Three-Phase Motor Driver Using Linear Signal for BEMF Detection

The patent applies periodic action by using pulse width modulation (PWM) to generate modulated signals for driving the three-phase motor. The PWM technique periodically switches the power delivery to the motor windings, creating a series of pulses with varying widths that correspond to the desired motor control. This periodic switching enables precise control of motor speed and torque while maintaining efficient power delivery, directly addressing the contradiction by implementing structured periodic action to achieve both performance improvement and controlled noise generation.

The patent applies parameter changes by dynamically adjusting the pulse width (duty cycle) of the PWM signals to control motor operation. By varying the width of each pulse while maintaining a fixed frequency, the system can precisely control the average power delivered to the motor windings. This parameter adjustment mechanism allows the system to optimize motor performance across different operating conditions while managing the noise and errors associated with the switching action.

The patent applies the intermediary principle by introducing a high-impedance sensing leg that acts as a mediator between the PWM driving circuit and the Back Electromotive Force (BEMF) detection system. This high-impedance leg is configured to sense the BEMF voltage without being directly affected by the switching transients and noise from the PWM signal. The intermediary high-impedance configuration allows accurate rotor position determination by isolating the measurement process from the harmful rising and falling edges of the modulated drive signal.

The patent applies segmentation by separating the three-phase motor control into distinct functional segments: one leg is dedicated to PWM driving while another leg is configured as a high-impedance sensing leg for BEMF measurement. This segmentation isolates the noisy switching operation from the sensitive measurement operation, allowing each segment to perform its function optimally without interfering with the other. The segmented approach enables simultaneous PWM control and accurate rotor position determination.

The patent applies the 'blessing in disguise' principle by converting the harmful noise and errors generated by PWM switching into useful information. Instead of attempting to eliminate the noise through filtering and damping, the system uses the high-impedance sensing leg to detect the Back Electromotive Force (BEMF) voltage that exists on the motor winding during the PWM switching cycles. The BEMF signal, which would normally be obscured by switching noise, is actually enhanced by the high-impedance configuration and can be used to accurately determine rotor position and improve overall system performance.

The patent applies inversion by reversing the conventional approach to noise reduction. Instead of using low-impedance filtering and damping circuits that attenuate both noise and useful signals, the system uses a high-impedance configuration that naturally rejects the switching noise while preserving the BEMF signal. This inverted approach—using high impedance rather than low impedance for noise reduction—allows the system to improve measurement accuracy without sacrificing system-level performance through aggressive filtering.