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Phase Current Reconstruction, DC Link Voltage and Rds_on Measurement Using Sensors Integrated on Gate Drivers for SiC MOSFET
Year: 2023 | Author: Vladimir Mitrovic | Paper: H5.10
Fig.1. Enhanced Gate Driver with IDS, VDSON and VDSOFF sensing
IDS measures the drain-source current of both switching devices in the phase leg using PCB embedded Rogowski coil (Fig. 1). Output of Rogowski coil must be integrated and then signal conditioned before passing to ADC (analog to digital converter). Fig. 2 shows comparison between commercial current sensor and current reconstructed from the Rogowski coil. Reconstructed current reading is further digitally filtered and it matches the commercial sensor very well.
VDSOFF measures drain-source voltage of a switch in the phase leg when switch is in off state. It uses a high voltage divider to reduce voltage level before sending it to signal conditioner. Voltage in range of ±3 V is passed to ADC through signal conditioner. VDSOFF sensing could be used for dc link capacitor voltage balancing.
VDSON measures drain-source voltage of a switch in the phase leg when switch is in on state. The two-diode method is used for precise measurement. The signal is conditioned and sent to ADC. VDSON is used in combination with IVDS for RVDSON calculation, which could be further used for health estimation of switching device.
Digital data from both switches, for all sensors is combined and packed into the gate driver and sent to the controller using previously designed communication protocol.
Some benefits of gate drivers with integrated sensors and communication are hardware simplification, enabling of distributed control and increased power density.
Fig. 2. Comparison between commercial current sensor measuring output current and output current reconstruction reading from GD integrated sensor
