Electric automobile DC charging system
Technical field
The present invention relates to electric vehicle engineering field, particularly a kind of electric automobile DC charging system.
Background technology
Electric automobile is to take vehicle power as power, the vehicles of a kind of new green environment protection travelling as power drive wheel with motor.The vehicle power of electric automobile generally carries out serial or parallel connection by plurality of groups of storage batteries and is arranged in a combination, and with this, improves the power supply capacity of storage battery.Electric automobile is due to less to the relative orthodox car of environmental impact, and its prospect is extensively had an optimistic view of.
The most widely used power supply of electric automobile is lead acid accumulator, but along with the development of electric vehicle engineering, lead acid accumulator is because energy is low, and charging rate is slow, and the life-span is short, is replaced gradually by other storage batterys.The power supply developing mainly contains sodium-sulphur battery, nickel-cadmium cell, lithium battery, fuel cell etc., and the application of these novel power supplies, for wide prospect has been opened up in the development of electric automobile.The effect of drive motor is to be mechanical energy by the electric energy conversion of power supply, by transmission device or direct drive of wheel and equipment.
Electric automobile charging station refers to the website into charging electric vehicle, similar to present gas station.Along with low-carbon economy becomes the theme of China's economic development, electric automobile charging station is as the important component part of new forms of energy strategy and intelligent grid, and one of the strategic new industry determined of State Council, will become the emphasis of Chinese Automobile Industry ' and energy industry development from now on.
Present charging system for electric automobile mainly contains following two kinds:
First, as shown in Figure 1, existing electric automobile charging station is most of to be given rechargeable battery powered by AC/DC convert charging device, by control system, control the charging voltage size of each AC/DC convert charging device, because a charging station generally has tens charge position, so control system is controlled very complicated.
Second, as shown in Figure 2, adopt centralized device for converting electric energy by the disposable DC bus that flows to of electrical network electric energy, then on DC bus, connect a plurality of DC/DC conversion equipments, be respectively rechargeable battery charging (storage battery), such charging station system control system with respect to the first charging system for electric automobile is controlled relatively simple.
Storage battery is in charging process, in order to shorten the charging interval, in the time of incipient, charging current and charging voltage are all larger, the prolongation in charging interval at any time, the temperature of storage battery can constantly rise, if continue to adopt charging voltage and the charging current starting, the life-span of storage battery will reduce greatly; So there is the charging system for electric automobile that charging voltage constantly changes, the technical scheme gathering is exactly the output voltage size that constantly regulates DC/DC converting unit (as Fig. 2), need control system constantly to control a plurality of DC/DC converting units, the complexity of whole like this control system is higher, because needs constantly change conducting turn-off time of thyristor, make whole system power consumption larger.
Summary of the invention
The technical problem to be solved in the present invention is: the existing control program complexity of passing through adjusting DC/DC converting unit output voltage size adopting for the prolongation rechargeable battery life-span is higher, and whole system power consumption is larger.
In order to solve above technical problem, technical scheme of the present invention is as follows:
Electric automobile DC charging system, comprises three-phase transformer, centralized electric energy converting unit, a N direct current convert charging unit, a N charging case; The input of described three-phase transformer connects electrical network electric wire, and the output of three-phase transformer connects the input of centralized electric energy converting unit, and the output of centralized electric energy converting unit connects DC bus; The input of each direct current convert charging unit connects DC bus; Also comprise N*N switch element, a N temperature sensor, a N current sensor, a N voltage sensor, controller unit;
The output of each direct current convert charging unit connects the input of N switch element simultaneously, and the output of N the switch element that each direct current convert charging unit connects simultaneously connects respectively the input of N battery case;
Temperature sensor detects the temperature of rechargeable battery;
Current sensor, voltage sensor detect respectively charging current and the charging voltage of each rechargeable battery;
Temperature sensor, current sensor, voltage sensor are electrically connected to controller unit;
Controller unit is controlled the disconnection of each switch element with closed.
Be more preferably technical scheme, described controller unit adopts MSP430 single-chip microcomputer.
Compare with prior art scheme, beneficial effect of the present invention: this system is by detecting temperature, charging current, the charging voltage of rechargeable battery, and adjust in time charging voltage, because thereby controller just changes charging voltage and the charging current of rechargeable battery by control switch unit, so whole system control is simpler; The power consumption of whole system is lower, more energy-conservation.
Accompanying drawing explanation
Fig. 1 is existing a kind of charging system for electric automobile principle block diagram.
Fig. 2 is existing another kind of charging system for electric automobile principle block diagram.
Fig. 3 is the principle block diagram of a specific embodiment of the present invention.
Embodiment
Below in conjunction with accompanying drawing, the invention will be further described.
As shown in Figure 3: electric automobile DC charging system, comprises three-phase transformer, centralized electric energy converting unit, 3 direct current convert charging unit, 3 charging cases, 9 switch elements, 3 temperature sensors, 3 current sensors, 3 voltage sensors, controller unit; The output voltage of 3 direct current convert charging unit is respectively 600V, 800V, 1200V.
The output of each direct current convert charging unit connects 3 switch elements, and the output of 3 switch elements that the output of each direct current convert charging unit connects connects respectively the input of 3 battery cases.
Switch element adopts relay to realize, and current sensor is mainly used in monitoring over-current phenomenon avoidance, and the present invention is mainly by voltage sensor monitoring voltage, and then diverter switch unit changes charging voltage.
Voltage sensor, current sensor are arranged at the input of battery case.
As for centralized electric energy converting unit, direct current convert charging unit and the control system that relates to, belonging to existing known technology is not described in detail.
The input of three-phase transformer connects electrical network electric wire, and the output of three-phase transformer connects the input of centralized electric energy converting unit, and the output of centralized electric energy converting unit connects DC bus; The input of each direct current convert charging unit connects DC bus, the output of each direct current convert charging unit connects the input of 3 switch elements simultaneously, and the output of 3 switch elements that each direct current convert charging unit connects simultaneously connects respectively the input of 3 battery cases; Temperature sensor detects the temperature of rechargeable battery; Current sensor, voltage sensor detect respectively charging current and the charging voltage of each rechargeable battery; Temperature sensor, current sensor, voltage sensor are electrically connected to controller unit; Controller unit is controlled the disconnection of each switch element with closed.
Wherein, controller unit adopts MSP430 single-chip microcomputer.MSP430 series monolithic is the single-chip microcomputer of 16, has adopted Reduced Instruction Set Computer Architecture, and why MSP430 single-chip microcomputer has ultralow power consumption, is because it has its distinctive feature reducing aspect supply voltage of chip and flexible and controlled operation clock.
The concrete control method principle of embodiment: if direct current convert charging cell mesh is respectively the first direct current convert charging unit, the second direct current convert charging unit, the 3rd direct current convert charging unit from left to right in Fig. 3; Battery case part is from left to right respectively the first battery case, the second battery case, the 3rd battery case.
If the output voltage of the first direct current convert charging unit is 600V, to be just first rechargeable battery charging, charging interval 0, detected temperatures 15 degree;
The output voltage of the second direct current convert charging unit is 800V, is being second rechargeable battery charging, has charged 30 minutes, and detected temperatures is 28 degree;
The output voltage of the 3rd direct current convert charging unit is 1200V, is being the 3rd rechargeable battery charging, has charged 30 minutes, and detected temperatures is 30;
At this moment controller unit is by control switch unit, allows the first direct current convert charging unit be the second battery case charging, and the second direct current convert charging unit is the 3rd battery case charging, and the 3rd direct current convert charging unit is the first battery case charging.
Above control method is an example, and the present invention has only been to provide a kind of electric automobile DC charging system, and the control method that this system is concrete can be adjusted according to actual conditions.
System of the present invention is adjusted charging voltage in time by detecting temperature, charging current, the charging voltage of rechargeable battery, has greatly extended the life-span of storage battery, makes charging safer; Because thereby controller unit just changes charging voltage and the charging current of rechargeable battery by control switch unit, rather than change charging voltage by changing the output voltage size of direct current convert charging unit, so it is very simple, more energy-conservation that whole system of the present invention is controlled.