ClassX Video Lessons Youtube Channel The Engineering Mindset Power Inverters Explained – How do they work working principle IGBT
Hello everyone, Paul here from The Engineering Mindset. In this article, we will delve into the fascinating world of power inverters, exploring their basic functioning and common applications. It’s important to note that working with electricity can be hazardous, so ensure you are qualified and competent before undertaking any electrical work.
A typical power inverter is a device that converts direct current (DC) into alternating current (AC). It features red and black DC terminals on the back and AC electrical outlets on the front. This conversion is crucial because most household appliances are designed to operate on AC power, which is supplied by electrical outlets. However, energy sources like solar panels and batteries generate DC electricity. Therefore, to power our devices using renewable sources or battery banks, we need to convert DC into AC using an inverter.
To grasp how an inverter functions, it’s essential to understand some electricity fundamentals. Inside a copper wire, electrons move randomly among copper atoms. By applying a voltage difference across the wire, we can direct these electrons to flow in a single direction, creating an electric current. This flow of electrons is known as DC electricity, which moves consistently from one terminal to another, similar to a river flowing in one direction.
Conversely, AC electricity involves electrons flowing back and forth, akin to the ebb and flow of ocean tides. This alternating movement is why it’s called alternating current. In a basic generator, coils of wire and a rotating magnet create this alternating flow, resulting in a sine wave pattern.
Power inverters use electronic switches called Insulated Gate Bipolar Transistors (IGBTs) to convert DC into AC. These switches are controlled by a controller, which opens and closes them rapidly in pairs to manage the flow of electricity. By directing the electricity through different paths and controlling the duration of flow, the inverter produces AC electricity from a DC source.
To achieve this, four switches or IGBTs are connected across a load, such as a lamp. By closing switches one and four, current flows in one direction. Opening these and closing switches two and three reverses the current direction. This process is automated by the controller to ensure continuous operation.
If the input voltage is low, the output will also be low. To achieve the necessary 120 volts or 230 volts for household appliances, a transformer is used to step up the voltage. Initially, this conversion results in a square wave pattern, which, while technically AC, doesn’t resemble the smooth sine wave of typical AC electricity.
To improve this, pulse width modulation (PWM) is employed. By rapidly opening and closing the switches multiple times per cycle, the inverter can control the current flow, creating a waveform that closely mimics a sine wave. Adjusting the duration the switches remain closed allows for outputting different voltages as needed.
Most homes use single-phase electricity, while larger commercial buildings and some homes, particularly in Europe, utilize three-phase electricity. In North America, split-phase electricity is common, providing two hot wires and a neutral. Three-phase electricity involves connecting to three phases that are 120 degrees apart, delivering more power by filling gaps between sine wave peaks. Larger applications require a three-phase inverter to convert clean DC into three-phase AC.
That’s it for this overview of power inverters! For further learning, explore additional resources and videos available on The Engineering Mindset. Stay connected with us on social media for more insights and information.
Engage with an online simulation that allows you to manipulate the components of a power inverter. Experiment with different configurations of Insulated Gate Bipolar Transistors (IGBTs) to see how they affect the conversion of DC to AC. This hands-on activity will help you visualize the internal workings of an inverter and understand the role of electronic switches.
Form small groups and discuss various real-world applications of power inverters, such as in renewable energy systems, electric vehicles, and uninterruptible power supplies (UPS). Share insights on how inverters are crucial in these applications and explore potential future developments in inverter technology.
Participate in a guided workshop where you will construct a simple power inverter using basic electronic components. This project will reinforce your understanding of inverter design and operation. Ensure you follow safety guidelines and work under supervision if necessary.
Analyze a case study focusing on the efficiency and design of a specific power inverter model. Evaluate the design choices made to improve waveform quality and voltage transformation. Discuss how these choices impact the inverter’s performance and efficiency in different applications.
Conduct research on the latest advancements in inverter technology, such as smart inverters and their role in smart grids. Prepare a presentation to share your findings with the class, highlighting how these technologies are shaping the future of energy conversion and distribution.
Sure! Here’s a sanitized version of the provided YouTube transcript:
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Hello everyone, Paul here from The Engineering Mindset. In this video, we will explore power inverters to understand the basics of how they work and where we use them. Please remember that electricity can be dangerous and potentially fatal, so you should be qualified and competent to carry out any electrical work.
A typical inverter looks something like this: it has red and black DC terminals on the back and AC electrical outlets on the front. This is because there are two types of electricity: AC (alternating current) and DC (direct current). An inverter is used to convert DC into AC. We can also convert AC into DC using a rectifier, but we will cover that in a separate video, and I’ll leave some links in the description below for that.
The appliances in our homes are designed to run off an AC supply, which they receive from electrical outlets that provide AC electricity. However, electricity produced by sources such as solar panels and batteries is DC. Therefore, if we want to power our electrical devices from renewable sources, battery banks, or even our cars, we need to convert DC into AC electricity, which is done with an inverter.
To understand how an inverter works, we first need to grasp some fundamentals of electricity. Inside a copper wire, we find copper atoms that contain electrons. These electrons can move to other atoms and are known as free electrons. They move randomly in all directions, but we need them to flow in the same direction, which we achieve by applying a voltage difference across the wire. The voltage acts like pressure that pushes the electrons. When we connect a wire to the positive and negative terminals of a battery, we complete the circuit, and electrons begin to flow. This flow of electrons is called current.
The electricity from solar panels and batteries is known as DC electricity because it flows in a single direction, from one terminal to the other. If we reverse the battery, the electrons flow in the opposite direction. You can think of DC electricity like a river with water flowing in one direction.
In these animations, I use electron flow, which is from negative to positive, but you might be more familiar with conventional current, which is from positive to negative. Electron flow is what actually occurs, while conventional current was the original theory and is still widely taught today.
When we observe the electrical waveform for DC on an oscilloscope, we see a flat line at the maximum voltage in the positive region. If we cut the power, the line drops to zero. If we turn the power on and off repeatedly, we get a square wave pattern between zero and maximum. If we adjust the switch to open and close over different lengths of time, we create a pulsating pattern.
With AC electricity, the electrons flow forwards and backwards constantly. This is how it gets its name, as the current alternates in direction. You can think of this type of electricity like the tide of the sea, which flows in and out between high and low tide.
Inside a basic generator, we find coils of wire and a rotating magnet at the center. The magnet has a north and south pole. As the magnet rotates past the coils, it pushes and pulls the electrons within the copper coils and through the connected wires. The magnetic field of the magnet varies in intensity, causing the coil to experience a change in the magnetic field. This results in a wave pattern known as a sine wave.
The voltage in AC electricity is not constant; it moves from zero to its peak, back to zero, then to the negative peak, and finally back to zero again. Frequency refers to how many times this AC sine wave repeats per second. In North America and some other regions, we have 60 Hertz electricity, meaning the sine wave repeats 60 times per second. In most other parts of the world, we find 50 Hertz electricity, where the sine wave repeats 50 times per second.
The inverter consists of electronic switches known as IGBTs (Insulated Gate Bipolar Transistors). The opening and closing of these switches is controlled by a controller, allowing them to open and close rapidly in pairs to control the flow of electricity. By controlling the path the electricity takes and how long it flows in different paths, we can produce AC electricity from a DC source.
To produce AC electricity, we can connect four switches or IGBTs across our load, such as a lamp. If we close switches one and four, the current flows in one direction. If we then open those and close switches two and three, we get current flowing in the opposite direction. This process can be automated by the controller to repeat continuously.
If we have a low voltage input, we will also have a low voltage output. To reach the required 120 volts or 230 volts to power our appliances, we will need a transformer to step up the voltage to a useful level. When we observe this through an oscilloscope, we see a square wave in the positive and negative regions. While this is theoretically AC because it reverses direction, it doesn’t resemble a smooth AC sine wave.
To improve this, we can use pulse width modulation (PWM). By rapidly opening and closing the switches multiple times per cycle in a pulsating pattern, we can control the amount of current flowing per segment, resulting in a sine wave. The more segments we have, the closer it mimics a smooth wave. We can control the output voltage by adjusting how long the switches are closed, allowing us to output different voltages as needed.
We also have single-phase and three-phase AC electricity. Most homes use single-phase electricity, while larger commercial buildings and some homes, especially in Europe, use three-phase electricity. In North America, homes often use split-phase electricity, which provides two hot wires and a neutral.
With three-phase electricity, we connect to three phases that are 120 degrees apart. This allows us to deliver more power by filling in the gaps between the peaks of the sine waves. Larger applications require a three-phase inverter, which uses a rectified three-phase AC supply to create a smooth DC waveform. We then use a three-phase inverter to convert this clean DC into three-phase AC.
That’s it for this video! To continue your learning, check out one of the videos on screen now. Don’t forget to follow us on social media and visit The Engineering Mindset for more information.
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This version removes any informal language and ensures clarity while maintaining the educational content.
Power – The rate at which energy is transferred or converted per unit time in a system. – The power output of the solar panel was calculated to determine its efficiency in converting sunlight into electricity.
Inverter – A device that converts direct current (DC) into alternating current (AC). – The inverter is crucial in solar power systems to convert the DC electricity generated by solar panels into AC electricity used by household appliances.
Electricity – A form of energy resulting from the existence of charged particles, such as electrons or protons, and used for power. – Understanding the principles of electricity is fundamental for electrical engineering students when designing circuits.
Current – The flow of electric charge in a conductor, typically measured in amperes. – The current flowing through the circuit was measured to ensure it did not exceed the safety limits of the components.
Voltage – The electric potential difference between two points, which drives the flow of current in a circuit. – The voltage across the resistor was measured to verify Ohm’s Law in the laboratory experiment.
Waveform – A graphical representation of the variation of a signal with respect to time. – The oscilloscope displayed the waveform of the AC signal, allowing students to analyze its frequency and amplitude.
Modulation – The process of varying a carrier signal in order to transmit information. – Frequency modulation is commonly used in radio broadcasting to encode audio signals onto a carrier wave.
Electrons – Subatomic particles with a negative charge that flow through conductors to create electricity. – The movement of electrons in a conductor is the basis for understanding how electric current is generated and utilized.
Transformer – An electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. – The transformer was used to step down the high voltage from the power lines to a safer level for residential use.
Appliances – Devices or machines that use electricity to perform specific functions, typically in a household setting. – Engineers must consider energy efficiency when designing appliances to reduce electricity consumption and environmental impact.
