Learn about the types and features of inverters in one article

As power conversion equipment, inverters play an important role in modern power systems. According to different classification criteria, inverters can be divided into various types, each type has its specific application scenarios and characteristics. The following is a detailed categorization and expanded description of inverter types:

Classification by Input Source:

• Voltage Source Inverter: Voltage source inverters usually input a constant DC voltage source, such as a battery pack or a DC power source. Since the DC power source has zero impedance, it is considered as a rigid voltage source. Voltage source inverters are widely used in applications that require stable voltage output, such as frequency converters and UPS power supplies.
• Current Source Inverter: Unlike voltage source inverter, the input of current source inverter is a constant DC current source. Its DC side is a high impedance current source, which provides a rigid current that is almost unaffected by load changes. Current source inverters are commonly used in industrial processes that require a stable current output, such as electroplating and electrolysis.

Categorized by output phase:

• Single-phase inverter: A single-phase inverter converts DC to single-phase AC with only one phase of output voltage and current. It is usually used in homes, small commercial premises and low load working condition applications such as household appliances, power tools etc. The nominal frequency of a single-phase inverter is usually 50Hz or 60Hz.
• Three-phase inverters: Three-phase inverters convert DC power to three-phase AC power for industrial equipment and power systems that require three-phase power. Three-phase power supplies provide three intersecting and evenly separated alternating current (AC) circuits with higher power supply capability and stability. Three-phase inverter is commonly used in large motors, generator sets and power systems and other fields.

Categorized by working principle and structure:

• Bridge inverter: The bridge inverter converts DC into AC by controlling the on-off switching tube on the bridge arm. Half-bridge inverter is suitable for small and medium power occasions, simple structure, low cost; full-bridge inverter is suitable for high-power occasions, with higher output power and stability; three-phase bridge inverter is used in the need for three-phase AC output occasions.
• Shunt inverter: Shunt inverter consists of multiple inverters connected in parallel to share the load. This type of inverter has higher output power and better redundancy, and is suitable for applications requiring high reliability and stability. Shunt inverters are commonly used in power systems, data centers and critical facilities.
• Series inverters: Series inverters are used where high voltage output is required, such as in high voltage DC transmission systems. It realizes high-voltage output by connecting multiple inverter units in series to meet the needs of specific application scenarios.

Categorized by output waveform:

• Square wave inverter: The output waveform of square wave inverter is square wave, which has simple structure and lower cost. However, due to its waveform contains more high harmonics, which may adversely affect the load. Therefore, square wave inverters are usually used in applications where waveform requirements are not high.
• Stepped wave inverter (or quasi-sinusoidal inverter): The output waveform of a stepped wave inverter is a waveform with a stepped square waveform, which is close to a sinusoidal waveform. It has lower harmonic content and better load adaptability, and is suitable for occasions with higher requirements on waveforms.
• Sine inverter: The output waveform of sine inverter is almost sinusoidal with smooth waveform and low harmonic content. It is suitable for occasions with very high requirements on waveform, such as medical equipment, precision instruments, etc.

Categorized by output AC frequency:

• Industrial frequency inverter: The output AC frequency of industrial frequency inverter is 50Hz or 60Hz, which is the same as the grid frequency. It is suitable for the occasions which need to synchronize with the AC power grid, such as household power, commercial power, etc.
• Medium Frequency Inverter: The frequency of the output AC of the medium frequency inverter is between several hundred and several thousand hertz. It is commonly used in high frequency induction heating, ultrasonic treatment and other industrial fields.
• High-frequency inverter: The frequency of output AC power of high-frequency inverter reaches above tens of kilohertz. It is suitable for occasions requiring high-frequency output, such as wireless communications, radar systems, etc.

Classified by commutation technology:

• Line commutation inverter: The line voltage of the AC circuit of the line commutation inverter can be obtained through the device. When the current in the SCR experiences the zero characteristic, the device is turned off and commutation is realized. This type of inverter is commonly used in some specific power electronic devices.
• Forced commutation inverter: The forced commutation inverter achieves commutation by forcing the control and allows commutation operation even if the power supply will not experience a zero characteristic. It is suitable for the need to accurately control the moment of commutation occasions, such as high-performance power electronic equipment.

Categorized by operation mode:

• Off-grid inverter: Off-grid inverter can supply power to the load by itself without being affected by the power grid or other power sources. It is suitable for remote areas, occasions without grid coverage or used as a backup power source.
• Grid-tie inverter: A grid-tie inverter can provide AC power to AC loads from storage devices and additional power to the grid. It is commonly used in grid-connected renewable energy systems such as solar power systems and wind power systems.
• Twin Peak Inverter: The Twin Peak Inverter works as both a grid-connected inverter and an off-grid inverter. It has a flexible choice of operating modes and is suitable for occasions where both grid-connected and off-grid requirements need to be met.

The above is a detailed categorization and expanded description of the inverter types. By understanding the characteristics and application scenarios of different types of inverters, users can choose the right type of inverter according to their specific needs to meet different power conversion requirements.