Bosch Debuts New CV-Specific Electric Motor and Inverter
The 230 e-motor can be paired with Bosch’s advanced SiC inverter to cut down on energy losses and increase driving range.
A new Bosch electric motor paired with an advanced power inverter bring an integrated propulsion solution to the commercial vehicle (CV) market. “Electrification is the future, and we think there’s going to be a wide variety of e-powertrains for the medium-duty segment in the very short term,” said Dr. Shyam Jade with Bosch in North America.
Jade, a senior engineer of control system development for electrified vehicle system engineering, spoke with SAE Media during September’s Motor Bella event in Pontiac, Michigan. “This new e-motor is an enabler, whether it’s for a full electric, a hybrid or a fuel-cell commercial vehicle,” Jade said. The motor’s debut coincides with the company’s 40% investment increase, year-over-year, in e-mobility.
The 230 motor gets its name from its stator diameter – 230 mm (9.05-in.). “The e-motor is slightly bigger than what you see in a typical passenger electric vehicle. But it’s significantly smaller than a typical gasoline or diesel engine,” Jade said, noting the e-motor’s compact size and other attributes will appeal to the CV market.
Battery-electric CVs are a rarity in 2021, with less than 1% of the medium-duty and heavy-duty vehicles (Classes 4-8) claiming the designation, according to Kenny Vieth, president and senior analyst for ACT Research, a firm that provides data, industry analysis, and forecasting services for CV and transportation markets. By 2026, battery-electric adoption is expected to reach 11%. “But there are material differences in adoption between medium-duty Classes 4-7 and heavy-duty Class 8. In the former, we anticipate sales rising to around 20 percent in 2026 with Class 8 at just 4 percent adoption,” Vieth predicted.
Scalable to Class 8
In the Bosch 230, oil cooling and water cooling have specific roles. The rotor and stator are internally oil cooled, and the active parts are installed in a water-cooling jacket. “Oil cooling really helps with the heat transfer,” Jade said.
Scalability makes the 230 e-motor appropriate for a range of CV applications. “We can size it for light-duty commercial vehicles, medium-duty trucks, all the way up to Class 8 semi-trucks. The 230 e-motor stays the same, but we would make modifications to scale it,” Jade said. “For really large vehicles, it might take two of the units.”
Bosch’s 230 can provide up to 230 kW (300 hp) of continuous power, an important asset in medium-duty vehicles that are on the road for a long period of time, Jade said. Common usage, such as towing a payload up a hill, also requires reliable e-motor power. Hairpin winding technology helps achieve high copper fill in the stator. “With that winding technology, we’re able to reduce significantly the package size, and we’re able to make the e-motor more power dense,” he said.
Efficiency is a hallmark of the 230 motor with an 800-volt rating. “We get up to 97 percent efficiency with this system in terms of converting the electrons into rotational energy,” Jade said. That efficiency is significantly higher than a typical gasoline or diesel engine’s 30-40% brake-thermal efficiency.
Efficient SiC inverter
The 230 motor can be paired with Bosch’s advanced inverter with silicon carbide (SiC). This semiconductor material improves electrical conductivity. SiC helps reduce heat losses, enables higher switching frequencies and improves the power density versus a traditional inverter with silicon. “Our inverter with SiC helps drive inverter efficiencies above 99 percent and the overall system efficiencies above 97 percent,” Jade said. The SiC inverter is a Bosch-first for the CV market.
E-motor and inverter efficiencies help increase a vehicle’s driving range. “That’s always a concern for our end customers. You really want to cut down on the energy losses, and we feel we’re doing our part with this solution,” Jade said.