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# System prepended metadata

title: PPT_CHAPTER_7

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# PPT_CHAPTER_7
# Controllers

#### Slide_1:Motor Controller

* DC motor is a device that converts direct current into mechanical work. 
* It works on the principle of Lorentz law, which states that “the current carrying conductor placed in a magnetic field experience a force”. 
* The motor controller is an electronic circuit that is responsible for controlling the speed and direction of the motor.

#### Slide_2 Principle of Motor Rotation 
 
 ![](https://i.imgur.com/h6s117q.png)

![](https://i.imgur.com/cqe0uit.png)

#### Slide_2: BLDC Motor Control

3Phase H-Bridge
* A standard controller has 3 bi-directional outputs which are operated by a logic circuit
* The three two-way outputs are operated by switches. 
* Such switches need to be able to turn on and off very quickly to spin the motor.
![](https://i.imgur.com/W9Z4HB1.png)

PWM Technique
* It is an effective method for adjusting the amount of power delivered to the load.
* This technique allows smooth speed variation without reducing the starting torque and eliminates harmonics.
* PWM is an entirely different approach to controlling the speed of a DC motor. 
* Power is supplied to the motor in square wave of constant voltage but varying pulse-width or duty cycle. 

![](https://i.imgur.com/TyRhoTe.png)

#### Slide_3: Sensorless 

* Back EMF control method
It is based on the fact that only two phases of a DC Brushless motor are coupled at a time, so that a third phase of the Back-EMF voltage can be sensed. 
![](https://i.imgur.com/hgtr1eD.png)

#### Slide_4: Sensor based controller
* Hall effect sensor-based controllers

![](https://i.imgur.com/eVcnZlM.png)

#### Slide_5: Working of Hall Effect Sensor
![](https://i.imgur.com/pqSwM63.png)

#### Slide_6: Working of Hall Effect Sensor(Cont)
* Commutation Table

![](https://i.imgur.com/CyVBGDE.jpg)

#### Slide_7: Types of Hall Sensor
* Analogue sensor
The analogue sensor is composed of a voltage regulator, a Hall Element and an amplifier.
* Digital sensor
The digital output sensors provide just two output states, either “ON” or “OFF”.

#### Slide_8: Advantages and Disadvantages of Hall Effect Sensors
Advantages
• Low cost.
• Can be operated at higher frequencies.
• Not be affected by environmental contaminants.
• Can measure a wide range of magnetic fields.

Disadvantages
• Low accuracy.

#### Slide_9: Features in a modern day BLDC motor controller

* Intelligence with powerful microprocessor.
* Electronic reversing.
* Voltage monitoring on 3 motor phases, bus, and power supply.
* Voltage monitoring on voltage source 12V and 5V.
* Current sense on all 3 motor phases.
* Current control loop.
* Hardware over current protection.
* Hardware over voltage protection. 
* Configurable limit for motor current and battery current.
* Battery protection
* Waterproof connectors for small signal.
* Thermal protection
* Controller can do auto Identification angle for different degrees of hall sensors.

