4H-silicon carbide (4H-SiC) bipolar PiN rectifiers (diodes) demonstrated ultra-high breakdown voltage (VBR <-10 kV) and extremely low reverse leakage current, and nearly temperature-independent leakage current (up to 200 °C), as compared to the well-established SiC-based Schottky barrier diodes (temperature dependent leakage current behaviour and maximum breakdown voltage 1.7 kV). Moreover, 4H-SiC PiN rectifiers benefit from the drift conductivity modulation due to the minority carrier (hole) injection process, which mitigates the high-resistance of the voltage blocking layer. Junction Termination Extension (JTE) technique further reduces the electric field crowding around the junction edge, thereby theoretical breakdown voltage can be achieved. Nevertheless, performance limiting defects such as Z1/2 and EH6/7 commonly exist in the drift layer. Additional trap levels are created in the epilayer during the Al-ion-implantation process of the PiN diodes. These traps restrict the maximum achievable performance of the PiN diodes. Therefore, identification of electrically active traps and subsequent understanding of trapping effects in the PiN rectifiers are essential. In this talk, at first, the electrically active traps in the 4H-SiC bipolar 10 kV PiN diodes identified by Deep Level Transient Fourier Spectroscopy (DLTFS) are discussed. The charge trapping induced changes in the current handling capability, on-resistance, leakage current and breakdown voltage of the 4H-SiC PiN rectifiers are presented.