Tandem control system for machine tool and method for controlling same

A tandem control system for machine tool, comprising:

• a numerical control unit;
• a main operation unit;
• a PLC performing a control command through communication with the numerical control unit or the main operation unit;
• a servo drive having a notch filter unit and performing the control command of the PLC;
• a servo motor unit driven by controlling the servo drive;
• and
• a power conversion unit electrically connected to the servo motor unit and the servo drive to apply current to the servo motor unit,
• wherein the servo drive performs resonance suppression according to an operation of the servo motor by adjusting an application state of the current applied to the power conversion unit according to a change in notch filter coefficient of the notch filter unit, which is calculated in real time,
• wherein the servo drive includes:
• an output unit outputting an operation speed signal of the servo motor unit and a torque signal transferred to the power conversion unit, and
• a notch filter control unit calculating the notch filter coefficient of the notch filter unit in real time, and controlling whether to apply the current transferred to the power conversion unit by the calculated notch filter coefficient,
• wherein the servo motor unit includes:
• a first servo motor and a second servo motor connected in parallel to each other, and
• according to the real-time change of the notch filter coefficient of the notch filter unit, resonance suppression which occurs during tandem control of the first servo motor and the second servo motor is controlled by adjusting, in real time, whether the current transferred to the first servo motor and the second servo motor, respectively is applied through the power conversion unit,
• wherein the notch filter control unit includes:
• a memory unit storing information for the tandem control for suppressing the resonance generated during the parallel operation of the first servo motor and the second servo motor,
• an operating unit calculating the notch filter coefficient of the notch filter unit through the information stored in the memory unit, and
• a command unit performing the resonance suppression through the tandem control in real time by blocking the current applied to the power conversion unit by the notch filter unit through a resonance attenuation command according to a result of the operating unit,
• wherein the memory unit includes:
• a basic data storage unit storing information on a maximum value of a linkage magnetic flux by an equivalent permanent magnet, an angular speed at an operation point, a DC gain of the notch filter unit, an inductance of a winding of a stator of the servo motor unit, a pole constant of the servo motor unit, state winding resistance of the servo motor unit, and a rotator inertia moment of a circuit thermo motor unit,
• a feedback data storage unit storing location and speed feedback information of the first servo motor generated when operating the first servo motor in parallel to the second servo motor and storing the location and speed feedback information of the second servo motor generated when operating the second servo motor in parallel to the first servo motor, and
• a real-time data storage unit storing a real-time notch filter coefficient of the notch filter unit calculated by the operating unit and a current resonance attenuation command output from the command unit.