Variable-frequency and variable-voltage multi-level high-power voltage source

Abstract

The invention relates to a variable-frequency and variable-voltage multi-level high-power voltage source. The variable-frequency and variable-voltage multi-level high-power voltage source comprises a first PWM (Pulse Width Modulation) inverter, a second PWM inverter, a first direct-current power supply and a second direct-current power supply, wherein the input ends of the first and second PWM inverters are connected with the output ends of the first and second direct-current power supply respectively; the output ends of the first and second PWM inverters are connected with the head and tail ends of a primary winding of a transformer after passing through a three-phase filter respectively. The voltage of the voltage source can be controlled flexibly, a large voltage vector can be generated through a single set of inverter, and low voltage is generated by controlling an included angle between two voltage vectors till the voltage is zero, thereby realizing high voltage accuracy and low harmonic waves during low-voltage output of the voltage source. When two sets of inverters are consistent in frequency, variable-frequency voltage can be output by controlling the frequency; when the two sets of inverters are inconsistent in frequency, mixed-frequency voltage output can be generated.

Description

technical field [0001] The invention relates to a high-power voltage source, in particular to an improvement of the topological structure of a variable-frequency variable-voltage high-power voltage source. Background technique [0002] The inverter voltage source of three-phase variable frequency variable voltage has been widely used, and most of them are realized by a single set of inverters. output. [0003] The simplest solution for inverter power supply to realize three-phase AC output is to directly use a three-phase full-bridge inverter to realize three-phase AC output, and use the three-phase output of the three-phase PWM inverter as the three phases A, B, and C respectively. This topology technology is relatively mature, and the control is simple and reliable. However, for lower voltage or zero voltage output, because of the settings of the controllable semiconductor device (such as IGBT) dead zone and minimum turn-on and turn-off time in the inverter, the low-volta...

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Problems solved by technology

[0003] The easiest way to achieve three-phase AC output is to use a three-phase full-bridge inverter directly to achieve three-phase AC output, and use a three-phase PWM inverter The three-phase output of the inverter is used as the three phases of A, B, and C respectively. This topology technology is relatively mature, and the control is simple and reliable. , the minimum on-off and off-time settings, the voltage accuracy is poor and the harmonics are large at low voltage output

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