CN120710167A - Charging control method of charging circuit, charger and energy storage device - Google Patents

Abstract

The application discloses a charging control method of a charging circuit, a charger and energy storage equipment, wherein the input end of the charging circuit is connected with a vehicle storage battery, the output end of the charging circuit is connected with the energy storage equipment, the vehicle storage battery charges the energy storage equipment through the charging circuit, the charging circuit comprises a voltage control loop, the charging control method comprises the steps of detecting input voltage of the input end of the charging circuit in real time, comparing the input voltage with a first threshold voltage, and starting the voltage control loop to adjust output power of the charging circuit under the condition that the input voltage is smaller than or equal to the first threshold voltage, so that the input voltage approaches to or is equal to the first threshold voltage. Therefore, the phenomenon of power shortage when the vehicle storage battery charges the battery module can be avoided, and the vehicle storage battery is effectively protected.

Description

Charging control method of charging circuit, charger and energy storage device

Technical Field

The present application relates to the field of energy storage technologies, and in particular, to a charging control method of a charging circuit, a charger, and an energy storage device.

Background

The portable energy storage device is a portable energy storage device internally provided with a lithium ion battery or other types of batteries, has various output interfaces, can provide stable power supply for electronic devices such as mobile phones, tablet computers, notebook computers, cameras and small household appliances, is suitable for various scenes such as outdoor travel, emergency disaster relief, mobile office and the like, and is convenient for people to meet power requirements under the condition of no mains supply.

In the related art, when a vehicle runs, electric energy generated by an engine is transmitted to a charger through a vehicle storage battery, and then is output to energy storage equipment after direct current conversion by the charger, so that the energy storage equipment is charged. However, the connection between the car battery and the car battery is typically through a long cable, which can result in significant line voltage drops when the long cable delivers a large current (often up to 20-50A) to the charger. The voltage of the input end of the charger is lower than the actual voltage of the storage battery, and when the actual voltage of the storage battery approaches to the undervoltage protection threshold (voltage shortage), the storage battery can be subjected to the voltage shortage condition if the input end of the charger is not controlled, so that the actual use of the vehicle is affected.

Disclosure of Invention

The embodiment of the application provides a charging control method of a charging circuit, a charger and energy storage equipment.

According to the charging control method of the charging circuit, the input end of the charging circuit is connected with the vehicle storage battery, the output end of the charging circuit is connected with the energy storage device, the vehicle storage battery charges the energy storage device through the charging circuit, the charging circuit comprises a voltage control loop, and the charging control method comprises the following steps:

Detecting the input voltage of the input end of the charging circuit in real time;

comparing the input voltage with a first threshold voltage;

In the event that the input voltage is less than a first threshold voltage, the voltage control loop is activated to regulate the output power of the charging circuit such that the input voltage approaches or equals the first threshold voltage.

In some embodiments, the charge control method further comprises:

and controlling the charging circuit to charge the energy storage device with a preset output power under the condition that the input voltage is larger than a first threshold voltage.

In some embodiments, the charging circuit further includes a switch module and a voltage adjustment module, the switch module is connected in series with the voltage adjustment module, an input end of the switch module is connected with the vehicle storage battery, the voltage adjustment module is connected with the energy storage device, and the charging control method further includes:

comparing the input voltage with a second threshold voltage, the second threshold voltage being less than the first threshold voltage;

and when the input voltage is larger than the second threshold voltage, controlling the switch module to be closed, so that the switch module transmits the input voltage to the voltage adjustment module, and outputting power to the energy storage device by the voltage adjustment module.

In some embodiments, the charge control method further comprises:

And controlling the switch module to be turned off when the input voltage is smaller than the second threshold voltage, so that the switch module stops transmitting the input voltage to the voltage regulating circuit.

In some embodiments, the voltage control loop is coupled to the voltage adjustment module, and in the event that the input voltage is less than a first threshold voltage, the voltage control loop is enabled to adjust the output power of the charging circuit such that the input voltage approaches or equals the first threshold voltage, comprising:

The voltage control loop is activated to regulate an output power of the voltage regulation module such that the input voltage approaches or equals the first threshold voltage.

In some embodiments, the first threshold voltage is equal to an under-voltage protection threshold of the vehicle battery and the second threshold voltage is less than the under-voltage protection threshold of the vehicle battery.

In some embodiments, the charge control method further comprises:

the voltage control loop control is exited when the input voltage is greater than a third threshold voltage, the third threshold voltage being greater than the first threshold voltage.

The charger of the embodiment of the application comprises a charging circuit, wherein the input end of the charging circuit is connected with a vehicle storage battery, the output end of the charging circuit is connected with energy storage equipment, the vehicle storage battery charges the energy storage equipment through the charging circuit, the charging circuit comprises a voltage control loop, and the charger comprises:

the detection circuit is used for detecting the input voltage of the input end of the charging circuit in real time;

A comparison circuit for comparing the input voltage with a first threshold voltage;

and the control circuit is used for starting the voltage control loop to adjust the output power of the charging circuit so that the input voltage approaches or equals to the first threshold voltage under the condition that the input voltage is smaller than or equal to the first threshold voltage.

The energy storage device provided by the embodiment of the application comprises a charging circuit, a battery module and a controller, wherein the input end of the charging circuit is connected with a vehicle storage battery, the output end of the charging circuit is connected with the battery module, the vehicle storage battery charges the battery module through the charger, and the controller is used for:

Detecting the input voltage of the input end of the charging circuit in real time;

comparing the input voltage with a first threshold voltage;

In the event that the input voltage is less than or equal to a first threshold voltage, the voltage control loop is activated to regulate the output power of the charging circuit such that the input voltage approaches or equals the first threshold voltage.

According to the charging control method, the charger and the energy storage device, when the vehicle storage battery charges the energy storage device through the charging circuit, the input voltage of the charging circuit is detected in real time, the input voltage is compared with the first threshold voltage, and under the condition that the input voltage is smaller than or equal to the first threshold voltage, the voltage control loop is started to adjust the output power of the charging circuit, so that the input voltage approaches or equal to the first threshold voltage, line loss caused by connection of the vehicle storage battery and the charging circuit can be reduced, damage to the vehicle storage battery due to the phenomenon of power shortage caused by continuous charging of the vehicle storage battery to the energy storage device is avoided, and charging safety of the vehicle storage battery is improved.

Drawings

The foregoing and/or additional aspects and advantages of the application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

fig. 1 is a flow chart of a charge control method according to some embodiments of the present application.

Fig. 2 is a block diagram of a charger according to some embodiments of the application.

FIG. 3 is a schematic illustration of a scenario in which a vehicle battery charges an energy storage device according to some embodiments of the present application.

Fig. 4-7 are flow diagrams of charge control methods according to certain embodiments of the present application.

Detailed Description

Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present application and are not to be construed as limiting the present application.

Referring to fig. 1, the application provides a charging control method of a charging circuit, wherein an input end of the charging circuit is connected with a vehicle storage battery, an output end of the charging circuit is connected with an energy storage device, the vehicle storage battery charges the energy storage device through the charging circuit, the charging circuit comprises a voltage control loop, and the charging control method comprises the following steps:

01, detecting the input voltage of the input end of the charging circuit in real time;

02, comparing the input voltage with a first threshold voltage;

03, in case the input voltage is less than or equal to the first threshold voltage, starting the voltage control loop to adjust the output power of the charging circuit such that the input voltage approaches or equals the first threshold voltage.

Referring to fig. 2, the present application further provides a charger 100, where the charger 100 includes a charging circuit 10, a detection circuit 20, a comparison circuit 30 and a control circuit 40, the input end of the charging circuit 10 is connected to a vehicle storage battery, the output end is connected to an energy storage device, the vehicle storage battery charges the energy storage device through the charging circuit, and the charging circuit includes a voltage control loop. Step 01 described above may be implemented by the detection circuit 20, step 02 may be implemented by the comparison circuit 30, and step 03 described above may be implemented by the control circuit 40.

Alternatively, the detection circuit 20 is configured to detect an input voltage at an input terminal of the charging circuit in real time, the comparison circuit 30 is configured to compare the input voltage with a first threshold voltage, and the control circuit 40 is configured to activate the voltage control loop to adjust the output power of the charging circuit if the input voltage is less than or equal to the first threshold voltage.

Referring to fig. 3, the present application further provides an energy storage device 1000, where the energy storage device 1000 includes a charging circuit 10, a battery module 200, and a controller 300, and the controller 300 is configured to detect an input voltage of an input terminal of the charging circuit in real time, compare the input voltage with a first threshold voltage, and start a voltage control loop to adjust an output power of the charging circuit when the input voltage is less than or equal to the first threshold voltage, so that the input voltage approaches or equals to the first threshold voltage.

In the charge control method, the charger 100 and the energy storage device 1000, when the vehicle storage battery charges the energy storage device through the charging circuit, the input voltage of the input end of the charging circuit is detected in real time, the input voltage is compared with the first threshold voltage, and under the condition that the input voltage is smaller than or equal to the first threshold voltage, the voltage control loop is started to adjust the output power of the charging circuit, so that the input voltage approaches or equal to the first threshold voltage, thereby reducing the line loss caused by the connection of the vehicle storage battery and the charging circuit, avoiding the phenomenon of power shortage caused by the continuous charging of the vehicle storage battery to the battery module, damaging the vehicle storage battery, and improving the charge safety of the vehicle storage battery.

In particular, the charging circuit 10 may be a product that is separate from the energy storage device 1000, or may be integrated within the energy storage device as part of the energy storage device 1000. Where the charging circuit 10 is independent of the product other than the energy storage device 1000, the charging circuit 10 may be part of the charger 100, or the charger 100 may include the charging circuit 10 (as shown in fig. 2), so that the charger 100 may charge different energy storage devices 100. When the charging circuit 10 is also part of the energy storage device 1000, it is integrated within the energy storage device 1000, or the energy storage device 1000 includes the charging circuit 10 (as shown in fig. 3), so that the vehicle-mounted storage battery charges the battery module 200 when the charging circuit 10 of the energy storage device 1000 is connected.

The energy storage device 1000 refers to a device capable of storing power. The energy storage device 1000 is provided with a rechargeable battery module 200, a large amount of power is stored through the battery module 200 in the energy storage device 1000, and the energy storage device 1000 outputs the electric energy stored in the battery module 200 for use when necessary. In this embodiment, the energy storage device 1000 may be a portable energy storage device 1000, for example, the energy storage device 1000 may be a portable outdoor power source, and it should be noted that the portable energy storage device 1000 is a portable and portable electric energy storage and supply device.

Referring to fig. 2 or 3, the charging circuit 10 may be a DC-DC circuit, i.e., a circuit for converting direct current into direct current, an input end of the charging circuit 10 may be detachably and electrically connected to a vehicle storage battery, an output end of the charging circuit 10 may be detachably and electrically connected to the energy storage device 1000 when the charging circuit 10 is used as a part of the charger 100, and an output end of the charging circuit 10 may be fixedly and electrically connected to the battery module 200 when the charging circuit 10 is integrated into the energy storage device 1000. The charging circuit 10 includes a voltage control loop 11, and the voltage control loop 11 is used for adjusting the output power of the charging circuit 10.

Further, when the vehicle battery is charged, it is necessary to connect the battery with the charging circuit 10 through the connection harness, the storage voltage of the battery is relatively low (typically about 12V or 14.8V), the charging circuit 10 needs to obtain relatively high power, and the discharging current of the vehicle battery needs to be relatively high, if the connection harness is relatively long, the upper line loss of the connection harness is relatively high, so that a relatively high pressure difference exists between the input voltage of the input end of the charging circuit 10 and the storage voltage of the vehicle, and if the input voltage of the input end is not controlled, the battery may be subjected to power shortage, thereby affecting the actual use of the vehicle.

Therefore, in this embodiment, when the vehicle battery normally charges the energy storage device 1000 through the charging circuit 10, the input voltage of the charging circuit 10 is detected in real time, and then the detected input voltage is compared with the first threshold voltage, when the input voltage of the input end of the charging circuit 10 is greater than or equal to the first threshold voltage, the charging circuit normally outputs a high power, the connecting harness has a line loss, the voltage of the vehicle battery is greater than the input voltage of the input end of the charging circuit 10, the voltage of the vehicle battery=the divided voltage of the connecting harness+the input voltage, the vehicle battery does not have a power shortage phenomenon, the high power output can improve the charging efficiency, when the input voltage is smaller than the first threshold voltage, the voltage control loop 11 of the charging circuit 10 is started to adjust the output power of the charging circuit 10, so that the input voltage of the input end of the charging circuit 10 approaches to or equals the first threshold voltage, the output current of the charging circuit 10 is reduced, the line loss is reduced (the resistance is a fixed value, the voltage lost at the line harness is u=i×r, the voltage lost at the line harness is smaller, the corresponding detected the voltage is higher the voltage is guaranteed the higher the voltage is always the higher the voltage than the first threshold voltage, and the vehicle battery is prevented from being continuously charged to the first threshold voltage 200.

It should be noted that the first threshold voltage is a preset voltage value, the first threshold voltage may be related to an under-voltage protection threshold of the vehicle battery, and the first threshold voltage may be substantially equal to the under-voltage protection threshold of the vehicle battery. For example, the undervoltage protection threshold of the battery is 11V, and the first threshold voltage may be 11V, 11.05V, 11.1V, or the like.

The voltage control loop 11 is a closed loop feedback controller (such as a PID controller, which adjusts the energy output of the voltage adjustment module 13 by three control items of Proportional (P), integral (I) and differential (D) for achieving the purpose of stable and fast response) for controlling the input energy during the charging process of the charging circuit 10. The main purpose of the voltage control loop 11 is to ensure that the charging circuit 10 can operate safely and efficiently during charging and to maintain a stable charging process when the input voltage fluctuates.

The voltage control loop 11 can adjust the energy output of the energy storage device 1000 to be continuously close to the target value based on the set target value, and perform feedback control by detecting the adjusted energy output. If the current energy output is larger than the target value, after the energy output is reduced based on the preset step length, the energy output is continuously reduced based on the preset step length after the energy output is detected to be still larger than the target value, and the adjustment is stopped until the energy output is reduced based on the preset step length and reaches the target value or the difference value between the energy output and the target value is smaller than the threshold value. In this embodiment, the voltage control loop 11 is not started when the input voltage is greater than the first threshold voltage, so as to ensure the charging efficiency of the charging circuit 10, and is started when the input voltage is less than the first threshold voltage, so as to adjust the output power of the output end of the charging circuit 10, so that the input voltage approaches or equals to the first threshold voltage, and the phenomenon of voltage shortage caused by continuous high-power output of the vehicle storage battery is avoided.

In some examples, the voltage control loop 11 may adjust the output power of the charging circuit 10 by adjusting the duty cycle of the pulse width modulation such that the input voltage approaches or equals the first threshold voltage. It will be appreciated that the larger the duty cycle of the pulse width modulation, the longer the on-time of the power switch in the charging circuit 10, the larger the output power, whereas the smaller the duty cycle of the pulse width modulation, the shorter the on-time of the power switch in the charging circuit 10, the smaller the output power.

Referring to fig. 4, in some embodiments, the charging control method further includes:

04, controlling a charging circuit to charge the energy storage device with a predetermined output power in case that the input voltage is greater than a first threshold voltage.

In some embodiments, step 04 may be implemented by the control circuit 40, or the control circuit 40 may be further configured to control the charging circuit to charge the energy storage device at a predetermined output power if the input voltage is greater than the first threshold voltage.

In some embodiments, the controller may be further configured to control the charging circuit to charge the battery module with a predetermined output power when the input voltage is greater than the first threshold voltage.

Therefore, when the input voltage is larger than the first threshold voltage, the charging circuit is controlled to charge the energy storage device with the preset output power, so that the charging efficiency of the charging circuit can be ensured, and the charging time of the energy storage device is shortened.

Referring to fig. 2 and 5, in some embodiments, the charging circuit 10 further includes a switch module 12 and a voltage adjustment module 13, the switch module 12 is connected in series with the voltage adjustment module 13, an input end of the switch module 12 is connected to a vehicle battery, the voltage adjustment module 13 is connected to the energy storage device 1000, and the charging control method further includes:

05, comparing the input voltage with a second threshold voltage, wherein the second threshold voltage is smaller than the first threshold voltage;

06, in case the input voltage is greater than the second threshold voltage, controlling the switching module to close such that the switching module transmits the input voltage to the voltage regulation module, the voltage regulation module outputs power to the energy storage device, or

07, Controlling the switching module to be turned off in case that the input voltage is less than the second threshold voltage, such that the switching module stops transmitting the input voltage to the voltage regulating circuit.

In some embodiments, step 05 may be implemented by the comparison circuit 30, step 06 may be implemented by the control circuit 40, or the comparison circuit 30 may be further configured to compare the input voltage with a second threshold voltage, which is smaller than the first threshold voltage, and the control circuit 40 may be further configured to control the switching module to be closed when the input voltage is greater than the second threshold voltage, so that the switching module transmits the input voltage to the voltage adjustment module, output power to the energy storage device by the voltage adjustment module, or to control the switching module to be turned off when the input voltage is less than the second threshold voltage, so that the switching module stops transmitting the input voltage to the voltage adjustment circuit.

In some embodiments, the controller 300 is configured to compare the input voltage with a second threshold voltage, the second threshold voltage being less than the first threshold voltage, and to control the switch module to close if the input voltage is greater than the second threshold voltage, such that the switch module transmits the input voltage to the voltage regulation module, output power to the energy storage device by the voltage regulation module, or to control the switch module to close if the input voltage is less than the second threshold voltage, such that the switch module stops transmitting the input voltage to the voltage regulation circuit.

The first threshold voltage is equal to an under-voltage protection threshold of the vehicle battery, and the second threshold voltage is smaller than the under-voltage protection threshold of the vehicle battery.

Specifically, the input voltage is compared with the second threshold voltage, if the input voltage is greater than the second threshold voltage, it is indicated that the voltage of the vehicle battery meets the output requirement, at this time, if the charging circuit 10 is integrated in the charger 100, the control circuit 40 controls the switch module 12 to be closed, so that the input voltage of the charging circuit 10 is transmitted to the voltage adjustment module 13 through the switch module 12, and then the input voltage is adjusted by the voltage adjustment module 13 and output to the energy storage device 1000 (as shown in fig. 2), and if the charging circuit 10 is integrated in the energy storage device 1000, the switch module 12 is controlled to be closed by the controller 300, so that the input voltage of the input end of the charging circuit 10 is transmitted to the voltage adjustment module 13 through the switch module 12, and then the input voltage is adjusted by the voltage adjustment module 13 and output to the battery module 200. In this way, it is ensured that the vehicle battery can be charged to the energy storage device 1000 by the charging circuit 10.

If the input voltage is less than the second threshold voltage, the voltage of the vehicle storage battery is not satisfied with the output requirement. At this time, if the charging circuit 10 is integrated in the charger 100, the control circuit 40 controls the switching module 12 to be turned off, so that the input voltage of the charging circuit 10 cannot be transmitted from the switching module 12 to the voltage adjustment module 13, and the charger 100 cannot charge the energy storage device 1000, and if the charging circuit 10 is integrated in the energy storage device 1000, the controller 300 controls the switching module 12 to be turned off, so that the input voltage of the input end of the charging circuit 10 cannot be transmitted from the switching module 12 to the voltage adjustment module 13, and the charging circuit 10 cannot charge the battery module 200. Therefore, the over-discharge condition is avoided when the voltage of the vehicle storage battery is insufficient, and the service life of the vehicle storage battery is prolonged.

Referring to fig. 6, in some embodiments, the voltage control loop 11 is connected to the voltage adjustment module 13, and step 03 includes:

031, starting a voltage control loop to adjust the output power of the voltage adjustment module such that the input voltage approaches or equals the first threshold voltage.

In some embodiments, step 031 may be implemented by the control circuit 40, or the control circuit 31 may also be configured to start a voltage control loop to adjust the output power of the voltage adjustment module so that the input voltage approaches or equals the first threshold voltage.

In some embodiments, the controller may be configured to initiate a voltage control loop to regulate the output power of the voltage regulation module such that the input voltage approaches or equals the first threshold voltage.

Specifically, when the input voltage is smaller than the first threshold voltage, the voltage control loop 11 of the charging circuit 10 is started to regulate the output power, so that the input voltage at the input end of the charging circuit 10 approaches to or is equal to the first threshold voltage, and the output current of the charging circuit 10 is reduced, so that the line loss is reduced, and the voltage of the vehicle storage battery is always greater than or equal to the first threshold voltage, thus avoiding the phenomenon of power shortage of the vehicle storage battery caused by continuously charging the battery module 200, and improving the charging safety of the storage battery.

Referring to fig. 7, in some embodiments, the charging control method further includes:

08, exiting the voltage control loop control if the input voltage is greater than a third threshold voltage, the third threshold voltage being greater than the first threshold voltage.

In some embodiments, step 08 may be implemented by the control circuit 40, or the control circuit 40 may be further configured to exit the voltage control loop control if the input voltage is greater than a third threshold voltage, the third threshold voltage being greater than the first threshold voltage.

In some embodiments, the controller 300 may be configured to exit the voltage control loop control if the input voltage is greater than a third threshold voltage, the third threshold voltage being greater than the first threshold voltage.

It will be appreciated that if a single threshold comparison is used, a slight voltage fluctuation may cause the voltage control loop 11 to switch frequently between "on" and "off" states. Therefore, by setting the trigger threshold (the first threshold voltage) lower than the exit threshold (the third threshold voltage), a hysteresis band is formed, the control action of the exit voltage control loop 11 is triggered only when the input voltage deviates from the target value remarkably, the control oscillation caused by voltage fluctuation is effectively restrained, the state of the charging circuit is prevented from being frequently switched nearby the threshold value, the loss of a power device is reduced, meanwhile, the hysteresis band provides buffering for the dynamic change of the input voltage of the storage battery, the charging and discharging characteristics of the battery are adapted, the low-power protection is preferentially ensured through the asymmetric threshold design (low trigger and high exit), the stability and the response sensitivity of the system are both considered, and the overall energy management reliability is finally improved.

The foregoing examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims (9)

1. A charging control method for a charging circuit, characterized in that the input end of the charging circuit is connected to a vehicle battery and the output end is connected to an energy storage device, the vehicle battery charges the energy storage device through the charging circuit, the charging circuit includes a voltage control loop, and the charging control method includes: detecting the input voltage of the input end of the charging circuit in real time; comparing the input voltage with a first threshold voltage; When the input voltage is less than a first threshold voltage, the voltage control loop is started to adjust the output power of the charging circuit so that the input voltage approaches or is equal to the first threshold voltage. 2. The charging control method according to claim 1, further comprising: When the input voltage is greater than a first threshold voltage, the charging circuit is controlled to charge the energy storage device at a predetermined output power. 3. The charging control method according to claim 2, wherein the charging circuit further comprises a switch module and a voltage adjustment module, the switch module and the voltage adjustment module are connected in series, an input end of the switch module is connected to the vehicle battery, and the voltage adjustment module is connected to the energy storage device, and the charging control method further comprises: comparing the input voltage with a second threshold voltage, the second threshold voltage being less than the first threshold voltage; When the input voltage is greater than the second threshold voltage, the switch module is controlled to be closed, so that the switch module transmits the input voltage to the voltage adjustment module, and the voltage adjustment module outputs power to the energy storage device. 4. The charging control method according to claim 3, further comprising: When the input voltage is less than the second threshold voltage, the switch module is controlled to be turned off, so that the switch module stops transmitting the input voltage to the voltage regulation circuit. 5. The charging control method according to claim 3, wherein the voltage control loop is connected to the voltage adjustment module, and when the input voltage is less than a first threshold voltage, the voltage control loop is activated to adjust the output power of the charging circuit so that the input voltage approaches or is equal to the first threshold voltage, comprising: The voltage control loop is started to adjust the output power of the voltage regulation module so that the input voltage approaches or is equal to the first threshold voltage. 6 . The charging control method according to claim 4 , wherein the first threshold voltage is equal to an undervoltage protection threshold of the vehicle battery, and the second threshold voltage is less than the undervoltage protection threshold of the vehicle battery. 7. The charging control method according to claim 1, further comprising: When the input voltage is greater than a third threshold voltage, the voltage control loop control is exited, and the third threshold voltage is greater than the first threshold voltage. 8. A charger, characterized in that the charger includes a charging circuit, wherein the input end of the charging circuit is connected to a vehicle battery and the output end is connected to an energy storage device, and the vehicle battery charges the energy storage device through the charging circuit, the charging circuit includes a voltage control loop, and the charger further includes: a detection circuit, configured to detect in real time the input voltage of the input end of the charging circuit; a comparison circuit, configured to compare the input voltage with a first threshold voltage; The control circuit is configured to start the voltage control loop to adjust the output power of the charging circuit when the input voltage is less than or equal to a first threshold voltage, so that the input voltage approaches or is equal to the first threshold voltage. 9. An energy storage device, characterized in that the energy storage device includes a charging circuit, a battery module, and a controller, wherein the input end of the charging circuit is connected to a vehicle battery and the output end is connected to the battery module, the vehicle battery charges the battery module through the charging circuit, the charging circuit includes a voltage control loop, and the controller is configured to: detecting the input voltage of the input end of the charging circuit in real time; comparing the input voltage with a first threshold voltage; When the input voltage is less than or equal to a first threshold voltage, the voltage control loop is started to adjust the output power of the charging circuit so that the input voltage approaches or is equal to the first threshold voltage.