The Basic Classification of Electric Motor

Nowadays about 70% of all electricity in industry is used for providing electromotive force by driving electric motor. The beginning of development in electric motor is originated from discovery of Electromagnetic Induction by Michael Faraday.

Fig 1. Classification of Motor

Motor is largely categorized by 2 parts : AC motor and DC motor. In fact, between these two types, there is also Brushless DC motor(BLDCM). It cannot be considered as a typical motor but we will figure it out later, not now. DC motor is divided into 2 types : Separatly Excited and Self Excited. It depends on how it makes Excitation power in order to generate magnetic flux in field coil of a stator.
AC motor is also divided into 2 types : Synchronous motor and Induction motor. It is not presented in diagram but Synchronous motor can be divided by 3 types : Permanent magnet, Wound Field and Reluctance. And in Permanent magnet. we use semiconductor, which is so important. So we will figure it out too, later.

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NPC Inverter and Psim Simulation

1. 3-Level NPC Type Inverter Fig 1. 3-Level NPC Type Inverter Fig 2, Switching Fig 1 is 3-Level NPC Type Inverter and Fig 2 indicates how it works. Fig 2 indicates how each switch is activated. There are 3 switching states which are called P, O, N. In each state, the output voltage becomes +V_dc/2, 0, -V_dc/2. Fig 3. Switching Mode Left in Fig 3 indicates circuits when positive voltage and the right one is for negative voltage. Let's check how it works! Considering P switching state in positive voltage, S1 and S2 are on, and S3 and S4 are off. So we can ignore the circuit below. As a result, the output voltage is +V_dc/2. In the same way, you can see how the rest works. 2. Control Fig 4, SPWM In Fig 4, we can see how SPWM works. The offset voltage is applied to control the circuit. The common value for offset voltage is 0. It makes the reference polarity voltage and the reference phase voltage same. 3. Circuit Fig 5. Circuit for Psim ...

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Harmonics

What is harmonics? When we think about harmonics, we can easily come up with harmony in music, which means the composition of individual sounds. What about electrical power? In an electrical power system, a harmonic is a voltage or current at multiple of the fundamental frequency of the system. Then, What is the fundamental frequency? Before we discuss harmonics, we should know what the fundamental frequency is. Maybe you know the relationship between voltage, current, and resistor, for example, V=IR. Assume that there is a system where a DC voltage supply and a resistor are connected in serial. Then, if the voltage is AC, the current is AC. And It's totally because of the resistor in this system. That is, the resistor is linear. So in this system, we have one voltage sine wave and one current sine wave. And they can be called a fundamental frequency wave. Fig.1 What if the resistor is replaced with other components which is non-linear? The current will ...

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What is Energy Storage System (ESS) and its role in Grid?

Energy Storage System (ESS) Methods of generating electricity by renewable energy such as wind power and solar power, rather than the methods by conventional power plants are becoming important both politically and technically not only in Korea but also around the world. In the case of Korea, the importance of renewable energy is emphasized as the country pushes for the "2050 carbon neutrality" policy. However, there are certainly drawbacks to renewable energy. Wind power and solar power are the representative sources of renewable energy. Wind power generators are affected by wind speed, and photovoltaic generators by solar radiation. Because of this inherent nature of renewable energy, the amount of power output from renewable energy is highly volatile. Many studies to reduce this volatility are going on , and in this post, we will first learn about ESS and how it is typically utilized to decrease bad natures of renewable energy and eventually to help stabilize ...

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Grid Tech

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