Open-End Winding Inverter Control for Common-Mode Voltage Removal
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Solution Overview
Problem
The open-end winding motor driving technique faces inefficiencies due to common mode voltage and current issues, which cause copper and iron losses and potentially lead to motor burnout, while trying to maximize power conversion efficiency and torque for eco-friendly vehicles.
Innovation Solution
A motor driving apparatus is designed to control the duty of first switching elements such that the one-period average of common mode voltage matches the voltage command, using a controller that adjusts the duty of first switching elements through pulse width modulation to remove common mode voltage and current, employing methods like remote state pulse width modulation and symmetric pulse width modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the open-end winding method is used to increase voltage utilization rate and maximum torque, then the power conversion efficiency is improved, but common mode voltage and current are generated causing copper loss and iron loss
Solution Approach 1:
The controller measures the actual common mode voltage and feeds it back to adjust the switching duty cycles of the first inverter, ensuring the one-period average common mode voltage matches the voltage command of common mode, thereby eliminating common mode current and reducing copper loss and iron loss
Solution Approach 2:
The invention changes the switching parameters (duty cycles) of the first inverter's switching elements based on the common mode voltage condition, optimizing the pulse width modulation to eliminate harmful common mode components while maintaining the beneficial high voltage utilization of the open-end winding method
2Use of energy by moving object
If the open-end winding method is used to improve voltage utilization rate, then the fuel efficiency is improved, but common mode current flows through the winding causing motor efficiency to deteriorate
Solution Approach 1:
The controller continuously monitors and adjusts the switching duty cycles based on the common mode voltage feedback, ensuring that the one-period average common mode voltage matches the voltage command, thereby preventing common mode current flow and maintaining high motor efficiency
Solution Approach 2:
The invention extracts and eliminates the harmful common mode voltage component from the inverter output by adjusting the first inverter's switching duty cycles, separating the useful differential mode voltage from the harmful common mode voltage to improve motor efficiency
3Power
If the open-end winding method is used to increase phase voltage, then the output power is increased, but common mode voltage generates common mode current causing potential motor burnout
Solution Approach 1:
The controller uses feedback control to measure the actual common mode voltage and adjust the first inverter's switching duty cycles accordingly, ensuring the one-period average common mode voltage matches the voltage command, thereby preventing common mode current generation and protecting against motor burnout
Solution Approach 2:
The invention applies preliminary control by pre-adjusting the switching duty cycles of the first inverter based on the common mode voltage condition before harmful common mode current can flow, eliminating the harmful effect at its source while maintaining high output power
Data Source
AI summary
A motor driving apparatus driving a motor that has a plurality of windings respectively corresponding to a plurality of phases includes 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 determining a voltage command of the first inverter based on a voltage command of the motor and the active vector corresponding to a duty of the second switching elements and controlling the first switching elements through pulse width modulation based on the voltage command of the first inverter.