Power semiconductors on guard of ecology

Published on April 09, 2019

Power semiconductors on guard of ecology



    In order to reduce CO2 emissions into the atmosphere, it is necessary to abandon the use of thermal power plants and switch to environmentally friendly energy. Such a transition cannot be made at once, first you need to increase the efficiency of use of electricity already generated, to reduce its losses during transportation to the consumer and conversion to various forms. A key element for solving these problems is power electronics and power semiconductor devices.

    Since solutions for energy are one of the most important segments of our business, we consider it important to talk about how our work helps to make the world cleaner. In particular, the power semiconductors that we manufacture can significantly save electricity and, as a result, abandon the construction of environmentally harmful power plants. Let's figure out how power semiconductors differ from ordinary ones and find out what their properties can save electricity and reduce CO2 emissions.

    Features of power semiconductor devices


    If you do not delve into the theory, then power semiconductor devices are the same diodes, transistors and thyristors, modified taking into account the scope of their application. Unlike microelectronic devices, power semiconductors are used at currents of tens, hundreds and thousands of amperes, voltages of hundreds of megavolts. Such loads require specific design solutions to eliminate breakdown of the pn junction.

    For example, the basis of a powerful power diode is a thin plate of a silicon single crystal in which a pn junction is formed. To prevent the plate from cracking due to heating, it is soldered with silver solder to thermocompensating disks of tungsten or molybdenum up to 3 mm thick. The resulting “sandwich” is placed in a sealed housing of a pin or tablet design.

    Pin diode design. Source

    The main element for converting electricity of high power - tens of megavolts and above - high-voltage thyristor . Structurally, it consists of four silicon layers with alternating conductivity, at the boundary of which three pn junctions are formed. Two extreme transitions are the anode and cathode, and the middle one is the control one.

    The thyristor has two stable states: “open” (current flows) and “closed” (no current). The state changes under the influence of voltage on the control electrode. Switching itself happens very quickly, although not instantly. In alternating voltage circuits, the thyristor will pass only one half-wave - the upper one. When the lower half-wave arrives, it is reset to the “closed” state. This property of the thyristor is used in switching power supplies to convert a sinusoid to pulses.

    On the basis of thyristors, heavy-duty converters are created in direct current power lines (power lines), direct current inserts between power systems, static reactive power compensators in alternating current power lines.

    The device of a high voltage thyristor. A source

    The main consumers of electricity operate with capacities below megawolts. The most common power element for this range is a bipolar field-effect transistor , Insulated Gate Bipolar Transistor, IGBT. IGBT is a power integrated circuit of many elementary cells. Each cell consists of a high voltage bipolar transistor with a field effect transistor included in the control circuit. Advantages of IGBT - small power consumption in the control circuit for switching on and off and high speed. MOS transistors

    are used to build low power converters., metal-oxide-semiconductor field effect transistor, MOSFET. These devices are also made in the form of a power integrated circuit containing hundreds of thousands of transistor cells. The operating voltage for MOS circuits, as a rule, is less than 500 V, the operating current is up to hundreds of amperes.

    Where and why are semiconductor devices used


    Industrial plants

    Due to their economy, controllability and high efficiency, power semiconductor devices increase the efficiency of electric power conversion. Soft starters, uninterruptible power supplies, electric motors and various electrical installations consume less and last longer due to the use of power electronic components.

    In devices containing an electric motor, more than half of the consumed electricity is spent on ensuring its rotation. An adjustable semiconductor frequency converter reduces electricity consumption by 30% without affecting other specifications.

    Electricity of the net

    The use of semiconductor converters in the transportation and distribution of electricity can save up to 25% of electricity. Thus, the widespread introduction of semiconductor power components allows you to abandon the construction of new power plants and dispense with the capacities of existing ones.

    Solar power plants The

    electricity received from solar panels must be converted for transmission to the electricity grid or for domestic use. The use of power semiconductor devices for controlling solar power plants increases their efficiency.

    Electric transport

    Electric cars use the energy stored in batteries. Thanks to the use of power electronics, energy conversion for the needs of various consumers in the car occurs with minimal losses. And the recovery technology allows you to put the braking energy into recharging the batteries and increase mileage.

    Moreover, it is interesting that the rapid development of electric transport forced manufacturers of semiconductor devices to look for new, more energy-efficient materials to create new power components. According to analytical studies, the semiconductor industry is massively converting its capacities to the use of silicon carbide and gallium nitride instead of ordinary silicon crystals.

    Power elements made of new materials are much more compact than traditional silicon ones, which suggests that the new generation power supplies will become 80-90% less. In addition, compounds using these materials have a 10 times higher specific power, operate at higher frequencies and in a wider temperature range, and the level of resistance in the open state and leakage currents are significantly lower than that of silicon counterparts.

    Prospects


    Many governments have adopted programs to reduce carbon dioxide emissions. For example, the Spanish government plans to reduce CO2 emissions by 20% by 2030, and by 90% from the 1990 level by 2050. The flagship role in reducing emissions is assigned to the electric power industry, and the transformation of other industries is planned to be carried out later.


    CO2 reduction plan by industry sector. Spain, 2019. Source

    It is estimated that by 2030 the capacity of the national electricity industry should reach 157 GW. Of these, 50 GW will be provided by wind power plants, and 37 GW - photovoltaic solar power plants, 27 GW - combined-cycle power.
    In addition, the package of laws stipulates that from 2040 in Spain it will be possible to buy only cars with zero emissions.

    Similar packages of laws have already been adopted or are being considered in the EU countries. This means that in the coming decades we can expect a rapid growth in sales of power semiconductor devices, since without them the implementation of the planned measures to improve the environmental situation is simply impossible.