Technical analysis of the urban elf Roewe E50 pure electric vehicle

On the evening of November 5, 2012, SAIC's first mass-produced pure electric car, the Roewe E50, was officially released at the Shanghai World Expo Convention Center. The Roewe E50 is a pure electric car based on a new vehicle platform and developed with the core technologies of "three electrics" independently mastered. What are the technical highlights of this urban boutique pure electric car? SAIC's technical experts gave us a relevant introduction. Let's read it out below.

● Fashionable and smart design

Dolphin-style hatchback body design

The exterior design of the Roewe E50 is derived from the E1 concept car, but many sci-fi and advanced elements are simplified. It adopts a dolphin-style short-beak hatchback body design, which looks fuller. The tailgate adopts a dolphin-back integrated design, and the overall appearance has rounded lines, which conforms to the principles of aerodynamics and helps to reduce the wind resistance coefficient of the whole vehicle.

The headlights adopt a single-cavity design, with popular LEDs embedded underneath, which contrast with the LED taillights at the rear of the car, making the entire vehicle more dynamic.

As it is a pure electric car, the front of the car does not have the traditional car air intake grille, but in the middle is a shield-shaped plug cover (fast charging socket), with a blue E in the middle, making it easier to identify its electric identity. Another household power socket is located on the left rear hand side, which is the traditional refueling position.

Simple interior design

The E50 uses a three-spoke multimedia integrated control steering wheel with silver sports trims at the bottom, which makes it look dynamic. The instrument panel uses a multi-function digital instrument with 3D effect, which exudes a fashionable aesthetic. The intelligent integrated human-machine exchange system is located in the middle of the central control, and the display screen is a 6.5-inch touch screen, which looks full of technology.

As a two-door car, the E50 adopts a 2+2 interior space layout. The front and rear seats are both black and white, blending in with the center console.

As an A00-class small car, the wheelbase of the Roewe E50 is 2305mm. Since the entire vehicle is a new design based on electric vehicles and has been reasonably optimized, the interior space is quite ample.

The E50 also uses the popular one-button start function, but the difference is that the one-button start button is integrated on the key, and you only need to insert the key to start. It is worth mentioning that the Roewe E50 is also equipped with a humanized SMART HOLD electronic handbrake system, which has functions such as automatic shutdown, automatic parking after the key is pulled out, and hill start assist, which helps to improve driving safety.

● Exclusive vehicle platform for pure electric vehicles

The newly launched Roewe E50 is a completely newly developed vehicle platform designed for pure electric vehicles, which is different from most domestic pure electric vehicles that are modified from internal combustion engine platforms. Since it was developed around the pure electric vehicle platform at the beginning of the design, it can avoid a series of problems that occur in "modified pure electric vehicles", such as the battery pack occupying the trunk space, the uneven weight distribution of the front and rear axles of the vehicle caused by the installation of batteries, etc.

The E50's drive system (electric motor, integrated electronic box) is placed at the front of the car, the power battery pack is placed slightly behind the bottom of the car body, and the 12V battery is placed at the bottom of the trunk. The front suspension is a McPherson independent suspension, and the rear suspension is an H-type torsion beam semi-independent suspension.

It is reported that since the component layout of the pure electric vehicle was taken into consideration at the beginning of the design of Roewe E50, reasonable optimization was used to ensure the safety of the whole vehicle while improving the vehicle's handling and space utilization. You can go and experience it in depth in a future test drive.

● “Three-Electricity” core technologies

Motors, electronic controls, and batteries ("three electrics") have always been the technical bottleneck in the development of electric vehicles. Let's take a look at the features of the "three electrics" core technologies on the Roewe E50, a small electric car.

Lithium iron phosphate battery

In fact, as a pure electric vehicle driven by electricity, the battery is the source of all power. Its performance directly affects the effective use of the electric vehicle. The Roewe E50 uses lithium iron phosphate batteries. What are the advantages of this battery over traditional batteries? You should know that traditional batteries have memory. If they are often used in the condition of being fully charged but not fully discharged, the capacity will be lower than the rated capacity.

This type of lithium iron phosphate battery has no memory characteristics, has higher charge and discharge efficiency, and is more suitable for electric vehicles that require frequent charging. In addition, the weight of lithium iron phosphate batteries of the same specification and capacity is lighter than that of traditional lead-acid batteries.

According to the relevant technical person in charge, the lithium iron phosphate battery of the Roewe E50 has a very stable power level, with a self-discharge rate of no more than 5% in three months. At minus 20 degrees, the battery capacity decay is less than 10%, and after 2,000 charge and discharge cycles, the battery loss is still less than 20%, and the actual service life is more than 10 years. In addition, the battery module has a temperature control system that can effectively prevent the battery from overheating. The effective range of the Roewe E50 at a constant speed of 60 kilometers is 180 kilometers.

Permanent magnet synchronous motor + integrated electronic box drive system

In addition to batteries, the electric drive system is also an important component of pure electric vehicles. The maximum power of the Roewe E50 is 52kW, the peak torque reaches 155Nm, the acceleration from 0 to 50 kilometers is 5.3s, and the maximum speed reaches 130 kilometers per hour, which is enough power for a pure electric car running in the city.

The electric motor uses a permanent magnet synchronous motor developed entirely by Roewe, which is waterproof and dustproof and has high stability. It is matched with an integrated power electronics box, which integrates the inverter and high and low voltage DC converters in one piece, reducing the size and weight of the electronics box to a certain extent, which is beneficial to the chassis layout of this small car.

VCU Intelligent Vehicle Control System

The VCU intelligent vehicle controller jointly developed by SAIC Motor and BOSCH has more than 20 ECU control units and integrates the internationally advanced CAN-BUS system, which can effectively improve the transmission speed between external controllers, thereby ensuring the stability and security of the system.

The CAN-BUS management system mainly includes the power system and chassis management bus, the OBD2 digital diagnosis management bus, the multimedia management bus and the body management bus.

● Vehicle safety protection system

Whether it is a traditional internal combustion engine vehicle or a pure electric vehicle, its safety performance is also what we are most concerned about. For electric vehicles, whether the battery system can be well protected in a collision is also very important.

Lightweight body structure

As a small car, its safety performance is also of great concern to us. Especially for a small car with a very compact body structure, since there is not much space to buffer the impact force, the material used in the body design is more important. On the other hand, the body cannot be too heavy, otherwise it will affect its handling and energy saving.

The body of the Roewe E50 is made of lightweight materials and ultra-high-strength steel structure. The driver's cabin is made of ultra-high-strength steel structure, the front buffer beam is made of aluminum alloy, and the tailgate is made of SMC composite lightweight material. The charging port, small door, and PEB crossbeam are also replaced by new synthetic materials.

It is reported that the power battery compartment located at the bottom of the vehicle body is also equipped with an anti-collision structure, and ultra-high-strength steel is used as a support at its key stress points to ensure the safety of the battery in extreme collisions.

The body is made of high-strength materials and has been effectively optimized to achieve good buffering and energy absorption when impacted, thereby protecting the safety of drivers and passengers. Since the E50 is designed based on a pure electric vehicle platform, the balance between ergonomics and vehicle safety is taken into consideration in the design of the motor, battery and body. The Roewe E50 is designed in accordance with the C-NCAP four-star collision safety standard and has undergone rigorous collision tests in accordance with strict American standards. The results are all safe, qualified and in line with design requirements.

Battery protection system

The power battery can be said to be the "heart" of a pure electric vehicle. It is very important to protect the "heart", especially during wading or collision. Due to the characteristics of the power battery, it is easy to cause leakage or fire.

At present, most of the power batteries of pure electric vehicles are placed at the bottom of the vehicle body, and the environment is also very harsh. For example, driving in rainy days and on dusty roads are severe tests for the battery. According to technical experts, the waterproof and dustproof capabilities of the power battery of Roewe E50 have reached the high standard of IP67.

Waterproof and dustproof level is one of the most stringent automotive test standards at present. For example, after 6 hours in an environment full of extremely fine dust particles, no dust intrusion was found in a battery that meets the IP67 standard; the battery was immersed in water at a depth of 1 meter for half an hour, and the seal did not fail. In addition, since the power battery works in a high-voltage environment, the insulation design of the vehicle body and the collision power-off protection are also particularly important.

● Brake energy feedback system

Energy recovery, an energy-saving and environmentally friendly technology, is a major feature of electric vehicles. The pure electric car Roewe E50 also uses this technology. How does the E50's brake energy recovery system work? The principle is also very simple. When the car is decelerating, the inertia of the vehicle drives the motor to reverse, and then charges the power battery, reducing the energy loss during braking, which is also helpful to increase the cruising range.

In fact, this method is somewhat similar to the traditional use of engine traction for braking, but here the motor replaces the engine. This can improve the braking efficiency of the car and reduce the braking distance while charging the battery. On the other hand, it can also reduce the wear of the brake pads.

Summary: Unlike some other pure electric vehicles transformed from traditional cars, the Roewe E50 is a small car redesigned based on electric vehicles. The body layout has undergone a series of reasonable optimizations, making this car small but fully equipped. It integrates SAIC Group's "three-electric" core technologies of power battery system, electric drive system, and electric control system, making this small car have good performance. How this pure electric car positioned for urban travel will perform in the future still needs to be tested by the market.