NPC (neutral point clamped) three-level inverter vector control system based on novel flux observer

Abstract

An NPC (neutral point clamped) three-level inverter vector control system based on a novel flux observer provides a simplified SVPWM (space vector pulse width modulation) algorithm. A three-level space vector is decomposed into a two-level space vector; a reference voltage vector is translated; a two-level SVPWM algorithm is used to obtain action time of each basic vector and to choose a right switching status; and the three-level inverter vector control calculation is reduced. Meanwhile, in the invention, the novel flux observer is employed to calculate the rotor flux, so that a current model and a voltage model are used respectively at a low speed and at a high speed; and when a rotation speed is between the low speed and the high speed, an invented hybrid flux observer is used to calculate the rotor flux.

Description

Technical field [0001] The invention belongs to the field of high-voltage and high-power AC variable frequency speed regulation, and relates to a simplified SVPWM algorithm based on a diode clamped (NPC) three-level inverter, vector control of an induction motor and a novel hybrid flux observer. Background technique [0002] Since the NPC three-level inverter topology was proposed, after years of development and research, it has now been widely used in high-voltage and high-power inverter occasions. The characteristic of this type of topology is that the voltage value of each switching device is equivalent to half of the original DC voltage, so that low-voltage high-speed switching devices (IGBT, etc.) can be used to replace high-voltage low-speed switching devices (GTO, etc.). Its , The common mode interference is relatively small, which greatly reduces the electromagnetic interference and the peak voltage on the motor winding. In AC speed regulation, the insulation performanc...

AI Technical Summary

Problems solved by technology

[0003] The SVPWM modulation algorithm is widely used in the NPC three-level inverter control system because of its high voltage utilization rate, low harmonic content of the output waveform, and easy digital realization. chain estimation accuracy

In the vector control system, the observation of the rotor flux linkage is a very important link in the vector speed control system of the induction motor. Its accuracy has a direct impact on the stability and accuracy of the system. The traditional flux linkage observation has a direct current offset, resulting in certain magnitude and phase angle errors

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