Motor Controller Dual Shutoff Paths for Functional Safety
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Solution Overview
Problem
The high difficulty in designing a motor controller for pure electric or hybrid vehicles due to stringent functional safety requirements, particularly in determining the appropriate safety state based on motor speed, leading to high safety level demands on each device in the shutoff path.
Innovation Solution
A motor controller design incorporating a microprocessor, monitoring chip, logic operation circuits, and an overvoltage detection circuit to generate control signals for entering safety states, with two independent shutoff paths that reduce the safety level requirement on each device, allowing for safer operation by determining motor speed and DC bus voltage states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single shutoff path with high safety level requirement is used to determine safety state based on motor speed, then the functional safety is ensured, but the device complexity and design difficulty increase significantly
Solution Approach 1:
The patent divides the single shutoff path into two independent shutoff paths: a first shutoff path for determining safety states based on motor speed, and a second shutoff path for determining safety states based on DC bus voltage. Each path has its own logic operation circuit and can independently control the main circuit to enter safety states. This segmentation reduces the safety level requirement on each individual path while maintaining overall functional safety through redundancy.
2Reliability
If the safety level requirement on each device in the shutoff path is increased to ensure functional safety, then the safety goal is achieved, but the ease of manufacture and design difficulty worsen
Solution Approach 1:
The patent segments the safety function into two independent shutoff paths with separate logic operation circuits. The first logic operation circuit handles motor speed-based safety determination, while the second logic operation circuit handles DC bus voltage-based safety determination. This segmentation allows each device in the paths to have lower individual safety level requirements, making the system easier to manufacture and design while maintaining overall high functional safety through the redundant dual-path architecture.
Data Source
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AI summary
A motor controller according to the present disclosure obtains the rotational speed determination signal of the motor through the microprocessor and the rotational speed collector, and then outputs the first control signal by the first logic operation circuit based on the speed of the motor, to make the driving circuit control the main circuit to work normally or enter the safety state. In addition, the motor controller generates and outputs the second shutoff signal by the monitoring chip based on the working state or the output instruction of the microprocessor, and then outputs the second control signal by the second logic operation circuit based on the second shutoff signal and whether the DC bus voltage of the main circuit is in an overvoltage state, to make the driving circuit control the main circuit to stop receiving the first control signal and enter the safety state.