Electric Power Steering Apparatus Redundant Control Circuit Topology
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Solution Overview
Problem
Conventional electric power steering apparatuses with redundant control units increase cost and complexity, particularly due to the need for additional connectors and noise mitigation from high-current inverter circuits.
Innovation Solution
An electric power steering apparatus with two sets of armature windings and control units, where a single power-source connector branches into two lines, allowing each controller to independently control an armature winding, and incorporating a power-source relay, filter circuit, and inverter circuit to manage power and noise, with abnormality detection for seamless system continuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two sets of control units are provided to secure redundancy, then system reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines two control units into a single integrated control unit that contains two independent control circuits. This merging approach maintains the redundancy function (improving reliability) while reducing the number of physical control units, connectors, and harnesses (reducing device complexity and cost). The single control unit shares common components like the microcomputer and memory, while maintaining separate control circuits for dual-armature-winding failure isolation.
2Reliability
If two sets of control units are provided to secure redundancy, then system reliability is improved, but cost increases
Solution Approach 1:
The patent merges two control units into one, reducing the total number of components that need to be manufactured, assembled, and tested. This single control unit with integrated dual control circuits reduces material costs, assembly costs, and testing costs while maintaining the redundancy function through isolated control circuits that can independently manage each armature winding.
3Device complexity
If a single power-source connector is used with branched lines, then device complexity is reduced, but noise emission from inverter circuits increases
Solution Approach 1:
The patent segments the power supply path by providing separate power-source connectors for each control circuit's inverter circuit. Although the control units are merged into one, the power delivery paths are separated to prevent noise interference. This segmentation of the power distribution system allows each inverter circuit to have its own dedicated power connection, reducing electromagnetic interference and noise emission while maintaining the simplified single-control-unit structure.
Data Source
AI summary
Two sets of independent armature windings and two sets of control units are provided; a single power-source connector branches into at least four lines in the vicinity of a power-source terminal; a power source relay, a filter, and an inverter circuit are connected, in that order, with a line where a large current flows; a control circuit unit is connected with a line where a small current flows and a detection circuit for detecting an abnormality in the control circuit unit is provided in that line.