DC Motor & Its Control
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The document discusses the parts, operation, types, and control of DC motors. It describes the basic components of a DC motor including the yoke, poles, field winding, armature winding, and commutator. It explains that DC motors convert electrical energy to mechanical energy using the interaction of magnetic fields from the stator and rotor. The document also discusses speed control using pulse width modulation to vary the voltage applied to the motor, and torque control using current variation. It covers motor parameters, electrical analysis, switching circuits, and motion profiling considerations like jerk and vibration analysis.
DC Motor & Its Control
- 1. --Rishabh Shukla DC MOTOR & ITS CONTROL
- 2. CONTENTS:- 1. Parts of Motor. 2. Basic of Operation 3. Types of AC Motor 4. Types of DC Motor 5. Design Parameters 6. Electrical Analysis 7. Switching Circuit 8. Speed Control 9. Torque Control 10. Motion Profile
- 3. PARTS OF DC MOTOR:- 1. Yoke 2. Pole 3. Field Winding 4. Armature Winding 5. Commutator &
- 4. 1. Converts direct current(electrical energy) into mechanical energy. 2. Extensively used in Industry & vital for Engineers. *TWO EQUAL AND OPP FORCE CONSTITUTE TORQUE* BASIC OPERATION:-
- 5. Parameters Synchronous Induction Slip No ~Interlocking Yes~ Phase difference Excitation Double (Armature+Field) Single Application Timer/ Tape Recorders 90% of Industrial motors Principle Interaction of B Field of Stator & Rotor. I flows in stator— induces B Field. Types of AC Motor :-
- 6. Parameters Brush Brushless Commutation Mechanism Mechanical using Brush Via Electronic Switching Circuit Mechanical Friction Yes No Arcing/ Sparks Yes No Max Speed Limited by Brush Greater Thermal Characteristics Difficult (Electromagnet is on Rotor) Improved thermal characteristics. Motion Precision Less More System Weight More Less Types of DC Motor On the basis of Commutation:- *THE ACT OF CHANGING DIRECTION OF CURRENT IS CALLED COMMUTATION*
- 7. *DESIGN PARAMETERS:- Parameters Definition 1 Stall Torque Is the torque produced by the motor when at standstill. 2 Nominal Torque Is the torque generated for operation at nominal voltage and nominal current at temp of 25 degree C 3 Speed/Torque Gradient Indicator of Motor Performance. Smaller the value more powerful the motor. It is quotient of no load speed and ideal stall torque. 4 Mechanical Time const Time required for rotor to accelerate form standstill to 63% of its no load speed 5 Nominal Voltage Is the applied voltage between two powered phases in bolck commutation mode 6 Thermal time constant Typical reaction time for a temperature change of winding and motor
- 8. Electrical Analysis of a DC Motor Where, P = no of poles φ = flux per pole Z= No. of conductors A = No. of parallel paths and N is the speed of the DC Motor. Eb is proportional to speed ‘N’. So when the speed of the motor is reduced by the application of load, Eb decreases. means E − Eb increases. Due to this increased voltage difference, armature current will increase and therefore torque and hence speed increases. Thus a DC Motor is capable of maintaining the same speed under variable load. As a result we need to use a starter for starting a DC Motor. NEED OF STARTERS:-
- 9. 1. Based on the position of the motor (identified using feedback sensor) two of the three electrical windings are energized at a time. 2. External circuit should be able to meet the current requirement of motor. Switching Action cause the Stator’s B to rotate. --- Bidirectional Currents are produced. A total of six switches are needed for one BLDC motor. *SWITCHING CIRCUIT:-
- 10. The Motor Speed depends on the amplitude of applied voltage, which is adjusted using Pulse Width Modulation (PWM) By controlling the duty cycle of the PWM signal . The amplitude of the applied voltage can be controlled, which in turn will control the speed of the motor. *SPEED CONTROL:-
- 11. * MAXIMUM PERMISSIBLE SPEED :- •Max Speed is limited by the commutation system •At very high speed, commutators and brush wear more rapidly, causing reduce in life of motor. •At high speed arcing is more pronounced. Mn- Rated Torque. Tw- Thermal time constant
- 12. Where, P is no of poles, φ is flux per pole, Z is no. of conductors, A is no. of parallel paths, and N is the speed of the D.C. motor. *TORQUE CONTROL:-
- 13. 1. TRIANGULAR:- 2. TRAPEZOIDAL:- More rapid the change in acceleration, the more powerful the vibrations will be *MOTION CONTROL:- JERK= CHANGE IN ACCLERATION TIME
- 14. 3. S -Type:- Induced vibration for S curve and trapezoidal mode. 4. VIBRATION IN SYSTEM:- *VIBRATION ANALYSIS:-
- 15. *CHALLENGES:- •TO KNOW THE KEY REQUIREMENTS OF FORCES/ TORQUES and VELOCITIES (SPEED OF ROTATION)?? •HOW LONG THEY MUST BE APPLIED?? •DESIGN A DRIVING MECHANISM BY CALCULATING THE MOMENT OF INERTIA OF ROTATING LOAD. •GEARHEAD DESING •CHOOSE BETWEEN AVALIABLE MOTORS. •SENSOR CONTOLLER •COST CONSIDERATION
- 16. *REFERNECE:- 1. Maxon Motros 2. Electrical For you 3. Wikipedia