Motor PWM Carrier Phase Shift for Pulsation and Torque Control
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Solution Overview
Problem
Shifting the phase of the carrier wave in motor control devices reduces motor pulsation but leads to a decrease in torque, which is undesirable.
Innovation Solution
A motor control device and method that includes an inverter circuit driven by a control unit generating current command values based on a torque command, with a phase shift amount of the carrier wave being set to estimate and correct the current command values for fluctuating torque, thereby reducing motor pulsation while maintaining torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the phase of the carrier wave is shifted to reduce motor pulsation, then motor pulsation is reduced, but motor torque decreases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the phase shift amount of the carrier wave based on operating conditions (torque command, rotational speed). The control unit selects optimal phase shift amounts from multiple predetermined values, changing the parameter (phase shift) to reduce pulsation while maintaining torque through conditional selection rather than fixed adjustment
Solution Approach 2:
The patent implements dynamics by making the phase shift amount variable rather than fixed. The control unit dynamically selects different phase shift amounts based on real-time operating conditions (torque command and rotational speed ranges), allowing the system to adapt to changing conditions and optimize both pulsation reduction and torque maintenance across different operating points
Data Source
AI summary
A motor control device includes: an inverter circuit that drives a motor; and a control unit that generates a current command value on the basis of a torque command to the motor, and outputs a PWM pulse to the inverter circuit on the basis of the current command value to control the inverter circuit, and the control unit sets a phase shift amount of a carrier wave of the PWM pulse, estimates a fluctuating torque according to the phase shift amount, and corrects the current command value on the basis of the fluctuating torque.