EPB Control Unit Redundancy via Dual MCU Segmentation
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Solution Overview
Problem
In electronic parking brake systems, a fault in the main microcontroller (MCU) can lead to uncontrolled operation of actuators, compromising the reliability of the system due to the lack of redundancy and potential malfunctions.
Innovation Solution
A control unit is introduced that includes multiple MCUs and driver circuits, with a cut-off circuit in each actuator to prevent malfunctions, allowing the secondary MCU to drive the second motor when a fault occurs in the first MCU, ensuring continued operation and redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single main MCU controls all actuators in the electronic parking brake system, then the device complexity is reduced, but the reliability deteriorates because a fault in the main MCU causes uncontrolled operation of actuators
Solution Approach 1:
The control unit is segmented into multiple independent MCUs (first MCU and second MCU), each capable of controlling the actuators. This segmentation allows the system to maintain functionality even if one MCU fails, as the other MCU can take over control, thereby resolving the reliability issue while keeping the overall structure manageable
Solution Approach 2:
The system changes the operational parameter from a single-controller architecture to a multi-controller architecture with failover capability. By introducing a backup MCU and implementing switchable control paths through driver circuits, the system transforms from a single point of failure to a redundant configuration, improving reliability without excessive complexity
2Reliability
If multiple MCUs are used to improve reliability, then the system reliability improves, but the device complexity increases due to additional control units and circuits
Solution Approach 1:
Multiple driver circuits are merged into a single control unit housing, and multiple MCUs share common resources including power supply circuits, communication interfaces, and the actuator control bus. This merging approach allows redundancy without proportionally increasing overall system complexity, as shared resources reduce the total component count compared to completely separate control units
Solution Approach 2:
Both MCUs are designed with identical or similar functional capabilities, allowing either MCU to perform the complete set of control functions. This multi-functionality ensures that the backup MCU can fully replace the primary MCU in case of failure, providing reliability while using standardized components that reduce design complexity
3Reliability
If a cut-off circuit is added to prevent MCU malfunction propagation, then the reliability improves, but the device complexity increases due to additional circuit components
Solution Approach 1:
Cut-off circuits are preliminarily configured in the power supply paths and control signal lines between MCUs and driver circuits. These circuits include isolation transistors or diodes that are pre-positioned to automatically disconnect faulty sections. By having these protective elements in place before faults occur, the system can isolate malfunctions without requiring complex real-time decision logic, thus improving reliability with minimal added complexity
Data Source
AI summary
The present disclosure relates to a control unit of an electronic parking brake system, including: a plurality of driver circuits which are respectively connected to a first motor and a second motor for providing a driving force to an electronic parking brake to control the first motor and the second motor; a first micro control unit (MCU) which has a plurality of core processors and is connected to a first driver circuit and a second driver circuit receiving a first power according to a reception of an electric parking brake (EPB) switch signal; and a second MCU which has at least one core processor and is connected to a third driver circuit receiving a second power. The control unit can be applied to other exemplary embodiments.