Electronic Control Apparatus Fault Tolerance via Dynamic Power Reduction
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Solution Overview
Problem
Existing electronic control apparatuses for automobiles face challenges in maintaining operation during faulty conditions without increasing circuit scale, dimensions, weight, and cost, particularly in electric power steering systems where redundant subsystems are required for safety.
Innovation Solution
The electronic control apparatus employs multiple voltage regulators, a master and slave control unit configuration, and power consumption reduction methods, such as clock frequency reduction and simpler circuit designs, to ensure continued operation while minimizing redundancy-related increases in size, weight, and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant subsystems are incorporated to enable continued operation during faults, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The control unit dynamically switches between normal operation mode and fault operation mode based on system conditions. When a fault is detected in a voltage regulator, the system transitions to using only the remaining functional regulator and adjusts power consumption accordingly, enabling continued operation without requiring permanent redundant hardware for all scenarios
Solution Approach 2:
The system changes operational parameters (power consumption level, clock frequency) based on the number of functional voltage regulators. By adjusting these parameters dynamically, the system maintains reliability during faults while avoiding the need for permanently oversized circuits that would be required if full redundancy were always maintained
2Use of energy by moving object
If the operating clock frequency is reduced to lower power consumption, then energy efficiency is improved, but processing speed decreases
Solution Approach 1:
The clock frequency is dynamically adjusted based on system conditions. During normal operation with all voltage regulators functional, the system operates at full clock frequency for maximum performance. When faults occur and power consumption must be reduced, the system transitions to a lower clock frequency mode, accepting reduced processing speed in exchange for energy savings during fault conditions
3Reliability
If a master-slave control unit configuration is used, then reliability is improved through redundancy, but device complexity increases
Solution Approach 1:
The control unit is segmented into master and slave functional components that can operate independently. The slave control unit is designed with simplified circuitry specifically for fault mode operation, while the master handles normal operation. This segmentation allows the system to achieve fault tolerance without duplicating the entire complex control unit
Solution Approach 2:
Different parts of the control system have different levels of complexity appropriate to their function. The slave control unit has simpler circuitry optimized for basic fault mode operation, while the master control unit has full complexity for normal operation. This local differentiation of quality reduces overall system complexity while maintaining reliability
Data Source
AI summary
An electronic control apparatus includes a control unit, a plurality of power supply units for supplying the control unit with power, and a power supply fault detector unit for detecting a fault in the plurality of power supply units. The control unit operates in a normal mode on electric power supplied from the plurality of power supply units when none of the plurality of power supply units is faulty.