Product Description:

The VAC1-D6-A is an AC spindle drive module manufactured by Okuma for use in high-speed machine-tool spindles within the VAC Spindle Drives series. By converting fixed mains power into a controlled variable-frequency output, the drive allows the CNC controller to regulate spindle speed and torque during metal cutting, drilling, and grinding cycles. It serves as the power interface between the motion processor and the spindle motor while managing current loops and protecting the motor windings during rapid acceleration and deceleration.

The drive has a rated capacity of 6 kW, so it can support continuous spindle operation within that power level. A 16-bit processor handles the arithmetic used for vector control, allowing finer resolution when output frequency is adjusted. Speed reference enters the unit through an analog interface, so a ±10 V signal from the CNC sets the commanded spindle speed. Position feedback arrives as differential sine waves with an encoder A/B amplitude of 3 Vpp, helping the control circuit maintain stable phase tracking in electrically noisy cabinets. Four main line fuses, F1 through F4, are rated at 5 A each, and the IOCR and IOCS protection thresholds trip at 250 mV to detect overcurrent in the inverter legs.

Power conversion uses 12 base-circuit transistors arranged in a three-phase bridge, with junction temperature monitoring handled by the VAC-BOARD-A control PCB. The logic section requires a minimum board revision of E4809-045-084-D for proper hardware compatibility. The DC link and switching stage are separated by 6 power fuses, while auxiliary fuses F5 and F6 are rated at 0.5 A to protect low-power control circuits. This layout helps isolate faults quickly and reduces the chance of damage spreading from the power stage to the control section.