Vehicle Motor Control Unit with Three-Processor Output Validation
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Solution Overview
Problem
The increasing number of control inputs for electric drive motors in vehicles leads to elevated motor control unit (MCU) response times, affecting user experience and potentially violating stringent vehicle functional safety requirements due to latency issues in processing these inputs.
Innovation Solution
A motor control unit comprising three processors: a third processor calculates torque based on actuation demands and provides it to a first processor, which determines control outputs along with vehicle control inputs, while a second processor validates these outputs by comparison, utilizing dedicated communication buses to reduce latency and enhance safety functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of control inputs for the electric drive motor is increased to improve vehicle functionality and control precision, then the control capability and safety are improved, but the response time of the motor control unit deteriorates due to increased processing latency
Solution Approach 1:
The patent divides the motor control unit into three separate processors with specialized functions: a first processor for receiving control inputs and determining control outputs, a second processor for validating control outputs through independent calculation, and a third processor for calculating torque based on actuation demands. This segmentation allows each processor to handle specific tasks efficiently, reducing overall processing latency while maintaining safety through distributed validation
Solution Approach 2:
The third processor performs preliminary torque calculation based on actuation demands before the control output validation step. By pre-calculating torque values and making them available to the first processor, the system reduces the processing time required during critical control decisions, thereby improving response time without compromising safety validation
2Device complexity
If a single processor is used in the motor control unit to simplify the system structure, then the device complexity is reduced, but the response time deteriorates due to the increasing number of control inputs that must be processed sequentially
Solution Approach 1:
Instead of using a single processor that must handle all control inputs sequentially, the patent segments the processing into three specialized processors that can operate in parallel. The first processor handles control input reception and output determination, the second processor independently validates outputs, and the third processor pre-calculates torque values. This parallel architecture dramatically increases processing speed while keeping each individual processor relatively simple
Solution Approach 2:
Each processor in the three-processor system is designed with multi-functionality to handle multiple aspects of motor control. The first processor both receives control inputs and determines control outputs, the second processor validates control outputs through independent calculation, and the third processor calculates torque and provides it to the first processor. This multi-functionality reduces the need for additional dedicated components, balancing complexity with performance
3Reliability
If validation of control outputs is performed to improve safety, then the reliability is improved, but the processing time increases due to the additional validation step
Solution Approach 1:
The second processor performs validation by independently calculating control outputs based on the same control inputs that the first processor uses. This preliminary independent calculation allows for rapid validation without adding significant processing time, as the second processor works in parallel with the first processor rather than sequentially after it
Solution Approach 2:
The validation mechanism uses a copying approach where the second processor creates an independent copy of the control logic to verify the first processor's outputs. Instead of complex validation algorithms that would increase processing time, the system copies the essential calculation logic and compares results, providing robust safety validation with minimal time penalty
Data Source
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AI summary
A motor control unit for a vehicle comprising an electric drive motor, the motor control unit comprising a first processor, a second processor and a third processor, in which: the third processor is configured to: receive an actuation demand for the vehicle; calculate a torque for the motor in dependence on the actuation demand; and provide the calculated torque to the first processor; the first processor is configured to: receive the calculated torque and a control input of the vehicle; and determine a first control output for the electric drive motor in dependence on the calculated torque and the control input; and the second processor is configured to: receive the first control output from the first processor and the control input of the vehicle; calculate a second control output for the motor in dependence on the control input; and validate the first control output by comparison to the second control output.