Abstract : To investigate the partial discharge aging mechanism of corona-resistant polyimide materials for variable frequency motors, the electrical aging thresholds of ordinary polyimide films (100HN) and corona-resistant polyimide films (100CR) before corona aging and after 8 hours of aging with corona intensities of 10 kV/mm and 20 kV/mm were measured using the conduction current method. The results show that the electrical aging thresholds of both films decrease with increasing electrical aging intensity, and the electrical aging threshold of the corona-resistant film is consistently higher than that of the ordinary film. Within the space charge confinement current region of both films, the current growth rate of the corona-resistant film is larger, indicating the presence of more shallow traps. This result is consistent with the depolarization current test results at 170℃. These shallow traps effectively regulate the electric field distribution in the polyimide film, improving its corona resistance. Keywords : Polyimide film; Conductivity current; Electrical aging threshold; Space charge; Traps; Depolarization current 0 Introduction With the development of power electronics technology, variable frequency speed control technology, especially AC variable frequency speed control technology, has been improved and perfected, leading to the widespread application of AC variable frequency speed control motors. However, the high-frequency, high-voltage resonant voltage pulses during variable frequency speed control easily cause partial discharge in the insulation, shortening the service life of the insulation in variable frequency motors. Although polyimide materials have been widely used in the electrical and electronic industry due to their superior heat resistance, mechanical properties, and dielectric properties, the high-frequency strong pulse partial discharge in variable frequency motors limits their application. In 1994, DuPont (USA), ABB (Switzerland), and Siemens (Germany) jointly developed a corona-resistant polyimide film with a service life >100,000 hours under an AC electric field strength of 20MV/m. Its corona resistance performance is similar to that of powdered mica, solving the weakness of easy aging of variable frequency motor insulation. This paper uses the conduction current method to test the aging threshold and its changes before and after corona aging of DuPont's corona-resistant polyimide film for variable frequency motors (hereinafter referred to as corona-resistant film 100CR) and ordinary polyimide film (100HN). These results have certain reference value for exploring the corona resistance mechanism of corona-resistant materials and for the modification research of insulation materials for variable frequency motors. [b][align=center]For details, please click: Study on the Electrical Aging Characteristics of Polyimide Film for Variable Frequency Motors[/align][/b]