UPS inverter power stage one pair amplifier transistor is damaged

UPS inverter power stage one pair amplifier transistor is damaged, replace the same type of transistor after running for some time because they burn too much current, caused by excessive current reasons:
- Overcurrent failure. When the inverter output overcurrent, the overcurrent protection circuit does not work;
- Pulse Width Modulation (PWM) component failure, the two complementary output waveform asymmetry, a long lead-time, on-time and short the other, so that the work of unbalanced arms, even the arms are turned on simultaneously, resulting in two tube is damaged;
- Solar panel inverter difference between the larger tube parameters, then even if the input waveform symmetry, the output will be asymmetrical, the waveform is output transformer, causing magnetic bias, ie the flux imbalance, leading to the accumulation of down transformer saturation current surge, burn computer ups power supply tube, and a burn, the other also will burn.
4, after UPS boot, no display on the panel, UPS does not work.
Failure Analysis: From Symptom judgment, the failure in the mains input, battery and mains detection portion and the battery voltage detection circuit:
- Check the mains input fuse is burned;
- If the mains input fuse is good, check the battery insurance burned, because some UPS when the battery voltage is less than the self-test, all of the output of the UPS and the display will be closed;
- If the battery insurance intact, check the mains detection circuit is working properly, if the mains detection circuit is not working properly and the UPS does not have no electricity start function, UPS also will shut down all output and display.
- If the city detection circuit is working properly, then check the battery voltage detection circuit is normal.

 

UPS string inverters

UPS string inverters
String inverters are now on the international market has become the most popular inverter. String inverters are based on each PV string (1kW-5kW) through an inverter, the DC side with a maximum peak pure sine wave online ups tracking based on a modular concept, in parallel with the AC-side and network
. Many large-scale photovoltaic power plants using string inverters. The advantage is the difference between the modules without strings and impact of shading, while reducing the optimal operating point of PV modules
In the case of the inverter mismatch, thereby increasing the generation capacity. Technically these advantages not only reduces system cost, but also increase the reliability of the system. Meanwhile, in the string between the introduction - the concept of "master-slave", so in the system in a single string of energy can not work a single inverter case, several groups of PV strings together, so that one or several working to produce more Solar panel inverter. The latest concept for several inverters with each other to form a "team" instead of "master - slave" concept, making the reliability of the system one step further.