Replacing IGBTs with SiC saves energy, increases battery life and reduces the size and weight of the heat management system—which further increases EV range.
As the market demand for electric vehicles continues to increase – driven in part by government regulations on fuel efficiency and CO2 emissions, social awareness, and the overall trend toward greener transportation options – a growing number of automotive manufacturers are incorporating the latest power electronics technology in their designs to improve overall performance, increase efficiency, and reduce cost, weight, and complexity.
Electrification of vehicles is being driven by regulations and Indian authorities want electric vehicles to make up 70% of sales of commercial cars and trucks, 30% of private cars, 40% of buses and 80% of two- and three-wheelers by 2030. That would mean 102 million EVs plying the country’s roads, a dramatic increase from around 1 million in the 2022 fiscal year, according to estimates from researchers at the CEEW-Center for Energy Finance (CEEW-CEF).
The whole automotive industry is transforming, and commitments are being publicly announced by India’s leading automotive manufacturers. Tata Motors has reached an annualized rate of 55,000 to 60,000 and now the company is looking at an annualized rate of 1 lakh units by 2024. Mahindra & Mahindra has signalled to electrify a quarter of its SUV’s by 2027. The new entrant Ola electric announced its own EV by 2024 and targets a million cars by 2027. India’s largest carmaker Maruti also plans to launch its first EV by 2025. Other players like MG which has a success in the form of ZS EV and Hyundai with its Kona also plan to up their EV game.
Foreign companies have also been flocking to a market they see as ripe with potential. Japan’s Toyota Motor and South Korea’s Hyundai have announced $1.15 billion investments in the flourishing sector, while Japan’s Suzuki Motor has committed $1.26 billion to build a new factory for electric car batteries.
Kia Motors, and China’s MG Motors are also stepping up EV sales in India, and Germany’s Volkswagen aims to launch an electric model in the country next year.
At the heart of this monumental change are power semiconductors, which themselves are undergoing a sea change as the industry begins to orchestrate a shift from silicon to silicon carbide (SiC). The electric motor used to turn the wheels of an EV is typically powered by six silicon insulated-gate bipolar transistors (IGBTs) and diodes using a drive technique called pulse width modulation (PWM). This is where SiC can become advantageous due to its faster switching speeds and recovery characteristics. Replacing IGBTs with SiC saves energy, increases battery life and reduces the size and weight of the heat management system—which further increases EV range.
How SiC can accelerate the adoption of EVs
The new vehicles that are electric and have smart and connected features, are a significant contribution to automotive electronics and the vehicle performance. The ongoing semiconductor chip shortage has caused great concern to the automotive OEMs. The delay in new product launches or rising frustration of customers due to the longer wait are counter- productive. The traditional semiconductor chip technology has been dominated by Silicon for the last few decades. However, the new breed of vehicles (CASE – connected, autonomous, shared and electric) demand more from the automotive power electronics than what the silicon chips can meet. There is an exponentially rising interest in Silicon Carbide (SiC) that is expected to replace Silicon (Si) in many semiconductor chip applications in automotive. The use of Silicone Carbide (SiC) based devices promises a significant reduction in switching losses and permits far higher switching frequencies than what is possible today using pure Silicone (Si) devices.
What vehicle performance features will encourage users to switch from their traditional vehicles to electric vehicles (EVs), there are at least three themes that emerge strongly
The EV users want to get rid of their range anxiety – the automotive OEMs have to provide longer driving range per charge of their EVs.
The EV users want to charge their EV battery quickly – the OEMs have to provide fast and safe charging.
The EV users want vehicles to operate at high energy efficiency – the OEMs have to minimize the energy losses across the EV sub-systems.
The use of SiC-based chips in EVs promises to increase the efficiency and driving range, while reducing the weight and cost of the entire vehicle. Security of supply is also another factor for the successful adoption of SiC-based chip technology. The world’s first all – SiC powered traction system was installed in the Shinkansen Bullet Trains in Japan as early as 2015.
When there are many EV offerings in the market, the automotive OEMS will look at technology as the basis to create product differentiation. The traction inverter, together with the battery and electric motor, are the three key differentiation elements when comparing technology performance of EVs from different suppliers. Increased inverter efficiency results in lower energy losses on the way from the battery to the motor and enables a longer driving range. The inverter characteristics also have a direct impact on the vehicle performance and user driving experience.
When installing the power electronics, three factors are decisive: space, weight, and efficiency. Silicon carbide fulfils all the requirements because it has a higher efficiency and can be installed more compactly than conventional semiconductors such as silicon. SiC is a compound semiconductor and is a wide band gap (WBG) material and its properties are very different from the popular semiconductor material Si.
Silicon Carbide vs. Silicon in EV Power Electronics
SiC solutions are supporting various high voltage, high temperature components in the growing market for electric vehicles. Because an EV’s different systems are powered by different voltages, some Si devices also need to convert and portion out the correct voltages to window lifts, lighting, propulsion, and HVAC. Compared to Si devices, SiC technology supports these functions with greater speed, reliability, and efficiency.
Silicon carbide’s superior switching speeds are also supporting the development of faster chargers. Off-board chargers convert incoming AC into DC for battery storage. On-board battery chargers convert DC power from the battery into AC for the main drive motor. Silicon carbide performs these functions more quickly than silicon and with less heat and energy loss. Plus, silicon carbide components can be half the size (or smaller) than silicon devices. As SiC manufacturers continue to reduce defects in the material, the prices for SiC devices are expected to decline – an advantage for future EV applications.
SiC will meet the future demands for EV’s
Higher Voltage operation
When EVs are designed to operate at 400V, silicon is very competitive. By going to higher voltages – 800 to 1,000V, for example – faster charging is enabled with reduced weight and better packaging, thanks to much thinner wires, because higher voltage means fewer current amps at the same power level. 400V battery voltage is prevalent today, but there is a growing need for 800V battery systems. These systems are expected to become the standard as they achieve longer driving range per charge by enabling an increase in density and efficiency without incurring distribution losses or cable-size increase inside the car and on charging stations. SiC’s advantages over silicon technology are even more evident at the 1200V voltage rating required by the 800V bus. SiC can operate at higher switching frequency and potentially at higher temperatures limited by packaging.
The higher efficiency of SiC translates to more space inside a vehicle. It is very evident in the case of automotive onboard charging. To increase the range, designers increase the battery capacity. This means power levels for onboard charging need to increase, or it would not be possible to fully charge the battery overnight. In future, we may require bi-directional charging, like vehicle-to-grid (V2G). With silicon carbide, not only does efficiency increase, but higher switching frequencies can be realized. This results in smaller passives and reduced cooling effort.
Among the most challenging applications for SiC is certainly 5G mobile technology, capable of reaching speeds 20× higher than the previous 4G LTE technology. To operate faster, we need devices that are capable of handling higher power density, have better thermal efficiency, and are optimized for achieving high efficiency. These ambitious performance goals are a perfect match for the strengths offered by SiC devices, such as power MOSFETs and Schottky diodes, capable of operating at voltages of several hundred volts and at temperatures higher than silicon can tolerate.
India is gearing up for the future semiconductor chip technology
The Modi government approved sops worth Rs 76,000 crore rupees ($10 billion) spread over six years to boost local chip production, a move which is likely to help the South Asian nation reduce its reliance on expensive imports of the material used in everything from mobile phones to electric vehicles amid a global shortage. Currently, India relies on overseas manufacturers for almost all of its semiconductor requirement. The government is also looking at a complete overhaul of the sector, exploring ways to allow companies to merge, expand and operate without multiple bureaucratic approvals
The Indian government is now in active discussion with companies engaged in silicon semiconductor fabs, display fabs, compound semiconductors, silicon photonics, sensors fabs, semiconductor packaging and semiconductor design to set up shop in the country.
SiC holds great promise for a number of automotive applications, particularly for EVs. SiC can extend the driving range per charge compared with silicon, reduce the time it takes to charge a battery and contribute to the overall efficiency equation by providing the same range with lower battery capacity and less weight. SiC-based semiconductor chip technology is of strategic importance to any country aspiring for leadership in electric mobility. Since India does not have much infrastructure for Si-based chip fabrication and is planning to invest and create new infrastructure now, it would be good to leapfrog the technology curve and invest in SiC chip technology (especially for automotive applications). SiC chips, by enhancing the performance of EVs, can accelerate the adoption of sustainable mobility technologies in India.
By- Shilpa Shukla, Senior Editor, ELE Times