Mode switching control method for switched capacitor converter

Abstract

A method and apparatus for controlling mode conversion of a switched capacitor converter are provided. The method includes: configuring a switched capacitor converter to operate in a first fixed PWM mode, wherein in the first fixed PWM mode, the switched capacitor converter is configured to charge a battery coupled to an input terminal of the switched capacitor converter; configuring the switched capacitor converter to operate in a second fixed PWM mode, wherein in the second fixed PWM mode, the switched capacitor converter is configured to discharge the battery; and configuring the switched capacitor converter to operate in a skip mode, wherein the switched capacitor converter automatically converts between different modes based on a comparison between an output voltage of the switched capacitor converter and a plurality of predetermined voltage thresholds.

Description

Technical Field

[0001] The present invention relates to a battery charging device and control method, and in a specific embodiment, to a switched capacitor converter mode conversion control device and method. Background Art

[0002] With the further development of technology, various electronic devices such as mobile phones, tablet PCs, digital cameras, MP3 players and / or the like have become popular. Each portable device may employ a plurality of rechargeable battery cells. A plurality of rechargeable battery cells may be connected in series or in parallel to form a rechargeable battery pack for storing electrical energy.

[0003] A 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, thereby restoring the energy of the battery.

[0004] There can be a variety of power conversion topologies suitable for charging a battery. Depending on the topology, the power conversion topologies can be divided into three categories, namely, switching power converters, linear regulators, and switched capacitor power converters. Compared to other topologies, the switched capacitor converter is less complex because the switched capacitor converter is formed by multiple switches and flying capacitors. Therefore, the switched capacitor converter can provide a compact and efficient power supply for charging the battery.

[0005] In a dual-cell battery application, a bidirectional charge pump (e.g., a dual-phase switched capacitor converter) is used as a charger for charging the dual-cell battery. The switching charger and the bidirectional charge pump are coupled between the ac / dc adapter and the dual-cell battery. When the ac / dc adapter is present and the dual-cell battery is not fully charged, the bidirectional charge pump operates in a 1:2 charging mode. When the ac / dc adapter is not present or the ac / dc adapter is present but stops charging the dual-cell battery, the bidirectional charge pump operates in a 2:1 discharging mode to power the system load.

[0006] In 1:2 charging mode, the bidirectional charge pump is configured to operate in fixed pulse width modulation (PWM) mode to stably charge the battery. In 2:1 discharge mode, the bidirectional charge pump is configured to operate in skip mode under light load conditions to achieve better conversion efficiency and extend battery life. In 2:1 discharge mode, when the system load is heavy, the bidirectional charge pump can leave skip mode and enter fixed PWM mode to reduce output ripple.

[0007] As described above, a bidirectional charge pump is capable of operating in two different modes including a 1:2 charging mode and a 2:1 discharging mode. The 2:1 discharging mode also includes a skip mode and a fixed PWM mode. It is desirable to configure a bidirectional charge pump to have seamless transitions between different operating modes. The present invention addresses this need. Summary of the invention

[0008] These and other problems are generally solved or circumvented, and technical advantages are generally achieved, by preferred embodiments of the present disclosure, which provide a switched capacitor converter mode transition control apparatus and method.

[0009] According to one embodiment, a method includes: configuring a switched capacitor converter to operate in a first fixed PWM mode, wherein, in the first fixed PWM mode, the switched capacitor converter is configured to charge a battery coupled to an input terminal of the switched capacitor converter; configuring the switched capacitor converter to operate in a second fixed PWM mode, wherein, in the second fixed PWM mode, the switched capacitor converter is configured to discharge the battery; and configuring the switched capacitor converter to operate in a skip mode, wherein the switched capacitor converter automatically switches between different modes based on a comparison between an output voltage of the switched capacitor converter and a plurality of predetermined voltage thresholds.

[0010] According to another embodiment, a method includes: coupling an input of a switched capacitor power converter to a battery, and coupling an output of the switched capacitor power converter to a system load and a charger; configuring the switched capacitor converter to operate in a 1:2 fixed PWM mode to charge the battery; configuring the switched capacitor converter to operate in a 2:1 fixed PWM mode to discharge the battery; and configuring the switched capacitor converter to operate in a 2:1 skip mode under light load operating conditions, wherein the switched capacitor converter automatically switches between different modes based on a comparison between an output voltage of the switched capacitor converter and a plurality of predetermined voltage thresholds.

[0011] According to yet another embodiment, a controller includes: a first comparator configured to compare an output voltage of a switched capacitor power converter with a first fixed PWM mode threshold voltage, wherein the first fixed PWM mode threshold voltage is greater than half of an input voltage of the switched capacitor power converter; a second comparator configured to compare the output voltage of the switched capacitor power converter with a skip mode threshold voltage; a third comparator configured to compare the output voltage of the switched capacitor power converter with a threshold voltage for starting the skip mode; a fourth comparator configured to compare the output voltage of the switched capacitor power converter with a second fixed PWM mode threshold voltage, wherein the second fixed PWM mode threshold voltage is less than half of the input voltage of the switched capacitor power converter; and a fifth comparator configured to compare a current flowing through the switched capacitor power converter with a predetermined sink current to determine whether the switched capacitor power converter enters the skip mode under light load operating conditions.

[0012] The features and technical advantages of the present disclosure have been outlined quite broadly above so that the detailed description of the disclosure below may be better understood. Additional features and advantages of the present disclosure will be described below, which form the subject matter of the claims of the present disclosure. It will be appreciated by those skilled in the art that the disclosed concepts and specific embodiments may be easily used as a basis for modifying or designing other structures or processes for achieving the same purpose as the present disclosure. It will also be appreciated by those skilled in the art that such equivalent structures do not depart from the spirit and scope of the present invention as described in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0014] Figure 1 A schematic diagram showing a battery charging system according to various embodiments of the present disclosure is shown;

[0015] Figure 2 A method for driving a vehicle according to various embodiments of the present disclosure is shown. Figure 1 A controller for switches of the dual-phase switched capacitor power converter shown;

[0016] Figure 3 The various embodiments of the present disclosure are shown Figure 2 A schematic diagram of a mode conversion control unit shown;

[0017] Figure 4-Figure 5 A timing diagram for controlling a two-phase switched capacitor power converter operating in different operating modes according to various embodiments of the present disclosure is shown;

[0018] Figure 6 The method for controlling the Figure 1 A state machine for mode conversion of a dual-phase switched capacitor power converter as shown; and

[0019] Figure 7 The control according to various embodiments of the present disclosure is shown Figure 1 Flowchart of the battery charging system shown.

[0020] Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated.The figures are drawn to clearly illustrate the relevant aspects of the various embodiments and are not necessarily drawn to scale. DETAILED DESCRIPTION

[0021] The manufacture and use of the currently preferred embodiments are discussed in detail below. However, it should be understood that the present disclosure provides many applicable inventive concepts that can be implemented in a variety of specific contexts. The specific embodiments discussed only illustrate specific ways to make and use the present disclosure and do not limit the scope of the present disclosure.

[0022] The present disclosure will be described in a specific context with respect to preferred embodiments, namely a switched capacitor converter mode conversion control device and method. However, the present disclosure may also be applied to various power converters. In the following, various embodiments will be explained in detail with reference to the accompanying drawings.

[0023] Figure 1 1 shows a schematic diagram of a battery charging system according to various embodiments of the present disclosure. The battery charging system includes a dual-phase switched capacitor power converter 100 and a power management integrated circuit (PMIC) 102. Figure 1 As shown, the input of the two-phase switched capacitor power converter 100 is connected to a battery. The input voltage bus to which the two-phase switched capacitor power converter 100 and the battery are coupled is denoted as VIN.

[0024] In some embodiments, the battery can be implemented as a multi-core battery. In the present disclosure, the battery is such as Figure 1 Dual-cell battery shown.

[0025] The output of the dual-phase switched capacitor power converter 100 is connected to an output voltage bus Vo. The output capacitor Co is connected between Vo and ground. The output voltage bus Vo is connected to a switching charger of the PMIC 102 via a switch S1. In some embodiments, S1 is a power switch. Figure 1As shown, the output of the switching charger of the PMIC 102 and the system load VSYS are also connected together. The switching charger of the PMIC 102 can be implemented as any suitable charger, such as a buck switching charger. The input of the buck switching charger can be coupled to a power source such as an ac / dc adapter. The output of the buck switching charger is connected to Vo through S1. When the ac / dc adapter is connected to the battery charging system, the PMIC 102 (e.g., buck switching charger) is configured to provide power for charging the battery through the dual-phase switched capacitor power converter 100.

[0026] The dual-phase switched capacitor power converter 100 includes two branches. The first branch 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 VIN and ground. A first flying capacitor CF1 is connected between a common node of Q1 and Q2 and a common node of Q3 and Q4. The second branch includes a fifth switch Q5, a sixth switch Q6, a seventh switch Q7, and an eighth switch Q8 connected in series between an input voltage bus VIN and ground. A second flying capacitor CF2 is connected between a common node of Q5 and Q6 and a common node of Q7 and Q8. Figure 1 As shown, the common node of Q2 and Q3 is connected to the output voltage bus Vo. The common node of Q6 and Q7 is also connected to the output voltage bus Vo. Throughout the description, the two-phase switched capacitor power converter 100 may be alternatively referred to as a switched capacitor converter.

[0027] In operation, the operating principle of the first branch is similar to that of the second branch, except that the driving signal of the first branch (e.g., Q1) and the driving signal of the second branch (e.g., Q5) are 180 degrees out of phase with each other. For simplicity, only the operating principle of the first branch is described in detail below.

[0028] In operation, the first branch of the switched capacitor converter 100 is configured to operate in two different phases. During 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 VIN and Vo. The first conductive path is formed by switch Q1, the first flying capacitor CF1, and switch Q3. Current flows from VIN to Vo through the first conductive path. During the first phase, the first flying capacitor CF1 is charged, and energy is stored in the first flying capacitor CF1 accordingly.

[0029] During the second phase, 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, the first flying capacitor CF1, and switch Q2. During the second phase, the current discharges the first flying capacitor CF1, and the energy stored in the first flying capacitor CF1 is reduced accordingly.

[0030] The above operating principle is based on the 2:1 fixed PWM mode. The two phases of the 1:2 fixed PWM mode are similar to the two phases of the 2:1 fixed PWM mode, so they will not be discussed here to avoid repetition.

[0031] According to one embodiment, Figure 1 The switches (e.g., switches Q1-Q8) can be metal oxide semiconductor field effect transistor (MOSFET) devices, bipolar junction transistor (BJT) devices, super junction transistor (SJT) devices, insulated gate bipolar transistor (IGBT) devices and / or gallium nitride (GaN) based power devices, etc.

[0032] It should be noted that although Figure 1 The switches Q1-Q8 are shown to be implemented as a single n-type transistor, but those skilled in the art will recognize that there may be many variations, modifications, and substitutions. For example, at least some of the switches Q1-Q8 may be implemented as p-type transistors, depending on different applications and design requirements. In addition, Figure 1 Each switch shown in can be implemented as a plurality of 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).

[0033] Controller (not shown, but in Figure 2 ) is configured to generate gate drive signals for switches Q1-Q8. In addition, the controller is configured to detect multiple operating parameters, including an input voltage on the input voltage bus VIN, an output voltage on the output voltage bus Vo, a current flowing through the first branch, and a current flowing through the second branch. Based on the detected operating parameters, the controller can determine the operating mode of the switched capacitor converter 100.

[0034] The operating modes of the switched capacitor converter 100 include a 1:2 fixed PWM mode, a 2:1 fixed PWM mode, and a 2:1 skip mode. The switched capacitor converter 100 is used as a bidirectional charge pump. When a power source is connected to the output voltage bus Vo, the switched capacitor converter 100 converts the voltage on Vo to a higher voltage. In particular, the output voltage (the voltage on Vo) is twice the input voltage (the voltage on VIN). In this configuration, the switched capacitor converter 100 operates in a 1:2 fixed PWM mode. In the present disclosure, when a power source (e.g., an ac / dc adapter) is connected to Vo via a PMIC 102, the switched capacitor converter 100 is configured to operate in a 1:2 fixed PWM mode to charge the battery.

[0035] On the other hand, when the battery is used as a power source, the switched capacitor converter 100 converts the voltage on VIN to a lower voltage. In particular, the output voltage (the voltage on Vo) is equal to half the input voltage (VIN / 2). In this configuration, the switched capacitor converter 100 operates in a 2:1 fixed PWM mode. In the present disclosure, when a power source (e.g., an ac / dc adapter) is not connected to the battery charging system, the switched capacitor converter 100 is configured to operate in a 2:1 fixed PWM mode to power the system load.

[0036] In addition, the switched capacitor converter 100 can be operated in a 2:1 skip mode to reduce switching losses. In the 2:1 fixed PWM mode, the switched capacitor converter 100 can be operated at a fixed switching frequency (e.g., 500KHz). In order to reduce switching losses under light load operating conditions, the controller can skip unnecessary switching clock pulses while regulating the output voltage. For example, in the skip mode, when the output voltage drops below a predetermined threshold, a new cycle is started. As a result of skipping unnecessary switching clock pulses, the switching frequency of the skip mode is lower than the fixed switching frequency.

[0037] It should be noted that Figure 1 The battery charging system shown in is provided for illustration purposes only and is provided only as an example of functionality that may be included in a battery charging system. One of ordinary skill in the art will recognize that the battery charging system may include other necessary components. For example, to protect the battery, an isolation switch (not shown) may be connected between the battery and a power source (e.g., a direct charging adapter) that powers the battery charging. The isolation switch consists of two switches connected back to back. The isolation switch can provide reverse blocking capability to isolate the battery from the power source.

[0038] In operation, the switched capacitor converter 100 is configured to operate in a first fixed PWM mode. The first fixed PWM mode is a 1:2 fixed PWM mode. In the first fixed PWM mode, the switched capacitor converter 100 is configured to charge a battery coupled to VIN.

[0039] In operation, the switched capacitor converter 100 is configured to operate in a second fixed PWM mode. The second fixed PWM mode is a 2:1 fixed PWM mode. In the second fixed PWM mode, the switched capacitor converter 100 is configured to discharge the battery.

[0040] In operation, the switched capacitor converter 100 is configured to operate in a skip mode. The skip mode is a 2:1 skip mode. In particular, the switched capacitor converter 100 operates in the 2:1 skip mode under light load operating conditions.

[0041] In operation, the switched capacitor converter 100 can automatically switch between different modes based on a comparison between the output voltage of the switched capacitor converter and a plurality of predetermined voltage thresholds. The detailed operating principle of the switched capacitor converter 100 will be described below with reference to Figure 2-Figure 6 Have a discussion.

[0042] Figure 2 A method for driving a vehicle according to various embodiments of the present disclosure is shown. Figure 1 The controller of the switches of the dual-phase switched capacitor power converter shown in the figure. The controller includes a switched capacitor control unit 202 and a mode conversion control unit 204. The mode conversion control unit 204 is a mode conversion control device. The mode conversion control unit 204 is configured to detect multiple operating parameters, including a current ICH1 flowing through the first branch of the switched capacitor converter 100, a current ICH2 flowing through the second branch of the switched capacitor converter 100, an output voltage Vo, and an input voltage VIN. Based on the detected operating parameters, the mode conversion control unit 204 generates a mode conversion command fed to the switched capacitor control unit 202. Based on the mode conversion command, the switched capacitor control unit 202 changes the operating mode of the switched capacitor converter accordingly. The following will refer to Figure 3 The detailed structure and operation principle of the mode switching control unit 204 are discussed.

[0043] The switched capacitor control unit 202 includes a plurality of gate drivers configured to generate a plurality of gate drive signals for driving the switched capacitor power converter. The first gate driver is configured to generate a first gate drive signal applied to the gate of Q1. The second gate driver is configured to generate a second gate drive signal applied to the gate of Q2. The third gate driver is configured to generate a third gate drive signal applied to the gate of Q3. The fourth gate driver is configured to generate a fourth gate drive signal applied to the gate of Q4. The fifth gate driver is configured to generate a fifth gate drive signal applied to the gate of Q5. The sixth gate driver is configured to generate a sixth gate drive signal applied to the gate of Q6. The seventh gate driver is configured to generate a seventh gate drive signal applied to the gate of Q7. The eighth gate driver is configured to generate an eighth gate drive signal applied to the gate of Q8.

[0044] The controller may also include a predetermined current sink. The current sink provides a sink current applied to the output voltage bus Vo. In other words, the current sink acts as a virtual load. In some embodiments, the current sink is about 50mA. In order to reduce unnecessary power loss, the current sink is enabled for about 20 microseconds in every millisecond. It should be noted that the numbers used in the previous examples (50mA and 20 microseconds) are purely selected for demonstration purposes and are not intended to limit the various embodiments of the present disclosure to any particular numbers.

[0045] Figure 3 The various embodiments of the present disclosure are shown Figure 2 The mode conversion control unit 204 includes a summing unit 302 , an integrator 304 , and a plurality of comparators 312 , 314 , 316 , 318 , and 306 .

[0046] The first comparator 312 is configured to compare the output voltage VO of the switched capacitor converter with CCM_H. In some embodiments, CCM_H is a first fixed PWM mode threshold voltage. Once Vo exceeds CCM_H, the first comparator 312 generates a command to configure the switched capacitor converter to enter a 1:2 fixed PWM mode.

[0047] The second comparator 314 is configured to compare the output voltage Vo of the switched capacitor converter with DCM_H. In some embodiments, DCM_H is a skip mode threshold voltage. Once Vo exceeds DCM_H, the second comparator 314 generates a command to configure the switched capacitor converter to leave the 2:1 fixed PWM mode and enter the 2:1 skip mode.

[0048] The third comparator 316 is configured to compare the output voltage Vo of the switched capacitor converter with DCM_L. In some embodiments, DCM_L is a threshold voltage for starting a new cycle in the skip mode. Once Vo drops below DCM_L, the third comparator 316 generates a command to start a new cycle in the skip mode.

[0049] The fourth comparator 318 is configured to compare the output voltage Vo of the switched capacitor converter with CCM_L. In some embodiments, CCM_L is a second fixed PWM mode threshold voltage. The second fixed PWM mode threshold voltage is lower than the first fixed PWM mode threshold voltage. Once Vo drops below CCM_L, the fourth comparator 318 generates a command to configure the switched capacitor converter to leave the 2:1 skip mode and enter the 2:1 fixed PWM mode.

[0050] The current ICH1 of the first branch and the current ICH2 of the second branch are added together in the summing unit 302. The result generated by the summing unit 302 represents the current flowing through the switched capacitor converter 100. Figure 3 As shown, the result of the summing unit 302 is fed into the integrator 304. The integrator 304 is used to filter out unwanted noise signals from the current signals (ICH1 and ICH2) and provide appropriate delay so that the switched capacitor converter 100 can reliably enter the skip mode.

[0051] The fifth comparator 306 is configured to compare the current flowing through the switched capacitor converter with FWD_DET. In some embodiments, FWD_DET is a threshold for entering the skip mode under light load operating conditions. Figure 2 As described above, the dummy load (e.g., 50 mA) generates a current flowing through the switched capacitor converter 100. By comparing the current flowing through the switched capacitor converter 100 with FWD_DET, the fifth comparator 306 can determine whether the external power supply is available. More specifically, when the detected current is equal to the current of the dummy load, the external power supply is not available. In response to the system configuration, the controller configures the switched capacitor converter 100 to leave the 1:2 fixed PWM mode and enter the 2:1 skip mode.

[0052] It should be noted that Figure 3The schematic diagram shown in is only an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize many variations, substitutions and modifications. For example, Vo can be directly compared with half of VIN (VIN / 2). The difference between Vo and VIN / 2 is compared with four thresholds. The first threshold is equal to the difference between CCM_H and VIN / 2. The first threshold is used to determine whether the switched capacitor converter enters a fixed PWM mode. The second threshold is equal to the difference between DCM_H and VIN / 2. The second threshold is used to determine whether the switched capacitor converter enters a jump mode. The third threshold is equal to the difference between DCM_L and VIN / 2. The third threshold is used to start a new cycle in the jump mode. The fourth threshold is equal to the difference between CCM_L and VIN / 2. The fourth threshold is used to determine whether the switched capacitor converter enters a fixed PWM mode.

[0053] have Figure 3 An advantageous feature of the illustrated mode conversion control unit 204 is that the switched capacitor converter 100 is capable of automatically converting between different operating modes. In conventional battery charging systems, an application processor is used to monitor system operating parameters. Based on the detected parameters, the application processor sends appropriate control signals to control the operating mode of the switched capacitor converter. The control configuration of the conventional battery charging system increases the complexity of the control system. In addition, due to communication delays, the control signal from the application processor is not fast enough. The slow response can cause a slow mode conversion from the jump mode to the fixed PWM mode. In the present disclosure, a mode conversion control signal is generated in the controller. The mode conversion command is directly applied to the gate driver. The mode conversion can be automatically performed in the controller. This control configuration can simplify the system control design so that there is a seamless conversion between different operating modes, thereby improving the reliability of the mode conversion.

[0054] Figure 4-Figure 5 A timing diagram for controlling a two-phase switched capacitor power converter operating in different operating modes according to various embodiments of the present disclosure is shown. Figure 4-Figure 5 The horizontal axis represents the time interval. Figure 4-Figure 5 There may be five dotted lines in FIG. The first dotted line represents the first voltage threshold CCM_H. In some embodiments, CCM_H is the first fixed PWM mode voltage threshold. The second dotted line represents half of the input voltage (VIN / 2). The third dotted line represents the second voltage threshold DCM_H. In some embodiments, DCM_H is the skip mode voltage threshold. The fourth dotted line represents the third voltage threshold DCM_L. In some embodiments, DCM_L is the voltage threshold for starting a new cycle in skip mode. The fifth dotted line represents the fourth voltage threshold CCM_L. In some embodiments, CCM_L is the second fixed PWM mode voltage threshold.

[0055] like Figure 4 As shown, the first voltage threshold CCM_H is higher than VIN / 2. The second voltage threshold DCM_H is lower than VIN / 2. The third voltage threshold DCM_L is lower than the second voltage threshold DCM_H. The fourth voltage threshold CCM_L is lower than the third voltage threshold DCM_L. It should be noted that these four thresholds are not fixed. The values ​​of these four thresholds can vary in proportion to the input voltage VIN.

[0056] In the first duration T1, the switched capacitor power converter operates in the 2:1 skip mode. In response to the load increase, the output voltage Vo decreases. Once Vo drops below the fourth voltage threshold CCM_L, the switched capacitor converter 100 is configured to leave the 2:1 skip mode and enter the 2:1 fixed PWM mode.

[0057] In the second duration T2, the switched capacitor converter operates in a 2:1 fixed PWM mode. When the ac / dc adapter is plugged in, the PMIC 102 starts to supply power to Vo. In response to the system configuration change, Vo increases in a linear manner at the end of T2, as shown in FIG. Figure 4 shown.

[0058] In the third duration T3, once Vo exceeds the first voltage threshold CCM_H, the controller configures the switched capacitor converter 100 to leave the 2:1 fixed PWM mode and enter the 1:2 fixed PWM mode. In the 1:2 fixed PWM mode, the switched capacitor converter 100 is configured to charge the battery.

[0059] At the end of T3, PMIC 102 stops supplying power to Vo. The output voltage Vo decreases accordingly, as shown in FIG. Figure 4 shown.

[0060] In the fourth duration T4, the output voltage Vo is maintained at VIN / 2. As described above, a current sink of approximately 50 mA is applied to the output of the switched capacitor converter 100. The controller is capable of detecting the current flowing from the input to the output of the switched capacitor converter. When the current is detected to be equal to a predetermined value (e.g., 50 mA), the controller configures the switched capacitor converter 100 to leave the 1:2 fixed PWM mode and enter the skip mode at the end of T4. In the skip mode, since Vo is higher than DCM_H, the controller immediately stops switching.

[0061] In the fifth time period T5, after the controller stops switching, the output voltage Vo decreases. Once the output voltage Vo reaches DCM_L, a new cycle begins, as shown in FIG. Figure 5 shown.

[0062] In the sixth duration T6, the switched capacitor converter operates in the 2:1 skip mode. At the end of T6, the ac / dc adapter is plugged in and the PMIC 102 starts to power Vo. In response to the system configuration change, Vo increases in a linear manner at the end of T6 and at the beginning of T7. Once Vo exceeds CCM_H, the controller configures the switched capacitor converter 100 to leave the 2:1 skip mode and enter the 1:2 fixed PWM mode.

[0063] In the seventh duration T7, the switched capacitor converter 100 operates in the 1:2 fixed PWM mode to charge the battery. In the eighth duration T8, the battery is almost fully charged. The current flowing from the PMIC 102 to the battery decreases. In response to the reduced current, the voltage difference between Vo and VIN / 2 becomes smaller, as shown in FIG. Figure 5 It should be noted that before the battery is fully charged, the charging current still flows from Vo to VIN.

[0064] At the end of T8, the battery is fully charged. In the ninth duration T9, the output voltage Vo of the switched capacitor converter 100 is maintained at VIN / 2. As described above, a current sink of approximately 50mA is applied to the output of the switched capacitor converter. The controller is able to detect a current flowing from the input of the switched capacitor converter to the output, which is equal to the current from the current sink. Upon detecting this current, the controller configures the switched capacitor converter 100 to leave the 1:2 fixed PWM mode and enter the jump mode at the beginning of the tenth duration T10. In the jump mode, since Vo is higher than DCM_H, the controller immediately stops switching. In T10, once Vo drops to DCM_L, the controller starts a new cycle to charge Vo.

[0065] Figure 6 The method for controlling the Figure 1 The state machine of the mode conversion of the dual-phase switched capacitor power converter is shown. The state machine includes three states, namely, 1:2 fixed PWM state 602, 2:1 fixed PWM state 604 and 2:1 skip state 606. 1:2 fixed PWM state 602 corresponds to 1:2 fixed PWM mode. 2:1 fixed PWM state 604 corresponds to 2:1 fixed PWM mode. 2:1 skip state 606 corresponds to 2:1 skip mode.

[0066] As used herein, a state machine is defined as a machine that can be in one of a plurality of states (e.g., states 602, 604, and 606), the machine being in one state at a time, with the ability to change (e.g., transition) from one state to another upon a triggering event of a condition. Thus, such a state machine may be defined by its states and the triggering conditions for transitioning between two states. Figure 6In the state machine shown, the events that cause transitions from one state to another are generated by Figure 6 The old state is shown indicated by an arrow pointing to the new state.

[0067] Figure 6 The state machine shown in allows state transitions between the 1:2 fixed PWM state 602 and the 2:1 fixed PWM state 604 , between the 2:1 fixed PWM state 604 and the 2:1 skip state 606 , and between the 2:1 skip state 606 and the 1:2 fixed PWM state 602 .

[0068] Based on the input voltage and output voltage of the switched capacitor power converter, a controller (not shown but Figure 2 ) can determine the operating mode of the switched capacitor power converter 100. If the switched capacitor power converter 100 is ready for the 1:2 fixed PWM mode, the controller generates a "1:2 fixed PWM" command. Similarly, if the switched capacitor power converter 100 is ready for the 2:1 fixed PWM mode, the controller generates a "2:1 fixed PWM" command. In addition, if the switched capacitor power converter 100 is ready for the 2:1 skip mode, the controller generates a "2:1 skip" command.

[0069] In the mode transition from the 1:2 fixed PWM state 602 to the 2:1 fixed PWM state 604, the transition from state 602 to state 604 is triggered if the following conditions are met: Vo is less than Figure 5-Figure 6 The predetermined threshold CCM_L shown in FIG. The predetermined threshold CCM_L is a predetermined voltage. In some embodiments, the predetermined voltage (CCM_L) can vary in response to different input voltages. In the mode transition from the 2:1 fixed PWM state 604 to the 1:2 fixed PWM state 602, the transition from state 604 to state 602 is triggered if the following conditions are met: Vo is greater than Figure 5-Figure 6 The predetermined threshold CCM_H is shown in FIG. The predetermined threshold CCM_H is a predetermined voltage. In some embodiments, the predetermined voltage (CCM_H) may vary in response to different input voltages.

[0070] In the mode transition from the 2:1 fixed PWM state 604 to the 2:1 skipping state 606, the transition from state 604 to state 606 is triggered if the following conditions are met: Vo is greater than Figure 5-Figure 6 The predetermined threshold DCM_H is a predetermined voltage. In some embodiments, the predetermined voltage (DCM_H) may vary in response to different input voltages. In the mode transition from the 2:1 jump state 606 to the 2:1 fixed PWM state 604, the transition from state 606 to state 604 is triggered if the following conditions are met: Vo is less than Figure 5-Figure 6 The predetermined threshold CCM_L shown in .

[0071] In the mode transition from the 2:1 skip state 606 to the 1:2 fixed PWM state 602, the transition from state 606 to state 602 is triggered if the following conditions are met: Vo is greater than Figure 5-Figure 6 In the mode transition from the 1:2 fixed PWM state 602 to the skip state 606, the transition from state 602 to state 606 is triggered if the following conditions are met: the controller detects a current flowing from the input terminal to the output terminal of the switched capacitor converter. The current is equal to a predetermined current sink (e.g., 50 mA).

[0072] Figure 7 The control according to various embodiments of the present disclosure is shown Figure 1 Flowchart of the battery charging system shown. Figure 7 The flowchart shown is merely an example, which should not unduly limit the scope of the claims. Those of ordinary skill in the art will recognize many variations, substitutions, and modifications. For example, the present invention may be added, removed, replaced, rearranged, and repeated. Figure 7 The various steps shown in .

[0073] Back to Figure 1 , the switched capacitor power converter is a two-phase switched capacitor converter. The input of the two-phase switched capacitor converter is coupled to a battery such as a two-cell battery. The output of the two-phase switched capacitor converter is coupled to a PMIC and a system load.

[0074] At step 702, the switched capacitor converter is configured to operate in a first fixed PWM mode. In the first fixed PWM mode, the switched capacitor converter is configured to charge a battery coupled to an input terminal of the switched capacitor converter.

[0075] At step 704, the switched capacitor converter is configured to operate in a second fixed PWM mode. In the second fixed PWM mode, the switched capacitor converter is configured to discharge the battery.

[0076] At step 706, the switched capacitor converter is configured to operate in a skip mode. The switched capacitor converter automatically switches between different modes based on a comparison between an output voltage of the switched capacitor converter and a plurality of predetermined voltage thresholds.

[0077] Return to reference Figure 6(From state 606 to state 604), the method further includes: after the output voltage of the switched capacitor converter drops below a fourth voltage threshold, configuring the switched capacitor converter to leave the skip mode and enter a second fixed PWM mode. The second fixed PWM mode is a 2:1 fixed PWM mode, and the skip mode is a 2:1 skip mode.

[0078] Return to reference Figure 6 (From state 604 to state 602), the method further includes: after the output voltage of the switched capacitor converter exceeds the first voltage threshold, configuring the switched capacitor converter to leave the second fixed PWM mode and enter the first fixed PWM mode. The first fixed PWM mode is a 1:2 fixed PWM mode, and the second fixed PWM mode is a 2:1 fixed PWM mode.

[0079] Return to reference Figure 6 (From state 606 to state 602), the method further includes: after the output voltage of the switched capacitor converter exceeds the first voltage threshold, configuring the switched capacitor converter to leave the skip mode and enter a first fixed PWM mode. The first fixed PWM mode is a 1:2 fixed PWM mode, and the skip mode is a 2:1 skip mode.

[0080] Return to reference Figure 6 (From state 602 to state 604), the method further includes: after the output voltage of the switched capacitor converter drops below a fourth voltage threshold, configuring the switched capacitor converter to leave the first fixed PWM mode and enter a second fixed PWM mode. The first fixed PWM mode is a 1:2 fixed PWM mode, and the second fixed PWM mode is a 2:1 fixed PWM mode.

[0081] Return to reference Figure 6 (From state 604 to state 606), the method further includes: after the output voltage of the switched capacitor converter exceeds the second voltage threshold, configuring the switched capacitor converter to leave the second fixed PWM mode and enter the skip mode. The second fixed PWM mode is a 2:1 fixed PWM mode, and the skip mode is a 2:1 skip mode.

[0082] Return to reference Figure 6 (From state 602 to state 606), the method further includes: after the output voltage of the switched capacitor converter is maintained at half of the input voltage and the current flowing through the switched capacitor converter is equal to the predetermined sink current, configuring the switched capacitor converter to leave the first fixed PWM mode and enter the skip mode. The first fixed PWM mode is a 1:2 fixed PWM mode, and the skip mode is a 2:1 skip mode.

[0083] Return to reference Figure 4The method further comprises: in response to the load current increasing, configuring the switched capacitor converter to leave the 2:1 skip mode and enter the 2:1 fixed PWM mode by comparing the output voltage of the switched capacitor converter with a first fixed PWM mode voltage threshold value. The first fixed PWM mode voltage threshold value is less than half of the input voltage of the switched capacitor converter.

[0084] Return to reference Figure 4 The method further comprises: after the charger starts to supply power to the output terminal of the switched capacitor converter, configuring the switched capacitor converter to leave the 2:1 fixed PWM mode and enter the 1:2 fixed PWM mode by comparing the output voltage of the switched capacitor converter with a second fixed PWM mode voltage threshold value, wherein the second fixed PWM mode voltage threshold value is greater than half of the input voltage of the switched capacitor converter.

[0085] Refer to Figure 4 T4 and T5 of the method further include: after the charger stops supplying power to the output end of the switched capacitor converter and the output voltage of the switched capacitor converter is maintained at half of the input voltage of the switched capacitor converter, when it is detected that the current flowing through the switched capacitor converter is equal to a predetermined sink current, configuring the switched capacitor converter to leave the 1:2 fixed PWM mode and enter the 2:1 skip mode.

[0086] Return to reference Figure 5 The method further comprises configuring the switched capacitor converter to leave the 2:1 skip mode and enter the 1:2 fixed PWM mode by comparing the output voltage of the switched capacitor converter with a second fixed PWM mode voltage threshold after the charger starts to supply power to the output terminal of the switched capacitor converter. The second fixed PWM mode voltage threshold is greater than half of the input voltage of the switched capacitor converter.

[0087] Return to reference Figure 5 T9 and T10, the method also includes: after the battery has been fully charged and the output voltage of the switched capacitor converter is maintained at half of the input voltage of the switched capacitor converter, when it is detected that the current flowing through the switched capacitor converter is equal to a predetermined sink current, configuring the switched capacitor converter to leave the 1:2 fixed PWM mode and enter the 2:1 skip mode.

[0088] Although the embodiments of the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.

[0089] In addition, the scope of the present application is not limited to the specific embodiments of the processes, machines, manufactures, compositions of matter, devices, methods, and steps described in the specification. As will be readily appreciated by those of ordinary skill in the art from the disclosure of the present disclosure, processes, machines, manufactures, compositions of matter, devices, methods, or steps currently existing or later developed that perform substantially the same functions as the corresponding embodiments described herein or achieve substantially the same results as the corresponding embodiments described herein may be utilized in accordance with the present disclosure. Therefore, the appended claims are intended to include such processes, machines, manufactures, compositions of matter, devices, methods, or steps within their scope.

Claims

1. A method for controlling a switched capacitor converter, comprising: configuring a switched capacitor converter to operate in a first fixed PWM mode, wherein in the first fixed PWM mode, the switched capacitor converter is configured to charge a battery coupled to an input terminal of the switched capacitor converter; configuring the switched capacitor converter to operate in a second fixed PWM mode, wherein in the second fixed PWM mode, the switched capacitor converter is configured to discharge the battery; and The switched capacitor converter is configured to operate in a skip mode, wherein the switched capacitor converter automatically switches between different modes based on a comparison between an output voltage of the switched capacitor converter and a plurality of predetermined voltage thresholds, the automatic switching comprising directly switching between any two of the first fixed PWM mode, the second fixed PWM mode, and the skip mode.

2. The method of claim 1, wherein: The first fixed PWM mode is a 1:2 fixed PWM mode; The second fixed PWM mode is a 2:1 fixed PWM mode; and The skip mode is a 2:1 skip mode.

3. The method of claim 1, wherein: The switched capacitor converter comprises: A first switch, a second switch, a third switch and a fourth switch, wherein the first switch, the second switch, the third switch and the fourth switch are connected in series between the input terminal of the switched capacitor converter and the ground; a first 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; a fifth switch, a sixth switch, a seventh switch and an eighth switch, wherein the fifth switch, the sixth switch, the seventh switch and the eighth switch are connected in series between the input terminal of the switched capacitor converter and ground; and a second flying capacitor, wherein the second flying capacitor is connected between a common node of the fifth switch and the sixth switch and a common node of the seventh switch and the eighth switch, and wherein the common node of the second switch and the third switch is connected to a common node of the sixth switch and the seventh switch and is also connected to an output terminal of the switched capacitor converter.

4. The method of claim 1, wherein: The plurality of predetermined voltage thresholds include: a first voltage threshold, the first voltage threshold being higher than half of an input voltage of the switched capacitor converter; a second voltage threshold, the second voltage threshold being lower than half of the input voltage of the switched capacitor converter; a third voltage threshold, the third voltage threshold being lower than the second voltage threshold; and A fourth voltage threshold, wherein the fourth voltage threshold is lower than the third voltage threshold.

5. The method of claim 4, further comprising: After the output voltage of the switched capacitor converter drops below the fourth voltage threshold, the switched capacitor converter is configured to leave the skip mode and enter the second fixed PWM mode, wherein the second fixed PWM mode is a 2:1 fixed PWM mode and the skip mode is a 2:1 skip mode.

6. The method of claim 4, further comprising: After the output voltage of the switched capacitor converter exceeds the first voltage threshold, the switched capacitor converter is configured to leave the second fixed PWM mode and enter the first fixed PWM mode, wherein the first fixed PWM mode is a 1:2 fixed PWM mode and the second fixed PWM mode is a 2:1 fixed PWM mode.

7. The method of claim 4, further comprising: After the output voltage of the switched capacitor converter exceeds the first voltage threshold, the switched capacitor converter is configured to leave the skip mode and enter the first fixed PWM mode, wherein the first fixed PWM mode is a 1:2 fixed PWM mode and the skip mode is a 2:1 skip mode.

8. The method of claim 4, further comprising: After the output voltage of the switched capacitor converter drops below the fourth voltage threshold, the switched capacitor converter is configured to leave the first fixed PWM mode and enter the second fixed PWM mode, wherein the first fixed PWM mode is a 1:2 fixed PWM mode and the second fixed PWM mode is a 2:1 fixed PWM mode.

9. The method of claim 4, further comprising: After the output voltage of the switched capacitor converter exceeds the second voltage threshold, the switched capacitor converter is configured to leave the second fixed PWM mode and enter the skip mode, wherein the second fixed PWM mode is a 2:1 fixed PWM mode and the skip mode is a 2:1 skip mode.

10. The method of claim 4, further comprising: After the output voltage of the switched capacitor converter stays at half of the input voltage and the current flowing through the switched capacitor converter is equal to a predetermined sink current, the switched capacitor converter is configured to leave the first fixed PWM mode and enter the skip mode, wherein the first fixed PWM mode is a 1:2 fixed PWM mode and the skip mode is a 2:1 skip mode.

11. A method for controlling a switched capacitor converter, comprising: coupling an input of a switched capacitor converter to a battery, and coupling an output of the switched capacitor converter to a system load and a charger; configuring the switched capacitor converter to operate in a 1:2 fixed PWM mode to charge the battery; configuring the switched capacitor converter to operate in a 2:1 fixed PWM mode to discharge the battery; and The switched capacitor converter is configured to operate in a 2:1 skip mode under light load operating conditions, wherein the switched capacitor converter automatically switches between different modes based on a comparison between an output voltage of the switched capacitor converter and a plurality of predetermined voltage thresholds, the automatic switching comprising directly switching between any two of the 1:2 fixed PWM mode, the 2:1 fixed PWM mode, and the 2:1 skip mode.

12. The method of claim 11, further comprising: In response to an increase in load current, the switched capacitor converter is configured to leave the 2:1 skip mode and enter the 2:1 fixed PWM mode by comparing the output voltage of the switched capacitor converter with a 1:2 fixed PWM mode voltage threshold, wherein the 1:2 fixed PWM mode voltage threshold is less than half of the input voltage of the switched capacitor converter.

13. The method of claim 11, further comprising: After the charger starts to supply power to the output terminal of the switched capacitor converter, the switched capacitor converter is configured to leave the 2:1 fixed PWM mode and enter the 1:2 fixed PWM mode by comparing the output voltage of the switched capacitor converter with a 2:1 fixed PWM mode voltage threshold, wherein the 2:1 fixed PWM mode voltage threshold is greater than half of the input voltage of the switched capacitor converter.

14. The method of claim 11, further comprising: After the charger stops supplying power to the output terminal of the switched capacitor converter and the output voltage of the switched capacitor converter is maintained at half of the input voltage of the switched capacitor converter, upon detecting that the current flowing through the switched capacitor converter is equal to a predetermined sink current, the switched capacitor converter is configured to leave the 1:2 fixed PWM mode and enter the 2:1 skip mode.

15. The method of claim 11, further comprising: After the charger starts to supply power to the output terminal of the switched capacitor converter, the switched capacitor converter is configured to leave the 2:1 skip mode and enter the 1:2 fixed PWM mode by comparing the output voltage of the switched capacitor converter with a 2:1 fixed PWM mode voltage threshold, wherein the 2:1 fixed PWM mode voltage threshold is greater than half of the input voltage of the switched capacitor converter.

16. The method of claim 11, further comprising: After the battery has been fully charged and the output voltage of the switched capacitor converter is maintained at half of the input voltage of the switched capacitor converter, upon detecting that the current flowing through the switched capacitor converter is equal to a predetermined sink current, the switched capacitor converter is configured to leave the 1:2 fixed PWM mode and enter the 2:1 skip mode.

17. A controller comprising: a first comparator configured to compare an output voltage of a switched capacitor converter with a first fixed PWM mode threshold voltage, wherein the first fixed PWM mode threshold voltage is greater than half an input voltage of the switched capacitor converter; a second comparator configured to compare the output voltage of the switched capacitor converter to a skip mode threshold voltage; a third comparator configured to compare the output voltage of the switched capacitor converter with a threshold voltage for initiating a skip mode; a fourth comparator configured to compare the output voltage of the switched capacitor converter with a second fixed PWM mode threshold voltage, wherein the second fixed PWM mode threshold voltage is less than half of the input voltage of the switched capacitor converter; and A fifth comparator is configured to compare the current flowing through the switched capacitor converter with a predetermined sink current to determine whether the switched capacitor converter enters the skip mode under a light load operating condition.

18. The controller of claim 17, further comprising: a plurality of gate drivers configured to generate a plurality of gate drive signals for driving the switched capacitor converter, wherein output results of the first comparator, the second comparator, the third comparator, the fourth comparator and the fifth comparator are used to determine an operation mode of the switched capacitor converter.

19. The controller of claim 17, wherein: The switched capacitor converter comprises: A first switch, a second switch, a third switch and a fourth switch, wherein the first switch, the second switch, the third switch and the fourth switch are connected in series between an input terminal of the switched capacitor converter and ground; a first 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; a fifth switch, a sixth switch, a seventh switch and an eighth switch, wherein the fifth switch, the sixth switch, the seventh switch and the eighth switch are connected in series between the input terminal of the switched capacitor converter and ground; and a second flying capacitor, wherein the second flying capacitor is connected between a common node of the fifth switch and the sixth switch and a common node of the seventh switch and the eighth switch, and wherein the common node of the second switch and the third switch is connected to a common node of the sixth switch and the seventh switch and is also connected to an output terminal of the switched capacitor converter.

20. The controller of claim 17, wherein: After the output voltage of the switched capacitor converter exceeds the first fixed PWM mode threshold voltage, the switched capacitor converter is configured to operate in a 1:2 fixed PWM mode; After the output voltage of the switched capacitor converter drops below the second fixed PWM mode threshold voltage, the switched capacitor converter is configured to operate in a 2:1 fixed PWM mode; and After finding the light load operating condition, the switched capacitor converter is configured to operate in a 2:1 skip mode.

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