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DC Motor Speed Control Circuit: Find a suitable speed regulation system

Are you in search of the best DC motor speed control circuit for your project? Please sit back and relax. We have the answer for you. First, finding the best DC motor speed control circuit is not a walk in the park. Therefore, below is a highlight of some of the techniques used. Read this piece until the end to ensure that you get everything you wish to know about the DC motor speed control circuit.

What is DC Motor?

A direct current (DC) motor is an electronic gadget that converts electrical energy to mechanical energy in most household appliances and other motor applications. Additionally, it uses a magnetic field that builds from the electrical currents created. Moreover, the output speed and motor torque rely on the design of the motor and the electrical input. Therefore, the motor turns fast when working on a light load.

The Importance of DC Motor Speed Control

Acceleration control in a DC motor control circuit is essential since it shows an effect on the acceleration of motor rotation. Besides, when drilling, each material has a rotational speed that varies depending on the drill size. Therefore, the result directly influences the machine’s functionality, hence necessary for the operation and result.

Moreover, when installing the pump, a variation occurs in the output rate. Therefore, a conveyor belt is crucial to sync the operating speed. In addition, these factors may appear in any way, depending on the acceleration of the device. Due to this, you should consider the DC motor acceleration and note several types of acceleration regulation methods. 

Speed Control techniques of DC motor circuit

Different DC motor speed control circuits use different components and technologies. Therefore, below are some of the principles and components.

  • Armature control method
  • Field control method

Armature Control Method

Armature Resistance Control

You will find this technique primarily used in regulating resistance with a series link to the DC motor supply. Therefore, you can ignore the power decrease in the DC series. Additionally, this regulating resistance can last for a period hence decreasing the speed during light loading instances. Moreover, this technique is cheap for recurrent torque and can drive trains, cranes, electric motors, and other electronic devices.

Shunted controlled resistance

Rheostat in series

Rheostat in series

In this technique, the rheostat is in series and shutting links with the armature. Therefore, you will notice a difference in the amount of power that the armature receives. Moreover, the voltage level differs by altering the rheostat in series. However,  the difference in excitation power mainly occurs if you adjust the rheostat in the shunt. 

This DC motor speed control method is very cheap due to minor power loss during speed control resistances. Therefore, you can regulate the speed you may wish but should not go beyond the average level.

Voltage Control Method 

You can enhance the acceleration of your DC motor by using an independent varied power voltage through the power supply to the monitor. Besides, this technique is expensive and not widely used.

Field-controlled Method

Field Diverter Method

DC motor speed control circuit

DC motor speed control circuit

In this technique, a DC motor speed control circuit uses a diverter. Additionally, you can reduce the flow rate through the field by shifting some motor power sections. Therefore, if the resistance from the diverter is less, the current flow becomes less. Moreover, this technique works better than the average speed range. Also, it can work on electric devices where the motor speed upsurges due to a decline in load.

Tapped Field Control

Tapped magnetic flux

Tapped magnetic flux

When the flux reduces, the speed increases also, and you can achieve this by minimizing the field twisting turns at a point where the current flow occurs. You will find this technique mostly on electric tractions.

Controlling the speed of a DC shunt Motor Circuit

It has two categories which include:

  • Field controlled method
  • Armature controlled method

Field controlled technique for DC shunt motor

Magnetic flux

Magnetic flux

Under this technique, the magnetic flow results from field twisting changes to vary the motor speed. Therefore, you can achieve this by installing a variable resistor.

Initially, the rated current will flow through the field twisting if the variable resistor remains at its lowest point. Additionally, the rated voltage supply influences this also, and therefore, the speed remains normal. Moreover, when the speed increases slowly, the current on the field windings gradually reduces. Therefore, this will decrease the flux generated.  Therefore, the acceleration of the DC motor may go beyond its average rating.

Armature Resistance Regulator Using a Variable Resistor

Armature Resistance control

Armature Resistance control

This method uses a variable resistor to control the acceleration of the motor. In addition, you can achieve this by restricting the resistance on the armature hence preventing the voltage fluctuation on the armature.

Moreover, when the resistor attains its least point, the armature current is also at the set rate. Alternatively, if the resistance slowly increases, the voltage on the armature reduces, leading to a decline in the motor speed.

Armature Voltage Regulator Techniques

DC generator

DC generator

The Ward Leonard DC, motor speed control circuit is a technique that has a primary motor that regulates the speed. Additionally, it has a DC generator that drives the speed using a three-stage DC motor. Moreover, this motor can be either induction or an asynchronous motor like the 3-phase squirrel-cage motor. Therefore, this kind of AC driven motor and DC generator combination bears the brand name M-G.

Moreover, generator voltage will change when you alter its field current. Besides, this voltage varies as it goes through the armature part of the motor, then to the generator. Therefore, to maintain the field flow constant in the motor, the current at the motor force should remain constant also. Again, after setting the motor acceleration at a certain level, the motor current must remain at the same level.

Moreover, the field current generated is not uniform for the voltage level to change from zero to the set level. Therefore, the speed control matches the set currently with the continuous field flow of the motor until it reaches the target speed. Since the power is the product of torque and speed, an increase in load current causes an increase in speed.

Finally, in the Ward Leonard DC motor speed control circuit technique, the adjustable power drive is achieved when the speed level is lowest to the base speed level. Additionally, you can accomplish the constant value of the motor drive voltage and torque through the same. Nevertheless, the field flow regulation is essential when the acceleration level exceeds the base acceleration level.


  • Firstly, it is the most smooth speed control technique with a wide range from zero to the normal speed of the DC motor.
  • Secondly, the motor can run at a constant speed
  • Additionally, the speed regulation of this DC motor is superb
  • Moreover, the speed control is easily achievable in all directions of rotation of the motor
  • Finally, it has an in-built regenerative braking characteristic


  • Firstly, when the system is lightly loaded, it does not provide sufficient efficiency.
  • Secondly, it is large, and weight hence requires more floor space
  • Additionally, it needs frequent maintenance
  • Moreover, it produces a lot of noise
  • Finally, it is costly

Final words

Without a doubt, I believe this piece has the answers to all your questions on the DC motor speed control circuit. Moreover, it is upon you to decide on which technique you prefer for your project. Nevertheless, all the above techniques are a great help in the correct application. Finally, you can share this piece with your friends on social media platforms such as Facebook, Pinterest, etc. Also, you can visit our site and leave a comment.