Definition
The increasing focus on electrification for a cleaner environment has fueled the need for electric power in different forms. Power electronics is the branch of electrical engineering that deals with the processing of high voltages and currents to deliver power that supports a variety of needs. From household electronics to equipment in space applications, these areas all need stable and reliable electric power with the desired specifications. Power supply in one form is processed using power semiconductor switches and control mechanisms to another form, supplying a regulated and controlled power. While switched-mode power supplies are a common application of power electronics where power density, reliability, and efficiency are of prime importance, motor control is gearing up with more electrification in transportation systems. Precise control and efficiency are key characteristics for power control applications. The study of power electronics is thus multidisciplinary, involving semiconductor physics, electrical motors, mechanical actuators, electromagnetic devices, control systems, and so on.
In power generation, especially in renewable energy, the generated power must be processed to meet the AC voltage specification of the power grid. For instance, a solar cell generates DC power whose output power varies with the operating voltage and incident solar irradiation. It is important to extract the maximum power available at the output of the cell and transfer it to the grid with the highest possible efficiency. So, the interface that connects the solar cell to the grid should provide AC power that matches the grid specifications and draws input power that operates the solar cell at its maximum power point. In addition to this, the conversion of this DC power to AC power should be with higher efficiency to minimize the losses in power generation. This is possible using power semiconductor devices with advanced control mechanisms that monitor the output and input parameters and control the switches.
Advancements in power semiconductor devices have paved the path for newer devices such as silicon carbide, gallium nitride field effect transistors (FETs), and power diodes. These devices have superior characteristics in terms of wide band gap that allows for high-voltage operation, thermal management, and efficiency. This has resulted in widespread usage of power electronics even in noise-sensitive areas, replacing the lossy linear power supplies and voltage regulators. The main advantage of these devices is that they can withstand high voltage when compared to the silicon devices. Thus, the systems can be designed with high-voltage capabilities, which, in turn, reduces the current and improves efficiency, for the same power to be delivered. In addition to this, operating the devices at higher switching frequencies helps in reducing the size of passive components, making the systems compact. The ability to handle higher temperatures simplifies thermal designs.
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The Importance of Power Electronics
The drive towards more electrification has resulted in the need for more electric power. Apart from power generation, power processing plays a key role in efficient utilization of the available power. It is important that the raw power is converted to a form that is usable in different applications. Power electronics plays a pivotal role in providing power based on the desired specifications. The basic application which shows the significance of power electronics in our day-to-day life is the fan regulator. Before the advent of solid-state fan regulators, bulky and lossy resistive fan regulators were used. To control the fan speed, the AC mains voltage is passed through a resistor that is connected in series with the fan. So, when the fan is on, there is constant power dissipation in the series resistor. Research has come up with more innovative ways of controlling the fans or motors, in general, by controlling voltage and frequency. This is possible with the availability of power semiconductor devices.
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In aerospace applications, especially in space applications, size, weight, and reliability are critical parameters. If power is handled at low frequencies, the transformers and other energy storage elements occupy a huge amount of space. With switching converters that work at high switching frequencies, the size of the energy storage elements is drastically reduced. The size of these components is inversely proportional to the switching frequency. So, devices with shorter switching times help to reduce the overall size and weight of systems.
State-of-the-art power electronic systems are capable of handling power from a few watts to several megawatts, enabling efficient and reliable interfaces between raw power and regulated power. As a result, hydraulic and mechanical actuators are being replaced with electric motors that can be controlled precisely using power electronic interfaces.
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The Benefits of Power Electronics
Electric power is scarce, and it is of prime importance to deliver the power to the loads with minimum losses. Advancements in power semiconductor research has resulted in more efficient chemistries such as silicon carbide and gallium nitride. The benefits of power electronics are:
- High power density power supplies
- Improved efficiency of up to 99% in power conversion
- Noise-sensitive applications such as in medical devices are also transitioning to switching power supplies because of the efficiency and reliability
- Power can be made available in the desired form and level as per specifications
- Increased clean power generation using power electronic interfaces to connect the sources to grid
- Wireless power transfer
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