Disclosure of Invention
Based on this, it is necessary to provide an electric vehicle driving system, a driving circuit and an electric vehicle battery heating method for solving the problems of low heating power and low heating efficiency of the conventional battery pack.
A driving circuit, comprising:
a power supply unit including a first battery pack and a second battery pack; and
the inverter circuit comprises a first bridge arm, a second bridge arm and a third bridge arm;
the first electrode of the first battery pack is connected with the upper bridge arm of the first bridge arm through a first bus, and the first electrode of the second battery pack is connected with the upper bridge arm of the second bridge arm and the upper bridge arm of the third bridge arm through a second bus respectively;
the second electrode of the first battery and the second electrode of the second battery are collinear to form a first end;
the lower bridge arm of the first bridge arm, the lower bridge arm of the second bridge arm and the lower bridge arm of the third bridge arm are collinear to form a second end;
the first end is connected with the second end bus.
An electric vehicle drive system, comprising:
the drive circuit of any one of the above embodiments;
a battery management circuit electrically connected with the driving circuit;
the first controller is electrically connected with the driving circuit; and
and the second detection circuit is electrically connected with the first controller.
An electric automobile battery heating method is realized by adopting an electric automobile driving system;
the electric automobile driving system comprises a driving circuit, a battery management circuit electrically connected with the driving circuit and a first controller electrically connected with the driving circuit;
the driving circuit comprises a power supply unit and an inverter circuit which are connected through a bus, wherein the power supply unit comprises a first battery pack and a second battery pack; the inverter circuit comprises three bridge arms; the first electrode of the first battery pack is connected with the upper bridge arm of one bridge arm of the three bridge arms through a first bus, and the first electrode of the second battery pack is connected with the upper bridge arm of the rest two bridge arms of the three bridge arms through a second bus;
the second electrode of the first battery pack and the second electrode of the second battery pack are collinear and then connected with the lower bridge arm bus of the three bridge arms;
the electric automobile battery heating method comprises the following steps:
s10, before the electric automobile is started, judging whether the electric automobile needs to be heated by a battery through the battery management circuit;
s20, after the electric automobile is confirmed to be required to be heated, controlling the inverter circuit through the first controller so as to charge the first battery pack to the second battery pack;
s30, after the charging time of the first battery pack to the second battery pack reaches a first time threshold, the inverter circuit is controlled by the first controller so that the second battery pack charges the first battery pack, and the power supply unit is polarized in the charging and discharging process, so that the controllable temperature rise of each battery pack in the power supply unit is realized.
The application provides an electric automobile driving system, a driving circuit and an electric automobile battery heating method. The electric vehicle driving system comprises a first controller, a power supply unit and an inverter circuit. The power supply unit includes two battery packs. When the electric automobile battery is heated, one ends of the two battery packs are mutually independent, and the other ends of the two battery packs are collinear. Lower bridge arms of three bridge arms in the inverter circuit are collinear. And an upper bridge arm of one bridge arm of three bridge arms in the inverter circuit is connected with an independent bus at one end of a battery pack. And the upper bridge arms of the remaining two bridge arms in the three bridge arms in the inverter circuit are connected with the independent bus at one end of the other battery pack. The first controller is electrically connected with the inverter circuit. According to the electric automobile battery heating method, the first controller is used for controlling the opening and closing of the three bridge arms of the inverter circuit so as to finish energy output and energy recovery of the power supply unit, and further the power supply unit is polarized, so that the battery of the power supply unit is heated controllably. The maximum working current of the power switching device in the inverter circuit is higher, and the electric vehicle battery heating method can realize high-power heating on the basis of not adding other devices by utilizing the electric vehicle driving system, so that the heating efficiency is effectively improved.
Detailed Description
In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is, however, susceptible of embodiment in many other ways than those herein described and similar modifications can be made by those skilled in the art without departing from the spirit of the application, and therefore the application is not limited to the specific embodiments disclosed below.
It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, one embodiment of the present application provides a driving circuit 100. The driving circuit 100 includes a power supply unit 10 and an inverter circuit 20.
The power supply unit 10 includes a first battery pack 11 and a second battery pack 12. The inverter circuit 20 includes a first leg 21, a second leg 22, and a third leg 23. The first electrode of the first battery pack 11 is connected to an upper arm bus bar of the first arm 21. The first electrode of the second battery pack 12 is connected to the upper arm bus bar of the second arm 22 and the upper arm bus bar of the third arm 23, respectively. The second electrode of the first battery 11 and the second electrode of the second battery 12 are collinear to form a first end 101. The lower leg of the first leg 21, the lower leg of the second leg 22, and the lower leg of the third leg 23 are collinear to form a second end 201. The first end 101 is bus-connected to the second end 201. The first battery pack 11 has an equivalent resistance R1. The second battery 12 has an equivalent resistance R2.
The first electrode may be a positive electrode of a battery. The first electrode may also be the negative electrode of the battery. The second electrode may be a positive electrode of a battery. The second electrode may also be the negative electrode of the battery. When the positive electrode of the first battery 11 and the positive electrode of the second battery 12 are the first electrodes. Only one end of the three legs of the inverter 20 are connected in parallel to the same potential point. Two of the three bridge arms are connected in parallel to the same potential point at the other end. The other end of the rest one of the three bridge arms is independently connected to the other potential point.
In this embodiment, the power supply unit 10 includes two battery packs. The inverter circuit 20 includes three legs. One end of the first battery pack 11 is connected to an upper arm of the first arm 21 through a first bus. One end of the second battery pack 12 is connected to the upper arm of the second arm 22 and the upper arm of the third arm 23 through a second bus bar, respectively. The other end of one battery is collinear with the other end of the other battery. The lower bridge arms of the three bridge arms are collinear. The collinear lower bridge arm is connected with one collinear end of the battery pack. The two battery packs are independent of each other, so that the driving circuit 100 has more degrees of freedom. The driving circuit 100 can realize a heating function and a parking equalization function of a battery without adding other devices. The driving circuit 100 includes two battery packs, and compared with the conventional three battery pack power supply mode, the power supply implementation in this embodiment reduces one battery pack, so that one voltage sampling circuit can be reduced, and thus the cost of the battery management system can be reduced to a certain extent.
Referring to fig. 2, in one embodiment, the driving circuit 100 further includes a status switch 140. The status switch 140 is disposed between the first bus bar and the second bus bar. The driving circuit 100 may be provided as an electric car driving circuit. When the electric vehicle is in a driving state, the state change switch 140 is closed. When the electric vehicle is in a low-temperature heating state, the state change switch 140 is turned off.
In this embodiment, when the electric vehicle is in different states, the relationship between the power supply unit 10 and the inverter circuit 20 can be effectively changed by the state change switch 140. When the electric vehicle is in a driving state, the state change switch 140 is closed. At this time, the upper arms of the three arms of the inverter circuit 20 are collinear. The lower bridge arms of the three bridge arms of the inverter circuit 20 are collinear. At this time, the driving of the electric vehicle can be achieved by controlling the inverter circuit 20 through a conventional vector, and the cost of controlling the inverter circuit 20 is reduced. When the electric vehicle is in a low-temperature heating state and the battery pack in the power supply unit 10 needs to be heated, the state change switch 140 is turned off. At this time, only one end of the three legs of the inverter 20 are connected in parallel to the same potential point. Two of the three bridge arms are connected in parallel to the same potential point at the other end. The other end of the rest one of the three bridge arms is independently connected to the other potential point. The two battery packs are mutually independent, so that the driving circuit has more degrees of freedom. The driving circuit 100 can realize a heating function of the battery without adding other devices.
In one embodiment, each battery pack in the power supply unit 10 includes one battery cell 110 and one first bypass switch 120.
One of the battery cells 110 and one of the first bypass switches 120 are connected in series. The power supply unit 10 includes a plurality of battery cells 111 therein. The model number, nominal capacity of the plurality of cells 111 may be the same. The plurality of cells 111 may be equally divided into three groups. The plurality of cells 111 in each group are connected to each other to form one battery cell 110. The connection mode of the electric cells 111 in one of the battery units 110 is the same as the connection mode of the electric cells 111 in the other two battery units 110. The connection mode is one of a plurality of battery cells 111 being connected in series, a plurality of battery cells 111 being connected in parallel and then being connected in series, a plurality of battery cells 111 being connected in parallel or a plurality of battery cells 111 being connected in series and then being connected in parallel.
The first bypass switch 120 may be a relay. The first bypass switch 120 may also be a switch circuit in which a relay is connected in parallel with a series-connected precharge relay and a precharge group. The first bypass switch 120 is one of an electromagnetic relay, an insulated gate bipolar transistor, or a metal-oxide semiconductor field effect transistor.
In this embodiment, each battery pack is connected to a first bypass switch 120, so that individual control of each battery pack can be achieved. Isolation of the failed battery from the normal battery can be achieved by opening the first bypass switch 120 connected to the failed battery when one of the batteries fails
In one embodiment, the driving circuit 100 further includes a second bypass switch 130.
The second bypass switch 130 is electrically connected between the first end 101 and the second end 201. The second bypass switch 130 may be a relay. The second bypass switch 130 may also be a switch circuit in which a relay is connected in parallel with a series-connected precharge relay and a precharge group. The second bypass switch 130 is one of an electromagnetic relay, an insulated gate bipolar transistor, or a metal-oxide semiconductor field effect transistor. By opening the second bypass switch 130, the purpose of opening the power supply unit 10 and the inverter circuit 20 can be achieved.
In one embodiment, each bridge arm of the inverter circuit 20 includes two power switching devices 211 connected in series.
The collector terminal of one power switch 211 of the two power switch devices 211 connected in series is connected with the positive bus of one battery pack. The emitter terminal of the other power switching device 211 of the two power switching devices 211 connected in series is connected to the negative bus bar of one battery pack. One power switching device 211 of each bridge arm may form an upper bridge arm of one bridge arm. The other power switching device 211 of each bridge arm may form the lower bridge arm of one bridge arm. The bridge arm may be an insulated gate bipolar transistor. The three-phase output terminals of the inverter circuit 20 are respectively connected with a three-phase bus W, U, V of the three-phase motor 30. The three-phase motor 30 may be a three-phase synchronous motor. The three-phase motor 30 may also be a three-phase asynchronous motor. The inverter circuit 20 can output frequencies up to several hundred and thousand weeks, and can drive motors with various rotational speeds in the driving circuit 100.
Referring to fig. 3, an embodiment of the present application provides an electric vehicle driving system 200. The electric vehicle driving system 200 includes a driving circuit 100, a battery management circuit 40, a first controller 50, and a second detection circuit 60.
The battery management circuit 40 is electrically connected to the driving circuit 100. The first controller 50 is electrically connected to the driving circuit 100. The second detection circuit 60 is electrically connected to the first controller 50. The driving circuit 100 in this embodiment is similar to the driving method of the driving circuit 100 in the above embodiment, and will not be described here again. The battery management circuit 40 is configured to detect a state of charge of the power supply unit 10 and an operation state of the power supply unit 10. The battery management circuit 40 is also used to regulate the power supply unit 10. For example, the battery management circuit 40 may control the opening and closing of the first bypass switch 120 and the second bypass switch 130 in the power supply unit 10. The first controller 50 is configured to control the inverter circuit 20 to fix the combination of on-power switching devices 211. The battery management circuit 40 is connected with the first controller 50 through an isolation signal circuit. The second detection circuit 60 is configured to detect an induced current of the three-phase motor 30. The second detection circuit 60 is further configured to report the magnitude information of the induced current to the first controller 50. The first controller 50 may control the inverter circuit 20 according to the amplitude information.
In this embodiment, the electric vehicle driving system 200 includes a driving circuit 100, a battery management circuit 40, and a first controller 50. The power supply unit 10 in the driving circuit 100 includes two battery packs. The inverter circuit 20 includes three legs. One end of the first battery pack 11 is connected to an upper arm of the first arm 21 through a first bus. One end of the second battery pack 12 is connected to the upper arm of the second arm 22 and the upper arm of the third arm 23 through a second bus bar, respectively. The other end of one battery is collinear with the other end of the other battery. The lower bridge arms of the three bridge arms are collinear. The collinear lower bridge arm is connected with one collinear end of the battery pack. The two battery packs are independent of each other, so that the driving circuit 100 has more degrees of freedom. The electric vehicle driving system 200 can realize the driving function, the heating function and the parking balancing function of the electric vehicle battery on the basis of not adding other devices.
Referring to fig. 4, in one embodiment, the electric vehicle has a control center. The battery management circuit 40 includes a first detection circuit 41 and a second controller 42.
The first detection circuit 41 includes a voltage detection unit 411, a current detection unit 412, and a temperature detection unit 413, and the voltage detection unit 411, the current detection unit 412, and the temperature detection unit 413 are electrically connected to the power supply unit 10, respectively. The second controller 42 is electrically connected to the power supply unit 10.
The first detection circuit 41 reports the detected voltage, current and temperature signals to a control center of the electric vehicle. The control center controls driving, braking, heating and parking balance of the driving circuit 100 through the first controller 50 and the second controller 42 according to the received signals. The battery management circuit 40 can quickly and efficiently detect the performance parameters of the two battery packs in the power supply unit 10 through the first detection circuit 41 and the second controller 42.
Referring to fig. 5, an embodiment of the present application provides a method for heating a battery of an electric vehicle. The electric vehicle driving system 200 is adopted to realize the electric vehicle battery heating method. The electric automobile battery heating method comprises the following steps:
and S10, before the electric automobile is started, judging whether the electric automobile needs to be heated by a battery through the battery management circuit 40. In step S10, it may be determined whether the electric vehicle is in a low-temperature heating state by detecting the temperature of the battery cell.
S20, when it is confirmed that the electric vehicle needs to be heated, the inverter circuit 20 is controlled by the first controller 50 so that the first battery pack 11 charges the second battery pack 12. In step S20, by controlling the switching states of the three arms of the inverter circuit 20, the first battery pack 11 may charge the three-phase motor 30 first, and then the first battery pack 11 and the three-phase motor 30 together charge the second battery pack 12. In this process, except for the necessary power consumption, the first battery pack 11 is integrally represented as charging the second battery pack 12.
S30, after the charging time of the first battery pack 11 to the second battery pack 12 reaches the first time threshold, the inverter circuit 20 is controlled by the first controller 50 to charge the second battery pack 12 to the first battery pack 11, and the power supply unit 10 polarizes itself during the charging and discharging process, so as to realize the controllable temperature rise of each battery pack in the power supply unit 10.
In step S30, by controlling the switching states of the three arms of the inverter circuit 20, a process may be implemented in which the second battery pack 12 charges the three-phase motor 30 first, and then the electric second battery pack 12 charges the first battery pack 11 together with the three-phase motor 30. In this process, except for the necessary power consumption, the second battery pack 12 is integrally represented as charging the first battery pack 11.
In this embodiment, the first controller 50 controls the opening and closing of the three bridge arms of the inverter circuit 20 to complete the energy output and energy recovery of the power supply unit 10, so that the power supply unit 10 itself is polarized, thereby realizing the controllable temperature rise of the battery of the power supply unit 10. The maximum operating current of the power switching device 211 in the inverter circuit 20 and the maximum operating current of the three-phase motor 30 are high. The electric automobile battery heating method can realize high-power heating and effectively improve heating efficiency. The power switch device 211 is used as a control element, and the three-phase motor 30 is used as an energy storage element. And a special heating element is not required to be added in the heating process of the battery, so that the cost of the power system of the electric automobile is reduced. The electric automobile battery heating method heats the battery packs and realizes electric quantity balance among the battery packs.
Referring to fig. 6, in one embodiment, the driving circuit 100 further includes a three-phase motor 30, and each phase bus of the three-phase motor 30 is connected to an output end of one of the bridge arms; the three-phase motor 30 is electrically connected to the second detection circuit 60. The first leg 21 is provided as a first working leg. One of the second leg 22 and the third leg 23 is set as a second working leg. The other of the second leg 22 and the third leg 23 remains in an open state. In an alternative embodiment, the selection of the second working bridge arm is determined according to the rotor position of the motor, and the bridge arm connected to the ac busbar close to the rotor orientation position is selected as the second working bridge arm. In the process of heating the battery pack, the movement amplitude of the motor rotor is smaller, so that the possibility of movement of the wheels during parking heating is reduced.
The step of controlling the inverter circuit 20 by the first controller 50 to charge the first battery pack 11 to the second battery pack 12 after confirming that the electric vehicle needs to be heated in S20 includes:
and S21, controlling the upper bridge arm of the first working bridge arm and the lower bridge arm of the second working bridge arm to be conducted through the first controller 50 so as to charge the first battery pack 11 to the three-phase motor 30.
In step S21, the forward current of the three-phase motor 30 increases, and as shown in fig. 8, the current may rise from position 0 to position 1. The current change process in step S21 satisfies the following formula:
wherein E is 1 Open circuit voltage for the first sub-stack. R is R 1 Is the internal resistance of the first battery pack. L is the working inductance of the driving motor in the heating process, R L Is the loop resistance during heating.
S22, detecting, by the second detecting circuit 60, whether the current amplitude in the three-phase motor 30 is greater than or equal to a target heating current upper threshold. In step S22, the target heating current upper threshold may be determined according to the performance of the battery and the current-withstanding capability of the power switch assembly 211 in the inverter circuit 20.
And S23, when the current amplitude in the three-phase motor 30 is greater than or equal to the upper threshold value of the target heating current, the first controller 50 controls the lower bridge arm of the second working bridge arm to be disconnected, and controls the upper bridge arm of the second working bridge arm to be conducted, so that the first battery pack 11 and the three-phase motor 30 charge the second battery pack 12.
In step S23, the first battery pack 11 and the three-phase motor 30 are discharged, and the second battery pack 12 is charged. The forward current of the three-phase motor 30 is reduced. As shown in fig. 8, the current drops from position 1 to position 2. The current change process in step S23 satisfies the following formula:
wherein E is 2 Open circuit voltage for the second sub-stack. R is R 2 Is the internal resistance of the second battery pack.
The step S23 of controlling, by the first controller 50, the lower leg of the second working leg to be disconnected and controlling the upper leg of the second working leg to be conducted when the current amplitude in the three-phase motor 30 is greater than or equal to the target heating current upper threshold value, so that the step of charging the first battery pack 11 and the three-phase motor 30 to the second battery pack 12 includes:
whether the current amplitude in the three-phase motor 30 is less than or equal to a target heating current flowing down threshold value is detected by the second detection circuit 60. And when the current amplitude in the three-phase motor 30 is less than or equal to the target heating current threshold, repeating the steps S21-S23 until the charging time of the first battery pack 11 to the second battery pack 12 reaches a first time threshold. As shown in fig. 8, the current runs from position 3 to position 3 T+ 。
In this embodiment, by controlling the switching states of the three arms of the inverter circuit 20, the first battery pack 11 firstly charges the three-phase motor 30, and secondly, the first battery pack 11 and the three-phase motor 30 together charge the second battery pack 12. In this process, the method achieves the purpose of charging the first battery pack 11 to the second battery pack 12, except for the necessary power consumption.
Referring to fig. 7, in one embodiment, after the charging time of the first battery pack 11 to the second battery pack 12 reaches the first time threshold, the step of controlling, by the first controller 50, the inverter circuit 20 to charge the second battery pack 12 to the first battery pack 11, and the power supply unit 10 polarizes itself during the charging and discharging process, so as to implement the controllable temperature rise of each battery pack in the power supply unit 10 includes:
and S31, controlling the conduction of the lower bridge arm of the first working bridge arm and the upper bridge arm of the second working bridge arm through the first controller 50 so as to charge the second battery pack 12 to the three-phase motor 30.
In step S31, the forward current of the three-phase motor 30Falling to zero and continuing to rise after a negative current is established. As shown in fig. 8, the current can flow from position 3 T+ Run to position 4. The current change process in step S31 satisfies the following formula:
wherein E is 1 Open circuit voltage for the first sub-stack. R is R 1 Is the internal resistance of the first battery pack. L is the working inductance of the driving motor in the heating process, R L Is the loop resistance during heating.
S32, detecting, by the second detection circuit 60, whether the current amplitude in the three-phase motor 30 is equal to or greater than a target heating current upper threshold. In step S32, the target heating current upper threshold may be determined according to the performance of the battery and the current-withstanding capability of the power switch assembly 211 in the inverter circuit 20.
And S33, when the current amplitude in the three-phase motor 30 is greater than or equal to the upper threshold value of the target heating current, the first controller 50 controls the lower bridge arm of the first working bridge arm to be disconnected, and controls the upper bridge arm of the first working bridge arm to be conducted, so that the second battery pack 12 and the three-phase motor 30 charge the first battery pack 11.
In step S33, the second battery pack 12 and the three-phase motor 30 are discharged, and the first battery pack 11 is charged. The negative current of the three-phase motor 30 decreases. As shown in fig. 8, the current runs from position 4 to position 5. The current change process in step S33 satisfies the following formula:
wherein E is 2 Open circuit voltage for the second sub-stack. R is R 2 Is the internal resistance of the second battery pack.
The step S33, when the current amplitude in the three-phase motor 30 is greater than or equal to the target heating current upper threshold, controls the lower bridge arm of the first working bridge arm to be disconnected and controls the upper bridge arm of the first working bridge arm to be conducted by the first controller 50, so that the step of charging the second battery pack 12 and the three-phase motor 30 to the first battery pack 11 includes:
whether the current amplitude in the three-phase motor 30 is less than or equal to a target heating current flowing down threshold value is detected by the second detection circuit 60. And when the current amplitude in the three-phase motor 30 is less than or equal to the target heating current threshold, repeating the steps S31-S33 until the charging time of the second battery pack 12 to the first battery pack 11 reaches a second time threshold.
When the current amplitude in the three-phase motor 30 is less than or equal to the target heating current threshold, repeating steps S31-S33 until the charging time of the second battery pack 12 to the first battery pack 11 reaches the second time threshold, further comprising:
whether the cell temperature of the power supply unit 10 is less than a driving threshold temperature is detected by the battery management circuit 40. And when the temperature of the battery cell is smaller than the driving threshold temperature, repeating the steps S10-S30 until the temperature of the battery cell is larger than or equal to the driving threshold temperature or a heating stop instruction is received.
In this embodiment, by controlling the switching states of the three arms of the inverter circuit 20, it is possible to realize that the second battery pack 12 charges the three-phase motor 30 first. Next, the second battery pack 12 and the three-phase motor 30 together charge the first battery pack 11. In this process, the method achieves the purpose of charging the second battery pack 12 to the first battery pack 11, except for the necessary power consumption.
In one embodiment, the step of determining, by the battery management circuit 40, whether the electric vehicle needs to be heated by the battery before the electric vehicle starts S10 includes:
whether the cell temperature of the power supply unit 10 is less than a driving threshold temperature is detected by the battery management circuit 40. And when the temperature of the battery cell is smaller than the driving threshold temperature, confirming that the electric automobile needs to be heated by a battery. And when the temperature of the battery cell is greater than or equal to the driving threshold temperature, the electric automobile is started normally.
In this embodiment, by detecting the relationship between the temperature of the battery cell and the driving threshold temperature, it may be determined whether the electric vehicle needs to perform low-temperature electric heating.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the claims. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.