MOTOR VARIABLE FREQUENCY DRIVING SYSTEM AND MULTI-SPLIT CENTRAL AIR CONDITIONER

Disclosed are a motor variable frequency driving system and a multi-split central air conditioner. The motor variable frequency driving system comprises: a three-phase alternating-current input (102), a rectification module (104), a thin-film capacitor (106), an inverter (108), a vector control module (110), an A/D sampling module (112) and a steady state processing module (114). The rectification module (104) is connected to the three-phase alternating-current input (102); the thin-film capacitor (106) is arranged between output ends of a direct current output; an input end of the inverter (108) is connected to an output end of the direct current output; an output end of the inverter (108) is connected to a three-phase alternating current motor; the vector control module (110) is connected to the inverter (108); the A/D sampling module (112) is used for collecting direct current bus voltages of two ends of the thin-film capacitor (106); and the steady state processing module is connected to the A/D sampling module (112).