Motor Magnet Temperature Estimation from Winding Current Response
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Solution Overview
Problem
Existing methods for determining magnet temperature in electric motors, especially synchronous motors, are complex, costly, and require the motor to be rotating and the rotor position to be known, making them difficult to implement.
Innovation Solution
A temperature determination method involving test and normal operations where voltages are applied to motor windings at specific angles to measure current values, which are then compared to determine the magnet temperature without needing rotor position information or motor rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are installed on the motor rotor to measure magnet temperature, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses current values as an intermediary parameter to indirectly determine magnet temperature. Instead of directly measuring temperature with sensors on the rotor, the method measures electrical current values during voltage application and compares them against reference data to infer temperature, thus avoiding complex sensor installation while achieving temperature determination
Solution Approach 2:
The patent replaces the physical temperature sensing system with an electrical measurement system. By applying voltages and measuring resulting current values, the method substitutes mechanical/thermal contact measurement with non-contact electrical measurement, eliminating the need for physical temperature sensors on the rotor
2Measurement precision
If EMF evaluation or field current signal methods are used to determine magnet temperature, then measurement precision is improved, but ease of operation deteriorates due to rotation and rotor position requirements
Solution Approach 1:
The patent creates reference data (first current values) during test operations at known temperatures before normal operation. This preliminary characterization allows the system to determine temperature during normal operation by simply comparing current values without needing to perform complex real-time calculations or know rotor position, simplifying the normal operation process
Solution Approach 2:
Instead of using temperature measurements to determine operational parameters, the patent inverts the approach by using electrical current measurements (caused by applied voltages) to determine temperature. This reversal eliminates the need for the motor to be rotating or for rotor position information, as the measurement works in both stationary and rotating conditions
3Measurement precision
If torque measuring devices and torque estimation devices are used to estimate magnet temperature, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential measurement needed for temperature determination - the current value during voltage application. By taking out just this single measurement parameter and comparing it against reference data, the method eliminates the need for complex torque measuring devices and multiple estimation algorithms, achieving temperature determination with minimal measurement equipment
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
Accurately determines magnet temperature with reduced complexity and cost, allowing for precise torque calculations by comparing current values measured during test and normal operations.
Implementation Method 1
applying a first voltage U1 to at least one test winding (6) of a test motor (7)... applying a second voltage U2 to at least one motor winding (16)... determining first current values I1... determining second current values I2
Data Source
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AI summary
The invention relates to a temperature determination method (1) for magnet temperatures on magnets (2) of electric motors (3), having steps in a test mode (4): applying (5) a first voltage (U1) to at least one test winding (6) of a test motor (7) with test magnets (11) for impressing (8) a first voltage-time area (9) at first angles (Φ1) of a test motor rotating field (10), the test magnets (11) being subject to at least one predefined magnet temperature (TMV), ascertaining (12) first current values (I1) at the first angles (Φ1) and storing (13) the first current values (I1) on the basis of the at least one predefined magnet temperature (TMV), and having steps in a normal mode (14): furthermore applying (15) a second voltage (U2) to at least one motor winding (16) of an operations motor (17) with motor magnets (18) for furthermore impressing (19) a second voltage-time area (20) at second angles (Φ2 ) of a motor rotating field (26), the motor magnets (18) having an operation-dependent magnet temperature (TMN), furthermore determining (21) second current values (I2) at the second angles (Φ2), furthermore storing (22) the second current values (I2) on the basis of the operation-dependent magnet temperature (TMN) and determining the temperature (23) of the operation-dependent magnet temperature (TMN) by comparing (24) at least one of the second current values (I2) of the operation-dependent magnet temperature (TMN) with at least one of the first current values (I1) of the at least one predefined magnet temperature (TMV).