CN103312147A

CN103312147A - Inverter common-mode interference suppression circuit

Info

Publication number: CN103312147A
Application number: CN2012100801937A
Authority: CN
Inventors: 张永
Original assignee: FENGZHI (SHANGHAI) NEW ENERGY TECHNOLOGY Co Ltd
Current assignee: FENGZHI (SHANGHAI) NEW ENERGY TECHNOLOGY Co Ltd
Priority date: 2012-03-17
Filing date: 2012-03-17
Publication date: 2013-09-18

Abstract

The invention relates to an inverter common-mode interference suppression circuit, which belongs to a circuit for suppressing the common-mode interference output between the direct current and alternating current sides of an inverter. The circuit can be widely applied to the inverter with high suppression requirements on common-mode current, such as transformer-free photovoltaic grid connected inverters. A realization method of the inverter common-mode interference suppression circuit is characterized in that two capacitors with the same capacity are connected in series between two electrodes of the alternating current output side, capacitors are connected between the direct current input end and the middle point of the capacitors, and in addition, a common-mode reactor is added in a proper position of the circuit. The inverter common-mode interference suppression circuit has the advantages that the suppression on the inverter circuit common-mode interference is realized at lower cost, the electromagnetic capacitive character of a system is improved, and in addition, the support is provided for realizing isolation-transformer-free inverters.

Description

The inverter common mode disturbances suppresses circuit

Technical field

The electric power unsteady flow field that the invention belongs to is a kind of circuit that suppresses common mode disturbances output between inverter direct current and the AC, can be widely used in common mode current is suppressed in the demanding inverter, such as the transless photovoltaic merging inverter etc.

Background technology

The inverter that many application scenarios are arranged, photovoltaic combining inverter for example, used adopts the isolated form inverter with transformer, yet, because the existence of isolating transformer has reduced the efficient of system, also increased cost simultaneously.In order to overcome the deficiency of above-mentioned transformer isolation type inverter, present trend is to adopt transformerless non-isolation type inverter.The outstanding advantage of transless inverter is that efficient is high, and holistic cost is low.But transformerless inverter is not because the input and output side has isolation, so easily occur the common mode leakage current between the both sides.Although it is not have common mode disturbances output from principle that some inversion topologicals are arranged, but because the components and parts in the reality are not desirable, realization inverse switch time that can not be fully desirable, voltage and current control etc. are so these topologys also have the problem of common mode disturbances to some extent.The existence of common mode disturbances has not only affected the Electro Magnetic Compatibility of inverter, also is the problem of the use safety brought.

Summary of the invention

The present invention proposes a kind of circuit, low-cost, the high efficiency inhibition that has realized the common mode disturbances of inverter.

The technical solution used in the present invention is: two electric capacity of series connection (claim that hereinafter these two electric capacity are mid point electric capacity between interchange outlet side the two poles of the earth, C3 among Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 and C4), be connected electric capacity between their mid point and the direct current input and (claim that hereinafter this electric capacity is common mode capacitance, C1 among Fig. 1, Fig. 2, Fig. 4, Fig. 5 and C2, the C2 among Fig. 3); The capacitance of two mid point electric capacity is identical; Common mode capacitance can be connected between the positive pole of the mid point of two mid point electric capacity and direct current input (C1 among Fig. 1, Fig. 2, Fig. 4, Fig. 5), or between the negative pole that mid point and the direct current of two mid point electric capacity are inputted (C2 in the accompanying drawing), two common mode capacitance need one at least, or exist simultaneously; When adopting single common mode capacitance, need between the true negative pole of direct current input side, increase flat wave capacitor (C0 among Fig. 1, Fig. 3); Increase the common mode reactor (Z2 among Fig. 2, Fig. 5 in the inboard, loop that forms by mid point electric capacity, common mode capacitance and inverter circuit (the DC/AC module in the accompanying drawing), Z3 among Fig. 3) can improve the common code impedance of DC/AC circuit, thereby the reduction common mode noise current reduces the loss that common-mode noise causes; The outside, loop at mid point electric capacity, common mode capacitance and inverter circuit (the DC/AC module in the accompanying drawing) increases the common mode reactor (Z1 among Fig. 4, Z4 among Fig. 5) can reduce the external common-mode noise of whole system, reduce EMI (electromagnetic radiation) level of system; The common mode reactor can be placed on direct current input side (Z2 among Fig. 2, Fig. 5, the Z1 among Fig. 4), also can be placed on to exchange outlet side (Z4 among Fig. 5, the Z3 among Fig. 3).

The invention has the beneficial effects as follows: realized the inhibition to the inverter common mode disturbances with very simple circuit, lower cost, reduced the EMI of system, and suppressed the common mode disturbances between the non-isolated inverter input and output side, improved the performance of non-isolated inverter.

Description of drawings

This specification has five accompanying drawings:

Fig. 1 adopts inverter example one of the present invention: without common mode reactor, two common mode capacitance;

Fig. 2 adopts inverter example two of the present invention: built-in, the two common mode capacitance of DC side common mode reactor;

Fig. 3 adopts inverter example three of the present invention: built-in, the single common mode capacitance of AC common mode reactor;

Fig. 4 adopts inverter example four of the present invention: external, the two common mode capacitance of DC side common mode reactor;

Fig. 5 adopts inverter example five of the present invention: two common mode reactors, two common mode capacitance.

Embodiment

Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 are several examples of using inverter of the present invention.Two mid point capacitances that exchange outlet side in these examples are identical.When system works, such as inverter circuit (the DC/AC module in the accompanying drawing) in the ideal case, there is not common mode disturbances output, the mid point of two mid point electric capacity keeps constant to the voltage of direct current input side, i.e. voltage constant on the common mode capacitance; If inverter circuit is undesirable, inverter circuit has common mode disturbances output, and at this moment common mode capacitance provides a passage that impedance is little for common mode disturbances output, so the external output of common mode disturbances will diminish; When the inboard increase of the loop common mode reactor (Z2 in the accompanying drawing and Z3) at mid point electric capacity, common mode capacitance and inverter circuit, so just increased the impedance of inverter circuit common mode disturbances, thereby when having reduced external common mode disturbances electric current, reduce the circulation of common mode disturbances on common mode capacitance, reduced the common mode loss; When the loop outside at neutral point, common mode capacitance and inverter circuit increases common mode reactor (Z1 in the accompanying drawing and Z4), so just increased the external common code impedance of common mode disturbances, thereby reduced external common mode leakage current, improved the Electro Magnetic Compatibility of system.

Claims

1. the inverter common mode disturbances suppresses circuit, realized the inhibition to the common mode disturbances output of inverter circuit, it is characterized in that exchanging two mid point electric capacity of series connection between the two poles of the earth of outlet side, the contact between two mid point electric capacity is connected by common mode capacitance with direct-flow input end.

2. inverter common mode disturbances according to claim 1 suppresses circuit, it is characterized in that the capacitance of described two mid point electric capacity is identical.

3. inverter common mode disturbances according to claim 1 suppresses circuit, it is characterized in that described common mode capacitance can be connected between the positive pole of the mid point of two mid point electric capacity and direct current input, or between the negative pole that mid point and the direct current of two mid point electric capacity are inputted, two common mode capacitance can exist simultaneously.

4. inverter common mode disturbances according to claim 1 suppresses circuit, it is characterized in that the inboard common mode reactor that increases in the loop of mid point electric capacity, common mode capacitance and inverter circuit, and this reactor can be placed on DC side, also can be placed on AC.

5. inverter common mode disturbances according to claim 1 suppresses circuit, and it is characterized in that increases the common mode reactor in the outside, loop of mid point electric capacity, common mode capacitance and inverter circuit, and this reactor can be placed on DC side, also can be placed on AC.