Motor Winding Temperature Estimation via Input Power
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Solution Overview
Problem
In synchronous motors, especially in low rotation states, temperature estimation of windings is inaccurate due to uneven heat distribution, leading to potential insulation deterioration, even with temperature sensors, as current flows predominantly in specific phases, causing high temperatures in parts of the motor.
Innovation Solution
A method for controlling motors that estimates the maximum temperature of windings based on input power in low rotation states and limits input power accordingly, using a transfer function to calculate the estimated maximum temperature and implement torque limitations to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are installed in the motor to measure winding temperature, then temperature measurement capability is improved, but device complexity and production cost increase
Solution Approach 1:
The patent replaces physical temperature sensors with an electrical measurement system that calculates winding temperature based on voltage and current measurements. The controller computes temperature using the relationship between input power, resistance, and heat generation, substituting mechanical sensor installation with computational estimation methods.
Solution Approach 2:
The patent introduces an intermediate calculation method that uses measurable electrical parameters (voltage, current, input power) as mediators to infer the difficult-to-measure winding temperature. Instead of directly measuring temperature, the system uses electrical quantities as intermediaries to estimate thermal state.
2Force
If current flows through specific phases to generate torque in low rotation state, then motor torque output is improved, but winding temperature distribution becomes uneven causing insulation deterioration
Solution Approach 1:
The patent performs preliminary temperature estimation before insulation deterioration occurs by continuously monitoring input power and calculating winding temperature in advance. The system estimates temperature rise based on input power magnitude and limits current proactively when temperature approaches dangerous levels, preventing insulation damage before it happens.
Solution Approach 2:
The patent implements a feedback control mechanism where the estimated winding temperature is continuously monitored and used to adjust the input power limits. When temperature reaches critical thresholds, the system reduces current or power automatically, creating a closed-loop control that prevents overheating while maintaining optimal torque production.
3Temperature
If input power is limited to prevent overheating, then winding temperature control is improved, but motor torque output and productivity decrease
Solution Approach 1:
The patent implements dynamic input power limiting where the temperature threshold and power limits are not fixed but adapt based on operating conditions. The system adjusts power limits in real-time according to the estimated temperature, rotation state, and thermal capacity of the windings, allowing maximum torque when cool and reducing power only when necessary to prevent overheating.
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 effectively prevents insulation deterioration by accurately estimating and managing temperature across windings, reducing the need for multiple temperature sensors and lowering production costs, while ensuring the motor operates within safe temperature thresholds.
Implementation Method 1
The windings of the respective phases generate heat when current flows
Implementation Method 2
a computation step of computing the maximum temperature of the winding having a phase that reaches the highest temperature among the windings of the plurality of phases in accordance with the power loss
Data Source
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AI summary
A method of controlling a motor is a method for controlling a motor having windings of a plurality of phases, including an estimation step of estimating the maximum temperature of the winding of a phase that reaches the highest temperature among the windings of the plurality of phases, in accordance with the magnitude of input power that is input to the motor, in the case where the motor is in a low rotation state, and a limiting step of limiting the input power on the basis of the maximum temperature estimated in the estimation step.