When it comes to 800V, today’s car manufacturers mainly promote the 800V fast charging platform, and consumers subconsciously think that 800V is the fast charging system.
Actually, that’s a bit of a misunderstanding. Strictly speaking, the 800 V high-voltage fast charging is just one of the features of the 800 V system.
In this article, DiskMFR intends to systematically show the reader a relatively complete 800V system in five dimensions, including:
- What is the 800V system in the new energy vehicle?
- Why is 800V being introduced today?
- What intuitive benefits can the 800V system bring today?
- What are the difficulties in the current application of the 800V system?
- What does the possible load configuration look like in the future?
01. What is The 800V System in the New Energy Vehicle?
The high voltage system includes all high voltage components on the high voltage platform. The figure below shows the high voltage components of a typical New Energy EV equipped with a 400V water-cooled platform voltage battery pack.
The voltage platform of the high-voltage system is derived from the output voltage of the vehicle battery pack.
The specific voltage platform range of different all-electric models depends on the number of monomers in the series of each battery pack and the monomer category (ternary, lithium iron phosphate, etc.).
Among them, the number of 100-string ternary monomer batteries is about 400V high voltage.
We often say that 400V platform voltage is a broad term. Take the Krypton 001 400V polar platform as an example. Width is close to 100V (about 350V-450V).
Under the 400V high-voltage power platform, all parts and components of the high-voltage system work under the 400V voltage level, and the design, development, and parameter verification are carried out according to the 400V voltage level.
In order to realize the complete 800V high-voltage platform system, 800V battery packs must first be used in the battery pack voltage, which is equivalent to about 200 ternary lithium batteries in series.
The second is that the motor, air conditioner, charger, 800V DCDC bracket, related wiring harnesses, high voltage connectors, and other high voltage circuit parts are designed, developed, and verified according to the 800V requirements.
In the development of the 800V platform architecture, in order to be compatible with the 500V/750V fast charging batteries on the market, the pure 800V trams will become booster DCDC modules of for some time 400V to 800V.
Its task is to decide in time whether to activate the booster module to charge the 800V battery according to the actual voltage capacity of the load cell.
According to the combination of cost performance, there are roughly two types:
- Full 800V platform architecture.
All parts of the vehicle in this architecture are designed for 800V.
- High-cost performance part 800V platform architecture.
Some 400V parts are retained: As the current cost of 800V power switching devices is many times that of 400V IGBTs, the main motor factory is motivated to buy 800V components (e.g. motors). use to balance overall vehicle cost and energy efficiency while driving. and reserve some 400V components (such as electric air conditioners and DCDC) for the most important and required propulsion systems.
Reuse Motor Power Components – Since no propulsion is required during charging, cost-conscious OEMs reuse power components in the rear bridge motor driver for 400V-800 Boost DCDC.
02. Why is 800V being introduced today?
During today’s daily driving of purely electric models, around 80% of the power is consumed in the drive motor.
The inverter is the engine controller that controls the engine, it is one of the most important components in the car.
In the age of Si-IGBT, the 800V high-voltage platform has little efficiency improvement and insufficient application performance.
The efficiency loss of the drive motor system is mainly composed of two parts: motor body loss and inverter loss:
The first part of loss – motor body loss
- Copper loss – Heat loss in motor stator windings (copper wires)
- In systems using magnetic forces in motors, the heat loss (heat in joules) is caused by eddy currents in the iron (or aluminum) parts of the motor due to changes in the magnetic force.
- Dispersion loss is attributed to the loss caused by the irregular flow of charge
- The wind friction loss
The second part of loss: motor inverter loss
- Conduction loss
- Switching loss
Before the third generation of SiC MOSFET power semiconductors is mature, the power components of new energy vehicles such as B. the drive motor, Si-IGBT as an inverter switching device. The support voltage level is mainly about 650V. IGBT with the highest voltage level is mainly used in power grids, electric locomotives, and other non-consumption occasions.
From the point of view of feasibility, the new energy car can theoretically use the IGBT with a voltage level of 1200V as the power switch of the 800V motor driver, and the 800V system will be developed in the IGBT era.
From a cost-performance perspective, the 800V voltage platform has a limited improvement in motor body efficiency, and the continued use of 1200V IGBTs has no improvement in motor converter efficiency, which accounts for most of the losses, but brings a number of developments with associated costs. Most car companies don’t have the power to apply the 800V platform in the IGBT era.
In the era of SiC MOSFETs, the performance of 800V systems began to be refined due to the development of key components.
After the advent of third-generation silicon carbide power devices made of semiconductor material, it was of great concern because of its excellent characteristics. Combines the advantages of high-frequency Si MOSFET and high-voltage Si IGBT:
- High operating frequency – MHz level, higher modulation freedom
- Good voltage resistance – up to 3000 kV, wide application scenarios
- Good temperature resistance – stable operation under the high temperature of 200℃
- Small integrated volume – higher operating temperatures reduce the volume and weight of the radiators
- High operational efficiency: The use of SiC power devices improves the efficiency of power components such as B. motor inverters, due to reduced losses. Take the Smart Genie as an example below. Under the same voltage platform and basically the same roadworthiness (almost no difference in tire weight/shape/width) they are all Genie engines. Compared with IGBT inverters, the overall efficiency of SiC inverters is improved by about 3%.
Note: The actual improvement degree of inverter efficiency is also related to the hardware design capability and software development of each company.
Early SiC products are limited by SiC wafer growth technology and chip processing capability. The current capability of SiC MOSFETs is much lower than that of Si IGBTs.
In 2016, a Japanese research team announced the successful development of a high-power density inverter using SiC devices and later published the results in IEEJ (Transactions in Electrical and Electronic Engineering, Institute of Electrical Engineers, Japan). At that time, the maximum output power of the inverter was 35kW.
In 2021, with technological advancement, the mass production of SiC MOSFETs with a voltage of 1200V and current capacity has improved year by year. They have been shown to be able to adapt to more than 200kW power products.
At this stage, the technology is starting to be used in real cars.
On the one hand, the performance of power electronic devices tends to be ideal. SiC power devices are more efficient than IGBTs, which can withstand a platform voltage of 800V (1200V) and have been developed for power capacity in excess of 200kW in recent years.
On the other hand, the advantages of the 800V high-voltage platform are visible. Voltage doubling provides higher vehicle charging power ceiling, lower system copper loss, higher motor-inverter power density (characterized by the same motor torque and higher power);
Third, the new energy market to increase the volume. The consumer side is looking for high mileage and faster energy replenishment speed, and the business side is striving to show the powertrain difference in the new energy market.
The above factors finally led to the large-scale research and application of the new 800V high-pressure platform in the past two years. 800V platform models currently on the market include Xpeng G9, Porsche Taycan, etc.
In addition, SAIC, Gekrypton, Lutes, Ideal, Tianji Automobile, and other automobile companies have also brought relevant 800V models to market.
03. What intuitive benefits can the 800V system bring today?
In theory, the 800V system can list many benefits, and I think the most intuitive benefits for today’s consumers are mainly the following two.
- One is longer and more solid battery life, which is the most intuitive benefit.
In terms of electricity consumption per 100km under CLTC conditions, it is conservatively estimated that the revenue generated by the 800V system will increase by 5%.
At high speeds, the 800V system is said to offer even more significant performance gains.
During the launch of the Xpeng G9, the manufacturer intentionally guided the media to conduct a high-speed endurance test, and many media reported that the Xpeng G9’s high-speed endurance performance rate was 800V (high-speed resistance/CLTC resistance * 100%) relative up.
The real effect of energy saving needs to be confirmed by the aftermarket.
- Second, make the most of the capacity of the existing charge stack.
The charging speed of the models with a 400V platform is almost the same compared to 120kW and 180kW charge cells.
With the help of the DC boost module of the 800V platform model, the existing low-voltage charging cell (200kW/750V/250A), which is not limited by the power grid, can be tapped directly from the total output of 750V/250A.
Note: The actual full voltage of Xpeng G9 is below 800V due to engineering considerations.
04. What are the difficulties in the current application of the 800V system?
The biggest difficulty in 800V applications is still inseparable from the cost.
This cost is divided into parts cost and development cost.
Start with component costs.
High-voltage equipment has high costs and high consumption. 800V full architecture in general, 1200 volt high-voltage power device design uses more than 30, SiC dual motor models at least 12.
As of September 2021, the retail price of 100A split-size (650V and 1200V) SiC MOSFETs is almost three times the price of the equivalent Si IGBT.
As of October 11, 2022, the retail price difference between two Infineon SiC IGBTs and MOSFETs with similar performance specifications is approximately 2.5 times. (Data source: Infineon website, October 11, 2022)
Based on the above two data sources, it can be estimated that the current SiC market is about three times the IGBT price difference.
Then there are development costs.
Because most 800V parts require redesign and verification, the testing effort is higher than for small iteration products.
Some test equipment from the 400V era cannot be applied to 800V products, and it is necessary to buy new test equipment.
The first OEMs to use the new 800V product typically share a larger portion of testing and development costs with component suppliers.
At the current stage, the main motor factory will choose the old supplier’s 800V products as a precautionary measure, and the old supplier’s development cost will be relatively higher.
According to an OEM automotive engineer’s forecast, the cost of a pure electric car with a full 800V architecture and two 400kW motors will increase between 10,000 and 20,000 yuan in 2021 when the system goes from 400V to 800 V and is upgraded.
Third, the 800V system is a low-cost performance.
Take as an example a pure electricity customer who charges a battery at home, assuming a charging cost of 0.5 yuan/kWh and power consumption of 20 kWh/100 km (typical power consumption for cruise ships), the customer can use the take advantage of the higher cost of the current 800-volt system to drive between 100,000 and 200,000 km.
Over the life of the vehicle, energy savings from efficiency improvements (a rough estimate of 3-5 efficiency gains based on high-pressure platforms and SiC efficiencies) do not cover price increases.
There are also market limitations for 800V models.
Economically, the 800-volt platform has no obvious advantages, making it suitable for high-performance B+/C-class models, where vehicle performance is ultimately at stake and is only relatively insensitive to a vehicle’s cost.
In this type of car, the market share is relatively small.
According to the data decomposition of the Passenger Association from January to August 2022, China’s price range analysis of new energy vehicles shows that the sales volume of 200,000-300,000 vehicles accounts for 22%, the sales volume of 300,000-400,000 vehicles accounts for 16%, and the sales volume of more than 400,000 vehicles accounts for 4%.
With the price limit of 300,000 vehicles, 800V models can capture about a 20% market share in the period when the cost of 800V parts does not decrease significantly.
Fourth, the 800V parts supply chain is not mature.
The application of the 800V system requires the reconditioning of the original parts of the high-voltage circuit. High-voltage platform battery, electric drive, charger, thermal management system, and parts, most of which are still in the development stage and have not been mass-produced. and application experience. OEMs have few suppliers, and mature products are prone to production problems due to unexpected factors.
Fifth, the 800V parts market verification is insufficient.
The 800V system uses many newly developed products (motor inverter, motor body, battery, charger + DC-DC, high voltage connector, high voltage air conditioner, etc.), which need to check separation performance, creepage distance, insulation, EMC, heat dissipation, etc.
Currently, the development and verification cycle of products in the domestic new energy market is short (in general, the development cycle of new projects in established joint ventures is 5-6 years, but the cycle of current development in the domestic market is less than 3 years). At the same time, the actual vehicle market inspection time of 800V products is insufficient, and the likelihood of subsequent after-sales is relatively high.
Sixth, the practical application value of the 800V system fast charge is not high.
By promoting 250kW and 480kW high-power (800V) super-fast charging, automakers often advertise the number of cities where charging cells will be deployed, deliberately misleading consumers into believing that they will Experience can enjoy any time after the purchased car, but the reality is not so good.
There are three main constraints as follows:
- 1. 800V charging pile to be added
Currently, the most common DC charging cell on the market supports a maximum voltage of 500V/750V, and the current limit of 250A cannot fully utilize the fast charging capacity of the charging system. 800V (300-400kW).
- 2. The maximum power of the 800V overcharging pile has constraints
Take Xpeng S4 (high-pressure liquid cooling) charging stack as an example, the maximum charging capacity is 480kW/670A. Due to the limitation of power grid capacity, the demo station only supports single-vehicle charging, which is the highest charging power the 800V Models can muster, with simultaneous charging of multiple vehicles in the peak power distribution will happen. Following the example of power supply professionals, schools with more than 3,000 students on the east coast apply the efficiency estimate of 80, approx. 800 V, 480 kW Surge Cell can be supported.
- 3. The investment cost of 800V overfilled piles is high
These are transformers, batteries, energy storage, etc. The actual cost is estimated to be higher than that of the power plant, and the possibility of large-scale deployment is low. The 800V overload is just the icing on the cake. What kind of charger layout can improve the charging experience?
05. What does the possible load configuration look like in the future?
Currently, the ratio of vehicle batteries (including public batteries and private batteries) in the total home charging battery infrastructure is still around 3:1 (based on data statistics from 2021).
With electric vehicle sales on the rise, there is a need to allay consumer concerns about charging. It is necessary to improve the ratio of vehicle stacks. Only in the target scene and fast charging scene can improve the charging experience and truly balance the grid charging by appropriately designing different specifications of fast charging batteries and slow charging batteries.
The first is destination charging, which requires no extra waiting time:
- Community parking lots: A large number of slow-filling orderly piles will be built within 7KW, and priority will be given to oil trucks to park in parking lots without new energy, which can meet the needs of houses and the laying cost is relatively low. The method of orderly control can also avoid exceeding the capacity of the regional power grid.
- Shopping malls/scenic spots/industrial parks/office buildings/hotels and other parking lots: 20KW fast charging is auxiliary power, many 7KW slow charging designs. End of development: low cost to fill slow stacks, no expansion costs; Consumer side: Avoid the fast charging scene and move the car after a short full charge.
Secondly, fast energy replenishment, how to save the overall energy consumption time:
- Motorway service station: maintain the current number of fast charges, strictly limit the upper limit of charging (such as 90%-85% of the peak) to ensure the charging speed of long-distance vehicles.
- Gas stations near highway junctions in major cities: Equipped with high-performance fast charging and strict charging cap limitation (e.g. 90% to 85% in peak). As a complement to high-speed rest areas, it meets the long-distance driving needs of new energy users and radiates the terrestrial charging needs of cities/communities. (Note: In general, the ground station is equipped with an electric capacity of 250kVA, which can support about two 100kW fast charging batteries at the same time.)
- Urban gas station/open parking lot: Equipped with high-power fast charging, it limits the charging ceiling. At present, CNPC is designing fast charging/power switching equipment in the new energy field, and more fast-charging battery stations are expected to be built in the future. (Note: The gas station/open parking lot itself is close to the curb and has obvious architectural features, which are handy for fee customers to quickly find the stack and exit the premises.)
Words in the end
Currently, the 800V system still faces many challenges in terms of cost, technology, and infrastructure. These difficulties are the only path for innovation and development of new energy vehicle technologies and industrial iteration, and the stage for engineers, investors, and policymakers to deploy their energy.
Chinese auto companies, with their rapid and efficient technical application capabilities, can achieve a large number of rapid applications of 800V systems and lead the trend in the field of new energy vehicles.
This generation of Chinese consumers will also be the first to enjoy the high-quality in-vehicle experience made possible by technological advances. It’s not like the gasoline car era anymore, domestic consumers are buying the old models of multinational auto companies, technology, or old technology. castrated products.
