What is DC motor speed control?

What is DC motor speed control?

Often we want to control the speed of a DC motor on demand. This intentional change of drive speed is known as speed control of a DC motor. Speed control of a DC motor is either done manually by the operator or by means of an automatic control device.

How the speed of a DC motor can be increased or decreased?

The speed of rotation of an electric motor can be varied based on the following factors: Magnetic flux – By decreasing the flux, the speed of the motor can be increased. The flux can be changed by changing the current with a shunt field rheostat. This increased torque causes the dc motor to increase in speed.

What limits the speed of a DC motor?

DC controls adjust speed by varying the voltage sent to the motor (this differs from AC motor controls which adjust the line frequency to the motor). Typical no load or synchronous speeds for an AC fractional horsepower motor are 1800 or 3600 rpm, and 1000-5000 rpm for DC fractional hp motors.

When the speed of dc motor is increased?

Complete answer: From the equation. (3) we can say, speed is inversely proportional to armature current. Thus, when the speed of the dc motor is increased, the armature current will decrease.

How do you control a dc motor?

Thus, the speed of a DC motor can control in three ways:

1. By varying the flux, and by varying the current through field winding.
2. By varying the armature voltage, and the armature resistance.
3. Through the supply voltage.

Why does current increase when DC motor is increased?

Why does armature current increase when load on the DC motor increase? When the load increases the motor slows down. This reduces the counter EMF. This allows a higher current to flow.

What will happen with the increases in speed of a DC motor?

What will happen, with the increase in speed of a DC motor? a) Back emf increase but line current falls. So, with the increase in speed, the back emf also increases. Therefore, armature current is also decreased, in case of series motor, armature current is equal to the line or load current.

What are the factors affecting speed of dc motor?

Factors Affecting The Speed Of A D.C. Motor

• The flux Φ
• The voltage across the armature.
• The applied voltage V.

When do you need to control the speed of a DC motor?

Often we want to control the speed of a DC motor on demand. This intentional change of drive speed is known as speed control of a DC motor. Speed control of a DC motor is either done manually by the operator or by means of an automatic control device.

How is the speed of a DC shunt motor controlled?

Armature Resistance Control Method for DC Shunt Motor With this method, the speed of the DC motor can be controlled by controlling the armature resistance to control the voltage drop across the armature. This method also uses a variable resistor in series with the armature.

How is the speed of a DC generator controlled?

In the above picture, M is the main motor where its speed is to be regulated and G corresponds to an individually excited DC generator where this is driven by using a three-phase motor and it may be of either synchronous or induction motor. This pattern of DC generator and AC driven motor combination is termed as M-G set.

How does Ward Leonard’s DC motor speed control circuit work?

The Ward Leonard technique of DC motor speed control circuit is shown as follows: In the above picture, M is the main motor where its speed is to be regulated and G corresponds to an individually excited DC generator where this is driven by using a three-phase motor and it may be of either synchronous or induction motor.