Rotor Position Sensing via PWM Timing to Suppress Eddy Currents

The method applies preliminary action by intentionally injecting high-frequency voltages into the machine windings before measuring phase currents. This preliminary voltage injection creates a controlled current change that enhances the anisotropy effect, allowing the rotor position to be determined with sufficient precision even in the presence of eddy currents. The high-frequency voltage injection is performed at specific timing relative to the PWM switching cycles to optimize the measurement conditions.

The method employs parameter changes by varying the frequency and amplitude of injected voltages, and by selecting optimal measurement timing parameters. Specifically, the system changes the operating parameters of the high-frequency voltage injection (frequency, amplitude, timing) to maximize the current change signal while minimizing the impact of eddy currents and temperature effects on measurement precision.

The method converts the harmful effect of eddy currents into a beneficial measurement opportunity. By intentionally injecting high-frequency voltages at specific timing, the system creates controlled eddy currents that decay at predictable rates. The measurement is performed during the decay phase, where the eddy current signature provides information about rotor position while the magnitude of eddy currents is reduced compared to continuous injection. This transforms the normally harmful eddy current effect into a useful signal source.

The method applies periodic action by injecting high-frequency voltages in periodic pulses synchronized with the PWM switching cycles rather than continuously. This periodic injection allows eddy currents to decay between injection pulses, reducing their cumulative harmful effect. The systematic timing of voltage injection and current measurement creates a periodic measurement cycle that optimizes the signal-to-noise ratio while minimizing eddy current interference.

The method applies preliminary anti-action by pre-calculating and storing temperature compensation parameters and optimal measurement timing tables before operation. Based on anticipated temperature ranges and machine characteristics, the system pre-determines the optimal measurement moments and compensation factors. During operation, these pre-computed parameters are applied to counteract temperature effects without requiring complex real-time calculations, thus maintaining both measurement precision and operational simplicity.

The method employs feedback by using the measured phase currents and determined rotor position to continuously update and refine temperature compensation parameters. The system monitors the relationship between measured currents, rotor position, and temperature, and adjusts the compensation algorithm accordingly. This feedback mechanism allows the system to adapt to changing temperature conditions while maintaining measurement precision and operational flexibility.