As output stage of the controller grab the source power (from Battery) and supply to the load (Motor), so i planned to design the Output portion first.
Output stage componets :
Mosfet
IGBT drivers
Current sensors.
Thick Busbar / Thick Soldering for connecting the Mosfet output to the Motor phase leads.
Output stage Circuit :
Full bridge
Double Puse test.
--------------
What is MOSFET ?
MOSFET is the 3 terminal/lead electronic device, terminals are Source(S), Gate (G), Drain (D)
Mosfet is just a switch, but it ON only when the Signal/voltage given in Terminal G (gate),
if the gate signal is given to Mosfet, it start conducting that is, it supply the power connected to Terminal S (source) to the Terminal D (drain)
Figure shows Terminal 'S' connected to Battery, Terminal 'D' connected to Motor phase, Terminal 'G' connected to IGBT driver
Example :
Battery is connected to the Terminal S (source) of MOSFET,
Motor is Connected to the Terminal D (drain) of MOSFET,
IGBT Driver is connected to the Terminal G (gate).
[ON] Once the Signal/Voltage from IGBT Driver is given to Terminal G, Current flow occurs from battery to Motor.
[OFF] If no signal/voltage given from IGBT Driver to Terminal G, NO Current flow occurs from battery to Motor.
Practical Mosfet :
theoritically, if we removed or stopped the supply to the Terminal G (gate), then terminal S (source) to Terminal D (drain) become open (no conduction), but this is not happening preactically, see the below video
https://www.youtube.com/watch?v=UwzepcZQyQc
For ON we need to give signal/supply to the Terminal G, for OFF even after removal of gate signal still MOSFET conduct, so we need to ground the Terminal G, then only it stop conduct.
How many FET going to use ..??
It is one of the important question regarding controller. In single controller we're going to use "Full Bridge" circuit, so the numbers must be like 6, 12, 18, 24 FET (multiples of 6 is the simple rule).
I planned to use 6 FET for my controller, as it is the minimum one.
Per MOSFET power dissipation :
MOSFET name and number :
Current Sensor :
Once we accelerate the bicycle using throttle, then the current flow increases, sometime it may damage the controller and motor, as they have certain limit, if it crossed the limit, then they damage, so we have to measure the current flow in phase wires (between controller and motor), and using the current sensor, and supply the measured current value to microcontroller, as we already store/programmed the certain current limit, so microcontroller compare the realtime current flow in phase wires with the preset limiting value, if it cross the preset current limiting value, then Microcontroller stop the signal to MOSFET, once the current flow value is below the preset value then it automatically turn ON.
Buck Converter :
BLDC motor is powered by battery in which controller sits in center between baatery and motor, but electronic components in controller also need a electric supply (in few 5v to 12v), so to stepdown the volatage we need a Buck converter.
Double Pulse Tester :
To know the switching characterisitics of MOSFET for our setup, we need to do one test called "Double Pulse Test", using this test we can understood more about the MOSFET temperature for certain current value and all, it is something like simulation without original load (motor)
------------
Choosing the Components :
MOSFET Choosing :
Choosing MOSFET for controller depends on peak current and peak voltage, if we used the less rating MOSFET means, due to power dissipation overheat, it simply burns, so we always have to choose the higher rating MOSFET.
IRFP4110 - 100 A , 100 V, Download datasheet
IRFP4468 - 190 A , 100 V, Download datasheet
We can decide from above mosfet ratings, still lot of high rating mosfets are there for higher power vehicles like car/bus/truck, but thing is higher power MOSFET need a proper cooling.
IGBT Driver Choosing :
IRS2186 -
Current Sensor choosing :
ACS758 -
Buck Converter choosing :
LTC3638 -
Output stage componets :
Mosfet
IGBT drivers
Current sensors.
Thick Busbar / Thick Soldering for connecting the Mosfet output to the Motor phase leads.
Output stage Circuit :
Full bridge
Double Puse test.
--------------
What is MOSFET ?
MOSFET is the 3 terminal/lead electronic device, terminals are Source(S), Gate (G), Drain (D)
Mosfet is just a switch, but it ON only when the Signal/voltage given in Terminal G (gate),
if the gate signal is given to Mosfet, it start conducting that is, it supply the power connected to Terminal S (source) to the Terminal D (drain)
P type Mosfet Symbol
Figure shows Terminal 'S' connected to Battery, Terminal 'D' connected to Motor phase, Terminal 'G' connected to IGBT driver
Example :
Battery is connected to the Terminal S (source) of MOSFET,
Motor is Connected to the Terminal D (drain) of MOSFET,
IGBT Driver is connected to the Terminal G (gate).
[ON] Once the Signal/Voltage from IGBT Driver is given to Terminal G, Current flow occurs from battery to Motor.
[OFF] If no signal/voltage given from IGBT Driver to Terminal G, NO Current flow occurs from battery to Motor.
Practical Mosfet :
theoritically, if we removed or stopped the supply to the Terminal G (gate), then terminal S (source) to Terminal D (drain) become open (no conduction), but this is not happening preactically, see the below video
https://www.youtube.com/watch?v=UwzepcZQyQc
For ON we need to give signal/supply to the Terminal G, for OFF even after removal of gate signal still MOSFET conduct, so we need to ground the Terminal G, then only it stop conduct.
How many FET going to use ..??
It is one of the important question regarding controller. In single controller we're going to use "Full Bridge" circuit, so the numbers must be like 6, 12, 18, 24 FET (multiples of 6 is the simple rule).
I planned to use 6 FET for my controller, as it is the minimum one.
Per MOSFET power dissipation :
MOSFET name and number :
Current Sensor :
Once we accelerate the bicycle using throttle, then the current flow increases, sometime it may damage the controller and motor, as they have certain limit, if it crossed the limit, then they damage, so we have to measure the current flow in phase wires (between controller and motor), and using the current sensor, and supply the measured current value to microcontroller, as we already store/programmed the certain current limit, so microcontroller compare the realtime current flow in phase wires with the preset limiting value, if it cross the preset current limiting value, then Microcontroller stop the signal to MOSFET, once the current flow value is below the preset value then it automatically turn ON.
Buck Converter :
BLDC motor is powered by battery in which controller sits in center between baatery and motor, but electronic components in controller also need a electric supply (in few 5v to 12v), so to stepdown the volatage we need a Buck converter.
Double Pulse Tester :
To know the switching characterisitics of MOSFET for our setup, we need to do one test called "Double Pulse Test", using this test we can understood more about the MOSFET temperature for certain current value and all, it is something like simulation without original load (motor)
------------
Choosing the Components :
MOSFET Choosing :
Choosing MOSFET for controller depends on peak current and peak voltage, if we used the less rating MOSFET means, due to power dissipation overheat, it simply burns, so we always have to choose the higher rating MOSFET.
IRFP4110 - 100 A , 100 V, Download datasheet
IRFP4468 - 190 A , 100 V, Download datasheet
We can decide from above mosfet ratings, still lot of high rating mosfets are there for higher power vehicles like car/bus/truck, but thing is higher power MOSFET need a proper cooling.
IGBT Driver Choosing :
IRS2186 -
Current Sensor choosing :
ACS758 -
Buck Converter choosing :
LTC3638 -
In Progress, Will Update ...!
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