The electrical systems team is responsible for motor integration, battery pack design, software & telemetry, battery management, sensors, motor control, and rider interface. Hands-on hardware skills, coding, and wiring skills are prevalent through the electrical. Some electrical systems projects are listed below.
The accumulator, or battery pack, is another essential component of our bike as its main job is to energize the motor controller. Some energy, however, will be dedicated to the lower voltage systems through the DC/DC converter. We plan to have between 50 and 80 LiPo cells connected in an assortment of series and parallel, with a maximum voltage of 110V. We also monitor the temperature in various places around the accumulator to ensure operational safety.
The motorcycle’s powerplant is an electric motor that converts electrical energy into mechanical energy which turns the rear wheel. For our bike, we are using the ME1507 PMAC motor, which is a radial flux, internal permanent magnet rotor. This powerful motor is capable of up to 30kW peak power. With this power there will be considerable heat generation so we have to make sure we are monitoring its power usage and temperature. We read this information into a central board on the bike and can display these metrics on the rider’s display.
The battery management system (BMS) is a device that monitors, protects, and balances the battery cell. Due to the typical variance of the internal resistance of Lithium ion battery cells, not all cells can be considered to have the same charge and discharge rates, despite being the same chemistry and size. This can lead to battery cells that operate out of their safe operating area therefore causing fires, damaged components, and poor bike performance. Our custom BMS will be designed to keep the cells within balance, monitor the voltage and temperature of each cell, and have high and low voltage cutoffs to act as emergency shutdowns.
Not everything in our system is going to run on 110V, which is what we expect our battery pack to output. For this purpose, we are using a DC/DC converter to take in that high voltage and put out a lower voltage of 12V in order to power most of the smaller components in our system, such as our display.
The motor controller, or inverter, is what tells our motor how fast to spin. It does this based on information it receives from the throttle and feedback on how fast the motor is currently spinning. We plan to use the Sevcon Gen 4 Size 6, 80V. This will get the most out of our motor due to the specs of the controller and the motor matching up nicely. The controller will also send information to our display via CANbus connection.
The choice for the dashboard display/interface is a Raspberry Pi Zero fixed with an OLED screen. This display will be in charge of reporting the voltage of the HV system to the rider along with other desirable numbers such as the speed of the bike, battery gauge, or temperature readouts. The Raspberry Pi Zero will be communicating with the rest of the bike components, such as the BMS and motor controller via CAN bus.