|作者: lytrannet|发布时间: 2019-06-02|447 次浏览Source:|Author: lytrannet|Published: 2019-06-02|447 views分享到:|Share to:
The inverter enables the motor drive system to realize two wishes. One is to allow the motor to achieve more efficient operation; the other is to allow the motor to achieve controllable working conditions, which also avoids manpower. But the question before the engineer is: there are so many types of motor loads, and the performance requirements of the frequency converters are very different. How to choose the right frequency converter for the motor?
The inverter enables the motor drive system to realize two wishes. One is to allow the motor to achieve more efficient operation; the other is to allow the motor to achieve controllable working conditions, which also avoids manpower.But the question before the engineer is: there are so many types of motor loads, and the performance requirements of the frequency converters are very different. How to choose the right frequency converter for the motor? The selection of the inverter should be considered according to the type of machine, speed range, static speed accuracy, starting torque, etc., so that it can be easy to use and economical while meeting the process and production requirements.
Most of them are: The bigger the motor, the bigger the inverter, and sometimes a bigger size. High-power inverters have a low power factor. It is best to install AC reactors at the input end of the inverter.This is to increase the power factor and to suppress high-frequency harmonics.If frequently starting and braking, install braking unit and braking resistor. If you need to reduce noise, you can choose a water-cooled inverter; If braking is required, a brake chopper and a braking resistor are required. If the site has only DC power, you can choose a simple inverter product (using DC power) to drive the motor.
Here are some of the issues we need to pay attention to when selecting a frequency converter. 1. The purpose of frequency conversion; constant voltage control or constant current control. 2. Load type of the inverter; such as vane pump or positive displacement pump. Pay special attention to the performance curve of the load. The performance curve determines the method and method of application. 3. The matching problem between inverter and load; Voltage matching; the rated voltage of the inverter matches the rated voltage of the load. Current matching; for ordinary centrifugal pumps, the rated current of the inverter is consistent with the rated current of the motor.For special loads, such as deep-water pumps, you need to refer to the motor performance parameters to determine the inverter current and overload capacity with the maximum current. Torque matching; this situation may occur under constant torque load or with a reduction gear.
4. When the inverter is used to drive a high-speed motor, the output current value increases due to the small reactance of the high-speed motor and the increase of higher harmonics.Therefore, the selection of the inverter used for high-speed motors has a slightly larger capacity than the selection of ordinary motors. 5. If the inverter needs to run with a long cable, measures must be taken to suppress the influence of the long cable to the ground coupling capacitor to avoid insufficient output of the inverter, so in this case, the capacity of the inverter should be enlarged by one gear or An output reactor is installed at the output end. 6. For some special applications, such as high temperature and high altitude, the inverter will be derated at this time, and the inverter capacity must be enlarged by one stop. For some occasions where the motor motion control system is strictly required, it is necessary to accurately detect the effect of the selection of the inverter. The direct method is to test through the motor test system.However, in order to complete the overall test of the inverter and the motor system, higher requirements are placed on the motor test system, such as high-bandwidth, high-precision electrical parameter measurement, and multi-channel synchronous testing.