Power battery heating and fast charging device and use control method thereof

Abstract

The application relates to the technical field of power battery heating and fast charging, and discloses a power battery heating and fast charging device, which comprises a pulse generating device, wherein the pulse generating device comprises a direct current input end, a direct current output end, a bridge arm converter, an energy storage inductor and a device controller; the positive pole of the direct current input end is connected with the first end of the bridge arm converter through a mode switching switch, the negative pole is connected with the second end, one end of the positive pole is connected with the energy storage inductor, the other end of the energy storage inductor is connected with the midpoint of the bridge arm converter, the two ends of the bridge arm converter are respectively connected with the positive pole and the negative pole of the direct current output end, and the mode switching switch and the bridge arm converter are connected with the device controller. The application further discloses a use control method of the power battery heating and fast charging device. The power battery heating and fast charging device and the use control method thereof can realize the heating and fast charging of the power battery at the same time under a low-temperature environment, and greatly shorten the overall time required for the fast charging of the electric vehicle.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power battery heating and fast charging, in particular to a power battery heating and fast charging device and a use control method thereof. BACKGROUND

[0002] New energy vehicles are supported by policies due to their low-carbon and environmentally friendly advantages. Lithium-ion power batteries are widely used in the field of new energy vehicles due to their long cycle life, high specific energy and specific power, and low self-discharge rate. However, the internal resistance of the battery increases sharply at low temperatures, and the output power and available energy decrease significantly. In addition, it is difficult to charge the battery at low temperatures, and lithium dendrites are easily generated during charging, which may cause safety hazards. These greatly limit the charging speed of lithium-ion batteries in cold environments, thereby prolonging the charging time of the battery. In contrast to traditional fossil fuel vehicles that only need a few minutes to refuel, new energy electric vehicles usually take half an hour to an hour to charge under fast charging conditions. This disadvantage is further magnified in low-temperature environments, and electric vehicles not only face range anxiety but also face severe charging anxiety. In northern China, the slow charging speed of electric vehicles in winter low-temperature environments has become a major pain point in promoting electric vehicles.

[0003] In a low-temperature environment, the existing charging strategy is to directly replace the battery at a battery replacement station or to additionally add a preheating stage before charging the power battery.

[0004] Replacing the battery at the battery replacement station has many difficulties in actual operation. For example, in the extremely low temperature of winter in the north, the icing of the chassis of the electric vehicle will seriously affect the battery replacement efficiency. The battery must be broken to replace it, thereby prolonging the battery replacement time. In addition, the charging and energy supplementing speed of the battery replacement station will decrease at low temperatures, and the low energy supplementing efficiency will affect the battery replacement experience.

[0005] The additional preheating stage before charging will prolong the overall charging time due to the addition of the preheating working step, and will also seriously affect the charging experience. SUMMARY

[0006] The purpose of the present application is to overcome the above technical deficiencies, and to provide a power battery heating and fast charging device and a use control method thereof, which can realize simultaneous heating and fast charging of the power battery in a low-temperature environment, thereby greatly shortening the overall time required for fast charging of the electric vehicle.

[0007] In order to achieve the above-mentioned purpose, the power battery heating and fast charging device relates to a charging adapter connected with a direct current charging gun of a direct current charging pile and a charging gun connected with a charging port of an electric vehicle, further comprising a pulse generating device, the pulse generating device comprises a direct current input end connected with the charging adapter and a direct current output end connected with the charging gun, the pulse generating device further comprises a bridge arm converter, an energy storage inductor and a device controller, the bridge arm converter comprises a first fully controlled device and a second fully controlled device connected in series, the positive pole of the direct current input end is connected with the first end of the bridge arm converter through a mode switching switch, the negative pole of the direct current input end is connected with the second end of the bridge arm converter, one end of the energy storage inductor is connected with the positive pole of the direct current input end, the other end of the energy storage inductor is connected with the midpoint of the bridge arm converter, the two ends of the bridge arm converter are respectively connected with the positive pole and the negative pole of the direct current output end, the mode switching switch and the bridge arm converter are connected with the device controller, and the device controller is connected with the direct current charging pile and the charging port of the electric vehicle through the charging adapter and the charging gun.

[0008] A use control method of the power battery heating and fast charging device, the device controller obtains the real-time battery temperature of the power battery through the charging port of the electric vehicle, compares the real-time battery temperature with a preset temperature threshold, enters a conventional fast charging mode if the real-time battery temperature is higher than the preset temperature threshold, enters a heating and fast charging mode if the real-time battery temperature is lower than the preset temperature threshold, controls the pulse generating device to generate a high-frequency pulse current to heat and fast charge the power battery until the power battery is heated to the preset temperature threshold and enters the conventional fast charging mode.

[0009] Preferably, after the direct current charging pile, the power battery heating and fast charging device and the charging port of the electric vehicle are connected and confirmed, the device controller simultaneously starts to periodically send a communication handshake message, performs CAN bus low-voltage communication with a vehicle controller of the electric vehicle through the charging port of the electric vehicle, and obtains the real-time battery temperature of the power battery.

[0010] Preferably, when entering the conventional fast charging mode, the device controller controls the mode switching switch in the pulse generating device to be closed, and simultaneously controls the bridge arm converter to be closed.

[0011] Preferably, when entering the heating and fast charging mode, the device controller communicates with the direct current charging pile to make it work in a constant voltage mode, controls the mode switching switch in the pulse generating device to be opened, and controls the bridge arm converter to work, so as to realize high-frequency pulse current charging and heating of the power battery.

[0012] Preferably, when the bridge arm converter is working, the device controller controls the bridge arm converter to enter working mode one first, controls the first controllable device to be open, and controls the second controllable device to be closed, so that the current flows from the positive pole of the DC input end, through the energy storage inductor and the second controllable device, and returns to the negative pole of the DC input end, at this time, the current I L of the energy storage inductor is given a value, and when the current I L of the energy storage inductor rises to I ref + D / 2, the current I ref of the energy storage inductor is given a value, and the device controller controls the bridge arm converter to enter working mode two, controls the first controllable device to be closed, and controls the second controllable device to be open, so that the current flows from the positive pole of the DC input end, through the energy storage inductor, the first controllable device and the DC output end, and returns to the negative pole of the DC input end, at this time, the current I L of the energy storage inductor is given a value, and when the current I L of the energy storage inductor falls to I ref -D / 2, the device controller controls the bridge arm converter to switch to working mode one, and the two working modes of the bridge arm converter are switched repeatedly to generate high-frequency pulse charging current.

[0013] Preferably, when the bridge arm converter is working, the voltage of the DC input end of the pulse generating device is less than the voltage of the DC output end.

[0014] Preferably, the device controller reads the real-time temperature and SOC of the power battery, looks up a table to select the pulse charging current parameter pair (I ref , f ref ) to achieve the maximum heat generation rate without lithium precipitation, I ref is a given value of the inductor current, and f ref is the frequency of the pulse charging current, and the pulse charging current parameter pair is updated in real time according to the changes of the real-time temperature and SOC of the power battery during the charging process, so that the power battery maintains the maximum heat generation rate.

[0015] Preferably, the device controller independently controls the amplitude and frequency of the pulse charging current, and the amplitude and frequency of the pulse charging current are realized by hysteresis control of the current of the energy storage inductor, taking I ref as a given value of the inductor current, and presetting D as a hysteresis width to construct a current hysteresis negative feedback control, increasing the hysteresis width D to reduce the frequency f ref of the pulse charging current, and reducing the hysteresis width D to increase the frequency f ref of the pulse charging current.

[0016] Compared with the prior art, the present application has the following advantages:

[0017] 1. The power battery heating and fast charging device is connected between the direct current charging pile and the electric vehicle as an intermediate device, so that the power battery of the electric vehicle can be heated and fast charged at the same time in a low temperature environment, thereby greatly shortening the overall time required for fast charging of the electric vehicle;

[0018] 2. The heating and fast charging method adopted is high-frequency pulse charging. The internal resistance of the battery under high-frequency pulse is small, causing small polarization voltage, so that charging can be carried out with a large current without lithium precipitation, thereby shortening the overall charging time in a low temperature environment;

[0019] 3. The heating method is internal preheating, which utilizes the internal impedance of the power battery to generate heat. Compared with external heating methods, the thermal-electric conversion efficiency is improved, and the power battery can achieve a faster temperature rise rate;

[0020] 4. The structure is simple and easy to implement. In a low temperature environment, the device only needs to be connected as an intermediate device between the charging pile and the electric vehicle, so that the power battery of the electric vehicle can be heated and fast charged at the same time without changing the existing structure of the direct current charging pile and the electric vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a schematic diagram of the interaction of the power battery heating and fast charging device of the application with the direct current charging pile and the electric vehicle;

[0022] Figure 2 is Figure 1 is a circuit structure schematic diagram of the pulse generating device;

[0023] Figure 3 is an energy flow diagram of the working mode one of the embodiment of the application in the heating and fast charging mode;

[0024] Figure 4 is an energy flow diagram of the working mode two of the embodiment of the application in the heating and fast charging mode;

[0025] Figure 5 is a control flow chart of the application working in the heating and fast charging mode.

[0026] The component labels in the figure are as follows:

[0027] Direct current charging pile 1, direct current charging gun 2, charging adapter 3, electric vehicle 4, charging port 5, charging gun 6, pulse generating device 7, direct current input end 8, direct current output end 9, bridge arm converter 10, device controller 11, power battery 12, power battery heating and fast charging device 13, energy storage inductor L, first full control device Q1, second full control device Q2, mode switching switch S1. DETAILED DESCRIPTION

[0028] The application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] As shown in Figure 1 and Figure 2 , a power battery heating and fast charging device comprises a charging adapter 3 connected with a direct current charging gun 2 of a direct current charging pile 1 and a charging gun 6 connected with a charging port 5 of an electric vehicle 4, and further comprises a pulse generating device 7, the pulse generating device 7 comprises a direct current input end 8 connected with the charging adapter 3 and a direct current output end 9 connected with the charging gun 6, the pulse generating device 7 further comprises a bridge arm converter 10, an energy storage inductor L and a device controller 11, the bridge arm converter 10 comprises a first fully controlled device Q1 and a second fully controlled device Q2 connected in series, a positive pole of the direct current input end 8 is connected with a first end of the bridge arm converter 10 through a mode switching switch S1, a negative pole of the direct current input end 8 is connected with a second end of the bridge arm converter 10, one end of the energy storage inductor L is connected with the positive pole of the direct current input end 8, the other end of the energy storage inductor L is connected with a midpoint of the bridge arm converter 10, two ends of the bridge arm converter 10 are respectively connected with a positive pole and a negative pole of the direct current output end 9, the mode switching switch S1 and the bridge arm converter 10 are both connected with the device controller 11, and the device controller 11 is connected with the direct current charging pile 1 and the electric vehicle 4 through the charging adapter 3 and the charging gun 6 respectively.

[0030] The use control method of the power battery heating and fast charging device in the embodiment, the device controller 11 obtains a real-time battery temperature T of a power battery 12 through the charging port 5 of the electric vehicle 4, compares the real-time battery temperature T with a preset temperature threshold T e , if the real-time battery temperature T is higher than the preset temperature threshold T e , enters a conventional fast charging mode, if the real-time battery temperature T is lower than the preset temperature threshold T e , enters a heating and fast charging mode, the device controller 11 controls the pulse generating device 7 to generate a high-frequency pulse current to heat and fast charge the power battery 12 until the power battery 12 is heated to the preset temperature threshold T e , and enters the conventional fast charging mode.

[0031] Specifically, after the direct current charging pile 1, the power battery heating and fast charging device 13 and the charging port 5 of the electric vehicle 4 are connected and confirmed, they simultaneously start to periodically send a communication handshake message, the device controller 11 performs CAN bus low-voltage communication with a vehicle controller of the electric vehicle 4 through the charging port 5 of the electric vehicle 4 to obtain the real-time battery temperature of the power battery 12.

[0032] When entering the conventional fast charging mode, the device controller 11 controls the mode switching switch S1 in the pulse generating device 7 to be closed and simultaneously controls the bridge arm converter 10 to be turned off.

[0033] When entering the heating fast charging mode, the device controller 7 communicates with the direct current charging pile 1 to make it work in the constant voltage mode, the device controller 7 controls the mode switching switch S1 in the pulse generating device 7 to be disconnected, controls the bridge arm converter 10 to work, and realizes high-frequency pulse current charging and heating for the power battery 12.

[0034] When the bridge arm converter 10 works, as shown in the figure, Figure 3 the device controller 11 controls the bridge arm converter 10 to enter the working mode one first, controls the first full-controlled device Q1 to be disconnected and the second full-controlled device Q2 to be closed, and the current flows from the positive pole of the direct current input end 8, through the energy storage inductor L and the second full-controlled device Q2, and returns to the negative pole of the direct current input end 8, at this time, the current I L of the energy storage inductor L rises, when I L ≥I ref +D / 2, I ref is the inductance current given value of the energy storage inductor L, and D is the ring width, as shown in the figure, Figure 4 the device controller 11 controls the bridge arm converter 10 to enter the working mode two, the device controller 11 controls the first full-controlled device Q1 to be closed and the second full-controlled device Q2 to be disconnected, and the current flows from the positive pole of the direct current input end 8, through the energy storage inductor L, the first full-controlled device Q1 and the direct current output end 9, and returns to the negative pole of the direct current input end 8, at this time, the inductance current I L of the energy storage inductor L falls, when the inductance current I L ≤I ref -D / 2, the device controller 11 controls the bridge arm converter 10 to switch to the working mode one, and the two working modes of the bridge arm converter 10 are repeatedly switched to generate high-frequency pulse charging current.

[0035] In the embodiment, when the bridge arm converter 10 works, the voltage of the direct current input end 8 of the pulse generating device 7 is less than the voltage of the direct current output end 9.

[0036] In addition, in the heating fast charging mode, the maximum heating speed is sought on the premise of not damaging the capacity of the power battery 12, taking not lithium precipitation as the primary condition, the device controller 11 reads the real-time temperature and SOC of the power battery 12, selects the pulse charging current parameter pair I ref , f ref to realize the maximum heat generation rate under not lithium precipitation, I ref is the inductance current given value, f ref is the frequency of the pulse charging current, and the pulse charging current parameter pair is updated in real time according to the changes of the real-time temperature and SOC of the power battery 12 during the charging process, so that the power battery 12 maintains the maximum heat generation rate.

[0037] In the embodiment, the device controller 11 independently controls the amplitude and frequency of the pulse charging current, which is realized by hysteresis control of the current of the energy storage inductor L, to I ref As the inductance current given value, D is preset as the hysteresis width to construct current hysteresis negative feedback control, by increasing the hysteresis width D to reduce the frequency f of the pulse charging current ref , by reducing the hysteresis width D to increase the frequency f of the pulse charging current ref .

[0038] Finally, as Figure 5 shown, a control method of the device controller 11 in the embodiment, after starting, input the preset temperature threshold T e , read the battery real-time temperature T and SOC of the power battery 12, compare the battery real-time temperature T with the preset temperature threshold T e , if T≥T e , end, enter the conventional fast charging mode, if not, select the pulse charging current parameter pair I ref , f ref corresponding to the maximum heat generation rate of the non-lithium precipitation condition of the current battery real-time temperature T and SOC from the table, adjust the hysteresis width D according to f ref , and carry out heating fast charging, then read the battery real-time temperature T and SOC of the power battery 12 in real time, and compare the battery real-time temperature T with the preset temperature threshold T e .

[0039] The power battery heating fast charging device and the use control method thereof, the power battery heating fast charging device as an intermediate device is connected between the direct current charging pile 1 and the electric vehicle 4, which can realize the heating and fast charging of the power battery 12 of the electric vehicle 4 at the same time in a low temperature environment, thereby greatly shortening the overall time required for the electric vehicle 4 to perform fast charging; the heating fast charging method adopted is high-frequency pulse charging, the internal resistance of the battery under high-frequency pulse is small, causing small polarization voltage, so that charging can be carried out with large current under the condition of avoiding lithium precipitation, thereby shortening the overall charging time in a low temperature environment; the heating method is internal preheating, which utilizes the internal impedance heat generation of the power battery 12, compared with external heating method, improves the thermal-electric conversion efficiency, and can make the power battery 12 obtain a faster temperature rising rate; simple structure, easy to realize, in a low temperature environment, only need to connect the device as an intermediate device between the direct current charging pile 1 and the electric vehicle 4, the power battery 12 of the electric vehicle 4 can be heated and fast charged at the same time, without changing the existing structure of the direct current charging pile 1 and the electric vehicle 4.

Claims

1. A power battery heating fast charging device, comprising a charging adapter (3) connected to a DC charging gun (2) of a DC charging pile (1) and a charging gun (6) connected to a charging port (5) of an electric vehicle (4), characterized in that: It also includes a pulse generator (7), which includes a DC input terminal (8) connected to the charging adapter (3) and a DC output terminal (9) connected to the charging gun (6). The pulse generator (7) also includes a bridge arm converter (10), an energy storage inductor (L), and a device controller (11). The bridge arm converter (10) includes a first fully controlled device (Q1) and a second fully controlled device (Q2) connected in series. The positive terminal of the DC input terminal (8) is connected to the first terminal of the bridge arm converter (10) through a mode switching switch (S1), and the negative terminal of the DC input terminal (8) is connected to the first terminal of the charging gun (6). The second end of the bridge arm converter (10) is connected to the positive terminal of the DC input terminal (8), one end of the energy storage inductor (L) is connected to the positive terminal of the DC input terminal (8), the other end of the energy storage inductor (L) is connected to the midpoint of the bridge arm converter (10), the two ends of the bridge arm converter (10) are connected to the positive and negative terminals of the DC output terminal (9) respectively, the mode switching switch (S1) and the bridge arm converter (10) are both connected to the device controller (11), and the device controller (11) is connected to the DC charging pile (1) and the charging port (5) of the electric vehicle (4) respectively through the charging adapter (3) and the charging gun (6).

2. A method for controlling the use of the power battery heating fast charging device as described in claim 1, characterized in that: The device controller (11) obtains the real-time battery temperature of the power battery (12) through the charging port (5) of the electric vehicle (4), compares the real-time battery temperature with the preset temperature threshold, and if the real-time battery temperature is higher than the preset temperature threshold, it enters the normal fast charging mode. If the real-time battery temperature is lower than the preset temperature threshold, it enters the heating fast charging mode. The device controller (11) controls the pulse generator (7) to generate a high-frequency pulse current to heat and fast charge the power battery (12) until the power battery (12) is heated to the preset temperature threshold and then enters the normal fast charging mode. When entering the normal fast charging mode, the device controller (11) controls the mode switching switch (S1) in the pulse generator (7) to close, and at the same time shuts down the bridge arm converter (10); When entering the heating fast charging mode, the device controller (11) communicates with the DC charging pile (1) to make it work in constant voltage mode. The device controller (11) controls the mode switching switch (S1) in the pulse generator (7) to open, and controls the bridge arm converter (10) to work, so as to realize high-frequency pulse current charging and heating of the power battery (12). When the bridge arm converter (10) is working, the device controller (11) controls the bridge arm converter (10) to first enter working mode one, controls the first full control device (Q1) to open, and the second full control device (Q2) to close. The current flows from the positive terminal of the DC input terminal (8) through the energy storage inductor (L) and the second full control device (Q2) and returns to the negative terminal of the DC input terminal (8). At this time, the current I of the energy storage inductor (L) is... L Rise, when I L ≥I ref When +D / 2, I ref Given a set value for the inductor current of the energy storage inductor (L), where D is the ring width, the device controller (11) controls the bridge arm converter (10) to enter working mode two. The device controller (11) controls the first fully controlled device (Q1) to close and the second fully controlled device (Q2) to open. The current flows from the positive terminal of the DC input terminal (8) through the energy storage inductor (L), the first fully controlled device (Q1), and the DC output terminal (9), and returns to the negative terminal of the DC input terminal (8). At this time, the inductor current I of the energy storage inductor (L) is... L The inductor current I decreases. L ≤I ref When -D / 2, the device controller (11) controls the bridge arm converter (10) to switch to working mode one, and so on, repeatedly switching the two working modes of the bridge arm converter (10) to generate a high-frequency pulse charging current.

3. The method for controlling the use of the power battery heating fast charging device as described in claim 2, characterized in that: After the DC charging pile (1), the power battery heating fast charging device (13) and the charging port (5) of the electric vehicle (4) are connected and confirmed, they simultaneously start periodically sending communication handshake messages. The device controller (11) communicates with the vehicle controller of the electric vehicle (4) via the charging port (5) of the electric vehicle (4) through the CAN bus low-voltage communication to obtain the real-time battery temperature of the power battery (12).

4. The method for controlling the use of the power battery heating fast charging device as described in claim 2, characterized in that: When the bridge arm converter (10) is working, the voltage at the DC input terminal (8) of the pulse generator (7) is less than the voltage at the DC output terminal (9).

5. The method for controlling the use of the power battery heating fast charging device as described in claim 2, characterized in that: The device controller (11) reads the real-time temperature and SOC of the power battery (12), and selects the pulse charging current parameter pair (I) from the table. ref f ref To achieve the maximum heat generation rate without lithium plating, I ref Given the inductor current, f ref The frequency of the pulse charging current is set, and the pulse charging current parameter pair is updated in real time according to the real-time temperature and SOC change of the power battery (12) during the charging process, so that the power battery (12) maintains the maximum heat generation rate.

6. The method for controlling the use of the power battery heating fast charging device as described in claim 2, characterized in that: The device controller (11) independently controls the amplitude and frequency of the pulse charging current. The amplitude and frequency of the pulse charging current are achieved by hysteresis control of the current of the energy storage inductor (L), with I... ref As the inductor current setpoint, a preset value D is used to construct the current hysteresis negative feedback control by increasing the loop width D. ref By reducing the ring width D, the frequency f of the pulse charging current can be increased. ref .

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