High-frequency isolation-type five-level inverter

Abstract

The invention provides a high-frequency isolation-type five-level inverter. The high-frequency isolation-type five-level inverter consists of an input direct-current power supply unit, voltage-dividing capacitors, a high-frequency isolation-type five-level conversion unit, a high-frequency isolation transformer, a cyclic wave converter, an output filter and an output alternating-current load, wherein on the basis of a full-bridge inverter, four capacitors are connected to two ends of an input direct-current voltage source in parallel to divide the voltage, so that five levels of Ui/2, Ui/4, 0, minus Ui/4, minus Ui/2 can be generated on the front end of the transformer, the five levels also can be sensed by a transformer side edge, the voltage stress on a switch tube can be reduced, and the waveform quality of the output voltage can be improved. The inverter has two levels of power transformation (direct current (DC)-high frequency alternating current (HFAC)-low frequency alternating current (LFAC)) and has the advantages of bi-directional power flow, low voltage stress on a switch device, good voltage spectrum characteristics on the front end of the output filter, small size of the output filter, low voltage stress on the switch tube and capability for electrically isolating the alternating-current load and the direct-current power supply in a high-frequency manner. The inverter can be applied to the application field with higher voltage and large power.

Description

technical field [0001] The invention belongs to the technical field of power electronic conversion, in particular to a high-frequency isolated five-level inverter. Background technique [0002] Direct-to-AC (DC-AC) conversion technology is a conversion technology that uses power semiconductor devices to convert DC power into constant-voltage and constant-frequency AC power, referred to as inverter technology. It is widely used in national defense, industrial and mining enterprises, scientific research institutes, university laboratories and daily life. With the development and application of new energy technology, the application of inverter technology in new energy is also increasing. [0003] Conventional inverter technology usually adds a first-class power frequency transformer between the inverter and the output to adjust the voltage ratio and serve as electrical isolation, but the power frequency transformer has the characteristics of large volume, audio noise, poor dy...

AI Technical Summary

Problems solved by technology

However, the diode-clamped and capacitor-clamped multi-level multi-point flat inverter technologies have defects such as single topology and no electrical isolation; the cascaded multi-level inverter technology with independent DC power supply has complicated circuit topology on the input side. Low power factor, low conversion efficiency, low power density and other defects

[0005] Most of the high-frequency isolation type multi-level topologies currently studied are concentrated in the unidirectional Buck-type high-frequency link inverter with a DC link in the middle, but a multi-level topology is added to the high-frequency electrical isolation DC / DC converter. The level technology reduces the voltage stress of the switch tube in the high-frequency electrical isolation DC / DC converter, but does not really realize multi-level at the front end of the output filter inductor, nor does it reduce the voltage stress of the switch tube of the inverter bridge , the value of the output filter inductor and capacitor has not been reduced

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