Redundant EPS Motor Control with Separate Pre-Drivers
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Solution Overview
Problem
The motor control device in existing electric power steering systems is vulnerable to instability due to potential abnormalities in the shared pre-driver of the main and auxiliary control units.
Innovation Solution
A motor control device with a double redundant control system, featuring separate pre-drivers and switch control units for each control unit, ensuring stable operation even if one pre-driver fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a shared pre-driver is used in the main and auxiliary control units, then device complexity is reduced, but reliability deteriorates because a single point of failure can cause both control units to malfunction simultaneously
Solution Approach 1:
The patent divides the pre-driver functionality into separate independent units for the main control unit and auxiliary control unit. Each control unit has its own dedicated pre-driver, eliminating the shared resource that caused the single point of failure. This segmentation ensures that a failure in one pre-driver does not affect the other control unit, thereby resolving the reliability issue while maintaining reasonable device complexity through modular design.
2Reliability
If a double redundant control system is implemented, then reliability is improved by providing backup control capability, but device complexity increases due to additional components and interconnections
Solution Approach 1:
The patent implements a simplified redundancy strategy where the auxiliary control unit is designed as a functional copy of the main control unit, but with deliberately omitted components (such as certain sensors or communication interfaces) to reduce overall complexity. This selective copying provides adequate backup capability for safety-critical functions while avoiding the full complexity duplication that would result from completely redundant systems.
3Reliability
If separate pre-drivers are provided for main and auxiliary control units, then reliability is improved by eliminating single points of failure, but device complexity increases due to additional components
Solution Approach 1:
The patent applies local quality by providing separate pre-drivers specifically at the critical interface between the control units and the motor drive circuitry, where failures would have the most significant impact on system reliability. Other non-critical components may still be shared between main and auxiliary control units, thereby achieving improved fault tolerance at critical points without unnecessarily increasing overall device complexity throughout the entire system.
Data Source
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AI summary
A motor control device according to the present disclosure includes: a motor drive circuit that outputs a drive current to a motor; a drive current detector; a main control unit, and an auxiliary control unit, wherein the main control unit has a first control signal generator that generates a first control signal based on a detected current signal; a first drive signal generator that generates a drive signal based on the first control signal, and a first switcher that switches to an output state of the motor drive circuit of the drive signal, and the auxiliary control unit has a second control signal generator that generates a second control signal; a second drive signal generator that generates the drive signal based on the second control signal, and a second switcher that switches to an output state of the motor drive circuit of the drive signal.