My motto as a journalist is to report a story before it becomes a topic of conversation. So, I would like to wrap up this topic and move on to another.
However, after I was asked the same question by three people both inside and outside our company, I decided to write one more column about the Toyota Prius. They all asked, "Why don't Toyota increase the production of the Prius if it is selling so well."
I will explain the reason though it is not an established theory. It is a story of the supply of batteries and the unfortunate timing of generation change.
Both the Prius and the Honda Insight use a nickel-metal hydride (NiMH) secondary battery, but their next-generation models will certainly be mounted with a Li-ion secondary battery.
In the 28-page handout distributed at the announcement of the latest Prius, there are only five lines that explain about the battery. Probably, Toyota does not plan to revamp the NiMH battery any more.
Therefore, the company cannot build a big new plant to increase the production of the NiMH secondary battery because the era of NiMH battery will end before the investment is recouped.
The same thing will soon happen to silicon carbide (SiC). Currently, silicon (Si) is used as a semiconductor material for the inverter that rotates the motor. But Si inverters are likely to be replaced with SiC inverters in the near future because the loss of SiC inverters is half that of Si inverters. However, it is difficult to determine the timing of the replacement.
When will SiC inverters be commercialized? No matter how many times I asked this question, most manufacturers just said, "It will be in the 2010s." It has a range of 10 years. Well, I understand it. It has been very difficult to make predictions on SiC technologies. And many manufacturers have already failed to do so. If their predictions had been correct, SiC inverters would have been commercialized long ago.
Also, the full-scale dissemination of electric vehicles is expected to begin in the 2010s. Some estimates include increases in the number of gasoline hybrid vehicles to 9.62 million units by 2018 and to 12 million by 2020. But there are some unstable factors such as oil price and developmental status of batteries. So, if asked when SiC inverters will be commercialized, they have to say that it will be in the 2010s.
However, that cannot be an answer. What we want to know is, "When in the 2010s?" Automakers want to use SiC inverters when electric vehicles start to be disseminated in earnest. If the timing gets off, it will be a problem.
If the development of SiC inverters is delayed, makers have to use Si inverters for the meantime. Automotive inverters are larger than those for home appliances and information appliances. The output of the motors for hybrid vehicles is 10 to 165kW. So, the number of inverters used in them is 10 to 100 times more than that used in air conditioners.
Even so, no manufacturer will make a large investment in production facilities for Si power semiconductors only for vehicles. They know that SiC inverters will make those facilities useless. As a result, SiC inverters might be delayed while Si inverters are in short supply and high priced, the worst scenario for automakers. There are many challenges to overcome before the era of hybrid and electric vehicles comes.
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