[ Abstract ] This paper analyzes the causes of problems such as asynchronous operation of the trolley motor and the design scheme of the frequency converter in the multi-functional overhead crane drive system of an electrolytic plant, and introduces improvement measures for the trolley and carriage drive system. [ Keywords ] Frequency converter; drive; torsion; master-slave control; speed feedback; quasi-synchronization 0 Overview The multi-functional overhead crane in aluminum electrolysis is the main production equipment in electrolytic cell operation. The quality of the crane drive system directly affects the equipment condition. In the 1990s, the First Electrolysis Plant of Qinghai Branch of China Aluminum Corporation upgraded the drive system of the multi-functional overhead crane's trolley and carriage, adopting Et Bensanken MF series frequency converters. After years of use, it was found that the frequency conversion upgrade still had many problems. Due to factors such as uneven track joints and the use of a "one-to-two" frequency converter for the carriage drive, torsion occurred in the carriage movement, affecting the main beam and end beam of the overhead crane. [b]1 Problems with the Drive System 1.1 Twisting Phenomenon During Trolley Movement 1.1.1 Causes of Twisting[/b] The multi-functional overhead crane's trolley drive system uses a "one-to-two" control method with a frequency converter, lacking a synchronous control link for the two motors. When issues arise such as inconsistent track straightness or unevenness at track joints, the resistance torque generated by the large wheels on both sides of the aluminum electrolysis multi-functional overhead crane is unequal, causing different speeds of the two motors and resulting in twisting during trolley movement. 1.1.2 Consequences of Crane Twisting ① When the two motors operate asynchronously, the slower motor may stall, causing it to overheat, burn out the frequency converter, and increase maintenance costs. ② Asynchronous operation of the two trolley motors, resulting in trolley movement twisting, is also one of the causes of cracking in the multi-functional overhead crane's main beam and end beams. [b][align=center]For more details, please click: Improvement of the Drive System for Aluminum Electrolysis Multi-functional Overhead Crane[/align][/b]