The modified sine wave inverter outputs a square wave alternating current of poor quality, and its positive maximum value to negative maximum value are generated at the same time, which causes severe instability effects on the load and the inverter itself. At the same time, its load capacity is poor, only 40-60% of the rated load, can not carry inductive load. If the load is too large, the third harmonic component contained in the square wave current will increase the capacitive current flowing into the load, and in severe cases will damage the load filter capacitor of the load.
In response to the above shortcomings, inverters with modified sine waves (or improved sine waves, quasi-sine waves, analog sine waves, etc.) have appeared in recent years, and the output waveform has a time from the positive maximum value to the negative maximum value. Interval, the effect of use has been improved, but the waveform of the modified sine wave is still composed of polylines, still belongs to the square wave category, the continuity is not good, and there is a dead zone (the waveform is as shown below).
Modified sine wave inverters generally use non-isolated coupling circuits, while pure sine wave inverters use isolated coupling circuits. The price is also a lot different. Correcting the sine wave switching inverter power supply not only saves the bulky power frequency transformer, but also greatly improves the efficiency of the inverter by 90%.
The modified sine wave switching inverter power supply uses PWM pulse width modulation to generate the modified wave output. In the inverter process, the power loss of the system is greatly reduced due to the use of dedicated intelligent circuits and high-power FETs. And the soft start function is added to effectively ensure the reliability of the inverter. If the quality requirements for power consumption are not very high, and it can meet the needs of most electrical equipment, it still has 20% harmonic distortion, which will cause problems when running precision equipment, and will also cause high frequency to communication equipment. interference.