Investigating the influencing factors of electric dynamometer motor in Shaoyang College of Higher Education, 2000, Department of Electrical Engineering, Department of Electrical Engineering, Shaoyang College, Shaoyang, Hunan 4220, China The main news is to discuss the performance of the non-sinusoidal dynamometer motor of the input voltage of the variable frequency power supply, and propose improvement. Adverse effects measures AC frequency conversion motor-type electric dynamometer is a new type of dynamometer that appeared in the 1980s. It is the product of electromechanicalization technology, and it is the computer technology of motor design, power electronics technology, and other technical aspects. The comprehensive application of knowledge, its research results have a strong application value, its technical performance indicators are more than the current world-recognized most advanced people AC frequency conversion electric dynamometer, belonging to, technology products, due to its price Relatively cheap, it is about 1314. Therefore, it is more vital in the current economic environment. It also has the strength to participate in the international competition. The electric dynamometer is mainly composed of the device control device and the dynamometer motor. A full-featured variable frequency speed control system with the main vertical as a high-level test equipment for torque and power. TJ near sine wave, to achieve the purpose of weakening the harmonics, in the control device, the reasonable choice of pulse width modulation strategy, so that the internal harmonics of the variable frequency power supply is greatly suppressed. The dynamometer can be designed as an anti-harmonic old-step motor as much as possible. The motor still has better performance under the condition of the variable frequency power supply with the constant harmonic component.
1 Variable frequency power supply is the main harmonic source of electricity. The frequency conversion device is the main non-sinusoidal power receiving device of the power grid. The power source taken from the AC power system is non-sinusoidal, and its voltage waveform can be decomposed into the fundamental wave according to the Fourier series. And series of harmonics of different frequencies and amplitudes, these harmonics will bring the following series of adverse effects to the motor.
Ll pulse vibration torque due to the non-sinusoidal input voltage of the variable frequency power supply, according to the fundamentals of the Freund's decomposition and the series of higher harmonics will generate respective voltages in the motor to generate 5,1 reverse rotating magnetic field and torque, The 7th harmonic voltage produces +7,1 and the forward rotating magnetic field and torque are maximum. They will respectively interact with the rotating magnetic field of the stator 10 to generate the pulse torque of 61. These 61 pulse torque values Although it is not large, it will cause the output torque of the dynamometer motor to pulsate, especially in the light load and low speed operation, the influence of torque ripple is more obvious, resulting in uneven motor speed and stepping feeling, causing vibration of the dynamometer motor. And noise.
1.2 Various loss increases The high-order harmonics generated by the waveform distortion of the variable-frequency power supply and the spatial harmonics caused by the cogging of the motor are superimposed, so that the magnetic flux in the air gap of the motor contains higher harmonics. Harmonics will cause the mechanical loss and additional loss of the copper consumption of the dynamometer motor, although the total increase of the core loss caused by the time harmonic flux is negligible in the total iron loss, but the end leakage The leakage flux of the pass and chute may produce a considerable core loss at the harmonic frequency, and the skin effect will increase the resistance of the stator and the rotor, resulting in an increase in copper consumption, and the mechanical loss will increase with the speed. However, when the power frequency is rising, the additional loss is also increased, so the efficiency of the motor is reduced. 5 The output power is reduced, the temperature rise of the motor is also increased, and the dynamometer performance is degraded. , 1.3 voltage imbalance occurs in the variable frequency power supply, under normal circumstances, the phase voltage applied to the dynamometer motor is balanced, but due to the trigger failure of various switching components and the characteristics of the rectifier components and control components of each phase, It may cause the voltage imbalance of the dynamometer motor to occur at a certain moment, and the shaft voltage caused by the imbalance of the magnetic circuit of the motor and the high-frequency voltage on the rotor may generate static electricity in a capacitor formed by the bearing oil film as a medium. The accumulation of the lotus. A large shaft card is generated on the shaft so that the generated current will circumvent the oil flow between the shaft and the shaft 1. Oil stocks are destroyed due to large turbulence, shortening bearing life, and jeopardizing the safe operation of the motor. 2 Common measures to improve the bad factors. The dynamometer motor needs to be powered by a special variable frequency power supply to ensure the static of the motor. Characteristics and speed range, so some common measures should be taken to improve the bad factors.
From the optimal starting point of the system, the choice of the rated value of the voltage frequency power efficiency of the dynamometer motor is not limited by the power frequency grid.
When the air gap flux is kept constant during operation, the maximum torque does not substantially change.
3 The motor should have sufficient rigidity to gram and pulse torque. For current-type inverters, the leakage reactance of the motor should be small; for voltage-type inverters, the leakage reactance of the motor should be large.
In order to reduce various losses, the motor core should be made of high-quality and thin galvanized steel sheets. The stator or rotor groove must be skewed, and the groove fit and groove shape should be correctly selected. It is best to use forced air cooling.
3 Conclusion AC variable frequency speed control dynamometer motor as an important component of AC variable frequency speed control electric dynamometer system, because it requires dedicated variable frequency power supply, its design principle can not be equivalent to ordinary asynchronous motor, should be based on electronic and motor Part of the technical and economic rationality is considered together and determined by the overall best requirements.
1 Hu Wei, 7. Modern exchange adjustments, 1. North. 1; The machinery industry is out of the company. 1999 2 Tibetan Yingjie. Frequency control elbow of AC motor. Beijing China Railway Publishing House, 1984 3, Liquan and so on. 35 dynamic power system program evaluation analysis 1.1992 4 Cheng Li mining. Discussion on the electromagnetic calculation and design of the inverter-controlled asynchronous motor. Electronic Technology Magazine. 445 Siemens 6870 Inverter User Manual Responsible Editor Qian Guanmin

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