Corona-resistant polyimide composite film sintered copper flat wire

The rapid development of rail transportation has placed higher demands on the performance of high-power traction locomotive motors. Under high voltage, weak insulation points in the motor are prone to corona discharge, which imposes stricter requirements on the performance of polyimide film-wrapped copper flat wires—a key material in motor insulation structures. Corona discharge poses significant risks to the inter-turn insulation of variable-frequency motors. The thermal effects, ozone, and nitrogen oxides generated by corona discharge can cause partial discharges and space charge accumulation within the insulation structure of variable-frequency motors, leading to localized temperature increases in the inter-turn insulation and accelerated insulation aging. This directly affects the lifespan and normal operation of variable-frequency motors. During the manufacturing process of sintered polyimide film electromagnetic wires, if air on the material surface is not effectively expelled, the bonding strength between the film and the wire core, as well as between the film layers, is reduced. These weak insulation points can easily trigger electrical discharges during the operation of traction motors, thereby shortening the motor's operational life. Research has shown that the primary factors affecting the electrical endurance of polyimide film-wrapped copper flat wires are the sintering temperature, wrapping tension, and infrared radiation furnace temperature. Under appropriate processing conditions, the electrical endurance of polyimide film-wrapped copper flat wires can be optimized. Sintering temperature, wrapping tension, and infrared radiation furnace temperature are critical factors influencing the electrical performance of these wires. With a sintering temperature of 230°C, wrapping tension of 8N, and infrared radiation furnace temperature of 450°C, the electrical endurance of polyimide film-wrapped copper flat wires reaches an optimal level.