How to Choose an Appropriate Inverter for Motor
Source:
|
Author:lytrannet
|
Published time: 2019-06-02
|
33 Views
|
Share:
Frequency converter makes the motor drive system realize two desires: one is to make the motor run more efficiently; the other is to make the motor work under control, which also avoids manpower. But the problem facing engineers is: there are so many types of motor loads, and the performance requirements of the allocated converters vary greatly. How to choose the appropriate converter for the motor?
Frequency converter makes the motor drive system realize two desires: one is to make the motor run more efficiently; the other is to make the motor work under control, which also avoids manpower. But the problem facing engineers is: there are so many types of motor loads, and the performance requirements of the allocated converters vary greatly. How to choose the appropriate converter for the motor?
The selection of frequency converter should be considered according to the type of machinery, speed range, static speed accuracy and starting torque, so that it can be used easily and economically while meeting the requirements of technology and production.
Most of them are:
The size of the motor depends on the size of the frequency converter, sometimes a larger specification.
It is better to install AC reactor at the input end of the converter when the power factor of the high-power converter is low. One is to improve the power factor and the other is to suppress the high frequency harmonics. If frequent start, brake, to install brake unit and brake resistance.
If you need to reduce noise, you can choose water-cooled frequency converter.
If braking is needed, chopper and brake resistance should be selected.
If there is only DC power supply in the field, simple inverters (using DC power supply) can be selected to drive the motor.
Here are some issues we need to pay attention to when we choose frequency converter.
1. The purpose of frequency conversion; constant voltage control or constant current control.
2. The load type of frequency converter, such as vane pump or volume pump, pays special attention to the load performance curve, which determines the way of application.
3. Matching problem between frequency converter and load;
Voltage matching; the rated voltage of the converter is in accordance with the rated voltage of the load.
Current matching; Normal centrifugal pump, the rated current of the frequency converter is in accordance with the rated current of the motor. For special loads such as deep-water pumps, motor performance parameters are needed to determine the current and overload capacity of the converter with the maximum current.
Torque matching; this may occur with constant torque loads or deceleration devices.
4. When using frequency converter to drive high-speed motor, the output current value increases due to the small reactance of high-speed motor and the increase of high-order harmonics. Therefore, the capacity of the frequency converter used in high-speed motors is slightly larger than that of ordinary motors.
5. If the frequency converter wants to run with long cable, measures should be taken to restrain the influence of long cable on ground coupling capacitance, so as to avoid the insufficient output of the frequency converter. Therefore, in this case, the capacity of the frequency converter should be enlarged by one gear or the output reactor of the frequency converter should be installed at the output end of the converter.
6. For some special applications, such as high temperature and high altitude, the capacity of the converter will be reduced at this time, and the capacity of the converter should be enlarged in one gear.
For some occasions where motor motion control system is strictly required, it is necessary to accurately detect the effect of frequency converter selection. The direct method is to test the motor test system. However, in order to complete the overall test of frequency converter and motor system, higher requirements are put forward for motor test system, such as high bandwidth, high precision electrical parameter measurement, multi-channel synchronous test, etc.
English
