SiC / Si hybrid switch structure

Abstract

The utility model provides a SiC / Si hybrid switch structure. The switch structure is based on a SiC MOSFET series connection structure, two SiC MOSFETs are connected in series to improve the voltage level, and then one Si IGBT is connected in parallel to form a hybrid switch structure. According to the novel structure, the current-carrying capacity and the cost performance of the switch are improved, and meanwhile voltage grade matching of parallel connection of the SiC MOSFET and the Si IGBT is better completed. The novel structure drive has four time degrees of freedom, the rated current level of the SiC MOSFET is reduced to reduce the switch cost, the additional two degrees of freedom hardly introduce additional loss, and the performance advantages of the hybrid switch are guaranteed.

Description

Technical Field

[0001] The utility model belongs to the technical field of hybrid switches, and in particular relates to a SiC / Si hybrid switch structure. Background Art

[0002] Although Si IGBT has been widely studied and applied and has a low price, due to the existence of tail current, its operating frequency is low and the switching loss is large, so it cannot be used in equipment with higher requirements. SiC MOSFET is just complementary to it, with excellent dynamic performance but high price and small current level. With the conductivity modulation effect brought by its own bipolar structure, SiIGBT has lower conduction loss. The hybrid switch aims to combine the advantages of both, and try to solve the problems of low current and high price of SiC MOSFET and low efficiency and difficulty in increasing switching frequency of Si IGBT.

[0003] The traditional hybrid switch connects SiC MOSFET / Si IGBT in parallel and improves dynamic performance by adjusting the driving mode. The principle is to use SiC MOSFET to switch at high speed, use Si IGBT as the main switch, and adjust the driving timing to turn on and off the main switch at zero voltage (ZVS). The existing Hys has greatly improved the current carrying capacity of SiC MOSFET, but it ignores the fact that the high-voltage single chip of SiC MOSFET has not yet been commercialized, while the 6.5kV single chip of Si IGBT has been put into use. Utility Model Content

[0004] The utility model aims to solve the problems in the prior art and proposes a SiC / Si hybrid switch structure.

[0005] The utility model is realized by the following technical scheme. The utility model proposes a SiC / Si hybrid switch structure. The switch structure is based on a SiC MOSFET series structure. Two SiC MOSFETs are first connected in series to increase the voltage level and then a Si IGBT is connected in parallel to form a hybrid switch structure. The hybrid switch structure switches the SiC MOSFET twice and the Si IGBT once in one cycle. The auxiliary function of the MOS tube only works during the switch conversion process and remains turned off during the conduction period of the main switch.

[0006] Beneficial effects of the utility model:

[0007] The utility model proposes a new hybrid switch structure, which improves the current carrying capacity and cost performance of the switch while better matching the voltage level of the SiC MOSFET and Si IGBT in parallel. The new structure drive has four time degrees of freedom, which helps to reduce the rated current level of the SiC MOSFET to reduce the switch cost. At the same time, the additional two degrees of freedom introduce almost no additional loss, ensuring the performance advantage of the hybrid switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a diagram of the traditional switch structure;

[0009] Figure 2 A structural diagram of a SiC / Si hybrid switch provided by the utility model;

[0010] Figure 3 A four-degree-of-freedom driving waveform diagram of a SiC / Si hybrid switch structure provided by the utility model;

[0011] Figure 4 This is a diagram of the hybrid switch commutation process provided by the utility model. DETAILED DESCRIPTION

[0012] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model in conjunction with the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only part of the embodiments of the present utility model, not all of the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present utility model.

[0013] Combination Figure 1-Figure 4 , the utility model proposes a SiC / Si hybrid switch structure, such as Figure 2 As shown, in order to better match the voltage levels between devices while expanding the current, the switch structure is based on the SiC MOSFET series structure. Two SiC MOSFETs are first connected in series to increase the voltage level and then a Si IGBT is connected in parallel to form a hybrid switch structure. The hybrid switch structure switches the SiC MOSFET twice and the Si IGBT once in one cycle. The auxiliary function of the MOS tube only works during the switch conversion process and remains off during the conduction period of the main switch.

[0014] The four-degree-of-freedom driving waveform of the SiC / Si hybrid switch structure is shown in Figure 3 The detailed commutation process is shown in Figure 4As shown in the figure, switching losses only occur at the beginning and end of the commutation process. In one cycle, the SiC MOSFET is switched twice and the Si IGBT is switched once. The auxiliary function of the MOS tube only works during the switching transition and remains off during the main switch on period. There are four variables in the whole process (t 1 -t 4 ), compared with the traditional drive, two more control degrees of freedom are added. The design can make SiC MOSFET have the minimum conduction loss, thereby reducing the selected chip area and further reducing the switch cost. During the switching process, special attention should be paid to the fact that the MOSFET will have a large current oscillation when it is turned on for the first time. During the period when the MOSFET is turned on alone, the load current flows through both ends of it. Its maximum pulse current and junction temperature should be estimated to prevent breakdown. In the model calculation and simulation, the purpose is to minimize the total switching loss. By changing t 1 -t 4 Optimize the hybrid switch driving process.

[0015] The utility model proposes a new hybrid switch structure, which improves the current carrying capacity and cost performance of the switch while better matching the voltage level of the SiC MOSFET and Si IGBT in parallel. The new structure drive has four time degrees of freedom, which helps to reduce the rated current level of the SiC MOSFET to reduce the switch cost. At the same time, the additional two degrees of freedom introduce almost no additional loss, ensuring the performance advantage of the hybrid switch.

[0016] The above is a detailed introduction to a SiC / Si hybrid switch structure proposed in the present invention. Specific examples are used in this article to illustrate the principle and implementation method of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A SiC / Si hybrid switch structure, characterized in that: The switch structure is based on the SiC MOSFET series structure. Two SiC MOSFETs are first connected in series to increase the voltage level and then a Si IGBT is connected in parallel to form a hybrid switch structure. The hybrid switch structure switches the SiC MOSFET twice and the Si IGBT once in one cycle. The auxiliary function of the MOS tube only works during the switch conversion process and remains off during the conduction period of the main switch.

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