Neutral-point voltage control system and method for parameter on-line tuning

Abstract

The invention discloses a neutral-point voltage control system for parameter on-line tuning and a neutral-point voltage control method for parameter on-line tuning. The neutral-point voltage control system comprises a three-level inverter and a digital processing control module, wherein the digital processing control module comprises a sampling unit, a digital phase-locked loop unit, an output loop-closed control unit, a PI parameter online tuning unit, a neutral-point voltage PI control unit and an SVPWM (Space Vector Pulse Width Modulation) vector control unit; the output end of the SVPWM vector control unit is connected with each phase bridge arm of the three-level inverter through a driving circuit. The direct-current bias of the neutral-point voltage and the neutral-point voltage fluctuation can be restrained by the system and the method, so that the neutral-point voltage balance control can be realized.

Description

technical field [0001] The invention belongs to the field of control technology in power electronic conversion technology, in particular to a midpoint voltage control system and method for parameter online setting. Background technique [0002] With the rapid development of power electronic devices, high-voltage and high-power power electronic devices and AC speed control systems have been widely used in steelmaking and rolling industrial systems, electrochemical industrial systems, railway ship power systems and other fields. These power electronic devices have the characteristics of high control requirements, high power, high voltage level, and complex systems. Two-level inverters have many limitations such as high switching loss, high electromagnetic interference, and high voltage stress on the switch tubes, making it difficult for two-level inverters to meet these applications. Compared with the two-level inverter, the multi-level inverter has more output levels, and th...

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Problems solved by technology

For example: Literature 1 (Gong Bo, Cheng Shanmei, Qin Yi. Carrier-based three-level neutral point voltage balance control strategy [J]. Journal of Electrotechnical Society, 2013,28(6):172-177.) and patent 1( Cheng Shanmei, Gong Bo, Ning Bowen, Liu Jiang. A mid-point voltage control method for NPC type three-level inverter based on carrier amplitude shift: China, CN201210140269.0.2012-09-19.) A carrier-based The variable-amplitude SPWM control scheme eliminates the DC offset of the midpoint voltage by sampling the midpoint voltage to change the carrier amplitude in real time. However, the object of this method is the average value of the unbalanced component of the midpoint voltage in a power frequency cycle. The fluctuation of the midpoint voltage has no control effect

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