Paper by Dr. Rainer Kallenbach, Executive Vice-President Sales Automotive Electronics" />

Mobility Solutions

Power electronics – a key to the electromobility of the future Paper by Dr. Rainer Kallenbach, Executive Vice-President Sales Automotive Electronics

  • at the 60th Automotive Press Briefing in Boxberg, June 2011
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  • June 09, 2011
  • Mobility Solutions
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press release

Ladies and gentlemen,

Electromobility requires completely new automotive electronics solutions: besides highly complex control functions, now switching functions for high operating voltages and amperages are also needed. For some 30 years now, improvements in automotive electronics have constantly been making modern vehicles safer, cleaner, more energy-efficient, and more comfortable. Right from the start, Bosch has played a significant part in these advances. Electronics are becoming an ever more important element of the car's value added. They give vehicles more “intelligence” and are steadily becoming more powerful, while at the same time smaller.

Highly integrated semiconductor chips and sensors are the key to this development. This is why Bosch itself has been manufacturing semiconductors and sensors for use in automotive electronics for many years. These technical advances are the prerequisite for further reductions in the price of automotive electronics despite improved performance – to make them affordable for everyone.

New challenges in automotive electronics
The electrification of the automobile poses new challenges for automotive electronics. Until now, developers have concentrated on making a car's control systems more and more intelligent. Now they are faced with the challenge of controlling high quantities of electrical power – up to hundreds of kilowatts – between energy sources and users. This kind of power is not only found in the electric motors of hybrid or all-electric vehicle powertrains.
Auxiliary units such as the vehicle's steering and cooling water pump are also being electrified and controlled electronically.

Power electronics are also a fundamental aspect of electrical industrial drives, electric railways, and inverters for solar energy plants and wind turbines. These kinds of power electronics grew out of industrial technology and are usually housed in large switching cabinets. This technology is not suited to automobiles, however. The required voltages, amperages, and power levels may be substantially lower. But the car environment poses particular challenges: space and weight requirements, robustness in the face of extreme mechanical and climatic conditions, and not least how to achieve volume production at a low cost. As a leading supplier of automotive technology, Bosch is particularly well versed in this field. That is why Bosch engineers have been working hard to come up with new technological solutions for automotive power electronics since 2005.

Example: energy management in hybrid vehicles
A considerable portion of the power electronics in a hybrid or all-electric vehicle is dedicated to the inverter. This component carries out the energy management for the powertrain. In hybrids, the inverter performs two functions. On the one hand, it controls the energy for electric driving, converting the direct current from the high-power traction battery into alternating current and thereby powering the electric motor that takes the place of the internal-combustion engine. On the other hand, the inverter also controls the important energy recuperation function, which saves on fuel. During braking, the electric motor becomes a generator, producing electricity and braking the car in the process.
Braking energy is converted into electrical energy. The inverter controls the current that recharges the battery. This stored energy can then be used later to drive the vehicle.

Power electronics thus play a central role in energy management. Bosch engineers are working hard to gradually optimize them: by reducing their space requirements, decreasing their weight, increasing their power, improving their efficiency, and lowering their cost. And they are making good progress. The first-generation inverter – which has been in series production for the Porsche Cayenne Hybrid and the Volkswagen Touareg Hybrid since 2010 – takes up around ten liters of space. The current, second generation of inverters, which will go into series production from 2012, is just as powerful but its electronics take up only around eight liters of space. And we are already working on the next generation for 2013, which will take up the same volume of space but feature a third more power.

Miniaturization – the key to electro-mobility
Our aim in consistently miniaturizing the power electronics is to make fuel-saving hybrid technology affordable for more and more drivers by reducing its costs. Bosch is carrying on the success story of automotive electronics in recent decades: more powerful, smaller, more cost-effective. The concerted development of the system, the control unit, and the semiconductor components in interdisciplinary Bosch teams plays an important role here. This is why, for instance, we have managed to construct an inverter that is particularly compact while at the same time optimizing its electrical and thermal characteristics through appropriate design.

Electrical energy is controlled within the inverter by integrated power modules produced using a special mold technology. Their “packaging” uses new assembly interconnect technology to combine several semiconductor components, such as power transistors and control circuits, in a very compact, robust, and at the same time efficient unit that is easy to install and cool. Compared to earlier solutions, developers have managed to attain significantly higher levels of current density, efficiency, and reliability.

To a great extent, Bosch develops and manufactures inverters and power modules itself – and also the integrated semiconductor components. It is only when development work on inverters, modules, and semiconductors is closely linked that these challenging requirements can be met.

In the power semiconductors field, Bosch agreed in 2009 to collaborate with the market leader Infineon, licensing a fundamental manufacturing process for these components. On this basis, Bosch can develop and manufacture the latest power semiconductors for its own specific applications in its own semiconductor fab. Bosch has recently invested 600 million euros in its semiconductor facility, adding a new wafer fab.

Ladies and gentlemen,

In the future, electric vehicles will make a significant contribution to energy-efficient individual mobility. This is why Bosch is dedicating a sizeable amount of its research and development expenditure to this topic – including new power electronics solutions.
But this research does not benefit the car alone; rather, it is increasingly being applied to the efficient supply of energy for our everyday lives – in keeping with our strategic imperative “Invented for life.”

RF00118 - June 09, 2011

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