented interface is effective, showing less than 2% THD and efficiency increase up to 5× (design-dependent) when compared to a traditional class AB driver.