主电路功率开关元件的自关断化、模块化、集成化、智能化，开关频率不断提高

The main circuit power switching elements are self-off, modular, integrated, and intelligent, and the switching frequency is continuously increased, and the switching loss is further reduced. The power switching devices commonly used in low-voltage small-capacity inverters are: power M OSFET, IG-BT (insulated gate bipolar transistor) and IPM (intelligent power module). The medium-voltage large-capacity inverter adopts: GTO (gate turn-off thyristor), IGCT (integrated gate commutated thyristor), SGCT (symmetrical gate commutated thyristor), IEGT (injection enhanced gate transistor) and high-voltage IGBT. The topology structure of the main circuit of the inverter: the grid-side converter of the inverter often uses a 6-pulse converter for low-voltage and small-capacity, and a multiplexed converter with more than 12 pulses for medium-voltage and large-capacity. Load-side converters often use two-level bridge inverters for low-voltage and small-capacity, and multi-level inverters for medium-voltage and large-capacity. It is worth noting that for the four-quadrant operation of the drive, in order to realize the regenerative energy of the inverter to feed back to the grid and save energy, the grid-side converter should be an inverter, and there are double PWM inverters with power flowing in both directions. Appropriate control of the grid-side converter can make the input current close to the sine wave, and make the power factor of the system close to 1, reducing the pollution to the power grid. At present, low and medium voltage inverters have such products. The use of public DC bus technology makes the energy of multiple (or multi-axis) transmission systems better used, improves the overall operating efficiency of the system, and can reduce the price of the inverter itself. The public DC bus can also have regenerative and non-regenerative types. Explore the use of resonant DC loop technology to make the power switch of the inverter work in the soft switching state, the device loss is greatly reduced, the switching frequency can be further increased, the E-MI problems caused by voltage and current spikes are suppressed, and the buffer circuit can be eliminated.

The main circuit power switch ingress, modularizes, integrates and is intelligent, the switching frequency is constantly increasing, and the switching loss is further reduced. The power switching devices commonly used in low-voltage small-capacity inverters are: power M OSFET, IG-BT (insulated gate double extreme transistor) and IPM (intelligent power module). Medium-voltage high-capacity inverters are used in: GTO (gate pole can be shut down, IGCT (integrated gate switching stratosphine tube), SGCT (symmetric gate switching stratosphine tube), IEGT (injection enhanced gate transistor) and high-pressure IGBT. The topological aspect of the main circuit of the inverter: the network side converter of the inverter often uses 6 pulse converter for low-voltage small capacity, while the medium-voltage high-capacity uses multiple converters of 12 pulses or more. The load side converter often uses a two-level bridge inverter for low-voltage small capacity, while a multi-level inverter for medium pressure high capacity. It is worth noting that for the four-quadrant running transmission, in order to achieve the regeneration of the inverter energy to the grid feedback and energy saving, the network side converter should be reversible converter, the emergence of power can flow in both directions of the dual PWM inverter, the network side converter to properly control the input current close to the sine wave, and make the system's power factor close to 1, reduce the public hazard to the grid. At present, low, medium voltage inverters have such products. The adoption of common DC bus technology makes the use of multiple (or multi-axis) drivesystems better, improving the overall operating efficiency of the system, and reducing the price of the drive itself. Common DC busses can also be regenerative and non-regenerative. It is explored that the power switch of the inverter is used to make the power switch of the inverter operate in the soft switch state, the device loss is greatly reduced, the switching frequency can be further improved, the E-MI problem caused by voltage and current spike is suppressed, and the buffer circuit can be cancelled.

The main circuit power switch elements are self closing, modularized, integrated and intelligent, the switching frequency is continuously increased, and the switching loss is further reduced. The power switch devices commonly used in low-voltage small capacity inverter are: power MOSFET, ig-bt (insulated gate double extreme transistor) and IPM (intelligent power module). The medium voltage large capacity frequency converter adopts GTO (gate can turn off thyristor), IGCT (integrated gate converter thyristor), sgct (symmetrical gate converter thyristor), IEGT (injection enhanced gate transistor) and high voltage IGBT. The main circuit topology of the converter: the grid side converter of the converter usually uses 6-pulse converter for low voltage and small capacity, and uses multiple 12 pulse converter for medium voltage and large capacity. The load side converter usually uses two-level bridge inverter for low voltage and small capacity, and multi-level inverter for medium voltage and large capacity. It is worth noting that for the four quadrant drive, in order to realize the regenerative energy of the frequency converter to feed back to the grid and save energy, the grid side converter should be a reversible converter, and a dual PWM frequency converter with bidirectional power flow appears. Proper control of the grid side converter can make the input current close to the sine wave, and make the power factor of the system close to 1, so as to reduce the pollution to the grid. At present, low and medium voltage inverters have such products. The adoption of common DC bus technology makes the energy of multiple (or multi axis) drive systems better utilized, improves the overall operation efficiency of the system, and reduces the price of the frequency converter itself. The common DC bus can also be regenerative or non regenerative. The resonant DC loop technology is explored to make the power switch of the converter work in soft switch state, the device loss is greatly reduced, the switching frequency can be further improved, the e-mi problem caused by voltage and current spikes can be suppressed, and the buffer circuit can be cancelled.<br>