CAN Control System for an Electric Vehicle
Thesis DisciplineElectrical Engineering
Degree GrantorUniversity of Canterbury
Degree NameMaster of Engineering
The University of Canterbury has purchased a 1992 Toyota MR2 and used it as the platform to construct a new electric car. Similar to the common combustion engine vehicle, electric vehicles require control systems to control the operation of 12Vdc auxiliary loads, such as lights, indicators and windscreen wipers, where traditional technology results in a large number of wires in the wiring harness. Also, with the added complexity of modern vehicles, the need for integrating independent control systems together has become very important in providing safer and more efficient vehicles. To reduce the number of wires and make it possible for different control systems to communicate, and so perform more complex tasks, a flexible and reliable control system is used. The CAN (Controller Area Network) control system is a simple two-wire differential serial bus system, which was developed by Bosch for automotive applications in the early 1980s. The power and control system within the vehicle is named the "Power Distribution Network" and it is implemented by using multiple power converters and the CAN control system. This thesis presents the design, implementation, and test results of the CAN control system for the MR2. The 312Vdc nominal battery voltage is converted to an intermediate voltage of 48Vdc. This configuration is considered more efficient than the usual 12Vdc distribution system since smaller and lighter wires can be used to carry the same amount of power. The power distribution network operates off the 48Vdc intermediate voltage, and provides 12Vdc output to power all auxiliaries within the vehicle. The Power Distribution Network is implemented with two major subsystems: the auxiliary power system, which consists of multiple converters to step-down voltage from the 48Vdc intermediate voltage to the 12Vdc, and the CAN control system, which is developed to control and integrate the 12Vdc auxiliary loads within the vehicle. The prototype CAN control system is fully operational and has been tested with 12Vdc loads which are used to simulate most of the auxiliary loads in the vehicle. Experimental measurements show that the prototype is able to successfully control and maintain the network of independent nodes. This confirms that in principle the CAN control system is suitable for controlling the auxiliary loads in an electric vehicle.