 Hi, I'm Jeff Halvig, Product Marketing for ST Microelectronics Power Discrete Products. I'm here to introduce an exciting new evaluation board platform for power factor correction that takes advantage of ST's latest technology and second generation silicon carbide MOSFETs and advanced STM32 control. These enable a powerful bi-directional Vienna rectifier style PFC. Let's take a look. Briefly, our agenda. First, I'll introduce the demo board in its key performances and an example application. Second, I'll describe modified Vienna rectifier topologies and the power discreet that enable their performance. I'll then look at the bi-directional system architecture and control scheme before I wrap up summarizing the ST demo board solution. The ST-DEVS-PFC-BI-DIR demonstration board is a 15 kilowatt peak power three leg T-type Vienna rectifier for bridgeless power factor correction. It's targeted for bi-directional power transfer between three phase 380 volt AC and an 800 volt DC bus and based on an optimized STM32 digital platform. It's well suited for the active front end stage and high power charging stations, industrial battery chargers and UPS. The high switching frequency of the silicon carbide MOSFETs and the multi-level structure allow for nearly 99% efficiency as well as the optimization of passive power components in terms of size and cost. Here's the typical application of an industrial charger. Multi-phase AC is converted to a high voltage DC link bus and then isolated to a DC to DC stage to charge large battery banks for industrial equipment. Nominal power can be as high as 22 kilowatts and output voltage anywhere from 400 volts to 800 volts DC depending on the battery configuration. However, considering the huge energy storage capacity of these battery banks we can also utilize them to provide energy back to the grid backward to this power path. A similar approach can be made in an electric vehicle. How do we optimize this powertrain? One of the most popular and highly efficient designs for the front end of such a powertrain is the Vienna rectifier. We can look at a couple of modified topologies of this concept and choose between trade-offs. The Type 1 allows for lower voltage ready devices but requires the additional power loss associated with a second diode drop to the capacitor bank. Type 2 eliminates this loss at the expense of requiring the devices to have double the voltage rate. Fortunately, silicon carbide diodes and MOSFETs combine high performance with the high voltage ratings required. There is some cost trade-off and the overall system benefits of efficiency versus cost is up to the designer. ST can provide optimized power diodes and MOSFETs for either choice. Here we compare the performance of both Type 1 and Type 2 Vienna rectifier topologies at 20 kilowatts against three different transistor types. IGBTs, superjunction MOSFETs, and silicon carbide MOSFETs. Silicon carbide provides the best performance while the Type 2 topology improves efficiency regardless of switching frequency or transition selection. So we've decided to pursue the Type 2 configuration in the search for the most efficient operation and to take advantage of the availability of high performance silicon carbide devices. However, we still want a bidirectional power transfer capable power stage. To do this, we'll need to extend the use of silicon carbide MOSFETs to actively replace the D2 diode socket in the Type 2 topology. The result is the bidirectional PFC system architecture seen here. It requires digital control enabled by the STM32-G474 and algorithms developed by ST's power systems lab. Let's take a closer look at the control. Grid to battery shows the control scheme for AC to DC operation as a PFC. It's based on D2 access transformation, both for controlling the current and synchronizing to the grid to a PLL. In particular, for PFC operation, the two control loops are referenced to a decoupling inner loop for current control and outer loop for output voltage control. Thanks to this decoupled control, active and reactive power can be controlled independently. The battery to grid shows the control scheme for DC to AC operation as an inverter. It's still based on two control loops using D2 access transformation. But in this case, the outer loop will control the output power into the AC side, be it a load or to the grid. The results of the demo board are fantastic, greater than .98 power factor and less than 5% THD at light load while achieving peak efficiencies and greater than 99%. And the solution highlights the full complement of the ST power analog and digital portfolios from silicon-carbide MOSFETs to power diodes with wide bandwidth op-amps, LDOs, isolated gate drivers, and of course the power of the STM32 microcontroller. Thanks for listening. For more information, please visit us at www.st.com.