To achieve the monitoring of line-end and internal coil ground insulation of the stator winding for an inverter-fed machine, an insulation monitoring method based on common-mode circuit is proposed. First, based on the common-mode equivalent model of the motor, the impedance characteristics of the common-mode circuit of the motor system at high-frequency in MHz and medium-frequency in kHz were analyzed. Then, based on the common-mode impedance characteristics, the dominant mode and path of common-mode current were analyzed. Theoretically, the relationship among the oscillation frequency of medium- and high-frequency common-mode current, the terminal ground capacitance and the internal ground capacitance of the stator winding was derived. The variational mode decomposition algorithm was used to separate the two modes of common-mode current, and the insulation degradation statuses of the line-end and internal coil of machine stator winding were monitored through high-frequency common-mode current and medium-frequency common-mode current, respectively. Experimental results show that the proposed method can sensitively reflect the slight changes in the insulation at the line-end and internal coil of machine stator winding.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |