Charging and discharging management system and method

Abstract

According to the charging and discharging management system and method provided by the invention, when the charger charges the battery unit, the output of the charger passes through the power conversion circuit, and then the output of the power conversion circuit charges the battery unit; when the battery unit discharges the load, the output of the battery unit passes through the power conversion circuit and then discharges the load through the port of the battery pack; during charging, the power conversion circuit controls the voltage of the battery unit to be stabilized at a full voltage value when the battery unit is fully charged; and during discharging, the power conversion circuit ensures that the output of the battery pack meets the lowest working voltage of load working. Through the arrangement, the voltage on the battery can be stabilized at a certain value when the battery is fully charged, so that the charging safety of the battery is improved, and the compatibility of the charger can be improved; and moreover, the voltage of the battery pack port can be ensured to meet the minimum working voltage required by the load work through the power conversion circuit, so that different types of battery units can be compatible.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management, and in particular to a charge and discharge management system and method. Background Art

[0002] Figure 1a The figure shows a schematic diagram of charging a battery cell bat by an AC / DC charger. In this structure, all charging controls are implemented by the AC / DC charger. However, when the specifications of the AC / DC charger and the battery cell bat do not match, there may be an overvoltage on the battery cell bat. When the battery cell bat uses a lithium battery, there may be certain safety hazards in this overvoltage condition. In order to improve safety, there is a solution in the prior art to use sodium ion batteries to replace lithium ion batteries, such as Figure 1b As shown in FIG. 1 , it is a schematic diagram of a battery unit bat supplying power to a load. In the figure, the load is explained by taking a motor drive system as an example. Since the motor drive system needs to work normally within a certain working voltage range, the voltage should not be too low to avoid limiting the motor speed, nor too high to avoid putting pressure on its subsequent equipment. However, the characteristics of sodium ion batteries and lithium ion batteries are different, which results in different output voltage ranges. On the basis of maintaining the same number of battery strings, the minimum voltage of the battery unit bat may be less than the minimum working voltage of the motor drive system, thereby affecting the drive of the motor. Therefore, it is necessary to provide a new solution to solve the problems existing in the prior art. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a charge and discharge management system and method.

[0004] According to a first aspect of the present invention, a charge and discharge management system is provided, comprising a battery cell, an AFE chip, a charging switch tube and a discharging switch tube, wherein the battery cell, the AFE chip, the charging switch tube and the discharging switch tube are all arranged in a battery pack; characterized in that the charging management system further comprises:

[0005] A power conversion circuit, which is disposed in the battery pack and on a path between a port of the battery pack and a charging switch tube and a discharging switch tube connected in series;

[0006] When the charger charges the battery cell, the output of the charger passes through the power conversion circuit, and then the output of the power conversion circuit charges the battery cell; and the power conversion circuit is used to control the voltage of the battery cell when it is fully charged to be stable at the full voltage value;

[0007] When the battery cell discharges the load, the output of the battery cell passes through the power conversion circuit and then discharges to the load through the port of the battery pack; and the power conversion circuit is used to ensure that the output of the battery pack meets the minimum operating voltage of the load.

[0008] Optionally, the power conversion circuit includes a control circuit; when charging the battery unit, the control circuit controls the power conversion circuit to operate in a buck mode;

[0009] Before the battery cell is fully charged, when the charger operates in a constant current mode, the voltage on the battery pack port is controlled to be equal to the sum of the voltage on the battery cell and the first voltage difference;

[0010] After the battery cell is fully charged, the control circuit controls the voltage of the battery cell to be stabilized at a full voltage value when the battery cell is fully charged based on the voltage feedback signal of the battery cell and the voltage reference signal of the battery cell; wherein the voltage reference signal of the battery cell represents the full voltage value of the battery cell.

[0011] Optionally, when the battery unit is discharging, the control circuit controls the power conversion circuit to operate in a boost mode;

[0012] Before the voltage of the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum working voltage of the load, controlling the voltage of the battery pack port to be equal to the sum of the voltage of the battery cell and the second voltage difference;

[0013] When the voltage at the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum operating voltage of the load, the control circuit adjusts the duty cycle in the boost mode so that the voltage at the battery pack port meets the minimum operating voltage of the load.

[0014] Optionally, the power conversion circuit includes a bypass switch tube and a control circuit; the on or off of the bypass switch tube is controlled by the control circuit;

[0015] When the charger matches the battery pack, when charging the battery cell, the control circuit controls the bypass switch tube to be turned on, and before the battery cell is fully charged, the charger charges the battery cell through the bypass switch tube;

[0016] When the battery cell is about to be fully charged or is fully charged, the bypass switch tube is controlled to be turned off, and the power conversion circuit is controlled to operate in a buck mode. The control circuit controls the voltage of the battery cell to be stabilized at a full voltage value when the battery cell is fully charged based on the voltage feedback signal of the battery cell and the voltage reference signal of the battery cell; wherein the voltage reference signal of the battery cell represents the full voltage value of the battery cell.

[0017] Optionally, when the charger does not match the battery pack, when charging the battery cell, the control circuit controls the power conversion circuit to operate in a buck mode, and before the battery cell is fully charged, when the charger operates in a constant current mode, controls the voltage on the battery pack port to be equal to the sum of the voltage on the battery cell and the first voltage difference;

[0018] After the battery cell is fully charged, the control circuit controls the voltage of the battery cell to be stabilized at a full voltage value when the battery cell is fully charged based on the voltage feedback signal of the battery cell and the voltage reference signal of the battery cell; wherein the voltage reference signal of the battery cell represents the full voltage value of the battery cell.

[0019] Optionally, when the battery cell is discharging, the control circuit controls the bypass switch tube to be turned on, and the voltage of the battery cell is output to the port of the battery pack through the bypass switch tube;

[0020] When the voltage of the battery pack port or the voltage of the battery unit is about to drop to or drops to the minimum working voltage of the load, the bypass switch tube is controlled to be turned off, and the power conversion circuit is controlled to work in the boost mode, and the duty cycle of the power conversion circuit in the boost mode is adjusted so that the voltage of the battery pack port meets the minimum working voltage of the load;

[0021] or,

[0022] When the battery cell is discharged, the control circuit controls the power conversion circuit to operate in a boost mode; before the voltage at the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum operating voltage of the load, the voltage at the battery pack port is controlled to be equal to the sum of the voltage of the battery cell and the second voltage difference;

[0023] When the voltage at the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum operating voltage of the load, the control circuit adjusts the duty cycle in the boost mode so that the voltage at the battery pack port meets the minimum operating voltage of the load.

[0024] Optionally, the control circuit includes a first operational amplifier, a second operational amplifier, a third operational amplifier, and a duty cycle adjustment circuit;

[0025] A first input terminal of the first operational amplifier is connected to a voltage feedback signal of the battery cell, and a second input terminal of the first operational amplifier is connected to a voltage reference signal of the battery cell;

[0026] A first input terminal of the second operational amplifier is connected to a current feedback signal of the battery cell, and a second input terminal of the second operational amplifier is connected to a current reference signal of the battery cell;

[0027] The first input terminal of the third operational amplifier is connected to a first reference voltage, and the second input terminal of the third operational amplifier is connected to a voltage feedback signal of the battery pack; the first reference voltage represents the sum of the voltage of the battery cell and the first voltage difference;

[0028] When the power conversion circuit operates in the buck mode to charge the battery unit, the duty cycle adjustment circuit adjusts the duty cycle based on the outputs of the first operational amplifier to the third operational amplifier.

[0029] Optionally, the control circuit includes a fourth operational amplifier, a first input terminal of the fourth operational amplifier is connected to a voltage feedback signal of the battery pack, and a second input terminal of the fourth operational amplifier is connected to a second reference voltage;

[0030] Before the voltage of the battery pack port or the voltage of the battery cell is about to drop to or drops to the lowest working voltage of the load, the second reference voltage represents the sum of the voltage of the battery cell and the second voltage difference;

[0031] When the voltage of the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum operating voltage of the load, the second reference voltage represents a voltage slightly greater than or equal to the minimum operating voltage of the load;

[0032] When the power conversion circuit operates in the boost mode to discharge the battery unit, the duty cycle adjustment circuit adjusts the duty cycle based on the output of the fourth operational amplifier.

[0033] Optionally, the voltage reference signal of the battery cell and the current reference signal of the battery cell are set based on the specifications of the battery cell.

[0034] Optionally, the control circuit further includes a battery cell specification identification module, and the battery cell specification identification module identifies the battery cell specification based on the peripheral pins of the control circuit.

[0035] Optionally, when the power conversion circuit charges the battery unit in the buck mode, before the battery unit is fully charged, the duty cycle in the buck mode is controlled to be a first preset duty cycle.

[0036] Optionally, when the battery cell is discharging and the power conversion circuit is in boost mode, before the voltage at the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum operating voltage of the load, the duty cycle in the boost mode is controlled to be a second preset duty cycle.

[0037] Optionally, the control circuit further includes a matching module identification module, and the matching module identification module detects whether the charger matches the battery unit based on the peripheral pins of the control circuit.

[0038] The present invention also provides a charge and discharge management method, which is applied to the charge and discharge management system described above, and the charge and discharge management method includes:

[0039] A power conversion circuit is provided in the battery pack. When the charger charges the battery cell, the output of the charger passes through the power conversion circuit, and then the output of the power conversion circuit charges the battery cell; when the battery cell discharges the load, the output of the battery cell passes through the power conversion circuit, and then the port of the battery pack discharges the load;

[0040] When the battery cell is charged, the power conversion circuit is used to control the voltage of the battery cell when it is fully charged to stabilize at the full voltage value; when the battery cell is discharged, the power conversion circuit is used to ensure that the output of the battery pack meets the minimum operating voltage of the load.

[0041] The beneficial effects of the present invention include at least:

[0042] The charge and discharge management system and method provided by the present invention are provided with a battery cell and a power conversion circuit in a battery pack. When the charger charges the battery cell, the output of the charger passes through the power conversion circuit, and then the output of the power conversion circuit charges the battery cell; when the battery cell discharges the load, the output of the battery cell passes through the power conversion circuit, and then the output of the power conversion circuit discharges the load through the port of the battery pack; wherein, when the battery cell is charged, the power conversion circuit is used to control the voltage of the battery cell when it is fully charged to be stable at the full voltage value; when the battery cell is discharged, the power conversion circuit is used to ensure that the output of the battery pack meets the minimum working voltage of the load. Through the above-mentioned settings, this article can ensure that the voltage of the battery cell is stable at a certain value when the battery is fully charged, avoid battery overvoltage, so as to improve the safety of battery charging, and improve the compatibility of external chargers; and when the minimum voltage of the battery cell is small, the power conversion circuit can be used to ensure that the voltage of the battery pack port meets the minimum working voltage required for the load to be compatible with different types of battery cells.

[0043] It should be noted that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1a A schematic diagram showing a prior art method of charging a battery unit bat by an AC / DC charger;

[0045] Figure 1b A schematic diagram showing a battery unit BAT supplying power to a load in the prior art is shown;

[0046] Figure 2 A schematic diagram of a charge and discharge management system provided by the present invention is shown;

[0047] Figure 3 Shows Figure 2 A schematic diagram of a medium power conversion circuit;

[0048] Figure 4 A schematic diagram of a charging operation waveform when a battery unit is charged is shown in the present invention;

[0049] Figure 5 A schematic diagram of a discharge working waveform of the present invention when a battery cell is discharged is shown;

[0050] Figure 6 A schematic diagram of a control circuit provided by the present invention is shown;

[0051] Figure 7 Another principle diagram of the charge and discharge management system provided by the present invention is shown. DETAILED DESCRIPTION

[0052] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0053] Figure 2 FIG. 1 is a schematic diagram of a charge and discharge management system provided in this article, which includes a battery cell bat, an AFE chip, a charging switch tube M2 and a discharging switch tube M1, wherein the charging switch tube M2 and the discharging switch tube M1 are both controlled by the AFE chip; the AFE chip can sample the corresponding voltage, temperature, current and other parameter information of the battery cell bat, and implement corresponding control based on the sampled information; Figure 2 As shown in the figure, the battery unit bat, the AFE chip, the charging switch tube M2 and the discharging switch tube M1 are all arranged in the charging pack. The difference from the prior art is that in the present invention, a power conversion circuit is also arranged in the battery pack, and the power conversion circuit is connected to the port of the battery pack, such as Figure 2 As shown in, in the charging direction, when the charger charges the battery cell bat, the output of the charger passes through the power conversion circuit, and then the output of the power conversion circuit charges the battery cell bat; in the discharging direction, when the battery cell bat discharges the load, the output of the battery cell bat passes through the power conversion circuit, and then the port of the battery pack discharges the load; wherein, when charging the battery cell bat, the power conversion circuit is used to control the voltage of the battery cell bat to be stabilized at the full voltage value when it is fully charged, so as to avoid the voltage on the battery cell bat from being over-voltage and causing safety hazards, wherein the size of the full voltage value is related to the specifications of the battery cell; when the battery cell bat is discharging, the power conversion circuit is used to ensure that the output of the battery pack meets the minimum working voltage of the load, so as to avoid the situation in the prior art where the minimum voltage of the battery cell is less than the minimum working voltage of the load, thereby affecting the normal power supply to the load.

[0054] exist Figure 2 In the embodiment, the power conversion circuit also receives a voltage feedback signal Vpack_fb of the battery pack, a voltage feedback signal Vbat_fb of the battery cell bat, and a current feedback signal Ibat_fb of the battery cell bat; the working principle thereof will be further explained below. Figure 3A specific embodiment of the charge and discharge management circuit provided by the present invention illustrates a structure of a power conversion circuit. In this embodiment, the power conversion circuit includes a first switch tube Q1, a second switch tube Q2, an inductor L and a control circuit; the first switch tube Q1 and the second switch tube Q2 are turned on or off by the control circuit; when charging the battery cell bat, the control circuit controls the power conversion circuit to operate in a buck mode, and before the battery cell bat is fully charged, the charger operates in a constant current mode, such as Figure 4 As shown in , before the moment t1 (before Vbat reaches the full voltage value), the voltage Vpack on the battery pack port is controlled to be equal to the sum of the voltage Vbat on the battery cell and the first voltage difference ΔV1. By setting it in this way, in the buck mode, the first switch tube Q1 works in a relatively large duty cycle state, which can improve the system efficiency; after the battery cell bat is fully charged, the control circuit controls the voltage of the battery cell to maintain the full voltage value state based on the voltage feedback signal Vbat_fb of the battery cell and the voltage reference signal Vbat_ref of the battery cell; wherein the voltage reference signal of the battery cell can represent the full voltage value of the battery cell when it is fully charged; that is, to ensure that Vbat is stable at the full voltage value when fully charged, the voltage on the battery cell bat can be prevented from overvoltage. Among them, the first voltage difference ΔV1 can be a preset fixed value, which can simplify the difficulty of circuit design. Of course, the first voltage difference ΔV1 can also be set to a non-fixed value according to the size of the input and output voltages in the buck mode and the multiple angles of improving the system efficiency. After time t1, when Vbat reaches the full voltage value, the voltage on the battery cell will remain stable at the full voltage value; at this time, the charger will switch to constant voltage mode to work. Due to the characteristics of the battery cell, at time t1, when the voltage across the battery cell reaches the full voltage value, the equivalent capacitance inside the battery cell is not fully charged. Therefore, after time t1, the charging current will decrease. When the charging current decreases to a certain value, the equivalent capacitance in the battery cell can be considered to be fully charged, and charging can be stopped at this time.

[0055] It should be noted that when charging the battery cell bat, when the power supply capacity of the charger is sufficient relative to the charging current required by the battery cell bat, the charger can also work in the constant voltage mode to charge the battery cell bat, but at this time, the system loss will increase relative to the above-mentioned solution, which is not conducive to improving efficiency. Therefore, on the basis of ensuring the safe charging of the battery cell bat, the charger can be made to work in the constant current mode to charge the battery cell, and the voltage Vpack of the battery pack can be changed following the voltage Vbat of the battery cell to improve the working efficiency of the system.

[0056] exist Figure 3In the embodiment shown, when the battery cell is discharging, the control circuit controls the power conversion circuit to operate in a boost mode; Figure 5 As shown in the figure, and before the voltage Vpack at the battery pack port or the voltage Vbat of the battery cell is about to drop to or drops to the minimum working voltage of the load ( Figure 5 Taking time t1 as an example), the voltage Vpack at the battery pack port is controlled to be equal to the sum of the voltage Vbat of the battery cell and the second voltage difference ΔV2. By setting it in this way, in the boost mode, Vpack can follow the change of Vbat, and the first switch tube Q1 works in a state of a relatively large duty cycle to improve the system efficiency; when the voltage at the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum working voltage of the load, the control circuit adjusts the duty cycle in the boost mode so that the voltage at the battery pack port meets the minimum working voltage of the load (i.e. Figure 5 Vpack after time t1 can be equal to the minimum working voltage of the load, or can be greater than the minimum working voltage of the load. When it is set to a solution greater than the minimum working voltage, in order to improve working efficiency, it can be set to a voltage value slightly greater than the minimum working voltage of the load.) Among them, the minimum working voltage that is about to drop to the load operation mentioned above means that it is very different from the minimum working voltage of the load operation. The size of the specific value can be set according to actual conditions, and does not affect the understanding of the technical solution by those skilled in the art.

[0057] Further, Figure 6 The figure shows a schematic diagram of a control circuit, which includes a first operational amplifier U1, a second operational amplifier U2, a third operational amplifier U3, a duty cycle adjustment circuit and a first drive generating circuit; a first input terminal of the first operational amplifier U1 is connected to a voltage feedback signal Vbat_fb of a battery cell, and a second input terminal of the first operational amplifier U1 is connected to a voltage reference signal Vbat_ref of a battery cell; a first input terminal of the second operational amplifier U2 is connected to a current feedback signal Ibat_fb of a battery cell, and a second input terminal of the second operational amplifier U2 is connected to a current reference signal Ibat_ref of a battery cell; a first input terminal of the third operational amplifier U3 is connected to a first reference voltage Vref1, and a second input terminal of the third operational amplifier U3 is connected to a voltage feedback signal Vpack_fb of a battery pack; wherein, the first reference voltage Vref1 represents the sum of a voltage Vbat of a battery cell and a first voltage difference ΔV1. Figure 6In the embodiment, a first switch S1 is further provided between the output terminals of the first operational amplifier to the third operational amplifier and the duty cycle adjustment circuit. When the power conversion circuit works in the buck mode to charge the battery unit, the first switch S1 is closed, and the duty cycle adjustment circuit adjusts the duty cycle based on the outputs of the first operational amplifier to the third operational amplifier; the first drive generation circuit outputs drive signals Drv1 and Drv2 based on the duty cycle to control the first switch tube Q1 and the second switch tube Q2 respectively. Figure 6 In the embodiment shown, the output terminals of the first operational amplifier to the third operational amplifier are respectively connected to diodes D1 to D3, that is, in this embodiment, the duty cycle adjustment circuit adjusts the duty cycle based on the minimum value of the output terminals of the first operational amplifier to the third operational amplifier. However, the present invention is not limited to this, and the circuit can also be modified to achieve the same function; for example, by changing the connection of the positive and negative input terminals of the operational amplifier, the duty cycle can also be adjusted based on the maximum value of the output terminals of the first operational amplifier to the third operational amplifier. Further, as Figure 6 As shown in , a first reference voltage generating module is provided inside the control circuit, which receives the voltage feedback signal Vbat_fb of the battery cell and the signal ΔV1' representing the first voltage difference ΔV1, and the first reference signal Vref1 can be set to be equal to the sum of Vbat_fb and ΔV1'. Among them, the voltage reference signal Vbat_ref of the battery cell and the current reference signal Ibat_ref of the battery cell are set based on the specifications of the battery cell. The values ​​of these two signals may be different for different battery cells. Therefore, a battery specification identification module can also be provided inside the control circuit, and the control circuit is also provided with corresponding pins. The battery cell specification identification module realizes the identification of the battery cell specifications based on the peripheral pins of the control circuit, wherein this part of the function can be realized by the existing scheme of the prior art, for example, a pin PIN1 is set on the control circuit, and an external resistor can be connected to the pin PIN1, and the specifications of the battery cell can be identified based on the size of the external resistor. Of course, other methods in the prior art can also be used to realize it, for example, a communication protocol can also be used to send the corresponding battery specification signal to the control circuit through the MCU or AFE chip.

[0058] like Figure 6As shown in, the control circuit also includes a fourth operational amplifier U4, a first input terminal of the fourth operational amplifier U4 is connected to the voltage feedback signal Vpack_fb of the battery pack, and a second input terminal of the fourth operational amplifier U4 is connected to the second reference voltage Vref2; before the voltage Vpack of the battery pack port or the voltage Vbat of the battery cell is about to drop to or drops to the minimum operating voltage of the load, the second reference voltage Vref2 represents the sum of the voltage Vbat of the battery cell and the second voltage difference ΔV2; when the voltage Vpack of the battery pack port or the voltage Vbat of the battery cell is about to drop to or drops to the minimum operating voltage of the load, the second reference voltage Vref2 represents a voltage slightly greater than or equal to the minimum operating voltage of the load. Figure 6 In the embodiment, a second switch S2 is further provided between the output terminal of the fourth operational amplifier and the duty cycle adjustment circuit. When the battery unit is discharged and the power conversion circuit works in the boost mode, the second switch S2 is closed, and the output terminal of the fourth operational amplifier is connected to the input terminal of the duty cycle adjustment circuit. The duty cycle adjustment circuit adjusts the duty cycle based on the output of the fourth operational amplifier. The first drive generation circuit outputs drive signals Drv1 and Drv2 based on the duty cycle to control the first switch tube Q1 and the second switch tube Q2 respectively. Specifically, in Figure 6 In the embodiment shown in , a second reference voltage generating module is provided inside the control circuit, which receives the voltage feedback signal Vbat_fb of the battery cell and the signal ΔV2' representing the second voltage difference ΔV2, and at the same time, also receives the third reference voltage Vref3. In this embodiment, the third reference voltage Vref3 can represent the minimum working voltage of the load, or a voltage value slightly greater than the minimum working voltage of the load. At this time, Vref2 can be equal to the sum of max(Vbat_fb, Vref3) and ΔV2', so that, during discharge, the voltage on the battery pack can be guaranteed to meet the minimum working voltage requirement of the load. Among them, in this embodiment, the generation method of the second reference voltage Vref2 is only one of the embodiments of this article, and this article is not limited to this. As described above, the size of Vref2 can also be set based on the comparison between the voltage Vpack of the battery pack port and the corresponding voltage threshold (the threshold can represent the minimum working voltage of the load, or a voltage value slightly greater than the minimum working voltage of the load).

[0059] It should be noted that Figure 6 Only the circuits or modules mainly related to the present invention are described. Of course, other circuit modules may be provided to implement the core or related technical solutions of the present invention. Figure 6 It is not shown in the figure, but it does not affect the understanding of the scheme by those skilled in the art. Figure 6In the illustrated embodiment, the first input terminal is a negative terminal and the second input terminal is a positive terminal. In other embodiments, other changes may be made to achieve the same function. Figure 6 The circuits and modules shown are just examples in this article, and they can also be modified accordingly to achieve the same function.

[0060] As another embodiment of this invention, before the battery unit is fully charged, the duty cycle of the power conversion circuit in the buck mode can be controlled to be a first preset duty cycle D1, wherein the size of D1 can be set according to the actual application situation. Figure 6 The difference between the embodiment shown in is that in the buck mode, the difference between Vpack and Vbat, i.e., the first voltage difference ΔV1, is a variable. At this time, when Vbat changes, ΔV1 = (Vbat / D1)-Vbat. After the battery cell is fully charged, its control method is the same as Figure 6 The embodiment in, that is, at this time, the system controls the duty cycle through a loop and no longer works at a duty cycle D1. Similarly, when the battery cell is discharging, before the voltage Vpack at the battery pack port or the voltage Vbat of the battery cell is about to drop to or drops to the minimum working voltage of the load, the duty cycle of the power conversion circuit in the boost mode can be controlled to be a second preset duty cycle D2. The size of D2 can be set according to the actual application. At this time, the second voltage difference ΔV2 is also a variable, and its specific value can be obtained according to the relationship between the input and output terminals in the boost mode. When the voltage Vpack at the battery pack port or the voltage Vbat of the battery cell is about to drop to or drops to the minimum working voltage of the load, the system controls the duty cycle through a loop and no longer works at a duty cycle D2.

[0061] As another embodiment of the present invention, Figure 7 Another schematic diagram of the charge and discharge management circuit provided by the present invention is shown in FIG. Figure 5 The difference is that the power conversion circuit is also provided with a bypass switch tube Q3. When the charger matches the battery cell, the control circuit controls the bypass switch tube Q3 to turn on when charging the battery cell. Before the battery cell is fully charged, the charger charges the battery cell through the bypass switch tube Q3. Compared with the method of charging the battery cell in the buck mode described above, the efficiency of the system can be further improved. When the battery cell is about to be fully charged, the bypass switch tube Q3 is controlled to be turned off, and the power conversion circuit is controlled to operate in the buck mode. The control circuit controls the voltage of the battery cell to maintain the full voltage value when it is fully charged based on the voltage feedback signal of the battery cell and the voltage reference signal of the battery cell. When the charger does not match the battery cell, the charging and discharging of the battery cell is in accordance with Figure 5The same method is used in the embodiment, which will not be elaborated in detail here. Specifically, in this embodiment, a matching module identification circuit can be provided in the control circuit to identify whether the specifications of the charger and the battery cell match. When they match, when charging the battery cell, the output drive signal Drv3 controls Q3 to turn on, and the output drive signals Drv1 and Drv2 respectively control Q1 and Q2 to turn off; when it is about to be fully charged, the output drive Drv3 controls Q3 to turn off, and the control circuit generates drive signals Drv1 and Drv2 to control Q1 and Q2 to turn on respectively. When there is no match, Q3 is controlled to be in a state of being turned off all the time. Among them, an external pin can be provided on the control circuit, and the detection of whether the charger and the battery cell match can be realized based on the signal on the external pin; its specific implementation method can adopt the existing solution in the prior art, which will not be elaborated in detail here.

[0062] When the battery cell is discharged, Figure 7 In one embodiment, the control circuit can control the bypass switch tube Q3 to be turned on, and the voltage of the battery cell is output to the port of the battery pack through the bypass switch tube; the load is directly powered through the battery pack port; when the voltage of the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum working voltage of the load, the bypass switch tube is controlled to be turned off, and the power conversion circuit is controlled to work in the boost mode, and the duty cycle of the power conversion circuit in the boost mode is adjusted so that the voltage of the battery pack port meets the minimum working voltage of the load. As another embodiment under discharge, the same Figure 5 The same discharge scheme as in the above description can be found in the specific description and will not be elaborated here.

[0063] The present invention also provides a charge and discharge management method, which can realize the functions of the above charge and discharge management system, which will not be elaborated in detail here.

[0064] In summary, the charge and discharge management system and method provided by the present invention is provided with a battery cell and a power conversion circuit in a battery pack. When the charger charges the battery cell, the output of the charger passes through the power conversion circuit, and then the output of the power conversion circuit charges the battery cell; when the battery cell discharges the load, the output of the battery cell passes through the power conversion circuit, and then the output of the power conversion circuit discharges the load through the port of the battery pack; wherein, when the battery cell is charged, the power conversion circuit is used to control the voltage of the battery cell when it is fully charged to stabilize at the full voltage value; when the battery cell is discharged, the power conversion circuit is used to ensure that the output of the battery pack meets the minimum working voltage of the load. Through the above-mentioned settings, this article can ensure that the voltage of the battery cell is stable at a certain value when the battery is fully charged, avoid battery overvoltage, so as to improve the safety of battery charging, and improve the compatibility of external chargers; and when the minimum voltage of the battery cell is small, the power conversion circuit can be used to ensure that the voltage of the battery pack port meets the minimum working voltage required for the load to work, so as to be compatible with different types of battery cells.

[0065] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. A charge and discharge management system, comprising a battery unit, an AFE chip, a charging switch tube and a discharging switch tube, wherein the battery unit, the AFE chip, the charging switch tube and the discharging switch tube are all arranged in a battery pack; characterized in that: The charging management system further includes: A power conversion circuit, which is disposed in the battery pack and on a path between a port of the battery pack and a charging switch tube and a discharging switch tube connected in series; When the charger charges the battery cell, the output of the charger passes through the power conversion circuit, and then the output of the power conversion circuit charges the battery cell; and the power conversion circuit is used to control the voltage of the battery cell when it is fully charged to be stable at the full voltage value; When the battery cell discharges the load, the output of the battery cell passes through the power conversion circuit and then discharges to the load through the port of the battery pack; and the power conversion circuit is used to ensure that the output of the battery pack meets the minimum operating voltage of the load.

2. The charge and discharge management system according to claim 1, characterized in that: The power conversion circuit includes a control circuit; when charging the battery unit, the control circuit controls the power conversion circuit to operate in a buck mode; Before the battery cell is fully charged, when the charger operates in a constant current mode, the voltage on the battery pack port is controlled to be equal to the sum of the voltage on the battery cell and the first voltage difference; After the battery cell is fully charged, the control circuit controls the voltage of the battery cell to be stabilized at a full voltage value when the battery cell is fully charged based on the voltage feedback signal of the battery cell and the voltage reference signal of the battery cell; wherein the voltage reference signal of the battery cell represents the full voltage value of the battery cell.

3. The charge and discharge management system according to claim 2, characterized in that: When the battery unit is discharging, the control circuit controls the power conversion circuit to operate in a boost mode; Before the voltage of the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum working voltage of the load, controlling the voltage of the battery pack port to be equal to the sum of the voltage of the battery cell and the second voltage difference; When the voltage at the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum operating voltage of the load, the control circuit adjusts the duty cycle in the boost mode so that the voltage at the battery pack port meets the minimum operating voltage of the load.

4. The charge and discharge management system according to claim 1, characterized in that: The power conversion circuit includes a bypass switch tube and a control circuit; the on or off of the bypass switch tube is controlled by the control circuit; When the charger matches the battery pack, when charging the battery cell, the control circuit controls the bypass switch tube to be turned on, and before the battery cell is fully charged, the charger charges the battery cell through the bypass switch tube; When the battery cell is about to be fully charged or is fully charged, the bypass switch tube is controlled to be turned off, and the power conversion circuit is controlled to operate in a buck mode. The control circuit controls the voltage of the battery cell to be stabilized at a full voltage value when the battery cell is fully charged based on the voltage feedback signal of the battery cell and the voltage reference signal of the battery cell; wherein the voltage reference signal of the battery cell represents the full voltage value of the battery cell.

5. The charge and discharge management system according to claim 4, characterized in that: When the charger does not match the battery pack, when charging the battery cell, the control circuit controls the power conversion circuit to operate in a buck mode, and before the battery cell is fully charged, when the charger operates in a constant current mode, controls the voltage on the battery pack port to be equal to the sum of the voltage on the battery cell and the first voltage difference; After the battery cell is fully charged, the control circuit controls the voltage of the battery cell to be stabilized at a full voltage value when the battery cell is fully charged based on the voltage feedback signal of the battery cell and the voltage reference signal of the battery cell; wherein the voltage reference signal of the battery cell represents the full voltage value of the battery cell.

6. The charge and discharge management system according to claim 5, characterized in that: When the battery cell is discharging, the control circuit controls the bypass switch tube to be turned on, and the voltage of the battery cell is output to the port of the battery pack through the bypass switch tube; When the voltage of the battery pack port or the voltage of the battery unit is about to drop to or drops to the minimum working voltage of the load, the bypass switch tube is controlled to be turned off, and the power conversion circuit is controlled to work in the boost mode, and the duty cycle of the power conversion circuit in the boost mode is adjusted so that the voltage of the battery pack port meets the minimum working voltage of the load; or, When the battery cell is discharged, the control circuit controls the power conversion circuit to operate in a boost mode; before the voltage at the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum operating voltage of the load, the voltage at the battery pack port is controlled to be equal to the sum of the voltage of the battery cell and the second voltage difference; When the voltage at the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum operating voltage of the load, the control circuit adjusts the duty cycle in the boost mode so that the voltage at the battery pack port meets the minimum operating voltage of the load.

7. The charge and discharge management system according to claim 3 or 6, characterized in that: The control circuit includes a first operational amplifier, a second operational amplifier, a third operational amplifier, and a duty cycle adjustment circuit; A first input terminal of the first operational amplifier is connected to a voltage feedback signal of the battery cell, and a second input terminal of the first operational amplifier is connected to a voltage reference signal of the battery cell; A first input terminal of the second operational amplifier is connected to a current feedback signal of the battery cell, and a second input terminal of the second operational amplifier is connected to a current reference signal of the battery cell; The first input terminal of the third operational amplifier is connected to a first reference voltage, and the second input terminal of the third operational amplifier is connected to a voltage feedback signal of the battery pack; the first reference voltage represents the sum of the voltage of the battery cell and the first voltage difference; When the power conversion circuit operates in the buck mode to charge the battery unit, the duty cycle adjustment circuit adjusts the duty cycle based on the outputs of the first operational amplifier to the third operational amplifier.

8. The charge and discharge management system according to claim 7, characterized in that: The control circuit includes a fourth operational amplifier, a first input terminal of the fourth operational amplifier is connected to the voltage feedback signal of the battery pack, and a second input terminal of the fourth operational amplifier is connected to a second reference voltage; Before the voltage of the battery pack port or the voltage of the battery cell is about to drop to or drops to the lowest working voltage of the load, the second reference voltage represents the sum of the voltage of the battery cell and the second voltage difference; When the voltage of the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum operating voltage of the load, the second reference voltage represents a voltage slightly greater than or equal to the minimum operating voltage of the load; When the power conversion circuit operates in the boost mode to discharge the battery unit, the duty cycle adjustment circuit adjusts the duty cycle based on the output of the fourth operational amplifier.

9. The charge and discharge management system according to claim 7, characterized in that: The voltage reference signal of the battery cell and the current reference signal of the battery cell are set based on the specifications of the battery cell.

10. The charge and discharge management system according to claim 9, characterized in that: The control circuit further comprises a battery cell specification identification module, and the battery cell specification identification module identifies the battery cell specification based on the peripheral pins of the control circuit.

11. The charge and discharge management system according to claim 2 or 5, characterized in that: When the power conversion circuit charges the battery unit in the buck mode, before the battery is fully charged, the duty cycle in the buck mode is controlled to be a first preset duty cycle.

12. The charge and discharge management system according to claim 3 or 6, characterized in that: When the battery cell is discharging and the power conversion circuit is in boost mode, before the voltage at the battery pack port or the voltage of the battery cell is about to drop to or drops to the minimum operating voltage of the load, the duty cycle in the boost mode is controlled to be a second preset duty cycle.

13. The charge and discharge management system according to claim 5, characterized in that: The control circuit further comprises a matching module identification module, and the matching module identification module detects whether the charger matches the battery unit based on the peripheral pins of the control circuit.

14. A charge and discharge management method, applied to the charge and discharge management system according to any one of claims 1 to 13, the charge and discharge management method comprising: A power conversion circuit is provided in the battery pack. When the charger charges the battery cell, the output of the charger passes through the power conversion circuit, and then the output of the power conversion circuit charges the battery cell; when the battery cell discharges the load, the output of the battery cell passes through the power conversion circuit, and then the port of the battery pack discharges the load; When the battery cell is charged, the power conversion circuit is used to control the voltage of the battery cell when it is fully charged to stabilize at the full voltage value; when the battery cell is discharged, the power conversion circuit is used to ensure that the output of the battery pack meets the minimum operating voltage of the load.

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