Dc motor speed control using pwm module

A circuit which enables a user to linearly control the speed of a connected motor by rotating an attached potentiometer is called a motor speed controller circuit. A very cool and easy DC motor speed controller circuit could be build using a just a single mosfet, a resistor, and a pot, as shown below:. As can be seen the mosfet is rigged as a source follower or a common drain mode, to learn more about this configuration you may refer to this postwhich discusses a BJT version, nevertheless the working principle remains the same.

In the above DC motor controller design, the pot adjustment creates a varying potential difference across the gate of the mosfet, and the source pin of the mosfet simply follows the value of this potential difference and adjusts the voltage across the motor accordingly. When the gate voltage is around 7V, the source pin will supply the minimum 2V to the motor causing a very slow spin on the motor, and 7V will be available across the source pin when the pot adjustment generates the full 12V across the gate of the mosfet.

Here we can clearly see that the mosfet source pin seems to be "following" the gate and hence the name source follower. This happens because the difference between the gate and the source pin of the mosfet must be always around 5V, in order to enable the mosfet to conduct optimally.

Anyway, the above configuration helps to enforce a smooth speed control on the motor, and the design could be built quite cheaply. When it comes to controlling motor speed uniformly and efficiently, a PWM based controller becomes the ideal option, here we will learn more, regarding a simple circuit to implement this operation. The design of a simple motor speed controller using PWM may be understood as follows: Initially when the circuit is powered, the trigger pin is in a logic low position since the capacitor C1 is not charged.

dc motor speed control using pwm module

The above conditions initiates the oscillation cycle, making the output change to a logic high. A high output now forces the capacitor to charge via D2.

The moment pin 6 triggers, pin 3 and pin 7 reverts to logic low. It is interesting to note that, C1 has two discretely set paths for the process of charging and discharging via the diodes D1, D2 and through the resistance arms set by the pot respectively. It means the sum of the resistances encountered by C1 while charging and discharging remains the same no matter how the pot is set, therefore the wavelength of the out put pulse always remains the same.

However, since the charging or the discharging time periods depends upon the resistance value encountered in their paths, the pot discretely sets the these time periods as per the its adjustments. Since the charge and discharge time periods is directly connected with the output duty cycle, it varies according to the adjustment of the pot, giving form to the intended varying PWM pulses at the output.

The PWM pulses are fed to the gate of a mosfet which reacts and controls the connected motor current in response to the setting of the pot. The current level through the motor decides it speed and thus implements the controlling effect via the pot.

In the above video clip we can see how the IC based design is used for controlling speed of a DC motor. As you may witness, although the bulb works perfectly in response to the PWMs and varies its intensity from minimum glow to maximum low, the motor does not. The motor initially does not respond to the narrow PWMs, rather starts with a jerk after the PWMs are adjusted to significantly higher pulse widths.

This does not mean the circuit has problems, it is because the DC motor armature is held between a pair of magnets tightly. To initiate a start the armature has to jump its rotation across the two poles of the magnet which cannot happen with a slow and gentle movement.

It has to initiate with a thrust. That's exactly why the motor initially requires a higher adjustments for the PWM and once the rotation is initiated the armature gains some kinetic energy and now achieving slower speed becomes feasible through narrower PWMs.

However still, getting the rotation to a barely moving slow status can be impossible because of the same reason as explained above. I tried my best to improve the response and achieve a slowest possible PWM control by making a few modifications in the first diagram as shown below:.I saw several ways to approach this probelm, some are clever, some aren't so smart.

Since i mostly saw "less than optimal" solutions i decided to write this tutorial. First: as long as the motor is "small enough" the cheap and easy solution is to use an H-bridge transistor based control module. The most common devices are the Arduino's "Motor Shield" amazonbanggod or the LN module amazonbanggodwhich is the same concept of a motor shield but its control pins are designed to be more accessible.

Second: this task becomes harder as the motor becomes bigger, at some point the required current can't be managed by the most common h-bridge modules. Moreover most transistor based H-bridge doesn't provide galvanic isolation even if it's theoretically feasilble it's just not a feature of the most common h-bridge modulesand this could also be an issue for your project if it's sensitive to electrical noise.

The first solution is somehow suboptimal but still it's the usual solution that you'll see surfing the web. Several projects use four relay to build a mechanical copy relays are mechanical switches of a transistor H-bridges. Long story short: the four NO connections NO means "normally open", the relay's contacts that don't conduct current when the relay is not active are set up as the conceptual H-bridge switches.

The main issue is that the H-brige requires a precise control of its switches: you must first open a switch and only after a little delay close the other one. If you do the opposite bad things will happen because of an inherent issue. For example: lets pretend that the top lef switch S1 in the image is closed. In this case you can safely close only one of the switches on the right S3 or S4for instance we can assume to have the S4 closed, so the motor is spinning in one direction.

In order to change the spinning direction you have to open S1 and S4 and then close S2 and S3. On the paper is not a big deal, in reality a "little yet not negligible" amount of time is phisically required to open a relay. This means that you need to introduce at least some delay between the operations. You may replay: ok, good to know, but you would have the same issue with transistor based H-bridges, with relay or bigger contactor is only a little more time expensive.

Yes, indeed, it's generally valid for every H-bridge but the transistor module is faster, it use smaller current and it's mostly used paired with a microcontroller maybe with it's own library. Moreover, because of shit happens, the situation could be worse: if you overload a relay you risk to melt its contacts and you might not be able to open it also using the proper command input, so aven a brief mistake can lead to a destructive runaway.

Beside the safety reasons 4 relays are not an optimal solution because only two relays are actually required, so happy days: a better solution actually do exist and it's even cheaper!

If you discard the H-bridge, transistor based or four relay based, and if you take a two relay module amazonbangood and follow this wiring scheme you'll be able to properly control a DC motor in both directions without any risk of short circuit and without spending unnecessary money.

The wiring is quite easy, you only have to connect the power supply plus and minus "at the same side" of the two relays. Fast and easy. With this solution you'll have only four possible outcomes, which are all safe and that won't damage anything. By the way, the module is also optocoupled, therefore the control circuit is two times protected from the power side of the device.

As you can see in the second image it doesn't matter if you don't provide a delay or if you give a wrong input, the motor won't behave in the right way well, you are providing a wrong input, what do you expect? Every possible configuration is ok, and that's not the case with four relays. Funny story: in some forum some people were discussing about adding two more relay to the first four to -somehow.If you are planning on assembling your new robot friend, you will eventually want to learn about controlling DC motors.

It can control both speed and spinning direction of two DC motors. In order to have a complete control over DC motor, we have to control its speed and rotation direction. This can be achieved by combining these two techniques. The speed of a DC motor can be controlled by varying its input voltage. The average voltage is proportional to the width of the pulses known as Duty Cycle. The higher the duty cycle, the greater the average voltage being applied to the dc motor High Speed and the lower the duty cycle, the less the average voltage being applied to the dc motor Low Speed.

A common technique for doing this is to use an H-Bridge. An H-Bridge circuit contains four switches with the motor at the center forming an H-like arrangement. Closing two particular switches at the same time reverses the polarity of the voltage applied to the motor. This causes change in spinning direction of the motor. That means it can individually drive up to two motors making it ideal for building two-wheel robot platforms. The LD motor driver IC actually has two power input pins viz.

Vcc1 is used for driving the internal logic circuitry which should be 5V. From Vcc2 pin the H-Bridge gets its power for driving the motors which can be 4. And they both sink to a common ground named GND. Using the direction control pins, we can control whether the motor spins forward or backward.

L293D Motor Driver and Controlling Motor using PWM – NodeMCU

The IC has two direction control pins for each channel. The below chart illustrates how this is done. The speed control pins viz. Start by connecting power supply to the motors. They are rated for 3 to 9V. So, we will connect external 9V power supply to the Vcc2 pin.

dc motor speed control using pwm module

Connect Vcc1 pin to 5V output on Arduino. Make sure you common all the grounds in the circuit. Note that the Arduino output pins 9 and 3 are both PWM-enabled. The following sketch will give you complete understanding on how to control speed and spinning direction of a DC motor with LD motor driver IC and can serve as the basis for more practical experiments and projects.

The arduino code is pretty straightforward. Finally it turns the motors off. It can control both speed Working of H-Bridge.Ld Pin out and Working. Dc motors speed can be control through various methods. The most popular is by varying the input voltage to the motor.

I am also going to vary the input voltage to dc motor for speed control of dc motor. Input voltage can be varied using a variable resistor. Like in homes we rotate the knob at switch port to control the speed of roof fan. By rotating the knob we vary the input power voltage,current to fan. Digitally controlling the dc motor speed is possible by switching on and off the motor control system. Since we are using a microcontroller nodemcu in our project so we must be switching on and off the system which is controlling the motor.

We are using ld motor driver in our project and our motors are connected across its channels output pins. If we switch on and off the individual channels of ld we can vary the output voltage to motor and hence we can control the motor speed.

Switching on and off the individual channels of ld in a controlled way is an easy task. We can generate a controlled on off signal from nodemcu which can control the motor rotation speed in a desired way. Pwm Pulse width modulation is the name of technique through which control signals can generated from any microcontroller. I am also generating pwm signal from nodemcu for motor speed control. In a pulse width modulation signal output the duty cycle of the signal is controlled.

dc motor speed control using pwm module

Duty cycle is the amount of time the signal is high in a given one period of digital signal. For example period is 2 seconds. Output remains high for 1. Hope it makes sense to you.

When periods are combined it makes frequency. And usually its in kilo or mega Hz. Each ld channel enable pin is supplied the generated pwm signal for controlling the motor rotation speed. Both the ld and nodemcu grounds must be common in order for circuit to work properly. Will start rotating the motor 1 and 2 in clock wise direction.

Will toggle direction and starts rotating motors in anti clock wise direction. In loop function nodemcu is waiting for any request from client. If request is made nodemcu performs the desired function in client request and before closing the request nodemcu replies with the updated status of the dc motor. Future Work I showed you how to control the dc motor speed with nodemcu WiFi module and ld h bridge motor driver.

In my project one can select only three duty cycles.

Speed Control of DC Motor Using PWM

For future you can insert a text field and submit button in web page and accept the custom duty cycle from user through key board. Download the project code. Folder contains the arduino ide. Each and every statement of code is thoroughly explained.

If you have any questions and queries please write them below in the comments section. In this tutorial i am going to teach you how to control speed and direction of dc motor using nodemcu WiFi module and ld motor driver. Nodemcu will serve a web page on your mobile, desktop, laptop or notebook web browser.A DC motor is an electro-mechanical device that converts direct current into mechanical energy by means of rotation of a shaft.

It works on the principle of Lorentz force by which the current carrying conductor in a magnetic field experiences a force hence the conductor moves on the direction of force called Lorentz force. In this chapter, speed control of a DC motor using pulse width modulation PWM technique is described. Generally, a DC motor consists of either an electromagnet or a permanent magnet and a wounded coil known as the armature.

Direct current is applied to the armature by means of a carbon brush or by means of electromagnetic induction. Because of electromagnetic induction, armature moves on the direction of the force. DC motors are widely used in industrial automation, toys and robotics applications. The speed of the DC motor can be controlled either by controlling current to the armature or by using a variable power supply. The fundamental principle of a dc motor is that whenever a current carrying conductor is subjected to a magnetic field, a torque is developed which is directly proportional to the strength of the current passing through the coil and the magnetic field.

The commutator is made segmented to make the torque unidirectional. Each time the current reverses the magnetic field, the direction of force developed is reversed.

An opposition force is required for energy conversion and this opposition force is being given by back emf, the voltage being developed in the armature conductors when they cut the magnetic field. This is the basis of working of a dc motor. Controlling the speed of dc motor can be done by different ways like using a potentiometer and also by a controlled current to the armature. Apart from these techniques, pulse width modulation is the effective way to implement motor speed control.

Pulse width modulation is a digital technique for coding a digital data into a pulsating signal which looks like a square wave. The applications including motor speed control, encoding messages in telecommunication systems, sound synthesis in audio amplifiers. PWM find applications including motor speed control, for encoding messages in telecommunication systems and for controlled switching in switch mode power supplies and for sound synthesis in audio amplifiers etc.

PWM uses a rectangular pulse train whose modulation results in the average value of the pulse sequence. It helps to trigger events based on time.

Capture mode allows us a duration based timing of an event. This circuit gives information regarding the current state of a register which constantly changes its value.

In this case, it is the timer TMR1 register. Compare mode compares values contained in two registers at some point. One of them is the timer TMR1 register. This circuit also allows the user to trigger an external event when a predetermined amount of time has expired.

PWM module generates the rectangular pulses whose duty cycle and frequency can be varied by altering the PWM registers. It usually operates in 3. The solution to the above problems is using motor driving circuit usually known as H-Bridges.The Motor Driver is a module for motors that allows you to control the working speed and direction of two motors simultaneously.

This is designed to provide bidirectional drive currents at voltages from 5 V to 36 V. The DC motor speed in general is directly proportional to the supply voltage, so if reduce the voltage from 9 volts to 4.

dc motor speed control using pwm module

But in practice, for changing the speed of a dc motor we cannot go on changing the supply voltage all the time. The input signals we given to PWM controller might be an analog or digital signal according to the design of the PWM controller. The PWM controller accepts the control signal and adjusts the duty cycle of the PWM signal according to the requirements.

These diagram below shows the waveforms obtained as output at different voltage requirements. Pin 8: VSS, this pin is used to give power supply to connected motors from 5V to 36V maximum depends on Motor connected. Make sure that the Jumpers are preset on the Enable and Enable pins of module, so that motor will be enabled and work at maximum speed.

Make sure to remove the Jumper preset on Enable pins of module, so that we can connect PWM input to this pin and control the speed of motors. If we connect these pins to groundthen the motor will get disabled. You may download this code Arduino Sketch from here.

After uploading the program 2, open the Serial Monitor and send the input values to Arduino.

DC Motor Controller With Two Relay

You can control the speed of the DC motor by sending different values between 0 You must be logged in to post a comment. By Robo India 1. The speed controller PWM for a DC motor works by varying the average voltage supplied to the motor The input signals we given to PWM controller might be an analog or digital signal according to the design of the PWM controller.

These diagram below shows the waveforms obtained as output at different voltage requirements In these waves frequency is same but the ON and OFF times are different. Hardware required S. Pin 3: Output 1, this pin is connected with one terminal of motor. Pin Output 4, this pin is connected with one terminal of motor. Connections with NodeMCU 1. Module Motor terminals — DC motors. Connection with NodeMCU Make sure that the Jumpers are preset on the Enable and Enable pins of module, so that motor will be enabled and work at maximum speed.

Make the connection as shown above. Programming1: Here is the code to run this circuit. Output-1 After uploading the first code you can see both motors get start rotating with maximum speed. Programming2: Here is the code to control the motors with PWM signals. Output-2 After uploading the program 2, open the Serial Monitor and send the input values to Arduino.

Leave a Reply Cancel reply You must be logged in to post a comment. Female to Male Jumper wire.PWM stands for pulse width modulation where we can change pulse width of the signal. In short the duty cycle changes. The frequency of PWM signal remains same.

Hack: modify 20A DC 10-60V PWM Motor Speed Controller and control with Arduino

We can easily generate pwm using arduino. Arduino has inbuilt functions in its library which makes the task easily. These pins can only generate PWM signals as they are connected to the internal timers.

Now the PWM generated at pins 5,6 are of Hz. While other pins generate PWM frequency are Hz. The specifications are for Arduino UNO boards. Now the Arduino compiler have inbuilt function named as analogWrite. To generate PWM using arduino two parameters are passed during this function call. Hence we are using the NPN Transistor as a switch. Current starts flowing in the collector to base direction. The diode is used for a safety purpose so that the reverse direction current is obstructed.

There is no connection between the VCC and ground. Hence the Motor does not conduct. Hence higher the duty cycle higher times the transistor remain in ON state and higher the speed. Thank You for referring the guide. Please feel free to comment or contact us anytime at elexfocus gmail.

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Dc motor speed and direction control over WiFi using Nodemcu esp8266 Wifi module

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