Patent ID: 8764426

Claim:
An electromotive injection molding machine comprising a power supplying apparatus that supplies power to servo amplifiers through a DC circuit, the servo amplifiers driving servo motors provided to components of the electromotive injection molding machine, the components including a screw, a mold opening/shutting device and a molded product ejecting device, wherein the power supplying apparatus comprises: an AC/DC converter, which includes a PWM converter, and which converts a three-phase AC voltage to supply a DC voltage to the DC circuit; and a first power storage circuit, which is connected to the DC circuit, and which includes at least first and second loop circuits, wherein the first loop circuit is a circuit in which the DC circuit, a coil, a first switch circuit and a capacitor are connected in series between a positive terminal and a negative terminal, wherein the second loop circuit is a circuit in which the coil and a second switch circuit are connected in series between the positive terminal and the negative terminal, wherein the first switch circuit includes a first diode and a first transistor, which are connected in parallel with each other, wherein the first diode is provided to supply current in a direction from the positive terminal to the negative terminal, and wherein the first transistor is provided to supply current in a direction from the negative terminal to the positive terminal when the first transistor is turned to be ON, and wherein the second switch circuit includes a second diode and a second transistor, which are connected in parallel with each other, wherein the second diode is provided to supply current in a direction from the negative terminal to the positive terminal, and wherein the second transistor is provided to supply current in a direction from the positive terminal to the negative terminal when the second transistor is turned to be ON, wherein the electromotive injection molding machine comprises a controller that is configured to: in a process of a molding cycle except for an injection process, control ON/OFF of the second transistor to store predetermined charges in the capacitor and to store power in the first power storage circuit; and in the injection process, control the AC/DC converter to: obtain a temporary target current, which is a temporary target value for direct current of the AC/DC converter, from a difference voltage between a target voltage of the DC voltage and an actually measured voltage; obtain a target current by removing a high frequency component exceeding a frequency having a predetermined threshold from the temporary target current; and control a direct current supplied from the AC/DC converter to become the target current, and wherein in the injection process, when supplying the power stored in the first power storage circuit to the DC circuit by controlling ON/OFF of the first transistor, a target coil current for controlling current flowing through the coil is the high frequency component of the temporary target current.