Motor Control Unit Single Reverse-Connection Protection FET
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Solution Overview
Problem
The existing electric power steering apparatus with dual-system windings faces increased costs due to the need for two reverse-connection protection-FETs, which are required to prevent overcurrent and protect the control unit when one FET driving circuit fails.
Innovation Solution
A motor control unit with a single reverse-connection protection-FET connected between dual-system inverters and a power supply, where the protection-FET is turned ON/OFF by a logical sum of gate driving signals from both gate driving sections, allowing the system to maintain operation even if one FET driving system fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two reverse-connection protection-FETs are used in dual-system configuration, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the protection functions of two separate FETs into a single shared protection-FET that is commonly connected to both first and second inverters. This single FET replaces the traditional dual-FET configuration, reducing device count while maintaining protection capability through logical sum control of gate driving signals from both driving sections.
Solution Approach 2:
The protection-FET serves multiple functions: it protects both the first inverter and second inverter from reverse connection damage, and can operate in redundancy mode where either driving section can control it independently. This multi-functional design allows one FET to perform the role previously requiring two separate FETs.
2Reliability
If two reverse-connection protection-FETs are used, then protection capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines the protection function against reverse connection into a single shared FET that protects both inverters, eliminating the need to manufacture and assemble two separate protection-FETs. This reduces component count, assembly steps, and overall manufacturing cost while maintaining the same protection capability.
Solution Approach 2:
The single protection-FET is designed to universally protect both inverters through common connection and logical sum control, making it a multi-functional component that replaces two specialized components, thereby reducing manufacturing complexity and cost.
3Device complexity
If a single protection-FET is used, then device complexity is reduced, but reliability may deteriorate
Solution Approach 1:
The patent implements dynamic control of the single protection-FET through logical sum of gate driving signals from both driving sections. This dynamic control mechanism allows the FET to respond to commands from either driving section independently, maintaining system reliability through adaptive operation modes including redundancy control when one driving section fails.
Solution Approach 2:
The patent incorporates beforehand cushioning by designing the control unit to detect driving section abnormalities and automatically switch to redundancy control mode. This prior preparation ensures that when one driving section fails, the other can still control the protection-FET, preventing system failure and maintaining reliability.
Data Source
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AI summary
[Problem] An object of the present invention is to provide a motor control unit that driving-controls a motor having the dual-system windings, even in a case that one driving control system is an abnormality (including a failure), turns-ON of one common reverse-connection protection-FET by a driving signal of the other normal driving control system, and achieves a miniaturization and a reduction in costs, an electric power steering apparatus that is equipped with the motor control unit, and a vehicle. [Means for solving the problem] The present invention is the motor control unit, comprising: an MCU to control the motor having dual-system motor windings, dual-system inverters to drive the respective dual-system motor windings via dual-system driving sections, and one reverse-connection protection-FET that is connected between the dual-system inverters and a power supply, wherein the reverse-connection protection-FET is turned-ON or turned-OFF by a logical sum of gate driving signals from the dual-system gate driving sections.