In recent years, with the emergence of new car-making forces such as Tesla in the field of electric vehicles, the light of traditional car companies seems to have been covered up for the most part. But in fact, most of the first-line traditional car companies have deep technical accumulation in the field of pure electric, and BMW is naturally among them. BMW's exploration of pure electric vehicles began decades ago, and it has been nearly a decade since the last cross-era i3 and i8 products were launched. During this decade, BMW has not stopped moving forward, and their latest research and development is the iX3 that is now active in the market. As the crystallization of BMW's new era of pure electric technology, what are the unique features of the iX3 in electrical and electronic technology? Let's explain it in detail.
The BMW iX3 began mass production in Shenyang, China, in 2020 and sold back worldwide, followed by a mid-term overhaul in the second half of 2021, a comprehensive overhaul of the exterior interior. These visible changes are not the focus of this article, and we will focus on the three-electric system of the new car. Most people who know the BMW iX3 know two numbers, 500km, 6.8s, the former is the range of the new car, and the latter is the 0-100km/h acceleration time of the new car. Behind these two figures, a large number of new electrical and electronic technologies are being supported.
The BMW iX3 is based on the CLAR platform, which was designed with compatibility with all kinds of power in mind. Taking X3 as an example, it supports four different power types of pure fuel, light mix, plug-in hybrid and pure electricity, so there is actually no such thing as "oil to electricity". One of the most intuitive proofs is that the ground clearance of the iX3 and the occupant/trunk space in the car are not reduced compared to the fuel version of the X3, which is the obvious advantage of the compatible platform over the "oil to electricity".
The fifth-generation eDrive system is the BMW iX3 that has been mentioned countless times in the publicity, and the iX3 is also the first model to be equipped with this system. The characteristics of the fifth generation of eDrive drive systems can be summarized in two main points: integrated and sustainable. Let's first look at the integration part.
A complete picture of the fifth-generation eDrive drive system (Figure 1)
Fifth generation eDrive electronic drive system disassembly diagram (Figure 2)
Figure 1 in the figure above is the whole picture of the fifth generation eDrive electric drive system, which adopts a highly integrated design, integrating the three components of the motor (Figure 2 left), the actuator (in Figure 2), and the inverter (figure 2 right) in an electric drive module. One of the advantages of this is to reduce the quality - the power density of the new generation of eDrive system is increased by about 30% compared with the previous generation; the second advantage is to reduce the volume - the eDrive electric drive assembly placed on the rear axle does not occupy the rear seat and luggage compartment space; the third advantage is high efficiency - the motor output shaft, the actuator input/output shaft and the drive shaft are adjacent to the parallel design, the transmission distance is short, the loss is small, and the transmission efficiency is naturally significantly improved.
The motor stator uses a flat wire winding to reduce resistance and improve efficiency
The second feature of the fifth-generation eDrive drive system is sustainability. At present, the mainstream vehicle motors on the market have two kinds of AC induction asynchronous and DC permanent magnet synchronization, of which the former has the advantage of large power, but the disadvantage is low efficiency and difficult speed regulation; the latter has high efficiency and fast speed regulation response, but it is easy to cause permanent magnet demagnetization phenomenon under high load (so it limits the power), and the permanent magnet (NdFeB) needs to use rare earth materials, which is not conducive to sustainable production. The fifth generation of eDrive system creatively adopts the AC synchronous motor (excitation synchronous motor) without rare earth design, uses direct current to make the rotor generate a fixed electromagnetic field, and rotates synchronously with the three-phase rotating magnetic field generated by the stator through alternating current, taking into account the advantages of high power, high efficiency and fast speed regulation, and the production process does not use rare earths to ensure the sustainability of the environment.
The new AC synchronous motor has a maximum power of 210 kW, a peak torque of 400 N·m, a maximum power of 134 kW for energy recovery, a maximum speed of 17000 rpm, and a comprehensive efficiency of 93%. This motor is the hero behind the BMW iX3 0-100km/h acceleration time of 6.8 seconds and the extreme speed of 180km/h (electronic speed limit). From the table on the left of the above figure, it is not difficult to see that the motor enters the constant power range (always maintains the peak torque of 400N·m) when the vehicle speed is 0-60km/h (corresponding to the motor speed 0-4500rpm), and the speed of 60km/h (corresponding to the motor speed is 4500-15000rpm) enters the constant power range (always maintains the maximum power of 210kW), and has excellent performance in the full speed range.
If the acceleration results are behind the blessing of electric drive technology, then the mileage behind the battery technology to "support". The battery pack of BMW's new iX3 is also part of the fifth generation eDrive system, which uses square cells, the entire battery pack contains 10 modules composed of 188 cells, with a total weight of 518 kg, providing a capacity of 80 kWh, with a usable capacity of 74 kWh, making the iX3 have a cruising range of 500 km. The battery pack is a classic "sandwich" construction with a liquid cooling/heat (PTC + heat pump) design to maintain battery performance reliability at extreme temperatures.
Like electric drive systems, one of the cores of the fifth-generation eDrive battery system is sustainability. Its ternary lithium battery cell adopts NCM811 cathode material, that is, the ratio of nickel, cobalt and manganese is 8:1:1, which reduces the amount of rare metal cobalt under the premise of ensuring energy density for sustainable development. In fact, the energy density of the new generation battery pack equipped with NCM811 battery cells is 20% higher than that of the previous generation. At the same time, thanks to the slim design, it can be placed between the front and rear axles of the iX3 without affecting the interior space and ground clearance, and the center of gravity of the iX3 is 7.4cm lower than that of the fuel version of the X3, and with the 47:53 front and rear counterweights, it can bring more control skills required by BMW.
In terms of safety that electric vehicle users are most concerned about, the battery pack of iX3 has achieved due protection from the cell level to the housing, such as a layer of insulating film and isolation pad between the battery cell and the battery cell, and then sprayed with insulation materials, and there are 3 layers of space protection between adjacent cells. The shell of the entire battery pack uses high-strength aluminum alloy and adds a collapsed energy absorption structure, which can also ensure that the battery cell is not affected by external forces as much as possible in the event of a collision. Finally, the battery pack of the BMW iX3 was rigorously tested by BMW when it was developed, and it meets the highest standards in terms of electrical safety.
In terms of charging, the BMW iX3 supports ac slow charge and DC fast charge. Among them, AC slow charging uses the charging wall box provided by BMW to support a charging power of up to 11kW, which can be fully charged from zero in 7.5 hours. If the DC fast charging is used, the BMW official DC fast charging pile can support a charging power of up to 150kW. As can be seen from the table on the right side of the figure above, the first 20% of the charging power can reach the highest 150kW charging power, and then slowly decline, and the charging power of about 100kW can still be maintained when charging to 60%, and the final time can be charged from 0% to 80% in 34 minutes.
Summary of the full text
The fifth-generation eDrive system on the BMW iX3 has an integrated, sustainable and high-efficiency electric drive module, high energy density, low rare earth consumption, safe and reliable battery pack and high-speed charging capabilities to help the iX3 perform powerfully and reliably. I believe that after reading this analysis, you will find that the BMW iX3 triple electric system is undoubtedly one of the most advanced on the market today, which also reflects BMW's deep accumulation in electrical and electronic technology. BMW in the field of pure electric is not a hit, a blockbuster, BMW iX3 is worthy of a technical milestone.