Product Description:

Bosch Rexroth Indramat built the KDA 3.1-100-3-API-U1 spindle drive for high-speed machining centers and other motion-control applications that require precise speed regulation. As part of the KDA Spindle Drives series, the unit converts a direct current bus into three-phase motor power while accepting an adjustable speed command from a supervisory CNC or PLC. Its architecture supports closed-loop operation with primary and secondary encoders, allowing spindle rotation to stay synchronized with tool paths. That feedback structure helps the control system correct speed changes caused by cutting load and maintain consistent surface finish during production.

The drive operates from a DC link voltage of 300 VDC, so the connected power supply must maintain this level to keep the inverter section within its switching range. Under continuous duty, the power stage can deliver a rated spindle current of 100 A, supporting strong torque response during acceleration or heavy cutting passes. Thermal energy is removed by a mounted heat sink blower powered from 115 V/50-60 Hz, which forces ambient air across the fins to control semiconductor temperature. The unit uses forced cooling, so airflow does not depend on spindle speed and remains consistent during low-speed operation. This cooling arrangement keeps heat removal active even when the spindle is not turning fast enough to provide useful self-ventilation.

The permissible ambient range is 5 to 45 °C, and operation is intended for installations up to 1000 m above sea level. Encoder connectivity is flexible because an incremental encoder output can send real-time position pulses to the machine controller. A second encoder input can also be used for direct spindle feedback when dual-loop regulation is required. Speed commands are provided as an analog reference, which matches the Series 3 control path and allows integration with legacy CNC systems without added protocol conversion. This input and feedback arrangement supports spindle systems that need stable speed control together with external position monitoring.