Name: Treadmill Speed Control for an AC Induction Motor

The customer wanted their high-performance commercial treadmills to utilize the best motor technology.

Overview: In the application of treadmills, each of the runner's footfalls creates an instantaneous peak load on the treadmill's moving belt. The treadmill must maintain a smooth speed profile during these footfalls. To maintain this smooth speed profile, the AC motor speed control is required to produce high instantaneous torque with each footfall while maintaining smooth, constant speed.

The application benefit: By controlling the AC induction motor with a dedicated Variable Frequency Drive (VFD) designed for treadmills, a low-cost, smooth performance is achieved. The AC motor is immune to brush wear, demagnetization, and run away, and costs less than a DC motor.

The customer's product: The customer's product is a large commercial treadmill designed to be used 24/7 in health facilities.

The customer's present solution: The customer's existing treadmills are supplied with costly speed controllers using a servo-type inverter. The customer's request was for a low-cost VFD to replace the high-cost servo providing the same or improved performance.

The customer selected the KBVF-26D Adjustable Frequency Drive (AFD) for high starting torque, and smooth, whisper-quiet operation. KB brought the customer's existing treadmill into its engineering lab for evaluation. The AC motor parameters were measured across the range of operation from low to high speeds with light and heavy loads.

KB's capabilities for solving the problem: For the Variable Frequency Drive, it's the KBVF series. This series incorporates the powerful, second-generation, micro-controller that is programmable for custom OEM applications using software that has proprietary motor monitoring capabilities. KB's engineering staff has a reputation of working directly with customer applications to reach satisfactory solutions.

The KB solution: The objective was to produce smooth operation and high torque using our tried and true KBVF-26D with customized fuzzy-logic software. The KBVF software was designed to include the advanced, fuzzy-logic algorithms based on the measured motor parameters obtained through extensive in-house testing.

The results: Using the KBVF-26D TM, the treadmill had smooth operation with high torque throughout the speed range.

Customer's strategic advantage: The customer got exactly what he wanted - no more, no less - with major performance enhancement, achieved through custom algorithms based on motor parameters and advanced circuit design, resulting in a major advantage over the competition.

A Win-Win solution for both the customer and KB.