CN113370845B - Current commutation control device and method of BMS active equalization system and automobile - Google Patents

Current commutation control device and method of BMS active equalization system and automobile Download PDF

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Publication number
CN113370845B
CN113370845B CN202110633158.2A CN202110633158A CN113370845B CN 113370845 B CN113370845 B CN 113370845B CN 202110633158 A CN202110633158 A CN 202110633158A CN 113370845 B CN113370845 B CN 113370845B
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China
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single battery
winding
output end
transformer
current
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CN202110633158.2A
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CN113370845A (en
Inventor
周海莹
刘敏通
冷正明
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Gree Electric Appliances Inc of Zhuhai
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Gree Electric Appliances Inc of Zhuhai
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/18—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries of two or more battery modules
    • B60L58/22—Balancing the charge of battery modules
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
    • H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
    • H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/79—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/797—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J2207/20—Charging or discharging characterised by the power electronics converter
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/72—Electric energy management in electromobility

Abstract

The invention discloses a current commutation control device and method of a BMS active equalization system and an automobile, wherein the device comprises the following components: a detection unit configured to detect a current direction of the unit cell; and the control unit is configured to control the working state of the switching tube in the DC/DC converter according to the current direction of the single battery so as to enable the working state of the switching tube in the DC/DC converter to be adjusted along with the current direction of the single battery. According to the scheme, the consistency of the current direction and the controlled switch of the BMS in the active balancing process is controlled, so that active balancing failure caused by inconsistent current direction and the controlled switch can be avoided, and the reliability of the active balancing of the BMS is improved.

Description

Current commutation control device and method of BMS active equalization system and automobile
Technical Field
The invention belongs to the technical field of automobiles, and particularly relates to a current reversing control device and method of a BMS active balancing system and an automobile, and particularly relates to a BMS active balancing current reversing detection device and method and an automobile.
Background
With the exhaustion of global petroleum resources, the development of electric vehicles has been a major trend. As a battery management system (Battery Management System, abbreviated as BMS) which is one of three key technologies of the electric automobile, corresponding technology transformation is also performed, and the performance of the battery management system is important to improve the utilization rate of the battery, prolong the service life of the battery and ensure the safe trip of the electric automobile.
When the consistency of the battery pack is not good, unreliable problems such as spontaneous combustion of the electric automobile can be caused, so that the balancing technology of the BMS becomes the important research direction of the BMS. In the process of active equalization, the BMS has the problem of current commutation, and if the current direction is inconsistent with a controlled switch, the active equalization can fail, and the power supply safety of the battery pack is affected.
The foregoing is provided merely for the purpose of facilitating understanding of the technical solutions of the present invention and is not intended to represent an admission that the foregoing is prior art.
Disclosure of Invention
The invention aims to provide a current commutation control device, a current commutation control method and an automobile of a BMS active balancing system, which are used for solving the problems that if the current direction is inconsistent with a controlled switch in the active balancing process of the BMS, the active balancing is failed and the reliability of the BMS active balancing is affected, and achieving the effects that the current direction and the consistency of the controlled switch in the active balancing process of the BMS are controlled, the active balancing failure caused by the inconsistent current direction and the controlled switch can be avoided, and the reliability of the BMS active balancing is improved.
The invention provides a current commutation control device of a BMS active equalization system, which comprises: a single battery and a DC/DC converter; the DC/DC converter is arranged on the output side of the single battery; the current commutation control device of the BMS active equalization system comprises: a detection unit and a control unit; wherein the detection unit is configured to detect a current direction of the single battery; the control unit is configured to control the working state of the switching tube in the DC/DC converter according to the current direction of the single battery, so that the working state of the switching tube in the DC/DC converter is adjusted along with the current direction of the single battery.
In some embodiments, the DC/DC converter comprises: a transformer; the first output end of the single battery is connected to the first connection end of the primary winding of the transformer; the second output end of the single battery is connected to the second connecting end of the primary winding of the transformer; one output end is positive and the other output end is negative in the first output end of the single battery and the second output end of the single battery; the detection unit detects the current direction of the single battery, and comprises: determining the current direction of the single battery under the condition that the voltage of the first output end of the single battery is higher than the voltage of the second output end of the single battery, wherein the current direction is the direction from the first output end of the single battery to the second output end of the single battery and is recorded as a first direction; and under the condition that the voltage of the first output end of the single battery is lower than the voltage of the second output end of the single battery, determining the current direction of the single battery, namely the direction from the second output end of the single battery to the first output end of the single battery, and recording the direction as a second direction.
In some embodiments, the detection unit comprises: the device comprises an optocoupler module, a first current limiting module and a second current limiting module; the first output end of the single battery is connected to the anode of the diode side in the optocoupler module after passing through the first current limiting module; the second output end of the single battery is connected to the cathode of the diode side in the optocoupler module; the collector electrode at the transistor side in the optocoupler module is connected with a direct current power supply after passing through the second current limiting module; the detection unit determines a current direction of the unit cell, which is a direction from the first output end of the unit cell to the second output end of the unit cell, as a first direction, under a condition that a voltage of the first output end of the unit cell is higher than a voltage of the second output end of the unit cell, and includes: the optocoupler module is configured to output a low level from a collector electrode at a transistor side in the optocoupler module under the condition that the voltage of a first output end of the single battery is higher than the voltage of a second output end of the single battery, so as to determine the current direction of the single battery, wherein the current direction is the direction from the first output end of the single battery to the second output end of the single battery and is recorded as a first direction; the detection unit determines a current direction of the unit cell, which is a direction from the second output end of the unit cell to the first output end of the unit cell, as a second direction, under the condition that a voltage of the first output end of the unit cell is lower than a voltage of the second output end of the unit cell, and includes: the optocoupler module is further configured to output a high level from a collector electrode at a transistor side in the optocoupler module to determine a current direction of the unit cell, which is a direction from the second output end of the unit cell to the first output end of the unit cell, as a second direction, under a condition that a voltage of the first output end of the unit cell is lower than a voltage of the second output end of the unit cell.
In some embodiments, the detection unit further comprises: a filtering module; the filter module is arranged between the collector electrode of the transistor side in the optocoupler module and the ground.
In some embodiments, the secondary winding of the transformer has a center tap, the winding between the first connection end of the secondary winding of the transformer and the center tap is a first winding, and the winding between the second connection end of the secondary winding of the transformer and the center tap is a second winding; the control unit controls the working state of a switching tube in the DC/DC converter according to the current direction of the single battery, and comprises the following components: when the current direction of the single battery is the first direction, controlling a switching tube in the DC/DC converter so as to enable a first winding of a secondary winding of the transformer to work and enable a second winding of the secondary winding of the transformer to not work; and under the condition that the current direction of the single battery is the second direction, controlling a switching tube in the DC/DC converter so as to enable the first winding of the secondary winding of the transformer to be not operated and enable the second winding of the secondary winding of the transformer to be operated.
In some embodiments, the DC/DC converter further comprises: a primary side current direction control module and a secondary side current direction control module; the primary side current direction control module is arranged in a loop where a primary side winding of the transformer is located; the secondary side current direction control module comprises: the first secondary side control module and the second secondary side control module; the first secondary side control module is arranged in a loop where a first winding of a secondary side winding of the transformer is located; the second secondary side control module is arranged in a loop where a second winding of the secondary side winding of the transformer is located; the primary side current direction control module, the first secondary side control module and the second secondary side control module are all provided with switching tube modules; the control unit controls a switching tube in the DC/DC converter to make a first winding of a secondary winding of the transformer work and make a second winding of the secondary winding of the transformer not work when a current direction of the single battery is a first direction, and the control unit comprises: when the current direction of the single battery is the first direction, controlling a switching tube in the primary side current direction control module to be switched on, and controlling a switching tube in the first secondary side control module to be switched on and controlling a switching tube in the second secondary side control module to be switched off, so that a first winding of a secondary side winding of the transformer works and a second winding of the secondary side winding of the transformer does not work; the control unit, when the current direction of the single battery is the second direction, controls the switching tube in the DC/DC converter to make the first winding of the secondary winding of the transformer not work and make the second winding of the secondary winding of the transformer work, including: and under the condition that the current direction of the single battery is the second direction, controlling a switching tube in the primary side current direction control module to be switched on, and controlling a switching tube in the first secondary side control module to be switched off and controlling a switching tube in the second secondary side control module to be switched on, so that a first winding of a secondary side winding of the transformer is not operated, and a second winding of the secondary side winding of the transformer is operated.
In accordance with another aspect of the present invention, there is provided an automobile comprising: the current commutation control device of the BMS active equalization system.
In accordance with the foregoing automobiles, according to still another aspect of the present invention, there is provided a current commutation control method of a BMS active balancing system, the BMS active balancing system comprising: a single battery and a DC/DC converter; the DC/DC converter is arranged on the output side of the single battery; the current commutation control method of the BMS active equalization system comprises the following steps: detecting the current direction of the single battery through a detection unit; and controlling the working state of the switching tube in the DC/DC converter according to the current direction of the single battery through the control unit so as to enable the working state of the switching tube in the DC/DC converter to be adjusted along with the current direction of the single battery.
In some embodiments, the DC/DC converter comprises: a transformer; the first output end of the single battery is connected to the first connection end of the primary winding of the transformer; the second output end of the single battery is connected to the second connecting end of the primary winding of the transformer; one output end is positive and the other output end is negative in the first output end of the single battery and the second output end of the single battery; detecting, by a detection unit, a current direction of the unit cell, including: determining the current direction of the single battery under the condition that the voltage of the first output end of the single battery is higher than the voltage of the second output end of the single battery, wherein the current direction is the direction from the first output end of the single battery to the second output end of the single battery and is recorded as a first direction; and under the condition that the voltage of the first output end of the single battery is lower than the voltage of the second output end of the single battery, determining the current direction of the single battery, namely the direction from the second output end of the single battery to the first output end of the single battery, and recording the direction as a second direction.
In some embodiments, the secondary winding of the transformer has a center tap, the winding between the first connection end of the secondary winding of the transformer and the center tap is a first winding, and the winding between the second connection end of the secondary winding of the transformer and the center tap is a second winding; and a control unit for controlling the working state of a switching tube in the DC/DC converter according to the current direction of the single battery, comprising: when the current direction of the single battery is the first direction, controlling a switching tube in the DC/DC converter so as to enable a first winding of a secondary winding of the transformer to work and enable a second winding of the secondary winding of the transformer to not work; and under the condition that the current direction of the single battery is the second direction, controlling a switching tube in the DC/DC converter so as to enable the first winding of the secondary winding of the transformer to be not operated and enable the second winding of the secondary winding of the transformer to be operated.
Therefore, according to the scheme of the invention, the correctness of the control of the switching tube is determined by detecting and analyzing the current direction in the BMS active balancing process, so that the consistency of the current direction and the controlled switch in the BMS active balancing process is controlled; therefore, the consistency of the current direction of the BMS in the active balancing process and the controlled switch is controlled, active balancing failure caused by inconsistent current direction and the controlled switch can be avoided, and the reliability of the active balancing of the BMS is improved.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
Fig. 1 is a schematic structural view of an embodiment of a current commutation control device of a BMS active balancing system according to the present invention;
FIG. 2 is a schematic diagram of an embodiment of an active equalization circuit;
FIG. 3 is a schematic diagram of an embodiment of a primary current sampling circuit;
FIG. 4 is a schematic diagram of an embodiment of a filter capacitor bank;
FIG. 5 is a schematic diagram of an embodiment of a secondary current direction control circuit;
FIG. 6 is a schematic diagram illustrating an embodiment of an equalization current direction detection circuit;
FIG. 7 is a schematic diagram of an embodiment of a primary current direction control circuit;
fig. 8 is a flowchart illustrating an embodiment of a current commutation control method of the BMS active balancing system according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments of the present invention and corresponding drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The equalization modes adopted in the related schemes are as follows: one is passive equalization: the resistor energy consumption type is that each single battery is connected with a resistor in parallel to split, and the energy consumption balance is to consume redundant energy in a plurality of single batteries, so that the balance of the voltage of the whole battery is realized, namely, redundant electric quantity is directly discharged by the resistor.
The other is active equalization: the energy transfer type energy storage device is characterized in that the energy transfer type energy storage device transfers high monomer energy to low monomer energy or supplements the whole group of energy to the lowest monomer battery, and an energy storage link is needed in the implementation process, so that the energy is better distributed again through the link, namely, the mutual transfer of the energy among the batteries is mainly finished through the switch control of a power tube.
In the process of active balancing, the BMS has the problem of current commutation, and if the current direction is inconsistent with a controlled switch, the BMS can fail to actively balance, and the reliability of the BMS active balancing is affected. If the current direction is inconsistent with the controlled switch, the active equalization will fail, and a short circuit may occur, which affects the life safety of the driver and the passengers.
According to an embodiment of the present invention, there is provided a current commutation control device of a BMS active balancing system. Referring to fig. 1, a schematic diagram of an embodiment of the apparatus of the present invention is shown. The BMS active equalization system includes: a single battery and a DC/DC converter. The DC/DC converter is arranged on the output side of the single battery. The number of the single batteries is more than one, and under the condition that the number of the single batteries is more than two, the single batteries are arranged in series-parallel to form a battery pack.
The current commutation control device of the BMS active equalization system comprises: a detection unit and a control unit. The detection unit is arranged at the output end of the single battery, in particular between the first output end of the single battery and the second output end of the single battery. A detection unit such as a current direction detection circuit. A control unit, such as a Master Chip (MCU) of the BMS active balancing system.
Wherein the detection unit is configured to detect a current direction of the single battery.
The control unit is configured to control the working state of the switching tube in the DC/DC converter according to the current direction of the single battery, so that the working state of the switching tube in the DC/DC converter is adjusted along with the current direction of the single battery, and the current direction of the single battery is matched with or consistent with the working state of the switching tube in the DC/DC converter. The working state of a switching tube in the DC/DC converter comprises the following steps: an off state or an on state.
Therefore, the scheme of the invention provides the BMS active balancing current commutation detection method, and the accuracy of the control of the switching tube is determined by detecting and analyzing the current direction in the BMS active balancing process, so that the reliability of active balancing is achieved.
In some embodiments, the DC/DC converter comprises: a transformer, such as transformer T1. The transformer has a primary winding and a secondary winding.
The output end of the single battery is provided with a first output end and a second output end. The first output end of the single battery is connected to the first connection end of the primary winding of the transformer. And the second output end of the single battery is connected to the second connection end of the primary winding of the transformer. One output end is positive and the other output end is negative in the first output end of the single battery and the second output end of the single battery. For example: as shown in fig. 2, when the unit cell is discharged, the current flows from bat+ through C6C7C8, T1, back to BAT-, where the bat+ voltage is higher than the BAT-voltage. When the single battery is charged, the current flows out from BAT-through T1 and flows back to BAT+, and the voltage of BAT-is higher than BAT+.
The detection unit detects the current direction of the single battery and comprises any one of the following detection conditions:
first detection scenario: and under the condition that the voltage of the first output end of the single battery is higher than the voltage of the second output end of the single battery, determining the current direction of the single battery, and recording the current direction from the first output end of the single battery to the second output end of the single battery as a first direction.
Second detection scenario: and under the condition that the voltage of the first output end of the single battery is lower than the voltage of the second output end of the single battery, determining the current direction of the single battery, namely the direction from the second output end of the single battery to the first output end of the single battery, and recording the direction as a second direction.
Fig. 2 is a schematic diagram of an embodiment of an active equalization circuit. The active equalization circuit shown in fig. 2 can be categorized as a constant current controlled DC/DC (i.e., direct current/direct current) converter with bi-directional energy flow. In the constant current control DC/DC converter, a flyback power supply structure is adopted in a main power topology. That is, the main power part of the constant current control DC/DC converter adopts a flyback DC/DC converter topology structure.
In the example shown in fig. 2, the net marks bat+, BAT-represent positive and negative voltages on the cell side, that is, the cell voltage in the new energy automobile, the magnitude of which is determined by the battery type and is not greater than 5V, typically about 3.3V. 24V, GND is a 24V battery side, namely a low-voltage power supply side in a new energy automobile, and the general values are 12V and 24V. Because of the active equalization process, that is, the charge and discharge process between the single cells, the voltage at the single cell side varies positive and negative (i.e., the voltage difference between bat+ and BAT-may be positive and negative).
As shown in fig. 2, in the constant current control DC/DC converter, on the primary side of the transformer T1:
referring to the example shown in fig. 2, a resistor R1 is connected in parallel to the positive voltage output terminal of the unit cell and the negative voltage output terminal of the unit cell. The resistor R1 is used as a dissipation resistor for dissipating energy of the cell-side capacitors (e.g., the capacitor C6, the capacitor C7, and the capacitor C8). The positive voltage BAT+ of the single battery is connected to the first end of the primary winding of the transformer T1 after passing through the primary current sampling circuit.
Fig. 3 is a schematic diagram of a primary current sampling circuit according to an embodiment. As shown in fig. 3, in the primary current sampling circuit, the ip+ terminal of the hall current sensor U2 is connected to the output terminal of the positive voltage bat+ of the unit cell, and the IP-terminal of the hall current sensor U2 is connected to the first terminal of the primary winding of the transformer T1. The Vcc end of the Hall current sensor U2 is connected with a power supply Vcc1 and is grounded through a capacitor C2. The Uo end of the hall current sensor U2 outputs the primary current i_yuanbian of the transformer T1 through the resistor R4, and is grounded through the capacitor C5 after passing through the resistor R4. The FLT end (such as the filter end of the Hall sensor) of the Hall current sensor U2 is grounded after passing through the capacitor C4. The ground end GND end of the Hall current sensor U2 is grounded.
In the example shown in fig. 3, since the whole DC/DC converter adopts a constant current control mode, that is, the current value of charging and discharging the battery cell (i.e., the unit battery) is used as a control quantity, the current value of charging and discharging the battery cell is collected by using a hall current sensor U2, the hall current sensor U2 can collect positive and negative currents, for example, the ip+ end of the hall current sensor U2 is connected to the output end of the positive voltage bat+ of the unit battery cell, and the IP-end of the hall current sensor U2 is connected to the first end of the primary winding of the transformer T1. The capacitor C4 is used to zero. The resistor R4 and the capacitor C5 form an RC filter, and the common end of the resistor R4 and the capacitor C5 is the output end of the primary side current I_yuanbian of the transformer T1. Because the supply voltage of the hall current sensor U2 is 5V, and the supply voltage of the main chip (e.g., MCU) is 3.3V, the collected current signal (i.e., the primary current i_yuanbian of the transformer T1) needs to be subjected to voltage stabilizing treatment, for example, a voltage stabilizing module (e.g., a voltage stabilizing diode D2) may be disposed at the output end of the primary current i_yuanbian of the transformer T1, and the output voltage of the primary current i_yuanbian of the transformer T1 is ensured not to exceed 3.3V through the voltage stabilizing diode D2.
In another embodiment of the primary current sampling circuit, as shown by the secondary current sampling resistor module of the transformer T1 (e.g. using the resistors R21 and R22 to sample the secondary current of the transformer T1), when sampling the primary current of the transformer T1, the primary current sampling resistor module may be used to sample, e.g. the primary current sampling resistor module is disposed between the output terminal of the positive voltage bat+ of the battery cell and the first terminal of the primary winding of the transformer T1. It should be noted that, because there are two possibilities of positive and negative current, positive and negative processing needs to be performed on the signals sampled by the resistors in the primary current sampling resistor module, for example, the sampled signals are all raised by a set amplitude, so that negative values can also become positive values, and negative values can be forbidden to be transmitted to the main chip (such as the MCU) to destroy the main chip. The secondary side current of the sampling transformer T1 can be used for monitoring the BMS active equalization system and participating in calculation together with detection parameters of the whole BMS active equalization system, and the on/off of the MOS tube is determined according to the calculation result.
Referring to the example shown in fig. 2, a filter capacitor bank is provided on the primary side of the transformer T1. The filter capacitor bank includes: capacitor C6, capacitor C7, and capacitor C8. After being connected in parallel, the capacitor C6, the capacitor C7 and the capacitor C8 are connected between the common end of the primary side current sampling circuit and the transformer T1 and between the negative electrode BAT-of the battery and the common end of the primary side current direction control circuit. Fig. 4 is a schematic structural diagram of an embodiment of a filter capacitor bank. As shown in fig. 4, the filter capacitor group formed by parallel connection of the capacitor C6, the capacitor C7 and the capacitor C8 is mainly used for filtering and energy storage effects of the primary side (input) of the transformer T1 and the secondary side (output) of the transformer T1.
Referring to the example shown in fig. 2, the negative voltage BAT-of the unit cell is connected to the second end of the primary winding of the transformer T1 after passing through the primary current direction control circuit. Fig. 7 is a schematic diagram of a primary current direction control circuit according to an embodiment. As shown in fig. 7, in the primary current direction control circuit, the output terminal of the negative voltage BAT-of the unit cell is connected to the second terminal of the primary winding of the transformer T1 via the resistor R7 and the capacitor C9. The output end of the negative voltage BAT-of the single battery is also connected to the drain electrode of the MOS tube Q1. The source of the MOS transistor Q1 is connected to the source of the MOS transistor Q2. The drain electrode of the MOS tube Q2 is connected to the second end of the primary winding of the transformer T1. The grid electrode of the MOS tube Q1 is connected to the anode of the diode D1, is connected to the cathode of the diode D1 after passing through the resistor R5, is connected to the grid electrode of the MOS tube Q2, and is also connected to the source electrode of the MOS tube Q2 after passing through the resistor R6. The cathode of the diode D1 is used as the input terminal of the driving signal DRIVER0, and the driving signal DRIVER0 can be controlled by the main chip or the current direction detection circuit. Since the primary winding of the transformer T1 is a single winding, the balancing is performed only on the required path in order to ensure the reliability of active balancing, and therefore, the battery to be balanced is required to be gated by the primary current direction control circuit.
In the example shown in fig. 7, the MOS transistors Q1 and Q2 are connected back to back, and the drive signal DRIVER0 is used to control on and off simultaneously. The resistor R5 is a driving resistor and is the same as the damping of the configuration driving circuit. The resistor R6 is used for preventing the mis-conduction and accelerating the discharge of charges between the GS of the MOS tube (namely between the grid electrode and the source electrode of the MOS tube), and the diode D1 plays a role in accelerating the turn-off of the MOS tube. Wherein configuring damping of the drive circuit comprises: at the moment when the MOS tube is turned on, the current can rise rapidly and exceed the rated value, and then when the MOS tube is lowered, the damping is configured to reduce the peak value of the current which is stamped up, so that the MOS tube is not damaged; at the moment the MOS transistor is turned off, the voltage is also the same.
In some embodiments, the detection unit comprises: the device comprises an optocoupler module, a first current limiting module and a second current limiting module. An optocoupler module, such as optocoupler U1. A first current limiting module, such as resistor R2. A second current limiting module, such as resistor R3.
The first output end of the single battery is connected to the anode of the diode side in the optocoupler module after passing through the first current limiting module. And the second output end of the single battery is connected to the cathode of the diode side in the optocoupler module. And the collector electrode at the transistor side in the optocoupler module is connected with a direct-current power supply, such as a direct-current power supply Vcc, after passing through the second current limiting module. And an emitter electrode at the transistor side in the optocoupler module is grounded.
The detection unit determines a current direction of the unit cell, which is a direction from the first output end of the unit cell to the second output end of the unit cell, as a first direction, under a condition that a voltage of the first output end of the unit cell is higher than a voltage of the second output end of the unit cell, and includes:
the optocoupler module is configured to output a low level from a collector electrode at a transistor side in the optocoupler module under a condition that a voltage of a first output end of the single battery is higher than a voltage of a second output end of the single battery, so as to determine a current direction of the single battery, wherein the current direction is a direction from the first output end of the single battery to the second output end of the single battery and is recorded as a first direction.
The detection unit determines a current direction of the unit cell, which is a direction from the second output end of the unit cell to the first output end of the unit cell, as a second direction, under the condition that a voltage of the first output end of the unit cell is lower than a voltage of the second output end of the unit cell, and includes:
the optocoupler module is further configured to output a high level from a collector electrode at a transistor side in the optocoupler module to determine a current direction of the unit cell, which is a direction from the second output end of the unit cell to the first output end of the unit cell, as a second direction, under a condition that a voltage of the first output end of the unit cell is lower than a voltage of the second output end of the unit cell.
That is, the optocoupler module may output a determination result of the current direction of the unit cell from the collector electrode of the transistor side in the optocoupler module according to the voltage difference between the voltage of the first output terminal of the unit cell and the voltage of the second output terminal of the unit cell. The determination result of the current direction of the single battery comprises the following steps: and under the condition that the voltage of the first output end of the single battery is higher than the voltage of the second output end of the single battery, the current direction of the single battery is the direction from the first output end of the single battery to the second output end of the single battery and is recorded as a first direction. And under the condition that the voltage of the first output end of the single battery is lower than the voltage of the second output end of the single battery, the current direction of the single battery is the direction from the second output end of the single battery to the first output end of the single battery and is recorded as a second direction.
Referring to the example shown in fig. 2, a current direction detection circuit is provided on the primary side of the transformer T1. The current direction detection circuit is connected in parallel with the resistor R1. Fig. 6 is a schematic diagram of an embodiment of an equalization current direction detection circuit. As shown in fig. 6, in the balanced current direction detection circuit, the anode on the diode side of the optocoupler U1 is connected to bat+ via a resistor R2. The cathode of the diode side of the optocoupler U1 is connected with BAT-. The collector of the transistor side of the optocoupler U1 is connected with a direct current power supply Vcc through a resistor R3, and the capacitor C1 is grounded, and a voltage V1 is output as an input signal of a driving signal DRIVER 0. The emitter of the transistor side of the optocoupler U1 is grounded.
In the example shown in fig. 6, the optocoupler U1 is used to determine whether the voltage difference at the side of the die exists, the resistor R3 and the resistor R2 are used as current limiting resistors, the current values of the primary side and the secondary side of the optocoupler U1 are configured, and the capacitor C1 is used as a filter capacitor. The two-way diode side of the optocoupler U1 is the primary side of the optocoupler U1, and the transistor side of the optocoupler U1 is the secondary side of the optocoupler U1.
When the optocoupler U1 is in operation, when the upper end of the optocoupler U1 is connected with BAT +, the lower end of the optocoupler U1 is connected with BAT +, that is, when the negative voltage BAT +, of the battery cell is lower than the positive voltage BAT +, of the battery cell, the photodiode in the optocoupler U1 (i.e., the diode side of the optocoupler U1) is turned on, and the triode in the optocoupler U1 (i.e., the transistor side of the optocoupler U1) is also turned on, and at this time, the output voltage V1 of the optocoupler U1 is at a low level.
When the upper end of the optocoupler U1 is connected with BAT-, the lower end is connected with bat+, that is, when the positive voltage bat+ of the single battery is lower than the negative voltage BAT-of the single battery compared with the negative voltage BAT-of the single battery, the photodiode in the optocoupler U1 (i.e. the diode side of the optocoupler U1) is not turned on, so that the triode in the optocoupler U1 (i.e. the transistor side of the optocoupler U1) is turned off, and the output voltage V1 of the optocoupler U1 is at a high level. That is, V1 is different due to the difference in voltage BAT+ and BAT-. When BAT+ is high and BAT-is low, the diode is turned on to emit light, the triode is turned on, and V1 is pulled to ground and low level. BAT+ is low, when BAT-is high, the diode is not conductive, the triode is not conductive, and V1 is pulled to VCC, high level.
Thus, by detecting the level, the actual direction of the balanced current can be obtained.
In some embodiments, the detection unit further comprises: a filter module, such as a capacitor C1. The filter module is arranged between the collector electrode of the transistor side in the optocoupler module and the ground.
In some embodiments, the secondary winding of the transformer has a center tap, the winding between the first connection end of the secondary winding of the transformer and the center tap is a first winding, and the winding between the second connection end of the secondary winding of the transformer and the center tap is a second winding.
As shown in fig. 2, in the constant current control DC/DC converter, on the secondary side of the transformer T1:
referring to the example shown in fig. 2, the secondary winding of the transformer T1 is a winding with a center tap. The first end of the secondary winding of the transformer T1 is connected to the anode of the diode D4, is connected to the first common end of the resistor R21 and the resistor R22 after passing through the resistor R23 and the capacitor C23, and is also connected to the drain electrode of the MOS tube Q3. The output end of the primary side current sampling circuit is used as the primary side current output end of the transformer T1, and the sampled primary side current I_yuanbian of the transformer T1 can be output to a main chip (such as an MCU).
The control unit is used for controlling the working state of a switching tube in the DC/DC converter according to the current direction of the single battery, and comprises any one of the following control situations:
first control scenario: the control unit is specifically further configured to control a switching tube in the DC/DC converter to make the first winding of the secondary winding of the transformer work and make the second winding of the secondary winding of the transformer not work when the current direction of the single battery is the first direction.
Second control scenario: the control unit is specifically further configured to control a switching tube in the DC/DC converter to make the first winding of the secondary winding of the transformer not work and make the second winding of the secondary winding of the transformer work when the current direction of the single battery is in the second direction.
Therefore, the scheme of the invention realizes the real-time detection of the current direction during the active equalization of the BMS, carries out logic judgment in cooperation with the detection of the current sensor, executes a correct equalization strategy, can reduce the unsafe hidden trouble caused by inconsistent high-voltage single batteries of the new energy automobile, effectively realizes the equalization of the high-voltage single batteries of the new energy automobile, increases the reliability of the active equalization of the BMS, and prolongs the service life of the battery pack. Meanwhile, by adding the balanced current direction detection circuit, the balanced reliability of the battery is improved, and the safety of the new energy automobile is improved.
In some embodiments, the DC/DC converter further comprises: a primary side current direction control module and a secondary side current direction control module. A primary current direction control module, such as a primary current direction control circuit. Secondary side current direction control modules, such as secondary side current direction control circuits.
The primary side current direction control module, such as a control circuit where the MOS tube Q1 and the MOS tube Q2 are located, is arranged in a loop where a primary side winding of the transformer is located, namely in a loop formed by the single battery and the primary side winding of the transformer. The secondary side current direction control module comprises: the device comprises a first secondary side control module and a second secondary side control module. The first secondary side control module, such as a control circuit where the MOS transistor Q3 is, is arranged in a loop where a first winding of the secondary side winding of the transformer is. The second secondary control module, such as a control circuit where the MOS transistor Q4 is located, is arranged in a loop where a second winding of the secondary winding of the transformer is located. The primary side current direction control module, the first secondary side control module and the second secondary side control module are all provided with switching tube modules.
The control unit controls a switching tube in the DC/DC converter to make a first winding of a secondary winding of the transformer work and make a second winding of the secondary winding of the transformer not work when a current direction of the single battery is a first direction, and the control unit comprises: the control unit is specifically configured to control the switching tube in the primary side current direction control module to be turned on and the switching tube in the first secondary side control module to be turned on and the switching tube in the second secondary side control module to be turned off under the condition that the current direction of the single battery is in the first direction, so that the first winding of the secondary side winding of the transformer works and the second winding of the secondary side winding of the transformer does not work.
The control unit, when the current direction of the single battery is the second direction, controls the switching tube in the DC/DC converter to make the first winding of the secondary winding of the transformer not work and make the second winding of the secondary winding of the transformer work, including: the control unit is specifically configured to control the switching tube in the primary side current direction control module to be turned on and the switching tube in the first secondary side control module to be turned off and the switching tube in the second secondary side control module to be turned on under the condition that the current direction of the single battery is in the second direction, so that the first winding of the secondary side winding of the transformer is not operated, and the second winding of the secondary side winding of the transformer is operated.
That is, the control unit, which controls the switching tube in the DC/DC converter, includes: the control unit is specifically configured to control the on or off of the switching tube in the primary side current direction control module and/or the secondary side current direction control module, so that the first winding of the secondary side winding of the transformer works and the second winding of the secondary side winding of the transformer does not work under the condition that the current direction of the single battery is in the first direction. And under the condition that the current direction of the single battery is the second direction, the first winding of the secondary winding of the transformer is not operated, and the second winding of the secondary winding of the transformer is operated.
Fig. 5 is a schematic diagram of a secondary current direction control circuit according to an embodiment. As shown in fig. 5, the secondary current direction control circuit controls the mutual conduction between the MOS transistor Q3 and the MOS transistor Q4 to realize the principle that the cell voltage is changed but the direction of the battery 24V is unchanged. When the battery is discharged, the MOS transistor Q4 is closed, so that the battery forms a loop to charge the battery. When the battery is charged, the MOS tube Q3 and 24V are closed to charge the single battery.
The source electrode of the MOS tube Q3 is connected to the first common end of the resistor R1 and the resistor R22, and is also connected to the cathode of the diode D2 after passing through the resistor R24 and the resistor R25, wherein the cathode of the diode D2 is the driving signal DRIVER1. The grid electrode of the MOS tube Q3 is connected to the common end of the resistor R24 and the resistor R25 and is also connected to the anode of the diode D2. Resistor R21 and resistor R22 are connected in parallel, and the first common end of resistor R21 and resistor R22 is the secondary side current I_fubian of transformer T1. The second common ground GND of the resistor R21 and the resistor R22, the capacitor C21, the capacitor C22 and the capacitor C27 are connected in parallel between the output terminal of the second terminal (i.e., the center tap terminal) of the secondary winding of the transformer T1 and the ground GND. The cathode of the diode D4 is connected to the cathode of the diode D5 via the resistor R30 and the resistor R31, and is also connected to the cathode of the diode D5 via the capacitor C25 and the capacitor C26. The second end (i.e., the center tap end) of the secondary winding of the transformer T1 outputs 24V voltage via the common end of the resistor R30 and the resistor R31 and the common end of the capacitor C25 and the capacitor C26.
The third end of the secondary winding of the transformer T1 is connected to the anode of the diode D5, connected to the first common end of the resistor R21 and the resistor R22 after passing through the resistor R26 and the capacitor C24, and also connected to the drain electrode of the MOS tube Q4. The source electrode of the MOS tube Q4 is connected to the first common end of the resistor R21 and the resistor R22 of the transformer T1, and is also connected to the cathode of the diode D3 after passing through the resistor R27 and the resistor R28, wherein the cathode of the diode D3 is the driving signal DRIVER2. The grid electrode of the MOS tube Q4 is connected to the common end of the resistor R27 and the resistor R28 and is also connected to the anode of the diode D3. The first common terminal of the resistor R21 and the resistor R22 is capable of outputting the secondary side current i_fuse of the transformer T1.
Referring to the example shown in fig. 7, the MOS transistors Q1 and Q2 on the single cell side are connected back to back, that is, the sources, i.e., the S poles, of the two tubes are connected together, the gates, i.e., the G poles, of the two tubes are connected together, and the two MOS transistors are driven simultaneously by using the same driving signal DRIVER0 to adapt to the positive and negative changes of the voltage. Also, because the voltage direction of the battery core side can change, the 24V power supply side needs to adopt two windings (namely an upper winding and a lower winding of a secondary winding of the transformer T1) to ensure that the voltage at two ends of the 24V storage battery is always positive. On the secondary side of the transformer T1, two ends of the MOS tube are connected in parallel with RC filter circuits for absorbing turn-off voltage peaks. The drive signal DRIVER1 and the drive signal DRIVER2 are in particular output by the main chip. On the secondary side of the transformer T1, the driving circuits of the MOS transistors Q3 and Q4 are the same as the driving circuits of the MOS transistors Q1 and Q2. Referring to the example shown in fig. 7, the driving circuits of the MOS transistors Q1 and Q2 include: resistor R5, resistor R6, and diode D1. The diode D1 is designed to reduce the turn-off time, the resistor R5 is a driving resistor, and is selected according to the requirement, so as to mainly affect the turn-on time of the MOS transistor, and the resistor R6 is mainly used for protection, so as to prevent misleading of the MOS due to the miller effect.
Thus, when the voltage difference between the cell voltages BAT+, BAT-is positive, the upper winding of the secondary winding of the transformer T1 is operated, and the lower winding is not operated. When the voltage difference between the cell voltages BAT+ and BAT-is negative, the lower winding and the upper winding of the secondary winding of the transformer T1 are not operated. The energy conversion work is completed through the control of the power device. The winding between the first end and the second end of the secondary winding of the transformer T1 is an upper winding. The winding between the second end and the third end of the secondary winding of the transformer T1 is a lower winding.
It should be noted that, when in use, the values of the components mentioned in fig. 2 to 7 can be selected according to the actual situation. For example: specific parameters of the resistors and the capacitors, such as specific values and numbers of the resistors and the capacitors, mentioned in fig. 2 to 7, can be matched according to actual requirements. For example: in the sub-block shown in fig. 2, the RC filtering may take values according to the MCU's different requirements for the signal, for example, F28335 is used, and the values are selected to be 2K and 0.1UF. In fig. 7, matching is required according to the found MOS to eliminate the fluctuation due to the MOS switch.
Through a large number of experimental verification, the technical scheme of the invention is adopted, and the accuracy of the control of the switching tube is determined by detecting and analyzing the current direction in the BMS active balancing process, so as to control the consistency of the current direction and the controlled switch in the BMS active balancing process. Therefore, the consistency of the current direction of the BMS in the active balancing process and the controlled switch is controlled, active balancing failure caused by inconsistent current direction and the controlled switch can be avoided, and the reliability of the active balancing of the BMS is improved.
There is also provided, in accordance with an embodiment of the present invention, an automobile corresponding to the current commutation control device of the BMS active balancing system. The automobile may include: the current commutation control device of the BMS active equalization system.
Since the processes and functions implemented by the automobile of the present embodiment basically correspond to the embodiments, principles and examples of the foregoing apparatus, the description of the present embodiment is not exhaustive, and reference may be made to the related descriptions of the foregoing embodiments, which are not repeated herein.
Through a large number of experimental verification, the technical scheme of the invention is adopted, the accuracy of the control of the switching tube is determined by detecting and analyzing the current direction in the BMS active balancing process, so that the current direction of the BMS in the active balancing process and the consistency of the controlled switch are controlled, the potential safety hazard caused by inconsistent high-voltage single batteries of the new energy automobile can be reduced, the balancing of the high-voltage single batteries of the new energy automobile is effectively realized, the reliability of the BMS active balancing is improved, and the service life of the battery pack is prolonged.
There is further provided a current commutation control method of a BMS active balancing system corresponding to an automobile according to an embodiment of the present invention, as shown in fig. 8, which is a schematic flow chart of an embodiment of the method of the present invention. The BMS active equalization system includes: a single battery and a DC/DC converter. The DC/DC converter is arranged on the output side of the single battery. The number of the single batteries is more than one, and under the condition that the number of the single batteries is more than two, the single batteries are arranged in series-parallel to form a battery pack.
The current commutation control method of the BMS active equalization system comprises the following steps: step S110 and step S120.
At step S110, the current direction of the unit cell is detected by a detection unit.
At step S120, the control unit controls the working state of the switching tube in the DC/DC converter according to the current direction of the single battery, so that the working state of the switching tube in the DC/DC converter is adjusted to follow the current direction of the single battery, and the current direction of the single battery is matched with or consistent with the working state of the switching tube in the DC/DC converter. The working state of a switching tube in the DC/DC converter comprises the following steps: an off state or an on state.
Wherein, detecting element and the control unit. The detection unit is arranged at the output end of the single battery, in particular between the first output end of the single battery and the second output end of the single battery. A detection unit such as a current direction detection circuit. A control unit, such as a Master Chip (MCU) of the BMS active balancing system. Therefore, the scheme of the invention provides the BMS active balancing current commutation detection method, and the accuracy of the control of the switching tube is determined by detecting and analyzing the current direction in the BMS active balancing process, so that the reliability of active balancing is achieved.
In some embodiments, the DC/DC converter comprises: a transformer, such as transformer T1. The transformer has a primary winding and a secondary winding.
The output end of the single battery is provided with a first output end and a second output end. The first output end of the single battery is connected to the first connection end of the primary winding of the transformer. And the second output end of the single battery is connected to the second connection end of the primary winding of the transformer. One output end is positive and the other output end is negative in the first output end of the single battery and the second output end of the single battery.
Detecting, by a detection unit, a current direction of the single battery, including any one of the following detection situations:
first detection scenario: and under the condition that the voltage of the first output end of the single battery is higher than the voltage of the second output end of the single battery, determining the current direction of the single battery, and recording the current direction from the first output end of the single battery to the second output end of the single battery as a first direction.
Second detection scenario: and under the condition that the voltage of the first output end of the single battery is lower than the voltage of the second output end of the single battery, determining the current direction of the single battery, namely the direction from the second output end of the single battery to the first output end of the single battery, and recording the direction as a second direction.
Fig. 2 is a schematic diagram of an embodiment of an active equalization circuit. The active equalization circuit shown in fig. 2 can be categorized as a constant current controlled DC/DC (i.e., direct current/direct current) converter with bi-directional energy flow. In the constant current control DC/DC converter, a flyback power supply structure is adopted in a main power topology. That is, the main power part of the constant current control DC/DC converter adopts a flyback DC/DC converter topology structure.
Referring to the example shown in fig. 2, the negative voltage BAT-of the unit cell is connected to the second end of the primary winding of the transformer T1 after passing through the primary current direction control circuit. Fig. 7 is a schematic diagram of a primary current direction control circuit according to an embodiment. As shown in fig. 7, in the primary current direction control circuit, the output terminal of the negative voltage BAT-of the unit cell is connected to the second terminal of the primary winding of the transformer T1 via the resistor R7 and the capacitor C9. The output end of the negative voltage BAT-of the single battery is also connected to the drain electrode of the MOS tube Q1. The source of the MOS transistor Q1 is connected to the source of the MOS transistor Q2. The drain electrode of the MOS tube Q2 is connected to the second end of the primary winding of the transformer T1. The grid electrode of the MOS tube Q1 is connected to the anode of the diode D1, is connected to the cathode of the diode D1 after passing through the resistor R5, is connected to the grid electrode of the MOS tube Q2, and is also connected to the source electrode of the MOS tube Q2 after passing through the resistor R6. The cathode of the diode D1 serves as the input of the drive signal DRIVER0, the drive signal DRIVER0 being controlled by the main chip or the current direction detection circuit.
In the example shown in fig. 7, the MOS transistors Q1 and Q2 are connected back to back, and the drive signal DRIVER0 is used to control on and off simultaneously. The resistor R5 is a driving resistor and is the same as the damping of the configuration driving circuit. The resistor R6 is used for preventing the mis-conduction and accelerating the discharge of charges between the GS of the MOS tube (namely between the grid electrode and the source electrode of the MOS tube), and the diode D1 plays a role in accelerating the turn-off of the MOS tube.
In some embodiments, the secondary winding of the transformer has a center tap, the winding between the first connection end of the secondary winding of the transformer and the center tap is a first winding, and the winding between the second connection end of the secondary winding of the transformer and the center tap is a second winding.
As shown in fig. 2, in the constant current control DC/DC converter, on the secondary side of the transformer T1:
referring to the example shown in fig. 2, the secondary winding of the transformer T1 is a winding with a center tap. The first end of the secondary winding of the transformer T1 is connected to the anode of the diode D4, is connected to the first common end of the resistor R21 and the resistor R22 after passing through the resistor R23 and the capacitor C23, and is also connected to the drain electrode of the MOS tube Q3. The output end of the primary side current sampling circuit is used as the primary side current output end of the transformer T1, and the sampled primary side current I_yuanbian of the transformer T1 can be output to a main chip (such as an MCU).
And the control unit is used for controlling the working state of a switching tube in the DC/DC converter according to the current direction of the single battery, and the control unit comprises any one of the following control conditions:
first control scenario: and the control unit is used for controlling the switching tube in the DC/DC converter under the condition that the current direction of the single battery is the first direction, so that the first winding of the secondary winding of the transformer works and the second winding of the secondary winding of the transformer does not work.
Second control scenario: and the control unit is used for controlling the switching tube in the DC/DC converter under the condition that the current direction of the single battery is the second direction, so that the first winding of the secondary winding of the transformer does not work and the second winding of the secondary winding of the transformer works.
Referring to the example shown in fig. 7, the MOS transistors Q1 and Q2 on the single cell side are connected back to back, that is, the sources, i.e., the S poles, of the two tubes are connected together, the gates, i.e., the G poles, of the two tubes are connected together, and the two MOS transistors are driven simultaneously by using the same driving signal DRIVER0 to adapt to the positive and negative changes of the voltage. Also, because the voltage direction of the battery core side can change, the 24V power supply side needs to adopt two windings (namely an upper winding and a lower winding of a secondary winding of the transformer T1) to ensure that the voltage at two ends of the 24V storage battery is always positive. On the secondary side of the transformer T1, two ends of the MOS tube are connected in parallel with RC filter circuits for absorbing turn-off voltage peaks. The drive signal DRIVER1 and the drive signal DRIVER2 are in particular output by the main chip. On the secondary side of the transformer T1, the driving circuits of the MOS transistor Q3 and the MOS transistor Q4 are similar to those described above, and will not be described again.
When the voltage difference between the single voltages BAT+ and BAT-is positive, the upper winding and the lower winding of the secondary winding of the transformer T1 work and do not work. When the voltage difference between the cell voltages BAT+ and BAT-is negative, the lower winding and the upper winding of the secondary winding of the transformer T1 are not operated. The energy conversion work is completed through the control of the power device. The winding between the first end and the second end of the secondary winding of the transformer T1 is an upper winding. The winding between the second end and the third end of the secondary winding of the transformer T1 is a lower winding.
Therefore, the scheme of the invention realizes the real-time detection of the current direction during the active equalization of the BMS, carries out logic judgment in cooperation with the detection of the current sensor, executes a correct equalization strategy, can reduce the unsafe hidden trouble caused by inconsistent high-voltage single batteries of the new energy automobile, effectively realizes the equalization of the high-voltage single batteries of the new energy automobile, increases the reliability of the active equalization of the BMS, and prolongs the service life of the battery pack. Meanwhile, by adding the balanced current direction detection circuit, the balanced reliability of the battery is improved, and the safety of the new energy automobile is improved.
Since the processes and functions implemented by the method of the present embodiment substantially correspond to the foregoing embodiments, principles and examples of the automobile, the descriptions of the present embodiment are not exhaustive, and reference may be made to the related descriptions of the foregoing embodiments, which are not repeated herein.
Through a large number of experimental verification, adopt the technical scheme of this embodiment, through detecting the analysis to the current direction of BMS initiative balanced in-process, confirm the accuracy of switch tube control to control the uniformity of BMS current direction and the controlled switch of initiative balanced in-process, through increasing balanced current direction detection circuit, improved the balanced reliability of battery, improved new energy automobile's security.
In summary, it is readily understood by those skilled in the art that the above-described advantageous ways can be freely combined and superimposed without conflict.
The above description is only an example of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims (9)

1. A current commutation control device of a BMS active balancing system, wherein the BMS active balancing system comprises: a single battery and a DC/DC converter; the DC/DC converter is arranged on the output side of the single battery;
The current commutation control device of the BMS active equalization system comprises: a detection unit and a control unit; wherein, the liquid crystal display device comprises a liquid crystal display device,
the detection unit is configured to detect the current direction of the single battery;
the control unit is configured to control the working state of the switching tube in the DC/DC converter according to the current direction of the single battery so as to enable the working state of the switching tube in the DC/DC converter to be adjusted along with the current direction of the single battery;
the detection unit includes: the device comprises an optocoupler module, a first current limiting module and a second current limiting module; wherein, the liquid crystal display device comprises a liquid crystal display device,
the first output end of the single battery is connected to the anode of the diode side in the optocoupler module after passing through the first current limiting module; the second output end of the single battery is connected to the cathode of the diode side in the optocoupler module; the collector electrode at the transistor side in the optocoupler module is connected with a direct current power supply after passing through the second current limiting module;
the detection unit determines a current direction of the unit cell, which is a direction from the first output end of the unit cell to the second output end of the unit cell, as a first direction, under a condition that a voltage of the first output end of the unit cell is higher than a voltage of the second output end of the unit cell, and includes:
The optocoupler module is configured to output a low level from a collector electrode at a transistor side in the optocoupler module under the condition that the voltage of a first output end of the single battery is higher than the voltage of a second output end of the single battery, so as to determine the current direction of the single battery, wherein the current direction is the direction from the first output end of the single battery to the second output end of the single battery and is recorded as a first direction;
the detection unit determines a current direction of the unit cell, which is a direction from the second output end of the unit cell to the first output end of the unit cell, as a second direction, under the condition that a voltage of the first output end of the unit cell is lower than a voltage of the second output end of the unit cell, and includes:
the optocoupler module is further configured to output a high level from a collector electrode at a transistor side in the optocoupler module to determine a current direction of the unit cell, which is a direction from the second output end of the unit cell to the first output end of the unit cell, as a second direction, under a condition that a voltage of the first output end of the unit cell is lower than a voltage of the second output end of the unit cell.
2. The current commutation control device of the BMS active balancing system of claim 1, wherein the DC/DC converter comprises: a transformer;
the first output end of the single battery is connected to the first connection end of the primary winding of the transformer; the second output end of the single battery is connected to the second connecting end of the primary winding of the transformer; one output end is positive and the other output end is negative in the first output end of the single battery and the second output end of the single battery;
the detection unit detects the current direction of the single battery, and comprises:
determining the current direction of the single battery under the condition that the voltage of the first output end of the single battery is higher than the voltage of the second output end of the single battery, wherein the current direction is the direction from the first output end of the single battery to the second output end of the single battery and is recorded as a first direction;
and under the condition that the voltage of the first output end of the single battery is lower than the voltage of the second output end of the single battery, determining the current direction of the single battery, namely the direction from the second output end of the single battery to the first output end of the single battery, and recording the direction as a second direction.
3. The current commutation control device of the BMS active balancing system of claim 1, wherein the detection unit further comprises: a filtering module; the filter module is arranged between the collector electrode of the transistor side in the optocoupler module and the ground.
4. The current commutation control device of the BMS active balancing system of claim 2, wherein the secondary winding of the transformer has a center tap, the winding between the first connection end of the secondary winding of the transformer and the center tap is a first winding, and the winding between the second connection end of the secondary winding of the transformer and the center tap is a second winding;
the control unit controls the working state of a switching tube in the DC/DC converter according to the current direction of the single battery, and comprises the following components:
when the current direction of the single battery is the first direction, controlling a switching tube in the DC/DC converter so as to enable a first winding of a secondary winding of the transformer to work and enable a second winding of the secondary winding of the transformer to not work;
and under the condition that the current direction of the single battery is the second direction, controlling a switching tube in the DC/DC converter so as to enable the first winding of the secondary winding of the transformer to be not operated and enable the second winding of the secondary winding of the transformer to be operated.
5. The current commutation control device of the BMS active balancing system of claim 4, wherein the DC/DC converter further comprises: a primary side current direction control module and a secondary side current direction control module;
the primary side current direction control module is arranged in a loop where a primary side winding of the transformer is located; the secondary side current direction control module comprises: the first secondary side control module and the second secondary side control module; the first secondary side control module is arranged in a loop where a first winding of a secondary side winding of the transformer is located; the second secondary side control module is arranged in a loop where a second winding of the secondary side winding of the transformer is located; the primary side current direction control module, the first secondary side control module and the second secondary side control module are all provided with switching tube modules;
wherein, the liquid crystal display device comprises a liquid crystal display device,
the control unit, when the current direction of the single battery is the first direction, controls a switching tube in the DC/DC converter to make the first winding of the secondary winding of the transformer work and make the second winding of the secondary winding of the transformer not work, includes:
when the current direction of the single battery is the first direction, controlling a switching tube in the primary side current direction control module to be switched on, and controlling a switching tube in the first secondary side control module to be switched on and controlling a switching tube in the second secondary side control module to be switched off, so that a first winding of a secondary side winding of the transformer works and a second winding of the secondary side winding of the transformer does not work;
The control unit, when the current direction of the single battery is the second direction, controls the switching tube in the DC/DC converter to make the first winding of the secondary winding of the transformer not work and make the second winding of the secondary winding of the transformer work, including:
and under the condition that the current direction of the single battery is the second direction, controlling a switching tube in the primary side current direction control module to be switched on, and controlling a switching tube in the first secondary side control module to be switched off and controlling a switching tube in the second secondary side control module to be switched on, so that a first winding of a secondary side winding of the transformer is not operated, and a second winding of the secondary side winding of the transformer is operated.
6. An automobile, comprising: current commutation control device of a BMS active balancing system according to any one of claims 1 to 5.
7. A current commutation control method of a BMS active balancing system corresponding to the current commutation control device of the BMS active balancing system according to claim 1, wherein the BMS active balancing system comprises: a single battery and a DC/DC converter; the DC/DC converter is arranged on the output side of the single battery;
The current commutation control method of the BMS active equalization system comprises the following steps:
detecting the current direction of the single battery through a detection unit;
and controlling the working state of the switching tube in the DC/DC converter according to the current direction of the single battery through the control unit so as to enable the working state of the switching tube in the DC/DC converter to be adjusted along with the current direction of the single battery.
8. The method for controlling current commutation of the BMS active balancing system according to claim 7, wherein the DC/DC converter comprises: a transformer;
the first output end of the single battery is connected to the first connection end of the primary winding of the transformer; the second output end of the single battery is connected to the second connecting end of the primary winding of the transformer; one output end is positive and the other output end is negative in the first output end of the single battery and the second output end of the single battery;
detecting, by a detection unit, a current direction of the unit cell, including:
determining the current direction of the single battery under the condition that the voltage of the first output end of the single battery is higher than the voltage of the second output end of the single battery, wherein the current direction is the direction from the first output end of the single battery to the second output end of the single battery and is recorded as a first direction;
And under the condition that the voltage of the first output end of the single battery is lower than the voltage of the second output end of the single battery, determining the current direction of the single battery, namely the direction from the second output end of the single battery to the first output end of the single battery, and recording the direction as a second direction.
9. The method for controlling current commutation of a BMS active balancing system according to claim 8, wherein the secondary winding of the transformer has a center tap, a winding between a first connection end of the secondary winding of the transformer and the center tap is a first winding, and a winding between a second connection end of the secondary winding of the transformer and the center tap is a second winding;
and a control unit for controlling the working state of a switching tube in the DC/DC converter according to the current direction of the single battery, comprising:
when the current direction of the single battery is the first direction, controlling a switching tube in the DC/DC converter so as to enable a first winding of a secondary winding of the transformer to work and enable a second winding of the secondary winding of the transformer to not work;
and under the condition that the current direction of the single battery is the second direction, controlling a switching tube in the DC/DC converter so as to enable the first winding of the secondary winding of the transformer to be not operated and enable the second winding of the secondary winding of the transformer to be operated.
CN202110633158.2A 2021-06-07 2021-06-07 Current commutation control device and method of BMS active equalization system and automobile Active CN113370845B (en)

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