The series of flameproof variable frequency speed-regulating three-phase asynchronous motors are suitable for use as power drag motors in underground coal mines (non-mining and excavation work areas) and factory operation sites containing explosive gas mixtures. The motors are matched with variable frequency devices and have the advantages of good speed regulation performance, energy saving, large temperature rise margin, long service life, good performance, low noise, advanced flameproof structure, high reliability, and convenient use and maintenance. The speed is adjusted by changing the frequency. The motor has a wide speed regulation range. Under open-loop U/ control conditions, it can achieve constant torque speed regulation from 3 to 50Hz and constant power speed regulation from 50 to 100Hz. Under vector control conditions, the speed regulation range can be further expanded. It has strong overload capacity and can withstand an overload of 160% of the rated torque for 1 minute. The YBBP variable frequency speed regulation three-phase asynchronous motor is applied in industries such as light industry, textile, chemical engineering, petroleum, metallurgy, machine tools, and water pumps. The YBBP series motors have an independent cooling fan added to the electrical rear part. The installation dimensions of the YBBP series flameproof variable frequency speed-regulating three-phase asynchronous motors are the same as those of the YB2 series motors. This series of motors complies with the provisions of the national standards GB3836.1 “Explosive Atmospheres – Part 1: Equipment – General Requirements” and GB3836.2 “Explosive Atmospheres – Part 2: Equipment Protected by Flameproof Enclosures’ d ‘”. The electrical performance complies with the provisions of JB/T 11201.1-2011 “Technical Conditions for Flameproof Variable Frequency Speed Control Three-phase Asynchronous Motors – Part 1 :YBBP Series Flameproof Variable Frequency Speed Control Three-phase Asynchronous Motors (Frame sizes 80-355)”. The power ratings and installation dimensions of this series of motors comply with the standards of the International Electrotechnical Commission (IEC).