The current design of hybrid electric vehicles (HEV) and pure electric vehicles (EV) is very compelling, but there is also a less obvious but significant development trend in the automotive industry: the addition of a 48V direct current (DC) bus to the powertrain. 48V is not only suitable for hybrid and pure electric vehicles, but more common internal combustion vehicles will also adopt this technology. From Figure 1, it can be seen that the market share of pure electric vehicles and hybrid vehicles is growing.
Figure 1: The electric vehicle market (both BEVs and HEVs) is expected to grow rapidly in the next few years, and 48V adoption will be a factor favoring growth (Source: Delphi Technologies)
Engineers and auto mechanics have been exposed to ubiquitous 12V batteries and auto parts since childhood (an industry standard that's been more than 100 years old), but don't need to worry that 12V systems aren't going away anytime soon, however in the foreseeable future 12V May coexist with 48V systems.Also read:lithium battery manufacturer
So what makes a 48V system unique? The answer needs to come from an electrical perspective, going back to Ohm's law, voltage drop (V=IR), power (P=IV), and power loss (P=I?R) According to the laws of physics, although the voltage drop (loss) increases linearly with the current, and the power loss increases with the square of the current, the transmission power needs to be determined by current and voltage. In short, outputting more power at a given voltage requires more power. Large current, and the larger the current, the higher the voltage drop, and the power loss cannot be recovered.
This is not a new development, solution providers in the power sector have known this for a long time, which is why they are using higher voltages, they are looking for better solutions for powering street lighting systems, homes and industrial sites, but Getting 12.6V (nominal) from a rechargeable lead-acid battery is a good compromise for an automobile, taking into account factors such as size, capacity (Amp-hours), cost, lifespan, and safety.
However, today's cars require more power than they did a few years ago, and in addition to basic functions such as the engine, lights, radio, electric sunroof, electric power steering, networking and infotainment, many other safety and convenience features are now integrated. Functions are usually classified as advanced driver assistance systems (ADAS). ADAS systems place higher requirements on batteries and require more power. Therefore, using 12V power to power various core components and peripherals will cause greater damage. current, however the way to keep the IR drop and I?R power loss at acceptable levels at 12V is to use thicker wires, more copper material and larger connectors, which in turn means cost, bulk The increase in the vehicle system will appear more crowded.
In this method, a 48V battery - as specified in the automotive standard LV148 - is used in addition to a 12V lead-acid battery (which provides a 3KW power rating), as shown in Figure 3. The 12V battery and the 48V battery will be used along with their power distribution harnesses, both batteries will provide energy output when power output is required, such as the 12V bus can provide power for ignition, lighting and infotainment systems, while the 48V bus will be responsible for the chassis Control systems, air conditioning, tuning suspension, recovering braking energy, driving electric superchargers and turbos, etc.Also read:72v 100ah lithium battery pack
Consider a basic component: starting the starter, how does the 48V battery change the basic structure of the engine starter to better enhance the start-stop effect, which is beneficial to reduce fuel consumption at traffic lights and stop waiting, further enhancing fuel efficiency . In most cars with only a 12V battery the battery powers the starter and the alternator acts as the charger, however a combination of 48V and 12V can provide up to 10KW of power. The starter motor and separate alternator are integrated into the starter generator Instead of an ISG or belt starter generator, the 48V lithium-ion battery and bidirectional DC/DC converter are packaged in a rugged box, which is essentially a mild hybrid system that works in tandem with an internal combustion engine. It can provide two-thirds the benefits, but only one-third the cost, with a 15% to 20% increase in economics.
Choosing 48V at the same time also raises two questions: Why not just go from 12V to 24V? Since higher voltages bring more benefits, why limit the voltage to 48V? There are many different answers to these questions.
About 10 years ago, the discussion about 24V was so intense that some major manufacturers even started to produce 24V connectors, switches, relays and other basic components. But the benefits of using 24V are not enough to justify this change. In addition, the debate over whether cars should completely phase out 12V batteries and use only 24V batteries, or let them coexist, has not been resolved.Also read:24v 200ah lifepo4 battery manufacturer
As for user safety issues above 48V, DC voltages above 60V are considered potentially unsafe in most regions, requiring special wiring considerations, safety locks, use of conduit, and physical shielding. Although a 48V system may actually peak slightly below 60V, it is considered safe, thus avoiding this aspect (note that for BEVs and HEVs the voltage associated with the main battery will be well over 60V) , so all safety rules and precautions are taken into account in the design), 48V is the highest level that can be achieved by traditional micro-hybrid systems, thus avoiding additional safety-related design issues.