Electric Machine Control Plausibility Check for Safe Shutdown
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Solution Overview
Problem
Existing methods for controlling electric machines in electric vehicles are prone to errors during power shutdown, particularly in hybrid or electric vehicles, where safe disconnection from energy supply is critical due to faster torque buildup and lack of mechanical components for reverse gear, leading to potential unsafe operating states.
Innovation Solution
A control method that records control signals and operating states, performs a plausibility check for discrepancies, and disconnects the electric machine from its energy supply using a switching device if irregularities are detected, ensuring a safe operating state by comparing torque, speed, or vehicle acceleration parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the switch-off path is tested only at the beginning or end of a driving cycle, then the test procedure is simple, but the switch-off mechanism may become defective and undetected during long running cycles
Solution Approach 1:
The patent applies preliminary action by continuously monitoring the actual operating state (torque, speed) during the entire driving cycle, not just at the beginning or end. This continuous preliminary detection ensures that any deviation from the expected zero-state during run-on mode is immediately identified, making the test effective regardless of cycle length.
Solution Approach 2:
The patent implements feedback by comparing the actual operating state (measured torque and speed) with the expected state (zero torque and speed during run-on). This continuous feedback loop provides definitive information about whether the switch-off mechanism is functioning correctly, resolving the reliability issue while maintaining simple test logic.
2Ease of operation
If the status of power output stages is read back via SPI BUS, then the switch-off path can be tested, but this does not provide definitive statement whether actuators can really be switched off
Solution Approach 1:
The patent replaces the electronic status reading method (SPI BUS) with direct physical measurement of the operating state (torque and speed sensors). This substitution provides definitive verification of actual switch-off performance rather than relying on electronic status signals that may be misleading.
Solution Approach 2:
The patent introduces an intermediary plausibility check that compares measured operating parameters (torque, speed) with expected values. This intermediary verification layer bridges the gap between simple status reading and definitive switch-off confirmation, providing reliable verification while maintaining ease of operation.
3Adaptability or versatility
If the drive control unit receives switch-off request via CAN BUS from vehicle management control unit, then vehicle control is integrated, but the switch-off mechanism becomes more complex and error-prone
Solution Approach 1:
The patent extracts the critical safety function from the complex multi-layer control system and implements it directly in the drive control unit through continuous monitoring of operating state. This extraction ensures that the essential switch-off verification function remains simple and reliable even within the integrated vehicle control architecture.
Solution Approach 2:
The drive control unit performs self-verification by continuously monitoring its own operating state (torque, speed) and comparing it with expected values. This self-service approach simplifies the overall system by making the control unit self-checking, reducing reliance on external verification mechanisms while maintaining integration benefits.
Data Source
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AI summary
The invention relates to a method for controlling an electric machine (5) of an electric vehicle. According to said method, the control signals for controlling the electric machine (5) are captured, the operational state of the electric machine (5) is then stored and the stored operational state of the electric machine (5) is checked for plausibility with the control signals guided to the electric machine (5). The connection between the electric machine (5) and the energy supply device (6) is interrupted if an irregular operational state of the electric machine (5) appears. The invention also relates to a control device for an electric machine (5).