Open-End Winding Motor Control for Common-Mode Current Suppression
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Solution Overview
Problem
The open end winding (OEW) motor driving method, which connects inverters to both ends of a motor winding, faces inefficiencies due to common mode currents causing copper and iron losses, potentially damaging the motor system.
Innovation Solution
A motor driving apparatus with a controller that applies 3rd harmonic feedforward compensation to reduce zero-phase component current errors, using a current controller to compare and produce voltage commands that minimize errors between current commands and actual currents, thereby suppressing common mode currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If open end winding scheme is used to increase phase voltage and improve voltage utilization rate, then motor power output is improved, but common mode current is generated causing copper loss and iron loss
Solution Approach 1:
The patent applies 3rd harmonic feedforward compensation by injecting a 3rd harmonic voltage component into the voltage command. This parameter change in the voltage waveform eliminates the common mode current while maintaining the high phase voltage benefit of the open end winding scheme, thereby reducing copper loss and iron loss without sacrificing motor power output.
2Use of energy by moving object
If open end winding scheme is used to increase phase voltage, then voltage utilization rate is improved, but common mode current may damage the motor system
Solution Approach 1:
The patent implements preliminary anti-action by proactively injecting a 3rd harmonic voltage component before common mode current can cause damage. This preemptive measure eliminates the zero-phase voltage that generates common mode current, protecting the motor system from potential damage while maintaining high voltage utilization rate.
3Loss of energy
If 3rd harmonic feedforward compensation is applied to reduce common mode current, then motor efficiency is improved, but control complexity increases
Solution Approach 1:
The patent calculates the 3rd harmonic voltage component in advance based on motor operating parameters (speed, torque, position) and adds it to the voltage command before execution. This preliminary calculation approach simplifies the control implementation compared to complex feedback-based common mode current suppression methods, improving motor efficiency without excessive control complexity.
Data Source
AI summary
A motor driving apparatus that drives a motor including a plurality of windings respectively corresponding to a plurality of phases, may include a first inverter including a plurality of first switching elements, and connected to a first end of each of the windings; a second inverter including a plurality of second switching elements, and connected to a second end of each of the windings; and a controller including a current controller to produce, based on a predetermined current command of the motor, a voltage command for determining a switching duty of the first switching elements and the second switching elements, wherein the current controller is configured to produce a zero-phase component voltage command among the voltage commands by applying 3rd harmonic feedforward compensation.