What are the differences between high-frequency inverter and power frequency inverter?  

An inverter is a device that converts direct current (DC) to alternating current (AC) to meet the power demand of AC load.  According to the topology, the inverter can be divided into the high-frequency inverter and power frequency inverter.  
 
High-frequency inverter
 
High-frequency inverter first through high-frequency DC/DC conversion technology, low voltage DC inverter to high-frequency low voltage AC;  Then after the high-frequency transformer voltage boost, and then through the high-frequency rectifier filter circuit rectifier is usually more than 300V high voltage DC, and finally through the power frequency inverter circuit to get 220V ac power for load use.  
 
Because the high-frequency inverter uses small volume, lightweight high-frequency core material, which significantly improves the power density of the circuit, the no-load loss of the inverter power supply is slight, and the inverter efficiency is improved.  Typically, high-frequency inverters used in small and medium PVS have a peak conversion efficiency of more than 90%.  

 
Power frequency inverter
 
The power-frequency inverter firstly inverts the DC into power-frequency low-voltage AC and then boosts it into 220V and 50Hz AC for the load.  
 
Its advantages are simple structure and various protection functions that can be realized at a lower voltage.  Because there is a power-frequency transformer between the inverter power supply and the load, the inverter runs stably, and reliably, has strong overload capacity and impact resistance, and can suppress the high harmonic components in the waveform.  However, the power-frequency transformer also has the problem of heavy and high price, and its efficiency is relatively low.  
 
The rated load efficiency of the small power frequency inverter manufactured at the current level is generally not more than 90%, and the iron loss of the power frequency transformer is basically unchanged when it runs under full load and light load, so the no-load loss of the power frequency transformer under light load is large and the efficiency is low