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Latest EV Powertrain Designs in Electric Trucks and Buses

posted by Rugged Monitoring on 2020-07-21

Electric vehicle thermal management


Why do we need high performance electric buses and trucks?

In America, there are about 28 million trucks and buses which make up 10% of all vehicles on the road. Also, these trucks and buses contribute to 28% of all carbon emissions from the transportation sector. So, trucks and buses must turn electric as a recent study shows electrifying all trucks and buses would increase national electricity consumption by 13% but the total demand for energy would drop by 71% due to electric buses and trucks being substantially more economical than conventional gasoline vehicles. Also, the popularity of electric buses and trucks has increased in the last decade because of few remarkable EV technologies been incorporated into them. 


Latest Trends in Electric Vehicles – Electric Buses and Trucks

Fast charging technology in the E-mobility sector has seen some notable improvements. Currently, two-thirds of U.S. trucks travel 20,000 miles or less each year – an average of 80 miles per day if someone drives 5 days per week and 50 weeks per year. The mileage requirement for trucks is comfortably within the operating range of battery-electric vehicles with single charge every day. 

Some electric buses use capacitors to store their energy rather than batteries. The ultracapacitors can only store about 5 % of the energy than a lithium-ion battery can hold which limits the bus to a couple of miles per charge. But the capacitor charges much faster than the Li-ion Batteries. New solutions are being suggested for the areas where fast charging stations are not available, such as mobile charging solutions with 192 kWh (Kilowatt-Hour) of liquid cooler battery storage that can deliver DC fast charging of up to 80kw. 

Furthermore, the high-density battery of an EV means it holds more energy than most regular batteries which allows for a much more compact design. These batteries are gaining increasing acceptance in Electric Buses and Electric Truck due to the continuous decrease in battery prices. According to the United States Department of Energy, cost per kWh for EV batteries dropped from $500 in 2013 to $200 in 2019. Analysts are predicting further reduction in the price of a lithium-ion battery to app. $73 /kWh by 2030. 

Electric truck and electric buses have high performance traction motor that uses less power as compared to conventional IC engines to cover the same distance. For example, the electric truck uses only 10kwh per 5 miles whereas a diesel truck uses 33.7kwh per five miles. Electric buses and trucks give off zero emissions and they have a very quiet operation all while providing better acceleration and being easier to maintain when compared to traditional buses and trucks.

Lastly, the average range of an electric bus is roughly 180 miles whereas an electric truck's range varies from 300 miles to 550 miles with several well-established companies developing an EV with a 600-mile range. electric buses usually run 40,000 miles a year for 12 years which amounts to the battery lasting for 480,000 miles. Similarly, the speed at which new technology is being developed and implemented into these vehicles is enabling seamless transition from conventional gasoline buses and trucks to electric buses and trucks.

Electric Bus - ev battery testing

Challenges in Design and Testing of EV prototypes

The EV design and testing engineers of electric buses and trucks companies face a constant struggle in improving the performance of electric vehicles. There have been sustained efforts in developing new technologies and mechanisms to achieve higher performance. None of these new technologies have been successfully launched without performing extensive testing on EV powertrain. The safer and accurate powertrain testing at high voltages is the much needed by the instrument engineers of EV manufacturers. Thanks to fiber optic sensing technology that has made the testing safe, simple, and easy. With fiber optic temperature sensors, instrument engineers save time in setting up the test instruments and sensors. They do not have to worry about:

  • Putting additional isolation at High voltage components
  • Doing lengthy health and safety checks before every testing
  • Compensating sensors output for high electric and magnetic fields
  • Retesting multiple times to compensate for repeatability errors

How fiber optics sensors (FOS) revolutionizes electric vehicle testing?

The traditional sensors such as thermocouples are slow and inaccurate, as these sensors are vulnerable to electromagnetic noise especially when at high voltages. When EV testing happens at high voltages, there is a serious risk of short circuit or electrocution if traditional sensors are used. Therefore, E-Mobility requires a new and revolutionary technology for effective thermal management, as it defines the performance and longevity of any electric vehicle.

Fiber optic sensing technology has the following benefits over traditional sensors (thermocouples): 

  • The sensors are non-metal and perfectly safe to be used in High Voltage and high Magnetic test/operating conditions.
  • The sensors are small size (up to 0.4mm) that can fit at tiny spaces like Power Module, Battery Cells, Battery Module, Charging Pins etc. 
  • The sensors are isolation free and calibration free. Do not need any isolation or complex calibration.
  • High accuracy, as low as ±0.2⁰C with 100% repeatability
  • The sensors are based on the physical (optical) property of GaAs (Gallium Arsenide) crystal and remain stable (and accurate) over time (up to 100 years).
  • High Response time <40ms
  • Easy to route cabling & no power required for the sensor itself.

Rugged Monitoring Sensors and Monitors for EV Testing

Rugged Monitoring (RM) has developed different types of sensors and monitors for eMobility. The fiber optic temperature sensors are designed to meet accuracy and installation requirements of sensors inside the electric vehicles. The temperature signal conditioner (monitors) are customized to meet the operating condition of the EV, such as lower input power, higher vibrations, high operating temperature, and humidity etc. The high sampling CANBUS integration is implemented to mee the need of EV test rigs and their dataloggers. Many EV testing facilities are using fiber optic temperature sensors, LSENS-B, LSENS-T, LSENS-R, during the EV prototype testing. Their EV test rigs come with built in Fiber Optic temperature monitors , R501, O201 etc.