Week-7 Challenge: DC Motor Control
| Program for dc voltage input BJT H-bridge |
| Program out put with out time delay |
| Program out put with time delay |
| refer to the help section of ‘The Four-Quadrant Chopper DC Drive (DC7) block’. Compare it with the H-bridge model. |
| Duty cycle IGBT 1&4 plot | |
| It is seen that duty cycle increases as the vehicle accelerates and decreases when the vehicle decelerates. | |
| Duty cycle IGBT 2&3 plot | |
| The duty cycle decreases as the vehicle accelerates and increases during deceleration of the vehicle. | |
| Armature voltage | |
| The armature voltage of the motor is approximately constant throughout the simulation | |
| Armature current | |
| The current increases as the vehicle accelerates and decreases when the vehicle decelerates. | |
| At T=5s, the speed of the vehicle reduces and the plot shows that the current at that point goes negative. The negative current shows that the motor tends to rotate in the opposite direction in order to decrease the speed of the vehicle according to the drive cycle input. | |
| Motor speed | |
| From the plot it is clearly seen that the motor speed matches the drive cycle input. | |
| Brushless DC motor |
| In this motor, the permanent magnets attach to the rotor. The current-carrying conductors or armature windings are located on the stator. They use electrical commutation to convert electrical energy into mechanical energy. | |||||
| The main design difference between a brushed and brushless motors is the replacement of mechanical commutator with an electric switch circuit. A BLDC Motor is a type of synchronous motor in the sense that the magnetic field generated by the stator and the rotor revolve at the same frequency. | |||||
| Brushless motor does not have any current carrying commutators. The field inside a brushless motor is switched through an amplifier which is triggered by the commutating device like an optical encoder. | |||||
| The layout of a DC brushless motor can vary depending on whether it is in “Out runner” style or “Inrunner” style. | |||||
| Working Principle of Brushless DC motor | |
| BLDC motor works on the principle similar to that of a Brushed DC motor. consequence of reaction force, | |
| the magnet will experience an equal and opposite force. In the BLDC motor, | |
| The current carrying conductor is stationary and the permanent magnet is moving. | |
| When the stator coils get a supply from source, it becomes electromagnet and starts producing the uniform field in the air gap.with trapezoidal shape. permanent magnet rotor, the rotor continues to rotate. | |
| Due to the force of interaction between electromagnet stator and | |
| With the switching of windings as High and Low signals, corresponding winding energized as North and South poles. The permanent magnet rotor with North and South poles align with stator poles which causes the motor to rotate. | |