CN116142024A - Method for integrating storage battery protection function of electric vehicle controller - Google Patents

Method for integrating storage battery protection function of electric vehicle controller Download PDF

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Publication number
CN116142024A
CN116142024A CN202211605180.7A CN202211605180A CN116142024A CN 116142024 A CN116142024 A CN 116142024A CN 202211605180 A CN202211605180 A CN 202211605180A CN 116142024 A CN116142024 A CN 116142024A
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battery
midpoint
electric vehicle
phase
series
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黄文新
徐良帅
宋晨风
陈健
陆磊
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Wuxi Aoneng New Energy Technology Co ltd
Nanjing University of Aeronautics and Astronautics
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Wuxi Aoneng New Energy Technology Co ltd
Nanjing University of Aeronautics and Astronautics
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Priority to CN202211605180.7A priority Critical patent/CN116142024A/en
Publication of CN116142024A publication Critical patent/CN116142024A/en
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    • 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
    • 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
    • B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
    • B60L3/0023—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
    • B60L3/0046—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train relating to electric energy storage systems, e.g. batteries or capacitors
    • 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
    • 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

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

The invention discloses a method for integrating a storage battery protection function of an electric vehicle controller, which comprises the steps of integrating the storage battery protection function of controllers of two-wheel, three-wheel and four-wheel vehicles. The neutral point of the three-phase winding of the driving motor of the electric vehicle is led out and is connected with the DC bus capacitor of the controller and the voltage midpoint of the battery pack, and the inverter circuit of the controller is a conventional three-phase inverter bridge. The controller provided by the invention has a certain battery protection function, monitors the balance state of the battery pack by collecting the neutral point potential of the battery pack, judges whether the voltage inconsistency phenomenon occurs between the upper and lower sections of series batteries, and performs balanced protection of certain capacity on the batteries by utilizing the zero sequence current of the winding neutral line. The battery protection method is simple, feasible, efficient and reliable, reduces the risk factors caused by overcharge and overdischarge of the battery of the electric vehicle, and provides a feasible scheme for solving the problem of unbalanced protection of the power battery of the low-speed electric vehicle.

Description

Method for integrating storage battery protection function of electric vehicle controller
Technical Field
The invention relates to the technical field of electric vehicle battery protection, in particular to a method for integrating a storage battery protection function by an electric vehicle controller.
Background
The rapid development of the electric vehicle is a key ring for realizing a double-carbon strategy, but the limitation of a power battery per se prevents the transformation and the upgrading of the electric vehicle, and particularly in the production and the use processes of the battery, the safety problems of thermal runaway, explosion and the like of the battery can be caused due to the inconsistency caused by the difference of monomers; in addition, since the amount of the low-speed electric vehicle to be held is large, the safety of the battery becomes a social problem to some extent. Therefore, the research on reliable, efficient and feasible battery balance protection technology is a necessary measure capable of effectively promoting the improvement of the performance of the electric vehicle.
The vehicle-mounted integrated charging system can realize convenient vehicle-mounted charging under the condition of minimally modifying the whole vehicle driving system, greatly reduces the manufacturing cost of the electric vehicle, has good environmental adaptability, and is increasingly widely applied. However, the integrated system can only perform charge and discharge operations on the whole storage battery pack, and cannot realize energy monitoring and balanced protection of each unit cell pack.
If a certain battery pack in the storage battery pack is a weak battery due to performance degradation, the phenomenon that the voltages of all unit batteries are inconsistent can occur, so that the weak battery in the series battery pack is overcharged or overdischarged. At this time, if the battery is still charged and discharged with normal battery voltage, the weak battery will be accelerated to decay, so as to accelerate the service life decay of the whole battery pack, and in extreme cases, the normal operation of the motor and the storage battery system will be affected.
Disclosure of Invention
Aiming at the defects related to the background technology, the invention provides a method for integrating the storage battery protection function of the electric vehicle controller, so that the controller integrates the driving capability and a certain battery protection function, and the risk factors caused by overcharging and overdischarging of a power battery are reduced. Meanwhile, the leading-out of the middle point of the motor winding enables the whole vehicle driving system to have fault-tolerant operation capability of single-phase faults.
The invention adopts the following technical scheme for solving the technical problems:
in a storage battery pack configured for an electric vehicle, except for two wires for leading out positive and negative buses to supply power for the controller, leading out the voltage midpoint of a series battery pack by using the wires, connecting the voltage midpoint of the series battery pack to the midpoints of two series direct current bus capacitors of the electric vehicle controller, and then connecting the midpoints of three-phase windings of a driving motor of the electric vehicle, wherein the topological connection relation among the battery, the controller and the driving motor is used as a topological basis for completing the protection function of the integrated battery;
the stator of the electric vehicle driving motor comprises three-phase windings A, B, C which are uniformly distributed in space, and three-phase resistors R s Three-phase inductance L s Back electromotive force e A 、e B 、e C ；
The inverter circuit comprises a power tube T 1 、T 2 、T 3 、T 4 、T 5 And T 6 And its antiparallel diode D 1 、D 2 、D 3 、D 4 、D 5 And D 6 The three-phase windings of the motor are connected with the three-phase inverter bridge, wherein the A-phase windings are connected to T 1 、T 2 Midpoint, B-phase winding is connected to T 3 、T 4 Midpoint, C phase is connected with T 5 、T 6 A midpoint;
the neutral point of the driving motor winding of the electric vehicle is led out, is connected with the middle point of the series storage battery pack and is then connected to the middle points of the two series direct current bus capacitors of the controller.
The system structure takes a controller as a hub for energy bidirectional flow, and realizes topology reconstruction of a system charging mode and a driving mode by inputting/cutting out part of functional modules:
in a charging mode, a direct-current charger is put into a system, and a DC-DC converter formed by a three-phase inverter bridge and a motor winding supplies power to a load battery; and in a driving mode, the direct-current charger is switched out of the system, and the series storage battery pack is used as a direct-current power supply to supply power to the load motor through the three-phase inverter bridge.
Further, by utilizing the characteristics that the zero sequence current of the three-phase motor has the same phase and does not influence the output torque, the zero sequence current is synthesized and output from the neutral point of the motor winding to form the balanced current of the battery; meanwhile, the zero sequence inductance of the motor and the three-phase inverter are equivalently reconstructed into Buck, boost and Buck-Boost converters, and the Buck-Boost converters are used for controlling the magnitude and the direction of balanced current, namely adjusting the electric quantity flowing into or flowing out of the midpoint of the battery, so as to carry out balanced protection on the battery;
the topological structure for battery charge and discharge protection synthesizes the parallel three-phase inductor and the three-phase bridge arm into an equivalent circuit, and comprises the following steps:
if the system works in a charging state, an external direct current charger supplies energy to a load battery, and when weak batteries exist in the series battery units above the midpoint, a reconstruction Buck circuit is utilized to implement voltage reduction operation on an upper-stage battery pack; when weak batteries exist in the series battery units below the midpoint, a reconstruction Buck circuit is utilized to carry out voltage reduction operation on the battery pack at the lower section;
if the system works in a discharging state, the series storage battery pack provides energy for the load motor, and when weak batteries exist in the series storage battery units above the midpoint, the reconstruction Boost circuit is utilized to Boost the upper-stage battery pack; when weak batteries exist in the series battery units below the midpoint, a reconstruction Buck-Boost circuit is utilized to Boost the voltage of the battery pack at the lower stage.
Further, detecting the midpoint voltage of the introduced battery pack by an MCU in the electric vehicle controller, and monitoring whether the midpoint potential deviates or not, so as to judge whether the upper and lower series batteries have inconsistent voltage caused by weak batteries due to performance degradation of a certain battery pack, and if the performances of battery units in the battery packs are consistent, the midpoint voltage is half of the bus voltage; if the battery units in the battery pack have performance differences, the midpoint voltage deviates from half of the bus voltage, different unbalance forms are shown during charge and discharge, and a corresponding balance control method needs to be designed, and the method comprises the following steps of:
in a parking charging state, if the midpoint potential rises, weak batteries exist in the series battery units below the midpoint, the batteries reach critical voltage required to trickle charge in advance due to capacity reduction, and at the moment, midpoint current of the batteries is controlled to flow out, namely zero sequence current of a motor is controlled to flow in;
in the parking charging state, if the midpoint potential is reduced, the weak battery exists in the series battery units above the midpoint, the battery reaches the critical voltage required to trickle charge in advance due to capacity reduction, and the current inflow of the midpoint of the battery is controlled, namely the zero sequence current outflow of the motor is controlled;
in a running discharging state, if the midpoint potential rises, weak batteries exist in the series battery units above the midpoint, the batteries reach critical voltage required to trickle charge in advance due to capacity reduction, and at the moment, midpoint current of the batteries is controlled to flow out, namely zero sequence current of a motor is controlled to flow in;
in the running discharging state, if the midpoint potential drops, it is indicated that a weak battery exists in the series battery units below the midpoint, and the battery reaches the critical voltage required to be trickle charged in advance due to the capacity drop, and at the moment, the midpoint current of the battery is controlled to flow in, namely the zero sequence current of the motor is controlled to flow out.
Further, the neutral point of the motor winding is connected with the midpoint of the series storage battery pack on the basis of topology integrating the battery protection function, so that when the low-speed low-voltage electric vehicle has single-phase faults, the residual two phases continue to work normally with fault-tolerant operation capability
Compared with the prior art, the invention has the following beneficial effects:
1. the invention provides a method for integrating a storage battery protection function of an electric vehicle controller, which realizes the switching of system charging and driving functions by time-sharing multiplexing and reasonable reconstruction of a driving motor winding and an inverter, thereby greatly reducing the cost, the quality and the volume of the electric vehicle;
2. the invention provides a method for integrating a storage battery protection function of an electric vehicle controller, which is characterized in that a zero sequence current path is added on the basis of a conventional controller to complete the topology of integrating the storage battery protection function, so that a weak battery is fully utilized for charge and discharge protection, the service life of the battery is prolonged, the output torque of a motor is not influenced, and the stable and safe running of the electric vehicle during the balanced protection charge and discharge period is ensured;
3. the invention also provides a method for integrating the storage battery protection function of the electric vehicle controller, which utilizes the MCU in the controller to quickly detect the neutral point voltage balance condition of the battery pack, utilizes software programming to control the magnitude and the direction of balanced current for four different unbalanced forms during the charge and discharge period, has simple battery balancing criterion and quick charge and discharge protection response;
4. the invention provides a method for integrating a storage battery protection function by an electric vehicle controller, which is characterized in that when a single-phase fault occurs in an electric vehicle, the fault-tolerant operation function of continuous normal operation of the remaining two phases is realized, one phase is reserved as a standby when a circuit is reconfigured, and the fault-tolerant operation function is used for forming a charge-discharge circuit with the other normal phase when a certain working phase is in fault so as to obtain continuous charge capacity, and the system outage risk caused by the fault is reduced.
In conclusion, the invention has the advantages of simple circuit topology, high response speed, simple control method, strong fault tolerance capability and the like, and is suitable for the use occasions of low-speed electric motor cars with the requirements of prolonging the service life of power batteries, including electric two-wheeled vehicles, three-wheeled vehicles and four-wheeled vehicles.
Drawings
Fig. 1 is an external structural diagram of an electric vehicle controller according to the present invention for accomplishing an integrated battery protection function.
Fig. 2 is a schematic topology diagram of an electric vehicle controller for implementing an integrated battery protection function according to the present invention.
Fig. 3 is a Buck equivalent circuit of the system reconstruction in charging according to the present invention.
FIG. 4 is a Boost and Buck-Boost equivalent circuit of the system reconstruction at discharge according to the present invention.
Detailed Description
The technical scheme of the invention is further described in detail below with reference to the accompanying drawings:
this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the components are exaggerated for clarity.
As shown in fig. 1, in the external structure of the electric vehicle controller integrating the battery protection function, in a storage battery pack configured by a conventional low-voltage electric vehicle, except for two wires for leading out positive and negative buses to supply power to the controller, the voltage midpoint of the series battery pack is led out by the wires, is connected to the midpoints of two series direct current bus capacitors of the electric vehicle controller, and is then connected to the neutral point of a three-phase winding of a driving motor of the electric vehicle, so that the topological connection relationship among the battery, the controller and the driving motor is used as a topological basis for completing the integrated battery protection function.
As shown in fig. 2, the stator of the driving motor of the electric vehicle comprises three-phase windings A, B, C which are uniformly distributed in space and three-phase resistors R s Three-phase inductance L s Back electromotive force e A 、e B 、e C ；
The inverter circuit comprises a power tube T 1 、T 2 、T 3 、T 4 、T 5 And T 6 And its antiparallel diode D 1 、D 2 、D 3 、D 4 、D 5 And D 6 The three-phase windings of the motor are connected with the three-phase inverter bridge, wherein the A-phase windings are connected to T 1 、T 2 Midpoint, B-phase winding is connected to T 3 、T 4 Midpoint, C phase is connected with T 5 、T 6 A midpoint;
the neutral point of the motor winding is led out and connected with the midpoint of the series storage battery pack and then connected to the midpoint of the two series direct current bus capacitors of the controller.
The system structure takes a controller as a hub for energy bidirectional flow, and realizes topology reconstruction of a system charging mode and a driving mode by inputting/cutting out part of functional modules:
in a charging mode, a direct-current charger is put into a system, and a DC-DC converter formed by a three-phase inverter bridge and a motor winding supplies power to a load battery; and in a driving mode, the direct-current charger is switched out of the system, and the series storage battery pack is used as a direct-current power supply to supply power to the load motor through the three-phase inverter bridge.
Based on the topological structure, the invention provides a method for integrating the battery protection function of the electric vehicle controller. The three-phase motor is synthesized to output from the neutral point of the motor winding by utilizing the characteristics that the zero sequence current of the three-phase motor has the same magnitude and phase and does not influence the output torque, so as to form the balanced current of the battery; meanwhile, the zero sequence inductance of the motor and the three-phase inverter are equivalently reconstructed into Buck, boost and Buck-Boost converters, and the Buck-Boost converters are used for controlling the magnitude and the direction of balanced current, namely adjusting the electric quantity flowing into or flowing out of the midpoint of the battery, and carrying out balanced protection with certain capacity on the battery. In order to simplify the system structure, the counter potential generated by the stator winding cutting rotor magnetic field under the stator winding resistance and the driving mode is ignored, and the parallel three-phase inductor and the three-phase bridge arm are combined into an equivalent circuit to develop the battery equalization principle analysis.
As shown in fig. 2, if the system is operating in a charged state, the external dc charger provides energy to the load battery. When the direct current power supply charges the weak battery in an equalizing way, the working principle of the reconstructed Buck step-down circuit is as follows:
when weak batteries exist in the series battery units above the midpoint, the Buck circuit is used for carrying out voltage reduction operation on the upper-stage battery pack. Setting the switching period as Ts, the duty ratio as D, and conducting the power tube T2 in 0-DTs time to form a current path of 'DC power supply anode-battery B1 cathode-zero sequence inductance L0-power tube T2-DC power supply cathode'; in the time of DTs-Ts, the power tube T2 is turned off, the current on the zero sequence inductor L0 cannot change direction immediately, and the freewheeling diode D1 is turned on to form a current path of 'zero sequence inductor L0-diode D1-battery B1 positive electrode-battery B1 negative electrode';
when weak batteries exist in the series battery units below the midpoint, the Buck circuit is used for carrying out voltage reduction operation on the battery pack at the lower stage. Setting the switching period as Ts, the duty ratio as D, and conducting the power tube T1 in 0-DTs time to form a current path of 'DC power supply positive electrode-power tube T1-L0-battery B2 positive electrode-battery B2 negative electrode-DC power supply negative electrode'; in the time of DTs-Ts, the power tube T1 is turned off, the current on the zero sequence inductance L0 cannot change direction immediately, and the freewheeling diode D2 is turned on at the moment to form a current path of 'zero sequence inductance L0-the positive electrode of the battery B2-the negative electrode of the battery B2-the diode D2'.
As shown in fig. 3, if the system is operating in a discharged state, the battery pack provides energy to the load motor. When a normal battery unit charges a weak battery in an equalizing way, the working principles of the Boost-Boost circuit and the Buck-Boost-Buck circuit are as follows:
when weak batteries exist in the series battery units above the midpoint, a Boost circuit is utilized to Boost the upper-stage battery pack. Setting the switching period as Ts, the duty ratio as D, and conducting the power tube T2 in 0-DTs time to form a current path of 'battery B2 positive pole-zero sequence inductance L0-power tube T2-battery B2 negative pole'; in the time of DTs-Ts, the power tube T2 is turned off, the current on the zero sequence inductor L0 cannot change direction immediately, and the freewheeling diode D1 is turned on to form a current path of 'zero sequence inductor L0-diode D1-battery B1 positive electrode-battery B1 negative electrode';
when weak batteries exist in the series battery units below the midpoint, the Buck-Boost circuit is utilized to Boost the voltage of the battery pack at the lower stage. Setting a switching period as Ts, a duty ratio as D, adjusting the duty ratio as D to be more than 0.5, and conducting the power tube T1 in 0-DTs time to form a current path of 'the anode of the battery B1-the power tube T1-the zero sequence inductance L0-the cathode of the battery B1'; in the time of DTs-Ts, the power tube T1 is turned off, the current on the zero sequence inductance L0 cannot change direction immediately, and the freewheeling diode D2 is turned on at the moment to form a current path of 'zero sequence inductance L0-the positive electrode of the battery B2-the negative electrode of the battery B2-D2'.
The invention also discloses a control algorithm for controlling the magnitude and the direction of the battery balancing current (zero sequence current of the motor) by the inverter designed according to the neutral-point potential imbalance information:
the voltage of the midpoint of the battery pack introduced by the increase is detected and detected by the MCU in the electric vehicle controller, and whether the voltage of the midpoint deviates is monitored, so that whether the upper and lower series batteries are inconsistent due to performance degradation of a certain battery pack or not is judged, and the phenomenon of inconsistent voltage caused by weak batteries is caused. If the performances of the battery units in the battery pack are consistent, the midpoint voltage is half of the bus voltage; if the battery units in the battery pack have performance differences, the midpoint voltage deviates from half of the bus voltage, different unbalance forms are shown during charge and discharge, and a corresponding balance control method needs to be designed:
in a parking charging state, if the midpoint potential rises, weak batteries exist in the series battery units below the midpoint, the batteries reach critical voltage required to trickle charge in advance due to capacity reduction, and at the moment, midpoint current of the batteries is controlled to flow out, namely zero sequence current of a motor is controlled to flow in;
in the parking charging state, if the midpoint potential is reduced, the weak battery exists in the series battery units above the midpoint, the battery reaches the critical voltage required to trickle charge in advance due to capacity reduction, and the current inflow of the midpoint of the battery is controlled, namely the zero sequence current outflow of the motor is controlled;
in a running discharging state, if the midpoint potential rises, weak batteries exist in the series battery units above the midpoint, the batteries reach critical voltage required to trickle charge in advance due to capacity reduction, and at the moment, midpoint current of the batteries is controlled to flow out, namely zero sequence current of a motor is controlled to flow in;
in the running discharging state, if the midpoint potential drops, it is indicated that a weak battery exists in the series battery units below the midpoint, and the battery reaches the critical voltage required to be trickle charged in advance due to the capacity drop, and at the moment, the midpoint current of the battery is controlled to flow in, namely the zero sequence current of the motor is controlled to flow out.
In addition, the neutral point of the motor winding is connected with the midpoint of the battery pack, so that the low-speed low-voltage electric vehicle controller has fault-tolerant operation capability of continuously and normally working the residual two phases when single-phase faults occur.
When the electric vehicle is in a parking charging state, the motor driving system is reconfigured into a Buck circuit, and when the three-phase winding works normally, the voltage reduction operation can be realized only by one phase, and the other two phases are used for standby; when any one phase fails, the standby phase and the normal phase can still be combined to form the Buck converter, so that the overcharge of the weak battery is prevented, and the balanced charging capacity of the motor when the single-phase failure occurs is obtained. For example, when A, B two phases normally participate in operation, if a phase a fails, a standby phase C and a normal phase B are started to form a Buck converter, and the control of the balanced current is continued.
When the electric vehicle is in a driving discharge state, the motor driving system is reconfigured into a Boost circuit and a Buck-Boost circuit, and when the three-phase winding works normally, the boosting operation can be realized only by two phases of the three-phase winding, and the rest one phase is used for standby; when any one phase fails, the standby phase and the normal phase can still be combined to form a Boost converter and a Buck-Boost converter, so that overdischarge of a weak battery is prevented, and the balanced charging capacity of the motor when single-phase failure occurs is obtained. For example, when A, B two phases normally participate in operation, if the A phase fails, the combination of the C phase of the standby phase and the B phase of the normal phase is started to form a Boost converter and a Buck-Boost converter, and the control of the balanced current is continued.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
While the foregoing is directed to embodiments of the present invention, other and further details of the invention may be had by the present invention, it should be understood that the foregoing description is merely illustrative of the present invention and that no limitations are intended to the scope of the invention, except insofar as modifications, equivalents, improvements or modifications are within the spirit and principles of the invention.

Claims (4)

1. The method for integrating the storage battery protection function by the electric vehicle controller is characterized by comprising the following steps of: in a storage battery pack configured for the electric vehicle, except for two wires for leading out positive and negative buses to supply power for a controller, leading out the voltage midpoint of the series battery pack by using the wires, connecting the voltage midpoint of the series battery pack to the midpoints of two series direct current bus capacitors of the controller of the electric vehicle, and then connecting the voltage midpoint of the series direct current bus capacitors to the neutral point of a three-phase winding of a driving motor of the electric vehicle, wherein the topological connection relation among the battery, the controller and the driving motor is used as a topological basis for completing the protection function of the integrated battery;
the stator of the electric vehicle driving motor comprises three-phase windings A, B, C which are uniformly distributed in space, and three-phase resistors R s Three-phase inductance L s Back electromotive force e A 、e B 、e C ；
The inverter circuit comprises a power tube T 1 、T 2 、T 3 、T 4 、T 5 And T 6 And its antiparallel diode D 1 、D 2 、D 3 、D 4 、D 5 And D 6 The three-phase windings of the motor are connected with the three-phase inverter bridge, wherein the A-phase windings are connected to T 1 、T 2 Midpoint, B-phase winding is connected to T 3 、T 4 Midpoint, C phase is connected with T 5 、T 6 A midpoint;
the neutral point of the driving motor winding of the electric vehicle is led out, is connected with the middle point of the series storage battery pack and is then connected to the middle points of the two series direct current bus capacitors of the controller.
2. The method for integrating a battery protection function of an electric vehicle controller according to claim 1, wherein: the three-phase motor is synthesized to output from the neutral point of the motor winding by utilizing the characteristics that the zero sequence current of the three-phase motor has the same magnitude and phase and does not influence the output torque, so as to form the balanced current of the battery; meanwhile, the zero sequence inductance of the motor and the three-phase inverter are equivalently reconstructed into Buck, boost and Buck-Boost converters, and the Buck-Boost converters are used for controlling the magnitude and the direction of balanced current, namely adjusting the electric quantity flowing into or flowing out of the midpoint of the battery, so as to carry out balanced protection on the battery;
the topological structure for battery charge and discharge protection synthesizes the parallel three-phase inductor and the three-phase bridge arm into an equivalent circuit, and comprises the following steps:
if the system works in a charging state, an external direct current charger supplies energy to a load battery, and when weak batteries exist in the series battery units above the midpoint, a reconstruction Buck circuit is utilized to implement voltage reduction operation on an upper-stage battery pack; when weak batteries exist in the series battery units below the midpoint, a reconstruction Buck circuit is utilized to carry out voltage reduction operation on the battery pack at the lower section;
if the system works in a discharging state, the series storage battery pack provides energy for the load motor, and when weak batteries exist in the series storage battery units above the midpoint, the reconstruction Boost circuit is utilized to Boost the upper-stage battery pack; when weak batteries exist in the series battery units below the midpoint, a reconstruction Buck-Boost circuit is utilized to Boost the voltage of the battery pack at the lower stage.
3. The method for integrating a battery protection function of an electric vehicle controller according to claim 1, wherein: detecting the midpoint voltage of the battery pack which is introduced by increasing through an MCU in the electric vehicle controller, and monitoring whether the midpoint potential deviates or not, so as to judge whether the voltage inconsistency phenomenon caused by weak batteries due to performance degradation of a certain battery pack occurs in the upper and lower sections of series batteries, and if the performance of battery units in the battery packs is consistent, the midpoint voltage is half of the bus voltage; if the battery units in the battery pack have performance differences, the midpoint voltage deviates from half of the bus voltage, different unbalance forms are shown during charge and discharge, and a corresponding balance control method needs to be designed, and the method comprises the following steps of:
in a parking charging state, if the midpoint potential rises, weak batteries exist in the series battery units below the midpoint, the batteries reach critical voltage required to trickle charge in advance due to capacity reduction, and at the moment, midpoint current of the batteries is controlled to flow out, namely zero sequence current of a motor is controlled to flow in;
in the parking charging state, if the midpoint potential is reduced, the weak battery exists in the series battery units above the midpoint, the battery reaches the critical voltage required to trickle charge in advance due to capacity reduction, and the current inflow of the midpoint of the battery is controlled, namely the zero sequence current outflow of the motor is controlled;
in a running discharging state, if the midpoint potential rises, weak batteries exist in the series battery units above the midpoint, the batteries reach critical voltage required to trickle charge in advance due to capacity reduction, and at the moment, midpoint current of the batteries is controlled to flow out, namely zero sequence current of a motor is controlled to flow in;
in the running discharging state, if the midpoint potential drops, it is indicated that a weak battery exists in the series battery units below the midpoint, and the battery reaches the critical voltage required to be trickle charged in advance due to the capacity drop, and at the moment, the midpoint current of the battery is controlled to flow in, namely the zero sequence current of the motor is controlled to flow out.
4. The method for integrating a battery protection function of an electric vehicle controller according to claim 1, wherein: the neutral point of the motor winding is connected with the midpoint of the series storage battery pack on the basis of topology integrating the battery protection function, so that the low-speed low-voltage electric vehicle has fault-tolerant operation capability of continuously and normally working the residual two phases when single-phase faults occur.
CN202211605180.7A 2022-12-14 2022-12-14 Method for integrating storage battery protection function of electric vehicle controller Pending CN116142024A (en)

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