Redundant Electric Power Steering Architecture
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Solution Overview
Problem
The existing electric power steering apparatus lacks redundancy, which compromises reliability and safety, especially in scenarios where abnormalities occur in internal systems, such as ECU or sensor failures, potentially impacting vehicle stability and safety, especially with the integration of advanced technologies like automatic driving.
Innovation Solution
The electric power steering apparatus is designed with redundancy for each component, featuring two independent dual die ICs in torque and steering angle sensors, a dual-wound BLAC motor with separate winding motors and inverters, and two ECUs with separate power supplies, allowing for seamless switching between ECUs and sensors to maintain normal steering control even if one ECU or sensor fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundancy is configured for each component in the electric power steering apparatus, then reliability and safety are improved, but device complexity increases
Solution Approach 1:
The electric power steering apparatus is divided into multiple independent functional modules: first ECU with first sensor suite, second ECU with second sensor suite, dual-wound motor with separate winding motors. Each module can operate independently, allowing the system to maintain functionality even when one module fails, thus resolving the contradiction between reliability and complexity through modular segmentation.
Solution Approach 2:
Different ECUs and sensor suites are configured with specialized local functions. The first ECU handles specific sensor inputs (torque, steering angle, motor position) while the second ECU handles complementary inputs. This local specialization allows each subsystem to be optimized for its specific function while contributing to overall system redundancy and reliability.
2Reliability
If separate power supply devices are used for first ECU and second ECU, then system reliability is improved, but device complexity and cost increase
Solution Approach 1:
The power supply system is segmented into separate power sources for the first ECU and second ECU. This segmentation ensures that a power failure or electrical fault in one ECU does not affect the operation of the other ECU, maintaining steering functionality through electrical isolation and thereby resolving the reliability-complexity contradiction.
3Reliability
If dual-wound motor with separate winding motors is used, then steering control reliability is improved, but device complexity and space requirements increase
Solution Approach 1:
Two separate winding motors are merged into a single dual-wound motor assembly that shares common structural elements such as the stator core, rotor, and housing. This merging approach provides the reliability benefits of having separate motor windings controlled by different ECUs while minimizing the volume increase compared to two completely separate motors.
Data Source
AI summary
The present disclosure aims to provide an electric power steering apparatus which is improved in reliability compared to an existing electric power steering apparatus by configuring redundancy for an electronic system therein. An embodiment provides a electric power steering apparatus including: a four-channel torque sensor including two independent dual die ICs; a four-channel steering angle sensor including two independent dual die ICs; a four-channel motor position sensor including two independent dual die ICs; a dual-wound Brushless AC (BLAC) motor including a first winding motor and a second winding motor therein; a first Electronic Control Unit (ECU); a second ECU; and a selector configured to select an ECU that controls steering among the first ECU and the second ECU. The first ECU and the second ECU are supplied with power from separate power supply devices which are separated from each other, the first winding motor of the dual-wound BLAC motor is connected to an inverter of the first ECU, and the second winding motor of the dual-wound BLAC is connected to an inverter of the second ECU.