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Vehicle Goals

  1. Complete the race

  2. Cover the greatest possible distance in a given amount of time

Hardware Goals

  1. Fulfill regulatory requirements for competition

  2. Enable foundational systems required for the efficient operation of a solar vehicle

  3. Maintain high availability to fulfill the above functions

Design Philosophy

The hardware system is highly mission-focused and strives for simplicity while fulfilling the intended goals. The general design philosophy follow’s Elon Musk’s steps for good design:

  1. Establish and challenge requirements: A top-down design approach is taken, starting with system goals and distilling those down to functional and engineering requirements. Requirements are constantly challenged to ensure they accurately reflect the goals of the system. Bias is taken towards having the lowest possible number of requirements to ensure a lean system. If a requirement is missed it can be added at a later stage. Conversely, it is very unlikely that an unnecessary requirement will be identified at a later stage and removed.

  2. Delete parts: All parts of the system are analyzed and their existence justified. Components not required to fulfill the predetermined requirements should be removed from the system. Before attempting to solve a problem, it should be determined whether the problem needs to be solved in the first place.

  3. Simplify and optimize: The remaining parts are simplified and optimized for the requirement they are intended to fulfill. Simplicity improves efficiency, reduces the chances of failure, and shortens the development cycle which ensures a higher chance of success. However, optimization should not be performed on parts that shouldn't exist, hence it is the last stage in the design process.

High Voltage

Main Power Switch

The main power switch consists of 3 EV200 series relays. One relay is located at each terminal of the main battery and at the positive terminal of the solar input, so that the battery, motor, and solar array can be disconnected from each other. The main power switch is located inside the battery enclosure and controlled by BMS system from the carrier board.

 Old

Project

Summary

Controller Board

The “brain” of the boards; all boards that require ‘decision making’ or firmware-controlled inputs or outputs will have a controller board

Power Distribution

This board controls the power flow of all other devices in the car. It chooses who gets power, where the source of the power is, and monitors the power drawn

Power Select: selects the power source that the car draws power from. It selects between the AUX (usually used only for fans, horn, telemetry, main contactor relays), and DCDC (LV power from main pack)

Power Distribution: contains many firmware-controlled load switches that deliver power to all other boards/devices on the vehicles (boards, fans, horn, lights, etc). Also monitors the current draw for each load. Contains many connectors for other boards to plug into

Disconnects the battery if the voltage falls below a certain threshold.

Provides additional protection features, including

  • fuse to limit short-circuit current

  • inrush-current limiting

  • reverse polarity protection.

Centre Console

Serves as the hub of communication between the driver and the car. Displays useful information (speed, battery state, left/right turn signals, Battery Protection System warnings) to the driver in the form of LEDs and 7-segment displays.

It also receives input from 6 buttons, allowing the driver to Power On the vehicle, switch drive states (Drive, Neutral, Reverse), and enable/disable regen braking and hazard lights.

Motor Controller Interface (MCI)

Talks to motor controllers, we control the motors/get motor information through this board. 

BMS Carrier

This board is responsible for protecting the battery. Its responsibilities are:

  • Logging Voltage, Current, Temperature

  • Calculating the state of charge

  • Detecting battery faults and acting upon them

BMS AFE

Used to measure cell voltage and temperatures from each individual battery module, and also keep the cells balanced

BMS Current Sense

Measures the total current flowing from the battery pack.

DCDC

Converts the high voltage (110-150V) to the necessary low voltage of 12V nominal (ends up being 13-14V)

Pedal

Measures the angle of both pedals in the car (accelerator and brakes). This information is used to know how much each pedal is pressed, and then use this information to execute some functions (e.g if the accelerator is not pressed then regen braking will occur; if brakes are pressed, then brake lights should turn on)

Steering

Used for measuring steering angle as well as controls present on the stalk (lights, signals, horn).

Solar Sense/MPPTs

Solar sense: Measures the array module and array voltage, temperature, current

MPPT: Converting high current low voltage output from the solar panels into low current high voltage power compatible with our batteries and motors

Steering Stalk

The physical steering stalk that the driver uses, taken off an old vehicle, currently in the bay. It contains its own circuitry that must be understood such that we can interface with it and understand how to read its inputs.

Motor Testing

To test the motor and motor controller work correctly

Electrical Systems PVDR/VDR

Comprehensive design report including technical documents mechanical systems, electrical systems, batteries, and solar cells.

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