The to segregation demand in 48V car application increases continuously. This is the method of a kind of compact, efficient, dovish, low noise, can keep apart 48V system through CAN interface.

 

Be today’s car to design is behavior of a kind of balance. Satisfying increasingly strict discharge standard and carry system and small tool to provide power for more and more cars between, need to provide high power for current car, in order to obtain efficient.

 

To realize the confluence of efficiency and power, engineer more rely on the system that runs 48V electric power to be united in wedlock with traditional engine burning gas, if mix motivation electric car (HEV) . The carbon dioxide that this kind of method can ensure car is contented and strict (CO2) discharge a standard, still can improve function and drive quality at the same time.

 

Although already had a lot of views about itself of system of double batteries car, but what the article pays close attention to is these combined-type 12 with a key in 48V system and the component that is ignored sometimes: Voltaic segregation. Voltaic segregation is used at noise of counteractive ground connection, be in with its the ground connection in system of connective 48 V disconnects or 12V system is protected when breakdown.

 

The article will discuss the demand that keeps apart in 48V car application, describe a kind compact, efficient, dovish the method with low noise, through controlling area network (CAN) interface keeps apart 48V system.

 

The necessity that the car electric current of use 48V batteries keeps apart

 

Although using 48V cell (it is lithium ion batteries normally) in car, traditional 12V lead acerbity batteries still can be control electron equipment and power supply of low power facilities. The system that runs on material of these two bad news needs each other to correspond. For example, 48V starts a dynamo to be controlled by engine controller, power supply of use 12V batteries. The ground connection of two systems receives car batholith repeatedly. Although from theoretic tell, two systems can join each other directly (graph 1a) , but as a result of the following reason, electric current keeps apart (graph 1b) be necessary from beginning to end almost:

 

Voltage of transient state ground: The ground connection of 12V system uses bolt to receive car batholith repeatedly directly. The ground connection of 48V module uses a few feet long cable to receive car batholith repeatedly. 48V system (if start dynamo or communication compressor) in the many switch electric current of existence, the inductance that combines ocean ground cable is characteristic, may cause noise of instantaneous ground connection, 3.3V of low pressure of very easy attaint or 5V communication signal. It is necessary that electric current keeps apart reliable to ensuring data to transmit.

 

The ground connection of 48V side disconnects: During fall in breakdown condition sometimes or be being safeguarded, the GND_48V in graph 1a may disconnect with chassis join. The 48V power source of module, turn and receive 48V batteries repeatedly, may in good condition still nondestructive. Below this kind of circumstance, all in-house node of 48 V system (the interface that includes 12V system) can drift 48V. This creates risk to 12V system, because port of its input, output is likely,not be the design is used at handling 48V. In graph 1b, same breakdown condition won’t create pressure to 12V system. Electric current lies between base to go up 48 now, normally rated tension is gotten high much (like 2.5 KV) .

 

Short circuit circumstance: In graph 1a, any in-house short circuit bring about 48V system possibly to handle occurrence 48V tension in the interface with 12V system. This kind of potential risk may endanger the many circuit that move on 12V power source, include to run crucial circuit to car safety. Voltaic segregation conduces to the 12V side that ensures any short circuit on 48V system won’t transmit car.

 

Graph 1. Between 12V and 48V system keep apart join with report directly

 

Use CAN interface keeps apart 48V system

 

Can realize electric current to keep apart through a variety of means, keep apart border in the different position scale inside the system. The graph shows the current method that implements segregation in CAN interface for a kind 2 times. The other place segregation in CAN interface and system has the keeps apart a passageway advantage that uses least measure- – require two segregation passage only can. This reduced cost and circuit board space.

 

Graph 2. What show the give a demonstration that the electric current between the 12V in using car to spend mixture power cable gently and 48V side keeps apart

 

Converter of segregation type DC-DC can offer VISO of segregation power source, for the certain part power supply of 48V system. Although 48V batteries discharges completely, VISO also can ensure the crucial part of digital isolator and 48V system has the power source that can be used at the operation. If GND_48V disconnects, VISO also can be used at condition of safety of 48V side park.

 

Already rolled out CAN of type of new-style and compositive segregation to send and receive now implement with segregation controller of type DC-DC power source shows, conduce to simplify the interface of segregation type CAN in 48V system. The graph is shown 3 times start a dynamo for 48V of a give typical examples. You can use similar segregation framework for other 48V system, if DC-DC converter, batteries manages,system, heater is mixed air compressor.

 

Graph 3. This 48V dynamo that start uses segregation type CAN to send and receive implement keep apart power source with push-pull type

 

Odd CAN sends and receive a compositive segregation type implement, be like heart state apparatus (TI) ISO1042-Q1 (graph 3) , high-pressured electric current segregation and high-powered CAN are sent and receive implement compositive, conduce to reduce circuit board area, improve sequential parameter at the same time. From the point of the angle of CAN, defer of small ring road and deflection use rate of CAN agile data to realize communication of high speed data. Segregation provides the immune power that disturbs with radiation to conducting. Redundant or aggrandizement segregation will offer additional protective surplus below breakdown condition.

 

When be used together with exterior transformer, the push-pull transformer driver such as the SN6505-Q1SN6505-Q1 of heart state apparatus (also show 3 times like the graph) can produce VISO_HV of segregation power source (inside the 10 limits to 15V) , for semiconductor of metallic oxide power supply field effect transistor (MOSFET) grid driver, can produce inferior VISO (3.3 to 5V limits inside) , for sheet piece machine and the digital side power supply that keep apart CAN parts of an apparatus.

 

Push-pull type develop attacks the structure uses switch of two low side. These switch are in alternant clock is phasic in guide, so that in the center cent receives segregation,power is transmitted continuously on transformer. Develop attacks the make a present of before the structure is used adjusts, output voltage passes transformer rate control purely. Attack with other pictures structural photograph is compared, permanent power is transmitted can produce lower peak value electricity, reduce thereby discharge and improve efficiency. Symmetrical driver still can prevent transformer saturation, form compact transformer thereby.

 

In 12V side, converter of DC-DC of blame segregation type or step-down implement can generate 5 V power source, send and receive for CAN implement power supply, also can keep apart the input voltage of type DC-DC converter as push-pull type at the same time. Step-down of the buy before using makes a system not sensitive to the change of power source of 12 V batteries, this kind of change may be caused by laden change. In addition, in inferior input voltage (5V Vs.12V) next operations can bring about transformer decrescent.

 

Conclusion

 

The factor considers all in ally in the car that voltaic segregation is power supply of use 48V batteries. Segregation is used at noise of counteractive ground connection, be in with its the ground connection in connective 48V system disconnects or 12V system is protected when breakdown. The give typical examples of the system that uses 48V power source in HEV includes starter – supercharger of dynamo, dynamoelectric turbine, electric pump, air conditioning, heater, dynamoelectric suspension and driver are auxiliary. CAN of compositive segregation type is sent and receive implement with be based on push-pull type to keep apart union of photograph of type DC-DC power source, can offer those who be used at keeping apart 48V system is compact, efficient, dovish and the technology of low noise.

(origin: Heart state apparatus)