Control method and control system for preventing overlarge impact current when charger is started
By detecting the battery voltage before the charger starts and adjusting the feedback loop reference voltage to limit the charging current, the problem of excessive impact current when the charger starts is solved, and an efficient and low-cost charging process is achieved.
Patent Information
- Application Number
- CN202510077147.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-17
- Publication Date
- 2025-04-25
AI Technical Summary
Existing chargers are prone to shock currents when starting up, which may damage the charger circuitry and connection equipment, and existing current limiting loop methods may reduce charging efficiency and increase costs.
Before turning on the MOS tube of the charging circuit, the output current of the charger is limited by detecting the battery voltage and adjusting the reference voltage of the voltage feedback loop and the current feedback loop, thereby suppressing the impact current and gradually returning to the rated current after the charging current stabilizes.
It effectively reduces the impact current at the start of the charger, ensures charging efficiency, reduces the impact on existing circuits, and reduces costs.
Smart Images
Figure CN119891460A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of chargers, and in particular to a control method and a control system for preventing excessive surge current when a charger is started. Background Art
[0002] When the charger is charging the battery, it charges the battery through the charging circuit. The charging circuit is equipped with a MOS tube, a voltage feedback loop and a current feedback loop. When starting, the MOS tube is turned on, the charging circuit is turned on, and the charger charges the battery through the charging circuit. The entire charging process is generally divided into a constant current charging stage and a constant voltage charging stage: at the beginning of charging, the battery voltage is low, and the current loop control circuit outputs a set constant current to charge the battery. At this time, the output voltage of the voltage loop is lower than the battery voltage, and the voltage loop does not participate in the control. In the constant voltage charging stage: as the battery voltage increases, when the set constant voltage value is reached, the voltage loop begins to work, gradually increasing its control strength to maintain the output voltage at a constant value, and the control strength of the current loop gradually weakens, and the output current decreases accordingly. Finally, the circuit enters a constant voltage charging state, and the output current gradually decreases until the battery is fully charged.
[0003] When the charger is charging the battery, the inrush current at startup has always been a concern. The inrush current may not only damage the charger's own circuits and components, but may also have an adverse effect on the connected battery or other devices. The generation of this inrush current mainly comes from the charger's rapid adjustment of voltage and current at startup, as well as the transient response of components such as inductors and capacitors that may exist in the circuit.
[0004] To solve this problem, there are currently a variety of hardware solutions. However, these existing technologies still have certain shortcomings and limitations. For example, some chargers limit the current size at startup by adding a current limiting circuit, but this method may reduce charging efficiency, increase power consumption and cost, and even lead to insufficient charging in some cases. Summary of the invention
[0005] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is: how to provide a control method and control system for preventing excessive inrush current when the charger is started while ensuring charging efficiency and effectively reducing the impact on the existing circuit and at a low cost.
[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: A control method for preventing excessive inrush current when a charger is started. Before turning on the MOS tube of the charging circuit, the charging circuit is controlled according to a set method to limit the inrush current when the charger is started. Then the MOS tube is turned on and the charging current is gradually increased to the rated current according to the set method.
[0007] Preferably, the setting method includes: before turning on the MOS tube of the charging circuit, detecting the battery voltage so that the output voltage of the charger is greater than the battery voltage, and the difference between the output voltage of the charger and the battery voltage is less than a set value.
[0008] Preferably, the setting method also includes: before turning on the MOS tube of the charging circuit, setting the reference voltage of the current feedback loop at this time to a first reference voltage, and when the charging current is the rated current, the reference voltage of the current feedback loop is a second reference voltage, and the first reference voltage is less than the second reference voltage.
[0009] Preferably, the method comprises the following steps: Step 1) Connect the charger to the battery; Step 2) Turn off the MOS tube of the charging circuit; Step 3) Detect the current voltage of the battery; Step 4) Whether the charger output voltage is greater than the battery voltage, and the difference between the charger output voltage and the battery voltage is less than the set value, if yes, execute step 6), if not, execute step 5); Step 5) Adjust the output voltage of the charger and then return to step 4); Step 6) setting the reference voltage of the current feedback loop at this time to be the first reference voltage, and when the charging current is the rated current, the reference voltage of the current feedback loop to be the second reference voltage, so that the first reference voltage is less than the second reference voltage; Step 7) Turn on the MOS tube of the charging circuit; Step 8) Delay setting time; Step 9) Gradually increase the charging current to the rated current according to the setting method.
[0010] A control system for implementing the above control method for preventing excessive inrush current when the charger is started, comprising a microcontroller and a charging circuit, wherein the charging circuit comprises a current feedback loop, a voltage feedback loop and a MOS tube; The microcontroller is electrically connected to the output end of the charger, the battery, the voltage feedback loop and the current feedback loop respectively. The microcontroller is used to collect the output voltage, output current and battery voltage of the charger, and before turning on the MOS tube of the charging circuit, the microcontroller adjusts the reference voltage of the voltage feedback loop according to the collected output voltage and battery voltage of the charger, so that the output voltage of the charger is greater than the battery voltage, and the difference between the output voltage of the charger and the battery voltage is less than the set value; before turning on the MOS tube of the charging circuit, the microcontroller adjusts the reference voltage of the current feedback loop at this time to a first reference voltage, and makes the first reference voltage less than a second reference voltage, and the second reference voltage is the reference voltage of the current feedback loop when the charging current is the rated current.
[0011] Preferably, it further includes a photocoupler U1, a transformer and an LLC resonant circuit, the primary input winding of the transformer is used to be connected to the charger end, the secondary output winding of the transformer is used to be connected to the battery end, the LLC resonant circuit is connected to the primary input winding of the transformer, the gain change of the LLC resonant circuit causes the output voltage of the transformer to change, the input end of the photocoupler U1 is respectively connected to the voltage feedback loop and the current feedback loop, and the output end of the photocoupler U1 is connected to the LLC resonant circuit, so that the output change of the voltage feedback loop and the current feedback loop causes the change of the output of the photocoupler U1, and the change of the output of the photocoupler U1 causes the gain change of the LLC resonant circuit.
[0012] Preferably, the current feedback loop includes an operational comparator U2, the non-inverting input terminal of the operational comparator U2 is connected to the microcontroller, and the output terminal of the operational comparator U2 is connected to the photocoupler U1. Before turning on the MOS tube of the charging circuit, the microcontroller adjusts the first reference voltage of the non-inverting input terminal of the operational comparator U2 to be lower than the second reference voltage, so that the operational comparator U2 outputs a low level. When the operational comparator U2 outputs a low level, the output terminal voltage of the photocoupler U1 is reduced, and the gain of the LLC resonant circuit is reduced, so that the charging current of the charger is reduced to below the rated value.
[0013] Preferably, the voltage feedback loop includes a voltage regulator Z1, a cathode of the voltage regulator Z1 is connected to the photocoupler U1, an anode of the voltage regulator Z1 is grounded, a control electrode of the voltage regulator Z1 is connected to the microcontroller, and before turning on the MOS tube of the charging circuit, the microcontroller detects the battery voltage and adjusts the control electrode voltage of the voltage regulator Z1 to turn on the voltage regulator Z1, increase the current flowing through the photocoupler, reduce the output voltage of the photocoupler, reduce the gain of the LLC resonant circuit, and reduce the output voltage of the charger until the difference between the output voltage of the charger and the battery voltage is less than a set value.
[0014] Preferably, after the MOS tube of the charging circuit is turned on and during constant current charging, the operational comparator U2 outputs a low level when the output current of the charger is greater than the rated current. When the operational comparator U2 outputs a low level, the output voltage of the photoelectric coupler U1 is reduced, the gain of the LLC resonant circuit is reduced, and the output current of the charger is reduced and finally stabilized at the rated current; the operational comparator U2 outputs a high level when the output current of the charger is less than the rated current. When the operational comparator U2 outputs a high level, the output voltage of the photoelectric coupler U1 is increased, the gain of the LLC resonant circuit is increased, and the output current of the charger is increased and finally stabilized at the rated current.
[0015] Preferably, after the MOS tube of the charging circuit is turned on and during constant voltage charging, when the output voltage of the charger is greater than the rated voltage, the control electrode voltage of the voltage regulator Z1 is greater than the reference voltage of the voltage regulator Z1, so that the voltage regulator Z1 is turned on, the current flowing through the photocoupler U1 increases, the output voltage of the photocoupler U1 decreases, the gain of the LLC resonant circuit decreases, and the output voltage of the charger decreases until the output voltage of the charger stabilizes at the rated voltage; when the output voltage of the charger is less than the rated voltage, the control electrode voltage of the voltage regulator Z1 is less than the reference voltage of the voltage regulator Z1, so that the voltage regulator Z1 is turned off, the current flowing through the photocoupler U1 decreases, the output voltage of the photocoupler U1 increases, the gain of the LLC resonant circuit increases, and the output voltage of the charger increases until the output voltage of the charger stabilizes at the rated voltage.
[0016] Compared with the prior art, the present invention has the following advantages: 1. Before turning on the MOS tube of the charging circuit, the present invention first controls the circuit according to the setting method, limits the system output capacity to suppress the impact current by lowering the reference points of the voltage feedback loop and the current feedback loop, and at the same time, by detecting the battery voltage, makes the output voltage of the charger slightly greater than the battery voltage, thereby limiting the output of the charging current. In this way, when the MOS tube is turned on to start charging, the charging current is limited to achieve the purpose of suppressing the impact current. When the charging current is stable, the reference points of the voltage feedback loop and the current feedback loop are gradually increased, and the charging current is gradually restored to the rated current. Therefore, this solution only needs to add a set of soft start logic on the basis of the existing circuit, and the output current is controlled to rise slowly by setting the voltage difference threshold and controlling the current feedback, which reduces the impact on the existing circuit and has low cost. At the same time, this solution still charges at the rated current after startup, and has high charging efficiency.
[0017] 2. Based on the existing circuit, this solution adds software control technology to suppress the impact current during the charger startup process, which can effectively reduce the impact current during startup while ensuring charging efficiency and safety, and minimize the additional impact on existing circuits and components. This method should have high practicality and economy, provide more reliable technical support for optimizing the startup performance of the charger, improve product safety, and extend product service life.
[0018] 3. When the output end is unloaded (battery not connected), this solution can control the output voltage to be lower than the battery voltage, meeting the requirements of IEC60335-1 and meeting export requirements. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a flow chart of a control method for preventing excessive inrush current when the charger is started according to the present invention; Figure 2 is a system block diagram of the control system of the present invention; Figure 3 is a circuit schematic diagram of a voltage feedback loop in the control system of the present invention; Figure 4 It is a circuit schematic diagram of the current feedback loop in the control system of the present invention. DETAILED DESCRIPTION
[0020] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.
[0021] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0022] First, this solution provides a control method to prevent excessive inrush current when the charger is started. Before turning on the MOS tube of the charging circuit, the charging circuit is controlled according to a set method to limit the inrush current when the charger is started. Then the MOS tube is turned on and the charging current is gradually increased to the rated current according to the set method.
[0023] The setting method includes: before turning on the MOS tube of the charging circuit, detecting the battery voltage so that the output voltage of the charger is greater than the battery voltage, and the difference between the output voltage of the charger and the battery voltage is less than the set value. Before turning on the MOS tube of the charging circuit, setting the reference voltage of the current feedback loop at this time to the first reference voltage, when the charging current is the rated current, the reference voltage of the current feedback loop is the second reference voltage, and the first reference voltage is less than the second reference voltage.
[0024] Before turning on the MOS tube of the charging circuit, the present invention first controls the circuit according to the setting method, limits the system output capacity to suppress the impact current by lowering the reference points of the voltage feedback loop and the current feedback loop, and at the same time, by detecting the battery voltage, makes the output voltage of the charger slightly greater than the battery voltage, thereby limiting the output of the charging current, so that when the MOS tube is turned on to start charging, the charging current is limited to achieve the purpose of suppressing the impact current. When the charging current is stable, the reference points of the voltage feedback loop and the current feedback loop are gradually increased, and the charging current is gradually restored to the rated current. Therefore, this solution only needs to add a set of soft start logic on the basis of the existing circuit, and the output current is controlled to rise slowly by setting the voltage difference threshold and controlling the current feedback, which reduces the impact on the existing circuit and has low cost. At the same time, this solution still charges at the rated current after starting, and has high charging efficiency.
[0025] Specifically, as attached Figure 1 As shown, the method comprises the following steps: Step 1) System startup; Step 2) After detecting that the charger is connected to the battery, proceed to step 3); Step 3) Handshake with the battery; Step 4) Check whether the handshake is successful. If yes, proceed to step 5. If not, proceed to step 3); Step 5) Turn off the MOS tube of the charging circuit; Step 6) Detect the current voltage of the battery; Step 7) Whether the charger output voltage is greater than the battery voltage, and the difference between the charger output voltage and the battery voltage is less than the set value, if yes, execute step 9), if not, execute step 8); Step 5) Adjust the output voltage of the charger, and then return to step 7); Step 9) setting the reference voltage of the current feedback loop at this time to be the first reference voltage, and when the charging current is the rated current, the reference voltage of the current feedback loop to be the second reference voltage, so that the first reference voltage is less than the second reference voltage; Step 10) Turn on the MOS tube of the charging circuit; Step 11) Delay setting time; Step 12) Gradually increase the charging current to the rated current according to the setting method. The setting method is to gradually increase the current control point within a certain period of time until the rated current is reached.
[0026] In addition, in this specific embodiment, a control system is provided to implement the control method for preventing the inrush current from being too large when the charger is started. Figure 2 As shown, it includes a microcontroller and a charging circuit, and the charging circuit includes a current feedback loop, a voltage feedback loop, a MOS tube, a photocoupler U1, a transformer and an LLC resonant circuit; The primary input winding of the transformer is used as an AC input terminal for connecting to the charger terminal, the secondary output winding of the transformer is used as a DC output terminal for connecting to the battery terminal, the LLC resonant circuit is connected to the primary input winding of the transformer, and the gain change of the LLC resonant circuit causes the output voltage of the transformer to change. The input terminal of the photocoupler U1 is respectively connected to the voltage feedback loop and the current feedback loop, and the output terminal of the photocoupler U1 is connected to the LLC resonant circuit, so that the output change of the voltage feedback loop and the current feedback loop causes the change of the output of the photocoupler U1, and the change of the output of the photocoupler U1 causes the gain change of the LLC resonant circuit.
[0027] The microcontroller is electrically connected to the output end of the charger, the battery, the voltage feedback loop and the current feedback loop respectively. The microcontroller is used to collect the output voltage, output current and battery voltage of the charger, and before turning on the MOS tube of the charging circuit, the microcontroller adjusts the reference voltage of the voltage feedback loop according to the collected output voltage and battery voltage of the charger, so that the output voltage of the charger is greater than the battery voltage, and the difference between the output voltage of the charger and the battery voltage is less than the set value; before turning on the MOS tube of the charging circuit, the microcontroller adjusts the reference voltage of the current feedback loop at this time to a first reference voltage, and makes the first reference voltage less than a second reference voltage. The second reference voltage is the reference voltage of the current feedback loop when the charging current is the rated current.
[0028] As attached Figure 4As shown, specifically, the current feedback loop includes an operational comparator U2, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, and a capacitor C11. The non-inverting input terminal (pin 3) of the operational comparator U2 is connected to the microcontroller, and the output terminal (pin 1) of the operational comparator U2 is connected to the photocoupler U1. Before turning on the MOS tube of the charging circuit, the microcontroller adjusts the first reference voltage of the non-inverting input terminal of the operational comparator U2 to be lower than the second reference voltage, so that the operational comparator U2 outputs a low level. When the operational comparator U2 outputs a low level, the output terminal voltage of the photocoupler U1 is reduced, and the gain of the LLC resonant circuit is reduced, so that the charging current of the charger is reduced to below the rated value. After the MOS tube of the charging circuit is turned on and during constant current charging, the operational comparator U2 outputs a low level when the output current of the charger is greater than the rated current. When the operational comparator U2 outputs a low level, the output voltage of the photocoupler U1 is reduced, the gain of the LLC resonant circuit is reduced, and the output current of the charger is reduced and finally stabilized at the rated current; the operational comparator U2 outputs a high level when the output current of the charger is less than the rated current. When the operational comparator U2 outputs a high level, the output voltage of the photocoupler U1 is increased, the gain of the LLC resonant circuit is increased, and the output current of the charger is increased and finally stabilized at the rated current.
[0029] For example, if the rated output is set to 4A, if the output current is less than 4A, the voltage at the non-inverting input terminal (pin 3) of the operational comparator U2 is greater than the voltage at the inverting input terminal (pin 2) of the operational comparator U2 through feedback from the sampling resistor, and the output terminal (pin 1) of the operational comparator U2 is high. The current flowing through the optocoupler U1 decreases, and the current on the other side decreases. The voltage at the FB pin of the optocoupler U1 increases, resulting in a decrease in the resonant frequency of the LLC resonant circuit, an increase in gain, and an increase in output, ultimately stabilizing the output current to 4A.
[0030] Specifically, as attached Figure 3As shown, the voltage feedback loop includes a voltage regulator Z1, a resistor 3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, and a diode D1. The cathode of the voltage regulator Z1 is connected to the photocoupler U1, the anode of the voltage regulator Z1 is grounded, and the control electrode of the voltage regulator Z1 is connected to the microcontroller. Before turning on the MOS tube of the charging circuit, the microcontroller detects the battery voltage and adjusts the control electrode voltage of the voltage regulator Z1 to turn on the voltage regulator Z1, increase the current flowing through the photocoupler, reduce the output voltage of the photocoupler, reduce the gain of the LLC resonant circuit, and reduce the output voltage of the charger until the difference between the output voltage of the charger and the battery voltage is less than the set value.
[0031] Specifically, after the MOS tube of the charging circuit is turned on and during constant voltage charging, when the output voltage of the charger is greater than the rated voltage, the control electrode voltage of the voltage regulator Z1 is greater than the reference voltage of the voltage regulator Z1, so that the voltage regulator Z1 is turned on, the current flowing through the photocoupler U1 increases, the output voltage of the photocoupler U1 decreases, the gain of the LLC resonant circuit decreases, and the output voltage of the charger decreases until the output voltage of the charger stabilizes at the rated voltage; when the output voltage of the charger is less than the rated voltage, the control electrode voltage of the voltage regulator Z1 is less than the reference voltage of the voltage regulator Z1, so that the voltage regulator Z1 is turned off, the current flowing through the photocoupler U1 decreases, the output voltage of the photocoupler U1 increases, the gain of the LLC resonant circuit increases, and the output voltage of the charger increases until the output voltage of the charger stabilizes at the rated voltage.
[0032] For example, the reference voltage of the voltage regulator Z1 is 2.5V. If the output is set to 54V, if the output voltage is greater than 54V, due to the voltage divider feedback, pin 1 of the voltage regulator Z1 will be greater than 2.5V. At this time, the voltage regulator Z1 will be turned on, and the current flowing through the optocoupler U1 will increase. The current on the other side will increase, and the voltage on the FB pin of the optocoupler U1 will decrease, causing the resonant frequency of the LLC resonant circuit to increase, the gain to decrease, and the output to decrease, ultimately stabilizing the output voltage to 54V.
[0033] Based on the existing circuit, this solution adds software control technology to suppress the impact current during the charger startup process. It can effectively reduce the impact current during startup while ensuring charging efficiency and safety, and minimize the additional impact on existing circuits and components. This method should have high practicality and economy, provide more reliable technical support for optimizing the startup performance of the charger, improve product safety, and extend product life. When the output end is unloaded (battery not connected), this solution can control the output voltage to be lower than the battery voltage, meet the requirements of IEC60335-1, and meet export requirements.
[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.
Claims
1. A control method for preventing excessive inrush current when a charger is started, characterized in that: Before turning on the MOS tube of the charging circuit, the charging circuit is controlled according to the setting method to limit the impact current when the charger is started, and then the MOS tube is turned on, and the charging current is gradually increased to the rated current according to the setting method.
2. The control method for preventing excessive inrush current when the charger is started according to claim 1, characterized in that: The setting method includes: before turning on the MOS tube of the charging circuit, detecting the battery voltage so that the output voltage of the charger is greater than the battery voltage, and the difference between the output voltage of the charger and the battery voltage is less than the set value.
3. The control method for preventing excessive inrush current when the charger is started according to claim 2, characterized in that: The setting method also includes: before turning on the MOS tube of the charging circuit, setting the reference voltage of the current feedback loop at this time to a first reference voltage, and when the charging current is the rated current, the reference voltage of the current feedback loop is a second reference voltage, and the first reference voltage is less than the second reference voltage.
4. The control method for preventing excessive inrush current when the charger is started according to claim 3, characterized in that: The following steps are involved: Step 1) Connect the charger to the battery; Step 2) Turn off the MOS tube of the charging circuit; Step 3) Detect the current voltage of the battery; Step 4) Whether the charger output voltage is greater than the battery voltage, and the difference between the charger output voltage and the battery voltage is less than the set value, if yes, execute step 6), if not, execute step 5); Step 5) Adjust the output voltage of the charger and then return to step 4); Step 6) setting the reference voltage of the current feedback loop at this time to be the first reference voltage, and when the charging current is the rated current, the reference voltage of the current feedback loop to be the second reference voltage, so that the first reference voltage is less than the second reference voltage; Step 7) Turn on the MOS tube of the charging circuit; Step 8) Delay setting time; Step 9) Gradually increase the charging current to the rated current according to the setting method.
5. A control system for implementing the control method for preventing excessive inrush current when a charger is started as claimed in claim 1, characterized in that: It includes a microcontroller and a charging circuit, wherein the charging circuit includes a current feedback loop, a voltage feedback loop and a MOS tube; the microcontroller is electrically connected to the output end of the charger, the battery, the voltage feedback loop and the current feedback loop respectively, and the microcontroller is used to collect the output voltage, output current and battery voltage of the charger; Before turning on the MOS tube of the charging circuit, the microcontroller adjusts the reference voltage of the voltage feedback loop according to the collected output voltage of the charger and the battery voltage, so that the output voltage of the charger is greater than the battery voltage, and the difference between the output voltage of the charger and the battery voltage is less than the set value; and before turning on the MOS tube of the charging circuit, the microcontroller adjusts the reference voltage of the current feedback loop at this time to be a first reference voltage, and makes the first reference voltage less than a second reference voltage, and the second reference voltage is the reference voltage of the current feedback loop when the charging current is the rated current.
6. The control system according to claim 5, characterized in that: It also includes a photocoupler U1, a transformer and an LLC resonant circuit, wherein the primary input winding of the transformer is used to be connected to the charger end, the secondary output winding of the transformer is used to be connected to the battery end, the LLC resonant circuit is connected to the primary input winding of the transformer, the gain change of the LLC resonant circuit causes the output voltage of the transformer to change, the input end of the photocoupler U1 is respectively connected to the voltage feedback loop and the current feedback loop, and the output end of the photocoupler U1 is connected to the LLC resonant circuit, so that the output change of the voltage feedback loop and the current feedback loop causes the change of the output of the photocoupler U1, and the change of the output of the photocoupler U1 causes the gain change of the LLC resonant circuit.
7. The control system according to claim 6, characterized in that: The current feedback loop includes an operational comparator U2, a non-inverting input terminal of the operational comparator U2 is connected to the microcontroller, and an output terminal of the operational comparator U2 is connected to the photoelectric coupler U1; Before turning on the MOS tube of the charging circuit, the microcontroller adjusts the first reference voltage of the non-inverting input terminal of the operational comparator U2 to be lower than the second reference voltage, so that the operational comparator U2 outputs a low level. When the operational comparator U2 outputs a low level, the output voltage of the photocoupler U1 is reduced, and the gain of the LLC resonant circuit is reduced, so that the charging current of the charger is below the rated value at this time.
8. The control system according to claim 6, characterized in that: The voltage feedback loop includes a voltage stabilizer Z1, a cathode of the voltage stabilizer Z1 is connected to the photocoupler U1, an anode of the voltage stabilizer Z1 is grounded, and a control electrode of the voltage stabilizer Z1 is connected to the microcontroller; Before turning on the MOS tube of the charging circuit, the microcontroller detects the battery voltage and adjusts the control electrode voltage of the voltage regulator Z1 to turn on the voltage regulator Z1, increase the current flowing through the photoelectric coupler, reduce the output voltage of the photoelectric coupler, reduce the gain of the LLC resonant circuit, and reduce the output voltage of the charger until the difference between the output voltage of the charger and the battery voltage is less than the set value.
9. The control system according to claim 7, characterized in that: After the MOS tube of the charging circuit is turned on and during constant current charging, the operational comparator U2 outputs a low level when the output current of the charger is greater than the rated current. When the operational comparator U2 outputs a low level, the output voltage of the photocoupler U1 is reduced, the gain of the LLC resonant circuit is reduced, and the output current of the charger is reduced and finally stabilized at the rated current; the operational comparator U2 outputs a high level when the output current of the charger is less than the rated current. When the operational comparator U2 outputs a high level, the output voltage of the photocoupler U1 is increased, the gain of the LLC resonant circuit is increased, and the output current of the charger is increased and finally stabilized at the rated current.
10. The control system according to claim 8, characterized in that: After the MOS tube of the charging circuit is turned on and during constant voltage charging, when the output voltage of the charger is greater than the rated voltage, the control electrode voltage of the voltage regulator Z1 is greater than the reference voltage of the voltage regulator Z1, so that the voltage regulator Z1 is turned on, the current flowing through the photocoupler U1 increases, the output terminal voltage of the photocoupler U1 decreases, the gain of the LLC resonant circuit decreases, and the output voltage of the charger decreases until the output voltage of the charger stabilizes at the rated voltage; when the output voltage of the charger is less than the rated voltage, the control electrode voltage of the voltage regulator Z1 is less than the reference voltage of the voltage regulator Z1, so that the voltage regulator Z1 is turned off, the current flowing through the photocoupler U1 decreases, the output terminal voltage of the photocoupler U1 increases, the gain of the LLC resonant circuit increases, and the output voltage of the charger increases until the output voltage of the charger stabilizes at the rated voltage.