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Posted on 02 July 2019

Genesis – Let there be Chips!

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IGBT module for use in photovoltaic systems in private homes

The best-selling book in the world, the Bible, starts with the ‘Book of Genesis’, “because it is about the creation of the World …”, explains the ecumenical Bible translation – and the word for ‘creation’ is ‘genesis’ in both Greek and Latin.

By Klaus Schlund, Director Technical Marketing, EBV Elektronik

 

The Genesis chip is an IGBT module, co-developed with and produced by Vishay for use in photovoltaic systems in private homes. This IGBT module is used as the power unit in the inverters for converting the DC voltage generated by the solar cells into AC voltage that can be fed into the grid. The big players in the inverter industry use patented technologies in the power unit, but there is also a market with numerous not so large inverter manufacturers, who do not use patented topologies. It was precisely these companies, who rely on standard topologies, which constantly struggled in the past to keep up with the big companies because it was extremely difficult for them to meet the requirements of the market in terms of efficiency and also to achieve a very high level of reliability at the same time.

Econopack 2

The first EBVchip Genesis now enables these companies to compete much better with the competition, with only minimal changes to the software being required in order to integrate Genesis into an existing solution. Since, in developing Genesis, EBV Elektronik had a solution with high efficiency and utmost reliability in its sights from the outset, Genesis employs a standard boost topology with a bridge configuration. For the casing, EBV and Vishay consciously opted for a wellproven technology in the form of the ECONO2 (Econopack 2). Although cheaper casings than ECONO2 are available, which are also used in some of the latest generation of inverters, there is another important element that has to be factored into the equation, namely that the Econo2 casing permits an exceptionally high level of reliability. Since end customers base their calculations of the amortisation period for their photovoltaic systems on a functional period of over ten, often over 15 years, and sometimes even over 20 years, it is unacceptable for them to have to exchange the inverter after only five or six years.

Genesis: Its creation

The basic idea of Genesis involves offering the inverter developers a solution that is extremely easy to use, which they can integrate into their existing design within the scope of a migration path and without major effort, and that works with a high level of efficiency and reliability, whilst offering good electromagnetic compatibility. It is precisely these requirements that Genesis satisfies, with the effect that the over 50 prospective customers in Europe, who could use this RoHScompliant module, have already expressed serious interest in Genesis: from Spain to Turkey and from Italy to Germany through to Eastern Europe. EBV Elektronik defined the design initially with one key account customer, whereas the subsequent fine tuning ensued in close collaboration with several customers and developers from Vishay.

EBV developed Genesis for designs in which six-pack modules are already used. Many of these customers already had ideas as to what they require, but, owing to the high NRE costs of a customer-specific design, they have not implemented these ideas thus far. It is precisely here that the performance of the EBVchips comes into play, which Slobodan Puljarevic, President and CEO of EBV Elektronik phrased very aptly when presenting the concept of EBVchips back in early 2010: “With EBVchips, we are now the extended arm of many thousands of customers to the manufacturer.” Accordingly, Genesis is definitely not designed for one customer only and not just for one national market, but can be used the world over. Without the orientation to vertical markets, the EBVchips also would not have even been possible.

Genesis Power Module

In January 2010, EBV presented the EBVchips concept and, even before electronica 2010, various customers had already received working Genesis products. EBV will begin shipping Genesis in quantities to customers as early as Q1 2011.

When, after the initial talks with customers, EBV began to look for a suitable manufacturer for Genesis, the company first spoke with various partners who, within the scope of the EBV line card, constituted potential manufacturers, before finally opting in favour of Vishay.

With regard to the technical feasibility, EBV could in theory have also implemented the Genesis project with other partners from its line card, but Vishay showed an exceptionally high degree of flexibility and, from the very outset, expressed its readiness to lend the project its full support and to implement it as quickly as possible. In other cases, the decision for a specific manufacturer can also depend solely on the technology.

The current variant of Genesis is already the third version of the specification. The individual iterations were necessary because new customer requests have constantly been incorporated into the design. Without these additional iteration steps, EBV could have launched the module even faster onto the market. Since the experts at EBV spoke directly with the engineers in the factory without all the usual bureaucratic rigmarole, it was possible to streamline this iterative fine tuning process.

EBV supplied the first samples without a built-in thermistor as a means of thermal protection, since most customers did not want this functionality. Nevertheless, EBV is capable of developing variants also with a built-in thermistor within the space of two months. Since the responsible engineers at the Vishay and EBV factories communicate with each other via a direct communication channel, it is possible to make changes to the design in real-time.

Genesis: The data

Genesis is a complete power unit integrated into one module for single- phase inverters in photovoltaic applications. With its ratings of 600 V / 50 A (in continuous operation) for a conversion frequency of 4 to 30 kHz, Genesis is targeted precisely at applications in the residential sector, which mostly have a power rating of between 2.5 and 6 kVA. Even in the choice of semiconductor devices integrated into the module, EBV had, from the very outset, an extremely high-quality end product in mind. Thus for instance, the trench IGBTs, with their low collector to emitter saturation voltage of just 1.65 V, constitute the best compromise between conduction and switching losses, whilst the silicon carbide diodes ensure particularly low switching losses and, at the same time, exceptionally good EMC performance, since the blocking interval recovery time of SiC diodes is zero, such that the additional snubbing required can be significantly less than with conventional solutions.

The FRED silicon diodes act in turn as a boost bypass in the case of high input voltages, such that the module is provided with an effective means of protection also against reverse polarity of the solar panels. As such, Genesis is ideally equipped for use in boost stages, which implement the concept of ‘maximum power point tracking’ of the photovoltaic modules with a downstream single-phase bridge for DC/AC conversion.

Genesis-circuit-configuration

The new module thus constitutes, as it were, an upgrade of existing solutions. It is an additional item in the product range, which is not available in this form from other manufacturers. Although comparable modules do exist with silicon carbide in the boost stage, there is no equivalent module prior to the market launch of Genesis that also contains a SiC diode in the bridge circuits.

The FRED silicon diodes act in turn as a boost bypass in the case of high input voltages, such that the module is provided with an effective means of protection also against reverse polarity of the solar panels. As such, Genesis is ideally equipped for use in boost stages, which implement the concept of ‘maximum power point tracking’ of the photovoltaic modules with a downstream single-phase bridge for DC/AC conversion.

The new module thus constitutes, as it were, an upgrade of existing solutions. It is an additional item in the product range, which is not available in this form from other manufacturers. Although comparable modules do exist with silicon carbide in the boost stage, there is no equivalent module prior to the market launch of Genesis that also contains a SiC diode in the bridge circuits.

What is more, the modules that come closest to Genesis are not housed in Econo2 casing, although these other casings can sometimes even be cheaper. In terms of all its electrical properties, the Econo2 casing is however better than the module casings otherwise used. What is more, many customers who are now looking to use Genesis have thus far devised their solution discretely. Also from a thermal aspect, having a base plate from solid copper makes Econo2 casing better than the solutions used to date. The low thermal resistance between the chip and the casing improves the thermal performance, which is then further enhanced by being installed directly on the heat sink. Furthermore, the installation of a module is much easier than the installation of individual components, which boosts the reliability, whilst the system production costs decrease at the same time due to less time being required for the production.

Genesis from EBV is certainly not the cheapest, but is probably the most cost-effective solution on the market. Although the belief prevailed in the industry to date that a solution such as Genesis would be too expensive, because, however, EBV customers finally achieve their objectives with this admittedly expensive solution, they are also prepared to bear the additional costs on account of the significantly more expensive silicon carbide diodes.

Compared with the overall cost of the complete inverter, the costs of the IGBT module are however not so high, meaning that a more efficient and reliable solution in a better casing represents the cheaper option at the end of the day. Due to the interplay of the increased efficiency, higher reliability and lower system production costs, the total cost of ownership (i.e. the total development costs) of the Genesis modules is less expensive than with other possibly comparable solutions. If a manufacturer has to exchange an inverter on account of a fault during the warranty period, this decisively reduces the profitability of this company. With Genesis, the manufacturers get the higher efficiency as an additional sweetener so to speak. Consequently, this is not a low-cost migration solution, but a migration towards higher performance coupled with higher efficiency.

Genesis is just the beginning

The great thing about EBVchips is the fact that each chip is different, which is why the experts at EBV need to constantly think anew as to which approach and which semiconductor manufacturer they should use to implement a project. At the same time, however, EBV is acquiring more and more of a routine in defining specifications. In the beginning, it took a lot of convincing, but comments from semiconductor manufacturers have since been mounting up under the motto “this project could also have been implemented very well with us as partners”. Because the manufacturers can see that EBV is truly highly committed and can produce initial products even after such a short time, other manufacturers are also getting actively involved such that, depending on the potential product, a certain competitive situation can most definitely arise between the semiconductor manufacturers for a corresponding project in the field of EBVchips.

A module such as Genesis can of course be implemented faster than pure semiconductor designs, which normally take up to two years from the idea to the finished chip. Depending on the project, EBVchips are EBV-exclusive for 3 to 5 years and sometimes even longer. Genesis, for example, will only be available from EBV.

Genesis is ‘just’ the beginning. In early 2010, EBV commenced active discussions with customers and also acquired a great deal of additional knowledge at the same time. Thus, it is not only in the Bible where Genesis comes at the start of an extremely long-lasting development and story that constantly produces new highlights; whereby in the case of EBVchips, it is perhaps better to say “will produce”.

 

 

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