Rotor Temperature Estimation in Wind Turbine Generators
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Solution Overview
Problem
Conventional methods for assessing rotor temperature in permanent magnet synchronous machines, especially in fault-tolerant operating modes or with reduced converter operation, are inaccurate and conservative, leading to potential over-heating and power production losses, as they rely on single temperature sensors or simplistic offset calculations.
Innovation Solution
A method using measured electrical quantities to estimate rotor temperature, incorporating a flux model with reference flux linkage values and voltage measurements to derive an estimated flux linkage value, allowing for the identification of rotor hotspot temperature and sensor integrity, enabling optimized thermal management and continuous operation without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional temperature sensor methods are used, then the system is simple, but the measurement precision deteriorates in fault-tolerant operating modes
Solution Approach 1:
The patent introduces an intermediary estimation method that uses electrical measurements (voltages and currents) as mediators to infer rotor temperature indirectly through a thermal model, bypassing the need for direct temperature sensor readings in fault-tolerant modes
Solution Approach 2:
The patent replaces the mechanical/physical temperature sensor system with an electrical-based estimation system that uses electrical measurements and thermal models to determine rotor temperature, eliminating dependency on physical temperature sensors
2Device complexity
If a single temperature sensor is used, then the device complexity is low, but the reliability deteriorates when the sensor fails
Solution Approach 1:
The system uses its own electrical measurements (voltages and currents) to self-diagnose and self-correct temperature measurement issues, enabling continuous operation without external redundant sensors by estimating temperature from operational electrical data
Solution Approach 2:
The patent introduces an intermediary estimation method that uses electrical measurements (voltages and currents) as mediators to infer rotor temperature indirectly through a thermal model, bypassing the need for direct temperature sensor readings in fault-tolerant modes
3Reliability
If conservative offset calculations are used, then the rotor is protected from overheating, but the power production is reduced
Solution Approach 1:
The patent implements a dynamic thermal model that adapts to changing operating conditions (load, speed, cooling) to provide real-time accurate temperature estimation, replacing static conservative offsets with dynamic, condition-based temperature assessment that optimizes power production while maintaining protection
Solution Approach 2:
The patent changes the approach from using fixed conservative temperature offsets to using variable temperature estimates based on actual electrical measurements and thermal model parameters, allowing the system to operate closer to true temperature limits without excessive derating
4Measurement precision
If multiple temperature sensors are installed, then the measurement precision improves, but the device complexity and cost increase drastically
Solution Approach 1:
The patent segments the temperature measurement function into multiple electrical measurement points (voltages and currents) that collectively provide temperature information through the thermal model, replacing the need for multiple physical temperature sensors
Solution Approach 2:
The patent replaces the mechanical/physical temperature sensor system with an electrical-based estimation system that uses electrical measurements and thermal models to determine rotor temperature, eliminating dependency on physical temperature sensors
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
This approach provides accurate and robust rotor temperature estimation, enabling continuous operation and maximum power production while protecting the magnets from over-heating, even in fault-tolerant modes, and reduces the need for redundant sensors and conservative power derating.
Implementation Method 1
providing as a flux model temperature dependent reference flux linkage values for different rotor temperature values and multiple current values of an operating winding set
Data Source
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AI summary
It is described a method of assessing rotor temperature (Tpm) during operation of a permanent magnet synchronous machine (13), comprising a stator having at least one winding set (15, 17), in particular multiple winding sets, the method comprising: providing reference flux linkage values (psi*, 97) for different rotor and stator temperature values and current values (Is) of an operating winding set (15, 17); measuring an actual rotor temperature value (T1pm); measuring an actual stator temperature value (T1stator); measuring an actual current value (Is) of an operating winding set; deriving and storing reference flux linkage values for a given set of operating conditions (eq. (4) or (10), 93), in particular, by means of a reference run (95); deriving (eq. (6) or (9) or (11)) a reference flux linkage value (psi*, 97) (for the measured actual rotor and stator temperature values and the measured actual current value of the operating winding set) using the flux model; obtaining a voltage value (Vabc or Vdq*, 103) related to at least one winding set; deriving (eq. (5) or (10)) an estimated flux linkage value (107) based on the obtained voltage value (103) and/or current and/or machine parameters; deriving (eq. (7)) a rotor temperature offset based on the difference between the reference flux linkage value (97) for the measured actual rotor temperature value and the estimated flux linkage value (107); assessing the rotor temperature based on the rotor temperature offset.