1, the efficiency and the problem of temperature rise of the motor in either in the form of a frequency converter, both in the operation of the different degree of harmonic voltage and current, make the motor in non-sinusoidal voltage, power flow operation. Rejected materials is introduced, at the current widely used sine wave type PWM inverter as an example, the basic is zero, the low-order harmonic than the rest of the carrier frequency about twice as large as the higher harmonic components as follows: 1 (2 uU for the modulation ratio)。 PWM pulse width modulation, is a way to use the digital output of the microprocessor to control the analog control technology. PWM with its simple, flexible control, high efficiency and good dynamic response and are widely used in from measurement, communication to power control and transform in many areas. PWM is the term of type switch regulated power supply. Which are classified according to the voltage control mode, in addition to the PWM type, type and PFM and PWM, PFM hybrid. Now a lot of micro controller have PWM controller. Can lead to higher harmonic motor stator copper loss, rotor copper (Aluminum)Consumption, iron loss and the increase of the additional loss, the most significant is the rotor copper (Aluminum)Consumption. Because is close to the base wave frequency corresponds to the synchronous speed of rotation, therefore, higher harmonic voltage to a larger slip cutting rotor after conducting bar, will produce very big rotor loss. In addition, also should be considered because of skin effect produced by the additional copper loss. These losses will make motor extra heat, low efficiency, output power decreases, and such as ordinary three-phase asynchronous motor running in the inverter output non-sinusoidal conditions, its temperature to increase 10% in general-20% power source is to provide electronic equipment power device, also known as power supply, it provides all parts needed electricity in the computer. 2, at present middle and small converter motor insulation strength problem, many are using the PWM control mode. He is about several thousand to more than 10 KHZ carrier frequency, which makes the motor stator winding to withstand high voltage build-up rate, equivalent to impose great impulse voltage gradient on motor, the motor of the turn-to-turn insulation withstand ordeal. In addition, the rectangular produced by PWM inverter chopper superposition of impulse voltage on the motor running voltage, would pose a threat to ground insulation of motor, the ground under the repeated impact of high voltage insulation can accelerate ageing. Three, harmonic electromagnetic noise and vibration of common induction motor using frequency inverter power supply, can make the electromagnetic, mechanical, ventilation and other factors caused by the vibration and noise becomes more complicated. Frequency conversion power harmonic and motor electromagnetic part contains all of the time the inherent space harmonic interference each other and form all kinds of electromagnetic vibration force. When the electromagnetic wave frequency and motor of the body's natural vibration frequency is consistent or close to, will produce resonance phenomenon, so as to increase the noise. Due to the motor operating frequency range wide, wide speed change range, all kinds of the electromagnetic wave frequency is difficult to avoid the components of the motor of the inherent vibration frequency. 4's ability to adapt to frequent starting, braking, motor with inverter power supply, motor can under low frequency and voltage start, in the form of no impact current and frequency converter is available for all kinds of brake mode for rapid braking, create conditions for the realization of the frequent starting and braking, and the mechanical system and electromagnetic system of the motor is in circulation under the action of alternating force, brings to the mechanical structure and insulation structure fatigue and accelerated aging problem. 5, low speed problem of cooling the first, the impedance of the asynchronous motor is not ideal, when frequency is bottom, the power loss caused by high order harmonic. Second, when ordinary asynchronous motor speed to reduce again, cooling air volume and speed of three proportional to reduce, cause the low speed of a motor cooling conditions deteriorate, a sharp increase in temperature is difficult to realize the constant torque output. The article links: industrial control network (The station)http://www。 gkzhan。 com/News/Detail/29540。 HTML the main products: stepper motor, brushless motor, servo motor, stepping motor drive, brake motor, linear motor and other kinds of models of the stepper motor, welcome to inquire. Telephone:
