An Article by Motohiko Hamada, Nikkei Automotive Technology
"I was beginning to become concerned while rushing around to cover SiC (silicon carbide) stories. Will it be ready in time for the era of electric vehicles if things continue like this?
SiC is a semiconductor used for an inverter that rotates the motors of electric and hybrid vehicles. Silicon (Si) is currently used for this purpose but will be replaced by SiC in the near future. However, the shift to SiC could end up in failure if if timing is wrong.
The energy loss with SiC is only half that with Si. Also, the heat generated by SiC is half that of Si, making it easier to release the heat and allowing its use in a high temperature. Si inverters are operable at 200°C, while SiC inverters can be operated at 300°C. And Rohm Co Ltd confirmed that its SiC inverter operated at 400°C, making heat release even easier.
Heat release becomes more effective with smaller heat generation, higher temperature, larger heat dissipation area and better thermal conductivity. If the heat generation is small enough and the temperature is high enough, the surface area and the thermal conductivity can be reduced. The reduction in thermal conductivity means, for example, replacing a water-cooled system with an air-cooled system.
The "Lexus LS600h," a hybrid vehicle manufactured by Toyota Motor Corp, has a cooling system that forcefully "water-cools electronics devices that should not get wet" in its inverter. We should not forget the fact that materials with a high thermal conductivity are high in electrical conductivity (low insulation properties) in many cases.
Toyota's technology is fantastic, but there is something wrong with it. If an air cooling system can be used, we will not have to resort to an unreasonable method like this.
When will SiC be commercialized, exactly?
Mitsubishi Electric Corp went further than other companies and expressed its plans to commercialize SiC converters. The company said, "We aim to commercialize it in fiscal 2010," when it made an announcement about its measures against global warming in November 2008. But other companies carefully interpret this announcement, saying "Mitsubishi has users in its group" and "the production volume is unclear."
Manufacturers other than Mitsubishi only said, "it will be in the 2010s," although I asked them several times. But I understand their attitudes because the progress in SiC technology is difficult to forecast and a number of manufacturers have already failed to predict it. If their previous predictions had been accurate, SiC inverters would have already been realized.
Also, the full-fledged electrification of automobiles is anticipated for the 2010s. For example, JP Morgan Securities Inc predicts that the market scale of gasoline hybrid vehicles will reach 9.62 million in 2018, twenty times the current number.
However, this prediction is subject to change, depending on crude oil prices and the progress in batteries. They can only say, "it will be in the 2010s," when asked, "When will the full-scale electrification start?"
This is not the answer we want. The point is "when in the 2010s?" Manufacturers want to use SiC inverters when they produce electric vehicles in full swing. Therefore, the gap between the timings of SiC inverter commercialization and the full-fledged manufacturing of electric vehicles could be a problem.
If the development of SiC inverters falls behind, manufacturers will have to use Si inverters. Automotive inverters are much larger than those for home electronics and home information appliances. Hybrid and electric vehicles will require a capacity of 15 to 40kw and 40 to 100kW, respectively, which are 10 to 100 times that of an air conditioner.
If electric vehicles start to dominate the market, huge volumes of semiconductors will be required. It is believed that the demands for semiconductors will remain low for the time being and the operating rates of semiconductor production facilities will drop. But the excess capacity will not be sufficient to meet the demands arising from the full-swing production of electric vehicles.
Nevertheless, manufacturers will not make substantial investments in the Si production equipment. This is because they know that Si production equipment will end up as excess facilities, being soon replaced by SiC. This situation could result in a delay in SiC development and a shortage and high price of Si, placing automobile manufacturers in a very serious situation.
We have a long way to go before seeing the era of electric vehicles."
Source: Tech-On
"I was beginning to become concerned while rushing around to cover SiC (silicon carbide) stories. Will it be ready in time for the era of electric vehicles if things continue like this?
SiC is a semiconductor used for an inverter that rotates the motors of electric and hybrid vehicles. Silicon (Si) is currently used for this purpose but will be replaced by SiC in the near future. However, the shift to SiC could end up in failure if if timing is wrong.
The energy loss with SiC is only half that with Si. Also, the heat generated by SiC is half that of Si, making it easier to release the heat and allowing its use in a high temperature. Si inverters are operable at 200°C, while SiC inverters can be operated at 300°C. And Rohm Co Ltd confirmed that its SiC inverter operated at 400°C, making heat release even easier.
Heat release becomes more effective with smaller heat generation, higher temperature, larger heat dissipation area and better thermal conductivity. If the heat generation is small enough and the temperature is high enough, the surface area and the thermal conductivity can be reduced. The reduction in thermal conductivity means, for example, replacing a water-cooled system with an air-cooled system.
The "Lexus LS600h," a hybrid vehicle manufactured by Toyota Motor Corp, has a cooling system that forcefully "water-cools electronics devices that should not get wet" in its inverter. We should not forget the fact that materials with a high thermal conductivity are high in electrical conductivity (low insulation properties) in many cases.
Toyota's technology is fantastic, but there is something wrong with it. If an air cooling system can be used, we will not have to resort to an unreasonable method like this.
When will SiC be commercialized, exactly?
Mitsubishi Electric Corp went further than other companies and expressed its plans to commercialize SiC converters. The company said, "We aim to commercialize it in fiscal 2010," when it made an announcement about its measures against global warming in November 2008. But other companies carefully interpret this announcement, saying "Mitsubishi has users in its group" and "the production volume is unclear."
Manufacturers other than Mitsubishi only said, "it will be in the 2010s," although I asked them several times. But I understand their attitudes because the progress in SiC technology is difficult to forecast and a number of manufacturers have already failed to predict it. If their previous predictions had been accurate, SiC inverters would have already been realized.
Also, the full-fledged electrification of automobiles is anticipated for the 2010s. For example, JP Morgan Securities Inc predicts that the market scale of gasoline hybrid vehicles will reach 9.62 million in 2018, twenty times the current number.
However, this prediction is subject to change, depending on crude oil prices and the progress in batteries. They can only say, "it will be in the 2010s," when asked, "When will the full-scale electrification start?"
This is not the answer we want. The point is "when in the 2010s?" Manufacturers want to use SiC inverters when they produce electric vehicles in full swing. Therefore, the gap between the timings of SiC inverter commercialization and the full-fledged manufacturing of electric vehicles could be a problem.
If the development of SiC inverters falls behind, manufacturers will have to use Si inverters. Automotive inverters are much larger than those for home electronics and home information appliances. Hybrid and electric vehicles will require a capacity of 15 to 40kw and 40 to 100kW, respectively, which are 10 to 100 times that of an air conditioner.
If electric vehicles start to dominate the market, huge volumes of semiconductors will be required. It is believed that the demands for semiconductors will remain low for the time being and the operating rates of semiconductor production facilities will drop. But the excess capacity will not be sufficient to meet the demands arising from the full-swing production of electric vehicles.
Nevertheless, manufacturers will not make substantial investments in the Si production equipment. This is because they know that Si production equipment will end up as excess facilities, being soon replaced by SiC. This situation could result in a delay in SiC development and a shortage and high price of Si, placing automobile manufacturers in a very serious situation.
We have a long way to go before seeing the era of electric vehicles."
Source: Tech-On
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