Driving method and system for improving reliability of SiC inverter

Abstract

The invention provides a driving method and system for improving the reliability of a SiC inverter. The method belongs to a method for adjusting the junction temperature of a power device in each power unit of the SiC inverter by using an active driving circuit. The needed junction temperature rise and circuit parameters are calculated through the steps 1-7 of low-frequency judgment, junction temperature balance control and junction temperature smooth control, so that the junction temperature of the SiC device in the inverter is increased or decreased. In addition, the method and the system can be used for independently adjusting any power device. The method has the advantages that the SiC inverter is used for conducting junction temperature balance control during stable operation; the average junction temperature of the power device with the worst heat dissipation condition can be reduced; meanwhile, junction temperature smooth control is conducted during low-output-frequency operation of the inverter, junction temperature fluctuation of all the power devices is reduced, and therefore the service life of the whole machine is prolonged, and the reliability of the whole machine is improved.

Description

technical field [0001] The invention belongs to the field of thermal management of inverter power modules, and in particular relates to a driving method and system for improving reliability of SiC inverters. Background technique [0002] Compared with traditional silicon-based devices, the main advantages of silicon carbide (SiC) power devices are high operating temperature, low on-resistance, and faster switching speed. The use of SiC power devices can effectively reduce the loss and heat dissipation requirements of the inverter, improve power density and efficiency, and can be widely used in new energy, motor drives and electric vehicles. [0003] The reliability of power devices is an important indicator of inverters. Existing research shows that one of the most important causes of failure of SiC power devices is overheating failure. The higher the average junction temperature and the larger the junction temperature fluctuation, the faster the aging speed of SiC power de...

AI Technical Summary

Problems solved by technology

[0007] 1) The heat dissipation condition control method cannot be applied to passive heat dissipation systems or uncontrollable heat dissipation systems, and cannot independently control the junction temperature of each power device

[0008] 2) The variable switching frequency method can only change the switching loss of a single-phase bridge arm. If only one power device is adjusted by variable switching frequency, the bridge arm will appear through phenomenon

[0009] 3) The dynamic voltage regulation method is only applicable to inverter systems including DC-DC modules, and when the modulation ratio is high, the DC voltage adjustment margin is small, and it is only applicable to low modulation ratio areas

[0010] 4) The modulation strategy control method can independently control the junction temperature of each power device, but due to the need to compensate the on or off state, it will generate greater harmonic distortion (THD) than the ordinary modulation method

[0011] 5) The current limiting method can control the junction temperature of the device, but it will also limit the output power and affect the working performance of the system

[0012] 6) The gate current control method can change the switching loss of the device, but cannot adjust the conduction loss, and the flexibility is low

For example, the invention patent CN104765300A --- "Power Module Thermal Management Device and Method Based on Adaptive Adjustment of Drive Circuit" is to change the gate current of IGBT through the triode current control circuit to control the junction temperature, which does not consider the temperature of multiple power devices Unbalanced problem, only to suppress the fluctuation of junction temperature

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