Curtiss-Wright motor controllers specified for university's Formula Hybrid-Powered vehicle
03 April 2015
The Rensselaer Polytechnic Institute (RPI) Formula Hybrid team has taken 6th Place overall in the 2014 Formula Hybrid Competition using PG Drives Technology’s Sigmadrive PM motor controllers to provide smooth and predictable speed control.
The RPI team worked year round to completely redesign and build the parallel hybrid-based DCMS vehicle which, for 2014, resulted in a mid-engine rear-wheel-drive car featuring a 38hp Kawasaki motorcycle engine mounted on the rear differential and coupled to a 79hp Agni 95-based main drive/traction motor.
In order for the DCMS to deliver racecar-level performance with a comparably small engine, much of the burden of power is left to the electric drive system, which uses a four-quadrant Sigmadrive to integrate the drive system with the vehicle’s CANbus.
Like a hybrid vehicle, the electric motor provides the DCMS with instant acceleration and regenerative braking, while the internal combustion engine will engage at a point determined by an on-board computer system and is controlled by the driver using a clutch and electronic throttle.
The Sigmadrive also allows the driver to regulate the power of the high output battery to deliver 1%, 50% or 100% of the available power going into the motor controller. Typically, this is achieved by applying pressure through the throttle pedal or selecting different gear ratios.
However, the vehicle design completely changes every year, and in 2014 the team did have traditional acceleration pedal links to its on-board main control system, passing a direct message to the analogue input of the basic throttle control system to deliver a specific percentage of power.
In certain circumstances the control system on the DCMS will make allowances for wheel spin, critical condition of the battery pack or overheating. However, generally it provides direct control of the percentage of torque coming through the motor controller.
Commenting on the reason for specifying PG Drives Technology’s Sigmadrive controller, RPI’s electrical supervisor Ricky Willems says: “Size and weight of the motor controllers were the most serious factors in the specification, and shape was also a major concern.
Compared to competitive motor controllers of similar ratings, the Sigmadrive was substantially smaller and lighter. Its form factor was thin, wide and long, which allowed it to be placed strategically below the driver and positioned vertically behind his back.”
He goes on to say that other features and factors that influenced the team’s decision on specifying the Sigmadrive controller included a large aluminium mounting surface that proved essential when the motors were at maximum output; and the regenerative braking feature, which meant the team didn’t need to design its own.
PG Drives Technology’s Sigmadrive provides smooth and predictable speed control of permanent magnet traction motors across a wide range of system voltages and power ratings.
Their advanced design includes features such as IMS technology, high-resolution current measurement, CANbus communications and extremely low heat dissipation. The Sigmadrive can also be configured for dual-traction applications and includes a range of dedicated electric power steer assist controllers.
Curtiss-Wright’s Industrial division is a recognized leader in the production of critical controls and assemblies for speciality vehicles, including sensors, electronic throttle controls and joysticks.
For further information about products and other innovative solutions available from Curtiss-Wright’s Industrial division, click here or call +44 (0)1425 271444.
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