Power SOLAR & ELECTRIC POWER

The GO The Green Tricycle uses electric power. This requires: ◦A Charge ◦Battery ◦Controller ◦Motor ChargeBatteryControllerMotor

How Much Power Do I Need? P req =M*g*V*µ+(q*A*V*Cd) P req =Power Required in Watts (W) M=Mass of Vehicle (kg) g=Gravitational Acceleration (9.81m/s 2 ) V=Vehicle Forward Velocity (m/s) µ=Coefficient of Rolling Resistance (Use rubber-to-concrete in ideal conditions to start) q=1/2*ρ*V 2 ◦(ρ=Density [1.225 kg/m 3 ]) A=Vehivle Frontal Area (m 3 ) (Use A of Similar Sized Vehicle) Cd=Vehicle Drag Coefficient (Use Cd of Similar Sized Vehicle ~0.55)

What’s My “Range”? Determine battery’s Watt-Hour capacity (Battery Voltage * Battery Amp Hour Rating) To get runtime, Divide Watt-Hour capacity (above), by Power Required in watts (see previous slide) ◦Remember Power Required is a function of Velocity (Depends on Velocity) Get RANGE by multiplying forward velocity by runtime at that velocity ◦See next slide for an example of a graph that can be created with these calculations

Power Considerations in the Design of a Green-Energy Tricycle Motor Battery Golden Motor Magic Pie V5 48V 20Ah Samsung Pedal system connects to rear hub motor powered by battery Top Speed and Power Calculations

What else to consider? Torque from Start Top Speed Battery Capacity/Output Will the rider pedaling assist the motor, or will motor produce all power?

Worked Example

Solar Power

A solar panel works by allowing photons (particles of light) to knock electrons free from atoms, generating a flow of electricity. Solar panels actually comprise many, smaller units called photovoltaic cells. Many cells linked together make up a solar panel. 3 Major Solar Panel Manufacturers (Forbes): ◦Trina Solar, Yingli Solar, Canadian solar Specs and Cost: ◦CS6K-P-PG ◦Dimension: in X 64.96in X.39in ◦Peak Power: Watts ◦Cost: ~$200 ◦Weight: lbs ◦YGE 60 Cell Series ◦Dimensions : 64.57in X 38.98in X 1.38in ◦Peak Power: Watts ◦Cost: ~$200 ◦Weight: 40.8 lbs

Solar Power Powering the Vehicle? ◦Using a Solar Panel for power requires ◦Charge Controller - provides suitable charging capabilities for the battery ◦Inverter – produces usable power from solar power for devices or motors ◦They’re not free of cost and weight. ◦They aren’t “pretty” & don’t come in customizable shapes. ◦(See top right image) ◦In many cases, they’re better left behind. ◦It’s not efficient for small solar panel alone to move a large vehicle like the Green Tricycle.

Batteries

Batteries - It’s all about storage Keeping Charged: ◦Electric vehicles store energy in a battery. When this energy is depleted, it must be recharged. We do this everyday with our high use electronic devices (smartphones, laptops…) ◦Considerations: ◦Avoid deep cycling - A partial discharge is better than a full discharge. ◦Avoid abuse - A battery is stressed more if discharged and charged too quickly Tesla vehicles have large batteries in chassis

Batteries - It’s all about storage Cost ◦Nickel metal hydride batteries are the less-expensive technology. Weight ◦NiMH batteries are larger and heavier than Li-ion batteries. ◦Weight matters in our tricycle for maximum mileage. Power ◦Li-ion and NiMH batteries can actually hold a similar amount of power. ◦Li-ion cells can be charged and discharged more rapidly. ◦Li-ion doesn't have as much of a "memory effect," which occurs when a battery is recharged before it is fully empty. This can diminish a battery's capacity. Durability ◦NiMH has an advantage. ◦Some Li-ion batteries don't last as long in extreme temperatures, particularly in very hot climates.

Batteries - It’s all about storage Other Options? Deep Cycle Auto/Marine Batteries ◦Easily swappable/widely available ◦Relatively low cost (typically $50-$200 dependent on size) ◦Not properly suited for multiple charge/recharges ◦Better suited for cold-cranking – getting an engine started ◦Best suited for use with an alternator to keep float charge

Getting More from Your Batteries This is how it works: ◦Batteries Connected in Series ◦Doubles Voltage (V), Capacity in Amp Hours (AH) Remains the Same. ◦Batteries Connected in Parallel ◦Doubles Capacity in Amp Hours (AH), Voltage (V) Remains the Same.

Controllers CONTROLLING YOUR MOTOR

How they work… Simplest case is a switch to connect a motor to a power source ◦On & Off. Stop & GO. Accurately control the speed and torque of the connected motor (or motors) ◦PWM: Pulse Width Modulation ◦Alternating “On & Off” signals at different frequencies that simulate speed control ◦Narrow Pulses=Slow. Wide Pulses=Fast

Motor

Focus on DC Motors Since batteries create “Direct Current (DC)” signals, Use an DC Motor for Simplicity AC Motor will require additional component called an inverter ◦Invertor takes DC signal and turns into AC A DC motor consist basically of two parts: ◦Stationary body of the motor called the “Stator” ◦Rotating inner part which rotates producing the movement called the “Rotor” Find a motor that produces enough Power & Torque for your worst case (from stop, heavy, etc…). See the wattage ratings and contact manufacturers to make the final judgment.

All-in-One Units Some suppliers sell “systems” that sometimes incorporate batteries, controllers and motors in one easy to manage package. Some examples used in the Green Tricycle project include: Bafang ◦ Magic Pie ◦

Our Green Tricycle Motor: Magic Pie 5 by Golden Motor Motor operates on a 48V source – Samsung Amp Hour lithium-ion battery. Tricycle can generate over 800 Watts of power to drive the vehicle. Motor uses regenerative braking system to store additional energy that would otherwise be wasted during braking. Motor is controlled by a throttle and includes a “cruise control” option for added operator comfort. Battery Plug-in to solar float charger or wall outlet to recharge.

Powertrain Components Magic Pie 5 Regenerative Braking Complete System Samsung E-Bike Battery 12 pounds 960 Watt Hours1000 Charges Bluetooth Connection 7.5 pounds 48 Volts

What Are Others Using? The Elf ◦Continuously variable transmission ◦Pedal-assisted motor mounted in middle of bike frame ◦750W DC Permanent Neodymium Magnet Motor ◦Lithium-ion NMC with BMS ◦48-V 10 Ah battery ◦Charged by solar panel or outlet HP Velotechnik S-Pedelec ◦Scorpion FS 26 ◦Start assist button ◦Rear hub motor ◦Thumb throttle on handlebar ◦500-watt rear wheel hub motor ◦36 V Li-Ion rechargeable battery ◦530 W-h capacity