CN102801202B - Automatic charging device of new energy electric automobile and control method of automatic charging device - Google Patents

Abstract

The invention discloses an automatic charging device for a new energy electric vehicle and a control method thereof, including a battery pack and a controller. On the terminal, the output terminal of the controller controls the internal combustion engine, and the internal combustion engine drives the generator to work. The electric energy output by the generator is processed by the charging circuit to charge the battery pack. During the control process, the internal resistance measurement method is used for charging detection. Its remarkable effect is: setting the vehicle internal combustion engine and generator to charge the car battery pack, avoiding the inconvenience caused by offline charging, using the internal resistance measurement method to detect the discharge state of the battery pack, and judging the best charging efficiency through the controller point, thereby controlling the work of the internal combustion engine, improving the charging and discharging efficiency of the battery pack, saving energy consumption, and prolonging the service life of the battery pack.

Description

New energy electric vehicle automatic charging device and control method thereof

technical field

The invention relates to the technical field of new energy electric vehicles, in particular to an automatic charging device for new energy electric vehicles and a control method thereof.

Background technique

In recent years, due to the extensive use of automobiles, the problems of energy shortage and environmental pollution have become increasingly serious. Therefore, my country vigorously advocates the development of new energy vehicles, especially electric vehicles with energy saving and environmental protection characteristics. The technology research and development of electric vehicles has become a research hotspot. At present, there is no single battery that can provide enough power for electric vehicles. The voltage of the battery driving the car needs to be as high as 300 volts. To obtain such a high voltage, it must rely on battery pack technology. During the use of the battery pack of the energy supply device of an electric vehicle, as the energy of the battery pack decreases, the voltage at both ends of the battery pack will also decrease, thereby reducing the driving ability of the car and reducing the safety performance.

Existing car batteries are generally charged offline, which takes a long time and is inconvenient to use; the battery is discharged too much, exceeding its optimal charging point, and the power utilization rate is not high, which seriously affects the service life of the battery pack. At the same time, the energy consumption of automobiles is large, and the power supply of a single battery pack cannot meet the requirements of long-distance driving of automobiles, which greatly limits the development of electric vehicles.

Moreover, the existing charging management system often directly adopts the voltage comparison method. When the output voltage of the battery pack is less than a certain rated voltage, it is the charging time of the battery. With the different loads, the discharge characteristics of the battery pack are often different. Similarly, only using the output voltage to judge, the management is not scientific enough.

Contents of the invention

In order to overcome the problems existing in the prior art, the object of the present invention is to provide an automatic charging device for a new energy electric vehicle and its control method, which can solve the defects caused by the off-line charging method and the voltage judgment method.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

An automatic charging device for new energy electric vehicles, including a battery pack and a controller, the battery pack provides power to the motor of the vehicle and the controller, and is characterized in that: the input end of the controller is connected to a charging detection module, and the charging detection module is connected to On the output end of the battery pack, the output end of the controller controls the internal combustion engine, the internal combustion engine drives the generator to work, and the electric energy output by the generator is processed by the charging circuit to charge the battery pack.

By setting the on-board internal combustion engine and generator on the car, the charging detection module is used to detect the discharge state of the battery pack. When the capacity of the battery pack is detected to be insufficient, the controller is used to start the internal combustion engine, and the internal combustion engine drives the generator to work. The electric energy output by the generator passes through After the charging circuit, the battery pack is charged. In this way, when the car is running, charging can be provided online in real time, avoiding the inconvenience caused by offline charging.

As a further description, the charging detection module includes an internal resistance detector, a voltmeter and an ammeter, the internal resistance detector and the voltmeter are connected in parallel at both ends of the battery pack, and the ammeter is connected in series at the output end of the battery pack.

Ordinary charging management often adopts the voltage detection method, and the voltage is collected at the output end of the battery pack. When the remaining power of the battery drops to a certain rated voltage, the internal combustion engine is automatically started, and the generator is driven by the internal combustion engine to charge the battery pack. Supplement the energy of the battery pack, extend the driving time of electric vehicles, and improve the efficiency of the battery pack.

However, according to the discharge characteristics of the battery pack, the discharge process is often divided into four stages. The initial capacity decays quickly, then the decay rate slows down, then the steady period of the decay rate continues to slow down, and finally the battery capacity rapidly decays.

Usually the battery capacity has decayed to 80% of the initial value, which is considered to be the end of life. The best charging and discharging efficiency point should be selected in the second half of the steady period, that is, before the lowest discharge voltage. Under different load operations, the discharge curve of the battery pack is different. The greater the load, the larger the output current of the battery pack, and the lower the optimal charging and discharging efficiency point. Therefore, the voltage monitoring method alone cannot manage the charging and discharging time of the battery pack well.

The present invention adopts the internal resistance measurement method, an internal resistance tester is arranged in the resistance measurement module, through the cooperation of the internal resistance test, the voltmeter and the ammeter, the internal resistance change of the battery pack is detected in real time, because the performance of the battery pack and the The capacity can be directly reflected by the internal resistance of the oil. As the discharge time increases, the internal resistance of the battery pack tends to rise gradually. When it is lower than a certain voltage, the internal resistance of the battery pack will increase sharply. Therefore, the monitoring The best charging time of the battery pack can be judged by the change of the internal resistance of the battery pack, so as to obtain the best charging efficiency.

As a further description, the battery pack is a lithium battery pack, a lead-acid storage battery or a nickel-metal hydride storage battery.

To further describe, the internal combustion engine is a gasoline engine, a diesel engine, a natural gas engine or an ethanol engine.

The above connection relationship, the present invention also describes the control method of the new energy electric vehicle automatic charging device, the method is carried out according to the following steps:

Step 1: Set the standard internal resistance value of the battery pack to R ₀ , turn on the power switch through the controller, and the battery pack supplies power to the car motor;

Step 2: the charging detection module detects the discharge state of the battery pack, and the controller obtains the voltage value of the voltmeter in the charging detection module as V, the current value of the ammeter as I, and the internal resistance value of the internal resistance detector as r, and according to Calculate the resistance of the battery pack as R;

Step 3: delay time T;

Step 4: The controller obtains the voltage value of the voltmeter in the charging detection module V', the current value of the ammeter I', and the internal resistance value of the internal resistance detector r', and according to Calculate the resistance of the battery pack as R';

Step 5: The controller calculates the internal resistance difference ΔR of the battery pack according to △R=R’-R;

Step 6: The controller judges whether ΔR/R ₀ is greater than k, where k is the critical coefficient of internal resistance increment of the battery pack:

If ΔR/R ₀ is greater than k, go to step 7;

If ΔR/R ₀ is less than or equal to k, go to step 9;

Step 7: The controller outputs the first control signal, starts the internal combustion engine to work, drives the generator to charge the battery pack through the internal combustion engine, and proceeds to step 8;

Step 8: The controller obtains the voltage value V' of the voltmeter in the charging detection module, and judges whether the voltage value V' is less than the maximum output voltage value Vmax of the battery pack:

If V' is less than Vmax, then enter step 7 to continue charging;

If V' is greater than or equal to Vmax, then enter step 9;

Step 9: The controller outputs a second control signal, shuts down the internal combustion engine, and returns to step 2 to continue monitoring the discharge state of the battery pack.

As a further description, the delay time T=30s, the value of the internal resistance increase critical coefficient k of the battery pack is 5%-20%, and the maximum output voltage value Vmax of the battery pack=12V.

The notable effect of the present invention is: setting the vehicle-mounted internal combustion engine and generator to charge the car battery pack, avoiding many inconveniences caused by the off-line charging mode, using the internal resistance measurement method to detect the discharge state of the battery pack, and judging the best by the controller The charging efficiency point is used to control the operation of the internal combustion engine, improve the charging and discharging efficiency of the battery pack, save energy consumption, and prolong the service life of the battery pack.

Description of drawings

Fig. 1 is a system block diagram of the present invention;

Fig. 2 is a schematic circuit diagram of the charging detection module in Fig. 1;

Fig. 3 is a control flow diagram of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1: a new energy electric vehicle automatic charging device, including a battery pack 1 and a controller 5, the battery pack 1 provides power to the vehicle motor 7 and the controller 5, the input end of the controller 5 is connected to There is a charging detection module 4, the charging detection module 4 is connected to the output terminal of the battery pack 1, the output terminal of the controller 5 controls the internal combustion engine 6, the internal combustion engine 6 drives the generator 3 to work, and the electric energy output by the generator 3 passes through the charging circuit 2 Charge the battery pack 1 after treatment.

The battery pack 1 can be a lithium battery pack, or a lead-acid storage battery or a nickel-metal hydride storage battery.

The internal combustion engine 6 can be a gasoline engine, or a diesel engine, a natural gas engine or an ethanol engine. The type of the internal combustion engine 6 can be determined according to the specific vehicle model, and its purpose is to convert the chemical energy of the fuel into kinetic energy, drive the generator 3 to work, and thereby charge the battery pack 1, as long as the internal combustion engine 6 can be ignited and controlled by the controller 5 , a wide range of applications.

By arranging the vehicle-mounted internal combustion engine 6 and the generator 3, the battery pack 1 can be charged when the hybrid electric vehicle is running, thereby prolonging the mileage of the hybrid electric vehicle, improving the service efficiency of the battery pack, ensuring sufficient power of the battery pack, and improving the efficiency of the battery pack. The load capacity and stability of hybrid electric vehicles.

As shown in Figure 2: in order to judge the best charging efficiency point of the battery pack 1, the charging detection module 4 includes an internal resistance detector, a voltmeter and an ammeter, and the internal resistance detector and the voltmeter are connected to the two ends of the battery pack 1 in parallel. terminal, and the ammeter is connected in series to the output terminal of the battery pack 1.

Because the load of the battery pack 1 is related to the speed of the automobile motor 7 and the working state of the on-board circuit, its load status will change dynamically. The load of the battery pack 1 is different, and its discharge characteristics are also different. By setting the ammeter and voltmeter, that is The resistance value of the load can be detected. According to the connection relationship shown in the figure, the load resistance value R _L = the detection value of the voltmeter V/the detection value I of the ammeter, because the value r measured by the internal resistance tester is the load resistance The value after the value R _L is connected in parallel with the internal resistance R of the battery pack, that is, 1/r=1/R _L +1/R, therefore, the internal resistance of the battery pack R=R _L *r/(R _L -r)=V* r/(VI*r), so that the controller 5 can monitor the change of the internal resistance of the battery pack 1 in real time. According to the discharge characteristics of the battery pack, when the internal resistance of the battery pack 1 changes suddenly, it proves that the battery pack 1 The capacity of 1 is insufficient, and it needs to be charged, so the controller 5 is used to control the internal combustion engine 6 to start, and the generator 3 is driven to work, and the generator 3 and the charging circuit 2 are used to charge the battery pack 1 .

As shown in Figure 3: combined with the above structure, the control method of the automatic charging device for new energy electric vehicles is carried out according to the following steps:

Step 1: Set the standard internal resistance value of the battery pack 1 to R ₀ , turn on the power switch through the controller 5, and the battery pack 1 supplies power to the automobile motor 7;

The standard internal resistance value of the battery pack 1 is R ₀ , which can be preset in the control algorithm through measurement during factory configuration, depending on the type of battery selected for the battery pack 1 .

Step 2: the charging detection module 4 detects the discharge state of the battery pack 1, and the controller 5 acquires the voltage value of the voltmeter in the charging detection module 4 as V, the current value of the ammeter as I, and the internal resistance value of the internal resistance detector as r, and according to Calculate the resistance value of the battery pack 1 as R;

Step 3: delay time T;

Step 4: The controller 5 acquires the voltage value of the voltmeter in the charging detection module 4 as V', the current value of the ammeter as I', and the internal resistance value of the internal resistance detector as r', and according to Calculate the resistance value of the battery pack 1 as R';

Step 5: The controller 5 calculates the internal resistance difference ΔR of the battery pack 1 obtained by two adjacent measurements according to ΔR=R'-R;

Step 6: The controller 5 judges whether ΔR/R ₀ is greater than k, where k is the critical coefficient of internal resistance increment of the battery pack 1:

If ΔR/R ₀ is greater than k, go to step 7;

If ΔR/R ₀ is less than or equal to k, go to step 9;

Step 7: The controller 5 outputs the first control signal, starts the internal combustion engine 6 to work, drives the generator 3 to charge the battery pack 1 through the internal combustion engine 6, and proceeds to step 8;

Step 8: The controller 5 obtains the voltage value V' of the voltmeter in the charging detection module 4, and judges whether the voltage value V' is less than the maximum output voltage value Vmax of the battery pack 1:

If V' is less than Vmax, then enter step 7 to continue charging;

If V' is greater than or equal to Vmax, then enter step 9;

Step 9: The controller 5 outputs the second control signal, shuts down the internal combustion engine 6, and returns to step 2 to continue monitoring the discharge state of the battery pack 1 .

The controller 5 periodically collects the discharge state of the battery pack 1, and determines the change of the internal resistance ΔR by measuring the internal resistance of the battery pack 1 twice adjacently, and the difference between the internal resistance ΔR and the standard internal resistance value R of the battery pack 1 ₀ has a proportional coefficient, if ΔR/R ₀ is greater than the critical coefficient k of the internal resistance increase of the battery pack 1, it means that the battery pack 1 has reached the point of optimal charging efficiency. At this time, the controller 5 needs to turn on the internal combustion engine 6 to make it Drive the generator 3 to charge the battery pack 1;

If ΔR/R ₀ is less than or equal to the internal resistance increase critical coefficient k of the battery pack 1, it means that the battery pack 1 still has enough power to supply the car motor 7, so the internal combustion engine 6 does not work, and the battery pack 1 continues to supply power to the car motor 7 . During the charging process, the controller 3 also detects the output state of the battery pack 1 in real time. When the output voltage reaches the preset maximum output voltage value Vmax of the battery pack 1, it means that the battery pack 1 is fully charged. At this time, the charging should be stopped and the control Device 3 controls internal combustion engine 6 to stop working.

In the implementation process, the delay time T=30s, the value of the critical coefficient k of the internal resistance increase of the battery pack 1 is 5% to 20%, if it is set too small, it may cause misoperation due to measurement errors, set is too large, and charging control cannot be performed in time at the optimal charging point, k is optimally set at 10%, and the highest output voltage value of the battery pack 1 is Vmax=12V.

After the above control, the power supply status of the battery pack is guaranteed, the power supply time of the battery pack is extended, and the driving distance of the hybrid electric vehicle is longer. In terms of the best charging efficiency of the battery pack, it not only makes full use of the energy, but also prolongs the service life of the battery pack, which provides a guarantee for the stability and reliability of the system.

Claims (5)

1. a New-energy electric vehicle automatic charge device, comprises battery pack (1) and controller (5), and described battery pack (1) provides power supply to electric motor of automobile (7) and controller (5), it is characterized in that:

The input of described controller (5) is connected with charging detection module (4), this charging detection module (4) is connected on the output of battery pack (1), the output controlling combustion engine (6) of described controller (5), internal combustion engine (6) drives generator (3) work, and the electric energy of generator (3) output is described battery pack (1) charging after charging circuit (2) is processed;

The control step of described New-energy electric vehicle automatic charge device is:

Step 1, the standard internal resistance value that battery pack (1) is set is R ₀, by controller (5), turning on the power switch, battery pack (1) is electric motor of automobile (7) power supply;

Step 2, charging detection module (4) detects the discharge condition of battery pack (1), the magnitude of voltage that controller (5) obtains voltmeter in charging detection module (4) is that the current value of V, ammeter is that the internal resistance value of I, internal resistance detection instrument is r, and according to the resistance of calculating battery pack (1) is R;

Step 3, delay time T;

Step 4, the magnitude of voltage that controller (5) obtains voltmeter in charging detection module (4) is that the current value of V', ammeter is that the internal resistance value of I', internal resistance detection instrument is r', and according to the resistance of calculating battery pack (1) is R';

Step 5, controller (5) calculates the internal resistance difference DELTA R of battery pack (1) according to Δ R=R'-R;

Step 6, controller (5) judgement Δ R/R ₀whether be greater than k, described k is the internal resistance increment critical coefficient of battery pack (1):

If Δ R/R ₀be greater than k, enter step 7;

If Δ R/R ₀be less than or equal to k, enter step 9;

Step 7, controller (5) output the first control signal, starting apparatus combustion engine (6) work, by internal combustion engine (6), driving generator (3) is battery pack (1) charging;

Step 8, the magnitude of voltage that controller (5) obtains voltmeter in charging detection module (4) is V', judges whether magnitude of voltage V' is less than the maximum output voltage value V of battery pack (1) _max:

If V' is less than V _max, enter step 7 and continue charging;

If V' is more than or equal to V _max, enter step 9;

Step 9, controller (5) output the second control signal, closes internal combustion engine (6), continues the discharge condition of monitoring battery pack (1).

2. a kind of New-energy electric vehicle automatic charge device according to claim 1, it is characterized in that: described charging detection module (4) comprises internal resistance detection instrument, voltmeter and ammeter, internal resistance detection instrument and voltmeter are attempted by the two ends of battery pack (1), and ammeter is serially connected on the output of battery pack (1).

3. a kind of New-energy electric vehicle automatic charge device according to claim 1, is characterized in that: described battery pack (1) is lithium battery group, lead acid accumulator or nickel-hydrogen accumulator.

4. a kind of New-energy electric vehicle automatic charge device according to claim 1, is characterized in that: described internal combustion engine (6) is gasoline engine, diesel engine, natural gas engine or ethanol engine.

5. according to its a kind of New-energy electric vehicle automatic charge device claimed in claim 1, it is characterized in that: described delay time T=30s, the value of the internal resistance increment critical coefficient k of described battery pack (1) is 5%～20%, the maximum output voltage value V of described battery pack (1) _max=12V.