Issue link: https://resources.mouser.com/i/1442820
On-Board Chargers Get Efficiency Jump from New Inductor Design By Bourns, Inc. | 8 | The market for electric plug-in vehicles is exploding due to their contribution to helping to improve the environment by reducing CO 2 emissions and driven by continued advancements in battery technology. Optimizing all aspects of the way these vehicles are electrically charged is critical for further growth. Maximizing the efficiency of the on-board charger (OBC) is an important factor in this regard. Responsible for the final stage of charging the battery pack, an OBC takes AC input from a charging station and converts it to direct current to charge a 350V or 650V battery. However, there are a variety of factors that can affect electric vehicle battery charging efficiency. The more electric power retained by the vehicle battery from the power grid, the greater its efficiency. Making OBCs more efficient can be helped by mitigating the power losses during charging or discharging. In particular, an essential element of the OBC design is to reduce AC losses in the Power Factor Correction (PFC) stage. Because of the OBC's system power level that connects to the electrical grid, most countries worldwide now require the inclusion of the PFC stage in an OBC. This article will highlight a methodology for reducing the AC copper loss due to flux fringing in a boost inductor designed for the PFC. Design Optimization The PFC stage of an OBC utilizes a conventional boost topology that includes an input diode bridge, a filter, and a boost inductor (Lboost), shown in the block diagram depicted in Figure 1. A key requirement is that the boost inductor maintains its inductance at peak current and does not saturate. This helps ensure that the load current waveform can be shaped and the phase maintained with the input voltage. The inductor needs to have low core and copper losses so that efficiency is maintained and excessive heat is not generated.