Due to the high production cost, the price of 1200V I GB T module greater than 400A in the market. As for the standard 1200V, 200-400A 62mm module, due to the relatively stable technology and product, good product versatility and easy to replace, it is the most economical way to use multiple standard IGBT modules in parallel to improve the current rating at this stage.However, due to the inconsistency of IGBT own parameters and the possible asymmetry caused by circuit layout, it is not a simple job to use IGBT module for parallel design. Unreasonable selection of components as parallel or components can easily fail the device and damage the lines on the main system.Therefore, this paper, from the successful experience of the application department in the client and the test equipment in the factory, and proposes the importance of using star IGBT module for parallel design.

Modules generally larger than 100A themselves are made of several chips in parallel, although manufacturers can use chips on the same wafer to connect in parallel to reduce the parameter difference of the module itself.However, it still needs to take into account the individual differences between the resulting module parameters.At the same time, the symmetry of the circuit is a very important influence on parallel, which can be expounded from the two aspects of static and dynamic, from the difference of parameters and the difference of circuit symmetry.

Factors affecting the parallel and static mean flow of modules

In actual use, the working state of IGBT module is mainly in the conduction and switch transient, and the conduction stage is relatively long and the current is large. This section has a great impact. Start from the static conduction state.

1.1. The main reasons for affecting the parallel average flow of the module are the following 4 points

A) Effect of saturated pressure drop Vce (sat)

The b) Effect of the impedance asymmetry of the parallel power circuit

The c) Effect of the gate pole drive voltage Vge

The d) Effect of the on voltage V th

e) Effect of diode conduction pressure drop Vf

1) Problems with different Vce (sat) in parallel:

In many cases, the average person thinks that the Vce (sat) generated by the current flowing through the IGBT is a fixed value, which is a misconception. Vce (sat) actually refers to the pressure drop generated by the rated current.For IGBT, the conduction pressure drop is a function of the current at the same V ge.

For the two IGBT connected in parallel, the pressure drop generated by the positive guide pass when opening the steady state is equal.Thus, the equilibrium of the current distribution depends on the differences in the output characteristics of the various IGBT s in parallel.

Figure 1 shows the difference in the current distribution of two different output characteristic IGBT s in parallel (the same Vce of two IGBT in parallel).