CN219458704U - Active equalization system for storage battery - Google Patents
Active equalization system for storage battery Download PDFInfo
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- CN219458704U CN219458704U CN202320215193.7U CN202320215193U CN219458704U CN 219458704 U CN219458704 U CN 219458704U CN 202320215193 U CN202320215193 U CN 202320215193U CN 219458704 U CN219458704 U CN 219458704U
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Abstract
The utility model discloses a storage battery active equalization system, which is provided with a BMS main control and a plurality of active equalization BMUs, wherein each active equalization BMU is provided with at least one equalization module, bidirectional equalization is adopted, one end of each equalization module is connected with a corresponding battery box, and the other end of each equalization module is connected with an internal power supply bus V bus_in The balancing device is used for executing balancing actions according to control instructions of BMS master control; the BMS master control is connected with each active equalization BMU through a communication bus for acquiring each BMUActively balancing battery information acquired by the BMU and controlling the balancing module to execute charge balancing, discharge balancing or closing operation according to the battery information; BMS master control and internal power supply busbar V bus_in And an external power supply busbar V bus Is connected for detecting an external power supply busbar V bus Whether or not there is electricity, and when the external power supply busbar V bus When power is lost, at least one battery box can be used for discharging to the internal power supply bus V bus_in Providing power to the system.
Description
Technical Field
The utility model relates to the technical field of battery management, in particular to an active equalization system of a storage battery.
Background
In the power storage devices such as a storage battery and a super capacitor, the single voltage and the capacity of the power generation devices (for convenience of description, the batteries and the battery packs are used for replacement) such as a photovoltaic system are low, the power storage devices are difficult to directly use in a large system, and in practical application, a plurality of batteries are often required to be connected in series to improve the voltage, and a plurality of batteries are connected in parallel to improve the capacity. Due to differences in production environment, process parameters, raw materials and use environment, single batteries have consistency problems, and active equalization is required for energy management.
The active equalization function is usually not independent and is integrated with functions such as battery voltage, current and temperature collection, and the like, as shown in fig. 1, which is a power supply schematic diagram of a BMS system in the prior art, and the active equalization function is integrated in each slave control unit, wherein a power supply is used for providing energy for the slave control units and can be a storage battery, a charging pile, a switching power supply and the like, and the active equalization function is determined according to the requirements of specific application occasions of the BMS; k is a power supply control switch which is controlled by the power supply logic of the whole system; the other ECUs are the general names of all other electric devices in the system which are controlled by the power supply control switch K to supply power; vs is the voltage supplied by the power supply, V bus And controlling the power supply bus voltage of all the electrical equipment after the switch for the power supply.
It is known from the system of fig. 1 that the BMU and other ECUs operate synchronously and shut down synchronously. When the synchronous operation is performed, the power battery is in a dynamic charge and discharge state, referring to fig. 2, which shows a schematic diagram of the influence of the current of the main loop of the power battery on the voltage sampling, and a current I flows through the power battery, wherein V B1 、V Bn For the actual battery voltage, V b1 、V bn To simulate the voltage seen by the front end, V s For the voltage sampled by the MCU, R1 and Rn are equivalent series resistances of each single-string battery, and each string battery is quite different and consists of ohmic internal resistance, polarized internal resistance, connecting strip resistance and contact resistance of the power battery. From this, the technical solution of fig. 1 has at least the following drawbacks:
(1) Voltage V seen by AFE bn ＝V Bn +I.Rn, not the actual cell voltage V Bn While the equivalent series resistances Rn are very different and the main loop current I is varied in real time by V bn Representing the battery voltage V Bn The error is large.
(2) The lithium iron phosphate battery SOC has a large voltage platform between 15% and 85%, and is shown in FIG. 3, which shows the schematic diagrams of the lithium iron phosphate battery SOC and OCV curve, at V a And V b The battery voltage changes little, but the SOC difference may be large, i.e., a small voltage sampling error may cause a large SOC calculation error.
(3) When the battery is in a charging and discharging state, namely in a dynamic state, the sampled voltage is inaccurate, so that an equalization algorithm is easy to misjudge, the equalization direction is wrong, the actual equalization effect is reduced, and even the counter effect is played, so that the method is an important factor for limiting the application and popularization of active equalization.
In order to overcome the above-mentioned technical drawbacks, the prior art proposes a modification, referring to fig. 4, which shows a schematic diagram of connection between active equalization and low-voltage power supply in the prior modification, in which a diode is added between a power switch K and each active equalization BMU, and the active equalization BMU is connected to V after the diode D bus_in The bus is connected with an energy storage battery or a large-capacitance component for storing energy in parallel; other ECUs on the system are connected with V at the front end of the diode bus On the bus.
Because the energy storage battery is arranged, after the power supply switch K is disconnected, the power supply Vs does not provide energy for the BMU any more, and before the BMU is actively balanced, the energy storage battery provides power for the BMU, so that the BMU is conveniently and actively balanced and smoothly started; the instantaneous equalizing charge and the equalizing discharge energy unbalance of the active equalization are absorbed by the energy storage battery, and support V bus_in The bus bar is arranged on the side of the bus bar,providing a stable voltage.
Therefore, when the power control switch K is turned on, other ECU and BMU operate other functions than the active equalization function; when the switch K is disconnected, other ECUs are powered off and turned off, and MCU in BMU detects V bus The power is turned off, an active equalization function is started, and the power battery is turned on to V bus_in The bus bars transmit energy (balance discharge) and supply power to the BMS system, and the balance discharge energy does not supply power to other ECUs due to the presence of the diode D. When the balancing work is carried out, other ECUs do not work, the power battery is in a static state, no large current of the main loop passes through, and the battery voltage sampled by the AFE in the BMU is accurate.
However, the prior art improvement shown in fig. 4 still has the following drawbacks:
(1) The active equalization power on each BMU is supported by the energy storage battery, and the charge and discharge power needs to be strictly matched, otherwise, the energy storage battery is over-discharged or overcharged, and the energy storage battery is damaged, so that the active equalization function is invalid;
(2) The complexity of an equalization algorithm is increased by strictly matching the charge and discharge power, and higher requirements are also put forward on the power accuracy of an active equalization hardware circuit;
(3) Meanwhile, the energy storage battery also needs to be protected by overcharge, overdischarge, overcurrent and short circuit, so that the complexity of the system is further increased, and the reliability of the system is reduced;
(4) The energy storage battery is additionally added to the system, so that the cost and the volume are increased, and the field installation is difficult;
(5) The service life of the energy storage battery is limited, and the active equalization of high-frequency charge and discharge is a bottleneck of the service life of the system.
Therefore, in order to solve the drawbacks of the prior art, it is necessary to propose a technical solution to solve the problems of the prior art.
Disclosure of Invention
In view of the foregoing, it is desirable to provide an active equalization system for a storage battery, so that no energy storage battery is required, the system cost is reduced, and the system reliability is improved.
In order to solve the problems existing in the prior art, the technical scheme of the utility model is as follows:
a storage battery active equalization system is provided with a BMS main control and a plurality of active equalization BMUs, wherein each active equalization BMU is provided with at least one equalization module, bidirectional equalization is adopted, one end of each equalization module is connected with a corresponding battery box, and the other end of each equalization module is connected with an internal power supply bus V bus_in The balancing device is used for executing balancing actions according to control instructions of BMS master control; the BMS main control is connected with each active equalization BMU through a communication bus and is used for acquiring battery information acquired by each active equalization BMU and calculating an equalization algorithm according to the battery information to control the equalization module to execute charge equalization, discharge equalization or closing operation, wherein the charge equalization operation is an internal power supply bus V bus_in The single batteries in the battery box are charged, and the discharging balance is to discharge the single batteries in the battery box to an internal power supply bus V bus_in ；
An external power supply bus V connected with a power supply is also arranged bus External power supply busbar V bus With internal supply bus V bus_in Between which a unidirectional conductive element is arranged to make an internal power supply busbar V bus_in The current of the (a) cannot flow back to the external power supply bus V bus Other ECUs and external power supply bus V bus Is connected with an internal power supply bus V by BMS master control bus_in And an external power supply busbar V bus Is connected for detecting an external power supply busbar V bus Whether or not there is electricity, and when the external power supply busbar V bus When power is lost, at least one battery box can be used for discharging to the internal power supply bus V bus_in Providing power to the system.
As a further improvement, when the power switch K is closed, the power supply supplies power to the external power supply bus V bus Other ECUs work normally, and the BMS system works normally but does not perform an active equalization function; when the power switch K is turned off, the external power supply busbar V bus No power is supplied, other ECUs do not work, and the BMS master control detects V bus After power failure, an equalization algorithm is executed, and an equalization control command is sent to each BMU to execute an equalization action; when the balancing algorithm does not work, the BMS master control controls at least one battery box to discharge to internal power supplyBusbar V bus_in Providing power to the system.
As a further improvement scheme, when the balancing algorithm does not work, the battery cell with the highest BMS master control voltage performs discharging balancing.
As a further improvement, when all the battery boxes meet the consistency requirement, the BMS master control sends control instructions to each BMU to turn off the balancing function.
As a further improvement, the unidirectional conductive element adopts a diode, and the anode of the diode and an external power supply bus V bus Is connected with the cathode and the internal power supply bus V bus_in Is connected with each other.
As a further development, the communication bus is a CAN bus.
As a further improvement scheme, the active equalization BMU charge equalization is output constant current voltage limiting, and the discharge equalization is input constant current, output voltage limiting or output constant current voltage limiting.
As a further improvement, the active equalization BMU charge equalization and the discharge equalization are both constant power.
As a further improvement scheme, when the equalization algorithm works, the discharge equalization output power is larger than the charge equalization input power.
As a further improvement, the active equalization BMU power is configured as follows:
P dsg_o ≥P chg_in and k is dsg ≥k chg Or P dsg_o ＜P chg_in But P is dsg_o *k dsg ≥P chg_in *k chg ；
Wherein P is dsg_o For equalizing discharge output power of single equalizing module, P chg_in Equalizing charge input power, k, for a single active equalization module dsg The number k of discharge equalization channels in the same equalization algorithm period chg And (5) the number of the charge equalization channels in the same equalization algorithm period.
Compared with the prior art, the utility model has the following technical effects:
(1) The application of an energy storage battery can be avoided, the cost is reduced, and the reliability of the system is improved; meanwhile, the field installation is simplified, and the efficiency is improved;
(2) According to the utility model, a battery recovery period is introduced into the period of the equalization algorithm, so that the single voltage value used by the equalization algorithm is more accurate, the SOC calculation is more accurate, and the equalization effect is improved;
(3) The balanced discharging output power of the whole system is ensured to be larger than the balanced charging input power, the balanced charging power and the balanced discharging power are not required to be strictly matched, and the hardware power precision requirement and the balanced algorithm are simplified. P when an anomaly occurs, such as a damaged equalization module, or an equalization algorithm is in error dsg_o *k dsg ≥P chg_in *k chg The power supply balance of the system is destroyed, the system is not operated when power is lost, and the system is balanced and intrinsically safe.
Drawings
Fig. 1 is a power supply schematic diagram of a prior art BMS system.
FIG. 2 is a schematic diagram of the effect of power cell main loop current on voltage sampling.
Fig. 3 is a schematic diagram of SOC and OCV curves for lithium iron phosphate batteries.
Fig. 4 is a schematic diagram of the prior art improved active equalization and low voltage power connection.
Fig. 5 is a schematic diagram of the equalization system and low voltage power connection of the present utility model.
Fig. 6 is a schematic diagram of a periodic time-sharing mechanism of the equalization algorithm according to the present utility model.
FIG. 7 is a diagram illustrating a sample period time-sharing mechanism according to the present utility model.
The utility model will be further illustrated by the following specific examples in conjunction with the above-described figures.
Detailed Description
The technical scheme provided by the utility model is further described below with reference to the accompanying drawings.
Referring to fig. 5, a schematic connection diagram of a battery active equalization system is provided according to the present utility model, wherein the system is provided with a BMS master control and a plurality of active equalization BMUs, each active equalization BMU is provided with at least one equalization module, and each equalization module adopts bidirectional equalization, i.e. low voltage equalizationSide internal power supply busbar V bus_in The power battery can be charged (balanced in charge), and can be discharged to the low-voltage internal power supply bus V bus_in Upper (discharge equalization). One end of the equalization module is connected with the corresponding battery box, and the other end of the equalization module is connected with the internal power supply bus V bus_in The balancing device is used for executing balancing actions according to control instructions of BMS master control; the BMS main control is connected with each active equalization BMU through a communication bus and is used for acquiring single battery information acquired by each active equalization BMU and calculating an equalization algorithm according to the single battery information, issuing an equalization control command to each active equalization BMU, and executing operations such as charge equalization, discharge equalization or closing by the control equalization module, wherein the charge equalization is an internal power supply bus V bus_in The single batteries in the battery box are charged, and the discharging balance is that the single batteries in the battery box are discharged to an internal power supply bus V bus_in 。
An external power supply bus V connected with a power supply is also arranged bus External power supply busbar V bus With internal supply bus V bus_in Between which a unidirectional conductive element is arranged to make an internal power supply busbar V bus_in The current of the (a) cannot flow back to the external power supply bus V bus Other ECUs and external power supply bus V bus Is connected with an internal power supply bus V by BMS master control bus_in And an external power supply busbar V bus Is connected for detecting an external power supply busbar V bus Whether or not there is electricity, and when the external power supply busbar V bus When power is lost, at least one battery box can be used for discharging to the internal power supply bus V bus_in Providing power to the system. Preferably, the unidirectional conductive element is a unidirectional conductive device such as a diode or a MOS transistor.
In the above technical solution, when the power switch K is turned on, the power supply supplies power to the external power supply bus V bus The whole system is formed by an external power supply bus V bus Power supply and other ECU normal work, BMS master control detects V bus Powering up, and not executing an equalization algorithm by the system; when the power switch K is turned off, the external power supply busbar V bus No power supply due to external power supply busbar V bus With internal supply bus V bus_in Between which is arranged a unidirectional conductive elementMeans for making internal supply busbar V bus_in The current of the (a) cannot flow back to the external power supply bus V bus Other ECUs do not operate; because the active equalization BMU adopts bidirectional equalization, at least one battery box can be utilized to discharge to the internal power supply bus V bus_in The BMS system is supplied with power, the BMS master control executes an equalization algorithm, the algorithm result, namely, the control command of each equalization module is issued to each slave control, the BMU executes equalization action, and equalization discharge is carried out on the power supply bus V bus_in Providing energy and keeping the power supply state. Therefore, by adopting the technical scheme, the internal power supply bus V is not needed bus_in An energy storage battery is arranged on the power supply system, and stable power supply can be provided for the system.
Further, when the balancing algorithm does not work, the BMS master control controls the single battery with the highest single voltage to perform discharging balancing. That is, when the balancing algorithm does not work, the BMS master control selects the single battery with the highest voltage in the battery system to perform balanced discharge so as to lead V bus_in In the switching process from the disconnection of the power supply switch K to the active equalization work, the power supply can be kept, so that the active equalization function can be smoothly started. Of course, a plurality of single batteries can be configured to discharge to V at the same time bus_in Providing power to the system.
In the above technical solution, when the balancing algorithm does not work, the BMS master control controls at least one single battery to perform discharge balancing, so that V bus_in In the switching process from the disconnection of the power supply switch K to the active equalization work, the power supply can be kept, so that the active equalization function can be smoothly started, and the internal power supply bus V is not needed bus_in And an energy storage battery is arranged on the upper part. In a preferred embodiment, the BMS master control controls the battery box with the highest cell voltage to perform discharge equalization, and of course, the number of channels for the discharge equalization of the highest cell voltage is not limited to 1, and a plurality of cells with higher cell voltages can be configured to perform discharge equalization at the same time, and in practice, the configuration can be performed according to the relationship between the BMS power supply requirement and the discharge equalization output power.
As a further improvement scheme, when the equalization algorithm works, the discharge equalization output power is larger than the charge equalization input power. So that the internal bus V bus_in The voltage can rise to the output voltage limiting value of balanced discharge, and meanwhile, the energy of balanced discharge can not be transmitted to an external bus V due to the reverse blocking of the diode D bus And a power supply Vs capable of ensuring an internal bus V bus_in Providing power for the system to be stable.
The equalization module in the active equalization BMU charges and equalizes to output constant-current voltage limiting, and discharges and equalizes to input constant current, output voltage limiting or output constant-current voltage limiting. The constant current is used for guaranteeing balanced current, the voltage limiting is used for guaranteeing safety, and the output voltage is guaranteed to be within the safety range of each component. Furthermore, the input and output characteristics of the discharging equalization and the charging equalization of the active equalization BMU can be modified into other modes, such as constant power, so long as the discharging equalization output power of the system is ensured to be larger than the charging equalization input power, and the charging and discharging equalization output has a voltage limiting function.
In practice, the equilibrium discharging output power of the whole system is designed to be larger than but close to the equilibrium charging input power. The power configuration principle of the active equalization system is as follows:
P dsg_o ≥P chg_in and k is dsg ≥k chg Or P dsg_o ＜P chg_in But P is dsg_o *k dsg ≥P chg_in *k chg ；
Wherein P is dsg_o Equalizing discharge output power, P, for a single active equalization module chg_in Equalizing charge input power, k, for a single active equalization module dsg Discharging balance channel number k for whole BMS system in same balance algorithm period chg And (3) charging the balance channel number of the whole BMS system in the same balance algorithm period.
In practice, both combinations may be used to determine the configuration required by the actual system. The number of charge equalization and discharge equalization channels in the equalization algorithm is not limited, the configuration can be carried out according to the charge equalization input power and the discharge equalization output power of an actual equalization module, as long as the equalization discharge output power of the whole system is ensured to be larger than the equalization charge input power, the equalization charge output power can be 1:1,1:2 or other ratios, and the charge equalization power and the discharge equalization output power do not need to be strictly matchedBalance power, simplify hardware power precision requirement and balanced algorithm. P when an anomaly occurs, such as a damaged equalization module, or an equalization algorithm is in error dsg_o *k dsg ≥P chg_in *k chg The power supply balance of the system is destroyed, the system is not operated when power is lost, and the system is balanced and intrinsically safe.
In a preferred embodiment, the equalization algorithm sets a time-sharing mechanism, wherein the equalization algorithm period T is a period including an equalization period T B And battery recovery period T R Equalizing working period T B The working state of each active equalization module is kept unchanged; battery recovery period T R In the middle, the equalization module does not work, and the battery recovery period T is used R The equalization algorithm to be executed in the next cycle is calculated based on the sampled cell voltages. Preferably, each equalization algorithm period T is during a battery recovery period T R After the last voltage sample, the equalization algorithm to be performed for the next cycle is calculated.
Referring to FIG. 6, a schematic diagram of a period time-sharing mechanism of the equalization algorithm according to the present utility model is shown, wherein T is the period of the equalization algorithm, T B To equalize the working period, T R For the battery recovery period, the equalization algorithm is at T R The next equalization algorithm cycle proceeds at the end of (i) i.e., after the last voltage sample in the battery recovery period. Each equalization algorithm period is divided into two phases, wherein the first period is an equalization working period, and during the period, the working state (closing, charge equalization and discharge equalization) of each equalization module is kept unchanged; the second period is the battery recovery period, the equalization does not work, enough time is provided for the battery polarization voltage to recover, and the polarization voltage influence is eliminated. Equalization algorithm uses battery recovery period T R The last sampled single battery voltage is used as a calculation basis, so that the polarization voltage influence caused by the balanced current is eliminated, the battery voltage sampled at the moment is more accurate, the calculated single SOC is more accurate, the balanced algorithm is more accurate, and the balanced effect is better finally.
Further, each equalization algorithm period T is set with a plurality of sampling periods T S Wherein, the working period T is balanced B Mid sampling period T S Number of (d) and battery recoveryPeriod T R Mid sampling period T S The number of (2) is determined by the characteristics of the actual battery. Can be adjusted according to the battery model and the battery type of different manufacturers. Mainly consider the following factors:
a) Proportional relation between the equilibrium current (constant current value) and the power battery capacity: the larger the proportion is, the larger the balanced and adjusted SOC value in each period of the balancing algorithm is, the more easy the balancing is to overshoot, and the energy oscillation is caused, so that the period of the balancing algorithm is not easy to be overlong, and the smaller the period of the balancing algorithm is, the better the period is.
b) Equalizing duty cycle: equalizing period T B Mid sampling period T S The larger the number of the equivalent effective equalization currents (the closer to the constant value of the equalization currents), the higher the power utilization rate of the active equalization circuit, the higher the equalization time efficiency, and the larger the value is.
c) Absolute time of battery recovery period: battery recovery period T R Mid sampling period T S The greater the number of cells, the more sufficient time is available for eliminating the polarization voltage, the greater the value is;
the 3 values described above require a compromise in equalization stability (overshoot), equalization time efficiency and voltage acquisition accuracy.
Referring to FIG. 7, a schematic diagram of a sampling period time-sharing mechanism according to the present utility model is shown, wherein the sampling period T is S Setting a sampling interval period T gap Sampling interval period T gap The sampled voltage value is used for various protections and is not used for an equalization algorithm.
Each equalization period T B In which both charge equalization and discharge equalization synchronously perform the sample period time sharing mechanism of fig. 7, where T S For sampling period, T gap For the intermittent period of sampling, T dsg For equalizing the working time of discharge, T chg For equalizing the working time of charging, T clear In order to balance the time difference between charge and discharge, a section of charge balancing is respectively arranged before and after charge balancing. Each sampling period is divided into two phases, the first period is a gap period, voltage sampling is carried out at the middle point of the period, and the battery polarization voltage is not completely recovered due to short gap period time, and the sampling is obtainedThe voltage value has larger error, and the value is mainly used for various protections and does not do an equalization algorithm; the second period is an equalizing charge-discharge period, voltage sampling is not performed, and equalizing charge is also included in the equalizing charge. If discharge equalization is performed, sampling interval T gap Thereafter is the discharge equalization period T dsg The method comprises the steps of carrying out a first treatment on the surface of the If charge equalization is performed, sampling interval T gap Followed in turn by a time difference T clear Charge equalization period T chg Sum time difference T clear 。
With the above technical solution, in the case that one battery box has a plurality of BMUs, the plurality of BMUs may share a sampling harness, and the harness is resistive, and the voltage drop may be caused by the flowing current. In order to prevent one BMU from sampling battery voltage when the other BMU is in balance, the balance current causes voltage drop on the sampling wire harness, so that the battery voltage is sampled inaccurately, and a gap period T is arranged before and after the voltage sampling moment gap Preventing simultaneous equalization and sampling of different BMUs.
In the technical scheme, the charge equalization is started later than the discharge equalization by T clear Charge equalization closing is earlier than discharge equalization by T clear . The reason for this is:
a) The balanced charge and the balanced discharge are power circuits, larger current is needed to be taken, the input filter capacitor of the BMU is usually smaller, and the balanced charge can pump out the energy storage of the filter capacitor in a very short time, so that the BMS is powered off.
b) Each BMU and the BMS master control are communicated through a CAN bus, the CAN bus is asynchronous communication, and the time accuracy is poor;
c) The equalization algorithm is calculated in the master control, the master control transmits control commands of each equalization module to each slave control (BMU), the equalization control commands transmitted to each slave control by the master control need to be transmitted one by one and cannot be transmitted at the same time, and each slave control receives the equalization control commands and has time difference;
d) Other message information is also arranged on the CAN bus, and when bus competition exists, the equalization control command of some BMUs is delayed;
e) Each BMU has delay from receiving the equalization control command to actually starting equalization, and the delay is influenced by the tasks processed by MCU in the BMU at the time and has larger difference.
To ensure internal power supply busbar V bus_in T is arranged between balanced discharging and balanced charging without power failure clear And the time ensures that the balanced discharge is started in preference to the balanced charge in the whole system, and the balanced discharge is delayed to be closed after the balanced charge. Wherein T is clear Mainly consider the following two factors:
a) The number of BMU in the system, the data quantity and baud rate on the CAN bus, and the speed of BMU response equalization control message. Enough time needs to be reserved, and the charge of any one equalization module in the system is guaranteed to be delayed to be started after the discharge of all equalization modules, and the charge of any one equalization module is closed prior to the discharge of all equalization modules.
b)T clear In the period, the charge equalization does not work, the discharge equalization load is only the power supply of the BMS, and almost no load exists in practice, namely no equalization current exists, and the real equalization effect is only achieved after the charge equalization is started. So T is clear And the current cannot be too long, otherwise, the effective balance current is influenced, and the balance effect is influenced.
In summary, by adopting the technical scheme of the utility model, the working process and principle are as follows:
1) The balancing work (charge balancing, discharge balancing and closing) of all BMUs is uniformly allocated by BMS master control according to the state of charge (SOC) of a monomer;
2) When the power supply switch K is closed (the balancing algorithm does not work), the BMS master control selects the single battery with the highest voltage in the battery system to discharge, so that when the power supply switch K of the system is opened, the BMS is powered down to be closed, and balancing cannot be started;
3) Master control during battery recovery period T R The end of (a) executes an equalization algorithm, and distributes an algorithm result, namely a control command of each equalization module, to each BMU;
4) The equalization execution and algorithm calculation are time-shared as shown in fig. 6, so that the polarization voltage influence of the battery caused by the equalization current is eliminated;
5) The voltage sampling and balancing are time-shared as shown in fig. 7, and if abnormality occurs in one balancing algorithm period, the voltage sampling and balancing can be timely protected;
6) And (3) carrying out time configuration on the equalizing charge and the equalizing discharge according to the diagram 7, and ensuring that any one charge equalizing module in the system is started after all discharge equalizing modules, and any one charge equalizing module is closed prior to all discharge equalizing modules.
When the calculation result of the balancing algorithm shows that all the single batteries meet the consistency requirement, the balancing control command issued by the main control is all closed, and the internal power supply bus V bus_in The BMS system is automatically turned off due to power failure of the BMU due to power consumption.
The above description of the embodiments is only for aiding in the understanding of the method of the present utility model and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the utility model can be made without departing from the principles of the utility model and these modifications and adaptations are intended to be within the scope of the utility model as defined in the following claims.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present utility model. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the utility model. Thus, the present utility model is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The storage battery active equalization system is characterized in that the system is provided with a BMS main control and a plurality of active equalization BMUs, wherein each active equalization BMU is provided with at least one equalization module, bidirectional equalization is adopted, one end of each equalization module is connected with a corresponding battery box, and the other end of each equalization module is connected with an internal power supply bus V bus_in The balancing device is used for executing balancing actions according to control instructions of BMS master control; the BMS master control is connected with each active equalization BMU through a communication bus for obtainingEach of the BMU actively equalizes the battery information collected by the BMU and calculates an equalization algorithm to control the equalization module to execute charge equalization, discharge equalization or closing operation, wherein the charge equalization operation is an internal power supply bus V bus_in The single batteries in the battery box are charged, and the discharging balance is to discharge the single batteries in the battery box to an internal power supply bus V bus_in ；
An external power supply bus V connected with a power supply is also arranged bus External power supply busbar V bus With internal supply bus V bus_in Between which a unidirectional conductive element is arranged to make an internal power supply busbar V bus_in The current of the (a) cannot flow back to the external power supply bus V bus Other ECUs and external power supply bus V bus Is connected with an internal power supply bus V by BMS master control bus_in And an external power supply busbar V bus Is connected for detecting an external power supply busbar V bus Whether or not there is electricity, and when the external power supply busbar V bus When power is lost, at least one battery box can be used for discharging to the internal power supply bus V bus_in Providing power to the system.
2. The battery active equalization system of claim 1, wherein when the power switch K is closed, the power supply is supplied to the external power supply bus V bus Other ECUs work normally, and the BMS system works normally but does not perform an active equalization function; when the power switch K is turned off, the external power supply busbar V bus No power is supplied, other ECUs do not work, and the BMS master control detects V bus After power failure, an equalization algorithm is executed, and an equalization control command is sent to each BMU to execute an equalization action; when the balancing algorithm does not work, the BMS master control controls at least one battery box to discharge to the internal power supply bus V bus_in Providing power to the system.
3. The battery active equalization system of claim 1 or 2, wherein when the equalization algorithm is not operating, the BMS master control controls the cell with the highest control voltage to perform discharge equalization.
4. The battery active equalization system of claim 3, wherein when all of the battery bins meet a consistency requirement, the BMS master sends control instructions to each BMU to shut down the equalization function.
5. The battery active equalization system of claim 3, wherein the unidirectional conductive element is a diode, an anode of the diode and an external power bus V bus Is connected with the cathode and the internal power supply bus V bus_in Is connected with each other.
6. The battery active equalization system of claim 3, wherein the communication bus is a CAN bus.
7. The battery active equalization system of claim 3, wherein the active equalization BMU charges equalization to an output constant current voltage limit and discharges equalization to an input constant current, output voltage limit, or output constant current voltage limit.
8. The battery active equalization system of claim 3, wherein the active equalization BMU charge equalization and discharge equalization are both constant power.
9. The battery active equalization system of claim 3, wherein the equalization algorithm operates with a discharge equalization output power greater than a charge equalization input power.
10. The battery active equalization system of claim 9, wherein the configuration active equalization BMU power is as follows:
P dsg_o ≥P chg_in and k is dsg ≥k chg Or P dsg_o ＜P chg_in But P is dsg_o *k dsg ≥P chg_in *k chg ；
Wherein P is dsg_o For equalizing discharge output power of single equalizing module, P chg_in For the equalization of a single active equalization moduleConstant charge input power, k dsg The number k of discharge equalization channels in the same equalization algorithm period chg And (5) the number of the charge equalization channels in the same equalization algorithm period.
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