Tag: DC motors
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Techniques used in Stopping DC Motors
Stopping of a motor is actually a form of speed control. Methods used to stop DC motors are in a way similar to speed control techniques. To stop a motor, you must accelerate in the direction opposite to that in which it is moving. There are two techniques of electrically stopping a DC motor, namely:…
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How to Perform a Brake Test on a DC Motor
Testing is usually performed on DC machines to establish efficiency and power losses. A brake test is a direct technique that involves applying a brake to a water-cooled pulley mounted on the motor shaft as demonstrated in Figure 1.0. This brake test method is typically used on small motors. The brake band is fixed with…
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DC Motor Power Op-amp Speed Controller
Let’s consider the functional diagram below: The D/A converter outputs a voltage directly related to the potentiometer position. However, the D/A converter’s output current is limited and not enough to drive a motor. A power operational amplifier (op-amp) circuit, configured as a noninverting amplifier can drive the motor at the higher currents required. In effect,…
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Features of Stepper Motors & How they are applied in Industrial Control
A stepper motor is a permanent magnet or variable reluctance DC motor that has the following characteristics: It is able to rotate in both directions It can move in precise angular increments It can sustain holding torque at zero speed Can be controlled with digital circuits Stepper motor moves in accurate angular increments, known as…
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Factors to consider when selecting a Motor for a particular application
When selecting a motor for a specific industrial application, there are several factors and specifications that you should consider. We look at these factors that will guide you when choosing the appropriate motor for your industrial use. The following are some of the key questions or factors that you should consider when choosing the suitable…
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Pulse Width Modulation (PWM) Speed Control of a DC motor
We can control the speed of a motor using an open loop control or closed loop control strategy. The open loop control is the simplest form of motor control; here we simply set the drive voltage value and the motor characteristics and the load determines the operating speed & torque. But you will find that…
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Speed Control of a DC Compound Motor
A compound motor is a combination of a series and a shunt-wound motor. The Speed-torque characteristics for a compound motor Speed Control of a DC Compound Motor Speed is controlled by variable resistors in the shunt field and armature circuit. The series winding may be arranged that it aids the shunt field (cumulative compound) or…
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DC Shunt Motor Speed Control
In the shunt motor, the motor winding is in parallel with the armature. From the figure above, the supply current I = Ia + If . Unlike a series motor, if the load is removed from the motor, only the armature current will decrease, the field remaining at the same strength. Therefore the motor will…
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Speed Control of a DC Series Motor
The dc series motor has its windings and armature connected in series across the supply. From the figure above, the armature current Ia also supplies the field, hence when Ia is large on starting for example, the magnetic field will be strong, and the torque will be high. As the machine accelerates, the torque, armature…
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The Essential Components of An Electric Drive
Power electronics deals with the applications of solid-state electronics for the control and conversion of electric power. The conversion techniques require switching power semiconductor devices ON and OFF. The block diagram below shows the essential components of an electric drive controlled by a power semiconductor converter. The converter regulates the flow of power from the…