Patent ID: 8152082

Claim:
A variable frequency controlling system of a shredder, said variable frequency controlling system comprising: a thickness sensor for detecting a thickness of an article fed into said shredder, and issuing a thickness-detecting signal according to said thickness of said article; a speed-variable motor operated at a first rotating speed or a second rotating speed, thereby providing motive power to said shredder; a controlling module electrically connected to said speed-variable motor and said thickness sensor, and including a first look-up table, wherein when said thickness-detecting signal is received by said controlling module, a motor frequency value and a motor voltage value corresponding to said thickness-detecting signal are searched from said first look-up table and outputted from said controlling module to said speed-variable motor, so that said speed-variable motor is controlled to be operated at said first rotating speed or said second rotating speed according to said motor frequency value and said motor voltage value; and a mode-switching element, which is manipulated to switch said shredder between a first mode and a second mode, wherein said controlling module includes a second look-up table corresponding to said second mode, and said second look-up table includes a preset motor frequency value and a preset motor voltage value corresponding to said thickness-detecting signal, wherein if said shredder is switched to said second mode, said controlling module outputs said preset motor frequency value and said preset motor voltage value to said speed-variable motor by referring to said second look-up table, so that said speed-variable motor is operated at a preset motor rotating speed.