industry  SiC electronics


that the SiC combination excels over a wide temperature range (see Figure 4). In comparison, when silicon IGBTs are pushed beyond 175 °C their leakage current rockets.


We have also investigated the switching performance of SJTs and silicon IGBTs using an inductively clamped, double-pulse switching setup. This involves using our 1200 V/ 7A Schottky diode and silicon IGBT co-packs as free-wheeling diodes in the switching test circuit. Gate and source terminals of the silicon IGBT co-pack were tied together (VGS


= 0 V) to prevent IGBT conduction during dynamic testing. Measurements demonstrated the superiority of SiC devices over a wide temperatures range


Figure 4: Comparison of leakage


currents of SiC SJT and silicon IGBTs as a function of temperature


(see Figure 5). At up to 250 °C, the SiC SJTs displayed temperature-independent drain-current rise and fall times as short as 12 ns and 14 ns, respectively, for switching at 800 V and 7 A. These ultra-short switching times enabled the pair of SiC devices to deliver switching losses that are lower than the all-silicon configurations and those based on a silicon IGBT and a SiC free-wheeling diode.


It is possible to determine the contributions to the power loss of all these devices by considering dynamic and static characteristics for a 100 kHz switching frequency (see Figure 6). At 250 °C, the gate drive, conduction and switching losses of the SJT are 5.25 W, 26.65 W and 20 W, respectively. Note that although the gate driver loss of the SJT is higher than that of the silicon IGBT, its contribution to the overall losses is insignificant. These measurements also take into account the higher conduction losses of the SJT operating at 250 °C.


The measurements show that it is possible to trim overall switching losses by more than 30 percent by simply replacing a silicon fast-recovery epitaxial diode with a SiC Schottky diode for the free-wheeling diode. However, when an all-SiC line-up is employed in the place of silicon IGBTs and pin diodes, power loss reduction is cut by more than 50 percent. These tremendous energy savings show that SiC is well on the way to unlocking its potential at high temperatures.


We are now allowing key potential customers to evaluate the performance of our SJTs and high- temperature Schottky barriers for themselves, while we simultaneously validate our products. These products will expand our portfolio, which also includes SiC Schottky barrier diodes with a more conventional operating range and SiC thyristors.


© 2012 Angel Business Communications. Permission required.


Figure 5: Comparisons of ‘turn-off’and ‘turn-on’switching energies for SiC SJT and silicon IGBTs at various operating temperatures.“Si TFS + SiC FWD”represents a silicon trench field stop IGBT as the device under test (DUT) and the SiC Schottky diode as free-wheeling diode.In the case of “Si TFS + Si TFS”,the silicon TFS IGBT is the DUT,and the silicon TFS IGBT co-pack is the free-wheeling diode.A commercially available IGBT gate driver with an output voltage swing from -8 V to 15 V is used for driving all the devices.While driving the SiC SJT,a 100nF dynamic capacitor connected in parallel with the gate resistor generated high initial dynamic gate currents of 4.5 A and -1 A during turn-on and turn-off switching,respectively,while maintaining a constant gate current of 0.52 A during its turn-on pulse.These large initial dynamic gate currents charge/discharge the device input capacitance rapidly,yielding a faster switching performance.The testing process also involved a 1 µF charging capacitor,a 150 µH inductor,22 Ω gate resistor and a supply voltage of 800 V


36 www.compoundsemiconductor.net March 2012


Figure 6: Overall loss comparison of SJT and silicon IGBTs at their maximum operating temperature.The results are given for a 100 kHz switching frequency


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136