Electric energy conversion device and method for determining optimal parallel connection number of direct-current circuits of electric energy conversion device

Abstract

The invention discloses an electric energy conversion device and a method for determining the optimal parallel connection number of direct-current circuits of the electric energy conversion device. The electric energy conversion device comprises a power supply module, N interleaving direct-current conversion circuits and an MPPT core control module, wherein the N interleaving direct-current conversion circuits are connected with the power supply module, and the MPPT core control module is connected with a control end of the N interleaving direct-current conversion circuits. The N interleaving direct-current conversion circuits comprise a voltage conversion circuit and an input filter capacitor, wherein the voltage conversion circuit serves as a voltage reduction unit or a boost unit or a boost / voltage reduction unit. The method for determining the optimal parallel connection number of the direct-current circuits of the electric energy conversion device comprises the steps that the range of the duty ratio of the direct-current conversion circuits is calculated, a graph of the relation between the duty ratio and electric current normalization ripple amplitudes is drawn, and finally the optimal parallel connection number is obtained according to the graph and the range of the duty ratio. According to the electric energy conversion device and the method for determining the optimal parallel connection number of the direct-current circuits of the electric energy conversion device, power supply reliability is improved, the maximum power output of a whole system is ensured, efficiency of the system is improved, the system can have the optimal output current ripple characteristic, the capacity of a filter is reduced, and the output power of the system is improved.

Description

technical field [0001] The invention belongs to the field of new energy devices, relates to an electric energy conversion device, and also relates to a method for determining the optimal number of parallel circuits of a DC conversion circuit of the electric energy conversion device. Background technique [0002] In solar and wind energy and other new energy grid-connected applications, there is a problem of maximum power point tracking. The ripple voltage at the DC terminal will affect the harmonic current of the grid-connected inverter, the efficiency of the inverter and the filter capacitor. The size, reducing the ripple size of the DC side of the inverter, and reducing the size of the filter capacitor are of great significance to the grid-connected inverter. [0003] On the other hand, there is an energy storage battery in the new energy off-grid system, which needs to be charged. The new energy charging device refers to the device that the new energy power supply module ...

AI Technical Summary

Problems solved by technology

Based on the above requirements, two-way interleaved parallel circuit structure has been seen on the market, and the relationship between its working duty cycle and the normalized current amplitude K is as follows: figure 2 As shown (where the current normalized ripple amplitude K is defined as the ratio of the output current ripple amplitude to the output ripple amplitude of the single-channel DC conversion circuit), the current ripple and the device volume have been improved to a certain extent, but The two-way parallel connection still fails to completely improve the ripple problem, and the ripple amplitude is still relatively large, which is about 2 / 3 times the ripple amplitude of the single-way conversion circuit

Moreover, the design of the existing parallel interleaved circuit structure is not designed for the specific new energy power supply module voltage and battery voltage, and no guiding design method and design steps are given.

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