TDK s Environmental Technologies

Transcription

1 TDK s Environmental Technologies Ferrite An Amazing Magnetic Material Ferrite is a magnetic material that was invented in 1930 and was initially used in radios. Today, ferrite is once again in the limelight as a key environmental technology for the twenty-first century. Figure 1: The world s first ferrite toroidal coils (replicas) The photo to the left shows the world s first toroidal ferrite coils (replicas), which are exhibited in the TDK History Museum in Nikaho City, Akita Prefecture. They were created as prototypes for telephone loading coils. These coils were used in radios immediately after the start of mass production in 1937, and this was the world s first application of ferrite. Following the Second World War, the use of ferrite expanded greatly in devices such as radios and televisions. Ferrite was invented by Dr. Yogoro Kato and Dr.Takeshi Takei of the Tokyo Institute of Technology in TDK was established as a university-affiliated venture in 1935 to commercialize ferrite. Since then, TDK has developed a vast array of technologies centered on ferrite. Ferrite was crucial in the origins of TDK and even now plays an important role in its business. TDK and the Tokyo Institute of Technology were recently honored by the Institute of Electrical and Electronics Engineers (IEEE) with the grant of IEEE Milestones for the contributions of ferrite to society over many years. For more information, see Press Release under the Corporate Profile section of the TDK website. Following an 80-year history, ferrite is becoming an increasingly important material in electronic circuit devices that will be essential for addressing the global environmental problems that put the fate of humankind in question in the twenty-first century. It is truly amazing that even today, new development topics are being proposed and new products are being created in large numbers. This shows what an excellent material ferrite is. Ferrite is a type of sintered (baked) composite oxide ceramic consisting primarily of iron oxide and exhibits strong magnetic properties (a ferromagnetic material). Magnetic and dielectric materials are used in devices to create electronic circuits. Figure 2 is an electron microscope photograph showing the crystal grains and grain boundaries of ferrite. High-performance magnetic materials are created by controlling the size and the structure of the grains and their boundaries. Figure 2: The detailed structure of PC95, a high-performance soft ferrite material produced by TDK (1) Soft Ferrite and Hard Ferrite (2) Inductors (Coils) (3) Power Ferrite (4) Transformers (5) Ferrite Magnets (Hard Ferrite) (6) Conclusion

2 (1) Soft Ferrite and Hard Ferrite Ferromagnetic materials such as ferrite can be used to form inductors (see below) that store magnetic energy at high density. It is similar to a dielectric material storing electrical energy as a capacitor. One of the factors used to express the properties of a magnetic material is coercive force. Ferrite materials are broadly divided into those that do not have coercive force and those that have high coercive force. Ferrite with very little coercive force becomes a magnet that generates powerful magnetic force when wire is wound around a ferrite core that has been sintered in a cylindrical shape (this is called an inductor) and electrical current flows through the wires. The magnetic force, which is generated inside the core, is proportional to the resulting magnetic field. This is an electromagnet. When the current is cut off, the magnetic force disappears and everything returns to its prior state. If the direction of the electric current is alternated, the electromagnet has alternating north and south poles. This type of ferrite is referred to as soft ferrite. In contrast to this, when a powerful external magnetic field is applied to ferrite with high coercive force, a permanent magnet is created. Even when the magnetic field is removed, the ferrite maintains a strong magnetic force. Ferrite that can be made into permanent magnets in this way is called hard ferrite. Both soft and hard ferrite can store powerful magnetic energy internally and play key roles in a wide range of electronic circuits and electronic devices. There are many metallic ferromagnetic materials with strong magnetic force, but ferrite is a type of ceramic, which means it has high electrical resistance and maintains its excellent properties even when used with high-frequency signals. (2) Inductors (Coils) In the case of capacitors, the higher the permittivity (er) of the dielectric material used, the greater the capacitance. Similarly, ferrite has a value called magnetic permeability (µr), and materials with high magnetic permeability are strong magnetic materials. Ferrite is one such material. The higher the magnetic permeability, the greater the ability of an inductor to store magnetic energy (inductance). As mentioned in the previous section, inductors are generally made from a cylindrical soft ferrite core wound with copper wire and encased in resin or another material. This Figure 3: A ferrite core: Copper wire is shown in Figures 3 and 4. Inductors and capacitors are used in many different is wound around the internal circumference. types of electronic circuits and will continue to be used long into the future. Inductors are used in filters, noise elimination, power supplies, signal processing, and many other applications.

3 Two of the most important values indicating inductor performance are inductance and loss. These values are largely determined by the characteristics of the ferrite used in the core. When considering global environmental issues, using the smallest possible amount of resources (resource conservation) and not generating heat through unnecessary losses (energy conservation) are crucial. That is why the ferrite used in the cores of inductors that are essential for electronic circuits must be high performance (i.e., high µr for resource conservation) and low loss (for energy conservation). Figure 4: A cross-section of an inductor. After copper wire is wound around the ferrite core (Figure 3), the core is encased in resin for protection. Low loss is particularly important for components that handle high power such as power supply circuits. The VLS series of magnetically-shielded SMD power supply coils used in the power supply circuits of mobile phones and other mobile devices is introduced as an example (Figure 5). The VLS series includes some of TDK s most environment-friendly products, which it calls Eco Love products. (See the list of Eco Love Products for more information.) The products feature low loss and have been made smaller, lighter, and thinner to contribute to the miniaturization of mobile phones and other devices and to conserve resources. The strengths of high-performance ferrite materials are demonstrated perfectly. Figure 5: The VLS series of magneticallyshielded SMD power supply coils (3) Power Ferrite Below is a description of a ferrite core for high-efficiency reactors used in photovoltaic and wind power generation systems. This product is a Super Eco Love product for its outstanding environmental performance. A reactor is an essential component for storing and converting photovoltaic and wind power energy, important alternatives to fossil fuels. Direct current that is generated by photovoltaic or wind power energy and is stored is converted to 100 V alternating current for household use by a power conditioner. Reactors are used as inductor elements in the step-up circuits and inverter circuits that make up the power conditioner (Figures 6 and 7). The core material used in the reactor is PE90, a new low-loss power ferrite material recently developed by TDK. PE90 is a power ferrite that was developed by combining TDK s materials and process technologies based on its over 70 years of ferrite material development expertise to contribute to the creation of new and clean energy sources. Compared to core made of Sendust or silicon steel plates, materials that have been used in the past, the power losses occurring in the core are just one 2nd and one 16th, respectively, and power losses in the reactor element are 30% lower (Figure 8).

4 (For more information, see the latest Product Update File: PE90 Low-Loss, High Saturation Flux Density Ferrite for High-Power Reactors and Transformers.) Figure 6: Example of household solar power generation Figure 7: Block diagram of a power conditioner structure Figure 8: Ferrite core for reactor use and reactor (4) Transformers Transformers also play an important role in transforming electric power. Simply put, two wires are wound around a single ferrite core, and when a signal is input on one of the wires, the relationship between the voltage and current is transformed and power is output from the other wire. Figure 9 shows the operating principles of a transformer. As in the case of coils, the loss and permittivity of the ferrite material determine the energy saving and resource saving factors.

5 Figure 9: Transformer operating principles Note: No losses from the copper wire or ferrite are indicated here. In actual practice, these losses would have an effect. TDK developed high-performance (permittivity, loss, temperature characteristics, frequency characteristics, etc.) PC47 family of ferrite products for use in transformers and used its transformer design technologies accumulated over many years to optimize the structure, maximizing the characteristics of the material and producing significant energy-saving and resource-saving effects. Figure 10 shows a power supply transformer that contributes to energy and resource savings by digital consumer electronics such as liquid crystal televisions and plasma televisions. TDK expanded its product lineup from the EER series by launching the compact EGG series, which was announced in 2006, followed by the advanced ultra-compact ECO series of cores, which were recently released as Super Eco Love products (Figure 11). Figure 10: The ECO series of flyback power supply transformers

6 (5) Ferrite Magnets (Hard Ferrite) Figure 11: Transformations in power supply transformer ferrite core shape Note: Transformers use two of the cores indicated above. The FB12 series of ferrite magnets, the world s strongest, *1 is presented as Super Eco Love products with exceptional environmental performance. By developing new materials and process technologies, TDK is achieving substantial increases in magnetic force compared to earlier ferrite magnets. Magnets can be made much smaller and lighter, and this means that motors can be made smaller and lighter but maintained the same power (reduction in volume of approximately 23% *2 ). As a result, the weight of each automobile can be reduced by approximately 1.5 kg, contributing to improved fuel efficiency (approximately 0.1%). *3 *1. As of June 30, 2008, according to TDK investigations. *2. Compared to TDK s earlier FB6 series. *3. In the case of a compact domestic vehicle with 10 motors in use. Compared to TDK s earlier FB6 series.

7 (6) Conclusion In this way, ferrite holds tremendous new potential to contribute to addressing the increasingly serious global environmental problems that we face today. Increasing the performance and reducing the loss of ferrite materials leads to miniaturization and lower losses not only of ferrite cores, but also of the devices such as coils, reactors, and transformers that use ferrite. This in turn contributes to resource and energy savings by the equipment and sets in which those devices are incorporated. TDK is committed to making further technological innovations with the aim of protecting resources, saving energy, and contributing to the prevention of global warming.