Electric motor stator winding temperature estimation
First Claim
1. A method for controlling a torque command to prevent overheating of one or more of a plurality of phases of a permanent magnet motor, the method comprising the steps of:
- determining whether a detected speed of the permanent magnet motor is less than a first predetermined speed;
calculating a copper loss of each of the plurality of phases of the permanent magnet motor in response to an alternating current (AC) root mean square (RMS) current of each of the plurality of phases;
calculating first thermal impedances for each of the plurality of phases in response to the copper loss of each of the plurality of phases;
estimating a stator temperature of each of the plurality of phases in response to the first thermal impedances for each of the plurality of phases with respect to a thermal neutral when the detected speed of the permanent magnet motor is less than the first predetermined speed; and
derating the torque command in response to the stator temperature of one or more of the plurality of phases.
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Accused Products
Abstract
A temperature estimation controller and methods are provided for controlling a torque command to prevent overheating of one or more of a plurality of phases of a permanent magnet motor. The temperature estimation controller includes a low speed temperature estimation module, a transition module and a temperature dependent torque command derater block. The low speed temperature estimation module determines a stator temperature of each of a plurality of phases of the permanent magnet motor in response to first thermal impedances measured for each of the plurality of phases with respect to a thermal neutral. The transition module is coupled to the low speed temperature estimation module and outputs the stator temperature of each of a plurality of phases of the permanent magnet motor as determined by the low speed temperature estimation module when a detected speed of the permanent magnet motor is less than a first predetermined speed. The temperature dependent torque command derater block is coupled to the transition module and derates the torque command in response to the stator temperature of one or more of the plurality of phases.
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Citations
18 Claims
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1. A method for controlling a torque command to prevent overheating of one or more of a plurality of phases of a permanent magnet motor, the method comprising the steps of:
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determining whether a detected speed of the permanent magnet motor is less than a first predetermined speed; calculating a copper loss of each of the plurality of phases of the permanent magnet motor in response to an alternating current (AC) root mean square (RMS) current of each of the plurality of phases; calculating first thermal impedances for each of the plurality of phases in response to the copper loss of each of the plurality of phases; estimating a stator temperature of each of the plurality of phases in response to the first thermal impedances for each of the plurality of phases with respect to a thermal neutral when the detected speed of the permanent magnet motor is less than the first predetermined speed; and derating the torque command in response to the stator temperature of one or more of the plurality of phases. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A temperature estimation controller for a permanent magnet motor comprising:
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a low speed temperature estimation module for estimating a stator temperature of each of a plurality of phases of the permanent magnet motor in response to first thermal impedances calculated for each of the plurality of phases with respect to a thermal neutral, wherein the low speed temperature estimation module; receives a coolant temperature signal; calculates a second thermal impedance with respect to the thermal neutral in response to the coolant temperature signal; and estimates the stator temperature of each of the plurality of phases of the permanent magnet motor in response to first temperature rises due to corresponding ones of the first thermal impedances and a second temperature rise due to the second thermal impedance; a transition module coupled to the low speed temperature estimation module and outputting the stator temperature of each of the plurality of phases of the permanent magnet motor as determined by the low speed temperature estimation module when a detected speed of the permanent magnet motor is less than a first predetermined speed; and a temperature dependent torque command derater block coupled to the transition module and derating a torque command in response to the stator temperature of one or more of the plurality of phases. - View Dependent Claims (9, 10, 11, 12)
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13. An electric motor system comprising:
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a permanent magnet electric motor including a plurality of phases; an inverter coupled to the plurality of phases of the permanent magnet electric motor and providing electric control therefor; a coolant coupled to the permanent magnet electric motor for reducing a temperature thereof during operation; a resolver coupled to the permanent magnet electric motor for detecting a speed thereof and generating a detected speed signal in response to the speed of the permanent magnet electric motor; a thermistor coupled to one of the plurality of phases for determining a temperature thereof and generating a phase temperature signal in response to the temperature of the one of the plurality of phases; a coolant temperature detector coupled to the coolant for determining a temperature thereof; and a temperature estimation controller coupled to the inverter, the coolant temperature detector, and the resolver for; calculating first thermal impedances for each of the plurality of phases based on a copper loss of each of the plurality of phases; determining a second thermal impedance of a thermal neutral with respect to a coolant temperature signal received from the coolant temperature detector; estimating a stator temperature of each of the plurality of phases of the permanent magnet electric motor in response to first temperature rises due to corresponding ones of the first thermal impedances with respect to the thermal neutral and a second temperature rise due to the second thermal impedance; and derating a torque command to generate a derated torque command in response to the stator temperature of one or more of the plurality of phases when the detected speed signal is less than a first predetermined speed, wherein the inverter provides electric control for the plurality of phases of the permanent magnet electric motor in response to the derated torque command. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification