Electric Machine Stator Temperature Sensor Plausibility Check
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Solution Overview
Problem
Existing methods for diagnosing temperature sensor functionality in electric machines of motor vehicles are limited by the need for significant current flow over long periods to induce heat changes, making periodic plausibility checks infrequent and inefficient.
Innovation Solution
Increasing the current in the stator winding while maintaining constant torque to introduce additional energy and heat, allowing for a plausibility check of the temperature sensor at any time, using the integral of current and temperature change comparison for diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the current in the stator winding is increased to induce heat changes for temperature sensor diagnosis, then the frequency of plausibility checks can be improved, but the energy consumption and efficiency deterioration worsen
Solution Approach 1:
The patent applies dynamics by making the current increase temporary and conditional rather than continuous. The control device dynamically adjusts the current only when diagnostic conditions are met (sufficient time window, adequate starting temperature), and returns to normal operating current afterward. This dynamic approach enables frequent diagnostics while minimizing energy loss during non-diagnostic periods.
Solution Approach 2:
The patent implements periodic action through time windows for diagnosis. Instead of continuous current increase, the system periodically initiates diagnostic current increases only when specific conditions are satisfied (temperature threshold, sufficient time window availability). This periodic approach allows frequent plausibility checks while avoiding continuous energy waste, resolving the contradiction between diagnostic frequency and energy consumption.
2Reliability
If the current is increased to enable plausibility checks at any time, then the reliability of temperature monitoring is improved, but the efficiency of the electric drive deteriorates
Solution Approach 1:
The patent applies preliminary action by checking diagnostic conditions (temperature threshold, time window availability) before initiating current increase. The control device prepares by evaluating whether the stator temperature is sufficiently high and whether enough time remains in the current operating cycle to complete diagnosis without disrupting normal operation. This preliminary assessment ensures reliability improvements only when conditions permit, avoiding unnecessary efficiency losses.
Solution Approach 2:
The patent changes operating parameters (current magnitude, duration of current increase) based on detected temperature and timing conditions. When temperature is sufficiently high and time window is adequate, the system increases current for diagnosis; otherwise, it maintains normal operating current. This parameter adaptation allows the system to achieve reliable temperature monitoring while preserving drive efficiency under normal operating conditions.
3Temperature
If the plausibility check is performed only when large currents flow over long periods, then the energy available for heating is sufficient, but the frequency of diagnosis deteriorates
Solution Approach 1:
The patent applies partial action by increasing current only to the extent necessary for diagnosis rather than maintaining continuously high current. The control device determines a diagnostic current increase that is sufficient to produce measurable temperature changes within the available time window, but no greater than needed. This partial current increase provides adequate temperature change for reliable diagnosis while occurring frequently enough to improve diagnosis frequency compared to waiting for naturally occurring high-current periods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables frequent and efficient plausibility checks of temperature sensors without disrupting vehicle operation, ensuring timely detection of sensor functionality and minimizing energy wastage.
Implementation Method 1
the current in the stator winding is increased while maintaining constant torque of the electric machine, in order to increase the probability that the stator is heated
Data Source
AI summary
The invention relates to a method for operating an electric machine (4), in particular of a motor vehicle (1), having a stator (10) with at least one stator coil. The stator coil is energized in order to set a required torque of the electric machine (4), and a temperature of the stator (10) of the electric machine (4) is detected by means of a temperature sensor (12). The current flowing through the stator coil is monitored in order to plausibility-check the detected temperature. In order to plausibility-check the temperature, the current in the stator coil is increased while maintaining the same torque, and the temperature is monitored for a temperature increase.