Battery charging device, method and controller

Abstract

The present application discloses a battery charging device, method and controller. The battery charging device includes: a first switch, a second switch, a third switch and a fourth switch connected in series between an input voltage bus and a ground, wherein a common node of the second switch and the third switch is configured to be coupled to a battery; a flying capacitor connected between a common node of the first switch and the second switch and a common node of the third switch and the fourth switch; and a controller configured to generate a gate drive signal, the gate drive signal being used to configure at least one of the first switch and the second switch as a linear regulator during battery charging.

Description

Technical Field

[0001] The present invention relates to a battery charging device, method and controller. In some specific embodiments, the present invention relates to a battery charging device, method and controller based on a switched capacitor power converter. Background Art

[0002] With the continuous advancement of technology, various electronic devices (such as mobile phones, tablet computers, digital cameras, MP3 players and / or other similar electronic devices) have become popular. Each portable device may use a plurality of rechargeable battery cells. These rechargeable battery cells may be connected in series or in parallel to form a rechargeable battery pack for storing electrical energy.

[0003] The battery charger is used to restore the energy of the battery. The battery charger is controlled to provide voltage (eg, constant voltage charging mode) and current (eg, constant current charging mode) to the battery in order to restore the energy of the battery.

[0004] There may be many different power conversion topologies suitable for charging a battery. According to the different topologies, the power conversion topologies can be divided into three categories, namely, switching power converters, linear regulators, and switched capacitor power converters (hereinafter referred to as switched capacitor converters or switched capacitor power converters). Compared with other topologies, the switched capacitor converter is less complex because it consists of multiple switches and a flying capacitor. Therefore, the switched capacitor converter can provide a compact and efficient power supply for battery charging.

[0005] The battery charging process includes five stages, namely, the trickle charging stage, the pre-charging stage, the constant current charging stage, the constant voltage charging stage and the end charging stage. When the battery is fully discharged (for example, the battery voltage of a single battery is less than 2V), the battery charger operates in the trickle charging stage. In the trickle charging stage, a constant current is injected into the battery, and the battery voltage gradually increases. The trickle charging current is in the range of about 20mA to about 100mA. Once the battery voltage reaches the pre-charging threshold (for example, 2.2V), the battery charger will be configured to operate in the pre-charging stage. The pre-charging current is about one-tenth of the constant charging current. In the pre-charging stage, the battery voltage continues to rise. Once the battery voltage exceeds the constant current charging threshold (for example, 3.0V), the battery charger will be configured to operate in the constant current charging stage. The charging current is increased as a constant current charge. In the constant current charging stage, the battery voltage gradually increases. For a single battery, the battery voltage increases from about 3.0V to about 4.2V. Once the battery voltage reaches the constant voltage charging threshold (for example, 4.2V), the battery charger will be configured to operate in the constant voltage charging stage. During the constant voltage charging phase, the charging current gradually decreases. The battery voltage remains at the constant voltage charging threshold. At the end of the charging phase, the battery is nearly fully charged. The battery charger continues to operate for a predetermined period of time until the battery charging process is complete.

[0006] In the constant voltage charging stage, the charging current starts from a large charging current and gradually decreases to a small charging current, and the battery voltage remains constant. The constant voltage charging stage with a large charging current and the constant current charging stage can be collectively referred to as a fast charging stage.

[0007] In order to meet the requirements of the above five charging stages, a conventional battery charger must include at least two power converters. For example, a switching charger and / or a linear regulator is used to power a trickle charging stage, a pre-charging stage, a constant voltage charging stage with a small charging current, and an end charging stage. A switched capacitor power converter is used to power a fast charging stage to achieve high charging efficiency. However, a battery charger with multiple power converters is not cost-effective. Therefore, it is desirable to provide a simple and reliable battery charger to complete the above five charging stages. Summary of the invention

[0008] The present disclosure provides a battery charging device, method and controller. In some preferred embodiments of the present disclosure, the above-mentioned problems and other problems are generally solved or avoided, and technical advantages can be obtained.

[0009] According to one embodiment, a battery charging device is provided, comprising: a first switch, a second switch, a third switch and a fourth switch connected in series between an input voltage bus and a ground, wherein a common node of the second switch and the third switch is configured to be coupled to a battery; a flying capacitor connected between a common node of the first switch and the second switch and a common node of the third switch and the fourth switch; and a controller configured to generate a gate drive signal to configure at least one of the first switch and the second switch as a linear regulator during charging of the battery.

[0010] According to another embodiment, a method is provided, comprising: coupling a power converter to a battery, wherein the power converter comprises: a first switch, a second switch, a third switch and a fourth switch connected in series between an input voltage bus and a ground, wherein a common node of the second switch and the third switch is configured to be coupled to the battery; and a flying capacitor connected between a common node of the first switch and the second switch and a common node of the third switch and the fourth switch; and during charging of the battery, configuring at least one of the first switch and the second switch as a linear regulator.

[0011] According to yet another embodiment, a controller is provided, comprising: a plurality of gate drivers configured to generate a plurality of gate drive signals to drive a switched capacitor power converter, wherein: the switched capacitor power converter is used to charge a battery; and during the charging process of the battery, the gate drive signal is configured to cause at least one switch in the switched capacitor power converter to be configured as a linear regulator.

[0012] The above description broadly summarizes the features and technical advantages of the present disclosure so that the following detailed description of the present disclosure can be better understood. Additional features and advantages of the present disclosure will be described below, and these additional features and advantages also constitute the subject matter protected by the claims of the present disclosure. It should be understood by those skilled in the art that, based on the concepts and specific embodiments of the present disclosure, it is easy to modify and design other structures or processes that have the same purpose as the present disclosure. It should also be recognized by those skilled in the art that these equivalent structures do not deviate from the spirit and scope of the present disclosure as set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more fully understand the present disclosure and its advantages, the following description is now provided for reference in conjunction with the accompanying drawings, in which:

[0014] Figure 1 A schematic diagram of a battery charging device according to an embodiment of the present disclosure is shown;

[0015] Figure 2 A first implementation of configuring a switch of a battery charging device as a linear regulator according to an embodiment of the present disclosure is shown;

[0016] Figure 3 A second implementation of configuring a switch of a battery charging device as a linear regulator according to an embodiment of the present disclosure is shown;

[0017] Figure 4 An implementation of configuring two switches of a battery charging device as a linear regulator according to an embodiment of the present disclosure is shown;

[0018] Figure 5 The embodiment according to the present disclosure is shown Figure 1 The battery charging device shown is configured to operate in a charge pump mode;

[0019] Figure 6 The method for controlling the Figure 1 A flowchart of a method for charging a battery shown; and

[0020] Figure 7 The embodiment of the present disclosure is shown for driving Figure 1 A controller for a switch of a battery charging device is shown.

[0021] In the different drawings, corresponding numerals and symbols are generally used to indicate corresponding parts unless otherwise indicated. These drawings are for the purpose of clearly illustrating the relevant aspects of the various embodiments and are not necessarily and necessarily drawn to scale. DETAILED DESCRIPTION

[0022] The implementation and application of the preferred embodiments of the present disclosure will be discussed in detail below. However, it should be understood that the present disclosure provides many applicable inventive concepts that can be embodied in a variety of specific contexts. The specific embodiments discussed are merely illustrations of some specific ways to implement and apply the present disclosure and do not limit the scope of the present disclosure.

[0023] The present disclosure will describe some preferred embodiments in a specific context, namely a battery charging device and method. However, the present disclosure can also be applied to various other power systems. Below, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0024] Figure 1 Schematic diagram of a battery charging device according to an embodiment of the present disclosure is shown. The battery charging device includes a switched capacitor power converter configured to charge a battery. The switched capacitor power converter includes a first switch Q1, a second switch Q2, a third switch Q3, and a fourth switch Q4 connected in series between an input voltage bus VBUS and ground. A flying capacitor CF is connected between a common node of the first switch Q1 and the second switch Q2 and a common node of the third switch Q3 and the fourth switch Q4. Figure 1As shown, the common node between the second switch Q2 and the third switch Q3 is connected to the output voltage bus VBAT. The output capacitor Co is connected between the output voltage bus VBAT and ground. Figure 1 As shown, the battery is coupled between the output voltage bus VBAT and ground.

[0025] The battery charging device further includes a switch QB connected between the input voltage bus VBUS and the power bus VIN to protect the battery. A power source (not shown) is coupled to the power bus VIN. The power source is configured to provide power for battery charging. Figure 1 As shown, the switch QB is, for example, an N-type transistor. The drain of the switch QB is connected to the input voltage bus VBUS. The source of the switch QB is connected to the power bus VIN. The switch can provide reverse blocking capability to isolate the battery from various system components coupled to the power source VIN.

[0026] Controller( Figure 1 Not shown, but Figure 7 The controller is configured to generate gate drive signals for switches Q1-Q4 and QB. In addition, the controller is configured to control the operating state of each switch based on a plurality of operating parameters and operating modes. In addition, the controller is further configured to generate a gate drive signal during battery charging to configure at least one of the first switch Q1 and the second switch Q2 as a linear regulator. The specific operating principle of the controller will be referred to Figure 2-7 This is described below.

[0027] According to one embodiment, Figure 1 The individual switches shown (e.g., switches Q1-Q4 and QB) may be metal oxide semiconductor field-effect transistor (MOSFET) devices, bipolar junction transistor (BJT) devices, superjunction transistor (SJT) devices, insulated gate bipolar transistor (IGBT) devices, gallium nitride (GaN)-based power devices, and / or the like.

[0028] It should be noted that although Figure 1 The switches Q1-Q4 and QB are shown to be implemented by a single N-type transistor, but those skilled in the art will recognize that there may be many variations, modifications and alternatives. For example, at least one / some of the switches Q1-Q4 and QB may be implemented by a P-type transistor, depending on different applications and design requirements. In addition, Figure 1Each switch shown can be implemented by multiple switches connected in parallel. In addition, a capacitor can be connected in parallel with a switch to implement zero voltage switching (ZVS) / zero current switching (ZCS).

[0029] During operation, the switched capacitor power converter can be configured to provide a small charging current to meet the requirements of various charging stages (including a trickle charging stage, a pre-charging stage, a constant voltage charging stage with a small charging current, and an end charging stage). Based on this configuration, at least one switch of the switched capacitor power converter is configured as a linear regulator to control the current flowing through the battery.

[0030] In some embodiments, the battery charging device is configured to provide a small charging current (e.g., 20 mA during the trickle charging stage), at which time the power loss in the linear regulator is not significant. Therefore, one switch of the switched capacitor power converter is configured as a linear regulator. In some embodiments, switch Q1 can be configured as a linear regulator. The detailed operating principle of this system configuration will be referred to in Figure 2 In other embodiments, the switch Q2 can be configured as a linear regulator. The detailed operation principle of this system configuration will be referred to in Figure 3 Discussed below.

[0031] In some embodiments, the battery charging device is configured to provide a large charging current (e.g., several hundred mA in a constant voltage charging stage), and the power loss in a single linear regulator may cause excessive heat generation, thereby causing reliability issues. To avoid excessive heat generation in a single linear regulator, two switches (e.g., switch Q1 and switch Q2) can be configured as a linear regulator.

[0032] In some embodiments, switch Q1 is configured as a first linear regulator and switch Q2 is configured as a second linear regulator. The two linear regulators are connected in series. The voltage / current regulation of the battery is achieved by controlling the two linear regulators simultaneously. In order to obtain better thermal performance, the voltage drops on the two linear regulators are dynamically adjusted so as to achieve a uniform temperature distribution on the two linear regulators. For example, the controller can detect the temperature of switch Q1 and switch Q2 respectively. Based on the detected temperature, the controller can reduce the gate drive voltage of the switch with a relatively low temperature, thereby increasing the power loss of the switch with a relatively low temperature. On the other hand, the controller can increase the gate drive voltage of the switch with a relatively high temperature, thereby reducing the power loss of the switch with a relatively high temperature. By using the above control mechanism, switch Q1 and switch Q2 can achieve a uniform temperature distribution.

[0033] In some embodiments, configuring switch Q1 as a first linear regulator and configuring switch Q2 as a second linear regulator are performed in an alternating manner. Specifically, the controller can detect the temperatures of switch Q1 and switch Q2, respectively. When the temperature of switch Q1 exceeds a predetermined temperature threshold, the controller configures switch Q1 to exit the linear regulator mode and operate as a normally-on switch, and configures switch Q2 as a linear regulator. Similarly, when the temperature of switch Q2 exceeds a predetermined temperature threshold, the controller configures switch Q2 to exit the linear regulator mode and operate as a normally-on switch, and configures switch Q1 as a linear regulator. By using the above control mechanism, switch Q1 and switch Q2 are configured as linear regulators in an alternating manner.

[0034] During operation, during the fast charging phase of the battery charging process, the switched capacitor power converter can be configured to operate in charge pump mode to achieve high efficiency. In charge pump mode, the switched capacitor power converter acts as a voltage divider. More specifically, the output voltage of the switched capacitor power converter is equal to half of the input voltage. The specific working principle of charge pump mode will be referred to Figure 5 This is described below.

[0035] Figure 2 FIG. 1 shows a first implementation of configuring a switch of a battery charging device as a linear regulator according to an embodiment of the present disclosure. In order to meet the requirements of different charging stages, Figure 1 A switch in the battery charging device shown is configured as a linear regulator. In some embodiments, the linear regulator is a low dropout (LDO) regulator. Figure 2 As shown, switches QB, Q2, and Q4 are fully turned on, as indicated by the thick black lines on the components corresponding to their symbols. In this system configuration, switch Q2 is configured as a first always-on switch, switch Q4 is configured as a second always-on switch, and switch Q3 is turned off (as indicated by the arrow on the component corresponding to its symbol). In this system configuration, switch Q3 acts as an always-off switch. Switch Q1 is configured as a linear regulator.

[0036] During operation, the turned-on switch QB, switch Q2, and linear regulator (Q1) establish a conductive path between the power supply coupled to VIN and the battery BATTERY. The power supply is configured to provide power for charging the battery. The charging current and voltage applied to the battery are controlled and regulated by controlling the operating state of the linear regulator (Q1).

[0037] Figure 3 A second implementation of configuring a switch of a battery charging device as a linear regulator according to an embodiment of the present disclosure is shown. Figure 3The second embodiment shown is Figure 2 The first embodiment shown in FIG. 1 is similar to the first embodiment shown in FIG. 1 , except that the switch Q2 is configured as a linear regulator. Figure 3 As shown, switches QB, Q1, and Q4 are fully open, as indicated by the thick black lines on the components corresponding to their symbols. In this system configuration, switch Q1 is configured as a first normally-on switch, switch Q4 is configured as a second normally-on switch, and switch Q3 is closed (as indicated by the arrow on the component corresponding to its symbol). In this system configuration, switch Q3 acts as a normally-off switch.

[0038] During operation, the turned-on switch QB, switch Q1, and linear regulator (Q2) establish a conductive path between the power supply coupled to VIN and the battery BATTERY. The power supply is configured to provide power for charging the battery. The charging current and voltage applied to the battery are controlled and regulated by controlling the operating state of the linear regulator (Q2).

[0039] Figure 4 The embodiment of configuring two switches of the battery charging device as a linear regulator according to the embodiment of the present disclosure is shown. In order to meet the requirements of different charging stages, Figure 1 The two switches in the battery charging device shown are configured as linear regulators. Switch Q1 is configured as a first linear regulator. Switch Q2 is configured as a second linear regulator. Figure 4 As shown, switches QB, Q4 are fully open, as indicated by the thick black lines on the components corresponding to their symbols. In this system configuration, switch Q4 is configured as a normally-on switch, and switch Q3 is closed (as indicated by the arrows on the components corresponding to their symbols). In this system configuration, switch Q3 is used as a normally-off switch.

[0040] During operation, the turned-on switch QB, the first linear regulator (Q1), and the second linear regulator (Q2) establish a conductive path between the power supply coupled to VIN and the battery BATTERY. The power supply is configured to provide power for charging the battery. The charging current and voltage applied to the battery are controlled and regulated by controlling the operating state of the linear regulators (including Q1 and Q2).

[0041] In some embodiments, configuring the switch Q1 as the first linear regulator and configuring the switch Q2 as the second linear regulator are performed simultaneously. In other embodiments, configuring the switch Q1 as the first linear regulator and configuring the switch Q2 as the second linear regulator are performed in an alternating manner. In addition, the controller is configured to detect the temperature of the switch Q1 and the switch Q2, and based on the temperature of the switch Q1 and the switch Q2, dynamically configure the switch Q1 as the first linear regulator and the switch Q2 as the second linear regulator.

[0042] Figure 5The embodiment according to the present disclosure is shown Figure 1 The battery charging device shown is configured to work in a charge pump mode. In order to achieve high efficiency in the fast charging stage of the battery charging process, the switched capacitor power converter is configured to work in the charge pump mode. Figure 5 As shown, switch QB is fully turned on, as indicated by the thick black line on the element corresponding to its symbol. The controller is configured to control the on and off of switches Q1-Q4 according to the operating principle of the charge pump mode. In the charge pump mode, the switched capacitor power converter acts as a voltage divider. More specifically, the output voltage of the switched capacitor power converter is equal to half of the input voltage.

[0043] In the charge pump mode, the switched capacitor power converter is configured to operate in two different phases. In the first phase, switches Q1 and Q3 are turned on, and switches Q2 and Q4 are turned off. Since switches Q1 and Q3 are turned on, a first conductive path is established between the input voltage bus VBUS and the output voltage bus VBAT. The first conductive path is formed by switch Q1, flying capacitor CF, and switch Q3. Current flows from the input voltage bus VBUS to the output voltage bus VBAT through the first conductive path. In the first phase, the flying capacitor CF is charged and energy is stored in the flying capacitor CF accordingly.

[0044] In the second stage, switches Q1 and Q3 are turned off, and switches Q2 and Q4 are turned on. Since switches Q2 and Q4 are turned on, a second conductive path is established. The second conductive path is formed by switch Q4, flying capacitor CF, and switch Q2. In the second stage, the current flows to discharge the flying capacitor CF, and the energy stored in the flying capacitor CF is reduced accordingly.

[0045] Figure 6 The method for controlling the Figure 1 A flow chart of a method for charging a battery is shown. Figure 6 The flowcharts shown are only examples and should not be overly interpreted as limiting the scope of the claims. A person skilled in the art will recognize that there are many variations, substitutions, and modifications to the various embodiments of the present disclosure. For example, Figure 5-6 The steps shown may be added, deleted, substituted, rearranged and repeated.

[0046] Return to reference Figure 1 The switched capacitor power converter includes a first switch, a second switch, a third switch, and a fourth switch connected in series between an input voltage bus and a ground. A common node of the second switch and the third switch is configured to be coupled to a battery. A flying capacitor is connected between a common node of the first switch and the second switch and a common node of the third switch and the fourth switch.

[0047] In step 602, a switched capacitor power converter is coupled to a battery. An input terminal of the switched capacitor power converter is connected to a power source through a switch. An output terminal of the switched capacitor power converter is connected to the battery.

[0048] In step 604, during the battery charging process, at least one of the first switch and the second switch is configured as a linear regulator. The linear regulator is used to regulate the current flowing through the battery and the voltage across the battery.

[0049] The method further includes: during a trickle charging stage of the battery charging process, configuring at least one of the first switch and the second switch as a linear regulator to charge the battery.

[0050] The method further includes: in a pre-charging stage of the battery charging process, configuring at least one of the first switch and the second switch as a linear regulator to charge the battery.

[0051] The method further includes: configuring at least one of the first switch and the second switch as a linear regulator in a small current portion of a constant voltage charging phase in a process of charging the battery to charge the battery.

[0052] The method further includes: at an end charging stage of the battery charging process, configuring at least one of the first switch and the second switch as a linear regulator to charge the battery.

[0053] The method further includes: configuring the power converter to operate in a charge pump mode during a fast charging phase of a process of charging the battery. The fast charging phase of the battery charging process includes a high current portion of a constant voltage charging phase and a constant current charging phase.

[0054] Return to reference Figure 2 The method further includes: during the battery charging process, configuring the first switch as a linear regulator, configuring the second switch as a first normally-on switch, configuring the third switch as a normally-off switch, and configuring the fourth switch as a second normally-on switch.

[0055] Return to reference Figure 3 The method further includes: during the battery charging process, configuring the first switch as a first normally-on switch, configuring the second switch as a linear regulator, configuring the third switch as a normally-off switch, and configuring the fourth switch as a second normally-on switch.

[0056] Return to reference Figure 4 The method further includes: during the battery charging process, configuring the first switch as a first linear regulator, configuring the second switch as a second linear regulator, configuring the third switch as a normally-off switch, and configuring the fourth switch as a normally-on switch.

[0057] Figure 7The embodiment of the present disclosure is shown for driving Figure 1 Controller 700 includes five gate drivers and a plurality of signal processing devices for processing various operating parameters, such as the current flowing through the battery (IB), the voltage across the battery (VB), and the temperature (T) on the package of the switches Q1-Q4 and QB.

[0058] The first gate driver is configured to generate a first gate drive signal applied to the gate of the switch Q1. The second gate driver is configured to generate a second gate drive signal applied to the gate of the switch Q2. The third gate driver is configured to generate a third gate drive signal applied to the gate of the switch Q3. The fourth gate driver is configured to generate a fourth gate drive signal applied to the gate of the switch Q4. The fifth gate driver is configured to generate a fifth gate drive signal applied to the gate of the switch QB.

[0059] During operation, the first gate driver is configured to apply a first gate drive signal to the gate of the switch Q1, so that the switch Q1 acts as a linear regulator during multiple charging stages during the battery charging process. Similarly, the second gate driver is configured to apply a second gate drive signal to the gate of the switch Q2, so that the switch Q2 acts as a linear regulator during multiple charging stages during the battery charging process.

[0060] In addition, the controller 700 is also used to coordinate the first gate driver and the second gate driver so that both the switch Q2 and the switch Q2 can be used as linear regulators. The above two linear regulators can operate simultaneously. In some embodiments, the voltage drop applied to the two linear regulators is dynamically adjusted to facilitate uniform temperature distribution on the two linear regulators. The controller 700 can detect the temperature of the switch Q1 and the switch Q2 respectively. In some embodiments, when the temperature of the switch Q1 is lower than the temperature of the switch Q2, in response to the temperature relationship, the controller 700 can reduce the gate drive voltage of the switch Q1 and increase the gate drive voltage of the switch Q2, thereby increasing the power loss of the switch Q1 and reducing the power loss of the switch Q2. On the other hand, when the temperature of the switch Q1 is higher than the temperature of the switch Q2, the controller 700 can reduce the gate drive voltage of the switch Q2 and increase the gate drive voltage of the switch Q1, thereby increasing the power loss of the switch Q2 and reducing the power loss of the switch Q1. By using the above control mechanism, a uniform temperature distribution can be achieved in the switch Q1 and the switch Q2.

[0061] In some embodiments, the first gate driver and the second gate driver are coordinated so that the switch Q1 and the switch Q2 are configured as a linear regulator in an alternating manner. For example, the controller 700 can detect the temperature of the switch Q1 and the switch Q2, respectively. When the temperature of the switch Q1 exceeds a predetermined temperature threshold, the controller 700 configures the switch Q1 as a normally-on switch and configures the switch Q2 as a linear regulator. Similarly, when the temperature of the switch Q2 exceeds a predetermined temperature threshold, the controller 700 configures the switch Q2 as a normally-on switch and configures the switch Q1 as a linear regulator. By using the above control mechanism, the switch Q1 and the switch Q2 are configured as a linear regulator in an alternating manner.

[0062] It should be noted that the controller 700 with five gate drivers is only used as an example and should not be overly interpreted as limiting the scope of the claims. Those skilled in the art will recognize that there may be many variations, substitutions and modifications to the various embodiments of the present disclosure. For example, the driving capability may be further improved by using an external gate driver.

[0063] Although the embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made to the embodiments of the present disclosure without departing from the spirit and scope of the disclosure as defined by the appended claims.

[0064] In addition, the scope of the present application is not limited to the specific embodiments of the processes, machines, manufactures, material compositions, devices, methods and steps described in the specification. As can be easily understood by those skilled in the art from this disclosure, processes, machines, manufactures, material compositions, devices, methods or steps having substantially the same functions or achieving substantially the same results as the corresponding embodiments described herein can be adopted according to the present disclosure, and these processes, machines, manufactures, material compositions, devices, methods or steps may be currently existing or developed in the future. Therefore, the appended claims are intended to include such processes, machines, manufactures, material compositions, devices, methods or steps within their scope.

Claims

1. A battery charging device, comprising: a first switch, a second switch, a third switch, and a fourth switch connected in series between an input voltage bus and ground, wherein a common node of the second switch and the third switch is configured to be coupled to a battery; a flying capacitor connected between a common node of the first switch and the second switch and a common node of the third switch and the fourth switch; as well as a controller configured to generate a gate drive signal to configure the first switch and the second switch as a linear regulator during charging of the battery, wherein the first switch is configured as a first linear regulator; The second switch is configured as a second linear regulator; The third switch is configured as a normally-off switch; as well as The fourth switch is configured as a normally-on switch.

2. The battery charging device according to claim 1, wherein: Configuring the first switch as the first linear regulator and configuring the second switch as the second linear regulator are performed simultaneously.

3. The battery charging device according to claim 1, wherein: Configuring the first switch as the first linear regulator and configuring the second switch as the second linear regulator are performed alternately.

4. The battery charging device according to claim 1, further comprising: A switch is connected between the input voltage bus and a power source, wherein the switch is configured to be fully turned on during charging of the battery.

5. A battery charging device, comprising: a first switch, a second switch, a third switch, and a fourth switch connected in series between an input voltage bus and ground, wherein a common node of the second switch and the third switch is configured to be coupled to a battery; a flying capacitor connected between a common node of the first switch and the second switch and a common node of the third switch and the fourth switch; as well as a controller configured to generate a gate drive signal to configure at least one of the first switch and the second switch as a linear regulator during charging of the battery, The controller is further configured to detect temperatures of the first switch and the second switch, and dynamically configure the first switch as a first linear regulator and the second switch as a second linear regulator based on the temperatures of the first switch and the second switch.

6. The battery charging device according to claim 5, further comprising: A switch is connected between the input voltage bus and a power source, wherein the switch is configured to be fully turned on during charging of the battery.

7. A method for charging a battery, comprising: A power converter is coupled to the battery, wherein the power converter comprises: a first switch, a second switch, a third switch, and a fourth switch connected in series between an input voltage bus and ground, wherein a common node of the second switch and the third switch is configured to be coupled to a battery; and a flying capacitor connected between a common node of the first switch and the second switch and a common node of the third switch and the fourth switch; and During the charging process of the battery, the first switch is configured as a first linear regulator, the second switch is configured as a second linear regulator, the third switch is configured as a normally-off switch, and the fourth switch is configured as a normally-on switch.

8. The method according to claim 7, further comprising: During the trickle charging stage and the pre-charging stage of the battery charging process, the first switch and the second switch are configured as a linear regulator to charge the battery.

9. The method according to claim 7, further comprising: In a small current portion of a constant voltage charging phase during the charging process of the battery, the first switch and the second switch are configured as a linear regulator to charge the battery.

10. The method according to claim 7, further comprising: At the end charging stage of the battery charging process, the first switch and the second switch are configured as a linear regulator to charge the battery.

11. The method according to claim 7, further comprising: During a fast charging phase of the battery, the power converter is configured to operate in a charge pump mode.

12. The method according to claim 11, wherein: The fast charging stage of the battery includes a large current part of a constant voltage charging stage and a constant current charging stage.

13. A method for charging a battery, comprising: A power converter is coupled to the battery, wherein the power converter comprises: a first switch, a second switch, a third switch, and a fourth switch connected in series between an input voltage bus and ground, wherein a common node of the second switch and the third switch is configured to be coupled to a battery; and a flying capacitor connected between a common node of the first switch and the second switch and a common node of the third switch and the fourth switch; and During the charging process of the battery, the temperatures of the first switch and the second switch are detected, and based on the temperatures of the first switch and the second switch, the first switch is dynamically configured as a first linear regulator and the second switch is dynamically configured as a second linear regulator.

14. A controller comprising: A plurality of gate drivers are configured to generate a plurality of gate drive signals to drive a switched capacitor power converter, wherein: The switched capacitor power converter is configured to charge a battery; and During the charging process of the battery, the gate drive signal is configured to cause at least one switch in the switched capacitor power converter to be configured as a linear regulator, The switched capacitor power converter comprises at least a first switch, a second switch, a third switch and a fourth switch connected in series between an input voltage bus and ground. The first switch is configured as a first linear regulator; The second switch is configured as a second linear regulator; The third switch is configured as a normally-off switch; and The fourth switch is configured as a normally-on switch.

15. The controller according to claim 14, wherein: The switched capacitor power converter comprises: the first switch, the second switch, the third switch, and the fourth switch connected in series between an input voltage bus and ground, wherein a common node of the second switch and the third switch is configured to be coupled to a battery; and A flying capacitor is connected between a common node between the first switch and the second switch and a common node between the third switch and the fourth switch.

16. A controller comprising: A plurality of gate drivers are configured to generate a plurality of gate drive signals to drive a switched capacitor power converter, wherein: The switched capacitor power converter is configured to charge a battery; and During the charging process of the battery, the gate drive signal is configured to cause at least one switch in the switched capacitor power converter to be configured as a linear regulator, The switched capacitor power converter includes at least a first switch and a second switch, and the controller is further configured to detect the temperatures of the first switch and the second switch, and based on the temperatures of the first switch and the second switch, dynamically configure the first switch as a first linear regulator and the second switch as a second linear regulator.

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