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In each of the past years, the automotive industry has brought newer and more sophisticated high-end technologies. That is to say, with the promotion of these technologies, unprecedented strict emission regulations have brought higher demand to the car's power supply. It is precisely under these influences that 48V electronic systems are spreading in the automotive world just like wildfires. Some experts predict that by 2025, one fifth of cars sold will carry 48V electronic systems, which will build a new grand blueprint. But we must admit that the 48 system is not new technology.
After conducting an in-depth conversation with the relevant principals of Delphi and the mainland's two major automotive suppliers, I have an in-depth understanding of how the 48V system works and why it is so popular. There are two main reasons: The first, and most important, is to meet the strict emission standards set by the government; the second is to give cars more power. 
Enhance the power load <br> <br> in the past ten years, car manufacturers have been using more and more high-tech, high-efficiency new technology to replace the traditional mechanical parts. Such as: electric assisted direction, electric brake vacuum pump and electric water pump. Next, car manufacturers introduced a series of new technologies such as infotainment systems, adaptive cruise control, lane departure warning systems, and blind spot monitoring into the car. Plus traditional seat heating, heated steering wheel and heated windshield.
In this environment, the standard 12V electronic system becomes more and more stretched. The 48-volt system was gradually put on the agenda to help meet the growing demand for cars. This trend is increasingly evident in luxury cars.
For example, Bentley Bentayga uses a 48V battery to drive the electric anti-roll bar system for better control. Audi also uses the same battery pack to power the electric booster.
Mary Gustanski, vice president of engineering at Delphi, said that the latter’s technology will greatly help improve the car’s acceleration capability. The company's "E-charger" was applied to Honda's new Civic, allowing the car to start and stop the car at very low engine speeds.
How does the 48V system work?
Before talking about the 48V system, we must first understand its concept.
The so-called 48V system refers to a low-cost fuel-saving technology solution jointly promoted by several German vehicle and component manufacturers. The system is a low-hybrid system, and it can also be seen as an upgraded version of the start-stop system. The system has a voltage of 48V. Instead of a conventional lead-acid battery, a power-type lithium ion battery with an energy less than one kWh is used instead of a conventional starter motor and generator. It not only has the function of idle start and stop, but also has the function of engine stop glide, glide and brake energy recovery, acceleration assist and electric cruising. More importantly, the cost of bicycles will not exceed RMB 5,000.
Although everyone is talking about the 48V system nowadays, basically the lights, engine parts, and car entertainment information systems on our cars are all 12V systems used.
However, unlike the practice in the industry that was completely replaced by 42V systems in the 1990s, the knowledge of the 48V system is intended to be an important supplement to 12V and to explore a mixed solution. In other words, the new motor and 48V battery are added to the traditional internal combustion engine and 12V battery as a powerful supplement. This is similar to the system you see now at GMBASHybrid, BuickLaCrosse, and SaturnAura.
Like the old GM powertrain, many new dual-voltage hybrid designs (like RenaultScinic's 48V systems) consist of three main components: an MGU (Motor Generator Unit), a DC/DC converter, and a high-voltage battery. Here, the MGU can replace the traditional alternator driven by the front-end auxiliary machine, and the role of the DC/DC converter and the battery is also increasingly important.
That is, the 48V system is relatively cheap and easy to implement. "This can be 50% to 70% of the benefits at 30% cost," Gustanski said. This 50% to 70% increase can save 15% fuel, he continued.
The mainland group also agrees with this view. They said that in their initial NEDC environmental test, they could also get 13% fuel savings, and in real applications, this data may reach 21%. This is very amazing.
Lithium-ion batteries and DC/DC converters
Delphi's prototypes demonstrated at this year's CES show included batteries, DC/DC converters, fuses, and battery controllers. They occupy little space. In practical applications, they are hidden.
The batteries used in Delphi's and mainland's 48V systems are lithium cells. The size of the battery is only as large as the shoebox (black box in the figure above). The battery pack below 1Kwh transfers energy to a 12V lead-acid battery. Of course, this is achieved with a DCDC converter (above the silver box with a fan). This is to reduce the voltage and meet the power supply requirements of the 12V equipment on the vehicle.
Why do I need a 48V battery? Gustanski said that in the final analysis it is an issue of efficiency and cost.
A 48V battery can support four times as many car accessories as a 12V battery, which means that you can use this battery to power more devices at the same time. For example, fans, electric boosters, pumps, and compressors. In this way, you can make the product more efficient. In addition, this has greatly improved the size and weight of the electronic harness.
Gustanski also admits that higher voltages have more influence.
Under federal standards, in automotive electronic systems, if the voltage is higher than 60V (the official high voltage), it will bring a higher standard of shielding, conduit and connectors, which will inevitably bring about greater costs. . Keeping the voltage below this voltage means that the cost of this mild hybrid system can stay between $800 and $1,200.
Also, as Gustanski said, according to the "rules of thumb", the cost of car manufacturers' investment in MPG's fuel saving technology has the expectation that the cost per one percentage point increase will be 50 to 100 US dollars. This mild hybrid cost is the product that meets the demand.
<br> <br> motor-generator set and alternator as an electric generator connected to the crankshaft of the engine via a belt. The 48V unit is usually liquid-cooled, so there will be a special tensioner to accommodate the fact that the crankshaft will be used by the MGU.
In the first example, an approximately 10kW unit acts like a motor. With an inverter, it can draw current from a 48V lithium battery, which drives the motor. The motor transmits power to a gasoline or diesel engine via a conveyor belt and "ignites" it. This application can also quickly "ignite" the engine (12V system requires a cold start) when it is started or stopped. This will increase the torque by about 100, which will improve the acceleration performance (especially when starting and stopping). Transmitting the calculated torque pulses to the engine can also reduce the vibrations at startup and stop, or reduce the engine load and reduce fuel consumption.
This unit not only acts as a motor, transmitting torque to the crankshaft, but as the name suggests, it is also a generator. After receiving the torque, it will charge the 48V battery pack again. This will not only be able to be charged by a belt (like a conventional AC motor) when the engine is working. After the engine is turned off, it can also be charged when taxiing and braking.
This means that the internal combustion engine can cut off the fuel supply, and at the same time, the wheel can drive the internal combustion engine through a locked torque converter. The conveyor belt of the engine crankshaft then drives the unit, which also powers the 48V battery.
Therefore, this unit can not only start the car seamlessly when starting and stopping, but also perform the charging of the alternator. The engine load can be reduced more by utilizing the torque on the crankshaft. Of course, this also allows regenerative braking.
Different levels of mild hybrid system <br> <br> Delphi MaryGustanski told me that they need to focus on a mild hybrid system (which collectively P0 mild hybrid system) MGU drive, but these low-cost systems for EV to That is a shortcut, so their next goal is the P2 system.
The so-called P2 system, like the Mercedes-Benz "Mercedes' inline starter generator" system, is relatively expensive. At the same time, its application will also bring new changes to the interior design of the car (for example, the current motor-generator unit is between the engine and the conveyor belt), and it will also affect the clutch and other accessories. The goal of P2 is to allow the motor to provide kinetic energy directly to the wheels without the need for an engine. This will greatly increase efficiency.
Continental P2 system has a power transmission system between the engine and the transmission system. And two parts are separated by two clutches. The MGU is placed on the other side and provides torque through the belt.
In order to provide electric energy only to the car by electricity, rather than by driving a non-running engine, the clutch on the engine side needs to be opened. The motor drives the transmission input shaft through the belt and the power transmission pulley system.
When the application starts and stops on a hot day, both clutches will open, so that the unit can transmit kinetic energy to the air-conditioning compressor without having to pass a moving car or turn the engine.
Making space for P2 is an important task. We will find that the components of this system that are better than the P0 system will soon be loaded into global cars in different ways. This purely electricity-driven approach also allows air conditioners to run when the engine is stopped. This will not only lead to better fuel economy, but also a more comfortable experience.
Everything is for higher efficiency <br><br> Mainland and Delphi related personnel told me that the 48V system has become more and more popular, and can mainly be attributed to the following factors: that is to meet the fuel economy and carbon dioxide emissions standard. Especially in Europe and China, these two points are particularly concerned. By 2020, the former will bring 95 grams of CO2 per kilometer, and the latter will reach 117 grams of CO2 per kilometre by 2021. The United States’ own MPG demand shows that by 2025, the CO2 emissions per kilometer will be 101 grams.
The replacement of the 12-generation system by the 48V system brings not only cost savings, but also the need for emission reductions. At the same time, the efficiency gains brought by pumps and fans at high pressures are also very obvious. More importantly, the 48V system can provide more power to meet the increasing demand for a variety of automotive functions, while also liberating some of the previous smart engine-driven devices.
For example, traditional water pumps and air conditioners are the most obvious changes.
For example, in a winter, the car you are driving is climbing at 4,000 rpm. In a traditional car, an engine-driven water pump sends a lot of coolant to the engine. But in fact, because the external environment is also very low, so does not need coolant to help cool the engine. So if we are using electric pumps, this problem can be avoided.
Gustanski gives another example. When a car is cruising at a high speed and a high speed, if it can be used to drive the air conditioner, it does not need the practice of a conventional car, resulting in a high speed of the air conditioner compressor at such a high engine speed. In other words, the advent of this new system will enable certain parts of the car to operate on demand.
Gustanski even mentioned that using a 48V to quickly heat the catalyst to diesel vehicles reduces emissions.
There is no doubt that the 48V car system will become mainstream. The IHS report even shows that by 2025, the market capacity of a 48V system will increase by a factor of nine, and around 14 million vehicles will be introduced into the system by that time.
This is a good thing for suppliers such as Delphi and the mainland. For consumers, this is also a good thing. This not only brought about a better fuel economy, but also brought more and better electronic experience. It also improves performance. Of course, the reduction in costs is the more direct advantage.