Inverter driven test rigs simulate actual conditions.

Test rigs often use variable speed drives and motors to closely simulate real life conditions to allow for testing of a variety of components and assemblies during all stages of product development and manufacture.  Many are used in the automotive and aerospace industries, testing cars, motorcycles, trucks, tractors, racing cars, tanks, helicopters and jet engines.

The flexible control offered by AC variable speed inverter drives is well suited to test rig applications, as their response can be varied to simulate real conditions in a highly dynamic, accurate, linear and repeatable way.  They can stop and start quickly to replicate high speed events. For example, in an engine or transmission when the clutch is depressed, torque is instantly reduced to zero. When the clutch is released, torque is fully applied again very quickly. Direction can also be quickly reversed.

The most common types of automotive test rig are chassis dynamometers, engine dynamometers and transmission rigs. Chassis dynamometer testing usually employs one drive and motor per test unit axle or wheel, depending on the type of testing being performed, and power ranges from 7.5 to over 7000 kW are typical.

Regenerative Drives

Regeneration is often a key requirement. This means that the drive is able to regenerate electric power when the motor is absorbing energy or providing a load, returning this energy to the supply and reducing operational costs. The energy can also be recycled between drives, again reducing energy requirements.

Regenerative AC drives also bring a number of additional benefits: multi-pulse drive arrangements requiring bulky and expensive transformers are no longer required, additional flexibility is built into the drives and the drive provides very low harmonic distortion and unity power factor.

MULTI-DRIVE APPLICATIONS

Multi-drive solutions are used where there is more than one motor, with the motors back-to- back for example, one motoring and the other generating. The item under test will be between the two motor shafts, with energy being re-circulated on the common DC bus from which the drives are supplied. An example is in the testing of cab belts

TORQUE CONTROL

Drives for test rigs need to fulfil a number of key requirements, of which excellent torque response is the main one. Torque linearity and resolution must also be controllable over a wide speed range, as low speeds and high torques are an essential requirement when testing gearboxes and transmissions, for example.

ABB’s unique Direct Torque Control (DTC) function gives the fast torque rise times and response rates required for such high performance applications.

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