Multi-tube parallel current equalization circuit structure and power electronic equipment thereof

Abstract

The utility model discloses a multi-tube parallel current equalization circuit structure, which comprises a multi-tube parallel circuit formed by a plurality of MOS (Metal Oxide Semiconductor) tubes which are connected in parallel, and the input end and / or the output end of the multi-tube parallel circuit are / is respectively connected with a current equalization conductive strip. The current balancing bus bar at the input end is used for adjusting the current path of the input current at the MOS tubes connected in parallel so as to balance the current distribution, and the current balancing bus bar at the output end is used for gathering the current paths flowing out of the MOS tubes connected in parallel. The structure provided by the scheme can effectively balance the current distribution when a plurality of MOS tubes are connected in parallel, and ensures that the magnitude of each current passing through all the MOS tubes connected in parallel is basically consistent when the MOS tubes connected in parallel are started, so that the reliability of the MOS tubes connected in parallel is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of power electronics, and particularly relates to a multi - tube parallel current equalization circuit structure and a power electronic device thereof. Background Art

[0002] In power electronics technology, MOS transistors are widely used in applications such as switching power supplies, frequency converters, and motor drives due to their high switching speed, low on - resistance, and good high - frequency characteristics.

[0003] In practical applications, in order to improve power and reliability, multiple MOS transistors are often connected in parallel. However, in the existing simple direct parallel connection method for multi - tube parallel connection, due to the differences in the physical distances and connection methods between MOS transistors, the distances of each MOS transistor are not equal, and the impedances are not equal. Specifically, among the parallel - connected MOS transistors, the first MOS transistor is the closest and has the smallest impedance, while the last MOS transistor is the farthest and has the largest impedance. Therefore, the MOS transistor closest to the power supply bears the largest current, while the MOS transistor farthest away bears the smallest current, resulting in uneven current distribution in the entire parallel circuit. As the number of parallel - connected MOS transistors increases, the non - uniformity of current distribution becomes more obvious, leading to some MOS transistors being easily damaged due to excessive current, affecting the stability and reliability of the entire circuit. Summary of the Utility Model

[0004] The purpose of the utility model is to solve the above problems and provide a multi - tube parallel current equalization circuit structure, which can effectively equalize the current distribution when multiple MOS transistors are connected in parallel, and improve the stability and reliability of the circuit;

[0005] Another purpose of the utility model is to provide a power electronic device applying the multi - tube parallel current equalization circuit structure.

[0006] To achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A multi - tube parallel current equalization circuit structure includes a multi - tube parallel circuit composed of multiple MOS transistors connected in parallel. Current equalization conductive bars are respectively connected to the input end and / or output end of the multi - tube parallel circuit. The current equalization conductive bar at the input end is used to adjust the current path of the input current at multiple MOS transistors connected in parallel to equalize the current distribution;

[0008] The current equalization conductive bar at the output end is used to aggregate the current paths flowing out from multiple MOS transistors connected in parallel.

[0009] This solution can effectively divide the current of each MOS tube by the design of current balancing conductive strips, ensuring that the current passing through each MOS tube in parallel is consistent when turned on, thereby improving the reliability of the MOS tubes after parallel connection.

[0010] In the above-mentioned multi-transistor parallel current balancing circuit structure, the current balancing conductive strip at the input end has at least two conductive branches to divide the input current into at least two current paths to flow into corresponding MOS transistors respectively.

[0011] In the above-mentioned multi-tube parallel current balancing circuit structure, the current balancing conductive strip at the output end has at least two conductive branches to receive at least two currents from MOS tubes and output the currents after summing them up.

[0012] In the above-mentioned multi-tube parallel current balancing circuit structure, the current path impedances of multiple parallel-connected MOS tubes are adjusted to be basically consistent by adjusting the number, length and position of each conductive branch of the current balancing conductive strip to balance the current distribution. Basically consistent does not require complete consistency, and the difference can be controlled within 20%.

[0013] In the above multi-tube parallel current balancing circuit structure, the number m of conductive branches of each current balancing conductive strip is n represents the number of MOS tubes connected in parallel in the multi-tube parallel circuit, n≥3, and each conductive branch corresponds to at least one MOS tube.

[0014] In the above-mentioned multi-transistor parallel current balancing circuit structure, each current balancing conductive strip has a central conductive portion, the central conductive portion is used to connect the input end or the output end, and each conductive branch extends from the central conductive portion;

[0015] The central conductive portion of the current balancing conductive strip is located in the middle of each MOS tube of the corresponding multi-tube parallel circuit to balance the impedance of the current path from the central conductive portion to each MOS tube;

[0016] When each conductive branch corresponds to at least two MOS transistors, the conductive branch has a branch center, and the branch center is located in the middle of the at least two MOS transistors corresponding to the conductive branch, so as to balance the impedance of the current path from the central conductive part to the corresponding MOS transistors;

[0017] The number of MOS tubes corresponding to each conductive branch of each current balancing conductive strip is equal or differs by one. Preferably, the number of MOS tubes is equal when the number of conductive branches is evenly divided by the number of conductive branches, otherwise the number of MOS tubes differs by one.

[0018] In the above multi-tube parallel current balancing circuit structure, the number n of MOS tubes connected in parallel in the multi-tube parallel circuit is 6, and the number m of conductive branches of each current balancing conductive strip is 2.

[0019] In the above multi-tube parallel current equalization circuit structure, the current equalization conductive strip is generally made of copper, or can be made of other materials with good conductivity.

[0020] In the above multi-tube parallel current equalization circuit structure, the multi-tube parallel current equalization circuit structure is arranged on a copper-clad PCB board. The current equalization conductive strip is formed by soldering a copper strip on the copper-clad layer of the PCB board. The copper foil of the PCB board itself is relatively thin and has a certain over-current capacity. However, as the distance increases, the impedance becomes very large under large current. After soldering a copper strip on the copper-clad layer, the impedance becomes smaller. Adjusting the distance between the copper strip and the MOS tube can effectively adjust the impedance in the entire current loop.

[0021] A power electronic device, which is used in a switching power supply, an inverter or a motor drive circuit, includes a multi-tube parallel current equalization circuit structure.

[0022] Compared with the existing technology, the advantages of the present utility model are as follows:

[0023] In this solution, after the current is shunted through the copper strip to adjust the impedance, it enters the MOS tube to balance the impedance of each mutually parallel MOS tube, thereby realizing the current of each MOS tube, and the loss risk caused by uneven current can be reduced.

[0024] It can effectively average the current of each MOS tube, ensure that the current passing through each MOS tube is basically the same when all the parallel MOS tubes are turned on, thereby improving the reliability of the MOS tubes after parallel connection. Brief Description of the Drawings

[0025] Figure 1 is the circuit structure block diagram of the multi-tube parallel current equalization circuit structure of this solution;

[0026] Figure 2 One implementation method of the current equalization conductive strip in the multi-tube parallel current equalization circuit structure of this solution;

[0027] Figure 3 is the circuit structure diagram of applying the multi-tube parallel current equalization circuit structure of this solution to a motor drive circuit;

[0028] Figure 4 is the circuit structure of applying the multi-tube parallel current equalization circuit structure of this solution to a motor drive circuit Figure 2 .

[0029] In the figure: multi-tube parallel circuit 1; current equalization conductive strip 2; each conductive branch 21; branch center 22; central conductive part 23; terminal 4. Detailed Embodiment

[0030] The present utility model will be further described below with reference to the accompanying drawings.

[0031] AsFigure 1 and Figure 2 As shown in Figure 2 , this embodiment provides a multi - tube parallel current equalization circuit structure, which includes a multi - tube parallel circuit 1 composed of multiple MOS tubes 3 connected in parallel. Current equalization conductive bars 2 are respectively connected to the input end and / or output end of the multi - tube parallel circuit 1. The current equalization conductive bar 2 at the input end is used to adjust the current path of the input current at multiple MOS tubes 3 connected in parallel to equalize the current distribution. The current equalization conductive bar 2 at the output end is used to aggregate the current paths flowing out from multiple MOS tubes 3 connected in parallel.

[0032] Specifically, the current equalization conductive bar 2 is made of a material with good conductivity and weldability, such as copper. The multi - tube parallel current equalization circuit structure is arranged on a PCB board, and the current equalization conductive bar 2 is formed by welding copper bars on the copper - clad layer of the PCB board. The current equalization conductive bar 2 at the input end has at least two conductive branches 21 to divide the input current into at least two current paths and flow into the corresponding MOS tubes 3 respectively. The current equalization conductive bar 2 at the output end has at least two conductive branches 21 to receive at least two currents from the MOS tubes 3, aggregate the currents and then output. By adjusting the number, length and position of each conductive branch 21 of the current equalization conductive bar 2, the current path impedance of multiple MOS tubes 3 connected in parallel is made basically the same to equalize the current distribution. The copper - clad layer of the PCB board has a relatively thin copper skin and has a certain over - current capacity. However, as the distance increases, the impedance becomes very large under large current. After welding copper bars on the copper - clad layer, the impedance becomes smaller, and adjusting the distance between the copper bar and the MOS tube 3 can effectively adjust the impedance in the whole current loop.

[0033] Preferably, the number m of the conductive branches 21 of each current equalization conductive bar 2 is where n represents the number of MOS tubes 3 connected in parallel in the multi - tube parallel circuit 1, n≥3, and each conductive branch 21 corresponds to at least one MOS tube 3. Figure 1 In Figure 1 , the number n of MOS tubes 3 connected in parallel in the multi - tube parallel circuit 1 is 6, and the number m of the conductive branches 21 of each current equalization conductive bar 2 is 2. When put into use, the number of MOS tubes 3 is determined according to needs, and the number of the conductive branches 21 of the current equalization conductive bar 2 is determined by comprehensively considering the number of MOS tubes and the current equalization requirements.

[0034] Specifically, each current equalization conductive bar 2 has a central conductive part 23, and the central conductive part 23 is used to connect the input end or the output end, and each conductive branch 21 extends from the central conductive part 23. As Figure 1 shown in Figure 1 , the central conductive part 23 of the current equalization conductive bar 2 is located at the middle position of each MOS tube 3 in the corresponding multi - tube parallel circuit 1 to equalize the current path impedance from the central conductive part 23 to each MOS tube 3.

[0035] Preferably, when each conductive branch 21 corresponds to at least two MOS transistors 3, the conductive branch 21 has a branch center 22, and the branch center 22 is located at the middle position of the at least two MOS transistors 3 corresponding to the conductive branch 21 to balance the current path impedance from the central conductive portion 23 to the respective MOS transistors 3. The specific form of the conductive branch is determined according to the actual situation based on the principle of adjusting the current path and balancing the impedance, and it can be, for example, Figure 1 the flat "T" - shaped structure shown, or it can be, for example, Figure 3 the "one" - character inclined structure shown, etc.

[0036] The number of MOS transistors 3 corresponding to each conductive branch 21 of each current - balancing conductive bar 2 is equal or differs by one. When the number of MOS transistors 3 can be better divided by the number of conductive branches 21, they are equal; otherwise, they differ by one. The number of MOS transistors 3 and the conductive branches 21 can be comprehensively determined so that the number of MOS transistors 3 can be better divided by the number of conductive branches 21, so that the number of MOS transistors 3 corresponding to each conductive branch 21 of each current - balancing conductive bar 2 is equal.

[0037] The multi - transistor parallel current - balancing circuit structure provided by this solution can be applied to power electronic devices such as switching power supplies, frequency converters, or motor drive circuits, etc. Here, taking the application in a motor drive circuit as an example for illustration, Figure 3 and Figure 4It is a diagram of the three-phase motor drive layout from different perspectives, which is divided into three items A / B / C. The current flows into the three phases ABC respectively, and flows out to the other phases ABC through the motor coils. Specifically, the positive and negative poles of the PCB board are powered, and the current flows into the A-phase input current balancing conductive strip 2 through the positive copper bar. The current is divided into two paths and flows to the corresponding upper bridge MOS tube respectively. After flowing through the MOS tube, the current enters the MOS tube output current balancing conductive strip 2 and then merges into the middle terminal 4 and flows out to the motor coil. The motor coil flows into the B-phase terminal 4 or into the C-phase terminal 4. The current enters the lower bridge MOS tube through the current balancing conductive strip 2, and the current flows out from the lower bridge MOS tube to the current balancing conductive strip 2. The current balancing conductive strip 2 is divided into two paths and summed up, and the outflow is summed up to the negative pole. In the present embodiment, the central conductive portion 23 of the current balancing conductive strip 2 from the upper bridge MOS tube to the terminal 4 is the corresponding terminal 4, and the two conductive branches 21 extend outward from the corresponding terminal 4 and toward the upper bridge MOS tube, and the two conductive branches 21 form an angle greater than 120 degrees and less than 170 degrees at the terminal toward the upper bridge MOS tube to adjust the current path balance of the current path impedance of each corresponding upper bridge MOS tube 3 to the corresponding terminal 4; similarly, the central conductive portion 23 of the current balancing conductive strip 2 from the terminal 4 to the lower bridge MOS tube is the corresponding terminal 4, and the two conductive branches 21 extend outward from the terminal 4 and toward the lower bridge MOS tube, and the two conductive branches 21 form an angle greater than 120 degrees and less than 170 degrees at the terminal toward the lower bridge MOS tube to adjust the current path impedance of the current path balance central conductive portion 23 to each corresponding lower bridge MOS tube 3. In this way, the three-phase motor drive circuit can use multiple MOS tubes in parallel in each bridge to improve the reliability and processing capability of the drive circuit. At the same time, the balancing circuit structure provided by this solution can achieve current balancing of parallel circuits with similar impedances, thereby improving the processing capability and reliability of the drive circuit by parallel MOS tubes while avoiding the impact of inconsistent current sizes between parallel MOS tubes on the stability and reliability of the entire circuit.

[0038] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways without departing from the spirit of the present invention.

[0039] Although the terms such as multi-tube parallel circuit 1, current balancing conductive strip 2, conductive branches 21, branch center 22, and central conductive part 23 are often used in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the utility model. It is contrary to the spirit of the utility model to interpret them as any additional restrictions.

Claims

1. A multi-tube parallel current equalization circuit structure, comprising a multi-tube parallel circuit (1) composed of multiple MOS tubes (3) connected in parallel, characterized in that, The input end and / or the output end of the multi-tube parallel circuit (1) are respectively connected with a current equalizing conductive bar (2). The current equalizing conductive bar (2) at the input end is used to adjust the current path of the input current at multiple parallel-connected MOS tubes (3) to equalize the current distribution; The current equalizing conductive bar (2) at the output end is used to aggregate the current paths flowing out from multiple parallel-connected MOS tubes (3).

2. The multi-tube parallel current equalization circuit structure according to claim 1, wherein , The current equalizing conductive bar (2) at the input end has at least two conductive branches (21) to divide the input current into at least two current paths and flow into the corresponding MOS tubes (3) respectively.

3. The multi-tube parallel current equalization circuit structure according to claim 2, wherein , The current equalizing conductive bar (2) at the output end has at least two conductive branches (21) to receive at least two currents from the MOS tubes (3), aggregate the currents and then output.

4. The multi-tube parallel current equalization circuit structure according to claim 1, wherein , By adjusting the number, length and position of each conductive branch (21) of the current equalizing conductive bar (2), the current path impedances of multiple parallel-connected MOS tubes (3) are made basically the same to equalize the current distribution.

5. The multi-tube parallel current equalization circuit structure according to claim 4, wherein , the number m of conductive branches (21) of each current equalizing conductive bar (2) is n represents the number of MOS transistors (3) connected in parallel in the multi-transistor parallel circuit (1), n ≥ 3, and each conductive branch (21) corresponds to at least one MOS transistor (3).

6. The multi-tube parallel current equalization circuit structure according to claim 5, characterized in that , Each current equalizing conductive bar (2) has a central conductive part (23). The central conductive part (23) is used to connect the input end or the output end, and each conductive branch (21) extends from the central conductive part (23); The central conductive part (23) of the current equalizing conductive bar (2) is located at the middle position of each MOS tube (3) of the corresponding multi-tube parallel circuit (1) to equalize the current path impedances from the central conductive part (23) to each MOS tube (3); When each conductive branch (21) corresponds to at least two MOS tubes (3), the conductive branch (21) has a branch center (22). The branch center (22) is located at the middle position of at least two MOS tubes (3) corresponding to the conductive branch (21) to equalize the current path impedances from the central conductive part (23) to the corresponding MOS tubes (3); The number of MOS tubes (3) corresponding to each conductive branch (21) of each current equalizing conductive bar (2) is equal or differs by one.

7. The multi-tube parallel current equalization circuit structure according to claim 5, characterized in that , The number n of the MOS tubes (3) connected in parallel in the multi-tube parallel circuit (1) is 6, and the number m of the conductive branches (21) of each current equalizing conductive bar (2) is 2.

8. The multi-tube parallel current equalization circuit structure according to any one of claims 1-7, characterized in that , The current equalizing conductive bar (2) is made of a material with good conductivity and weldability.

9. The multi-tube parallel current equalization circuit structure according to claim 6, characterized in that , The multi-tube parallel current equalizing circuit structure is arranged on a PCB board, and the current equalizing conductive bar (2) is formed by welding a copper bar on the copper-clad layer of the PCB board.

10. A power electronic device, characterized in that, It is used for a switching power supply, an inverter or a motor drive circuit, and includes the multi-tube parallel current equalizing circuit structure according to any one of claims 1-9.

Images