Mitigating Inrush Currents to Improve Power Integrity in Electric Vehicle Systems

Electric Vehicles (EVs) represent a significant leap in mobility technology. Battery systems in EVs serve as the powerhouse, providing the necessary constant power for all electronic devices within the vehicle. To mitigate voltage spikes, sudden surges, ripples in power rail, input capacitor filters are employed. When an electronic device initially turns ON, a sudden surge of current into the capacitor filter circuit may result in voltage dip/fluctuation, which may damage components or compromise the power supply's overall stability. Engineers include inrush current limiting mechanisms to reduce this risk. If a resistance is included in the charging path, that can limit the inrush current but it poses constant power loss. Here, two intelligent inrush current limiters are discussed: 1) An inrush current limiter using relay: in this solution, when the capacitor is sufficiently charged, relay shorts the current limiting thermistor to reduce power dissipation. 2) A power MOSFET enabled active inrush current limiter, which exploits quick switching speed, low switching loss, straightforward gate drive, and low ON resistance of MOSFET to limit inrush current actively. Simple electronic components are used in the construction of the monitoring and control circuits, which lowers the cost, complexity, and area. Simulation results prove the effectiveness of proposed methods.