29 Polymer considerations for EV | Focus E-Mobility Engineering | March/April 2024 This is especially valuable for motors that run at 800 V. Cutting the thickness of the covering from 125 μm to 50 μm increases the power density by 10%, boosting efficiency by 2% at the same temperature. The thinner coating gives a higher bending radius to fit more coils into the motor for greater power. This, however, has higher thermal requirements as the higher-power motor generates more heat, so the material can operate safely up to 250 C. Thermoplastics are also used for slot-liner insulation in rotors to replace aramid papers, which have to be inserted into the motor. Rotor sleeve Premium e-motors want higher rotation speeds for higher torque, and these traditionally use carbon fibre in epoxy as the rotor sleeve. Thermoplastic carbon-fibre tapes avoid a wet manufacturing process and can be directly wound onto the stator for high-volume production processes. Thermoplastic materials boost the range and safety of EVs, especially where high-performance polycarbonate comes into play. Components made of polycarbonate are particularly lightweight and weigh up to 50% less than those made of glass. The lighter an EV is, the better it can compensate for the usually heavy weight of the batteries. Polycarbonate also allows for seamless surfaces. This enhances aerodynamics, which then reduces energy consumption due to lower drag. This results in the battery being preserved and the range increased. Various concept vehicles have taken advantage of this material to change the way components are designed and manufactured. Charging stations Using thermoplastics rather than metal in charging stations brings several advantages. At any given time, 20-25% of the world’s charging stations are not operational, partly as a result of wear and tear, and inclement weather putting a severe strain on plastic parts, such as plugs and sockets. As well as thermal resistance, insulation and mechanical-performance retention across a range of weather conditions, the plastics used for e-motor designs. The material developer worked with a magnet wire supplier to start producing thermoplastics that could be extruded onto magnet wire, rather than using enamels. The material was designed to be extruded directly onto the copper wire in one pass on a pre-formed winding without the need for additional materials or processing to improve adhesion. Removing these steps will help reduce process complexity, and therefore manufacturing costs. The pre-formed windings for a 400 V motor typically have a coating of 40-70 microns (μm), but they require 100-170 μm for 800 V, and this is very difficult with enamel as it requires several passes with more curing cycles, which can create problems for the inner layers. This requires a careful balance of electrical and thermal performance, and the thickness of the thermoplastic can be tuned from a few microns to several hundred microns. A 125 μm coating has a 13.4 kV breakdown voltage, so it can be used up to 1200 V. Using thermoplastics for home chargers reduces weight and improves reliability (Image courtesy of Livo) Windings can now be covered n thermoplastic rather than enamel (Image courtesy of Syensqo)
RkJQdWJsaXNoZXIy MjI2Mzk4