Method for measuring rotor copper loss caused by harmonics under no-load condition of variable-frequency motor

A technology of variable frequency motor and rotor copper loss, which is applied in the direction of measuring electricity, measuring electrical variables, motor generator testing, etc., can solve the problem that the rotor copper loss is not separated, and achieve the effect of accurate calculation value

Active Publication Date: 2019-02-22
XI AN JIAOTONG UNIV
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AI Technical Summary

Problems solved by technology

However, the rotor copper loss caused by harmonics (time harmonics and space harmonics) has not been separated, and there is an urgent need for a method to measure the rotor copper loss caused by harmonics in the case of no-load frequency conversion motors

Method used

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Embodiment Construction

[0024] The present invention will be described in further detail below in conjunction with specific embodiments.

[0025] A method for measuring the copper loss of the rotor caused by harmonics under the condition of no-load of the variable frequency motor of the present invention comprises the following steps:

[0026] 1) The frequency conversion motor under test is coaxially connected with an adjustable-speed accompanying motor, and the accompanying motor is used to drive the frequency conversion motor under test; the speed regulation range of the accompanying motor includes the synchronous speed n corresponding to the fundamental wave of the frequency conversion motor under test ;

[0027] 2) The frequency conversion motor under test is powered by its matching frequency conversion power supply, and the PWM or square wave voltage of a certain frequency and size required by the frequency conversion motor under the rated condition is provided according to the normal allowable ...

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Abstract

The invention discloses a method for measuring the rotor copper loss caused by harmonics under the no-load condition of a variable-frequency motor. A partner-testing motor drags a tested variable-frequency motor to realize speed synchronization, a variable frequency power supply provides a voltage for the tested variable-frequency motor under a normal no-load work condition, input power, a statorvoltage, a stator current and stator end resistance at the time are recorded, and a stator copper loss value and a lossPL1 except the stator copper loss value are calculated; with an empty-slot rotoriron core, the same experiment is carried out again after assembling, so that a loss PL2 except the stator copper loss value is obtained; and a rotor copper loss Phcu2 that is caused by harmonics andcorresponds to a no-load voltage U1 of the tested variable-frequency motor is equal to a difference between the lossPL1 and the loss PL2. According to the invention, the rotor copper losses caused byharmonics are measured by dragging the rotor of the variable-frequency motor at the synchronous speed; and only harmonic induction currents instead of fundamental currents exist in the rotor guide barand the end ring, so that the pure harmonic rotor copper loss of the variable-frequency motor under the ideal no-load condition is obtained.

Description

technical field [0001] The invention belongs to the technical field of loss detection of asynchronous motors, in particular to a method for measuring copper loss of a rotor caused by harmonics under the condition of no-load of a variable frequency motor. Background technique [0002] Due to excellent running performance and energy saving, variable frequency motors are widely used in various fields. However, due to the application of frequency conversion technology, a certain amount of time harmonics will be introduced into the stator winding of the motor, and there will also be space harmonics in the air gap magnetic field. When the core loss curve of the motor is obtained through the no-load experiment of the fundamental frequency sine wave power supply, it is considered that the harmonic content is small, that is, the rotor copper loss caused by the harmonic is negligible. Compared with the basic frequency sine wave power supply, the frequency conversion power supply intr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/34
CPCG01R31/34G01R31/346
Inventor 刘新正李浩杰陈文李志恒李鹏王娟
Owner XI AN JIAOTONG UNIV
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