Reasons and solutions for frequency adjustment failure of frequency converters

The frequency of the frequency converter cannot be adjusted up. If there is no hardware damage, it is usually caused by the maximum torque output of the frequency converter being less than the load lifting torque. To put it bluntly, the frequency converter has poor load carrying capacity.

1. Acceleration time too short

In theory, the longer the acceleration time, the stronger the ability to improve with load. If the set acceleration time is too short, some frequency converters may display overcurrent or overload overheating alarms, but some may not display them, just stuck in a certain frequency range.

2. V/F ratio too large

Some frequency converters, also known as torque boost, can sometimes fail to start normally if this parameter is set too high. Reducing it appropriately can solve the problem

3. Vector control parameter mismatch

In vector control mode, the internal resistance, inductance, and other parameters of the motor need to be accurately measured and coordinated with the vector parameters of the frequency converter. After running for a period of time, the motor parameters overheat and cause deviation, which can cause excessive current and prevent the motor from starting normally. The frequency may also get stuck at a certain point, and re optimizing the parameters can solve the problem.

4. The maximum frequency and maximum frequency settings are too low

Generally, these two parameters are set to the maximum value, but it is not ruled out that some careless electricians have changed these two parameters, which can also cause the inability to increase the frequency.

5. Some special occasions require pairing of parameters

In some situations, the minimum frequency cannot be set too low. For example, in a constant pressure water supply system, when the minimum frequency is set to 0Hz, when the water pump pressure is low and exceeds the starting frequency of the frequency converter, the frequency converter begins to accelerate, but the pressure cannot be increased. The frequency converter frequency cannot be increased to 50Hz, only around 38Hz. The PID is repeatedly set and adjusted, but the frequency cannot be increased. Only by setting the minimum frequency of the frequency converter to around 15-20Hz can the acceleration of the frequency converter be met, and the water pump can be kept at a constant pressure to a certain pressure position. Although the pressure meets the requirement of constant pressure, when water is not used, the frequency converter cannot stop completely and always maintains the lowest frequency speed.

This is because in a constant pressure water supply system, the minimum frequency of the frequency converter cannot be set to 0Hz, usually around 20Hz, which is determined by the combined flow and head of the water pump.

The solution is to set the sleep frequency. When the water pump is running at a frequency of not using water (such as 28Hz) for several minutes, the water pump will sleep. When the pressure drops to 0.2-0.4MP lower than the set pressure, the water pump will start. Another method is to set a timed water supply, which is divided into several time periods. Generally, constant pressure water supply controllers have the functions mentioned above

6. Hardware issues

After a problem occurs with the transformer (Hall) of the frequency converter, the correct current cannot be measured properly, and similar situations may also occur. In addition, aging of a measuring component on the motherboard can also occur, which is often encountered when repairing the frequency converter.

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