CN202940726U

CN202940726U - Common-mode current suppression circuit

Info

Publication number: CN202940726U
Application number: CN 201220650536
Authority: CN
Inventors: 魏秀梅
Original assignee: YUYAO YIWEI ELECTRONIC TECHNOLOGY Co Ltd
Current assignee: YUYAO YIWEI ELECTRONIC TECHNOLOGY Co Ltd
Priority date: 2012-11-28
Filing date: 2012-11-28
Publication date: 2013-05-15
Anticipated expiration: 2022-11-28

Abstract

The utility model discloses a common-mode current suppression circuit. A push-pull circuit composed of a first field effect tube Q1 and a second field effect tube Q2 which are complementary and symmetrical constitutes a parallel compensation circuit, a winding 3 of a common-mode transformer senses a common-mode current, the common-mode current is converted into a corresponding common-mode voltage by a sampling resistor R so as to be conveniently processed by an intelligent control unit MCU, the push-pull compensation circuit composed of the first field effect tube Q1 and the second field effect tube Q2 is controlled to generate a compensation current which is equal in magnitude but opposite in direction with a common-mode current source, and the compensation current is fed back to the circuit so as to achieve the purpose of common-mode current suppression. The common-mode current suppression circuit has the advantages that the volume of a hardware circuit is reduced, the flexibility is good, and the filtering ability is strong.

Description

A kind of common mode current suppresses circuit

Technical field

The utility model belongs to EMC (Electromagnetic Compatibility) electromagnetic compatibility field, is specifically related to a kind of common mode current and suppresses circuit.

Technical background

Along with developing rapidly of electronics, electric, communication, computer technology, Electro Magnetic Compatibility more and more causes people's great attention in the significance in industry, scientific research, civilian and military field.Wherein conduction and Radiative EMI may cause and near other electronic equipment or common source between produce serious electromagnetic interference problem, even may affect health.Therefore the various worlds and domestic electromagnetic compatibility standard and standard are executed in succession, make EMI become a problem anxious to be resolved.Common mode EMI common dominate in total EMI wherein.Common mode EMI is derived from high dv/dt position in converter circuit (namely having the position of the transition voltage that is caused by devices switch), by phase line, parasitic capacitance and ground consist of the flow cycle of common mode current over the ground.In addition, the loop area that common mode current is flowed through is large more than differential mode, so common mode current while or the main reason of high frequency radiation interference.

Main by passive filter circuit filtering common mode electromagnetic interference in prior art, circuit shown in Figure 1 is exactly existing common mode filtering circuit, be commonly referred to electromagnetic interface filter, electromagnetic interface filter mainly relies on electric capacity, and the passive devices such as inductance carry out filtering, its volume is large, cost is high, and its filtering performance not only depends on filter itself, and depends on noise source and noise loading impedance, electromagnetic interface filter wants to give full play to performance, and impedance is coupling well.For power electronic equipment, the noise source of electromagnetic interface filter is exactly device itself, and the noise source impedance changes and changes along with switch topology.Noise loading is electrical network, and impedance conditions is also ceaselessly changing.Thereby when electromagnetic interface filter was used for actual device, attenuation was difficult to determine, even also can produce negative interaction at some Frequency point, and its filter capacity is limited.In case and the filter place in circuit just can't revise, very flexible.

The utility model content

The utility model is exactly in order to overcome top deficiency, has proposed a kind of common mode current and has suppressed circuit, utilizes software control method to reduce the hardware circuit volume, and flexibility is good, and filter capacity is strong.

In order to solve the problems of the technologies described above, the utility model by the following technical solutions: a kind of common mode current suppresses circuit, comprises common mode transformer L, sampling resistor R, intelligent control unit M C U, the first field effect transistor Q 1, the second field effect transistor Q 2, the first capacitor C y 1, the second capacitor C y 2, the 3rd capacitor C 1, the four capacitor C 2, the five capacitor C 0, input anode Vin+, input negative terminal Vin-, output plus terminal Vout+, output negative terminal Vout-and voltage of direct-flow voltage regulation source V C.the first capacitor C y 1 one termination input anode Vin+ and common mode transformer L Same Name of Ends, other end ground connection, the second capacitor C y 2 one termination input negative terminal Vin-and common mode transformer L Same Name of Ends, other end ground connection, sampling resistor R connects common mode transformer L one winding two ends, the first field effect transistor Q1 grid connects the second field effect transistor Q2 grid and accesses intelligent control unit MCU, the first field effect transistor Q1 source electrode connects the second field effect transistor Q2 source electrode and accesses intelligent control unit MCU, the 5th capacitor C 0 one termination the first field effect transistor Q1 source electrodes, other end ground connection, voltage of direct-flow voltage regulation source V C positive pole connects the first field effect transistor Q1 drain electrode, voltage of direct-flow voltage regulation source V C negative pole connects the second field effect transistor Q2 drain electrode, the 3rd capacitor C 1 one termination output plus terminal Vout+, another termination voltage of direct-flow voltage regulation source V C is anodal, the 4th capacitor C 2 one termination output negative terminal Vout-, another termination second field effect transistor Q2 drain electrode.

During circuit working, by inducing common mode current on common mode transformer winding 3, be transformed into corresponding common-mode voltage so that intelligent control unit M C U processes through sampling resistor R, the offset current of recommending compensating circuit generation and common mode current source opposite sign but equal magnitude that control is comprised of the first field effect transistor Q 1 and the second field effect transistor Q 2, then feed back to through the 3rd capacitor C 1 and the 4th capacitor C 2 purpose that reaches the inhibition common mode current in circuit.

Wherein, described moding depressor L altogether has 3 windings, winding 1, winding 2, winding 3.

Wherein, described common mode transformer L winding 1, in winding 2 places in circuit, wherein winding 1 one end 1A meet input anode Vin+ other end 1B and meet output plus terminal Vout+, winding 2 one end 2A meet input negative terminal Vin-other end 2B and meet output negative terminal Vout-, winding 3 one end 3A connect sampling resistor R one end, and winding 3 other end 3B connect the sampling resistor R other end.Sampling resistor R induces common mode current, through being transformed into corresponding common-mode voltage so that intelligent control unit M C U processes.

Wherein, the 3A end of the 2A end of the 1A of described common mode transformer winding 1 end and winding and winding 3 is Same Name of Ends.

Wherein, described the first field effect transistor Q1 is the positive-negative-positive structure, and the second field effect transistor Q 2 is N P N structures, and the first field effect transistor Q1 recommends compensating circuit with the second field effect transistor Q 2 consistent compositions of switch performance.

Compared with prior art, the beneficial effects of the utility model are:

1, utilize software control method can save hardware circuit, reduce the circuit volume, be convenient to integrated.

2, utilize software control method can make control convenient, the circuit flexibility is strong, is convenient to revise.

3, the simple cost of circuit structure is low, and is economical and practical.

4, it is stronger that circuit suppresses the common mode current ability.

Description of drawings

Fig. 1 is the circuit theory diagrams of existing common mode filtering circuit;

Fig. 2 is that the utility model common mode current suppresses the circuit embodiments schematic diagram.

Embodiment

Below in conjunction with drawings and Examples, the utility model is further illustrated.

With reference to accompanying drawing 2, the utility model common mode current suppresses the circuit embodiments schematic diagram.

Common mode current as a kind of in Fig. 2 suppresses circuit, comprises common mode transformer L, sampling resistor R, intelligent control unit M C U, the first field effect transistor Q 1, the second field effect transistor Q 2, the first capacitor C y 1, the second capacitor C y 2, the three capacitor C 1, the 4th capacitor C 2, the 5th capacitor C 0, input anode Vin+, input negative terminal Vin-, output plus terminal Vout+, output negative terminal Vout-and voltage of direct-flow voltage regulation source V C.it is characterized in that the first capacitor C y 1 one termination input anode Vin+ and common mode transformer L Same Name of Ends, other end ground connection, the second capacitor C y 2 one termination input negative terminal Vin-and common mode transformer L Same Name of Ends, other end ground connection, sampling resistor R connects common mode transformer L one winding two ends, the first field effect transistor Q1 grid connects the second field effect transistor Q2 grid and accesses intelligent control unit MCU, the first field effect transistor Q1 source electrode connects the second field effect transistor Q2 source electrode and accesses intelligent control unit MCU, the 5th capacitor C 0 one termination the first field effect transistor Q1 source electrodes, other end ground connection, voltage of direct-flow voltage regulation source V C positive pole connects the first field effect transistor Q1 drain electrode, voltage of direct-flow voltage regulation source V C negative pole connects the second field effect transistor Q2 drain electrode, the 3rd capacitor C 1 one termination output plus terminal Vout+, another termination voltage of direct-flow voltage regulation source V C is anodal, the 4th capacitor C 2 one termination output negative terminal Vout-, another termination second field effect transistor Q2 drain electrode. common mode transformer L has 3 windings, winding 1, winding 2, winding 3. common mode transformer L windings 1, in winding 2 places in circuit, wherein winding 1 one end 1A meet input anode Vin+ other end 1B and meet output plus terminal Vout+, winding 2 one end 2A meet input negative terminal Vin-other end 2B and meet output negative terminal Vout-, winding 3 one end 3A connect sampling resistor R one end, winding 3 other end 3B connect the sampling resistor R other end.By inducing common mode current on common mode transformer winding 3, be transformed into corresponding common-mode voltage so that intelligent control unit M C U processes through sampling resistor R, the offset current of recommending compensating circuit generation and common mode current source opposite sign but equal magnitude that control is comprised of the first field effect transistor Q 1 and the second field effect transistor Q 2, then feed back to through the 3rd capacitor C 1 and the 4th capacitor C 2 purpose that reaches the inhibition common mode current in circuit.

Parameter designing and device are selected:

1. the external dc voltage of voltage regulation VC energy of circuit Injection Current that affords redress, voltage should be more than or equal to 8V.

2. coupling capacitance C1 when considering compensating circuit work, the series impedance of C2 and output capacitance C0 can be born DC bus-bar voltage, and coupling capacitance C 1 and C 2 must select high voltagehigh frequency electric capacity for this reason.

3. output capacitance C o should select high voltagehigh frequency electric capacity.

Common mode transformer be exactly increased a winding on the basis of common mode inductance and on winding one in parallel detect resistance R, the proportional relation of the high-frequency voltage signal that forms on resistance and common mode current.So need according to the size of common mode current and the turn ratio that requires Design of Transformer of high frequency voltage.Reduce the stray capacitance of common mode transformer armature winding as far as possible, prevent that high-frequency current from directly flowing through transformer by stray capacitance.In addition, the common mode transformer armature winding can bear the inverter load current.

5. drive circuit design: shunt peaking circuit is the push-pull circuit that is made of mutual symmetry Q 1 and Q 2MOSFET, produces needed common mode compensation electric current for making compensating circuit, will provide suitable PWM to drive signal to push-pull circuit.Want to provide sufficiently high positive voltage when under upper pipe conducting, pipe turn-offs, when pipe was opened under upper pipe turn-offs, to provide sufficiently high negative voltage.Therefore require drive circuit can provide ± driving voltage of 10V.

Claims

1. a common mode current suppresses circuit, comprise common mode transformer (L), sampling resistor (R), intelligent control unit (MCU), the first field effect transistor (Q1), the second field effect transistor (Q2), the first electric capacity (Cy1), the second electric capacity (Cy2), the 3rd electric capacity (C1), the 4th electric capacity (C2), the 5th electric capacity (C0), input anode (Vin+), input negative terminal (Vin-), output plus terminal (Vout+, output negative terminal (Vout-) and voltage of direct-flow voltage regulation source (VC), it is characterized in that: the first electric capacity (Cy1) termination input anode (Vin+) and common mode transformer (L) Same Name of Ends, other end ground connection, the second electric capacity (Cy2) termination input negative terminal (Vin-) and common mode transformer (L) Same Name of Ends, other end ground connection, sampling resistor (R) connects common mode transformer (L) winding two ends, the first field effect transistor (Q1) grid connects the second field effect transistor (Q2) grid and accesses intelligent control unit MCU, the first field effect transistor (Q1) source electrode connects the second field effect transistor (Q2) source electrode and accesses intelligent control unit MCU, the 5th electric capacity (C0) termination the first field effect transistor (Q1) source electrode, other end ground connection, voltage of direct-flow voltage regulation source (VC) positive pole connects the first field effect transistor (Q1) drain electrode, voltage of direct-flow voltage regulation source (VC) negative pole connects the second field effect transistor (Q2) drain electrode, the 3rd electric capacity (C1) termination output plus terminal (Vout+), another termination voltage of direct-flow voltage regulation source (VC) positive pole, the 4th electric capacity (C2) termination output negative terminal (Vout-), another termination the second field effect transistor (Q2) drain electrode.

2. common mode current according to claim 1 suppresses circuit, it is characterized in that: described moding depressor (L) altogether has 3 windings, winding 1, winding 2, winding 3.

3. common mode current according to claim 2 suppresses circuit, it is characterized in that: described common mode transformer L winding 1, in winding 2 places in circuit, wherein winding 1 one end 1A meet input anode Vin+ other end 1B and connect output plus terminal (Vout+), winding 2 one end 2A meet input negative terminal (Vin-) other end 2B and connect output negative terminal (Vout-), winding 3 one end 3A connect sampling resistor (R) end, and winding 3 other end 3B connect sampling resistor (R) other end; Sampling resistor (R) induces common mode current, through being transformed into corresponding common-mode voltage so that intelligent control unit (MCU) is processed.

4. common mode current according to claim 3 suppresses circuit, it is characterized in that: the 3A end of the 1A end of described common mode transformer winding 1 and the 2A end of winding and winding 3 is Same Name of Ends.

5. according to claim 1 or 4 described common mode currents suppress circuit, it is characterized in that: described the first field effect transistor (Q1) is the positive-negative-positive structure, the second field effect transistor (Q2) is the NPN structure, and the first field effect transistor (Q1) is recommended compensating circuit with the consistent composition of the second field effect transistor (Q2) switch performance.