Steering Motor Power Path Control for Fault-Tolerant Assist
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Solution Overview
Problem
The increasing demand for reliability and safety in vehicle steering systems, particularly in autonomous vehicles, is not adequately met by existing electromotive power steering systems due to concerns about the reliability and safety of the power source device of the steering motor.
Innovation Solution
A steering assist device is introduced, comprising multiple power path controllers and a controller unit that monitor and control the operation of the inverter and power path controllers to determine the state of the power paths based on phase voltages, ensuring the safe operation of the steering motor by managing assist steering forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If electromotive power steering systems are used to reduce steering force, then steering stability is improved, but reliability and safety of the power source device deteriorate
Solution Approach 1:
The power source device is segmented into three independent power paths (Ath, Bth, Cth), each with its own power path controller. This segmentation allows individual monitoring and control of each power path, enabling the system to maintain reliability while providing steering assistance through multiple independent channels.
Solution Approach 2:
Power path controllers are introduced as intermediary devices between the inverter legs and the steering motor phases. These controllers monitor phase voltages and control the power flow, acting as a protective layer that enhances the reliability of the power source device while maintaining the electromotive steering function.
2Reliability
If multiple power path controllers are added to monitor and control power paths, then reliability and safety are improved, but device complexity increases
Solution Approach 1:
The power path controllers perform multiple functions: they monitor phase voltages, control power flow to the steering motor, and provide safety protection. By making these controllers multi-functional, the patent reduces the need for separate dedicated components, thereby limiting the increase in device complexity while achieving improved reliability.
Solution Approach 2:
The patent combines the monitoring and control functions into the existing inverter structure, merging the power path controllers with the inverter legs. This integration approach reduces overall system complexity by eliminating separate monitoring and control units that would otherwise be needed.
Data Source
AI summary
A steering assist device may comprise an Ath power path controller positioned on an Ath power path connecting an Ath leg of an inverter with an Ath phase of a steering motor, a Bth power path controller positioned on a Bth power path connecting a Bth leg of the inverter with a Bth phase of the steering motor, a Cth power path controller positioned on a Cth power path connecting a Cth leg of the inverter with a Cth phase of the steering motor, and a controller unit determining a state of at least one of the Ath power path controller to the Cth power path controller based on at least one of an Ath phase voltage to a Cth phase voltage respectively formed at the Ath leg to the Cth leg of the inverter and controlling the steering motor according to a result of the determination.