Outline
This section covers the basics of how a solar car's electrical system works and how we've approached these challenges. This includes:
- System communication
- Power distribution
- Extracting energy from the sun
- Energy storage and keeping it safe
- Making the car move
- Driver interaction and usability
- Data collection
Intro
As an inherently electric vehicle, a solar car can be thought of as an extremely efficient electric car that charges its battery pack through energy collected from the sun instead of requiring the use of an external charger. Since the solar array is relatively small and solar cells have limited efficiency, the resulting goal is to minimize energy use during normal operation.
A solar car's electrical system involves a number of different sub-systems that are each responsible for a different task.
- Solar
- Photovoltaic (PV) array: Collects energy from the sun and is our primary source of power
- Maximum Power Point Tracker (MPPT): Maximizes the array's output and matches the battery voltage
- Motor System
- Motors: Generally special high-efficiency direct-drive brushless DC (BLDC) motors; responsible for actually moving the car
- Motor Controllers: Generates the electrical pulses in the correct order required to drive the motors
- Precharge Controllers: Precharges and discharges the capacitors in the motor controllers to prevent arcing and electric shocks
- HV Battery
- Battery Pack: Stores and outputs energy; extremely dangerous if not handled properly
- Battery Management System (BMS): Monitors the voltage, temperature, and current of the battery pack, ensuring that it stays within safe operating ranges
- Power Distribution: Handles low-voltage and high-voltage power rails; responsible for ensuring power is distributed properly and safely
- Low Voltage (LV): Power that's used for most boards. Typically 12V DC
- High Voltage (HV): Power from the solar array and battery pack. Used to drive the motors through the motor controllers. For MSXII/MSXIV, HV is between 90 V and 151.2 V.
- Driver Controls
- Lights: Handles all lights in and on the car
- Driver Input: Reads switches, buttons, and pedals and notifies the appropriate system
- Driver Display: Displays information for the driver such as speed and battery status
- Controller Area Network (CAN) bus: Automotive communication protocol; the network that systems communicate with each other over
- Telemetry: Collects and transmits data from the car to an external receiver for remote monitoring
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