Dual Inverter Control for Electric Steering Voltage Mismatch
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Solution Overview
Problem
Existing vehicle steering systems face issues with power source degradation and overheating due to voltage differences between redundant batteries, even when both power sources are within normal ranges, leading to further degradation and heat radiation problems.
Innovation Solution
A control apparatus for a rotary electric machine with two winding groups, each connected to an inverter and a control unit, which detects voltage differences and limits current command values to prevent degradation and heat issues by switching power sources when voltage differences exceed a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two power sources are continuously used to ensure system reliability, then system reliability is improved, but power source degradation accelerates and overheating occurs
Solution Approach 1:
The control apparatus dynamically changes the operating parameters (current command values) of the power sources based on detected voltage differences. When a voltage difference exceeds the threshold, the system adjusts the current distribution to reduce stress on the lower-voltage power source, thereby extending its lifespan while maintaining system operation
Solution Approach 2:
The system transitions from a static continuous-use configuration to a dynamic configuration where the operational status of each power source changes based on real-time voltage monitoring. The control unit dynamically switches between using both power sources and using only one power source based on the detected voltage difference, optimizing both reliability and lifespan
2Productivity
If two power sources are continuously used to maintain operation, then operational continuity is improved, but heat radiation increases at contact resistance points
Solution Approach 1:
The control apparatus changes the electrical parameters (current command values) based on voltage differences between power sources. When voltage difference exceeds the threshold, the system reduces current through the lower-voltage power source, thereby reducing I²R heating at contact resistance points and preventing overheating while maintaining operational continuity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses power system degradation and reduces heat radiation at points with large voltage drops, ensuring stable operation and extending battery life by dynamically adjusting current command values based on voltage differences between the two power sources.
Implementation Method 1
a first voltage detector configured to detect a first inverter input voltage entering the first inverter; a second voltage detector configured to detect a second inverter input voltage entering the second inverter
Implementation Method 2
either voltage sometimes decreases. In this case, when two power sources are continuously used, the power source having lower voltage may be further degraded, or overheating may occur at a portion where the contact resistance is increased
Implementation Method 3
overheating may occur at a portion where the contact resistance is increased
Data Source
AI summary
An apparatus for controlling a rotary electric machine includes: first and second inverters corresponding to first and second winding groups; first and second voltage detectors; and first and second control units. Each of the first and second inverters includes plurality of switching elements. The first and second voltage detectors each detects input voltage of corresponding inverter. The first control unit limits a first current command value of the first winding group, when both of the first and second inverter input voltages are in normal, and a first differential value is larger than a determination threshold, and the second control unit limits a second current command value of the second winding group, when both of the first and second inverter input voltages are normal, and a second differential value is larger than the determination threshold.