Product Description:

The KDA 3.3-100-3-A0I-U1 is a spindle drive released by Bosch Rexroth Indramat in the KDA Spindle Drives series. As a closed-loop power stage for high-speed machine-tool spindles, it converts rectified DC-link energy into regulated three-phase output that follows velocity commands from the numerical control. The unit provides torque control, speed regulation, and motor feedback processing for precision cutting, milling, and grinding axes. This arrangement helps the spindle maintain stable rotation during rapid acceleration and changing cutting loads. Because the control loop is closed, the drive can correct speed deviations quickly when spindle load changes during machining.

Internally, the drive operates from a bus link of 300 VDC, and its output stage is rated for 100 A of continuous current so it can power large-frame spindle motors. Thermal stability relies on a mounted heat sink blower under forced cooling, with airflow directed across the fins to remove heat from the power section. The blower uses an auxiliary supply of 115 V/50–60 Hz, so airflow can be checked without applying main power to the drive. Revision 3 hardware provides one feedback path, and the design omits a second encoder input when only one motor transducer is required.

The drive is intended for ambient temperatures from 5 to 45 °C and altitudes up to 1000 m above sea level. Its front connector provides an incremental encoder output to the CNC, while the speed command is accepted as an analog voltage for smooth ramp generation without digital quantization. This interface arrangement supports stable coordination between the drive and the control during spindle acceleration, speed holding, and controlled deceleration. The single-channel feedback layout also keeps signal routing straightforward in systems that do not use an auxiliary encoder.