Dual MCU Motor Control Backup Clock for Error Continuity
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Solution Overview
Problem
Existing motor control systems face challenges in continuing motor control when errors occur in the main MCU, particularly in extreme conditions like those encountered in EVs and hybrid vehicles, due to the lack of redundancy in calculation means.
Innovation Solution
A motor control system comprising a first MCU with an error detection unit, a resolver digital converter, and a PWM generation unit, and a second MCU with a backup clock supply unit, encoder counter, and a PWM generation unit, where the second MCU provides a backup clock to the first MCU to maintain operation even when errors are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single main MCU is used for motor control calculation, then device complexity is reduced, but reliability deteriorates when errors occur in the main MCU
Solution Approach 1:
The motor control system is segmented into two independent MCUs: a main MCU for primary control calculations and a sub MCU for backup control calculations. This segmentation allows the system to maintain motor control functionality even when one MCU fails, resolving the contradiction between reduced complexity and improved reliability.
Solution Approach 2:
The system changes the operational state parameter of the sub MCU from a dormant backup to an actively running calculation unit. By keeping the sub MCU operational with its own clock and calculation capabilities, the system achieves failover capability without requiring complete system redesign, thus improving reliability while controlling complexity.
2Reliability
If sub calculation means is used for motor control when IG switch is OFF, then productivity is improved during shutdown, but reliability deteriorates when error occurs in main MCU
Solution Approach 1:
The sub MCU is prepared in advance as a standby calculation unit with all necessary computational capabilities. Its clock is stopped during normal operation to save power, but it can be quickly activated when the main MCU fails. This preliminary preparation enables reliable failover while minimizing the impact on device complexity.
Solution Approach 2:
The system dynamically changes the operational state of the sub MCU based on the health status of the main MCU. When the main MCU is functioning normally, the sub MCU remains in a low-power standby state. When an error is detected, the sub MCU transitions to an active calculation state, providing dynamic adaptability that improves reliability without permanently increasing device complexity.
Data Source
AI summary
A motor control system includes a first MCU and a second MCU. The first MCU includes an error detection unit, a resolver digital converter, and a first PWM generation unit. The resolver digital converter includes an encoder unit, which generates encoder pulses based on angle information and outputs the encoder pulses to the second MCU. The error detection unit outputs an error signal to the second MCU, when an error is detected in the first MCU. The first MCU controls the resolver digital converter to operate using a backup clock supplied from the second MCU.