Method for suppressing fluctuation of bus voltage of electrolytic capacitor-free frequency converter based on neural network

Abstract

The invention discloses a method for suppressing the fluctuation of a bus voltage of an electrolytic capacitor-free frequency converter based on a neural network. The method comprises the following steps: firstly, a q-axis current expression is solved according to a power balance equation; a d-axis current control strategy is formulated according to a relationship that a voltage of a motor cannot be higher than a voltage which can be provided by an inverter; secondly, segmented logic is used, and a dynamic reference speed is given according to whether the bus voltage exceeds a threshold value or not; and finally, the BP neural network is built, the value of the fluctuation of the bus voltage serves as a performance index, dynamic reference speeds given by the segmented logic under different threshold values are subjected to data optimization, the neural network is trained to output the optimal dynamic reference speed, and the fluctuation of the bus voltage is suppressed. On the basis of a traditional electrolytic capacitor-free frequency converter, the output power is regulated in real time through the dynamic reference speed, so that the fluctuation of the bus voltage is suppressed; a dynamic reference speed generating method and a motor control method are relatively independent; and the method has the advantages of being high in universality, transplantable, constant in topological structure and high in reliability.

Description

technical field [0001] The invention belongs to the technical field of bus voltage fluctuation suppression of frequency converters without electrolytic capacitors, and in particular relates to a neural network-based method for suppressing bus voltage fluctuations of frequency converters without electrolytic capacitors. Background technique [0002] Frequency conversion technology has been widely used in the national economy due to its small starting current and convenient speed regulation. In traditional inverters, large-capacity electrolytic capacitors are connected in parallel on the bus to ensure the stability of the DC bus voltage. However, large-capacity electrolytic capacitors are large in size, short in life, and will reduce the power factor of the grid side. It has become a lightweight integrated inverter. a major obstacle. The frequency converter without electrolytic capacitor has the advantages of long life, high power density and high power factor, so the researc...

AI Technical Summary

Problems solved by technology

The topology improvement method is poor in economy and reliability because of the addition of new switching devices; the effect of the instantaneous power balance method in the control method optimization is better, but because the bus electrolytic capacitor is greatly reduced, the bus voltage will inevitably fluctuate greatly , causing the bus capacitor current to be too large, which will not only cause damage to the capacitor, but also affect the control effect of the motor

Images