Curriculum

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====== Motors ======

Prerequisite: [[Electricity]]

Convert electrical energy to mechanical energy.
===== Make a motor =====

Use 31 AWG wire.  Enamel coated.  The enamel acts as an insulator.


===== Electronics =====

V volts    V voltage
I amps     A current
R ohms     Ω resistance
P power    W watts

ohm's law: V = I * R

P = V * I or W = V * A



===== Specs =====

Power rating

Max power

Amp rating

Max amps, max current that can safely pass through the motor, 
depends on coil wire thickness and heat dissipation mechanism.

RPM - normally the no-load rpm

Max RPM


===== Power =====

volts

amps

more volts, less amps, thinner wires, less weight

examples
  * Tesla motors run at 400 volts.
  * Porsche at 800V.

Power rating of 12 v dc motor can be few watt to kw depending on design and size: 
tape recorder, cd motor, industrial carriage, lifter, automobiles, etc.

Powerful supply sources are required for big 12v motors.
A battery cell can be used for small 12v motors.

=== Power ===

1 kilowatt = 1 horsepower

kilowatt, horsepower, torque, newton, 

rpm, tachometer, hall sensor

power, force, energy, work

energy
power
force
work

^ property ^ unit of measurement ^        ^
| energy | joule, calorie        | scalar |
| work   | joule, calorie        | scalar |
| force  | Newton N (formerly P) | vector |
| power  | horsepower HP         | scalar |


===== Torque =====

When we use the word force, we usually mean a linear force, a push or a pull on an object.

Torque is a rotational force, a twist of an object.

=== Linear Force ===

F = ma

Force = mass times acceleration.

Acceleration is rate of change of velocity
velocity is 10 meters per second
the acceleration 10 meters per second per second



A linear force is acceleration.

A Newton is a measure of linear force.\\
The amount of force it takes to accelerate 1 kg of mass 
at a rate of 1 metre per second squared.

\begin{align}
1 \text{ Newton} = 1 \text{ kg} \frac{m}{s^2}
\end{align}

How do you measure acceleration?
0 to 60 in 10 seconds.  Whats the acceleration?
Let's make it 0 to 100 kph in 10 seconds.
acceleration = 100 km /10 * seconds^2
= 10 km / second^2

I find it difficult to think about force this way.
I would rather just think about speed.
If I push a 10 kg weight 1 meter.
That might be done in 1 second, or it might take me all day.
A stronger force can do it in a shorter time.

So, push a 1 kg weight, a distance of 1 meter, in 10 seconds.
But that is not a reasonable measure of force, because of momentum.
Once the weight is moving, it will continue to move at that speed indefinitely.
It will require force to stop the movement, or to speed it up.
Therefore we measure acceleration.

A force can be applied to get an object moving, and it will continue moving with no force.
So to measure the force, we must measure the acceleration.

=== Force of Gravity ====

The acceleration due to gravity is 9.8 Newtons.

An object falls to earth accelerating at 9.8 meters per second every second.

9.8 meters = 32 feet

=== Rotational Force ===

When I hear the term Newton-meter, I immediately think, that must mean to move a 

The Newton-meter is a measure of rotational force, or Torque.

I find the term Newton-meter misleading because it sounds like 

The term does NOT mean moving 1 Newton a distance of 1 meter.
A foot-pound of force means moving a 1 pound mass through a distance of one foot.

=== How to measure torque ===




=== Stall Torque === 

Attach a one-meter arm to a motor's drive shaft, 
hang a weight on the arm, and see if the motor can lift it.

So what if I rig a motor in this way and find it can lift a 1 kg weight. 

If I buy a torque wrench in America, what are the units?  foot-lbs?

power vs force: HP, Watts, Nm/s

What about the weight of the arm?




=== Output Watts ===

speed and torque

=== Watts to Torque conversion ===

Bullshit!!

Watts to Torque Calculator
https://www.electrical4u.net/calculator/watt-w-to-torque-nm-conversion-calculator/

This webpage has replicated dozens of clickbait sites.

Tradeoffs
  * current vs voltage
  * voltage vs speed

This makes us ask:  is Watts a viable number?

We use watts as a single number to rate and compare motors.

What we really want to know about is speed and torque.

And what we really need to know to hook a motor up is charge and current.

DeWalt uses the term "Unit Watts Out".  
As opposed to the rated watts which would be watts in.
https://www.protoolreviews.com/max-watts-out/

=== Efficiency, input power, output power ===



input: 8000 watts (amps * volts)

output: torque and speed

How do you compare these two?

efficiency = output power / input power

Watts input = volts * amps

Watts output = ?, HP * 746, torque * speed * a constant? 

horsepower = 

input voltage, aka supply voltage

Shaft power vs voltage and current \\
https://www.engineeringtoolbox.com/electrical-motor-horsepower-d_653.html

DC Motor Specifications \\
http://www.learningaboutelectronics.com/Articles/DC-motor-specifications.php

=== Summary of Equations ===

W = A * V  && watts = amps * volts  & power = current * voltage
V = A * R  && volts = amps * resistance  & voltage = current * resistance 


===== Hub vs Mid =====

sprocket teeth, rear/front ratio 3.0

tire size, rimsize, rpm, top speed

max eff at 75%

temperature, cooling

waterproofing ?

===== Bernoulli =====

probability

nozzle

fluid dynamics, water pressure

can be applied to many problems



Updated December 28, 2020
By Lee Johnson
How do airplanes fly? Why does a curveball follow such a strange path? And why do you have to board up the outside of your windows during a storm? The answers to all of these questions are the same: They’re a result of Bernoulli’s principle.

ome other examples of Bernoulli’s principle in action can help to clarify the concepts. The most well-known is the example comes from aerodynamics and the study of airplane wing design, or airfoils (although there are some minor disagreements about the details).

The top part of an airplane wing is curved while the bottom is flat, and because the air stream passes from one edge of the wing to the other in equal periods of time, this leads to a lower pressure on the top of the wing than on the bottom of the wing. The accompanying pressure difference (according to Bernoulli’s principle) creates the lift force that gives the plane lift and helps it get off the ground.

Hydroelectric power plants also depend on the Bernoulli principle to work, in one of two ways. First, in a hydroelectric dam, water from a reservoir travels down some large tubes called penstocks, before striking a turbine at the end. In terms of Bernoulli’s equation, the gravitational potential energy decreases as the water travels down the pipe, but in many designs, the water exits at the same speed. By the equation, it’s clear that there must have been a change in pressure to balance the equation, and indeed, this type of turbine takes its energy from the pressure energy in the fluid.

Arguably a simpler type of turbine to understand is called an impulse turbine. This works by reducing the size of tube before the turbine (using a nozzle), which increases the velocity of the water (according to the continuity equation) and reduces the pressure (by Bernoulli’s principle). The transfer of energy in this case comes from the kinetic energy of the water.

==== History ====

Early experimenters around 1800 included:
  * Benjamin Franklin
  * Charles-Augustin de Coulomb
  * Andre-Marie Ampere
  * Michael Faraday
  * Anyos Jedlik

The first motor design included:
  * stator - a stationary magnetic field
  * rotor - a rotating magnetic field
  * commutator - a rotary electrical switch that reverses circuit through the rotor

==== Structure ====

AC vs DC

induction motor vs reluctance motor

three-phase motor - heavy loads, industrial

single-phase motor - light loads, household appliances like fans

two-phase - ?

fixed-speed 

variable-frequency drives (VFD) - energy saving, variable-torque

squirrel-cage induction motor - 

brushed DC motor (BDC)

brushless DC motor (BLDC)

servo

stepper

  * induction == asynchronous 
    * wound
    * squirrel-cage
    * single-phase
    * three-phase


==== EMF ====

back EMF

electro motive force (EMF)



===== Examples =====

=== QS Motors ===
located Taizhou, Zhejiang, China (south of Shanghai) //
mfg motors, controllers, kits, 3000W to 8000W //
[[http://www.qs-motor.com/product-catagory/bldc-motor/ | product list]]
{{https://ae01.alicdn.com/kf/H299cb0d39c9b408f88e22c18a8cd77d7X.jpg?200}}

=== Golden Motor ===
Changzhou, Jiangsu, China (near Shanghai) \\
[[http://goldenmotor.com/frame-bldcmotor.htm | BLDC motors 3/5/10/20 KW]]
[[https://www.alibaba.com/product-detail/BLDC-motor-5000W-electric-motorcycle-kit_1600071540851.html?spm=a2700.7724857.normal_offer.d_image.4f0373bc2TutEg | at alibaba]]
{{https://www.goldenmotor.com/img/5KWFanCooling.jpg?200}}

=== Wuxi Shenma ===
located in Wuxi, Jiangsu, China (near Shanghai), mostly focused on disc brakes, no website \\
DC Motor 138 3KW 5KW 72V 100KPH Mid Drive Motor with Disc Brake, 48-96V 3000-5000W \\
as of 2022 $329.00 \\
[[https://www.alibaba.com/product-detail/DC-Motorcycles-Motor-138-3KW-5KW_1600411095197.html?spm=a2700.7724857.normal_offer.d_title.4f0373bc2TutEg | at alibaba]]
{{https://s.alicdn.com/@sc04/kf/H5426c9787dfd416094c9a2bdc4827721E/253302854/H5426c9787dfd416094c9a2bdc4827721E.jpg?quality=close:200}}

===== Todo =====
https://www.differencebetween.com/difference-between-force-and-vs-pressure/ \\
https://arachnoid.com/gravitation_equations/force_weight.html \\
https://circuitglobe.com/electrical-load.html \\
https://sciencing.com/convert-amps-electrons-per-second-8628812.html \\
https://brainmass.com/physics/electric/current-number-electrons-second-44247 \\
https://www.rapidtables.com/calc/electric/watt-volt-amp-calculator.html \\
https://www.youtube.com/watch?v=wBjT7KZqVuM \\
https://en.wikipedia.org/wiki/Bernoulli%27s_principle \\
https://sciencing.com/fluid-dynamics-overview-basics-terminology-equations-13723386.html \\
https://www.alibaba.com/trade/search?fsb=y&IndexArea=product_en&CatId=&SearchText=18650 \\
https://www.alibaba.com/trade/search?fsb=y&IndexArea=product_en&CatId=&tab=all&SearchText=bldc+qs&viewtype= \\
https://www.discoverboating.com/resources/electricity-101-for-boaters \\
https://owlcation.com/stem/Watt-are-Amps-and-Volts \\
https://duckduckgo.com/?q=amps+to+amp+hours&t=brave&ia=web \\

===== Motor Controller =====

aka Speed Controller or Electronic Speed Controller (ESC)

Functions:
  * Starting - some loads require greater torque to start moving than to keep moving
  * Braking - some motors regenerative braking
  * Reversing the rotation
  * Controlling speed
  * Controlling torque

Controller for AC Motor

Controller for DC Motor

Pulse Width Modulation (PWM)

===== Regenerative Braking =====

freewheel - aka overrunning clutch.  a device in a transmission that disengages the driveshaft from the driven shaft when the driven shaft rotates faster than the driveshaft.

When rider reduces the throttle,
  * a clutch disengages and the vehicle coasts regardless of motor rpm (freewheeling)
  * the wheels drive the motor faster than what the throttle calls for (braking)

freewheeling vs engine braking
  * rider
  * throttle
  * controller


===== Applications =====

== Drone ==
  * rpm high
  * load: light
  * weight: weight
  * voltage: low (to keep battery weight down)
  * constant velocity (Kv) - rpm per volt

== Water pump ==
  * rpm: constant, continuous 

== Elevator ==
  * rpm: constant, with start and top
  * brake: mechanical brake when power off

== Motorcycle mid ==

  * rpm: 4500 - chain drive with 3:1 sprocket ratio
  * voltage 72v
  * watts 3000 to 10000
  * amps
  * brake: regen or freewheel at driver's option

== Motorcycle hub ==

  * rpm: 1500 - direct correlation to wheel diameter and vehicle speed
  * voltage 72v
  * watts 3000 to 10000
  * amps
  * brake: regen or freewheel at driver's option

AC Motors

single phase

two phase

three phase

Generators

single phase.  Into homes. 120 volts in America.  240 volts everywhere else.

two phase

three phase

Three wires.  voltage and current 120 degrees out of phase on the three wires.  

high voltage on each wire.  120 degrees apart.

===== Electric Power =====

Generation, transmission, and distribution of electricity.

Several systems for electric power distribution have been attempted.  Evidently Edison argued for DC but Tesla prevailed with AC.

=== AC ===

AC could easily be transformed to higher voltages for long distance transmission, and than transformed down to lower voltages for distribution.  A grid is populated with numerous transformers along the way.

== Three-Phase ==
The most common method used by electrical grids worldwide to transmit power.  Three wires, the voltage and current of each wire 120 degrees out of phase.

Some factories and large buildings take in the three-phase current and use it directly in three-phase motors with large loads like elevators and industrial pumps.

== Two-Phase ==
Early 1900's.  Now mostly replaced by three-phase.  Commonly used with four wires, two circuits, each circuit out of phase by 90 degrees.

== Single-Phase ==
The most common method of distribution into the household.  Single phase is split off at the transformer for each household.

Single-phase motors sometimes need an extra voltage to get started.  My air conditioner has two such motors, one for the compressor and one for the fan.  A starter component, which contains two capacitors, is used to start the two motors.

The standard U.S. household wiring design has two 120 volt "hot" wires and a neutral which is at ground potential. The two 120 volt wires are obtained by grounding the centertap of the transformer supplying the house so that when one hot wire is swinging positive with respect to ground, the other is swinging negative. This versatile design allows the use of either hot wire to supply the standard 120 volt household circuits. For higher power applications like clothes dryers, electric ranges, air conditioners, etc. , both hot wires can be used to produce a 240 volt circuit.


==== International Power Grids ====

^                               ^ USA     ^ Thailand ^ other countries      ^
|frequency (hz)                 | 60      | 50       | either 50 or 60      |
|household single-phase (volts) | 120/240 | 230      | mostly 240, some 120 |
|industrial two-phase (volts)   | 240/480 | 380      | between 240 and 480  |

https://en.wikipedia.org/wiki/Mains_electricity_by_country

=== DC ===

Modern electronics can raise the voltage of DC with high efficiency, so now high-voltage direct current (HVDC) can give lower losses over long distances.


==== Resistance, Resistivity, Electromagnet ====

\begin{align}

R &= ρ × \frac{L}{A} \\
\text{where:}\\
R &= \text{resistance in Ω} \\
ρ &= \text{resistivity of material in Ωm }\\
L &= \text{length of the wire in m} \\
A &= \text{cross-sectional area of the wire in m}^{2} \\

\end{align}

source 
https://www.omnicalculator.com/physics/wire-resistance#conductance-formula-and-resistance-formula