Inverter overvoltage fault processing method - Database & Sql Blog Articles

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The commonly used low-voltage inverter belongs to the AC-DC-AC inverter, and the three-phase power source receives the DC power through the rectifier, and supplies power to the inverter through the DC bus. The bus voltage should be approximately equal to 1.35 times the incoming line voltage under normal conditions.
In order to protect the inverter, when the bus voltage is too high, the inverter will report an overvoltage fault and block the pulse output of the inverter. This is an important and necessary method to protect the drive components from damage. This fault cannot be blocked.
There is a bus voltage check mechanism inside the inverter. When the bus voltage measurement value is higher than a certain threshold, the inverter will report an overvoltage fault.
There are many reasons for DC bus overvoltage, which should be analyzed according to actual conditions. If you find the right source, and then the right medicine, you can generally solve it.
1 First is the effect from the incoming line voltage.
If the quality of the power grid is not good and there is an instantaneous high voltage, it will inevitably cause the bus voltage to be too high. Occasionally, the instantaneous voltage spikes are difficult to capture, which makes it difficult to diagnose faults. If an oscilloscope or power quality analyzer is used to capture the flicker of the incoming line voltage and confirm that there is a voltage spike in the grid, a voltage spike absorber can be installed at the incoming end of the inverter to protect the inverter.
When thundering, it may also have a transient effect on the grid voltage, and may also cause overvoltage faults in the inverter. However, thunder is also an accidental event that will not always bother the operation of the inverter. However, for safety reasons, the factory should have lightning protection measures.
2 followed by the effect from the output, ie the inverter side.
During motor braking (ie, deceleration), the kinetic energy of the motor and load is converted into electrical energy, which is in the state of power generation, and the generated electricity accumulates on the DC bus, causing the bus voltage to become higher and higher. If the mechanical system of the motor has large inertia and the braking time is short, the braking power is large. The generated electric energy is continuously accumulated in the inverter, and it is too late to release, which easily causes the DC bus overvoltage. In response to this inevitable situation, the frequency converter has been designed with a number of features to deal with. The general treatment methods are:
Extend the braking time within the scope of the process requirements.
During the stop, enable the Vdmax controller to automatically extend the braking time using the appropriate brake unit and braking resistor (this is costly)
Rectifiers operating in four quadrants, such as rectifiers based on AFE, F3E principles, if using PID technology controllers, pay attention to reduce system response, reduce P plus I, extend filter time
3 Finally is the hardware problem.
If the voltage detection mechanism inside the inverter is not working properly, or if there is a problem with the CPU processing mechanism, these are not solved by setting parameters, and need to be repaired. If it is an external mechanical problem, such as installation eccentricity, this is also to be avoided.