Rotary Electric Device Control for EPS Torque Consistency
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Solution Overview
Problem
In electric power steering systems, inconsistencies in assist control calculations between independent microcomputer systems can lead to inefficiencies and increased complexity in arbitration, affecting torque output and heat management.
Innovation Solution
A rotary electric device control device with multiple control units, including a master and slave system, coordinates driving by transmitting command values and performing current feedback control, reducing inconsistencies and complexity through coordinated energization and phase difference optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two microcomputers independently calculate assist control amounts, then system redundancy is improved, but control complexity and inconsistency increase
Solution Approach 1:
The control system is segmented into a master control unit and slave control unit. The master control unit performs comprehensive calculations including basic assist control amount and correction amounts, while the slave control unit executes predetermined calculations based on master's commands. This segmentation maintains redundancy benefits while reducing overall control complexity.
Solution Approach 2:
A communication unit acts as an intermediary between the master and slave control units. The master control unit transmits command values to the slave control unit through this intermediary, coordinating their operations and ensuring consistent assist control amounts without requiring complex inter-microcomputer arbitration.
2Reliability
If multiple control units operate independently, then system reliability is improved, but heat generation increases
Solution Approach 1:
The slave control unit performs only predetermined calculations based on command values from the master control unit, rather than performing full independent calculations. This partial action approach maintains system redundancy while significantly reducing the computational load and heat generation in the slave unit.
3Reliability
If independent microcomputer systems are used, then system robustness is improved, but assist control consistency deteriorates
Solution Approach 1:
The master control unit provides feedback command values to the slave control unit through the communication unit. This feedback mechanism ensures that both control units operate with consistent information, maintaining assist control consistency while preserving the robustness benefits of having multiple control units.
Data Source
AI summary
A rotary electric device control device controls driving of a rotary electric device including a plurality of winding sets. The rotary electric device control device includes: a plurality of drive circuits; and a plurality of control units. The control units include signal output units for outputting control signals to the drive circuits corresponding to the control units, respectively, and communicate with each other. The control units include: one master control unit; and at least one slave control unit. An electric power steering device includes: a rotary electric device control device; the rotary electric device that outputs an assist torque for assisting a steering operation of a steering wheel by a driver; and a power transmission unit that transmits a driving force of the rotary electric device to a drive target.