A rotor position detection strategy based on virtual neutral point was proposed to realize position sensorless control of BLDC motor. Through the three-phase terminal voltage with the same value of three resistances star connection to construct a virtual neutral point,the relationship between the virtual neutral point voltage and commutation time of BLDC motor was analyzed. A conclusion was drawed that the moment when the virtual neutral point voltage through the DC bus midpoint is the zero-crossing time of the back electromotive force (BEMF),and the operation of the motor in each state,the effectiveness of zero-crossing signal of BEMF was further analyzed. The scheme was further verified by experiments,and the output of zero-crossing signal was realized by comparator. Compared with the conventional terminal voltage detection method,the system reduced two comparison detection circuits and has no phase shift. Experimental results show that the position of zero-crossing signal can be accurately determined by using this strategy,and the phase error caused by traditional BEMF method can be avoided.
| 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 |