Power Inverter buy points

How to choose the correct ups power inverter mainly pay attention to the following points .
1 , the rated output voltage: within a predetermined fluctuation range of the input DC voltage is allowed , it means that the rated voltage of the inverter should be output . The stability of rated output voltage accuracy is generally defined as follows : In steady-state operation , the voltage fluctuation range should be a limit , such as the deviation does not exceed the rating of ± 3% or ± 5%. Under load mutations or other interfering factors affecting the dynamics of the output voltage deviation should not exceed the rating of ± 8% or ± 10%.
2 , the output voltage imbalance : Under normal operating conditions, the inverter output phase voltage unbalance ( reverse component of the ratio of positive sequence component ) should not exceed a specified value , usually expressed in% as 5 % or 8 %.
3 , the output voltage waveform distortion : When the  220 volt power inverters   output voltage is sinusoidal , shall specify the maximum allowable waveform distortion ( or harmonic content ) . Usually to a total distortion of the output voltage waveform that its value should not exceed 5% ( 10% single phase output enable ) .
4 , rated output frequency of the inverter output AC voltage frequency should be a relatively stable value , usually frequency 50Hz. Under normal operating conditions the deviation should be within ± 1 %.
5 , the load power factor : the ability to characterize the capacitive load inverter with inductive load or . In the sine condition, the load power factor of 0.7 to 0.9 ( hysteresis ) , the rating is 0.9 .
6, rated output current : Indicates the inverter within the specified range of the rated output power factor of the load current . Some inverter products given is rated output capacity , the unit in VA or KVA said . The rated capacity of the inverter when the output power factor of 1 ( ie, purely resistive load ) , the rated output voltage of the rated output current of the product.
7 , rated output efficiency: The efficiency of the AC power inverters inverter under specified operating conditions , the output power to input power ratio , in%. Inverter efficiency at rated output capacity for full load efficiency of 10% at rated output capacity efficiency at low load efficiency.
8 , Protection: over-voltage protection : No voltage stabilization measures for the inverter output over-voltage protection measures due to the negative output cut from overvoltage damage.
Overcurrent protection : inverter over-current protection , should be able to ensure that a short circuit in the load current exceeds the allowable value or action from time to time , so from inrush current damage.
9 , starting characteristics : characterizing the performance of the inverter starting with a load capacity and dynamic work. The inverter should ensure reliable starting at rated load .
10 , the noise : the transformer power electronic device , the filter inductor , electromagnetic switches and other components are the fan noise is generated . Normal operation of the inverter , the noise should not exceed 80dB, small inverter noise should not exceed 65dB.

The working principle of the inverter

1 . Full-controlled inverter works: Figure 3 shows , for the full-bridge inverter main circuit commonly used single-phase output figure, the AC components using
the IGBT Q11, Q12, Q13, Q14. Controlled by the PWM pulse width modulation IGBT tube turned on or off .
   When the  4000 watt power inverter  circuit connected to a DC power source , first Q11, Q14 is turned on , Q1, Q13 is turned off, the current from the positive output of theDC
power supply , via Q11, L or sense transformer primary winding 1-2, back to Q14
to the negative power supply . When Q11, Q14 after the deadline , Q12, Q13 is
turned on , current flows from the positive power supply through Q13, electrical
transformer primary winding 2-1 am Q12 back negative power . In this case, the
transformer primary winding , has formed an alternating positive and negative
square wave , the use of high frequency PWM control , two pairs of IGBT tube
alternately repeated , generating an AC voltage on the transformer . Since LC AC
filter effect, so that the output AC voltage sine wave form .
   When Q11, Q14 off when , in order to release the stored energy in the IGBT
diode in parallel at D11, D12, so that energy back to the DC power supply to go.Th2 is triggered according conduction, because reverse biased anode Th2 , Th1
off, return the blocking state . Thus , Th1 and Th2 commutation , and then charge the capacitor C and reverse polarity . So turn triggered thyristors ,
alternating current flows transformer primary , the secondary of the transformer
to get the AC .
   In the circuit, the inductance L can be limited for the discharge current of
the capacitor C , to extend the discharge time to ensure that the circuit is
greater than the turn-off time of the  220 volt power inverters  turn-off time without a large
capacity capacitor . D1 and D2 are two feedback diode , inductor L can be the
energy release , it will be returned to the remaining energy supply , completethe feedback energy.

Analysis of car inverter

The inverter according to different sources of power, divided into coal power inverter, solar 2500 watt power inverter, power inverter, power inverter. According to different purposes, divided into independent control of the inverter, grid connected inverter. The efficiency problem of the current domestic market inverter. The 8000 watt power inverters in the work itself also consumes a part of the power, therefore, its input power than its output power.