A High-speed Gate Driver with Printed-circuit-board-embedded Rogowski Switch-current Sensor for a 10 kV , 240 A, SiC MOSFET Module
As a result of the booming technology of wide-bandgap (WBG) semiconductor devices and packaging, silicon carbide (SiC) MOSFETs have demonstrated their superior performance to silicon (Si) insulated-gate bipolar transistors (IGBTs). Wolfspeed has developed a 10 kV, 240 A SiC MOSFET, module XHV-6, which uses their 3rd generation 10 kV, 350 mΩ SiC MOSFETs with an improved package layout. This device is suitable to construct converters such as a 6.7 kV dc, 3.3 kV ac motor drive, by using a simple three-phase two-level topology. For the XHV-6 module, three submodules that contain eighteen 10 kV, 350 mΩ SiC MOSFET dies need to be driven simultaneously. The driving current magnitude, driving signal synchronization, driving loop parasitics, and common-mode noises become big challenges. A gate driver can provide quick, reliable, and configurable protections, as well as advanced switch-current signal sensing, digital data processing, and active gate controllability; all of which define a smart gate driver. A prototype gate driver is shown on Fig. 1. A well-planned gate driver architecture design is able to keep common-mode (CM) noise current away from sensitive components. This is even more critical for a smart gate driver, as a large amount of analog and digital signals are processed on the board. A field-programmable gate array (FPGA) manages gate driver IC programming, RSCS reset, analog/digital conversion (ADC), and communication to other units. External current boosters are designed to supply al-most 90 A peak current to sustain the fastest switching transient and to fully enable the benefits of the SIC MOSFET device. A current booster solution with nine paralleled bipolar junction tran-sistors (BJTs) has been proposed and designed. A Rogowski switch-current sensor (RSCS) has been proposed to work effectively together with the SiC MOSFET modules. The high bandwidth, wide measurement range, good accuracy, and solid signal isolation make it an excellent short-circuit current detector and current control for SiC devices. Fig. 2 shows the 6 kV double pulse test result at 120 A, achieving 50 V/ns transient switching.