1. First, what does the “frequency” mean?

2. What is the difference of DC-AC conversion between low frequency and high frequency inverter?

Second, high voltage DC to AC
Finally, 220V low frequency AC power is obtained for the load through the low frequency inverter circuit.

Since the high-frequency inverter uses small-sized, lightweight high-frequency magnetic core materials, the power density of the circuit is greatly improved, so that the no-load loss of the inverter power supply is small, and the inverter efficiency is improved. Usually, the peak conversion efficiency of high-frequency inverters used in small and medium-sized PVS can reach more than 90%.

Picture Above. Typical high frequency inverter with small transformer

LOW FREQUENCY INVERTER
The low frequency inverter first inverts the DC power into a low frequency low-voltage AC power, and then boosts it into 220V, 50Hz AC power for the load through a low frequency transformer. Its advantage is that the structure is simple, and various protection functions can be realized at a lower voltage. Because there is a low 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 high-order harmonic components in the waveform. 

However, low frequency transformers also have the problems of being bulky and expensive, and their efficiency is relatively low. The rated load efficiency of the small low frequency inverter manufactured according to the current level generally is between 80%-90%. At the same time, the iron loss of the low frequency transformer is basically unchanged when the low frequency transformer operates under full load and light load, so it can be operated under light load. The no-load power consumption is high, and the efficiency is low.

Picture Above. Typical low frequency inverter with heavy duty transformer.

EFFICIENCY
High-frequency inverters are generally more efficient at converting power when maintaining a constant load for lighter loads, which is important when you’re relying on battery power in remote locations. However, they may struggle with high surge currents or heavy loads. High frequency inverters at no-load power consumption uses less power from the battery compared to low frequency inverters. The rated power of high-frequency inverters matches the wattage it delivers whereas low-frequency inverters don’t.

Example:
High frequency 3000W inverter would be equivalent to 3000W
Low frequency 3000VA inverter would be equivalent to 2400W

Low-frequency inverters are known for their robustness and ability to handle high surge currents, making them suitable for powering heavy-duty appliances or equipment with high starting currents, such as motors and compressors.

WEIGHT
High frequency inverters can deliver the same power at higher frequency with a much smaller and lighter transformer, as a result, the high frequency inverter is lighter than low frequency inverters.

Low-frequency inverters are generally heavier than high-frequency inverters, mainly due to their larger and heavier transformers.

APPLICATIONS
High frequency inverters are better suited for off-grid systems with lighter loads and more stable operating conditions, such as residential light-load household appliances or small-scale off-grid installations, RV’s, Mobile homes and caravans.

Low frequency inverters are more suitable for off-grid systems where heavy loads and extreme conditions are expected, such as in industrial applications or in remote locations with harsh environments.