Low-speed electric vehicles (LSEVs) are ideal for covering short distances in urban areas. In addition, stricter environmental protection requirements in more and more cities, for example in the form of restricted traffic zones, are likely to give these vehicles a considerable boost. For example, P&S Intelligence predicts that the global LSEV market will grow from $35.2 billion in 2017 $68 billion by 2025. Countries with large populations and many densely populated areas, such as China and India, will account for the largest share. Accordingly, the production of low-speed electric vehicles, for example in China, is also increasing: Research In China forecasts an increase of 15 million vehicles between 2021 and 2025.
Diversity of micromobility
Low-speed electric vehicles, which are also included under “micromobility”, include a wide variety of vehicles. They can be used as commercial vehicles or for passenger transport in urban areas. Since they are below the passenger car class, the requirements regarding type approval differ significantly from those for traditional passenger cars.
One type of LSEV, for example, is a two-wheeled vehicle. These include e-scooters, e-bikes, and pedelecs, including two-, three-, and four-wheeled cargo bikes. The latter are particularly popular with service providers, such as couriers and delivery services, as well as families, as they allow fast movement in densely populated city centers and offer a certain amount of storage space.
Three-wheeled vehicles include motorcycles with sidecars for private use and small passenger cars, such as the Piaggio Ape. They are suitable for passenger transport, for example in the tourism sector, and are also used by postal services.
Four-wheeled models range from e-quads to small e-cars, such as the Renault Twizy, and small e-vans. Depending on their actual size and design, they are used for a variety of commercial and personal transportation applications.
Performance, speed, and range of small LSEVs
Depending on their vehicle class, low-speed electric vehicles can achieve a range of speeds and power ratings. Micromobiles and low-speed two-wheeled vehicles can reach top speeds of 25 km/h. They typically have a rated power of 1 kW. The larger two and three-wheeled types generally have a maximum power rating of 4 kW and travel at up to 45 km/h. Low-speed four-wheeled vehicles also travel at this maximum speed; their rated power, however, can be as high as 6 kW. Heavy four-wheeled models, on the other hand, can reach top speeds of 90 km/h with a rated power of 15 kW. The range of low-speed electric vehicles varies depending on their power output; many can travel around 150 km on a single battery charge.
Reference designs for applications in low-speed electric vehicles
For these reasons, Rutronik's Automotive Business Unit (ABU) also sees great potential in low-speed electric vehicles. Following the successful reference design for a bidirectional HV switch for 800 V DC and 50 A, Rutronik is now working closely with Vishay to develop sample applications for low-speed electric vehicles with a 48V electrical system. These are the on-board charger (OBC) for the 48V battery system and the traction inverter. The designs focus on converter efficiency, compact design with low installation height, and automotive-grade quality. Integrated in a show car, it was first unveiled at electronica India in September 2023.
Advantages of LSEVs
For developers/suppliers
- Less stringent safety regulations
- Lower cost of motor and electronic components compared to 400V and 800V vehicles
- Higher reliability of components compared to 400V and 800V vehicles
- No high voltage risks
For users
- Easy charging at standard sockets
- Convenient for short trips in urban areas
- Require little parking space
- Climate-friendly driving
- Permitted in some environmental protection zones
The on-board charger
The OBC provides a maximum charging power of 3.6 kW. Its key components are the new VS-ENM040M60P power modules, optimized power factor correction (PFC) coils, and a pulse transformer developed specifically for this application. A power module integrates a semi-controlled input rectifier, a diode and a MOSFET for power factor correction, and a half-bridge for the pulse transformer. The package used is Vishay’s EMIPAK-1B. It enables higher power densities than a structure with discrete semiconductors and its press-fit contacts ensure fast assembly with secure connections to a PCB.
The passive components also play an important role, as their properties are a key factor in determining the efficiency of the circuitry. An integrated LLC transformer, such as the MTBB133971 from Vishay Custom Magnetics, is used as the pulse transformer. The resonant inductors are already incorporated.
The traction inverter
The traction inverter has a rated power of 15 kW with a short-term peak power of 25 kW. Vishay’s N-channel automotive trenchFETs in the PowerPAK 8x8L Reverse package are used as power semiconductors. The top-side cooled package allows them to be thermally coupled directly to a heat sink rather than being cooled by the PCB. This reduces thermal resistance and improves heat dissipation.
Summary
The new reference designs for low-speed electric vehicles provide hardware developers with design templates that can significantly reduce the time-to-market of their own circuit designs. By using the latest high-performance components, the circuitry achieves high power density at low cost.
For more information and a direct ordering option, please visit our e-commerce platform at www.rutronik24.com.
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