DIY electrical bicycle

Gate driver based PWM build

IR2111 gate driver

Gas handle

Voltages

green = Vout
Red 5V
Black = gnd
no throttle = 4.43V
full gas = 1.02V
1.02 / 0.01948 = 52,4 = 0b00110101 => measured to 56 via adc = 0b00111000
4,43 / 0,01948 = 227,4 = 0b11100011
4,3 / 0,01948 = 220 => 210 = 0b11010010 -because small gap with 0 throttle

PWM

0b00111000= 99%
0b11010010 = 0%

translate into" logarithmic" steps
56 -> 210 =154 steps
0 - 99% for pwm is 0-253 binary

PORTD pin 6
output pin for the PWM mode

Brake handle

no brake
4 = 0b0000100
full brake
133 = 0b10000101
=> >125 = 0b1111101

Current sensor

Using the 30A model:

ADC at 19.48mV / step
DC motor built for 250W
simplified:
(4,5-2,5)/0,066 = 30,3A

Battery:

ADC battery voltage via voltage divider and 5.1V zener protection
4,2V is fully charged => ADC value of 215,6=0b11011000

Full

6s -> 4.20V*6 = 25,20V
250W/25,20 = 9,92A => (max current allowed for voltage level)
(x-2,5)/0,066=9,92A
=> x =0,066*9,92A + 2.50 = 3,15 => 3,15/0,01948 =161,95=> 0b10100010 on the ADC

Empty

6s -> 3.6*6 = 21,60V
250W/21,60V = 11,57A => (max current allowed for voltage level)
(x-2,5)/0,066=11,57A
=> x =0,066*11,57 + 2.5 = 3,26 => 3,26/0,01948 =167,55=> 0b10101000 on the ADC

readout is for battery charge level
100% 4.20 volts
90% 4.15
80% 4.10
70% 4.05
60% 4.00
50% 3.95
40% 3.90
30% 3.85
20% 3.80
10% 3.70
using "pessimistic" scale

in code

// 80% 4.10 * 6 = 24.6V
// 70% 4.05
// 60% 4.00
// 50% 3.95 * 6 = 23,7V
// 40% 3.90
// 30% 3.85 * 6 = 23,1V

Ignition

spark supressor 2.2kΩ
25/2200 = 0,01A
battery:
16Ah / 0.01A =1440h = 60days? on the bike

resistor placed between connectors

Schematic

Driver board

19V zener as gate protection
60V zener as transient protection
IRF2807 mosfet x4 75V
gate pulldown resistor for high side
IR2111 driver
transistor BC639 for stable PWM pulldown rail to GND
High output and low output via 10 Ω resistors

I/O board

*5.1V zener as input protection for the battery voltage divider
*LM7805 5V LDO as VCC for the arduino(more reliable)
*2x 100kΩ as voltage divider 1:6 with 2.4k short circuit protection
*headers from the original motor controller

Prototype board

each part of the bike tested on prototyping board
step by step testing of each individual component and finally combining them
separate rails for 5V, 12V and battery (6s Lipo)
arduino
gate driver IR2111
Mosfets IRF2807
voltage divider
"gas" handle
brake handle
low medium high LED on handle
Current sensor module ACS712 (20A)

done step by step to verify function