CN114865748A

CN114865748A - Battery pack charging and discharging control method, control device and battery device

Info

Publication number: CN114865748A
Application number: CN202210581499.4A
Authority: CN
Inventors: 李砚泉
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-05-26
Filing date: 2022-05-26
Publication date: 2022-08-05

Abstract

The application relates to a battery pack charging and discharging control method, a control device and a battery device, wherein the method comprises the following steps: a battery unit state detection step, namely detecting the voltage, the charging current and the discharging current of a battery unit in the battery pack through a sampling processing control circuit AFE to judge the current battery pack state and output a corresponding control signal; in the charging control step, the micro control unit MCU controls the on-off of a relay and/or a pre-charging pre-discharging current-limiting circuit according to the current battery pack state, and controls the battery pack to switch the charging state; and in the discharging control step, the micro control unit MCU controls the on-off of the relay and/or the pre-charging pre-discharging current-limiting circuit according to the current battery pack state, and controls the battery pack to switch the discharging state. The pre-charging pre-discharging current-limiting circuit can replace an electromagnetic pre-charging relay, so that the reliability of the battery system is improved and the cost is reduced. The circuit is simple, the control logic and a typical lithium battery protection special integrated circuit are good in compatibility and easy to implement, and the current output capacity of the battery pack is improved.

Description

Battery pack charging and discharging control method, control device and battery device

Technical Field

The present disclosure relates to the field of battery pack control technologies, and in particular, to a battery pack charge/discharge control method, a battery pack charge/discharge control device, and a battery device based on a relay.

Background

The development of new energy power generation and new energy electric vehicles drives the research and development of power batteries and energy storage battery devices, in particular to a series high-voltage and high-current power and energy storage lithium battery pack. In order to obtain a certain output voltage and power, a battery pack is generally formed by connecting a plurality of battery units in series and parallel, and when the charging voltage of the battery units is too high or the discharging voltage of the battery units is too low, irreversible damage can be caused to the battery, so that the capacity is reduced, the service life is shortened, and even the battery pack is scrapped. Particularly, the lithium battery is seriously damaged by overcharge and overdischarge. In order to ensure the normal service life, under the normal condition, the lithium battery is provided with a charge-discharge control protection circuit to prevent overcharge and overdischarge.

The traditional lithium battery protection board adopts a micro-power consumption battery unit voltage sampling and MOSFET switch control output circuit AFE (Analog Front-End), and when any battery unit is overcharged, overdischarged and overcurrent, an output loop is turned off. MOSFET is voltage control type spare, can realize microampere level micropower battery management system BMS, satisfies general lithium cell user demand. However, in the case of high power and large current, the MOSFET has a weak impact resistance and a high failure rate.

Chinese utility model CN209088532U, a protection circuit for high current lithium battery, discloses a way of connecting relays in parallel at both ends of MOSFET to improve the charging and discharging current capability of battery device, when the current exceeds the MOSFET channel capability, the relay is switched on and MOSFET is closed, and when the current is smaller, MOSFET is switched on and relay is closed; the relay control circuit has the defects that two circuits are adopted, the relay control needs a current sampling and control output special circuit and control logic software, the universality is low, and the cost is high.

The applicant of the present invention previously filed another chinese invention application CN112769185A for a battery pack charge-discharge control device, a control method and a battery device, and also discloses an overcharge-overdischarge voltage protection circuit with a relay as a switch, wherein the normal state of an interface circuit is a low level, which is typically suitable for a multi-section protection circuit formed by combining a single section of sampling chip, and cannot meet the requirement that the normal state of AFE output DSG and CHG interfaces of a common multi-section sampling control chip is a high level, so a battery protection device with high universality is still needed.

Disclosure of Invention

The embodiment of the application provides a battery pack charging and discharging control method based on a relay, a control device and a battery device, the device solves the problem of high-current charging and discharging protection of a plurality of commonly used protection chips of a lithium battery pack in the prior art, also realizes the functions of pre-charging and pre-discharging current limiting, can replace a pre-charging relay, improves the reliability of a battery system and reduces the cost.

In a first aspect, an embodiment of the present application provides a battery pack charge and discharge control method, including:

a battery unit state detection step, namely detecting the voltage, the charging current and the discharging current of a battery unit in a battery pack through a sampling control circuit AFE to judge the current battery pack state;

and a charging control step, wherein the sampling control circuit AFE and a micro control unit MCU control the on-off of a relay and/or a pre-charging pre-discharging current-limiting circuit according to the current battery pack state to control the battery pack to switch a charging state, and the charging state comprises: a current-limited charging state, a normal charging state and/or an overcharge protection state;

and a discharging control step, wherein the micro control unit MCU controls the on-off of the relay and/or the pre-charging pre-discharging current-limiting circuit according to the current battery pack state and a preset control logic, and controls the battery pack to switch a discharging state, wherein the discharging state comprises the following steps: a current limiting discharge state, a normal discharge state, an overload short circuit discharge protection state, and/or an over discharge protection state.

In some of these embodiments, the charge controlling step includes:

a current-limiting charging step, wherein when the battery unit is in an overdischarge state, a discharge control output circuit DSG outputs a first control signal, a discharge control circuit controls a relay drive circuit to be closed according to the first control signal so as to turn off a relay, and outputs a second control signal to lock the relay through a micro control unit MCU (micro control unit), meanwhile, the second control signal controls a pre-charging and pre-discharging current-limiting circuit to be conducted for current-limiting charging, and the battery pack is switched to a current-limiting charging state so as to enable the voltage of the battery unit to gradually rise;

and a normal charging step, when the voltage of the battery unit in the battery pack reaches or exceeds a preset over-discharge recovery voltage, the micro control unit MCU outputs a third control signal to unlock the relay, and the discharge control output circuit DSG outputs a fourth control signal to the discharge control circuit to control the relay driving circuit to be switched on so as to switch on the relay, the battery pack is switched to a normal charging state, and at the moment, the charging current flows through the battery pack and the relay to carry out normal current charging.

In some embodiments, the charging control step further comprises:

and an overcharge protection control step, in which when the voltage of any one of the battery units reaches a preset overvoltage protection voltage, a charge control output circuit CHG outputs a fifth control signal to the charge control circuit to control the relay driving circuit to be closed so as to turn off the relay, and meanwhile, the precharge pre-discharge current limiting circuit is controlled to be closed through the fifth control signal, so that the battery pack is switched to an overcharge protection state.

In some of these embodiments, the discharge controlling step includes:

in the current-limiting discharging step, when a load is connected and configured to be in current-limiting discharging, the micro control unit MCU outputs a sixth control signal to the discharging control circuit to control the relay driving circuit to be kept closed, meanwhile, the sixth control signal controls the pre-charging pre-discharging current-limiting circuit to be conducted to carry out current-limiting discharging, and the battery pack is switched to a current-limiting discharging state to generate voltage drop through the pre-charging pre-discharging current-limiting circuit;

an overcharge and discharge step, in which, when the battery unit is in an overcharge state, a discharge detection circuit outputs a seventh control signal to the relay driving circuit to control the relay to be turned on through the relay driving circuit, so that the voltage of the battery unit is reduced, and the battery unit is smoothly transited to a normal discharge state, wherein at this time, the output end of the charge control output circuit CHG is a low level signal;

a normal discharge step, when the voltage of the battery unit drops and exits from an overcharge state to enter a normal discharge state, outputting an eighth control signal through the charge control output circuit CHG, controlling the relay drive circuit to be conducted by the charge control circuit according to the eighth control signal to conduct the relay, and switching the battery pack to the normal discharge state; when the battery unit is in a current-limiting discharging state, a ninth control signal is output through the control unit MCU, the discharging control circuit controls the relay driving circuit to be conducted according to the ninth control signal so as to conduct the relay, and the battery pack is switched to a normal discharging state.

In some of these embodiments, the discharge controlling step further comprises:

and an over-discharge protection control step, when the voltage of any battery unit is lower than a preset over-discharge protection voltage, outputting a tenth control signal to control the pre-charge pre-discharge current-limiting circuit to be closed through the discharge control output DSG, and simultaneously controlling the relay driving circuit to close the relay through the discharge control circuit according to the tenth control signal, so that the battery pack is switched to an over-discharge protection state.

In some of these embodiments, the discharge controlling step further comprises:

an abnormal current-limiting discharging step, wherein when the load of the battery pack is overloaded or short-circuited, a load voltage detection circuit outputs a feedback signal to a Micro Control Unit (MCU), the Micro Control Unit (MCU) outputs an eleventh control signal to a discharging control circuit to control the relay driving circuit to be closed so as to turn off the relay, meanwhile, the pre-charging pre-discharging current-limiting circuit is controlled to be conducted through the eleventh control signal to carry out current-limiting discharging, and the battery pack is switched to a current-limiting discharging state;

and an abnormal over-discharge protection step, wherein when the battery pack enters a current-limiting discharge state and exceeds a preset discharge duration, a twelfth control signal is output through the discharge control output DSG to control the pre-charge pre-discharge current-limiting circuit to be closed, meanwhile, the discharge control circuit controls the relay driving circuit to close the relay according to the twelfth control signal, and the battery pack is switched to an overload short-circuit discharge protection state.

In a second aspect, an embodiment of the present application provides a battery pack charge and discharge control apparatus, configured to implement the battery pack charge and discharge control method according to the first aspect, where the battery pack charge and discharge control apparatus includes:

the sampling control circuit AFE is electrically connected with the battery pack and is used for detecting the voltage, the charging current and the discharging current of a battery unit in the battery pack and outputting a control signal;

the relay control circuit is electrically connected with the sampling control circuit AFE;

the relay driving circuit is electrically connected with the relay control circuit;

the relay is electrically connected with the relay driving circuit;

the pre-charging pre-discharging current-limiting circuit is electrically connected with the sampling control circuit AFE, the relay control circuit and the relay output end;

and the micro control unit MCU is electrically connected with the sampling control circuit AFE, the relay control circuit and the pre-charging pre-discharging current-limiting circuit and is used for acquiring the battery pack information acquired by the sampling control circuit AFE and controlling the relay and the pre-charging pre-discharging current-limiting circuit according to the battery pack charging and discharging control method.

The relay control circuit receives the control signal and controls the relay drive circuit according to the control signal, and then controls the relay.

In some of these embodiments, the sampling control circuit AFE includes:

the voltage sampling processing circuit is electrically connected with the battery unit;

the discharge control output circuit DSG is electrically connected with the voltage sampling processing circuit;

the charging control output circuit CHG is electrically connected with the voltage sampling processing circuit;

and the current sampling processing circuit is electrically connected with the voltage sampling processing circuit.

In some of these embodiments, the relay control circuit comprises:

the discharge control circuit is electrically connected with the discharge control output circuit DSG, the voltage sampling processing circuit, the relay drive circuit, the pre-charging pre-discharge current-limiting circuit and the output end PDSG of the micro control unit MCU;

and the charging control circuit is electrically connected with the charging control output circuit CHG, the voltage sampling processing circuit, the relay driving circuit and the pre-charging pre-discharging current-limiting circuit and is connected with the output end of the relay through a discharging detection circuit.

In some embodiments, the battery pack charging and discharging control device further includes a load voltage detection circuit electrically connected to the output terminal of the relay and the MCU.

In some of these embodiments, the discharge control circuit includes:

the output end of the triode V1 is connected with the input end of the relay drive circuit, and the base electrode of the triode V1 is connected with the output end PDSG of the MCU through a resistor R11;

and the anode of the diode D1 is connected with the collector of the triode V1, and the cathode of the diode D1 is connected with the discharge control output circuit DSG.

In some of these embodiments, the charge control circuit comprises:

a collector of the level shifting inverting output grade triode V3 is connected with a grid electrode of a field effect transistor T1 of the relay driving circuit and an output end of the discharge control circuit, and an emitter of the level shifting inverting output grade triode V3 is connected with a low-voltage power supply or a positive pole B + of the battery pack;

and an emitter of the inverting input stage triode V2 is electrically connected with the first contact output end of the relay, a collector of the inverting input stage triode V2 is connected with a base of the level shifting inverting output stage triode V3, and the base of the inverting input stage triode V2 is electrically connected with the charging control output circuit CHG.

In some of these embodiments, the discharge detection circuit includes:

and a base electrode of the discharge detection circuit triode V4 is electrically connected with the output end of the first contact of the relay, an emitter electrode of the discharge detection circuit triode V4 is connected with the second contact of the relay and the cathode B-of the battery pack, and a collector electrode of the discharge detection circuit triode V2 is connected with the collector electrode of the reversed-phase input stage triode V2.

In some of these embodiments, the relay drive circuit includes:

and the grid electrode of the field effect transistor T1 is connected with the discharge control circuit and the charge control circuit, and the source electrode of the field effect transistor T1 is connected with the second contact of the relay and the cathode B-of the battery pack.

In some embodiments, the pre-charge pre-discharge current-limiting circuit comprises:

a current limiting resistor RP;

a source electrode of the discharge switch field effect transistor T2 is connected with a second contact of the relay and is connected with the cathode B of the battery pack through a current sampling resistor Rcs, and a grid electrode of the discharge switch field effect transistor T2 is connected with the discharge control output circuit DSG and/or the output end PDSG of the micro control unit MCU;

the drain electrode of the charging switch field effect transistor T3 is connected with the drain electrode of the discharging switch field effect transistor T2, the source electrode of the charging switch field effect transistor T3 is connected with the voltage sampling processing circuit and the current-limiting resistor RP is connected with the first contact of the relay, and the grid electrode of the charging switch field effect transistor T3 is connected with the charging control output circuit CHG.

In addition, an embodiment of the present application further provides a battery device, including:

the battery pack at least comprises n battery units B1, B2, … … and Bn which are connected in series, and the positive electrode B + of the battery pack is the output end P + of the battery device; and

the battery pack charge and discharge control device according to the second aspect is electrically connected to the battery pack, and the first contact of the relay is the output terminal P-of the battery device and is electrically connected to one end of the pre-charge pre-discharge current-limiting circuit; and a second contact of the relay is electrically connected with the other end of the pre-charging pre-discharging current-limiting circuit and the cathode B-of the battery pack.

In some of these embodiments, a plurality of the battery devices are directly connected in series.

Compared with the related art, the battery pack charging and discharging control method, the control device and the battery device provided by the embodiment of the application have the advantages of high reliability, strong universality and low cost, are particularly suitable for large-current battery pack charging and discharging protection controlled by an MCU (microprogrammed control unit) bus, and can be widely applied to electric automobiles, energy storage inverse substations and the like with lithium batteries as power; on the other hand, the circuit of the embodiment of the application is simple, the control logic is good in compatibility with a typical lithium battery protection special integrated circuit, the implementation is easy, and the current output capacity of the battery pack is improved. In addition, the battery device of the application can be directly connected in series for use, and the requirement of high output voltage occasions is met.

The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below to provide a more thorough understanding of the application.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

fig. 1 is a flowchart of a battery charge and discharge control method according to an embodiment of the present application;

fig. 2 is a flowchart of a substep S2 of a battery pack charge-discharge control method according to an embodiment of the present application;

FIG. 3 is a schematic diagram illustrating the control principle of substep S2 according to an embodiment of the present application;

fig. 4 is a flowchart of a sub-step S3 of a battery pack charge and discharge control method according to an embodiment of the present application;

fig. 5 is another schematic flow chart of a substep S3 of the battery pack charge-discharge control method according to the embodiment of the present application;

FIG. 6 is a schematic diagram illustrating the control principle of substep S3 according to an embodiment of the present application;

fig. 7 is another schematic flow chart of a substep S3 of the battery pack charge-discharge control method according to the embodiment of the present application;

FIG. 8 is a schematic diagram illustrating another control principle of substep S3 according to an embodiment of the present application;

fig. 9 is a schematic diagram of a structure of a battery pack charge and discharge control device according to an embodiment of the present application;

fig. 10 is a schematic circuit diagram of a battery pack charge/discharge control device according to an embodiment of the present application.

In the figure:

1. a sampling control circuit AFE; 2. a discharge control circuit;

3. a charge control circuit; 31. a discharge detection circuit;

4. a relay drive circuit; 5. a pre-charging pre-discharging current-limiting circuit; 6. a relay;

7. a Micro Control Unit (MCU); 8. a load voltage detection circuit; 9. a battery device;

11. a voltage sampling processing circuit; 12. a discharge control output circuit DSG;

13. a charge control output circuit CHG; 14. and a current sampling processing circuit.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments provided in the present application without any inventive step are within the scope of protection of the present application.

It is obvious that the drawings in the following description are only examples or embodiments of the present application, and that it is also possible for a person skilled in the art to apply the present application to other similar contexts on the basis of these drawings without inventive effort. Moreover, it should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another.

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is to be expressly and implicitly understood by one of ordinary skill in the art that the embodiments described herein may be combined with other embodiments without conflict.

Unless defined otherwise, technical or scientific terms referred to herein shall have the ordinary meaning as understood by those of ordinary skill in the art to which this application belongs. Reference to "a," "an," "the," and similar words throughout this application are not to be construed as limiting in number, and may refer to the singular or the plural. The present application is directed to the use of the terms "including," "comprising," "having," and any variations thereof, which are intended to cover non-exclusive inclusions; for example, a process, method, system, article, or apparatus that comprises a list of steps or modules (elements) is not limited to the listed steps or elements, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus. Reference to "connected," "coupled," and the like in this application is not intended to be limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The term "plurality" as referred to herein means two or more. "and/or" describes an association relationship of associated objects, meaning that three relationships may exist, for example, "A and/or B" may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. Reference herein to the terms "first," "second," "third," and the like, are merely to distinguish similar objects and do not denote a particular ordering for the objects.

Overdischarge (over discharge) means over discharge. When the battery discharges, the stored electric energy is gradually released, and the voltage slowly drops. When the voltage drops to a predetermined value, the discharge is stopped and the battery is recharged to restore the energy storage state of the battery. If the discharge is continued below the predetermined value, i.e., if the discharge is excessive, the overdischarge may damage the electrode active material, lose the reaction capability, and shorten the life of the battery.

Overcharge (overcharge) mainly means that the battery continues to be charged after reaching a full charge state during charging, which may cause an increase in the internal pressure of the battery, deformation of the battery, leakage of liquid, and the like, and the performance of the battery may be significantly degraded and deteriorated.

The embodiment provides a battery pack charging and discharging control method. Fig. 1 to 8 are a flowchart and a schematic diagram of a battery pack charge and discharge control method according to an embodiment of the present application, and as shown in fig. 1 to 8, the method includes the following steps:

a battery cell state detection step S1 of detecting the voltage, charging current and discharging current of a battery cell in a battery pack through a sampling control circuit AFE to determine the current battery pack state;

and a charging control step S2, in which the sampling control circuit AFE and the micro control unit MCU control the on-off of a relay and/or a pre-charging pre-discharging current-limiting circuit according to the current battery pack state to control the battery pack to switch the charging state, wherein the charging state comprises: a current-limited charging state, a normal charging state and/or an overcharge protection state; specifically, as shown in fig. 2 to 3, the charge control step S2 includes:

a current-limiting charging step S201, when the battery unit is in an overdischarge state, a discharge control output circuit DSG outputs a first control signal, a discharge control circuit controls a relay drive circuit to be closed according to the first control signal so as to turn off a relay, and outputs a second control signal to lock the relay through the micro control unit MCU, meanwhile, the second control signal controls a pre-charging pre-discharge current-limiting circuit to be conducted for current-limiting charging, and the battery pack is switched to a current-limiting charging state so as to enable the voltage of the battery unit to gradually rise; based on the current-limiting charging step, when the charger is connected to the two ends P + and P-of the battery device adopting the control method of the embodiment of the application, the charging current is subjected to current-limiting charging through the battery pack and the pre-discharging pre-charging current-limiting circuit.

And a normal charging step S202, when the voltages of the battery units in the battery pack all reach or exceed a preset over-discharge recovery voltage, the micro control unit MCU outputs a third control signal to unlock the relay, and the discharge control output circuit DSG outputs a fourth control signal to the discharge control circuit to control the relay driving circuit to be switched on so as to switch on the relay, so that the battery pack is switched to a normal charging state to carry out normal current charging, and at the moment, the charging current flows through the battery pack and the relay to carry out normal current charging.

And an overcharge protection control step S203, when the voltage of any one of the battery units reaches a preset overvoltage protection voltage, a charge control output circuit CHG outputs a fifth control signal to the charge control circuit to control the relay driving circuit to be closed so as to turn off the relay, and meanwhile, the precharge and predischarge current limiting circuit is controlled to be closed through the fifth control signal, so that the battery pack is switched to an overcharge protection state.

And a discharging control step S3, wherein the micro control unit MCU controls the on-off of the relay and/or the pre-charging pre-discharging current-limiting circuit according to the current battery pack state and the preset control logic, and controls the battery pack to switch a discharging state, wherein the discharging state comprises: a current limiting discharge state, a normal discharge state, an overload short circuit discharge protection state, and/or an over discharge protection state. Specifically, as shown in fig. 4 and 6, the discharge control step S3 includes:

a current-limiting discharging step S302, when a load is connected and configured to be in current-limiting discharging, the micro control unit MCU outputs a sixth control signal to the discharging control circuit to control the relay driving circuit to keep closed, meanwhile, the sixth control signal controls the pre-charging pre-discharging current-limiting circuit to be conducted to carry out current-limiting discharging, and the battery pack is switched to a current-limiting discharging state to generate voltage drop through the pre-charging pre-discharging current-limiting circuit; based on the current-limiting discharging step, when the load is connected to the two ends P + and P-of the battery device adopting the control method of the embodiment of the application, the discharging current is discharged through the battery pack and the pre-discharging pre-charging current-limiting circuit to generate voltage drop, and current-limiting discharging is carried out.

And a normal discharge step S304, when the battery unit is in a current-limiting discharge state, outputting a ninth control signal through the control unit MCU, controlling the relay driving circuit to be switched on according to the ninth control signal by the discharge control circuit so as to switch on the relay, and switching the battery pack to a normal discharge state. At this time, the discharge current is discharged by normal current through the battery pack and the relay.

And an over-discharge protection control step S306, when the voltage of any one of the battery units is lower than a preset over-discharge protection voltage, outputting a tenth control signal through the discharge control output DSG to control the pre-charge pre-discharge current-limiting circuit to be closed, and meanwhile, controlling the relay driving circuit to close the relay by the discharge control circuit according to the tenth control signal, so that the battery pack is switched to an over-discharge protection state. After this step is completed, the battery pack may be controlled to skip to step S201 to switch to the current-limiting charging state.

As shown in fig. 5 and 6, the illustrated embodiment is different from the above-described embodiment in that the discharge control step S3 further includes:

an overcharge/discharge step S303, in which a discharge detection circuit outputs a seventh control signal to the relay driving circuit to control the relay to be turned on through the relay driving circuit when the battery unit is in an overcharge state, so as to reduce a voltage of the battery unit; based on the step, the battery pack can directly jump from the overcharged state to the normal discharge state, so that the flexibility of charge and discharge control is improved.

The normal discharge step S304 further includes: when the voltage of the battery unit drops, the battery unit exits from the overcharged state and enters a normal discharging state, an eighth control signal is output through the charging control output circuit CHG, the charging control circuit controls the relay driving circuit to be conducted according to the eighth control signal so as to conduct the relay, and the battery pack is switched to the normal discharging state; at this time, the discharge current is discharged by normal current through the battery pack and the relay.

As shown in fig. 7-8, in some of the embodiments, the discharging control step S3 further includes:

an abnormal current-limiting discharging step S305, when the load of the battery pack is overloaded or short-circuited, such as a transient short-circuit fault, a load voltage detection circuit outputs a feedback signal to the MCU, the MCU outputs an eleventh control signal to the discharging control circuit to control the relay driving circuit to close so as to turn off the relay, and at the same time, the eleventh control signal controls the pre-charge pre-discharge current-limiting circuit to conduct current-limiting discharging, so that the battery pack is switched to a current-limiting discharging state; based on this, when the load is connected to the two ends P + and P-of the battery device adopting the control method of the embodiment of the application, the discharging current is subjected to current-limiting discharging through the battery pack and the pre-charging pre-discharging current-limiting circuit, so as to realize the suppression of surge current caused by the charging of the filter capacitor when the load is connected.

And an abnormal over-discharge protection step S307, when the battery pack enters a current-limiting discharge state and exceeds a preset discharge duration, outputting a twelfth control signal to control the pre-charge pre-discharge current-limiting circuit to be closed through the discharge control output DSG, and simultaneously controlling the relay driving circuit to close the relay according to the twelfth control signal by the discharge control circuit, so that the battery pack is switched to an overload short-circuit discharge protection state.

It should be noted that the steps illustrated in the above-described flow diagrams or in the flow diagrams of the figures may be performed in a computer system, such as a set of computer-executable instructions, and that, although a logical order is illustrated in the flow diagrams, in some cases, the steps illustrated or described may be performed in an order different than here.

An embodiment of the present application further provides a battery pack charge and discharge control device, which is used to implement the battery pack charge and discharge control method according to the above embodiment or preferred embodiment, so as to implement charge and discharge control of a battery device, as shown in fig. 9, the battery pack charge and discharge control device includes: the sampling control circuit AFE1, the discharge control circuit 2, the charge control circuit 3, the relay drive circuit 4, the pre-charging pre-discharge current-limiting circuit 5, the relay 6, the micro control unit MCU7 and the like. It will be understood by those skilled in the art that the battery charge and discharge control device structure shown in fig. 9 does not constitute a limitation of the battery charge and discharge control device, and may include more or fewer components than those shown, or some components may be combined, or a different arrangement of components.

The following describes each component of the battery charge/discharge control device with reference to fig. 9:

the sampling control circuit AFE1 is electrically connected with the battery pack, and the sampling control circuit AFE1 is used for detecting the voltage, the charging current and the discharging current of a battery unit in the battery pack and outputting a control signal; specifically, the sampling control circuit AFE1 includes: the voltage sampling processing circuit 11 is electrically connected with the battery unit; the discharge control output circuit DSG 12 is electrically connected with the voltage sampling processing circuit 11; the charging control output circuit CHG13 is electrically connected with the voltage sampling processing circuit 11; the current sampling processing circuit 13 is electrically connected to the voltage sampling processing circuit 11. Optionally, in order to reduce static loss when applied to the battery device 9, the sampling control circuit AFE1 of the present application may adopt a single-section or multi-section high-precision micro-power-consumption lithium battery management application-specific integrated circuit, for example and without limitation, a lithium battery charging and discharging protection dedicated bus IC such as zhongying corporation SH367309, or a lithium battery dedicated IC of texas instrument TI corporation BQ769X0 series, mitzmi MITSUMI, Panasonic, or the like;

the relay control circuit is electrically connected with the sampling control circuit AFE 1; specifically, the relay control circuit includes: the discharging control circuit 2 is electrically connected with the discharging control output circuit DSG 12, the relay driving circuit 4, the pre-charging pre-discharging current-limiting circuit 5 and the output end PDSG of the micro control unit MCU 7; the charging control circuit 3 is electrically connected with the charging control output circuit CHG13, the voltage sampling processing circuit, the relay drive circuit 4 and the pre-charging pre-discharging current limiting circuit 5, and is connected with the output end of the relay 6 through the discharging detection circuit 31.

As shown in fig. 10, the discharge control circuit 2 of the embodiment of the present application includes: the output end of the triode V1 is connected with the input end of the relay drive circuit 4, and the base electrode of the triode V1 is connected with the output end PDSG of the MCU through a resistor R11; and the anode of the diode D1 is connected with the collector of the triode V1, and the cathode of the diode D1 is connected with the discharge control output circuit DSG 12.

The charge control circuit 3 of the embodiment of the present application includes: a collector of the level shift inverting output stage triode V3 is connected with the grid of a field effect transistor T1 of the relay drive circuit 4 and the output end of the discharge control circuit 2, and an emitter is connected with a low-voltage power supply or the positive pole B + of the battery pack; an emitter of the inverting input stage triode V2 is electrically connected with the output end of the first contact of the relay, specifically, the emitter is connected with a negative electrode P of the battery device 9, a collector is connected with a base of the level shifting inverting output stage triode V3, and the base is electrically connected with the charging control output circuit CHG; and a base electrode of the discharge detection circuit triode V4 is electrically connected with the output end of the first contact of the relay, an emitter electrode of the discharge detection circuit triode V4 is connected with the second contact of the relay and the cathode B-of the battery pack, and a collector electrode of the discharge detection circuit triode V2 is connected with the collector electrode of the reversed-phase input stage triode V2.

The relay driving circuit 4 is electrically connected with the relay control circuit; optionally, the relay driver circuit 4 includes: the grid electrode of the N-type field effect transistor T1 is connected with the discharge control circuit 2 and the charge control circuit 3; specifically, as shown in fig. 10, the gate of the fet T1 is connected to the collector of the level shift inverting output stage transistor V3 and the collector of the transistor V1, the source of the fet T1 is connected to the negative B-of the battery pack, and the drain of the fet T1 is connected to a low voltage power supply or the positive B + of the battery pack through the relay coil RL and its damper diode D5. Optionally, the relay driving circuit 4 of the present application may also be a triode, a P-type fet, or an asic, or any combination thereof.

The relay 6 is electrically connected with the relay drive circuit 4; preferably, the relay 6 of the embodiment of the present application adopts the relay 6 with an arc extinguishing device, as shown in fig. 10, a first contact of the relay 6 is connected to the negative electrode P-, the pre-charge pre-discharge current-limiting circuit 5 and the base of the discharge detection transistor V4 of the battery device 9, and a second contact is connected to the pre-charge pre-discharge current-limiting circuit 5, the current sampling output circuit 14 and the negative electrode B-of the battery pack.

The pre-charging pre-discharging current-limiting circuit 5 is electrically connected with the output ends of the sampling control circuit AFE1, the discharging control circuit 2, the charging control circuit 3, the relay driving circuit 5 and the relay 6; specifically, as shown in fig. 10, the pre-charge pre-discharge current-limiting circuit 5 includes: the current limiting resistor RP, the discharge switch field effect transistor T2 and the charge switch field effect transistor T3; the source electrode of the discharge switch field effect transistor T2 is connected with the second contact of the relay 6, and is connected with the cathode B-of the battery pack through the current sampling resistor Rcs, and the grid electrode of the discharge switch field effect transistor T2 is connected with the discharge control output circuit DSG 12; the drain electrode of the charging switch field effect transistor T3 is connected with the drain electrode of the discharging switch field effect transistor T2, the source electrode of the charging switch field effect transistor T3 is connected with the voltage sampling processing circuit 11, the first contact of the relay 6 and the negative electrode P-of the battery device 9 are connected through the current limiting resistor RP, and the grid electrode of the charging switch field effect transistor T3 is connected with the charging control output circuit CHG 13.

The micro control unit MCU7 is electrically connected to the sampling control circuit AFE1, the discharge control circuit 2 and the pre-charge pre-discharge current-limiting circuit 5, and is configured to acquire the battery pack information acquired by the sampling control circuit AFE1 and control the relay 6 and the pre-charge pre-discharge current-limiting circuit 5 according to the battery pack charge and discharge control method described in the above embodiment. Wherein the relay control circuit receives the control signal and controls the relay drive circuit 4 according to the control signal, and then controls the relay 6.

Based on the structure, the battery pack charging and discharging device provided by the embodiment of the application controls the on-off of the relay 6 and the pre-charging pre-discharging current-limiting circuit 5 based on the matching of the sampling control circuit AFE1, the micro control unit MCU7, the relay control circuit and the relay driving circuit 4, so that the current and voltage protection and output control in the battery pack charging and discharging process are realized, and the pre-charging pre-discharging current-limiting function is realized.

In some embodiments, the battery pack charging and discharging control device further includes a load voltage detection circuit 8 electrically connected to the first contact of the relay 6, the battery pack positive electrode B +, the charging control circuit 3, and the micro control unit MCU 7. Optionally, the load voltage detection circuit 8 of the embodiment of the present application at least includes a voltage comparator to collect the output voltage of the battery pack and feed back the dynamic information thereof to the MCU7, so as to assist the MCU7 in controlling the relay 6 and the pre-charge pre-discharge current-limiting circuit 5, thereby achieving the purpose of suppressing the inrush current and protecting the voltage when the battery pack is connected to the load.

The following description will be made in conjunction with an example of the specific operation principle of the battery pack charge/discharge control device applied to the battery device 9:

in the production or storage and transportation process, the sampling control circuit AFE1 and the micro control unit MCU all output low level signals, the pre-charging pre-discharging current-limiting circuit 5 is closed, the relay 6 is disconnected, and the positive pole P + and the negative pole P-of the battery device 9 are disconnected.

When the positive electrode P + and the negative electrode P-of the battery device 9 are connected to a capacitive load for discharging or the battery pack is charged in an overdischarge state, a large surge current is generated, and a battery unit is damaged or a circuit fault is caused. In order to inhibit surge current, the load voltage detection circuit 8 detects output feedback signals to the micro control unit MCU7 to output voltage instantaneous drop information, the micro control unit MCU7 outputs high level signals to the discharge control circuit 2, the relay drive circuit 4 is cut off, and the output contact of the relay 6 is disconnected; meanwhile, the high level signal is connected to the pre-charging pre-discharging current-limiting circuit 5 to be conducted to carry out current-limiting discharge, and current flows through the battery packs B1-Bn, the current-limiting resistor RP and a load or a charger to limit surge current within a certain range;

after the capacitive load discharges or the battery pack charging surge current passes, the micro control unit MCU7 outputs a low level signal, and the discharge control circuit 2 releases the relay drive circuit 4 according to the low level signal to enable the contact of the relay 6 to be conducted and enter a normal discharge state.

When the positive pole P + and the negative pole P-of the battery device 9 are connected with a load for discharging or connected with a charger for charging, and the voltage and the current of the battery pack are normal, the output end DSG of the discharge control output circuit 12 and the output end CHG of the charge control output circuit 13 are both high level signals, the corresponding discharge control circuit 2 or the corresponding charge control circuit 3 provides voltage bias for the relay drive circuit 4, the relay 6 is switched on, the output contact is closed, and the charge and discharge current flows through the battery pack, the current sampling resistor Rcs and the relay 6 contact.

In the discharging process of the positive electrode P + and the negative electrode P-of the battery device 9 connected with a load, when any battery unit in the battery pack has discharging overcurrent, short circuit or low voltage, the output end DSG of the discharging control output circuit DSG 12 converts the high level into a low level signal; the low level signal closes the relay driving circuit 4 through the discharge control circuit 2, and disconnects the output contact of the relay 6; the low level signal also cuts off the current-limiting discharging circuit through the pre-charging pre-discharging current-limiting circuit 5, so that the load is completely cut off, and the discharging is stopped.

In the charging process of the battery device 9 with the positive electrode P + and the negative electrode P-connected with the charger, when any battery unit in the battery pack has charging overcurrent or overhigh voltage, the output end CHG of the charging control output circuit CHG13 outputs a low level signal; the low level signal closes the relay driving circuit 4 through the charging control circuit 3, and disconnects the output contact of the relay 6; the low level signal also cuts off the current-limiting charging circuit through the pre-charging pre-discharging current-limiting circuit 5, so that the charging circuit is completely cut off, and charging is stopped.

Based on the above, the battery pack charging and discharging control device in the embodiment of the application solves the problems of lithium battery pack charging and discharging protection, capacitive load pre-charging and the like, omits a traditional electromagnetic relay pre-charging current limiting circuit, has high reliability, good universality and low cost, is particularly suitable for large-current battery pack charging and discharging protection, and is widely applied to engineering machinery and agricultural machinery equipment such as electric automobiles, electric forklifts and the like taking lithium batteries as power.

In addition, based on the battery pack charge and discharge control device according to the above embodiment, an embodiment of the present application further provides a battery device 9, including:

the battery pack at least comprises n battery units B1, B2, … … and Bn which are connected in series, and the positive electrode of the battery pack is the output end P + of the battery device 9; and

the battery pack charge and discharge control device according to the second aspect is electrically connected to the battery pack, and the first contact of the relay 6 is the output end P-of the battery device 9 and is electrically connected to one end of the pre-charge pre-discharge current-limiting circuit; the second contact of the relay 6 is electrically connected with the other end of the pre-charging pre-discharging current-limiting circuit and the cathode B-of the battery pack.

It should be noted that a plurality of battery devices 9 according to the embodiments of the present application may be directly connected in series to meet the requirement of the high output voltage.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A battery pack charge-discharge control method is characterized by comprising the following steps:

a battery unit state detection step, wherein a sampling control circuit AFE is used for detecting the voltage, the charging current and the discharging current of a battery unit in a battery pack so as to judge the current battery pack state;

2. The battery pack charge-discharge control method according to claim 1, wherein the charge control step includes:

a current-limiting charging step, wherein when the battery unit is in an overdischarge state, a discharge control output circuit DSG outputs a first control signal, a discharge control circuit controls a relay drive circuit to be closed according to the first control signal so as to turn off a relay, and outputs a second control signal to lock the relay through a micro control unit MCU (micro control unit), and meanwhile, the second control signal controls a pre-charging pre-discharging current-limiting circuit to be conducted to perform current-limiting charging, and the battery pack is switched to a current-limiting charging state;

and a normal charging step, when the voltage of the battery unit in the battery pack reaches or exceeds a preset over-discharge recovery voltage, the micro control unit MCU outputs a third control signal to unlock the relay, and the discharge control output circuit DSG outputs a fourth control signal to the discharge control circuit to control the relay driving circuit to be switched on so as to switch on the relay, and the battery pack is switched to a normal charging state.

3. The battery pack charge-discharge control method according to claim 1 or 2, wherein the charge control step further includes:

and an overcharge protection control step, when the voltage of any battery unit reaches a preset overvoltage protection voltage, a charge control output circuit CHG outputs a fifth control signal to the charge control circuit to control the relay drive circuit to be closed so as to turn off the relay, and meanwhile, the precharge and predischarge current limiting circuit is controlled to be closed through the fifth control signal, so that the battery pack is switched to an overcharge protection state.

4. The battery pack charge-discharge control method according to claim 3, wherein the discharge control step includes:

in the current-limiting discharging step, when a load is connected and configured to be in current-limiting discharging, the micro control unit MCU outputs a sixth control signal to the discharging control circuit to control the relay driving circuit to be kept closed, meanwhile, the sixth control signal controls the pre-charging pre-discharging current-limiting circuit to be conducted to conduct current-limiting discharging, and the battery pack is switched to a current-limiting discharging state;

an overcharge and discharge step, when the battery unit is in an overcharge state, outputting a seventh control signal to the relay drive circuit through a discharge detection circuit so as to control the relay to be conducted through the relay drive circuit, and reducing the voltage of the battery unit;

a normal discharge step, when the voltage of the battery unit drops to exit from an overcharge state and enter a normal discharge state, outputting an eighth control signal through the charge control output circuit CHG, controlling the relay drive circuit to be conducted by the charge control circuit according to the eighth control signal to conduct the relay, and switching the battery pack to the normal discharge state; when the battery unit is in a current-limiting discharging state, a ninth control signal is output through the control unit MCU, the discharging control circuit controls the relay driving circuit to be conducted according to the ninth control signal so as to conduct the relay, and the battery pack is switched to a normal discharging state.

5. The battery pack charge-discharge control method according to claim 4, wherein the discharge control step further includes:

6. The battery pack charge-discharge control method according to claim 4, wherein the discharge control step further includes:

7. A battery charge and discharge control apparatus for realizing the battery charge and discharge control method according to any one of claims 1 to 6, characterized by comprising:

the relay is electrically connected with the relay driving circuit;

and the micro control unit MCU is electrically connected with the sampling control circuit AFE, the relay control circuit and the pre-charging pre-discharging current-limiting circuit.

8. The battery pack charge-discharge control apparatus according to claim 7, wherein the relay control circuit includes:

the discharge control circuit is electrically connected with the sampling control circuit AFE, the relay drive circuit, the pre-charging pre-discharge current-limiting circuit and the micro control unit MCU;

and the charging control circuit is electrically connected with the sampling control circuit AFE and the relay drive circuit and is connected with the pre-charging pre-discharging current-limiting circuit through a discharging detection circuit.

9. The battery pack charge and discharge control device according to claim 8, further comprising a load voltage detection circuit electrically connected to the output terminal of the relay and the MCU.

10. A battery device, comprising:

the battery pack charge and discharge control device according to any one of claims 7 to 9, electrically connected to the battery pack, wherein the first contact of the relay is an output terminal P "of the battery device, and electrically connected to one end of the pre-charge pre-discharge current-limiting circuit; and a second contact of the relay is electrically connected with the other end of the pre-charging pre-discharging current-limiting circuit and the cathode B-of the battery pack.