A motor variable frequency driving system, comprising: a three-phase alternating-current input; a rectification module connected to the three-phase alternating-current input, the rectification module used for converting the three-phase alternating-current input into a direct current output; a thin-film capacitor arranged between output ends of the direct current output; an inverter, an input end of the inverter connected to the output end of the direct current output and an output end of the inverter connected to a three-phase alternating current motor; a vector control module connected to the inverter, the vector control module used for generating a control instruction controlling the inverter; an A/D sampling module used for collecting a direct current bus voltage of two ends of the thin-film capacitor; and a steady state processing module connected to the A/D sampling module, the steady state processing module used for carrying out steady state processing on the direct current bus voltage, and outputting a compensation parameter to the vector control module, characterized in that the vector control module further comprises: an SVPWM unit used for outputting the control instruction to the inverter; wherein the steady state processing module further comprises: a high-frequency component processing unit, an end of the high-frequency component processing unit connected to the A/D sampling module, another end of the high-frequency component processing unit connected to the SVPWM unit, the high-frequency component processing unit used for correcting the control instruction output by the SVPWM unit, wherein the high-frequency component processing unit is further arranged to extract and process the high-frequency component in the direct current bus voltage, wherein the high-frequency component is processed and input into the SVPWM unit to be displayed when the voltage is converted into modulation rate. a three-phase alternating-current input; a rectification module connected to the three-phase alternating-current input, the rectification module used for converting the three-phase alternating-current input into a direct current output; a thin-film capacitor arranged between output ends of the direct current output; an inverter, an input end of the inverter connected to the output end of the direct current output and an output end of the inverter connected to a three-phase alternating current motor; a vector control module connected to the inverter, the vector control module used for generating a control instruction controlling the inverter; an A/D sampling module used for collecting a direct current bus voltage of two ends of the thin-film capacitor; and a steady state processing module connected to the A/D sampling module, the steady state processing module used for carrying out steady state processing on the direct current bus voltage, and outputting a compensation parameter to the vector control module, characterized in that the vector control module further comprises: an SVPWM unit used for outputting the control instruction to the inverter; wherein the steady state processing module further comprises: a high-frequency component processing unit, an end of the high-frequency component processing unit connected to the A/D sampling module, another end of the high-frequency component processing unit connected to the SVPWM unit, the high-frequency component processing unit used for correcting the control instruction output by the SVPWM unit, wherein the high-frequency component processing unit is further arranged to extract and process the high-frequency component in the direct current bus voltage, wherein the high-frequency component is processed and input into the SVPWM unit to be displayed when the voltage is converted into modulation rate.