Automotive test systems builder, CP Engineering finds the versatility
of the Unidrive ac drive just right for its range of engine testing
dynamometers
CP Engineering manufactures engine and chassis dynamometer test systems,
transmission test systems and other test rigs for the automotive
industry. It has supplied systems to many leading firms in this sector,
including Castrol, Cosworth Technology, Delphi and Shell. When the
company was looking to establish a partnership with a drives supplier,
Control Techniques' Unidrive caught its attention.
No competitive product could match the programming versatility of this
drive, which offered just the sort of features CP was seeking, including
an optional crank starting software module and fully regenerative braking
- a standard Unidrive feature that allows the energy of the engine
test-bed as it is braked, to be returned to the mains. This regenerative
braking feature also avoids having to build in additional cooling systems.
CP's 'Cadet' Windows NT based control and datalogging system's analogue
interface is synchronised to the drive's closed loop vector control. The
test systems require real time control and processing that is precisely
synchronised to give the same load/speed profile as a real vehicle. The
response of the control loop must thus remain consistently within a given
cycle time - typically 3.25ms. The drive also has to be capable of
motoring to simulate over-run conditions.
Cranking software, which resides in the Unidrive UD70 plug-in module,
provides protection for the drive shaft. As the engine fires and
accelerates, the drive switches to zero torque to simulate engine idling.
Apparently, this cannot be done with conventional dynamometers using
other makes of drive, and gives CP an edge on its competition.
We now use Control Techniques Unidrive as our drive of choice, says CP
Engineering managing director, Bob Ceen. We had a number of technical
issues with other drives, then we turned to Control Techniques to take a
closer look at Unidrive. This gave us all of the features we needed, but,
perhaps more importantly, the company was willing to give us direct
access to its engineering base, which proved invaluable in our
development of new systems.