Battery charging and discharging system, charging test and discharging test method thereof

Abstract

A battery charging and discharging system includes a bidirectional power supply and a bypass module. The bidirectional power supply provides charging current to charge the battery during charging operation. The bypass module includes a first current path and a second current path connected in parallel. The first current path includes a first resistive unit and the battery coupled to the first resistive unit, and the second current path includes a second resistive unit. The charging current is the sum of a first charging current flowing through the first current path and a second charging current flowing through the second current path. The impedances of the first and second resistive units are adjusted to gradually increase and gradually decrease, respectively, so that the value of the first charging current gradually decreases from a first current value to zero, while the value of the second charging current gradually decreases from zero to a second current value.

Description

[Technical Field]

[0001] This case relates to a battery charging and discharging system and its charging and discharging test methods, and particularly to a system and its charging and discharging test methods that change the current flowing through the battery by adjusting the impedance of the resistive units in the two current paths of the bypass module during battery charging or discharging operations. [Previous Technology]

[0002] In the battery production process, in order to ensure product quality, two procedures must be performed: formation and testing. Formation is the process of charging the battery to activate it after the battery is assembled. Testing is the process of repeatedly charging and discharging the battery after formation to check whether the battery's capacity and charge / discharge performance meet the standard requirements.

[0003] The traditional single-cell formation and testing method, which uses a single battery charge / discharge device, can only form or test one battery at a time, resulting in very low production efficiency. Using multiple battery charge / discharge devices to speed up the product formation and testing process is costly and requires a large footprint. In addition, the single-cell formation and testing method has the disadvantage of high power consumption because the voltage is too low and it is difficult for the battery energy to be fed back to the power supply during discharge. Therefore, in recent years, the series charging architecture for charging and discharging multiple batteries at once has become the mainstream.

[0004] However, due to the differences between individual batteries, they cannot all be charged and discharged simultaneously. To avoid the dangers caused by overcharging or over-discharging, a bypass module must be used in the series charging architecture to switch the batteries that have completed charging and discharging, allowing the charging and discharging current to bypass these batteries and continue charging and discharging only the other batteries that have not yet completed charging and discharging. However, the surge current generated during the switching process can damage circuit components and even the batteries. [Summary of the Invention]

[0005] This invention provides a battery charging and discharging system, comprising a bidirectional power supply and a bypass module. The bidirectional power supply provides charging current to charge a battery during charging operation. The bypass module is coupled between the two ends of the bidirectional power supply and includes a first current path and a second current path connected in parallel. The first current path includes a first resistive unit and a battery coupled to the first resistive unit, and the second current path includes a second resistive unit. The charging current is the sum of a first charging current flowing through the first current path and a second charging current flowing through the second current path, wherein the impedance of the first resistive unit is adjusted to gradually increase, while the impedance of the second resistive unit is adjusted to gradually decrease, causing the value of the first charging current to gradually change from a first current value to zero, and the value of the second charging current to gradually change from zero to a second current value.

[0006] In some embodiments, both the first current value and the second current value are equal to the current value of the charging current.

[0007] In some embodiments, during the discharge operation, the bidirectional power supply will provide a discharge demand command to the battery, and the battery will respond to the discharge demand command by outputting a discharge current, wherein the discharge current is the sum of the first discharge current flowing through the first current path and the second discharge current flowing through the second current path. The impedance of the first resistor unit is adjusted to gradually increase, while the impedance of the second resistor unit is adjusted to gradually decrease, so that the current value of the first discharge current gradually changes from the third current value to zero, and the current value of the second discharge current gradually changes from zero to the fourth current value.

[0008] In some embodiments, both the third current value and the fourth current value are equal to the current value of the discharge current.

[0009] In some embodiments, the first resistor unit includes a first transistor and a second transistor coupled in series, and the second resistor unit includes a third transistor and a fourth transistor coupled in series.

[0010] In some embodiments, the first resistor unit is a first variable resistor, and the second resistor unit is a second variable resistor.

[0011] This invention provides a charging test method for a battery charging and discharging system, used in a battery charging and discharging system having a bidirectional power supply and a bypass module. The bypass module is coupled between the two ends of the bidirectional power supply and includes a first current path and a second current path connected in parallel. The first current path includes a first resistor unit and a battery coupled to the first resistor unit, and the second current path includes a second resistor unit. The charging test method includes: the bidirectional power supply providing a charging current to charge the battery during a charging operation, wherein the charging current is the sum of a first charging current flowing through the first current path and a second charging current flowing through the second current path; and gradually increasing the impedance of the first resistor unit while gradually decreasing the impedance of the second resistor unit, so that the current value of the first charging current gradually changes from a first current value to zero, and the current value of the second charging current gradually changes from zero to a second current value.

[0012] In some embodiments, the first current value and the second current value in the charging test method are both equal to the current value of the charging current.

[0013] This case provides a discharge test method for a battery charging and discharging system, used in a battery charging and discharging system having a bidirectional power supply and a bypass module. The bypass module is coupled between the two ends of the power supply and includes a first current path and a second current path connected in parallel. The first current path includes a first resistor unit and a battery coupled to the first resistor unit, and the second current path includes a second resistor unit. The discharge test method includes: the bidirectional power supply providing a discharge demand command to the battery; the battery responding to the discharge demand command and outputting a discharge current, wherein the discharge current is the sum of a first discharge current flowing through the first current path and a second discharge current flowing through the second current path; and gradually increasing the impedance of the first resistor unit while gradually decreasing the impedance of the second resistor unit, so that the current value of the first discharge current gradually changes from a first current value to zero, and the current value of the second discharge current gradually changes from zero to a second current value.

[0014] In some embodiments, the first current value and the second current value in the discharge test method are both equal to the current value of the discharge current.

[0015] Therefore, the main objective of this disclosure is to provide a method for battery charging and discharging that adjusts the switching timing based on the characteristics of transistors to avoid open circuits in the series charging architecture and short circuits in the battery.

Implementation Method

[0017] Please refer to Figure 1. Figure 1 is a schematic diagram of a battery charging and discharging system 10 according to an embodiment of the present invention. The battery charging and discharging system 10 includes a bypass module 110, a bypass module 120, and a bidirectional power supply 130. As shown in the embodiment in Figure 1, the bypass modules 110 and 120 are connected in series between the two ends of the bidirectional power supply 130.

[0018] The bypass module 110 includes parallel current paths P1 and P2. Current path P1 includes a resistor unit 111 and a battery 113 coupled to the resistor unit 111. Current path P2 includes a resistor unit 112.

[0019] Similarly, the bypass module 120 has parallel current paths P3 and P4. Current path P3 includes a resistor unit 121 and a battery 123 coupled to the resistor unit 121. Current path P4 includes a resistor unit 122.

[0020] In some embodiments, the battery charging and discharging system 10 is used to charge and discharge batteries 113 and 123 through bypass modules 110 and 120 and bidirectional power supply 130, so as to test the charging and discharging performance of batteries 113 and 123.

[0021] In some embodiments, the battery charging and discharging system 10 operates on batteries 113 and 123 respectively by switching the charging and discharging current transmission paths of bypass modules 110 and 120. For example, in some embodiments, the battery charging and discharging system 10 transmits charging current Ic through resistor units 111 and 121 to charge batteries 113 and 123 simultaneously. When battery 113 is fully charged while battery 123 is not fully charged, the battery charging and discharging system 10 switches the current transmission path of bypass module 110 to prevent battery 113 from being overcharged and damaged, so that the charging current Ic flows through resistor unit 112 instead of resistor unit 111. Then, battery 113 can be removed or other operations can be performed. In other words, with the above configuration, battery 123 can continue to maintain its original charging state without its charging operation being affected by battery 113 being disconnected from the system. The discharging operation of battery 113 and 123 by the battery charging and discharging system 10 is similar to the charging operation and will not be described further here.

[0022] Please refer to Figure 2. Figure 2 is a flowchart illustrating a charging test method 200 for a battery charging and discharging system according to an embodiment of this invention. The charging test method 200 will be described below with reference to steps S201 and S202 of the embodiments in Figures 3 and 4A to 4C. In some embodiments, the charging test method 200 is also used in a battery charging and discharging system 70 as shown in Figure 7.

[0023] Please refer to Figure 3. Figure 3 is a schematic diagram of a battery charging and discharging system 30 according to an embodiment of the present invention. In some embodiments, the battery charging and discharging system 30 is configured in relation to, for example, the battery charging and discharging system 10 of Figure 1.

[0024] As shown in the embodiment of Figure 3, resistor units 111 and 112 are variable resistors Rt11 and Rt12, respectively, and resistor units 121 and 122 are variable resistors Rt21 and Rt22, respectively. In some embodiments, the variable resistors Rt11, Rt12, Rt21, and Rt22 have variable impedances in response to signals S1 to S4. In some embodiments, the battery charging and discharging system 10 includes a controller (not shown) for generating signals S1 to S4 as control signals according to the operation settings (charging, discharging, etc.) of the battery on the system, so as to change the transmission path of the charging and discharging current by adjusting the impedance of the variable resistors Rt11, Rt12, and Rt21.

[0025] Please also refer to Figures 2 to 4C, wherein Figures 4A to 4C are schematic diagrams illustrating different times during a charging test of the battery charging and discharging system 30 as shown in Figure 3, according to an embodiment of the present invention.

[0026] Taking the bypass module 110 as an example, according to step S201, the bidirectional power supply 130 provides a charging current Ic to charge the battery 113 during the charging operation, wherein the charging current Ic is the sum of the charging current Ic1 flowing through the current path P1 and the charging current Ic2 flowing through the current path P2.

[0027] Specifically, as shown in Figure 4A, the variable resistor Rt11 has a low impedance (e.g., close to 0) and the variable resistor Rt12 has an extremely high impedance (e.g., close to open circuit) so that the charging current Ic flows as the charging current Ic1 through the current path P1 to charge the battery 113.

[0028] Next, when the battery 113 has been charged to a certain extent and needs to be disconnected from the charging current, according to step S202, as shown in Figure 4B, the impedance of the variable resistor Rt11 is gradually increased, while the impedance of the variable resistor Rt12 is gradually decreased, so that the current value of the charging current Ic1 gradually changes from the first current value to zero, and the current value of the charging current Ic2 gradually changes from zero to the second current value, that is, as shown in Figure 4C, the charging current Ic flows through the current path P2 as the charging current Ic2. In some embodiments where the battery 113 is fully charged and needs to be disconnected from the charging current, both the first current value and the second current value are equal to the current value of the charging current Ic.

[0029] Compared to some charging test methods that use a hard switching approach of simultaneously shutting off two current paths and then quickly turning on two current paths, the battery 113 gradually disconnects from the charging current and slowly leaves the charging circuit through the above configuration in this case. This can suppress the occurrence of a large inrush current at the moment of switching, avoid damage to the devices in the circuit, and thus improve the reliability of each device in the battery charging and discharging system.

[0030] Please refer to Figure 5. Figure 5 is a flowchart illustrating a discharge test method 500 for a battery charging and discharging system according to an embodiment of this invention. The discharge test method 500 will be described below with reference to steps S501 to S503 of the embodiments in Figures 1 and 6A to 6C. In some embodiments, the discharge test method 500 is also used in a battery charging and discharging system 70 as shown in Figure 7.

[0031] For example, according to step S501, the bidirectional power supply 130 provides a discharge demand command to the battery 113. Then, in step S502, the battery 113 responds to the discharge demand command by outputting a discharge current Idis, wherein the discharge current Idis is the sum of the discharge current Idis1 flowing through the current path P1 and the discharge current Idis2 flowing through the current path P2.

[0032] As shown in Figure 6A, the variable resistor Rt11 has low impedance and the variable resistor Rt12 has extremely high impedance, so that the discharge current Idis is the discharge current Idis1 flowing through the current path P1.

[0033] Next, when the battery 113 has discharged to a certain extent and needs to be disconnected from the discharge current, according to step S503, as shown in Figure 6B, the impedance of the variable resistor Rt11 is gradually increased, while the impedance of the variable resistor Rt12 is gradually decreased, so that the current value of the discharge current Idis1 gradually changes from the third current value to zero, and the current value of the discharge current Idis2 gradually changes from zero to the fourth current value, that is, as shown in Figure 6C, the discharge current Idis flows through the current path P2 as the discharge current Idis2. In some embodiments where the battery 113 has been completely discharged and needs to be disconnected from the discharge current, both the third current value and the fourth current value are equal to the current value of the discharge current Idis.

[0034] In other embodiments, resistor units 111 to 112 and 121 to 122 are implemented by transistors. Please refer to Figure 7. Figure 7 is a schematic diagram illustrating a battery charging and discharging system 70 according to another embodiment of the present invention. In some embodiments, the battery charging and discharging system 70 is configured in relation to, for example, the battery charging and discharging system 10 of Figure 1.

[0035] As shown in Figure 7, the resistor unit 111 in the battery charging and discharging system 70 includes transistors M11 and M12 connected in series. Resistor unit 112 includes transistors M21 and M22 connected in series. Resistor unit 121 includes transistors M31 and M32 connected in series. Resistor unit 122 includes transistors M41 and M42 connected in series. In some embodiments, transistors M11 to M12, M21 and M22, M31 and M32, and M41 and M42 are N-type metal-oxide-semiconductor field-effect transistors (MOSFETs).

[0036] In detail, the sources of transistors M11 and M12 are coupled to each other. The drain of transistor M12 is coupled to one end of battery 113. The drains of transistors M11 and M21 are coupled to each other and to bidirectional power supply 130. The sources of transistors M21 and M22 are coupled to each other. The drain of transistor M22 is coupled to the other end of battery 113 and bypass module 120. Similarly, the sources of transistors M31 and M32 are coupled to each other. The drain of transistor M32 is coupled to one end of battery 123. The drains of transistors M31 and M41 are coupled to each other and to bypass module 110. The sources of transistors M41 and M42 are coupled to each other. The drain of transistor M42 is coupled to the other end of battery 123 and bidirectional power supply 130.

[0037] The battery charging and discharging system 70 further includes drive circuits 611 to 612, 621 to 622, 631 to 632, and 641 to 642. In some embodiments, drive circuits 611 to 612 generate signals S11 to S12 in response to signals CS11 to CS12 to control transistors M11 and M12. Similarly, drive circuits 621 to 622 generate signals S21 to S22 in response to signals CS21 to CS22 to control transistors M21 and M22; drive circuits 631 to 632 generate signals S31 to S32 in response to signals CS31 to CS32 to control transistors M31 and M32; and drive circuits 641 to 642 generate signals S41 to S42 in response to signals CS41 to CS42 to control transistors M41 and M42.

[0038] In some embodiments, the battery charging and discharging system 70 includes a controller (not shown) for generating signals CS11 to CS12, CS21 to CS22, CS31 to CS32, and CS41 to CS42 as control signals based on operational settings (charging, discharging, etc.) for the battery in the system. Drive circuits 611 to 612, 621 to 622, 631 to 632, and 641 to 642 are used to delay and modulate the corresponding signals CS11 to CS12, CS21 to CS22, CS31 to CS32, and CS41 to CS42 to generate signals S11 to S12, S21 to S22, S31 to S32, and S41 to S42 with the resistance of the adjustable transistor required at a specific time, thereby changing the transmission path of the charging and discharging current in the battery charging and discharging system 70. In some embodiments, the drive circuits 611 to 612, 621 to 622, 631 to 632, and 641 to 642 may be implemented with any suitable delay circuit.

[0039] Please refer to Figures 8A to 8C. Figures 8A to 8C are schematic diagrams illustrating a charging test corresponding to the battery charging and discharging system 70 as shown in Figure 7, according to an embodiment of this invention.

[0040] Taking the bypass module 110 as an example, the bidirectional power supply 130 provides a charging current Ic to charge the battery 113 during charging operation. The charging current Ic is the sum of the charging current Ic1 flowing through the current path P1 and the charging current Ic2 flowing through the current path P2.

[0041] Specifically, as shown in Figure 8A, transistors M11 and M12 are turned on (ON) and have low impedance, while transistors M21 and M22 are turned off (OFF) and have extremely high impedance, so that the charging current Ic flows through the current path P1 as the charging current Ic1 to charge the battery 113.

[0042] Next, when the battery 113 has been charged to a certain extent and needs to be disconnected from the charging current, the conduction state of transistors M11 and M12 is adjusted by the decreasing potential of signals S11 and S12, as shown in Figure 8B. The impedance of transistors M11 and M12 gradually increases, and the current value of charging current Ic1 gradually changes from the first current value to zero. At the same time, the conduction state of transistors M21 and M22 is adjusted by the increasing potential of signals S21 and S22. The impedance of transistors M11 and M12 gradually decreases, and the current value of charging current Ic2 gradually changes from zero to the second current value, that is, as shown in Figure 8C, the charging current Ic flows through the current path P2 as the charging current Ic2. In some embodiments where the battery 113 is fully charged and needs to be disconnected from the charging current, both the first current value and the second current value are equal to the current value of charging current Ic.

[0043] Using the configuration provided in this case as described above, during the process of disconnecting the battery from the charging current, due to the impedance suppression of the two current paths of the bypass module 110, the surge current of the charging current Ic caused by the switching of transistors M11 and M12 and transistors M21 and M22 is reduced and the transient is shortened.

[0044] Conversely, some methods simultaneously shut down two paths in the charging module to switch the charging current transmission path, and use high-frequency switching speeds to achieve the purpose of switching transistors to avoid prolonged current interruption. However, this hard switching causes a very large inrush current, such as 300 amps, to appear in the charging circuit at the moment of switching. This can damage devices in the circuit, such as the power supply, the switching transistor, and the battery. Compared with the above methods, the configuration provided in this invention can suppress inrush currents to the order of 1 amp. This significantly improves the reliability of the devices in the battery charging and discharging system.

[0045] In some embodiments, after the battery 113 has undergone a charging operation and the transistors M11 to M12 in the resistor unit 111 are turned off, the charging quality of the battery 113 does not meet the standard and needs to be recharged. The battery charging and discharging system 70 can switch the transmission of charging current Ic through current path P2 to transmission of charging current Ic through current path P1 to recharge the battery 113, as shown in the embodiments of Figures 9A to 9C.

[0046] Please refer to Figures 9A to 9C. Figures 9A to 9C are schematic diagrams illustrating a charging test corresponding to the battery charging and discharging system 70 as shown in Figure 7, according to another embodiment of this case.

[0047] Initially, as shown in Figure 9A, when transistors M21 and M22 are turned on and transistors M11 and M12 are turned off, the charging current Ic flows through the current path P2 as the charging current Ic2.

[0048] Next, in the embodiments shown in Figures 9B to 9C, the impedance of transistors M21 and M22 gradually increases and the current value of charging current Ic2 gradually changes from a first current value to zero; at the same time, the impedance of transistors M11 and M12 gradually decreases and the current value of charging current Ic1 gradually changes from zero to a second current value, so that as shown in Figure 9C, charging current Ic flows through current path P1 as charging current Ic1 to recharge battery 113.

[0049] Please refer to Figures 10A to 10D. Figures 10A to 10D are schematic diagrams illustrating a discharge test corresponding to the battery charging and discharging system 70 as shown in Figure 7, according to an embodiment of this invention.

[0050] Taking the bypass module 110 as an example, the bidirectional power supply 130 provides a discharge demand command to the battery 113. Then, the battery 113 responds to the discharge demand command and outputs a discharge current Idis, where the discharge current Idis is the sum of the discharge current Idis1 flowing through the current path P1 and the discharge current Idis2 flowing through the current path P2.

[0051] As shown in Figure 10A, transistors M11 and M12 are turned on while transistors M21 and M22 are turned off, so that the discharge current Idis is the discharge current Idis1 flowing through the current path P1.

[0052] Next, when the battery 113 has been discharged to a certain extent and needs to be disconnected from the discharge current, firstly, as shown in Figures 10B to 10C, the impedance of transistors M11 and M12 is increased by gradually turning off transistors M11 and M12, so that the current value of the discharge current Idis1 gradually changes from the third current value to zero; at the same time, the impedance of transistor M22 is decreased by gradually turning on in response to the signal S22 with a rising potential, and the discharge current Idis2 flows through its parasitic diode by transistor M21 responding to the signal S21 with a low potential. Then, in Figure 10D, the current value of the discharge current Idis2 gradually changes from zero to the fourth current value by transistor M21 responding to the signal S21 with a high potential, and the discharge current Idis flows through the current path P2 as the discharge current Idis2.

[0053] Similar to the embodiment of the charging operation, using the configuration provided in this case as described above, due to the suppression of the two sets of impedances of the bypass module 110, the inrush current of the discharge current Idis caused by the switching of transistors M11 and M12 and transistors M21 and M22 is greatly reduced and this transient is shortened.

[0054] In addition, compared with the charging operation, in order to avoid short circuit of battery 113 caused by switching during discharge, transistor M21 is controlled and treated as diode operation until the commutation action of discharge current Idis is completed (Figure 10D).

[0055] In some embodiments, when the battery 113 has undergone a discharge operation and the transistors M11 to M12 in the resistor unit 111 are turned off, the discharge quality of the battery 113 does not meet the standard and needs to be recharged. The battery charging and discharging system 70 can switch from transmitting the discharge current Idis through the current path P2 to re-discharging the battery 113 and transmitting the discharge current Idis through the current path P1, as shown in the embodiments of Figures 11A to 11D.

[0056] Please refer to Figures 11A to 11D. Figures 11A to 11D are schematic diagrams illustrating a discharge test corresponding to the battery charging and discharging system 70 as shown in Figure 7, according to another embodiment of this case.

[0057] Initially, as shown in Figure 11A, when transistors M21 and M22 are turned on and transistors M11 and M12 are turned off, the discharge current Idis flows through the current path P2 as the discharge current Idis2.

[0058] Next, as shown in Figure 11B, transistor M21 is kept on and transistor M22 responds to the low-potential signal S22, causing the discharge current Idis2 to flow through its parasitic diode. Then, as shown in Figures 11C to 11D, by gradually turning on transistors M11 and M12 and lowering their impedances, the discharge current Idis1 gradually changes from zero to a third current value. Conversely, by gradually turning off transistors M21 and M22 and raising their impedances, the discharge current Idis2 gradually changes from a fourth current value to zero. The battery 113 then re-discharges and transmits the discharge current Idis through the current path P1.

[0059] The configurations shown in Figures 1 to 11D are provided for illustrative purposes. Various other embodiments of Figures 1 to 11D are within the scope of this invention. For example, in some embodiments, the battery charging and discharging system may include more than two bypass modules coupled in series with each other and have an operating mode similar to that shown in Figures 1 to 11D.

[0060] Furthermore, in some embodiments of this case, the transistor in Figure 7 may be a P-type transistor, and the battery charging and discharging system uses signals that are inversely related to those shown in Figures 8A to 11D (such as CS11 to CS12, CS21 to CS22, CS31 to CS32, CS41 to CS42 and the corresponding signals generated to the transistor) to achieve the charging and discharging operations as shown in Figures 8A to 11D.

[0061] In summary, the battery charging and discharging system and its operating method provided in this case cleverly generate two sets of impedances corresponding to the two current transmission paths by controlling the resistance change of the resistor unit in the bypass module, thereby suppressing the excessive surge current generated when switching transmission paths, further improving the reliability of each component in the battery charging and discharging system and increasing working efficiency.

[0062] The foregoing has outlined the features of several embodiments, enabling those skilled in the art to better understand the nature of one embodiment of this invention. Those skilled in the art should understand that one embodiment of this invention can be used as the basis for designing or modifying other processes and structures to achieve the same purpose and / or realize the same advantages of the embodiments described herein. Those skilled in the art should also recognize that such equivalent structures do not depart from the spirit and scope of one embodiment of this invention, and various changes, substitutions, and modifications can be made to one embodiment of this invention without departing from the spirit and scope of one embodiment of this invention. [Simplified Explanation of the Diagram]

[0016] The appearance of an embodiment of the present invention will be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that, according to standard industrial practice, the features are not drawn to scale. In fact, the dimensions of the features may be increased or decreased arbitrarily for clarity of explanation. Figure 1 is a schematic diagram of a battery charging and discharging system according to an embodiment of the present invention. Figure 2 is a flowchart of a charging test method for a battery charging and discharging system according to an embodiment of the present invention. Figure 3 is a schematic diagram of a battery charging and discharging system according to an embodiment of the present invention. Figures 4A to 4C are schematic diagrams corresponding to different times in a charging test of the battery charging and discharging system as shown in Figure 3, according to an embodiment of the present invention. Figure 5 is a flowchart of a discharging test method for a battery charging and discharging system according to an embodiment of the present invention. Figures 6A to 6C are schematic diagrams corresponding to different times in a discharging test of the battery charging and discharging system as shown in Figure 3, according to an embodiment of the present invention. Figure 7 is a schematic diagram of a battery charging and discharging system according to another embodiment of the present invention. Figures 8A to 8C are schematic diagrams illustrating different times during the charging operation of the battery charging and discharging system as shown in Figure 7, according to one embodiment of the present invention. Figures 9A to 9C are schematic diagrams illustrating different times during the charging operation of the battery charging and discharging system as shown in Figure 7, according to another embodiment of the present invention. Figures 10A to 10D are schematic diagrams illustrating different times during the discharging operation of the battery charging and discharging system as shown in Figure 7, according to one embodiment of the present invention. Figures 11A to 11D are schematic diagrams illustrating different times during the discharging operation of the battery charging and discharging system as shown in Figure 7, according to another embodiment of the present invention.

Claims

1. A battery charging and discharging system, comprising: a bidirectional power supply for providing a charging current to charge a first battery and a second battery during a charging operation; and a first bypass module and a second bypass module coupled between the two ends of the bidirectional power supply, wherein the first bypass module includes a first current path and a second current path connected in parallel, and the first current path includes a first resistor unit and the first battery coupled to the first resistor unit, the second current path includes a second resistor unit, and the second bypass module is coupled to the second battery; The charging current is the sum of a first charging current flowing through the first current path and a second charging current flowing through the second current path. The first and second transistors of the first resistor unit are controlled together and simultaneously switched from on to off, causing the impedance of the first resistor unit to gradually increase and the impedance of the second resistor unit to gradually decrease. This causes the value of the first charging current to gradually decrease from a first current value to zero, and the value of the second charging current to gradually increase from zero to a second current value. The second resistor unit includes a third and a fourth transistor. One end of the third transistor is coupled to the bidirectional power supply, and one end of the fourth transistor is coupled to the second bypass module. In a first discharge operation, the bidirectional power supply further provides a discharge demand command to the first battery. The first battery responds to the discharge demand command by outputting a discharge current, which is the sum of a first discharge current flowing through the first current path and a second discharge current flowing through the second current path. When the first discharge current is zero, the third transistor is turned on and the fourth transistor responds with a signal having a low potential, causing the second discharge current to flow through a diode in the fourth transistor; and the impedance of the first resistor unit is gradually adjusted to decrease, so that the current value of the first discharge current gradually changes from zero to a third current value; and the third transistor and the fourth transistor are gradually turned off, so that the impedance of the second resistor unit is increased, so that the current value of the second discharge current gradually changes from a fourth current value to zero.

2. The battery charging and discharging system as described in claim 1, wherein both the first current value and the second current value are equal to the current value of the charging current.

3. The battery charging and discharging system as claimed in claim 1, wherein in a second discharge operation, the impedance of the first resistor unit is adjusted to gradually increase, while the impedance of the second resistor unit is adjusted to gradually decrease, such that the current value of the first discharge current gradually changes from the third current value to zero, and the current value of the second discharge current gradually changes from zero to the fourth current value.

4. The battery charging and discharging system as described in claim 3, wherein the third current value and the fourth current value are both equal to the current value of the discharge current.

5. The battery charging and discharging system as claimed in claim 1, wherein the first resistive unit is a first variable resistor.

6. A charging and discharging test method for a battery charging and discharging system, used in a battery charging and discharging system having a bidirectional power supply and a first bypass module and a second bypass module, wherein the first bypass module and the second bypass module are coupled between the two ends of the bidirectional power supply, the first bypass module includes a first current path and a second current path connected in parallel, the first current path includes a first resistor unit and a first battery coupled to the first resistor unit, the second current path includes a second resistor unit, and the second bypass module is coupled to a second battery, the charging and discharging test method comprising: The bidirectional power supply provides a charging current to charge the first battery during a charging operation, wherein the charging current is the sum of a first charging current flowing through the first current path and a second charging current flowing through the second current path; and by controlling a first transistor and a second transistor of the first resistor unit to gradually switch from on to off simultaneously, gradually increasing the impedance of the first resistor unit and gradually decreasing the impedance of the second resistor unit, so that the current value of the first charging current gradually becomes zero, and the current value of the second charging current gradually becomes a second current value, wherein the second resistor unit includes a third transistor and a fourth transistor, one end of the third transistor is coupled to the bidirectional power supply, and one end of the fourth transistor is coupled to the second bypass module; the charging and discharging test method further includes: When the first discharge current through the first current path is zero, the third transistor is turned on and the fourth transistor is controlled to respond with a signal having a low potential, causing the second discharge current through the second current path to flow through a diode in the fourth transistor; and the impedance of the first resistor unit is gradually reduced, so that the current value of the first discharge current gradually changes from zero to a third current value; and the third transistor and the fourth transistor are gradually turned off and the impedance of the second resistor unit is increased, so that the current value of the second discharge current gradually changes from the second current value to zero.

7. The charging and discharging test method as described in claim 6, wherein the first current value and the second current value are both equal to the current value of the charging current.

8. A charging and discharging test method for a battery charging and discharging system, used in a battery charging and discharging system having a bidirectional power supply and a first bypass module and a second bypass module, the first bypass module and the second bypass module being coupled between the two ends of the bidirectional power supply, the first bypass module including a first current path and a second current path connected in parallel, the first current path including a first resistor unit and a first battery coupled to the first resistor unit, the second current path including a second resistor unit, the second bypass module being coupled to a second battery, the charging and discharging test method comprising: the bidirectional power supply providing a discharge demand command to the first battery; the first battery responding to the discharge demand command by outputting a discharge current, wherein the discharge current is the sum of a first discharge current flowing through the first current path and a second discharge current flowing through the second current path; gradually increasing the impedance of the first resistor unit while gradually decreasing the impedance of the second resistor unit, such that the current value of the first discharge current gradually changes from a first current value to zero, and the current value of the second discharge current gradually changes from zero to a second current value; The second resistor unit includes a first transistor and a second transistor. One end of the first transistor is coupled to the bidirectional power supply, and one end of the second transistor is coupled to the second bypass module. The charge-discharge test method further includes: when the first discharge current is zero, turning on the first transistor and controlling the second transistor to respond to a signal with a low potential so that the second discharge current flows through a diode in the second transistor; gradually decreasing the impedance of the first resistor unit so that the current value of the first discharge current gradually changes from zero to a third current value; and gradually turning off the first transistor and the second transistor and increasing the impedance of the second resistor unit so that the current value of the second discharge current gradually changes from the second current value to zero. The bidirectional power supply provides a charging current to charge the first battery during a charging operation, wherein the charging current is the sum of a first charging current flowing through the first current path and a second charging current flowing through the second current path; and by controlling a third transistor and a fourth transistor of the first resistor unit to gradually switch from on to off simultaneously, the impedance of the first resistor unit is gradually increased, while the impedance of the second resistor unit is gradually decreased, so that the current value of the first charging current gradually changes from a third current value to zero, and the current value of the second charging current gradually changes from zero to a fourth current value.

9. The charging and discharging test method as described in claim 8, wherein the first current value and the second current value are both equal to the current value of the discharging current.

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