When the high-power motor starts, the current is large, which will cause the grid voltage to be seriously shaken, in order to deal with this problem, the general requirements for speed regulation are not high, and the soft engine can be used to reduce the voltage and start. However, the drop in the starting current when the step-down is started will also cause the starting torque to drop significantly, so it is not suitable for starting with rated load, and it is generally suitable for no-load or light-load starting.
When the motor needs to be started with load or has high requirements for speed regulation, the inverter is generally selected to start, which can reduce the starting current under the premise of ensuring a larger starting torque.
In addition, the step-down and constant voltage frequency ratio (constant air-gap magnetic flux) can be speed regulation, but the step-down speed regulation will make the mechanical characteristics of the motor softer, and the speed regulation scale is small. The speed regulation scale of constant voltage frequency ratio speed regulation is large, and the mechanical characteristics of the motor are hard.
The constant voltage frequency ratio speed regulation has so many excellent special effects, why not use it on a large scale, the answer is that the cost of the soft engine is very low, the AC power voltage regulation circuit can be realized, and the high-power inverter is expensive.
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(3) ...
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E.bC
Reynolds inverter fault phenomenon/type:
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