What is Inverter power supply

What is Inverter power supply?

The power inverter (on-board power supply) is a convenient power converter that can convert DC12V DC power into AC220V AC power the same as the mains power for general electrical appliances.

An inverter can only be called as such if it is composed of an inverter device. It is directly different from a transformer, that is, it can realize DC input and then output AC. Its working principle is the same as that of a switching power supply, but the oscillation frequency is within a certain range. For example, if the frequency is 50HZ, the output is AC 50HZ. Inverter is a device that can change its frequency. 

How to choose the correct ups inverter should pay attention to the following points.

1. Rated output voltage: within the allowable fluctuation range of the specified input DC voltage, it represents the rated voltage value that the inverter should be able to output. The stability accuracy of the output rated voltage value is generally specified as follows: during steady state operation, the voltage fluctuation range shall be limited, for example, its deviation shall not exceed ± 3% or ± 5% of the rated value. Under the dynamic condition of sudden load change or other interference factors, the output voltage deviation shall not exceed ± 8% or ± 10% of the rated value.

2. Unbalance degree of output voltage: under normal working conditions, the three-phase voltage imbalance degree (ratio of reverse sequence component to positive sequence component) output by the inverter shall not exceed a specified value, generally expressed in%, such as 5% or 8%.

3. Waveform distortion of output voltage: when the inverter output voltage is sinusoidal, the maximum allowable waveform distortion (or harmonic content) shall be specified. Generally, it is expressed by the total waveform distortion of the output voltage, and its value should not exceed 5% (10% is allowed for single-phase output).

4. Rated output frequency The frequency of the inverter's output AC voltage should be a relatively stable value, usually 50Hz power frequency. Under normal working conditions, the deviation shall be within ± 1%.

5. Load power factor: it represents the capability of the inverter with inductive load or capacitive load. Under the sine wave condition, the load power factor is 0.7 ～ 0.9 (lagging), and the rated value is 0.9.

6. Rated output current: refers to the rated output current of the inverter within the specified load power factor range. Some inverter products provide rated output capacity, which is expressed in VA or KVA. The rated capacity of inverter is the product of rated output voltage and rated output current when the output power factor is 1 (i.e. pure resistive load).

7. Rated output efficiency: the efficiency of inverter is the ratio of output power to input power under specified working conditions, expressed in%. The efficiency of inverter at rated output capacity is full load efficiency, and the efficiency at 10% rated output capacity is low load efficiency.

8. Protection: over-voltage protection: for inverters without voltage stability measures, there should be output over-voltage protection measures to prevent negative cutoff from the damage of output over-voltage.

Overcurrent protection: The over-current protection of the inverter shall be able to ensure timely action in case of load short circuit or current exceeding the allowable value, so as to prevent it from being damaged by surge current.

9. Starting characteristics: it represents the starting ability of the inverter with load and the performance during dynamic operation. The inverter shall ensure reliable starting under rated load.

10. Noise: transformers, filter inductors, electromagnetic switches, fans and other components in power electronic equipment will generate noise. During normal operation of inverter, the noise shall not exceed 80dB, and the noise of small inverter shall not exceed 65dB.