ClassX Video Lessons Youtube Channel The Engineering Mindset H Bridge Motor Control Basics Explained
Have you ever played with magnets and noticed how they behave? Opposite ends of magnets attract each other, while like ends push away. This is because of their magnetic fields. When electricity flows through a wire, it creates a magnetic field too. If we shape the wire into a coil, this magnetic field becomes stronger and acts like a magnet with a north and south pole. By changing the direction of the electric current, we can switch the poles of this electromagnetic field, turning it on and off as needed.
Unlike electromagnets, permanent magnets always have an active magnetic field. Imagine placing a magnet that can spin freely in the middle of other magnets. By carefully controlling these surrounding magnets, we can make the central magnet rotate. If we use electromagnets around it, we can control the rotation by adjusting the current through each coil. The more coils we have, the more accurately we can control the movement.
To manage these coils effectively, we use something called an H-bridge. Picture a motor with two coils, each connected to four switches. By closing certain switches, we can control the magnetic fields and make the motor’s rotor turn. For example, closing switches one and four will activate coil one, pulling the rotor towards it. Then, closing switches five and eight will continue the rotor’s movement due to the magnetic forces.
Next, by closing switches two and three, we reverse the magnetic field, allowing the rotor to keep turning. Following this, closing switches six and seven moves the rotor further, and finally, closing switches one and four again completes the rotation cycle. This sequence of switching continues, making the rotor spin. If we reverse the order of switching, the rotor will spin in the opposite direction. By changing how fast we switch the coils, we can control the speed of the motor.
The switches in an H-bridge are electronic, not manual. This means we can program them to turn on and off at precise times, giving us exact control over the motor’s movement.
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Gather some wire, a battery, and a nail to create your own electromagnet. Wrap the wire around the nail and connect the ends to the battery. Observe how the nail behaves like a magnet. Try reversing the battery connections and see what happens. This will help you understand how changing the direction of current affects the magnetic field.
Use a compass to map the magnetic field around a permanent magnet. Place the magnet on a piece of paper and move the compass around it, marking the direction the needle points. This activity will help you visualize the invisible magnetic fields and understand how they interact with each other.
Use an online simulator to explore how an H-bridge controls a motor. Experiment with closing different switches and observe how the motor’s direction and speed change. This will give you a hands-on understanding of how electronic switches control motor movement.
Write a simple program using a microcontroller like Arduino to control a small DC motor with an H-bridge. Experiment with different sequences of switch activations to change the motor’s direction and speed. This will enhance your understanding of electronic control in real-world applications.
In groups, discuss various real-world applications of H-bridges and motor control, such as in robotics, electric vehicles, and household appliances. Present your findings to the class. This will help you connect theoretical knowledge with practical uses.
Here’s a sanitized version of the provided YouTube transcript:
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We know that magnets will interact: opposite ends attract while like ends repel. When current flows through a wire, it creates an electromagnetic field. If we wrap the wire into a coil, it generates a larger, stronger electromagnetic field with a north and south pole. We can reverse the polarity by changing the direction of the current, allowing us to turn the magnetic field of the coil on and off by simply allowing or stopping the flow of current.
In contrast, the magnetic field of a permanent magnet is always active. If we place a magnet centrally and allow it to rotate freely, we can use other magnets to facilitate this rotation. Additionally, we can place electromagnets around it and control the rotation by managing the current flowing through each coil. The more coils we use, the more precise the rotation becomes.
A simple way to control the coils is with an H-bridge. If we imagine the motor has two coils, each connected to four switches, we can close switches one and four to polarize coil one, attracting the rotor. Then, we close switches five and eight, causing the rotor to turn due to the attraction and repulsion of the magnetic fields. Next, we close switches two and three, reversing the polarity and allowing the rotor to turn again. We then close switches six and seven to rotate the rotor once more, followed by closing switches one and four to complete the rotation.
This switch sequence continues, causing the rotor to turn. Reversing the sequence will reverse the direction of rotation, and changing the frequency of switching controls the speed. The switches are electronic rather than manual, enabling us to program them to turn on and off with precise timing.
Check out one of the videos on screen now to continue learning about electrical and electronics engineering, and I’ll catch you there for the next lesson. Don’t forget to follow us on Facebook, Twitter, Instagram, LinkedIn, and of course, visit engineeringmindset.com.
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This version maintains the original content while ensuring clarity and professionalism.
Magnetic – Relating to or exhibiting magnetism, the force by which objects attract or repel each other. – The magnetic force between the two magnets was strong enough to hold the paper in place.
Field – A region in which a particular condition prevails, especially one in which a force such as magnetism or gravity is effective. – The magnetic field around the Earth protects us from harmful solar radiation.
Electromagnet – A type of magnet in which the magnetic field is produced by an electric current. – When the switch is turned on, the electromagnet lifts the metal scrap from the conveyor belt.
Coil – A series of loops that has been wound or gathered, often used to create a magnetic field when an electric current passes through it. – The coil in the electric motor generates a magnetic field that causes the rotor to spin.
Rotor – The rotating part of an electrical machine, such as in a motor or generator. – The rotor spins rapidly inside the motor, converting electrical energy into mechanical energy.
Switches – Devices for making and breaking the connection in an electric circuit. – The engineer used switches to control the flow of electricity to different parts of the circuit.
Control – The power to influence or direct the behavior of a system or device. – Engineers use control systems to ensure that machines operate safely and efficiently.
Current – A flow of electric charge, typically measured in amperes. – The current flowing through the wire was strong enough to power the light bulb.
Motor – A machine that converts electrical energy into mechanical energy. – The electric motor in the fan helps to circulate air throughout the room.
Engineering – The application of scientific and mathematical principles to design and build machines, structures, and other items. – Engineering students learn how to design bridges that can withstand strong winds and heavy loads.
