Charging control circuit

Abstract

The utility model provides a charging control circuit which can be applied between a lithium battery pack and a charger and is used for charging control, and the charging control circuit comprises a pre-charging unit and a driving unit. The pre-charging unit comprises a pre-charging switch PM2, a current-limiting resistor R7 and a voltage difference loop connected to the two ends of the pre-charging switch PM2 and the two ends of the current-limiting resistor R7 in parallel, the pre-charging switch PM2 and the current-limiting resistor R7 are connected between the lithium battery pack and the charger in series, the control end of the pre-charging switch is connected in the voltage difference loop, and the control end of the pre-charging switch is connected in the voltage difference loop. The pre-charging unit is used for performing low-current charging on the lithium battery pack; and the driving unit is connected between the lithium battery pack and the charger and is used for feeding back the starting voltage provided by the lithium battery pack to the charger. According to the utility model, the problems of abnormal and unstable charging can be solved.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a charging control circuit. Background Technology

[0002] In energy storage products, lithium-ion batteries may over-discharge under conditions such as prolonged storage and excessive use, causing the voltage to drop below the charger's recognition threshold. Currently, many chargers on the market use software-controlled circuits, such as microcontrollers or relays for switching control. These typically consist of a main control IC, multiple MOSFETs, and several resistors. The main control IC is prone to malfunction due to undervoltage, causing both charging and discharging MOSFETs to shut down. After connecting the charger, the MOSFETs are turned on by adjusting the resistance value of a specific resistor, forming a dedicated charging circuit to charge the battery. Once the lithium battery pack voltage reaches the main control IC's normal operating voltage, the MOSFETs turn off, and the system resumes normal charging. This circuit design is relatively complex, requiring precise adjustment of the resistor values ​​to control the MOSFET turn-on voltage. Improper resistor parameter selection or unstable MOSFET performance can lead to abnormal charging or even damage to the MOSFETs and the lithium battery pack. Utility Model Content

[0003] The main objective of this invention is to provide a charging control circuit to solve the problems in the prior art.

[0004] To achieve the above and other related objectives, this utility model provides a charging control circuit that can be applied between a lithium battery pack and a charger for charging control. The charging control circuit includes a pre-charging unit and a driving unit.

[0005] The pre-charging unit includes a pre-charging switch PM2, a current-limiting resistor R7, and a differential voltage circuit connected in parallel across the pre-charging switch PM2 and the current-limiting resistor R7. The pre-charging switch PM2 and the current-limiting resistor R7 are connected in series between the lithium battery pack and the charger. The control terminal of the pre-charging switch is connected in the differential voltage circuit. The pre-charging unit is used to charge the lithium battery pack with low current.

[0006] A drive unit is connected between the lithium battery pack and the charger, and is used to feed back the startup voltage provided by the lithium battery pack to the charger.

[0007] As a preferred embodiment, the differential pressure circuit includes a Zener diode ZD2, resistors R5 and R6. The cathode of the Zener diode ZD2 is connected between the precharge switch PM2 and the lithium battery pack, the anode of the Zener diode ZD2 is connected to resistor R5, the other end of resistor R5 is connected to resistor R6, the other end of resistor R6 is connected to the charger, and the control terminal of the precharge switch PM2 is connected between the Zener diode ZD2 and resistor R5. The precharge switch PM2 is a P-type AC field-effect transistor.

[0008] As a preferred embodiment, the resistor R6 is connected to the negative terminal P- of the charger, and a diode D1 is also connected to the positive terminal of the diode D1.

[0009] As a preferred embodiment, the drive unit includes a first drive circuit, the first drive circuit including a pre-charge switch PM1, the pre-charge switch PM1 being connected between the lithium battery pack and the feedback terminal of the charger, and the control terminal of the pre-charge switch PM1 being connected between the lithium battery pack and the pre-charge switch PM2.

[0010] As a preferred embodiment, the drive unit further includes a second drive circuit, the second drive circuit including a pre-charge switch Q1, the pre-charge switch Q1 being connected between the pre-charge switch PM2, the pre-charge switch PM1 and the lithium battery pack.

[0011] As a preferred embodiment, the first drive circuit further includes resistors R3 and R4. The pre-charge switch PM1 is a P-type AC field-effect transistor. The source of the pre-charge switch PM1 is connected between the positive terminal B+ of the lithium battery pack and the positive terminal P+ of the charger. The drain of the pre-charge switch PM1 is connected to the feedback terminal of the charger. The gate of the pre-charge switch PM1 is connected between resistors R3 and R4. The other end of resistor R3 is connected between the positive terminal B+ of the lithium battery pack and the positive terminal P+ of the charger. The other end of resistor R4 is connected to the pre-charge switch Q1.

[0012] As a preferred embodiment, the second drive circuit further includes resistors R1 and R2. The pre-charge switch Q1 is a PNP transistor. The collector of the pre-charge switch Q1 is connected to the resistor R4. The emitter of the pre-charge switch Q1 is connected between the negative terminal B- of the lithium battery pack and the source of the pre-charge switch PM2. The base of the pre-charge switch Q1 is connected between the resistors R1 and R2. The other end of the resistor R1 is connected between the positive terminal B+ of the lithium battery pack and the positive terminal P+ of the charger. The other end of the resistor R2 is connected between the negative terminal B- of the lithium battery pack and the source of the pre-charge switch PM2.

[0013] As a preferred embodiment, a capacitor C is connected in parallel across the two ends of the resistor R2.

[0014] The charging control circuit of this invention includes a pre-charging unit and a driving unit. The pre-charging unit includes a pre-charging switch PM2, a current-limiting resistor R7, and a differential voltage circuit connected in parallel across the pre-charging switch PM2 and the current-limiting resistor R7. When the lithium battery pack and the charger are connected through this charging control circuit, a voltage difference is formed between the charger and the lithium battery pack. This voltage difference creates a low current in the differential voltage circuit, which can turn on the pre-charging switch PM2, thereby opening the circuit between the lithium battery pack and the charger. The charger current flows through the current-limiting resistor R7 to achieve low-current charging of the lithium battery pack. The driving unit is connected between the lithium battery pack and the charger and can feed back the voltage of the charged lithium battery pack to the charger. Once the lithium battery pack is slowly charged to the operating voltage required by the main control IC in the charger, the main control IC can control high-current charging. This charging control circuit can provide low-current charging before normal charging when the lithium battery pack has zero voltage, avoiding the charging abnormalities and instability that can easily occur when directly supplying high voltage to the main control IC of the charger. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a circuit diagram of a charging control circuit provided in one embodiment of the present invention. Detailed Implementation

[0017] In the following description, specific details such as particular system structures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the present invention. However, those skilled in the art will understand that the present invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

[0018] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0019] It should also be understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0020] Please refer to Figure 1 The charging control circuit provided in one embodiment of the present invention can be applied between a lithium battery pack and a charger for charging control. The charging control circuit includes a pre-charging unit and a driving unit.

[0021] The pre-charging unit includes a pre-charging switch PM2, a current-limiting resistor R7, and a differential voltage circuit connected in parallel across the pre-charging switch PM2 and the current-limiting resistor R7. The pre-charging switch PM2 and the current-limiting resistor R7 are connected in series between the lithium battery pack and the charger. The control terminal of the pre-charging switch is connected in the differential voltage circuit. The pre-charging unit is used to charge the lithium battery pack with low current.

[0022] A drive unit is connected between the lithium battery pack and the charger, and is used to feed back the startup voltage provided by the lithium battery pack to the charger.

[0023] The charging control circuit of this invention includes a pre-charging unit and a driving unit. The pre-charging unit includes a pre-charging switch PM2, a current-limiting resistor R7, and a differential voltage circuit connected in parallel across the pre-charging switch PM2 and the current-limiting resistor R7. When the lithium battery pack and the charger are connected through this charging control circuit, a voltage difference is formed between the charger and the lithium battery pack. This voltage difference creates a low current in the differential voltage circuit, which can turn on the pre-charging switch PM2, thereby opening the circuit between the lithium battery pack and the charger. The charger current flows through the current-limiting resistor R7 to achieve low-current charging of the lithium battery pack. The driving unit is connected between the lithium battery pack and the charger and can feed back the voltage of the charged lithium battery pack to the charger. Once the lithium battery pack is slowly charged to the operating voltage required by the main control IC in the charger, the main control IC can control high-current charging. This charging control circuit can provide low-current charging before normal charging when the lithium battery pack has zero voltage, avoiding the charging abnormalities and instability that can easily occur when directly supplying high voltage to the main control IC of the charger.

[0024] Specifically, the differential pressure circuit of this utility model includes a Zener diode ZD2, a resistor R5, and a resistor R6. The negative terminal of the Zener diode ZD2 is connected between the precharge switch PM2 and the lithium battery pack. The positive terminal of the Zener diode ZD2 is connected to the resistor R5. The other end of the resistor R5 is connected to the resistor R6. The other end of the resistor R6 is connected to the charger. The control terminal of the precharge switch PM2 is connected between the Zener diode ZD2 and the resistor R5. The precharge switch PM2 is a P-type AC field-effect transistor.

[0025] Understandably, when the charging control circuit of this utility model is connected between the lithium battery pack and the charger, the lithium battery pack may experience over-discharge due to long-term storage or excessive use, causing its voltage to drop below the charger's recognition threshold. The charger voltage is typically the voltage of a fully charged lithium battery pack. The voltage difference between the positive terminal B+ and the negative terminal B- of the lithium battery pack is 0V, while the voltage difference between the positive terminal P+ and the negative terminal P- of the charger is the full-charge voltage. Therefore, the voltage difference between the negative terminal P- of the charger and the negative terminal B- of the battery pack is the full-charge voltage. The Zener diode ZD2 breaks down in reverse, making the circuit from the negative terminal B- of the lithium battery pack, the Zener diode ZD2, resistor R5, resistor R6 to the negative terminal P- of the charger conduct. This causes the control terminal of the pre-charge switch PM2 to be at a low level, thereby turning on the pre-charge switch PM2. When the pre-charge switch PM2 is turned on, the circuit from the negative terminal B- of the lithium battery pack, the pre-charge switch PM2, the current-limiting resistor R7 to the charger P- is connected. At this time, the charging current in this circuit is the full-charge voltage provided by the charger minus the voltage difference across the lithium battery pack, divided by the resistance value of the current-limiting resistor R7. Therefore, the charging current for pre-charging the lithium battery pack can be adjusted by adjusting the resistance value of the current-limiting resistor R7. This charging current is smaller than the voltage and current supplied directly to the main control IC of the charger, which is less likely to cause excessive power consumption and less likely to damage the components in the circuit, thus improving charging safety.

[0026] Furthermore, the resistor R6 is connected to the negative terminal P- of the charger, and a diode D1 is connected to the positive terminal of the diode D1.

[0027] Understandably, diode D1 can effectively prevent the lithium battery pack from discharging to the charger through the negative terminal B- and the charging control circuit of this invention, thereby further improving charging safety.

[0028] Furthermore, the drive unit includes a first drive circuit, the first drive circuit includes a pre-charge switch PM1, the pre-charge switch PM1 is connected between the lithium battery pack and the feedback terminal of the charger, and the control terminal of the pre-charge switch PM1 is connected between the lithium battery pack and the pre-charge switch PM2.

[0029] Furthermore, the drive unit also includes a second drive circuit, which includes a pre-charge switch Q1 connected between the pre-charge switch PM2, the pre-charge switch PM1, and the lithium battery pack.

[0030] Furthermore, the first drive circuit also includes resistors R3 and R4. The pre-charge switch PM1 is a P-type AC field-effect transistor. The source of the pre-charge switch PM1 is connected between the positive terminal B+ of the lithium battery pack and the positive terminal P+ of the charger. The drain of the pre-charge switch PM1 is connected to the feedback terminal of the charger. The gate of the pre-charge switch PM1 is connected between resistors R3 and R4. The other end of resistor R3 is connected between the positive terminal B+ of the lithium battery pack and the positive terminal P+ of the charger. The other end of resistor R4 is connected to the pre-charge switch Q1.

[0031] Furthermore, the second drive circuit also includes resistors R1 and R2. The pre-charge switch Q1 is a PNP transistor. The collector of the pre-charge switch Q1 is connected to the resistor R4. The emitter of the pre-charge switch Q1 is connected between the negative terminal B- of the lithium battery pack and the source of the pre-charge switch PM2. The base of the pre-charge switch Q1 is connected between the resistors R1 and R2. The other end of the resistor R1 is connected between the positive terminal B+ of the lithium battery pack and the positive terminal P+ of the charger. The other end of the resistor R2 is connected between the negative terminal B- of the lithium battery pack and the source of the pre-charge switch PM2.

[0032] It's important to understand that when the pre-charge switch PM2 is turned on at the negative terminal B- of the lithium battery pack and the negative terminal P- of the charger, the lithium battery pack voltage will slowly rise. Once it reaches a certain level, the voltage of the lithium battery pack will meet the operating voltage requirements of the charger's main control IC. At this point, the voltage drop across resistor R2 satisfies the condition for turning on the pre-charge switch Q1. After Q1 is turned on, the circuit with resistors R3 and R4 is completed, making the gate of pre-charge switch PM1 low. This causes PM1 to turn on, which in turn opens the circuit from the positive terminal B+ of the lithium battery pack to the charger feedback terminal CHG. The lithium battery pack then supplies power to the charger's main control IC, which controls the high-current charging. Additionally, the conduction of pre-charge switch PM1 creates a circuit from its drain to the charger feedback terminal CHG, providing a high level to the gate of pre-charge switch PM2, causing PM2 to turn off and continue charging.

[0033] Furthermore, a capacitor C is connected in parallel across the two ends of the resistor R2, and capacitor C is a filter capacitor.

[0034] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be included within the protection scope of this utility model.

Claims

1. A charging control circuit, applicable between a lithium battery pack and a charger for charging control, characterized in that, The charging control circuit includes a pre-charging unit and a driving unit; The pre-charging unit includes a pre-charging switch PM2, a current-limiting resistor R7, and a differential voltage circuit connected in parallel across the pre-charging switch PM2 and the current-limiting resistor R7. The pre-charging switch PM2 and the current-limiting resistor R7 are connected in series between the lithium battery pack and the charger. The control terminal of the pre-charging switch is connected in the differential voltage circuit. The pre-charging unit is used to charge the lithium battery pack with low current. A drive unit is connected between the lithium battery pack and the charger, and is used to feed back the startup voltage provided by the lithium battery pack to the charger.

2. The charging control circuit according to claim 1, characterized in that, The differential pressure circuit includes a Zener diode ZD2, resistors R5 and R6. The cathode of the Zener diode ZD2 is connected between the precharge switch PM2 and the lithium battery pack. The anode of the Zener diode ZD2 is connected to resistor R5. The other end of resistor R5 is connected to resistor R6. The other end of resistor R6 is connected to the charger. The control terminal of the precharge switch PM2 is connected between the Zener diode ZD2 and resistor R5. The precharge switch PM2 is a P-type AC field-effect transistor.

3. The charging control circuit according to claim 2, characterized in that, The resistor R6 is connected to the negative terminal P- of the charger, and a diode D1 is also connected to the positive terminal of the diode D1.

4. The charging control circuit according to claim 3, characterized in that, The drive unit includes a first drive circuit, which includes a pre-charge switch PM1. The pre-charge switch PM1 is connected between the lithium battery pack and the feedback terminal of the charger, and the control terminal of the pre-charge switch PM1 is connected between the lithium battery pack and the pre-charge switch PM2.

5. The charging control circuit according to claim 4, characterized in that, The drive unit further includes a second drive circuit, which includes a pre-charge switch Q1 connected between the pre-charge switch PM2, the pre-charge switch PM1, and the lithium battery pack.

6. The charging control circuit according to claim 5, characterized in that, The first drive circuit also includes resistors R3 and R4. The pre-charge switch PM1 is a P-type AC field-effect transistor. The source of the pre-charge switch PM1 is connected between the positive terminal B+ of the lithium battery pack and the positive terminal P+ of the charger. The drain of the pre-charge switch PM1 is connected to the feedback terminal of the charger. The gate of the pre-charge switch PM1 is connected between resistors R3 and R4. The other end of resistor R3 is connected between the positive terminal B+ of the lithium battery pack and the positive terminal P+ of the charger. The other end of resistor R4 is connected to the pre-charge switch Q1.

7. The charging control circuit according to claim 6, characterized in that, The second drive circuit also includes resistors R1 and R2. The pre-charge switch Q1 is a PNP transistor. The collector of the pre-charge switch Q1 is connected to the resistor R4. The emitter of the pre-charge switch Q1 is connected between the negative terminal B- of the lithium battery pack and the source of the pre-charge switch PM2. The base of the pre-charge switch Q1 is connected between the resistors R1 and R2. The other end of the resistor R1 is connected between the positive terminal B+ of the lithium battery pack and the positive terminal P+ of the charger. The other end of the resistor R2 is connected between the negative terminal B- of the lithium battery pack and the source of the pre-charge switch PM2.

8. The charging control circuit according to claim 7, characterized in that, A capacitor C is connected in parallel across the two ends of the resistor R2.

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