Applications of MOSFET
Published: 2021-06-14 06:25:56

The MOSFET is used in a variety of electrical and electronic projects that are created using a variety of electrical and electronic components. We have provided some examples of projects to help you grasp this concept.

#1. MOSFET as a switch:

An N-channel MOSFET is used to switch the lamp ON and OFF in this circuit, which is using enhanced mode. When a positive voltage is applied to the MOSFET's gate, the lamp turns on (VGS =+v), when removed the device turns off (VGS=0). If the lamp's resistive load was to be replaced with an inductive load and the load was to be protected by a relay or diode. It is a very simple circuit for switching a resistive load, such as LEDs or a lamp, in the above circuit. However, when using MOSFETs to switch either an inductive or capacitive load, MOSFET applications must be protected. You should also have a look at this detailed lecture on [Transistor as a switch](https://www.theengineeringprojects.com/2019/10/transistor-as-a-switch.html). The MOSFET will be damaged if we do not provide the necessary protection. To function as an analogue switching device, the MOSFET must be switched between its cutoff and saturation regions, where VGS =0 and VGS =+v, respectively
![Alt Text](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/e2xjvio41fxa6j9f1nj7.jpg)

#2. MOSFET-based Auto Intensity Control of Street Lights:

The majority of lights used on highways nowadays are High-Intensity Discharge lamps (HID), which have a high energy consumption. Because the intensity of the light cannot be adjusted to meet the requirements, an alternative lighting system, such as LEDs, could be used. This system is designed to overcome the disadvantages of HID lamps in today's world.

The goal of this project is to use a microprocessor and clock pulses to [control the street lights](https://www.theengineeringprojects.com/2016/09/automatic-street-light-project-proteus.html) on highways automatically. The MOSFET is used to switch the lamps according to the requirements in this project. The proposed system makes use of a Raspberry Pi board, which is a new development board that includes a processor. In this case, we can use LEDs instead of HID lamps, which are connected to the processor via a MOSFET. The microcontroller switches the MOSFET to illuminate the light with bright intensity after releasing the respective duty cycles.

#3. High Voltage Based on a Marx Generator MOSFET:

These are a type of semiconductor that can be used in a wide range. The main goal of this project is to create a circuit that uses the [Marx generator](https://hibp.ecse.rpi.edu/~leij/febetron/marx.html) principle to deliver an output voltage that is roughly triple that of the input voltage. It is designed to generate high-voltage pulses by charging a number of capacitors in parallel during the on period and then connecting them in series during the off period to generate a higher voltage. If the applied input voltage is around 12 volts DC, the output voltage will be around 36 volts DC.

Due to the voltage drop in the circuit, this system uses a 555 timer in a stable mode to deliver clock pulses to charge the parallel capacitors during on time and to bring the capacitors in series during off time through MOSFET switches; as a result, the voltage developed is approximately triple the input voltage but a little less than 36v. 

#4. Preset Speed Control of a BLDC Motor Using an EEPROM:

The BLDC motor's speed control is critical in industries, as it is required for a variety of applications such as drilling, spinning, and elevator systems. The duty cycle of the BLDC motor is varied in this project to control the speed of the motor.

The main goal would be to run a BLDC motor at a specific speed while maintaining a predetermined voltage. As a result, the motor can either remain operational or be restarted to run at the same speed as before using data stored in an [EEPROM](https://whatis.techtarget.com/definition/EEPROM-electrically-erasable-programmable-read-only-memory).

The duty cycles (PWM Pulses) from a microcontroller are varied according to the program to control the speed of the DC motor. In order to control the speed of the DC motor, the microcontroller receives the percentage of duty cycles stored in the EEPROM from inbuilt switch commands and delivers the desired output to switch the driver IC. If the power supply is lost, the EEPROM stores the information to keep the motor running at the same speed it was before the power supply was lost.

#5. Intensity-controlled street lights:

A (light dependent resistor) [LDR based light detector](https://www.theengineeringprojects.com/2021/04/automatic-light-detector-using-ldr-in-proteus.html) could be used. In the current system, highway lighting is mostly done with High-Intensity Discharge lamps (HID), which have high energy consumption and no specialized mechanism to turn on the highway light in the evening and turn it off in the morning.

Because the intensity of the light cannot be adjusted to meet the requirements, an alternative lighting system, such as LEDs, must be used. This system is designed to overcome the disadvantages of HID lamps in today's world.

This system demonstrates the use of LEDs (light-emitting diodes) as a light source and how to control the intensity of the light based on the requirements. When compared to traditional HID lamps, LEDs use less energy and have a longer lifespan.

The most important and intriguing feature is that its intensity can be adjusted to meet individual needs during non-peak hours, which is not possible with HID lamps. The light is detected using a light sensing device called LDR (Light Dependent Resistance). Its resistance decreases dramatically as the amount of daylight increases, which serves as an input signal to the controller.

A street light is made up of a grouping of LEDs. The microcontroller has programmable instructions that control the brightness of the lights using PWM (pulse width modulation) signals.

The intensity of light is maintained at a high level during peak hours, and as traffic on the roads decreases late at night, the intensity gradually decreases until morning. Finally, at 6 a.m., the lights are turned off completely until 6 p.m., when they are turned back on. As a result, the procedure repeats itself.

#6. SVPWM (Space Vector Pulse Width Modulation):

SVPWM is a non-profit organization that helps people (Space Vector Pulse Width Modulation)

The Space Vector PWM technique is a sophisticated method of controlling AC motors by generating a fundamental sine wave that provides a pure voltage to the motor with lower total harmonic distortion. Due to the asymmetrical nature of the PWM switching characteristics, this method outperforms the old technique of using SPWM to control an AC motor with high harmonic distortion.

This system generates DC power from single-phase AC after rectification, which is then fed to a 3-phase inverter with six MOSFETs. A pair of MOSFETs is used for each phase, resulting in three pairs of MOSFETs being switched at different intervals of time to produce a three-phase supply to control the motor's speed. This circuit also indicates any faults in the control circuit with a light.

As a result, we've covered all of the different types of MOSFET applications. Finally, we'll point out that MOSFETs require a high voltage, whereas transistors require a low voltage and current. The driving requirement of a MOSFET is significantly lower than that of a BJT.