CN110868050A

CN110868050A - Dynamic current-sharing control circuit of parallel IGBT

Info

Publication number: CN110868050A
Application number: CN201911287578.9A
Authority: CN
Inventors: 刘彦呈; 庄绪州; 张勤进; 郭昊昊; 刘厶源; 孙凡金; 王川; 魏一
Original assignee: Dalian Maritime University
Current assignee: Dalian Maritime University
Priority date: 2019-12-14
Filing date: 2019-12-14
Publication date: 2020-03-06

Abstract

The invention discloses a dynamic current-sharing control circuit of parallel IGBTs, which comprises a specific structure; the parallel IGBT module and the current-sharing inductance module are used for increasing the capacity; the parallel IGBT module comprises n groups of IGBT half-bridge circuits, wherein n is more than or equal to 2, the connection point of two IGBTs in each IGBT half-bridge circuit is an output end, each IGBT half-bridge circuit comprises an upper bridge arm switch tube and a lower bridge arm switch tube, and the upper bridge arm switch tube S of each IGBT half-bridge circuit₁、S₃、S₅、S₇、…S_2n‑1The PWM signals are the same and drive the lower bridge arm switch tube S₂、S₄、S₆、S₈、…S_2nThe PWM is the same, wherein the upper bridge arm switching tube and the lower bridge arm switching tube are not conducted at the same time. The circuit improves the static and dynamic current sharing precision of the IGBT, the single IGBT does not need to be used in a derating way, and the utilization degree of the single IGBT is improved.

Description

Dynamic current-sharing control circuit of parallel IGBT

Technical Field

The invention relates to the technical field of power electronics, in particular to a dynamic current-sharing control circuit of parallel IGBTs.

Background

The Insulated Gate Bipolar Transistor (IGBT) combines the advantages of a power field effect transistor (MOSFET) and a power transistor, has the advantages of high input impedance, small driving power, good switching characteristic and the like, is an ideal fully-controlled device, and is widely applied to power electronic equipment. However, for high-voltage and high-power electronic equipment, the capacity of a single IGBT still cannot meet the requirement, and the parallel connection of a plurality of IGBTs becomes an effective way for improving the capacity.

The difference of static and dynamic performances between parallel connection can affect current sharing, and IGBT devices can fail or even damage a main circuit when the current sharing is serious, so that the key of the parallel application of the IGBTs is to ensure the current balance of each IGBT when the switch is dynamic. The reasons for the parallel-connection non-uniform current of the IGBTs mainly include (1) the difference between the resistance component of the direct-current bus side connection point of the parallel-connected IGBTs and the stray inductance L; (2) turn-on threshold voltage V of IGBT module_gethDifference of (A), (B), (C) V_gethThe higher the IGBT is, the later the IGBT is switched on, the different modules have differences; (3) vce (sat) of IGBT chip and V of diode chip_FA difference of (a); (4) the temperature difference of the IGBT modules; (5) the difference of the magnetic field where the IGBT module is located; (6) a difference in gate voltage Vge; (7) the difference in stray inductance in the gate loop.

The existing IGBT parallel connection method with application value is an emitter resistance feedback method and an external inductance method, but the problems of great derating use of the IGBT exist. Therefore, an efficient multi-IGBT parallel current sharing method and circuit are provided.

Disclosure of Invention

According to the problems in the prior art, the invention discloses a dynamic current-sharing control circuit of a parallel IGBT, which comprises a specific structure;

the method comprises the following steps: the parallel IGBT module and the current-sharing inductance module are used for increasing the capacity;

the parallel IGBT module comprises n groups of IGBT half-bridge circuits, wherein n is more than or equal to 2, the connection point of two IGBTs in each IGBT half-bridge circuit is an output end, each IGBT half-bridge circuit comprises an upper bridge arm switch tube and a lower bridge arm switch tube, and the upper bridge arm switch tube S of each IGBT half-bridge circuit₁、S₃、S₅、S₇、…S_2n-1The PWM signals are the same and drive the lower bridge arm switch tube S₂、S₄、S₆、S₈、…S_2nThe PWM is the same, wherein the upper bridge arm switching tube and the lower bridge arm switching tube are not conducted at the same time;

the current-sharing inductance module comprises n common-mode inductors, the input ends of the common-mode inductors are synonym ends of two coils, the synonym ends of the two coils are respectively connected to the output ends of adjacent IGBT half-bridge circuits in the parallel IGBT module with increased capacity, current sharing between the adjacent IGBT half-bridge circuits is controlled to be balanced by one common-mode inductor, and the inductances L of the two coils of the common-mode inductors are controlled to be balanced by the common-mode inductor_kA＝L_kBMutual inductance M between two coils_k＝L_kA＝L_kB。

Due to the adoption of the technical scheme, the dynamic current-sharing control circuit of the parallel IGBT improves the static and dynamic current-sharing precision of the IGBT on the basis of not increasing the complexity of a driving circuit, and improves the utilization degree of a single IGBT without reducing the use amount of the single IGBT. The thermal stress difference of the switch tubes caused by the unbalanced current of the parallel IGBTs is reduced, the damage probability of a single IGBT is reduced, and the service life of the IGBT is prolonged.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic diagram of a current sharing control circuit of the present invention with two half-bridge circuits connected in parallel;

fig. 2 is a schematic diagram of a current-sharing control circuit in which n half-bridge circuits are connected in parallel according to the present invention.

Detailed Description

In order to make the technical solutions and advantages of the present invention clearer, the following describes the technical solutions in the embodiments of the present invention clearly and completely with reference to the drawings in the embodiments of the present invention:

as shown in FIG. 1, in the dynamic current-sharing control circuit of parallel IGBTs, two half-bridges in the circuit both adopt IGBTs of the same type, parameters are kept consistent, and an upper bridge arm switch tube S₁And S₃The PWM signals are the same and drive the lower bridge arm switch tube S₂And S₄The PWM is the same, and the upper and lower bridge arms are not conducted at the same time. The current between the two half bridges is balanced by a current sharing common mode inductor. Inductance L of two coils of common mode inductance_A＝L_BMutual inductance between two coils M ═ L_A＝L_B。

When the upper bridge arm is conducted, the voltage of the positive pole and the output end of the 1 st phase is as follows:

positive and output terminal voltage of phase 2:

when the two half-bridges are equal in current, U_PA1＝U_SAT1，U_PA2＝U_SAT2；

The inductive reactance of each phase is 0 during current sharing;

parallel connection time terminalVoltage U_PA1＝U_PA2；

Namely, it is

Through the coupling effect of the current sharing inductor, the current change of any phase can cause the current change of the other phase, so that the dynamic current sharing of the current between the two phases is realized.

When the power requirement cannot be met even by connecting two half-bridges in parallel, the number of parallel half-bridges needs to be extended on a two-phase basis, as shown in fig. 2. Upper bridge arm switching tube S of n groups of IGBT half-bridge circuits₁、S₃、S₅、S₇、…S_2n-1The PWM signals are the same and drive the lower bridge arm switch tube S₂、S₄、S₆、S₈、…S_2nThe PWM is the same, and the upper and lower bridge arms are not conducted at the same time. The current sharing inductor consists of n-1 common mode inductors, and the current sharing between two adjacent phases is balanced by one common mode inductor. Inductance L of two coils of common mode inductance_kA＝L_kBMutual inductance M between two coils_k＝L_kA＝L_kB. Wherein k represents the kth phase;

voltage per phase

When the transient currents of the phases are equal to each other, U_PAk＝U_SATk，U_ANk＝U_SATk；

Due to mutual influence of mutual inductance among phases, the inductive reactance of each phase is 0 during current sharing;

when the transient current of the k-th phase is increased,

in this case, the k-1 th phase has,

in this case, the (k + 1) th phase has,

when one phase of current is increased, the inductive reactance of the current path is increased to block the current from increasing, the inductive reactance of the adjacent phase is reduced, and the current is increased until all the phases are equalized;

the inductance between the k phase and the k +1 phase is L_kA+L_kB+2M_kAnd prevents the generation of interphase circulating current.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. A dynamic current-sharing control circuit of parallel IGBT is characterized by comprising: the parallel IGBT module (1) and the current sharing inductance module (2) are used for increasing the capacity;

the parallel IGBT module (1) comprises n groups of IGBT half-bridge circuits (11), wherein n is more than or equal to 2, the connection point of two IGBTs in each IGBT half-bridge circuit (11) is an output end, each IGBT half-bridge circuit (11) comprises an upper bridge arm switch tube and a lower bridge arm switch tube, and the upper bridge arm switch tube S of each IGBT half-bridge circuit (11)₁、S₃、S₅、S₇、…S_2n-1The PWM signals are the same and drive the lower bridge arm switch tube S₂、S₄、S₆、S₈、…S_2nThe PWM is the same, wherein the upper bridge arm switching tube and the lower bridge arm switching tube are not conducted at the same time;

the current-sharing inductance module (2) comprises n common-mode inductors (21), the input end of each common-mode inductor (21) is a synonym end of two coils, the synonym ends of the two coils are respectively connected to the output end of an adjacent IGBT half-bridge circuit (11) in the parallel IGBT module (1) with increased capacity, current sharing between the adjacent IGBT half-bridge circuits (11) is controlled and balanced by one common-mode inductor, and the inductance L of the two coils of each common-mode inductor (21) is controlled and balanced by the common-mode inductor_kA＝L_kBMutual inductance M between two coils_k＝L_kA＝L_kB。