Dual-Inverter Open-End Winding Control for Zero-Phase Voltage Balance
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Solution Overview
Problem
In motor driving systems using the open end winding method, common mode current is generated due to unequal zero phase component voltages between inverters, leading to inefficiencies like copper and iron losses, and potential damage from fires.
Innovation Solution
A motor driving apparatus with a controller that synchronizes the zero phase component voltages between two inverters by distributing voltage commands equally and generating offset voltage commands based on phase voltage commands, ensuring identical common mode voltages to eliminate circulating currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the open end winding method is used to increase voltage utilization rate and output, then motor power is improved, but common mode current is generated causing copper loss and iron loss
Solution Approach 1:
The patent changes the control parameters by introducing offset voltage commands that adjust the zero-phase component voltages of the two inverters. By modifying the voltage commands applied to each inverter based on their respective phase voltage characteristics, the system eliminates common mode current while maintaining the high output power benefits of the open end winding method
Solution Approach 2:
The controller continuously monitors the phase voltage commands from both inverters and dynamically adjusts the offset voltage commands based on the detected voltage differences. This feedback mechanism ensures that the zero-phase component voltages are balanced, preventing common mode current generation while maintaining optimal motor performance
2Loss of energy
If the open end winding method is used to increase voltage utilization rate, then motor efficiency is improved, but circulating current is generated that may cause fire damage
Solution Approach 1:
The patent applies preliminary anti-action by proactively balancing the zero-phase component voltages before common mode current can cause harmful effects. The controller pre-adjusts the offset voltage commands to prevent voltage imbalances that would lead to circulating currents and potential fire damage, rather than reacting after the problem occurs
3Device complexity
If conventional Y-connection is used to simplify motor structure, then device complexity is reduced, but voltage utilization rate is limited
Solution Approach 1:
The patent segments the motor control into two independent inverter systems, each controlling one end of the open windings. This segmentation allows each inverter to be optimized independently with specific offset voltage commands, achieving high voltage utilization without requiring complex winding connections while maintaining system simplicity
Data Source
AI summary
A motor driving apparatus which drives a motor having a plurality of windings corresponding to a plurality of phases includes: a first inverter having a plurality of first switching elements and connected to a first end of each winding; a second inverter having a plurality of second switching elements and connected to a second end of each winding; and a controller configured to control pulse width modulation, by distributing a preset voltage command of the motor into a voltage command of the first inverter and a voltage command of the second inverter at the same rate and by generating duties of the first switching elements, wherein the controller determines the duties of the second switching elements and determines the duties of the first switching elements on and the duties of the first switching elements.