Issue link: https://resources.mouser.com/i/1510154
38 EV and Connected Transportation Avoiding Arc Tracking Damage With high-voltage sources, carbon tracks may form on the surface of polymeric insulators, causing the insulator to lose its dielectric properties and become an electric transmitter instead. Electrical arcing can then occur across the conductive path, resulting in power loss with a high probability of ignition. Once again, proper insulation materials must be used to avoid this problem. Handling the Effects of Environment on Inception and Extinction Voltages Partial discharges can occur when two parts of a circuit that are not adequately protected from each other are subjected to high voltage differences. Voltage differences become more extreme as altitude, temperature, and frequency increase. Inception voltage is when the corona effect starts; extinction voltage is when it ends. Consequently, electrical systems must be protected to minimize critical voltage differentials encountered within the operating environment. Handling High Network Operating Voltages (>3kV DC) Electric propulsion motors and higher network operating voltages impose significant demands on relays and contactors used for propulsion motor power switching, battery charging management, comfort heating for passengers, and other auxiliary functions. High-voltage relays and contactors can be specified to meet peak load capacity, operating temperature, coil efficiency, short-circuit protection, breaking capacity, and other critical requirements. Negating Skin Effect When determining proper shielding and filtering for electromagnetic compatibility (EMC), designers must account for skin effects—the tendency of an alternating current (AC) to flow close to the surface of a conductor. Skin effect is the result of eddy currents induced by the changing magnetic fields of alternating current and, therefore, is a factor in nearly every AC design. Printed circuit board (PCB) traces and other aspects of AC power circuits can be designed to negate skin effect, but expert planning is required. Managing Size and Weight Constraints Components used in high-power electrical energy storage and management can add weight and volume. High-efficiency relays and contactors are available from TE to handle higher voltage and amperage within a compact footprint, helping meet the demanding size, weight, and power (SWaP) requirements of electric aircraft. TE applies the same approach to minimize SWaP solutions for cables, terminations, and connectors. Managing Thermal Issues Dissipating heat, especially in composite structures can present challenges. When wires and relays are exposed to higher temperatures, pick-up voltage (V PI ) and coil resistance (R C ) are affected. To ensure stability, it is important to determine the steady-state characteristics for the temperature and voltage combination of a direct current (DC) relay's operating conditions. This is also true for AC applications, although their V PI exhibits less variation over temperature than with DC relays. Handling Power Management High-frequency switching enables rapid bus transfer in the event of power loss. There are valuable differences between hybrid electromechanical and solid-state power-switching technologies that TE experts can evaluate for a given application. Higher Demand for Reliability The number of takeoffs and landings will increase significantly in AAM applications. This puts additional stress on the electrical interconnect system. TE strives to understand these new reliability levels and provide the appropriate product recommendations. Solutions Today's AAM projects benefit from the cross-discipline development of power management solutions introduced by TE for the automotive, aerospace, energy, and rail sectors. TE is working with industry standards groups— such as SAE International—that are starting to deal with the challenges imposed by higher power and voltage levels. And TE experts are directly involved in Voice of Customer (VOC) initiatives to provide insights into solving aircraft power problems at the sub-system and component level. For designers, a "follow-the-wire" methodology uncovers critical factors in selecting the appropriate high-power and voltage solutions. TE supplies these needs with well-known families of power- management products: