How to understand an inverter

1. Rated output voltage

Within the predetermined fluctuation range of the allowed DC voltage input, the rated voltage representing the inverter can be output. The stable accuracy of the output voltage rating is generally specified as follows:

(1) During quasi-steady state operation, the voltage fluctuation range should be limited, such that the deviation does not exceed ±3% or ±5% of the rated value.

(2) Under sudden load changes (rated load 0%-50%-100%) or other interference factors affecting dynamic conditions, the output voltage deviation should not exceed ±8% or ±10% of the rated value.

2. Output voltage is unbalanced

Under normal operating conditions, the three-phase unbalanced voltage (ratio of negative sequence component and positive sequence component) output by the inverter should not exceed the specified value, usually expressed as a percentage, such as 5% or 8%.

Power frequency inverter

3. Output voltage

Waveform Distortion When the inverter output voltage is a sine wave, an allowable large waveform distortion (or harmonic content) should be provided. Typically, it is represented by total output voltage waveform distortion. Its value should not exceed 5% (single phase output to 10%).

4. Rated output frequency

The frequency of the AC voltage output by the inverter should be relatively stable, usually 50Hz. Under normal operating conditions, the deviation should be within ±1%.

5. Load power factor

Characterizes the capacity of the inductive load or capacitive load of the inverter. Under sine wave conditions, the load power factor is 0.7 to 0.9 (lag), with a nominal value of 0.9.

6. Rated output current (or rated output capacity)

Indicates the rated load power factor and rated output current of the inverter within the specified range. Rated output capacity of some frequency converters. The unit is VA or kVA. When the output power factor is 1 (that is, purely resistive load), the rated capacity of the inverter is the product of the rated output voltage and the rated output current.

Inverter

7. Rated output efficiency

Inverter efficiency is the ratio of output power to input power under specified operating conditions, expressed as a percentage. The inverter efficiency is the full load efficiency under the rated output capacity, and 10% of the rated output capacity efficiency is the low load efficiency.

8. Protect

(1) Overvoltage protection: Frequency converters without voltage stabilization measures should have output overvoltage protection measures to ensure that the load is not damaged by output overvoltage.

(2) Overcurrent protection: The overload current protection of the frequency converter should ensure that the load short-circuit current or exceeds the allowable value will act in time to avoid damage by surge current.

9. Launch Features

It describes load startup performance and dynamic working capabilities. The inverter should ensure reliable starting under rated load.

Inverter

10. Noise

Components of power electronic equipment such as transformers, filter inductors, magnetic switches, fans, etc. all generate noise. When the frequency converter is working normally, the noise should not exceed 80dB, and the noise of the small inverter should not exceed 65 dB.