The 24V, 300W, BLDC Kollmorgen motor integrated controller

Paul Rako, Technical Editor - September 22, 2011

The 24V, 300W, BLDC Kollmorgen motor with integrated controller image 1

Kollmorgen, a subsidiary of Danaher Corp, manufactures the 24V, 300W BLDC (brushless-dc) motor in India. A true BLDC motor, it has Hall-effect sensors that feed back the rotor position to the integrated controller. This motor, whose part number begins with CTI, is not a stepper motor, such as the CTM and CTP lines that Kollmorgen also sells; it has significant performance advantages over stepper motors. For example, its rotor incorporates closed-loop feedback and permanent magnets. Two pigtail leads come off the motor, and you feed 24V power to the thicker wires. The motor’s thin harness allows you to connect a potentiometer for speed control and a switch to disable the motor. Kollmorgen most likely intended the motor for use in electric scooters and wheelchairs. Although the integrated controller eases installation, the heat it produces affects the electrolytic capacitors, reducing reliability.

The 24V, 300W, BLDC Kollmorgen motor with integrated controller image 2

1. This 0.031-in. FR (flame-retardant)-4 board houses an arc-shaped 0.042-in. FR-4 PCB (printed-circuit board) that holds the three Hall-effect sensors.

2. The rotor is a steel shell with an outer black ring made of permanent-magnet material.

3. The rear bell of the motor holds the BLDC controller. The two large electrolytic capacitors provide a low-impedance dc bus, preventing large switching spikes due to wiring inductance. The toroidal inductor might reduce heat-producing harmonics to the windings. A potting compound helps the motor to resist vibration and conducts heat from the components.

The 24V, 300W, BLDC Kollmorgen motor with integrated controller image 3

The 24V, 300W, BLDC Kollmorgen motor with integrated controller image 3

4. One of the pliers in the $6 Harbor Freight 96512 snap-ring pliers set eases disassembly.

5. Kollmorgen engineers used insulated tape to protect the windings from the Hall-effect sensor’s PCB solder tails. They also placed glass-reinforced tape over the switching inductor in the controller.

6. An O ring seals the motor’s end bell. The fit of the parts exhibits tightly held machining tolerances, even though the end bell does not hold a rotor bearing.