Battery charging and discharging control circuit, control method and new energy vehicle

Abstract

The present invention relates to the technical field of circuit design, and in particular to a battery charge and discharge control circuit, a control method and a new energy vehicle. The discharge control loop includes a first switch, a second switch, a third switch, a fourth switch and a pre-charge resistor, one end of the first switch is connected to the negative electrode of the battery, the other end is connected to the negative electrode of the discharge load, the positive electrode of the discharge load is connected to one end of the second switch, the other end of the second switch is connected to one end of the third switch, the other end of the third switch is connected to the positive electrode of the battery, one end of the pre-charge resistor is connected to the positive electrode of the battery, the other end is connected to one end of the fourth switch, the other end of the fourth switch is connected to the other end of the second switch, and when discharging, the discharge load is first pre-charged, so that the current in the circuit rises slowly, and when the pre-charge operation is completed, the discharge is performed, so as to avoid the large current generated by directly closing multiple switches from causing damage to each component, so that the components are damaged or the entire circuit is damaged.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit design, and in particular to a battery charging and discharging control circuit, a control method and a new energy vehicle. Background Art

[0002] An important function of the battery management system BMS is to protect the battery. How to protect the battery? A simple and effective way is to eliminate the charge and discharge current of the battery. Therefore, the control of the charge and discharge switch has become a standard feature of the BMS. There are two types of control of the relay by the BMS. One is strong control, that is, absolute control. The BMS is not affected by external devices (mainly the VCU new energy vehicle controller). According to the safety status of the battery, it autonomously controls the on and off of the switch in the circuit. The other is weak control, relative control. The BMS basically has no autonomous control and needs to receive commands sent by the VCU to control the on and off of the switch in the circuit according to the commands. In weak control, after the VCU sends a control command to control the switch, the BMS implements the operation of opening or closing the switch in the circuit according to the real-time command of the VCU. However, VCU is not a professional circuit switch management device, and its requirements for the opening and closing of switches do not take into account the risks that may exist in switches; for example, VCU sends a closure at the same time, and multiple switches in the control circuit are closed at the same time to achieve the purpose of discharge. At this time, if BMS completely follows the VCU command and closes multiple switches at the same time, the conduction will generate a large circuit, which may cause multiple switches to stick together, causing permanent damage to multiple switches, or burn the load, so that the circuit is damaged. Therefore, it can be seen that the existing control circuit still has certain defects. Summary of the invention

[0003] The main technical problem solved by the present invention is that the existing battery charge and discharge control circuit easily causes circuit or switch damage.

[0004] A battery charge and discharge control circuit, comprising a discharge control loop, wherein the discharge control loop comprises a first switch, a second switch, a third switch, a fourth switch and a pre-charge resistor;

[0005] One end of the first switch is connected to the negative electrode of the battery, and the other end is connected to the negative electrode of the discharge load, the positive electrode of the discharge load is connected to one end of the second switch, the other end of the second switch is connected to one end of the third switch, and the other end of the third switch is connected to the positive electrode of the battery, so as to form a discharge circuit;

[0006] One end of the pre-charging resistor is connected to the positive electrode of the battery, and the other end is connected to one end of the fourth switch, and the other end of the fourth switch is connected to the other end of the second switch, thereby forming a discharge pre-charging loop.

[0007] In one embodiment, a fifth switch is further included, one end of the fifth switch is connected to one end of the third switch, the other end is connected to the positive electrode of the charging load, and the negative electrode of the charging load is connected to the other end of the first switch, so as to form a charging control loop;

[0008] The other end of the fourth switch is also connected to one end of the fifth switch to form a pre-charging loop.

[0009] In one embodiment, the first switch, the second switch, the third switch, the fourth switch and the fifth switch are all relays.

[0010] In one embodiment, a battery management system is further included, which is connected to the battery and the control end of the relay, and is used to receive a control signal to control the on and off of the relay, thereby controlling the discharge control circuit or the charging control circuit to conduct and operate.

[0011] In one embodiment, it further includes a host computer and / or a VCU, wherein the host computer and / or the VCU is communicatively connected to the battery management system via a CAN bus and is used to send a control signal to the battery management system.

[0012] A battery charge and discharge control method, including a discharge control method, the discharge control method comprising:

[0013] The battery management system determines in real time whether the first control signal sent by the VCU is received, and if so, controls the second switch to be turned on;

[0014] After the second switch is turned on, the battery management system determines in real time whether it has received the first control signal sent by the VCU, and if so, controls the first switch to be turned on;

[0015] After the first switch is turned on, the battery management system determines in real time whether a fourth control signal sent by the VCU is received, and if so, controls the fourth switch to be turned on to perform a pre-charging operation;

[0016] The battery management system determines in real time whether the pre-charging operation is completed, and if the pre-charging operation is completed and a third control signal is received from the VCU, the battery management system controls the third switch to be turned on for discharging.

[0017] In one embodiment, a charging control method is further included, and the charging control method includes:

[0018] The battery management system determines in real time whether the fifth control signal sent by the VCU is received, and if so, controls the fifth switch to be turned on;

[0019] After the fifth switch is turned on, the battery management system determines in real time whether it has received the second control signal sent by the VCU, and if so, controls the first switch to be turned on;

[0020] After the first switch is turned on, the battery management system determines in real time whether a fourth control signal sent by the VCU is received, and if so, controls the fourth switch to be turned on to perform a pre-charging operation;

[0021] The battery management system determines in real time whether the pre-charging operation is completed, and if the pre-charging operation is completed and a third control signal is received from the VCU, the battery management system controls the third switch to be turned on for charging.

[0022] In one embodiment, it further includes: after the third switch is turned on, the battery management system also determines in real time whether a first disconnection signal sent by the VCU is received, and if so, controls the third switch to be disconnected.

[0023] In one embodiment, the battery management system determines in real time whether the pre-charging operation is completed, including:

[0024] The battery management system obtains the load voltage across the discharge load or the charge load in real time. If the load voltage exceeds eighty percent of the battery voltage, it is determined that the pre-charge operation is completed.

[0025] A new energy vehicle comprises the battery charge and discharge control circuit as described above.

[0026] According to the battery charge and discharge control circuit of the above embodiment, it includes a discharge control loop, which includes a first switch, a second switch, a third switch, a fourth switch and a pre-charge resistor. One end of the first switch is connected to the negative electrode of the battery, and the other end is connected to the negative electrode of the discharge load. The positive electrode of the discharge load is connected to one end of the second switch, and the other end of the second switch is connected to one end of the third switch. The other end of the third switch is connected to the positive electrode of the battery, thereby forming a discharge loop. One end of the pre-charge resistor is connected to the positive electrode of the battery, and the other end is connected to one end of the fourth switch. The other end of the fourth switch is connected to the other end of the second switch, thereby forming a discharge pre-charge loop. In this way, when discharging, the first switch, the second switch and the fourth switch are first controlled to be turned off in sequence, so that the discharge pre-charge loop works, and the discharge load is pre-charged, so that the current in the circuit rises slowly. When the pre-charge operation is completed, the third switch is closed and the fourth switch is opened at the same time to discharge. In this way, the large current generated by directly closing multiple switches is avoided to cause damage to each component, causing damage to the components or the entire circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of a battery charge and discharge control circuit according to an embodiment of the present application;

[0028] Figure 2 This is a schematic diagram of the structure of a battery management control system according to an embodiment of the present application;

[0029] Figure 3 This is a flow chart of the discharge control method according to an embodiment of the present application;

[0030] Figure 4 This is a flow chart of the charging control method according to an embodiment of the present application;

[0031] Figure 5 This is a schematic diagram of the structure of a battery charge and discharge control circuit according to another embodiment of the present application. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0033] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0034] The serial numbers assigned to the components in this article, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning.

[0035] Embodiment 1:

[0036] Please refer to Figure 1 This embodiment provides a battery charge and discharge control circuit, such as Figure 1 , which includes a discharge control loop, and the discharge control loop includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4 and a pre-charge resistor R.

[0037] Among them, one end of the first switch S1 is connected to the negative electrode of the battery U, and the other end is connected to the negative electrode of the discharge load RL. The positive electrode of the discharge load RL is connected to one end of the second switch S2. The other end of the second switch S2 is connected to one end of the third switch S3. The other end of the third switch S3 is connected to the positive electrode of the battery U, thereby forming a discharge circuit, and the battery can discharge the load RL.

[0038] Among them, one end of the pre-charging resistor R is connected to the positive electrode of the battery U, and the other end is connected to one end of the fourth switch S4, and the other end of the fourth switch S4 is connected to the other end of the second switch S2, so as to form a discharge pre-charging circuit. When charging, first close switches S1, S2 and S4 to make the discharge pre-charging circuit conductive, and perform a discharge pre-charging operation, so that the voltage across the discharge load RL increases slowly. When it increases to the preset value of the battery U, close switch S3 and disconnect S4, and the battery U is continuously discharged. This prevents switches S1, S2 and S3 from being closed at the same time, which may cause excessive instantaneous current in the circuit and burn components or load RL.

[0039] Furthermore, the battery charge and discharge control circuit also includes a fifth switch S5, one end of the fifth switch S5 is connected to one end of the third switch S3, and the other end is connected to the positive electrode of the charging load DC, and the negative electrode of the charging load DC is connected to one end of the first switch S1, so as to form a charging control loop to charge the battery U. At the same time, the other end of the fourth switch S4 is also connected to one end of the fifth switch S5, and the battery U, the pre-charging resistor R, S4, S5, DC and S1 form a charging pre-charging loop. When charging, the fifth switch S5, S1 and S4 are closed in sequence to turn on the pre-charging loop and perform the pre-charging operation. When the pre-charging operation is completed, the switch S4 is disconnected and the switch S3 is closed, so that the load DC charges the battery U stably.

[0040] In this embodiment, the first switch, the second switch, the third switch, the fourth switch and the fifth switch are all relays, and the relays can conveniently control on and off.

[0041] Furthermore, the battery charge and discharge control circuit of this embodiment also includes a battery management system BMS, which is used to manage the charge and discharge of the battery U. The battery management system BMS is connected to the battery through a voltage acquisition line. At the same time, the battery management system BM is connected to the control ends of the five relays through control signal lines. The BMS is used to receive control signals to control the on and off of the relays, thereby controlling the discharge control circuit or the charging control circuit to conduct.

[0042] Furthermore, the battery charge and discharge control circuit of this embodiment also includes a host computer and a VCU, which are communicatively connected to the battery management system BMS via a CAN bus, and the host computer and the VCU are used to send control signals to the battery management system BMS to control the battery discharge or charge the battery.

[0043] Embodiment 2

[0044] Based on the battery charge and discharge control circuit provided in the first embodiment, this embodiment provides a battery charge and discharge control method, which includes a discharge control method, such as Figure 3 , the discharge control method comprises:

[0045] Step 201: The battery management system determines in real time whether it has received the first control signal sent by the VCU, and if so, controls the second switch to be turned on;

[0046] Step 202: After the second switch is turned on, the battery management system determines in real time whether it has received the first control signal sent by the VCU, and if so, controls the first switch to be turned on;

[0047] Step 203: After the first switch is turned on, the battery management system determines in real time whether a fourth control signal sent by the VCU is received, and if so, controls the fourth switch to be turned on to perform a pre-charging operation;

[0048] Step 204: The battery management system determines in real time whether the pre-charging operation is completed. If the pre-charging operation is completed and a third control signal is received from the VCU, the third switch is controlled to be turned on for discharging.

[0049] Furthermore, this embodiment also provides a charging control method, such as Figure 4 , the charging control method comprises:

[0050] Step 301: The battery management system determines in real time whether a fifth control signal sent by the VCU is received, and if so, controls the fifth switch to be turned on;

[0051] Step 302: After the fifth switch is turned on, the battery management system determines in real time whether it has received the second control signal sent by the VCU, and if so, controls the first switch to be turned on;

[0052] Step 303: After the first switch is turned on, the battery management system determines in real time whether it has received the fourth control signal sent by the VCU, and if so, controls the fourth switch to be turned on to perform a pre-charging operation;

[0053] Step 304: The battery management system determines in real time whether the pre-charging operation is completed. If the pre-charging operation is completed and a third control signal is received from the VCU, the third switch is controlled to be turned on for charging.

[0054] Furthermore, the charge and discharge control method of this embodiment also includes: after the third switch is turned on, the battery management system also determines in real time whether a first disconnection signal sent by the VCU is received, and if so, controls the third switch to be disconnected.

[0055] Specifically, in this embodiment, the battery management system determines in real time whether the pre-charging operation is completed, including: the battery management system obtains the load voltage across the discharge load or the charging load in real time, and if the load voltage exceeds eighty percent of the battery voltage, it is determined that the pre-charging operation is completed.

[0056] Embodiment 3

[0057] This embodiment provides a battery management and control system for a new energy vehicle, the control system comprising a battery, a charge and discharge control circuit, a battery management system and a VCU.

[0058] Among them, Figure 2 The charge and discharge control circuit is electrically connected to the battery to form a charge control loop and a discharge control loop; the battery management system is connected to the charge and discharge control circuit in communication, and the battery management system is used to receive control signals to control the on and off of the charge control loop and the discharge control loop. The VCU is connected to the battery management system in communication via the CAN bus to send control signals to the battery management system.

[0059] Among them, the discharge control circuit and the charge control circuit are the same as those in the first embodiment, and are not described again here.

[0060] Embodiment 4

[0061] This embodiment provides a new energy vehicle, which is equipped with a battery charge and discharge control circuit as provided in the first embodiment or a battery management and control system as provided in the third embodiment.

[0062] Embodiment 5

[0063] Based on the first embodiment, this embodiment provides a battery charge and discharge control circuit, which includes a discharge control circuit, and the discharge control circuit includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4 and a pre-charge resistor R. In this embodiment, the first switch, the second switch, the third switch, the fourth switch and the fifth switch are all relays, and the relays can conveniently control the conduction and disconnection. Figure 5 The first switch S1 is a total negative relay, the second switch S2 is an electric drive relay, the third switch S3 is a total positive relay, the fourth switch S4 is a pre-charge relay, and the fifth switch S5 is a charging relay.

[0064] In the vehicle-mounted BMS system, the BMS directly controls the battery total positive relay, battery total negative relay, pre-charge relay, electric drive high-voltage relay, and charging relay. The battery total positive relay is connected to the battery high-voltage positive pole; the battery total negative relay is connected to the battery high-voltage negative pole; the pre-charge relay is connected in series with the pre-charge resistor, and then connected in parallel with the battery total positive relay. One end of the electric drive high-voltage relay is connected to the total positive relay, and the other end is connected to the electric drive high-voltage input positive pole; one end of the charging relay is connected to the total positive relay, and the other end is connected to the charging pile output positive pole. The BMS management system software has necessary overcurrent protection measures to prevent excessive current from damaging the relay. The pre-charge resistor R is to prevent the battery from discharging the large load capacitor and causing a short circuit at the moment the relay is turned on. The pre-charge resistor R needs to have a certain overcurrent capacity and heat dissipation capacity.

[0065] This embodiment is aimed at the BMS weak relay control strategy. The control ability of BMS over the relay is greatly reduced, which greatly increases the risk of relay damage. If a series of preset control timings are added to the BMS program to ensure that when the VCU issues a confusing or even wrong command, the BMS will not execute the command by mistake, but will first consider safety and risks. On the basis of ensuring safety, executing the VCU command will make the entire power system safer and more reliable. The control steps of this embodiment are as follows:

[0066] 5-1 Discharge mode:

[0067] Step1. BMS self-test is completed without any faults.

[0068] Step 2. BMS receives VCU command and enters discharge mode according to relevant command.

[0069] Step 3. BMS determines whether VCU has issued a command to close the electric drive high-voltage relay. If there is such a command, the electric drive high-voltage relay is closed, otherwise it continues to wait for the command.

[0070] Step 4. BMS determines whether VCU has issued a command to close the battery main negative relay. If there is such a command, the battery main negative relay is closed, otherwise it continues to wait for the command.

[0071] Step 5. BMS determines whether VCU has issued a command to close the pre-charge relay. If there is such a command, the pre-charge relay is closed, otherwise it continues to wait for the command.

[0072] Step 6. After closing the pre-charge relay, the BMS determines whether the pre-charge is successful. If the pre-charge is successful, the pre-charge success flag is sent to the VCU, and then waits for the VCU to issue a command to close the battery main positive relay. If there is such a command, the battery main positive relay is closed, otherwise continue to wait for the command.

[0073] Step 7. BMS determines whether VCU has issued a command to disconnect the pre-charge relay. If there is such a command, the pre-charge relay will be disconnected, otherwise it will continue to wait for the command.

[0074] Step 8. BMS officially enters discharge mode, and the battery can discharge the external load with high power.

[0075] 5-2 Charging mode:

[0076] Step1. BMS self-test is completed without any faults.

[0077] Step 2. BMS receives VCU commands and enters charging mode according to relevant commands.

[0078] Step 3. BMS determines whether VCU has issued a command to close the charging relay. If there is such a command, the charging relay is closed; otherwise, it continues to wait for the command.

[0079] Step 4. BMS determines whether VCU has issued a command to close the battery main negative relay. If there is such a command, the battery main negative relay is closed, otherwise it continues to wait for the command.

[0080] Step 5. BMS determines whether VCU has issued a command to close the pre-charge relay. If there is such a command, the pre-charge relay is closed, otherwise it continues to wait for the command.

[0081] Step 6. After closing the pre-charge relay, the BMS determines whether the pre-charge is successful. If the pre-charge is successful, the pre-charge success flag is sent to the VCU, and then waits for the VCU to issue a command to close the battery main positive relay. If there is such a command, the battery main positive relay is closed, otherwise continue to wait for the command.

[0082] Step 7. BMS determines whether VCU has issued a command to disconnect the pre-charge relay. If there is such a command, the pre-charge relay will be disconnected, otherwise it will continue to wait for the command.

[0083] Step 8. BMS officially enters charging mode, and the charging pile can charge the battery at high power.

[0084] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the concept of the present invention, some simple deductions, modifications or substitutions can be made.

Claims

1. A battery charge and discharge control method, applied to a battery charge and discharge control circuit, characterized in that: The battery charge and discharge control circuit is characterized by comprising a discharge control loop, wherein the discharge control loop comprises a first switch, a second switch, a third switch, a fourth switch and a pre-charge resistor; One end of the first switch is connected to the negative electrode of the battery, and the other end is connected to the negative electrode of the discharge load, the positive electrode of the discharge load is connected to one end of the second switch, the other end of the second switch is connected to one end of the third switch, and the other end of the third switch is connected to the positive electrode of the battery, so as to form a discharge circuit; One end of the pre-charging resistor is connected to the positive electrode of the battery, and the other end is connected to one end of the fourth switch, and the other end of the fourth switch is connected to the other end of the second switch, so as to form a discharge pre-charging loop; The battery charge and discharge control circuit further includes a fifth switch, one end of the fifth switch is connected to one end of the third switch, the other end is connected to the positive electrode of the charging load, and the negative electrode of the charging load is connected to the other end of the first switch, thereby forming a charging control loop; The other end of the fourth switch is also connected to one end of the fifth switch, thereby forming a charging pre-charging loop; The battery charge and discharge control method includes a discharge control method and a charge control method, and the discharge control method includes: The battery management system determines in real time whether the first control signal sent by the VCU is received, and if so, controls the second switch to be turned on; After the second switch is turned on, the battery management system determines in real time whether it has received the first control signal sent by the VCU, and if so, controls the first switch to be turned on; After the first switch is turned on, the battery management system determines in real time whether a fourth control signal sent by the VCU is received, and if so, controls the fourth switch to be turned on to perform a pre-charging operation; The battery management system determines in real time whether the pre-charging operation is completed, and if the pre-charging operation is completed and receives a third control signal sent by the VCU, controls the third switch to be turned on for discharging; The charging control method comprises: The battery management system determines in real time whether the fifth control signal sent by the VCU is received, and if so, controls the fifth switch to be turned on; After the fifth switch is turned on, the battery management system determines in real time whether it has received the second control signal sent by the VCU, and if so, controls the first switch to be turned on; After the first switch is turned on, the battery management system determines in real time whether a fourth control signal sent by the VCU is received, and if so, controls the fourth switch to be turned on to perform a pre-charging operation; The battery management system determines in real time whether the pre-charging operation is completed, and if the pre-charging operation is completed and a third control signal is received from the VCU, the battery management system controls the third switch to be turned on for charging.

2. The battery charge and discharge control method according to claim 1, characterized in that: Also includes: After the third switch is turned on, the battery management system further determines in real time whether a first disconnection signal sent by the VCU is received, and if so, controls the third switch to be disconnected.

3. The battery charge and discharge control method according to claim 1, characterized in that: The battery management system determines in real time whether the pre-charging operation is completed, including: The battery management system obtains the load voltage across the discharge load or the charge load in real time. If the load voltage exceeds eighty percent of the battery voltage, it is determined that the pre-charge operation is completed.

4. The battery charge and discharge control method according to claim 1, characterized in that: The first switch, the second switch, the third switch, the fourth switch and the fifth switch are all relays.

5. The battery charge and discharge control method according to claim 4, characterized in that: It also includes a battery management system, which is connected to the battery and the control end of the relay and is used to receive a control signal to control the on and off of the relay, thereby controlling the discharge control circuit or the charging control circuit to conduct and work.

6. The battery charge and discharge control method according to claim 5, characterized in that: It also includes a host computer and / or a VCU, which is communicatively connected to the battery management system via a CAN bus and is used to send a control signal to the battery management system.

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