Application of Resolver in New Energy Electric Vehicles

The resolver, a critical component in new energy electric vehicles (NEEVs), plays a pivotal role in the drive motor system. This electromagnetic induction-based angle sensor is installed on the motor rotor shaft, functioning as the "eyes" of the electric vehicle's powertrain. Below is an in-depth introduction to the application of resolvers in NEEVs, presented in English.

The resolver consists of two main parts: the stator, which is stationary, and the rotor, which revolves and is attached to the motor shaft. The stator winding serves as the primary side of a transformer, receiving an excitation voltage. The rotor winding, acting as the secondary side, obtains an induced voltage through electromagnetic coupling. A high-frequency sine signal is transmitted to the stator primary winding, which is then transferred to the rotor winding. The stator and rotor windings work together like a transformer, with the rotor winding also referred to as the reference winding.

In NEEVs, resolvers are extensively used for position and speed feedback control of drive motors, ensuring efficient and precise motor operation. They provide high-precision rotor position feedback, assisting motor controllers (such as vector controllers or brushless DC motor controllers) in accurately regulating motor phase currents to optimize torque output and efficiency. This precise feedback also contributes to smooth acceleration and deceleration, enhancing vehicle handling performance and driving comfort.

Furthermore, resolvers can detect anomalies in the motor or control system, such as positioning errors or speed fluctuations, triggering protection mechanisms to prevent damage and improve system reliability. Their robustness against contamination, vibrations, and ability to operate safely within a wide temperature range makes them highly reliable and environmentally resistant, which is crucial in automotive powertrain systems.

Unlike encoders, resolvers have no electronic components, granting them a longer lifespan and superior durability, especially in harsh environments. They are also insensitive to electromagnetic interference, performing exceptionally well in high-EMI environments like NEEVs' high-voltage battery systems and high-frequency switching power supplies.

The resolver's output voltage maintains a specific functional relationship with the rotor angle, often in the form of sine, cosine, or linear functions, depending on the resolver's design parameters and wiring configurations. This relationship enables the resolver to measure the rotational angle of the rotating object by detecting the magnitude and direction of the induced electromotive force in the rotor winding.

In addition to measuring angular position, resolvers can also measure the angular velocity of rotating objects by continuously monitoring the rate of change of the induced electromotive force in the rotor winding. This measurement is crucial for achieving speed feedback and closed-loop control in motion control systems.

In summary, resolvers, as important sensors in NEEV drive motor systems, have become key components in the development of electric vehicle technology due to their high reliability and precise angle measurement capabilities in harsh environments. As technology advances, resolvers will continue to evolve towards higher precision, reliability, and intelligence, providing stronger support for the performance improvement and popularization of NEEVs.