Rotary Electric Machine Control Circuit Calculation Load Reduction
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Solution Overview
Problem
Conventional rotary electric machine control devices face a heavy calculation load due to the need for complex control operations, including automatic steering and assist control, which can restrict the use of microcomputers and impact in-vehicle security and functional safety.
Innovation Solution
The rotary electric machine control device incorporates a control circuit that switches between angle control and torque control modes, optimizing calculation cycles and frequencies based on the control mode to reduce the overall calculation load, thereby improving operational efficiency and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If complex control operations (automatic steering control and assist control) are executed simultaneously, then steering functionality is improved, but calculation load increases
Solution Approach 1:
The control device dynamically switches between angle control mode and torque control mode based on operational conditions. In angle control mode, the motor is controlled to follow a target angle trajectory; in torque control mode, the motor provides assist torque based on detected steering torque. This dynamic switching reduces calculation load while maintaining necessary steering functionality.
Solution Approach 2:
The control device changes control parameters by switching between different control modes (angle control and torque control). Each mode uses different control parameters and calculation methods, allowing the system to reduce computational complexity while maintaining steering performance by selecting the appropriate parameter set for current operating conditions.
2Reliability
If operation checking is performed in addition to assist control, then steering safety is improved, but calculation load increases
Solution Approach 1:
The control device extracts and separates the operation checking function from the main control loop. By implementing operation checking as a distinct monitoring function that operates independently from the primary angle or torque control calculations, the system ensures steering safety through continuous monitoring without significantly increasing the calculation burden of the main control algorithm.
3Speed
If calculation cycle is optimized for responsiveness, then operational responsiveness is improved, but calculation precision may be reduced
Solution Approach 1:
The control device implements periodic control cycles with optimized timing. By structuring the control algorithm to perform essential calculations at specific intervals and using predictive methods between cycles, the system achieves high operational responsiveness while maintaining sufficient calculation precision through strategic timing of computational operations.
Data Source
AI summary
An ECU including a control circuit is provided to control driving of a motor, which outputs at least a part of torque required for steering a vehicle. The control circuit is configured to switch control modes including an ADS mode for controlling driving of the motor based on an angle command value and an EPS mode for controlling the driving of the motor based on a basic assist command value which is a torque command value. The control circuit is configured to change the calculation cycle period of at least a part of the calculations related to the driving control of the motor according to the selected control mode. Accordingly, an appropriate calculation cycle period can be set for each calculation related to the driving control of the motor according to the control mode, and the calculation load can be reduced.