The automotive industry is transitioning from internal combustion engines using fossil fuel to electric-power-driven systems. Power storage, energy recovery and voltage control technologies are critical to moving these trends forward, and electric power devices that efficiently convert energy to the required power are in demand. Switching power supplies have recently become the mainstream from the viewpoint of conversion efficiency and component downsizing. There is also a shift from conventional energy systems, wherein power is conducted in one-way systems from the power generation source or storage battery to the electronic device, to two-way systems that recover the excess energy generated by power-consuming devices. To this end, power devices and power coils are needed to show complex transforming and rectifying functions, to be capable of handling greater power levels, and also to be smaller in size.
In terms of performance, inductors should have low loss and operate with high efficiency at high frequencies. Until recently, the majority of choke coils used were coil components with copper wire wound around magnetic cores made of ferrite. When a current is applied to the copper wire, magnetic fluxes are produced in the core. The number of magnetic fluxes has an upper limit depending on the material and the core size. Therefore, original functions cannot be performed if a current that produces magnetic fluxes exceeding this limit is applied. The result is a loss in power and consequently heat generation. Since the saturation flux density of ferrite is not very high, the DC bias characteristics decline due to magnetic saturation when the choke coil is reduced in size.
As metal materials have a higher saturation magnetic flux density than ferrite, many magnetic fluxes can be produced. Therefore, in comparing the two using the same size cores, metal is able to deliver the required performance even when a larger current is applied. However, as the current flows out as it is with metal, an eddy current is created when an alternate voltage is applied, causing a large loss. This loss not only shortens the battery life, but at the same time converts into a large volume of heat.
Nowadays automotive design requirements are becoming more and more demanding: ECUs design have to fulfil more functionality in small size or package. In the meantime high power, high current, high efficiency, low power consumption are required. To meet these challenging design requirements Panasonic has developed with its ETQP Series a perfect answer.
Panasonic Power Choke Coils (PCC) – A new generation of choke coils
Given the design trends for downsizing/miniaturization, it appears clear that demand will grow rapidly for a new generation of choke coils that can deliver excellent performance characteristics in a smaller footprint. But how can you find a way to solve the problem as mentioned before and build the high performance yet compact inductors e.g automotive applications need? To meet the demands of high performance and yet downsizing, engineers at Panasonic developed for their Power Choke Coil Series (ETQP-Series) a metal composite powder magnetics choke coil technology that is based on an original Metal Array powder material.
The ETQP-Series provides following key advantages:
- Controlling the particle size of the metal powder material leads to high magnetic flux, high permeability and therefore to better DC or AC bias.
- Thermal aging is prevented and high temperatures up to 150°C can be withstood.
- Due to its monolithic structure and by reducing the magnetic flow pass way, better electrical characteristics than ferrite can be fulfilled. Thereby a reduction in case size between 30-50% can be archived.
Panasonic paid especially attention to design-questions for its ETQP-Series as it is able to withstand continuous vibrations of up to 30G of stress. This was archived by damping terminal structure and leading the inductance wire outside and tightly to the body of the coil. Thereby high solder joint reliability and thermal cycle were archived – for a temperature range between -40° til +150°C and this several thousand cycles.
FIGURE 1
The graphs shown in Figure 2 illustrate the significant performance advantage of the new PCC/ ETQP-Series over a comparable ferrite by comparing inductance values over bias current as well as inductance over temperature. With the ferrite device inductance drops drastically once DC bias has reached a certain point. Leveraging the advantages of its new metal magnetic powder, the ETQP exhibits far more stable performance when being exposed to high current along with high temperature stability. Clearly the ETQP device tends to have none saturation and stable inductance value allowing it to support higher levels of current.
FIGURE 2
Moreover, the new ETQP-Series demonstrates low power loss at high frequencies than competitive wire wound ferrite products and secures thereby high efficiency.
FIGURE 3
ECU’s have become more complex, advancing from 8 to 64 bit processors and controlling everything from fuel injection to emissions, from real time engine diagnostics to throttle control. Along with these increases in capability has come the need for components with large current and high frequency capabilities. Panasonic’s Metal Composite (MC) Choke Coils are perfect for such applications. Thanks to their high heat resistance, the ability to withstand high vibration, compact size and low audible noise Panasonic’s Metal Composite Power Choke Coils are suitable for many automotive applications.
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Please also compare: Farnell