505: Danfoss Stepper Motor Lifecycle Fixture

Danfoss Turbocor designs high-efficiency compressors that help heat or cool large buildings. They tasked us with improving their testing procedure for an important stepper motor in their compressors. This stepper motor controls air entering the compressor by opening and closing small fins, similar to an air conditioning vent. Danfoss Turbocor evaluates the motor’s lifecycle to assess quality, reliability and overall compressor performance. They lacked an official testing device, so our project focused on building one.

We aimed to design a high-quality stepper motor testing fixture and user interface with multiple requirements. The fixture needed to perform tests for months, requiring reliable materials and electronics. It needed a user-friendly design with a simple interface and visual indicators like LEDs showing motor failure. The fixture also needed to follow Danfoss Turbocor’s safety standards for machines with moving parts.

The result was the H-Frame, designed to securely hold and apply constant resistance torque to the stepper motor over the lifecycle test. Made of aluminum with stainless steel bolts, it features a user interface with screen and control knob similar to car displays. Users can start tests, input parameters like speed and direction and review results. A magnetic sensor tracks rotations and detects failure to determine the motor’s lifecycle. The testing procedure measures the motor’s limits, ensuring Danfoss Turbocor stepper motors perform as intended.