Nano Micro new optical coupling compatible intelligent isolation single tube driver

     Nanocore micro single channel intelligent isolated grid driver NSi68515, designed for driving SiC MOSFET, IGBT up to 2121V DC bus voltage, can be widely used in industrial frequency converter, servo, robot, air conditioning compressor, new energy vehicle main drive, photovoltaic inverter, energy storage, UPS, high power supply and other fields. The input mode of NSi68515 is compatible with the optocoupler-input, and the input end and output end adopt the double capacitance enhanced isolation technology. Based on the nanocore microadaptive OOK coding technology, the minimum common mode transient immunity (CMTI) of 150kV/μs is supported, which improves the system robustness.

     The common industry with protection of the optocoupler isolation drive IC, CMTI generally in 35KV/us. With the increase of switching frequency and busbar voltage of the system, and the popularization of SiC mosFETs, dv/dt of the system increases sharply, which puts forward higher requirements on the anti-jamming capability (CMTI) of the isolated drive. If the CMTI of the isolated drive IC is only 35KV/us, it is obviously difficult to meet the requirements of the system. NSi68515 CMTI is larger than 150KV/us, which can effectively improve the anti-interference ability of the system. Static CMTI and dynamic CMTI were tested on NSi68515, and the results showed that the PASS was 218KV/us. Under the same test conditions, the common optical coupling isolation drive has failed at about 30KV/us.

     When IGBT and SiC MOSFETs are open normally, they work in the saturated area. But when IGBT and SiC MOSFET in the opening process, the occurrence of flow or short circuit of the upper and lower tubes, the current will increase sharply, will exit the saturation area, VCE also increases, if not timely off IGBT and SiC MOSFET, it will lead to pipe damage or service life becomes shorter. NSi68515 detects the VCE voltage of the pipe through the DESAT pin to judge the short circuit and overcurrent of the pipe. When the abnormal pipe is detected, the pipe can be quickly shut off to prevent the pipe damage. In addition, the NSi68515 DESAT pin is also filtered inside to prevent the system from triggering by mistake.