Name: Chairlift Motion Controller

The customer wanted their chairlift's logic, interface, and DC motor speed controller integrated into a low-cost, customized controller.

Overview: The customer manufactures chairlifts for elderly and wheelchair-bound persons to convey them up and down stairs. The chairlift system includes the motor, motor speed controller, and up/down limit switches; remote direction controls; safety interlocks; and guide rails.

Application benefit: By integrating all of the logic into the Drive control's customized software, we were able to lower costs and increase reliability.

The customer's product: The customer's product is a chairlift with the motor, speed control, and logic control enclosed under the chair seat. The chair runs on rails bolted to the user's stairway. Power is connected to the chair through a drag cable, plugged into a wall outlet, at the top or bottom of the rail.

The customer's present solution: The customer's chairlift included an off-the-shelf DC PWM motor speed controller, remote control circuit board, power supply, and interface terminal blocks with discrete wire interconnect. The customer's request was to integrate all of the control logic into a low-cost, DC motor speed control.

KB installed the customer's chairlift system on the engineering lab's stairway. Our engineering team was able to determine the logic sequence and performance of the existing system and develop the specifications.

KB's capabilities for solving the problem: It's the KBVF Variable Frequency Drive series customized into a DC PWM reversing drive with dynamic braking. This series incorporates the powerful, second-generation, micro-controller that is programmable for custom OEM applications using software with 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 integrate all of the control logic and interface into the KBVF. The KBVF hardware was modified into the DC PWM motor speed control and the fifth IGBT was used to control the motor braking.

A custom interface circuit board included remote control circuitry integration and provided connection and interface to the control and limit switches. The software was designed to control the H bridge for DC output to power the chairlift DC motor. Additionally, the software was designed to incorporate the complete chairlift sequencing and interlock logic, and the remote control IR sensor serial commands were decoded.

The results: Using the KBVF-24D with a custom input/output circuit board, the chairlift could be controlled by one hardware module integrating all of the chairlift functions.

Customer's strategic advantage: The customer got exactly what he wanted - no more, no less - with logic performance enhancement, reliability improvement, cost reduction, and a competitive edge.

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