High-speed encoders for motor test benches

Accurate detection of the position and speed of drives.

The constantly increasing speeds of vehicle drives are forcing manufacturers of motor test benches to upgrade the measurement technology of their systems. Incremental and absolute encoders from Hengstler are ideally suited for this purpose: they detect both the position and the speed of motors with absolute accuracy, even at 25,000 revolutions per minute.

The current boom in electromobility has been accompanied by continuous increases in the speeds of the drives. The reason is simple: high-speed drives are more compact and lighter than conventional electric motors. As a direct result, this reduces the vehicles' energy consumption and increases their range – a crucial selling point for the industry.

However, these higher speed drives also require correspondingly powerful test benches. Conventional encoders can no longer measure the position of the drive shaft and the speed of the drive accurately enough at more than 12,000 min-1.

Encoders from Hengstler, on the other hand, have no difficulty coping with this task. The ACURO AC58-I absolute encoder, for example, is ideally suited for use on motor test benches because it offers a high resolution of up to 29 bits (multi-turn) as well as an integrated incremental encoder with up to 2,048 lines. With an accuracy of 35" and a repeat accuracy of 10", the encoder is predestined for all applications in which exact positioning with speed feedback is required. The ACURO AC58-I can be used both on the motor under test and on the drive motor of the test bench. Thanks to its short installation depth of only 50 mm, the ACURO AC58-I also fits very well in the tight installation spaces found in motor test benches.

The absolute encoder's data transmission system uses optionally an HTL or a TTL incremental output. The values measured can be transmitted to a control system for evaluation through an SSI interface. For test bench applications with lower speeds, Hengstler offers the ICURO RI58D incremental encoder. That encoder has a master gauge element with 10,000 steps (direct read) and can output up to 40,000 steps, thanks to the True Read technology developed by Hengstler. On request, Hengstler also modifies its encoders to meet specific customer requirements – starting from a batch size of one.