800 V electric drive system
1. Introduction
During the promotion of new energy vehicles, they are faced with the problems of short driving range, difficult charging, and slow charging. The charging efficiency is improved by increasing the current and system voltage. High current will cause high heat loss of components. Therefore, by increasing the system voltage Become the mainstream choice for improving efficiency. As the core component of new energy vehicles, the electric drive system is the key to reflect the performance and core competitiveness of automotive products. At present, domestic and foreign brands such as Volkswagen, BMW, Mercedes-Benz, BYD, Geely, Great Wall, etc. have layouts in high-voltage platforms , the 800 V electric drive system based on the high-voltage platform has also become a key technology that the industry focuses on research.
This paper mainly summarizes the development trend and technical difficulties of the 800 V electric drive system from the aspects of industry research background, user development driving force, and key core technologies, and gives a high partial discharge inception voltage (Partial Discharge Inception Voltage, PDIV), the insulation scheme of corona-resistant electromagnetic wire, and summarize the technical scheme of electromagnetic interference and suppression of bearing current corrosion, aiming to improve the industry's awareness of 800 V high-voltage electric drive platform technology.
2.Development trend of 800 V high voltage electric drive technology
On September 4, 2019, Porsche released its first pure electric sports car - the new Tayca. Among them, the first batch of models released are the new Taycan Turbo S and the new Taycan Turbo, both of which are "Porsche E-Performance" (Porsche E-Performance), representing the highest performance of the Porsche pure electric production vehicle Taycan series . At present, the common electric vehicle system voltage is 400 V, and the new Porsche Taycan is the first mass-produced model with a system voltage of 800 V. This model adopts a dual-motor four-wheel drive configuration (Table 1). It is equipped with the 800 V technology derived from the Le Mans championship racing car 919 Hybrid, coupled with dual permanent magnet synchronous motors and a two-speed transmission on the rear axle, taking into account both performance and driving range. demand. The 800 V three-electric system has low power consumption and a built-in booster to increase continuous output power, increase charging power, shorten charging time, and reduce system quality. Both front and rear drive dual motors use AC permanent magnet synchronous motors and HairPin hairpin winding technology , the slot fill rate is as high as 70%, and laser welding is used locally. Porsche announced that the Taycan can support more than 10 consecutive ejection starts without torque output derating, and its motor thermal performance design capability is better.
Table 1 Technical indicators of Porsche Taycan electric drive system
Note: The technical indicators are organized according to the era of EDT electric drive and the advanced technology of automobiles. This electric drive has 2 types of inverters, and the torque and power in the expanded number are 600 A peak output.
On December 2, 2020, Hyundai Motor Group world premiered a new modular platform for electric vehicles, E-GMP (Electric-Global Modular Platform, E-GMP). The platform adopts 800 V voltage electrical architecture, bidirectional charging, charging power can reach 350 kW, 80% can be charged within 18 minutes, and 100 km can be traveled after 5 minutes of charging. Hyundai Motor said that its Integrated Charge Control Unit (ICCU) is the world's first patent to increase 400 V to 800 V through a motor and inverter, and realize stable charging of 800 V batteries with 400 V fast charging piles technology. In 2021, ZF, BYD, Geely, BAIC, Changan, GAC, Dongfeng, Xiaopeng, etc. will follow up and release the 800V high-voltage platform architecture, and the models are expected to start mass production in 2022. The 800 V high-voltage electric drive system is about to usher in explosive growth.
3. Demand Analysis of 800 V High Voltage Electric Drive System
According to the survey data of Autohome, the top 10 reasons (TOP10) for consumers not to buy new energy vehicles are shown in Figure 1 [1]. Consumers pay the most attention to the guarantee of driving range and charging convenience. Driving range and charging are the two major pain points in the application of electric vehicles.
Figure 1 Summary of problems in the use of new energy vehicles [1]
The "Pure Electric Vehicle Consumer Survey Report" [1] released by the Innovation Center for Energy and Transportation (iCET) shows that more than 50% of consumers hope that the driving range will be as high as possible, and 38.9% of consumers think that under actual driving conditions A driving range of 400-500 km can meet daily needs, and it is not necessary to blindly pursue a high driving range. For BEVs, the typical power loading value is about 100 kW·h, as shown in Figure 2.
Figure 2 Data survey on driving range expected by consumers[1]
With the popularization of electric vehicles, users' acceptance and recognition of electric vehicles has gradually increased, and the requirements for electric vehicles have also gradually increased. The main appeal of users is fast and convenient charging. Like traditional car refueling, they can quickly find charging equipment and complete fast charging within 15 minutes.
Under the high-voltage electrical architecture platform, under the premise of constant power, the driving range will increase and the charging speed will increase. The electric drive system will also be easier to achieve high power and high torque output, and the operating efficiency will be higher. Under the boundary of the main demands of current consumers, the most suitable voltage level is 800 V, as shown in Figure 3.
Figure 3 The advantages of high-voltage electrical architecture and the selection of its voltage platform
4. Key technologies of 800V electric drive system
The nominal power supply voltage level of conventional automotive electric drive systems is 400 V. After increasing from 400 V to 800 V, the following technical problems will be faced:
(1) The peak value of overvoltage is high when the 800 V high-voltage electric drive system is working, and conventional electronic components, mechanical parts, basic insulating materials and their structural processes cannot adapt to the significantly increased electrical stress hazard;
(2) It is difficult to balance the output power, economy, and electromagnetic compatibility of the 800 V high-voltage electric drive system. How to achieve multi-dimensional, multi-disciplinary, and multi-field overall collaborative optimization through technological innovation;
(3) The vast majority of car companies in the industry still use 400 V high-voltage platforms. In the short term, charging interfaces and charging piles in many areas of my country will not be replaced quickly. How can 800 V electric drive systems be compatible with the existing mainstream 400 V medium-voltage platforms? Charging infrastructure is one of the important issues that need to be resolved in the development of the new energy vehicle industry.
It is necessary to focus on the high-reliability, high-performance, high-adaptability, and high-safety technology directions for the 800 V high-voltage system automotive electric drive scenario, and conduct in-depth research on the selection of high-voltage power electronic components, the development of new insulating materials and processes, and the electrical corrosion of high-speed bearings. Suppression, application of automotive SiC power devices, Boost regulator development, high-frequency electromagnetic interference suppression, integration of drive and charging, zero-torque control of boost charging, capacitive charge pump booster and other core technologies (Fig. 4).
Figure 4 800V high-voltage electric drive system key technology research and development path
4.1 Selection of high withstand voltage power electronic components
After the nominal bus voltage of the electric drive system is increased from 400 V to 800 V, the internal control unit circuit of the motor controller remains basically unchanged, while the various components of the power conversion unit circuit and its printed circuit board (Printed Circuit Board, PCB) ) will be designed completely differently. See Table 2 for the main component selection design changes.
Table 2 Voltage withstand upgrade of power electronic components when switching from 400 V to 800 V system[2]
4.2 New insulating materials and processes
A motor driven by an inverter is called a variable frequency motor. The variable frequency AC motor completes the modulation of the output voltage amplitude and frequency through the inverter, and the inverter completes it in the form of Pulse Width Modulation (PWM). During PWM modulation driving, the inverter output waveforms are square waves with different pulse widths, and the voltage is modulated to make the current passing through the motor windings approximate to a sinusoidal current. PWM modulation drive generally uses Insulated Gate Bipolar Transistor (IGBT) or Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) power devices, switching time ≤ 50 ns , the rise time of the square wave of the PWM output voltage is very short (0.2-0.4 μs), and the voltage change rate can reach 10 kV/μs. When it is applied to the motor winding, it will produce an uneven inter-turn voltage distribution, and at the same time, it will generate at the end of the motor. The phenomenon of refraction and reflection of the voltage traveling wave, the peak reflected voltage is superimposed on the high-voltage square wave pulse, which further leads to the occurrence of overvoltage shock at the motor end. There are peaks in the motor terminal voltage waveform, and the peak value can reach 1.5 to 2 times the bus voltage. The high electric field caused by the high voltage will increase the number of partial discharges (Partial Discharge, PD), and eventually lead to breakdown.
Compared with the traditional power frequency sinusoidal power supply AC motor, the motor insulation problem faced by the variable frequency motor working under the high frequency steep rising edge square wave voltage is more complicated and harsh. On the one hand, the high-voltage square wave pulse exerts a higher amplitude voltage impact on the stator winding insulation; on the other hand, the pulse frequency is as high as 10 kHz, and the high-frequency effect aggravates the aging effects of dielectric loss, partial discharge, and space charge on the insulation. Turn-to-turn insulation is the weakest link in the insulation system of variable frequency motors. After using the inverter variable frequency drive, the inter-turn voltage of the winding can reach more than 10 times that of the power frequency AC power drive [3-5].
Under the high-frequency high-voltage square wave pulse voltage, the research on the aging model of insulating material life prediction is not yet mature. Guastavino[6] carried out life model tests on twisted wires, and established a voltage-frequency-heat multi-factor joint aging life model, see formula (1).
In the formula, L(V,T,f) is the life of the insulating material; V is the voltage; f is the frequency; n is a function of temperature T; C, m are coefficients related to materials and test conditions [6].
It can be seen from formula (1)
that the insulation life is inversely proportional to the applied PWM voltage pulse amplitude, PWM carrier frequency, and ambient temperature.
The influence of PWM waveform parameters on the characteristic parameters of partial discharge can be summarized in Table 3.
Table 3 The influence of PWM waveform parameters on the characteristic parameters of partial discharge[7-9]
The process of insulation aging failure under high-voltage and high-frequency square wave pulses can be analyzed in two cases with and without partial discharge. The insulation aging mechanism is shown in Figure 5.
Figure 5 Mechanism of rapid insulation failure under high-voltage and high-frequency pulse voltage[7]
In the 800 V electric drive system, in order to resist the inevitable high-frequency PWM pulse damage to the insulation, it is necessary to carry out key technical research in the aspects of insulation material technology, structure design, filter design, system integration, etc.
4.2.1 Improvement of insulating materials
It is necessary to look for new partial discharge resistant materials. Currently, there are two technical routes: high PDIV magnet wire and corona resistant magnet wire. The comparison of the two advanced electromagnetic wire technology routes currently mainstream in the industry is shown in Table 4.
Table 4 Two technical routes of partial discharge resistant electromagnetic wire [10-11]
4.2.2 Improvement of insulation structure and process
The improvement of the insulation structure mainly improves the reliability of the insulation by increasing the PDIV level of the insulation system, the corona resistance level, and avoiding mechanical damage (wear, impurities, bubbles, bending, etc.). The difficulty lies in improving the insulation performance while maintaining a high slot fill rate. After the supply voltage is increased to 800 V, the design of insulation coordination such as electrical clearance and creepage distance should also be adjusted and strengthened [12-13].
4.2.3 Impedance matching and harmonic suppression
Under normal application conditions, the magnitude of the overvoltage at the motor end is proportional to the reflection coefficient at the motor end and the inverter end, the rise time of the PWM pulse, and the length of the high-voltage connecting cable. As the length of the busbar between the motor and the inverter increases, the amplitude of the overvoltage increases and the oscillation frequency decreases. When the length of the busbar increases to a certain length, the amplitude of the overvoltage is about twice the square wave pulse voltage , in order to suppress harmonics, the length of the high-voltage busbar should be shortened as much as possible. In order to eliminate the voltage reflection at the motor terminal, passive filtering technology can be used to match the characteristic impedance of the cable between the motor and the inverter and the motor. There are 3 impedance matching methods: adding a first-order resistance-capacitance circuit (Resistor-Capacitance circuit, RC) filter at the motor input end; adding a reactor at the output end of the inverter (reducing dv/dt); changing the cable characteristic parameters to reduce the motor The oscillation frequency of the terminal voltage. In order to suppress the overvoltage, a low-pass filter can also be set at the output of the inverter to reduce the dv/dt of the output pulse voltage, thereby reducing the amplitude and high frequency response of the overvoltage at the motor terminal.
4.3 Inhibition of electrical corrosion in high-speed bearings
The voltage source inverter output of modern PWM variable frequency power supply only has two states of high level and low level. With only 2 output states, it is impossible to produce a perfectly symmetrical three-phase waveform, so an unbalance occurs, producing very large common mode voltages between the motor windings and case ground, with rapid changes in voltage amplitude dv/dt. These factors lead to the addition of various forms of bearing current through multiple paths of coupling, resulting in bearing electrical corrosion.
4.3.1 Capacitive bearing currents
The bearing voltage caused by the common mode voltage division is small compared to other shaft currents.
The high-frequency equivalent circuit of the motor is shown in Figure 6, where:
Figure 6 High-frequency equivalent circuit of the motor
Cwf is the capacitance between the high-voltage stator winding and the stator core of the ground potential, each phase value;
Cwr is a capacitor connected in parallel between all three phases between the rotor surface and the stator winding;
Crf is the capacitance between the surface of the rotor and the top air gap on the surface of the stator core;
Cb is the capacitance of the bearing oil film;
vb is the bearing voltage, defined as the potential difference between the inner and outer rings of the bearing;
vY is the neutral point-to-ground voltage of the motor winding, which is also the common-mode voltage (the arithmetic mean value of the three-phase voltage).
The calculation formula of bearing voltage is as formula (2), and the formula of capacitive bearing current is as formula (3):
In the formula, vb is the bearing voltage; vY is the common-mode voltage; BVR is the ratio of the bearing-to-ground voltage to the common-mode voltage of the motor; Cwr is the three-phase parallel capacitance; Crf is the capacitance between the rotor and the stator; Cb is the capacitance of the bearing oil film; Ib is the capacitive bearing current; dvb/dt is the change rate of the bearing voltage to time.
4.3.2 Electrostatic discharge current
The common-mode source charges the bearing through a capacitive divider, causing a discharge current pulse when the threshold voltage is exceeded.
4.3.3 Circulating bearing currents
The higher phase voltage change rate dv/dt produces a relatively large high-frequency current, which induces a circular magnetic flux, which in turn induces a high-frequency shaft voltage, which in turn causes a circulating bearing current [14-15].
According to the generation mechanism of the bearing current, the ratio of the bearing-to-ground voltage to the common-mode voltage of the motor is defined as BVR. After the voltage platform is increased from 400 V to 800 V, the common-mode voltage will increase significantly, the shaft current will increase, and the problem of bearing electro-corrosion will become more prominent. There are many ways to suppress the shaft current, and each individual solution has its own advantages and disadvantages, and there are limitations in eradicating the problem of bearing electrical corrosion by relying on a certain method alone. A reliable and effective solution is a combination of "reduction, dredging, and blockage" and comprehensive treatment (Figure 7)
Figure 7 Bearing current suppression technology
4.4 Application of Automotive Grade Silicon Carbide (SiC) Power Devices
Among silicon (Si) material power devices, the higher the withstand voltage device is, the greater the on-resistance per unit area (increases at a ratio of about 2 to 2.5 powers of the withstand voltage value), so IGBTs are mainly used for voltages above 600 V. and other minority carrier devices (bipolar devices). Si IGBT injects holes as minority carriers into the drift layer through conductivity modulation, so the on-resistance is smaller than that of Si MOSFET, but at the same time, due to the accumulation of minority carriers, tails will be generated during Turn-off. Current, resulting in a huge switching loss, the resulting heat will limit the high-frequency drive IGBT.
When the power supply voltage level of the electric drive system is increased to 800 V, it is necessary to increase the withstand voltage of the power devices used in the inverter to 1200 V. At this voltage level, SiC MOSFET has more comprehensive technical advantages than Si MOSFET and SiIGBT, see Table 5.
Table 5 Physical properties of mainstream semiconductor materials[16-17]
Based on the inherent material properties of SiC, SiC MOSFET has four major advantages of high withstand voltage, low on-resistance, high frequency resistance, and high temperature resistance.
(1) The insulation breakdown field strength of SiC material is 10 times that of Si, so compared with Si devices, it is possible to realize high withstand voltage power devices above 600 V with a drift layer with higher impurity concentration and thinner thickness (Fig. 8).
Figure 8 Comparison of power withstand voltage between Si-based power devices and SiC[18-19]
(2) The impedance of high withstand voltage power devices is mainly composed of the impedance of the drift layer. Under the same withstand voltage value, SiC can obtain devices with lower standardized on-resistance (on-resistance per unit area). Theoretically, for devices with the same withstand voltage, the drift layer resistance per unit area of SiC can be reduced to 1/300 of that of Si. Therefore, there is no need for conductivity modulation, and there is no need to adopt a bipolar device structure such as IGBT (the on-resistance becomes lower, and the switching speed becomes slower), and the majority carrier device (MOSFET) of the high-frequency device structure can A device that has the advantages of low on-resistance, high withstand voltage, and high-frequency fast switching. Unlike IGBT, SiC-MOSFET has no turn-on voltage, so it can achieve low conduction loss in a wide current range from small current to high current, as shown in Figure 9. Moreover, MOSFET is a unipolar device in principle, does not generate tail current, can significantly reduce switching loss, and realize miniaturization of heat dissipation components.
Figure 9 Trend of on-resistance[20]
(3) SiC has a wider band gap, three times that of Si. The leakage current of SiC with large bandgap does not increase significantly at high temperature. Considering that SiC devices have low loss, low heat generation and much higher thermal conductivity than Si materials, SiC power devices can work stably even at high temperatures.
(4) SiC-MOSFET can be driven under high-frequency conditions where IGBT cannot work, so that the miniaturization of passive devices can also be realized [18-19].
When SiC MOSFET is used in a vehicle-mounted 800 V main drive inverter, compared with the use of IGBT, the efficiency can be significantly improved, mainly reflected in the high torque and low speed range of the inverter, which can reduce the power consumption of the vehicle by 6%[ 20].
4.5 Boost regulator technology
The step-up voltage regulator is the key technology of the hybrid electric drive system. In the future, the technology development platform of hybrid and pure electric products will be modularized, and the upper limit of the voltage regulation of the hybrid voltage booster is likely to reach 800 V. The booster is arranged between the inverter and the power battery, as shown in Figure 10. The booster can increase the voltage of the power battery to realize the dynamic adjustment of the working voltage of the motor system within a certain range, and can also reduce the voltage of the inverter terminal to charge the power battery.
Figure 10 Electrical principle of dual-motor boost system[21]
The main advantages of adding a booster to the motor system are as follows.
(1) The output power of the motor system is decoupled from the battery voltage: through the on-demand adjustment of the working voltage of the motor system, the output power of the motor will not drop due to the decrease of the battery voltage, and the system output power capability can be effectively improved by increasing the system input voltage ;
(2) The efficiency of the motor system can be optimized by voltage to improve the cycle efficiency of the system operating conditions: the operating voltage of the motor system can be dynamically adjusted within a wide range to achieve the optimal match between the operating point and the high-efficiency area [21];
(3) Reduce the output power demand of the motor under the rated voltage of the battery, which is conducive to the miniaturization design of the motor.
It should be noted that for the electric drive system equipped with a booster, the design of the motor body should take the highest output voltage of the booster as the highest working voltage of the system. At the same time, the booster itself will bring new losses, and the optimal design of system matching and voltage optimization strategies has a direct impact on the effect of the booster in the system.
4.6 High frequency electromagnetic interference suppression
In the application of variable frequency AC motors driven by Si-based inverters, since the rise time of the inverter PWM output voltage square wave pulse is very short (0.2-0.4 μs), the corresponding equivalent upper limit frequency is f=1/(π· trise), and its corresponding spectrum can reach 0.8-1.6 MHz. Compared with the traditional power frequency AC motor drive, the problem of high-frequency electromagnetic interference (Electro Magnetic Interference, EMI) has emerged.
Although the use of SiC MOSFETs in 800 V systems can significantly improve system efficiency and power density, due to the faster switching speed and higher switching frequency of wide bandgap semiconductor devices, it means that the dv/dt in the system and di/dt are higher, which further aggravates high-frequency electromagnetic interference. The EMI generated during the actual operation of SiC-based inverters is more serious than that of traditional Si-based inverters.
By analyzing the relationship between the common-mode EMI of the motor drive system and the switching behavior of SiC MOSFETs, it is found that the switching frequency is the main factor affecting the common-mode EMI of the system, the higher the switching frequency, the stronger the high-frequency interference; No effect, the shorter the switching time in the high-frequency band, the greater the amplitude of the system EMI spectrum; the higher the power supply bus voltage, the greater the amplitude of the high-frequency harmonics of the system EMI spectrum, and the richer the harmonic components.
Scholars at home and abroad mainly consider the interference source, interference propagation path and disturbed equipment to suppress electromagnetic interference (Figure 11) [22-23].
Figure 11 EMI suppression strategy [22-23]
Changing the switching characteristics of SiC MOSFETs has a significant impact on the high frequency EMI of the system. By optimizing the resistance of the gate drive resistor and adjusting the switching speed, the high-frequency EMI intensity can be reduced while ensuring the system efficiency; by properly adjusting the switching frequency, the overall power density can be reduced while ensuring the high power density of the system. EMI generated during system operation; by adding a resistor-capacitor circuit absorption loop in the circuit, high-frequency switching oscillations can be effectively suppressed and the high-frequency EMI intensity of the system can be alleviated [24].
Reasonable design and adding EMI filter configuration can also significantly reduce the system EMI intensity. During the design process of the EMI filter, many factors such as filter insertion loss, magnetic component characteristics, and common mode choke parasitic parameters should be fully considered. For example, literature [25] designed an EMI filter for SiC inverter applications, as shown in Figure 12.
Figure 12 EMI filter topology and parameters[25]
The motor control PWM strategy also has an impact on the EMI intensity. The research results show that, through the random PWM control strategy, the EMI intensity can be reduced, but the system loss and current ripple will be increased [24].
4.7 Integrated integration and control of driving and charging
BYD proposed a three-phase four-wire motor boost charging system architecture based on multiplexed power devices to achieve boost charging. In terms of power circuit topology design, the electric drive system and the DC boost charging system are deeply integrated, and the three-phase bridge arm of the inverter and the three-phase winding of the motor are multiplexed to form a typical Boost boost circuit. Charge the power battery after controlling the pump to increase the voltage of the charging pile. The time-division multiplexing of the driving and charging conditions is realized through the motor neutral point lead-out line and the relay-inductor-capacitor circuit, as shown in Figure 13.
Figure 13 BYD high-power motor boost charging topology circuit[26-28]
The use of a high-voltage topology that integrates drive and charge avoids the cost disadvantages of an independent step-up DC converter, but simultaneously brings about the problems of increased motor loss and safe torque output during charging. It is necessary to comprehensively use the in-phase and out-of-phase coordinated control technology of the three-phase bridge arm of the power module to decouple the control of the three-phase current and the neutral wire current of the motor. When charging starts, it operates in the out-of-phase control mode to suppress the amplitude of the motor neutral ripple current and reduce electromagnetic interference; in the charging process, it operates in the same phase control mode to suppress the frequency and amplitude of the three-phase ripple current of the motor and reduce the The core loss of the motor stator and rotor. At the same time, through the real-time torque estimation method based on the accurate detection of three-phase current, the zero torque output function safety during the boost charging process of the electric drive system is ensured.
Huawei also adopted the idea of multiplexing motor windings and power devices to propose an integrated technology solution for driving and charging [29].
4.8 Charge Pump Standalone Booster
The Porsche Taycan is independently configured with a charge pump booster, also known as a switched capacitor voltage converter, which is a DC converter that uses so-called "pumping" capacitors instead of inductors for energy storage. The basic principle is to generate a high voltage through the accumulation effect of the capacitance on the charge, so that the current flows from a low potential to a high potential. That is, after charging the capacitor, the capacitor is disconnected from the charging circuit to isolate the charged charge, and then connected to another circuit to transfer the just isolated charge. The boost function of the charge pump has been used in many low-voltage MCU (Microcontroller Unit, MCU) chips in the past.
The charge pump uses capacitors as switches and energy storage elements. Compared with inductive boosters that use inductors as energy storage elements, the main advantages of charge pumps are as follows: high efficiency, small size, low quiescent current, wide output voltage adjustment range, Low electromagnetic interference, simple hardware circuit. At the same time, the integration of capacitors is easier and cheaper than the integration of inductors.
Figure 14 is a charge pump booster with 2 times boost ratio. Uo=2Ui. In the actual charging of the 800 V system, assuming that the required charging voltage is 900 V, you only need to send a request to the charging pile for 1/2 of the actual required voltage (that is, Ui=450 V), and then increase the charging pile voltage through the charge pump The charging voltage of Uo=900 V can be obtained. Therefore, it is compatible with ordinary fast charging piles on the market.
Figure 14 2x boost ratio charge pump booster[30]re
5. Conclusion
(1) The electric drive system adopts an 800 V high-voltage platform, which significantly improves the comprehensive output performance in the medium and high-speed areas, and can meet the user's demand for super fast charging, but also greatly increases the cost of product materials. It is expected that the 800 V electric drive system will It is mainly equipped with mid-to-high-end models.
(2) More and more brands are planning 800 V high-voltage platform electric drive products, which have been mass-produced in the past two years. The country is also starting to deploy super charging piles, with a maximum output voltage of up to 1 500 V. With the improvement of high-voltage charging infrastructure in the future, the vehicle end will no longer need to be equipped with a booster charger.
(3) The technical framework of the 800 V high-voltage platform is becoming more and more mature. In the past two years, relevant technical standards such as voltage levels and conductive charging devices for electric vehicles need to be upgraded simultaneously.
