Two-stage battery charger with midpoint voltage regulation

Abstract

The invention relates to a two-stage battery charger with midpoint voltage regulation. Devices, apparatuses, and methods for operating a battery charger are described. The semiconductor device may include a controller that may monitor at least one battery parameter of a battery connected to a secondary of the two-stage battery charger. The controller may determine a threshold voltage based on at least one battery parameter. The controller may adjust the midpoint voltage at a threshold voltage. The neutral-point voltage may be provided by a primary of the two-stage battery charger to a secondary of the two-stage battery charger. The controller may operate the secondary in a non-switching mode to provide a midpoint voltage regulated at the threshold voltage directly to the battery.

Description

Technical Field

[0001] The present disclosure generally relates to semiconductor devices. More specifically, the present disclosure relates to the operation of a two-stage battery charger, and switching losses can be reduced by adjusting the midpoint voltage between the two stages in the two-stage battery charger. Background Art

[0002] Devices including a battery can receive power for charging the battery and / or for powering a load in the device or a load connected to the device. The power can be provided by a power adapter or various types of voltage sources (such as a Universal Serial Bus (USB) adapter). In some aspects, the received power can provide an input voltage that can be higher or lower than the voltage of the battery and / or the voltage of the load. The internal power converter of the device can step down or step up the input voltage in order to provide power with an appropriate voltage level to the battery and the load. A controller (such as a microcontroller) can control the operation of these internal power converters based on various quantitative measurements of the battery, load, and other components of the device. The quantitative measurements can be used by the controller to execute control loops that can adjust the parameters and / or settings of the internal power converter to optimize performance (such as efficiency and power consumption, etc.), and prevent dangerous situations related to the battery charger. Summary of the Invention

[0003] In one embodiment, a semiconductor device for operating a battery charger is generally described. The semiconductor device can include a controller configured to monitor at least one battery parameter of a battery connected to the secondary of a two-stage battery charger. The controller can also be configured to determine a threshold voltage based on the at least one battery parameter. The controller can also be configured to adjust the midpoint voltage at the threshold voltage. The midpoint voltage can be provided by the primary of the two-stage battery charger to the secondary of the two-stage battery charger. The controller can also be configured to operate the secondary in a non-switching mode to directly provide the midpoint voltage adjusted at the threshold voltage to the battery.

[0004] In one embodiment, a system for operating a battery charger is generally described. The system can include a battery module. The system can also include a primary configured to convert an input voltage into a midpoint voltage. The system can also include a secondary configured to convert the midpoint voltage into a system voltage for charging the battery module. The system can also include a controller. The controller can be configured to monitor at least one battery parameter of the battery. The controller can also be configured to determine a threshold voltage based on the at least one battery parameter. The controller can also be configured to adjust the midpoint voltage at the threshold voltage. The controller can also be configured to operate the secondary in a non-switching mode to directly provide the midpoint voltage adjusted at the threshold voltage to the battery.

[0005] In one embodiment, a method for operating a battery charger is generally described. The method may include: monitoring at least one battery parameter of a battery that is connected to the secondary of a two-stage battery charger. The method may also include comparing an input voltage provided to the primary of the two-stage battery charger with the battery voltage of the battery, wherein the input voltage is among the at least one battery parameter. The method may further include: operating the secondary of the two-stage battery charger in a switching mode when the input voltage is less than the battery voltage. The method may also include: determining a threshold voltage based on at least one battery parameter when the input voltage is greater than the battery voltage. The method may further include: adjusting a midpoint voltage at the threshold voltage. The midpoint voltage may be provided by the primary of the two-stage battery charger to the secondary of the two-stage battery charger. The method may also include: operating the secondary in a non-switching mode to directly provide the midpoint voltage adjusted at the threshold voltage to the battery.

[0006] Additional features and the structure and operation of various embodiments are described in detail below with reference to the drawings. In the drawings, like reference numerals indicate elements having the same or similar functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is an exemplary schematic diagram of a system in which a two-stage battery charger with midpoint voltage regulation can be implemented in one embodiment.

[0008] Figure 2 is a schematic diagram showing an implementation of the Figure 1 system in one embodiment.

[0009] Figure 3 is a schematic diagram showing an example of waveforms generated by an implementation of Figure 2 in one embodiment.

[0010] Figure 4 is an exemplary schematic diagram of another system in which a two-stage battery charger with midpoint voltage regulation can be implemented in one embodiment.

[0011] Figure 5 is a schematic diagram showing an implementation of the Figure 3 system in one embodiment.

[0012] Figure 6 is a schematic diagram showing an example of waveforms generated by an implementation of Figure 5 in one embodiment.

[0013] Figure 7 is a flowchart illustrating a process for implementing a two-stage battery charger with midpoint voltage regulation in one embodiment.

[0014] Figure 8is a flowchart illustrating another process for implementing a two - stage battery charger with mid - point voltage regulation in one embodiment. Detailed Description

[0015] In the following description, numerous specific details are set forth, such as particular structures, components, materials, dimensions, processing steps, and techniques, in order to provide an understanding of various embodiments of the present application. However, one of ordinary skill in the art will understand that the various embodiments of the present application may be practiced without these specific details. In other instances, well - known structures or processing steps have not been described in detail to avoid obscuring the present application.

[0016] Figure 1 is an exemplary schematic diagram of a system in one embodiment that can implement a two - stage battery charger with mid - point voltage regulation. Figure 1 The illustrated system 100 can be a dual - state battery charging system implemented in a battery charger or a device that includes a battery module 140. The system 100 can include a port 101, a power delivery circuit 110, a first stage 120, and a second stage 130. In an embodiment where the system 100 is implemented in a device that includes a battery module 140, the battery module 140 can be part of the system. The port 101 can be a Universal Serial Bus Type - C (USB - C) port or an adapter that can receive power from a power source internal or external to the system 100. In one embodiment, a load 104 can be connected to the system 100 (e.g., connected to the output of the second stage 130). In another embodiment, the load 104 can be part of the system 100. The device that can include the system 100 can be an electronic device, such as, for example, a desktop computer, a laptop computer, a tablet device, a smartwatch, a cellular phone, a smartphone, a wearable device, an electronic cigarette, etc. The load 104 can be a component in the device that includes the system 100, such as a component that operates at a specific voltage and obtains current from the battery module 140 and / or the port 101. The battery module 140 can be a battery pack that includes at least one battery.

[0017] The Power Delivery (PD) circuit 110 may include a controller 112 that controls various aspects of the power delivery circuit 102, such as determining the source and sink of the charging device, negotiation and authentication, determining the charging direction, operating components (such as switches in the power delivery circuit 102), and so on. In one embodiment, the PD circuit 110 may be an Extended Power Range (EPR) Power Delivery (PD) adapter for a USB-C port, supporting high-voltage power delivery (e.g., Universal Serial Bus Power Delivery (USB-PD) version 3.1). For example, the input voltage Vin received by the PD circuit via port 101 may be up to 48 volts (V), such that the PD circuit 110 can output up to 240 watts (W) of adapter power, with a maximum current limit set to 5 amperes (A). The PD circuit 110 may output power with the input voltage Vin to the first stage 120.

[0018] The first stage 120 may be a first voltage conversion stage that converts the input voltage Vin received at port 101 and provided by the PD circuit 110 into a midpoint voltage Vmid. The first stage 120 may be implemented by a multilevel switched converter (such as a three-level buck converter formed by switching elements M1, M2, M3, M4 and a flying capacitor Cfly). The switching elements M1, M2, M3, M4 may be metal-oxide-semiconductor field-effect transistors (MOSFETs) and may be connected in series. The first stage 120 may include a controller 122. The controller 122 may be a three-level buck controller configured to switch the switching elements M1, M2, M3, M4 and control the voltage of Cfly. For example, since the first stage 120 is implemented as a three-level buck converter, the first stage 120 may alternatively output its output voltage as voltages 0V, Vmid / 2, and Vmid, where Vmid may be less than Vin. The controller 122 may be configured to execute one or more control loops to regulate Vmid at a target voltage level.

[0019] The second stage 130 can be a second voltage conversion stage that converts the midpoint voltage Vmid to the system voltage Vsys. The system voltage Vsys can be used to charge the battery module 140 and / or the load 104. In one embodiment, the second stage 130 can be implemented by a narrow voltage direct charge (NVDC) battery charger (e.g., an NVDC 4-switch buck-boost battery charger). The combination of the first stage 120 and the second stage 130 can allow the Vin provided by the PD circuit 110 to be gradually reduced to a low voltage level for a load that may require a significantly lower operating voltage. In some aspects, the buck-boost converter in the second stage 130 can have a maximum input voltage less than Vin (e.g., about 12V), and thus cannot directly receive Vin. If Vin is 48V, the first stage 120 can first gradually reduce the input voltage of 48V to the Vmid of 12V, and then provide the 12V Vmid to the second stage 130. The buck-boost converter in the second stage 130 can gradually increase or gradually reduce Vmid (e.g., 12V) to generate the desired voltage level of Vsys. The second stage 130 can include a controller 132. The controller 132 can be a dual-level buck-boost controller configured to execute one or more control loops to control the switching elements Q1, Q2, Q3, Q4 such that Vsys can be regulated at the target voltage level.

[0020] For example, the controllers 112, 122, 132 can be microcontrollers. The controllers 112, 122, 132 can be implemented by one or more semiconductor devices. Each of the controllers 112, 122, 132 can include components such as a processor, logic circuits, a digital-to-analog converter (DAC), a comparator, a mixer, a memory device (e.g., a register), and various electronic components. The controllers 112, 122, 132 can also include memory devices (such as registers) configured to store various predefined reference values and thresholds that may be required to execute various types of loops, including voltage control loops and current control loops. In one embodiment, the controllers 112, 122, 132 can be configured to communicate with each other. In one embodiment, the controllers 112, 122, 132 can be part of a single microcontroller. In one embodiment, the controllers 112, 122, 132 can be connected to the controller 108, where the controller 108 can be the microcontroller of the device including the system 100. For example, if the system 100 is part of a smartphone, the controller 108 can include the central processing unit (CPU) of the smartphone, and the controllers 112, 122, 132 can be separate controllers on a separate voltage converter integrated circuit (IC) implementing the PD circuit 110, the first stage 120, and the third stage 130.

[0021] The second stage 130 can operate in various operating modes to generate Vsys. If the battery module 140 is fully charged, the controller 132 can turn off the BFET. When the device including the system 100 is in the on-the-go (OTG) mode, such as when the port 101 is disconnected from any power source, the controller 132 can turn on the BFET to discharge the battery module 140 to provide Vsys. In one embodiment, when the port 101 connects the system 100 to another device or load that can obtain power from the system 100, the controller 132 can turn on the BFET to discharge the battery module 140 to supply power to the device connected to the port 101 in the reverse mode. In the forward charging mode, the controller 132 can turn on the BFET, the controller 122 can switch the switching elements M1, M2, M3, M4 to convert Vin to Vmid, and the controller 132 can switch the switching elements Q1, Q2, Q3, Q4 to convert Vmid to Vsys for charging the battery module 140.

[0022] The second stage 130 may further include a fuel gauge integrated circuit (FGIC) 134. The FGIC 134 may be located between the BFET and the battery module 140. The FGIC 134 may include one or more coulomb counters configured to measure and count various parameters of the battery module 140 and convert the parameters into a signal 136. The signal 136 may be an analog or digital signal representing one or more parameters, including but not limited to the state of charge, battery capacity, remaining battery percentage, battery voltage (e.g., VBAT), battery current or charging current IBAT, battery health, battery temperature, estimated runtime, or other parameters of the battery module 140.

[0023] In some aspects, when Vmid is less than the target voltage of VBAT, the second stage 130 can gradually increase Vmid to generate Vsys that can support VBAT. Similarly, when Vmid is greater than the target voltage of VBAT, the second stage 130 can gradually decrease Vmid to generate Vsys that can support VBAT. Regardless of whether Vmid is greater than or less than the target voltage of VBAT, the second stage 130 switches Q1, Q2, Q3, Q4 to perform boosting or bucking. The controller 132 receives feedback of Vsys, VBAT, battery current or charging current IBAT, and other parameters related to the output from the second stage 130. The controller 132 can perform switching in the second stage 130 to regulate Vsys at the target voltage level of Vsys. In addition, the first stage 120 also switches M1, M2, M3, M4 to gradually reduce Vin to Vmid. The controller 122 receives feedback of Vmid and can perform switching in the first stage 120 to regulate Vmid at the target voltage level of Vmid.

[0024] When the first stage 120 and the second stage 130 actively switch their respective switching elements, the system 100 may experience switching losses, and the switching losses can have a negative impact on the operating efficiency of the system 100. For a more detailed description below, in order to reduce the switching losses, the controller 108 can receive the signal 136 and use the signal 136 to determine the threshold voltage 138. In one embodiment, the threshold voltage 138 can be the target voltage of the first stage 120 for regulating Vmid (e.g., it is desired to regulate Vmid at the threshold voltage 138). In addition to regulating Vmid based on the signal 136, the second stage 130 can also operate in a non-switching operation mode (such as the through mode (PTM)), where the regulated Vmid is directly provided to VBAT and / or Vsys without switching Q1, Q2, Q3, Q4 in the second stage 130, thereby reducing the switching losses. In addition, the controller 108 can be configured to determine the conditions for the second stage 130 to continue operating in the switching mode or in a non-switching mode (such as PTM). By monitoring the parameters of the battery module 140 and using the monitored parameters to regulate Vmid, compared with both the first stage 120 and the second stage 130 operating in the switching mode, the switching in the second stage 130 can be avoided to reduce the switching losses.

[0025] Figure 2 shows an embodiment of Figure 1 the system. In one embodiment, the signal 136 can include at least an analog or digital signal representing the battery voltage VBAT and the charging current IBAT. The charging current IBAT can be the charging current of the battery module 140. In Figure 2 the embodiment shown, the controller 108 can determine the threshold voltage 138 using the following expression:

[0026] Vtar = VBAT + IBAT * (R2 + Rdson(Q1 + Q4 + BFET))

[0027] where Vtar is the threshold voltage 138, R2 is the resistance of the resistor R2 in the second stage 130, and Rdson(Q1 + Q4 + BFET) is the sum of the on-resistances of the switching elements Q1, Q4, BFET (e.g., the drain-source resistance when the switching elements Q1, Q4, BFET are turned on). Note that the above expression for the threshold voltage 138 takes into account the current path of IBAT through the resistor R2 and the switching elements Q1, Q4, BFET. When the second stage 130 operates in a non-switching mode (such as PTM), this current path is the current path of IBET. In PTM, the high-side switching elements Q1, Q4 in the second stage 130 remain on, and the low-side switching elements Q2, Q3 remain off (OFF), as Figure 2As shown. Under PTM, Vmid adjusted under Vtar can be directly provided to the battery module 140 to charge the battery module 140 without switching the buck-boost converter in the second stage 130.

[0028] In one embodiment, in response to a power supply being connected to port 101 to provide Vin, the controller 108 can also measure the input voltage Vin across the resistor R1 between the PD circuit 110 and the first stage 120. The controller 108 can compare VBAT (indicated by signal 136) with the input voltage Vi n and. If Vi n is greater than VBAT, the controller 108 can determine that the second stage 130 can operate in a non-switching mode. To operate the second stage 130 in a non-switching mode (such as PTM) Figure 2 the controller 108 in the second stage 130 can be notified to turn on the switching elements Q1, Q4 and turn off the switching elements Q2, Q3 to operate the second stage 130 in a non-switching mode (such as PTM). Similarly, in response to determining that Figure 2 the second stage 130 can operate in a non-switching mode, the controller 108 can disable the first stage 120. In response to disabling the first stage 120, the controller 108 can determine the threshold voltage 138, and send the threshold voltage 138 to the controller 122 in the first stage 120, and also enable the first stage 120. The controller 122 can receive the threshold voltage 138, and in response to receiving the threshold voltage 138 and being enabled by the controller 108, generate a control signal (such as a pulse width modulation (PWM) signal) to drive M1, M2, M3, M4 in a specific switching sequence and duty cycle, thereby adjusting Vmid at the threshold voltage 138.

[0029] As Vmid changes, the charging current IBAT and the battery voltage VBAT can also change, and the FGIC 134 can continue to monitor IBAT and VBAT. The controller 108 can continue to receive signal 136, and monitor VBAT against Vin to determine Figure 2 whether the second stage 130 should continue to operate in a non-switching mode or resume to a switching mode. For example, when Vin is less than VBAT, the controller 108 can Figure 2 restore the second stage 130 to a switching mode (such as a buck-boost converter), and notify the controller 122 in the first stage 120 to adjust Vmid regardless of the threshold voltage 138.

[0030] In one embodiment, when the battery module 140 is fully charged or when VBAT reaches the minimum VBAT value, if the battery module 140 is charged too fast (e.g., IBAT is too high), it may damage the battery module. To prevent damage to the battery module 140, in addition to determining whether Vin is greater than VBAT, the controller 108 may also determine whether the battery module 140 is fully charged (whether VBAT is at the minimum value) to determine Figure 2 whether the second stage 130 in Figure 2 should operate in the trickle charge mode before starting the non-switching mode. If Vin is greater than VBAT and the signal 136 indicates that the battery module 140 is fully charged, the controller 108 may command the controller 132 to control Figure 2 the second stage 130 in

[0031] the trickle charge mode to slowly charge the battery module 140. When VBAT reaches a voltage level that is considered a safe voltage level for charging the battery module 140, and if Vin remains greater than VBAT, the controller 108 may disable the first stage 120, command Figure 2 the second stage 130 in

[0032] Figure 3 to enter the non-switching mode, and determine the threshold voltage 138 for the Vmid regulation performed by the first stage 120. Figure 2 Figure 3 Figure 3In the example shown, when Vin is greater than VBAT, the second stage 130 can operate in a non-switching mode (such as a through mode). When the second stage 130 operates in the PTM, the first stage 120 continues to operate in the switching mode, as shown by the states of the switching elements M1, M2, M3, M4 that change between state 0 (e.g., off) and state 1 (e.g., on). Similarly, when the second stage 130 operates in the PTM, the switching elements Q1, Q4 in the second stage 130 remain on, and the switching elements Q2, Q3 in the second stage 130 remain off. When the second stage 130 operates in the PTM, the switching losses generated by the second stage 130 can be zero. When Vin is less than VBAT, both the first stage 120 and the second stage 130 can operate in the switching mode.

[0033] Figure 4 FIG. is a schematic diagram of another example of a system 300 that can implement a two-stage battery charger with midpoint voltage regulation in one embodiment. In Figure 4 In the embodiment shown, the second stage 130 can be implemented by a 4-switch hybrid power buck-boost (HPBB) bypass buck-boost converter, which consists of switching elements Q1, Q2, Q3, Q4 and a set of devices S1, S2 that can form the switching element Qbp, where S1, S2 can be MOSFETs. The controller 132 can turn on and off the switching elements S1, S2, and can control the switching element Qn to connect and disconnect the switching elements S1, S2 from Vsys. The second stage 130 can operate the HPBB bypass buck-boost converter in various operating modes to generate Vsys.

[0034] In the bypass mode, the power of Vmid can not only be used to support Vsys, but also be used to charge the battery module 140. For example, when the power of Vmid is greater than the power of Vsys, the power of Vmid can support Vsys via S1 and S2, and the remaining power from Vmid can be used to charge the battery module 140 by switching Q1, Q2, Q3, and Q4. When the battery module 140 is not being charged, the switching of Q1, Q2, Q3, and Q4 can be disabled, so the second stage 130 can operate in a non-switching mode. In the NVDC mode, Vmid can support Vsys by switching Q1, Q2, Q3, and Q4 while keeping S1 and S2 off to charge the battery module 140. In the NVDC turbo mode, both Vmid and the battery module 140 can support Vsys. In the reverse turbo boost (RTB) mode, Vmid may not be sufficient to support Vsys, and the battery module 140 can supplement Vmid by keeping the BFET on to allow power to be provided from the battery module 140 to Vsys. In the pure battery mode (which can also be the OTG mode), port 101 is disconnected from any power source, and the controller 132 can turn on the BFET to discharge the battery module 140 to provide Vsys. If the battery module 140 is fully charged, the controller 132 can turn off the BFET.

[0035] Similar to Figure 1 the system 100 shown, to reduce switching losses, the controller 108 can be configured to determine the conditions for the second stage 130 to continue operating in the switching mode or in the non-switching mode, where the switching elements Q1, Q2, Q3, and Q4 can remain off while the switching elements S1 and S2 can remain on. By monitoring the parameters of the battery module 140 and using the monitored parameters to adjust Vmid, compared with the first stage 120 and the second stage 130 both operating in the switching mode, the switching in the second stage 130 can be avoided to reduce switching losses.

[0036] Figure 5 is a schematic diagram showing an implementation of Figure 3 the system in one embodiment. In one embodiment, the signal 136 can include at least analog or digital signals representing the battery voltage VBAT and the charging current IBAT. The charging current IBAT can be the charging current of the battery module 140. In Figure 5 the embodiment shown, the controller 108 can determine the threshold voltage 138 using the following expression:

[0037] Vtar = VBAT + IBAT * (R2 + Rdson(Qbp + Qn + BFET))

[0038] Where Vtar is the threshold voltage 138, R2 is the resistance of resistor R2 in the second stage 130, and Rdson(Qbp+Qn+BFET) is the sum of the on-resistances of the switching elements Qbp, Qn, and BFET (e.g., the drain-source resistance when the switching elements Qbp, Qn, and BFET are turned on). Note that the above expression for the threshold voltage 138 takes into account the current path of IBAT through resistor R2 and the switching elements Qbp, Qn, and BFET. When the second stage 130 operates in a non-switching mode (such as a bypass mode where S1 and S2 are turned on and Q1, Q2, Q3, and Q4 are turned off (OFF)), this current path is the current path of IBET. In this non-switching mode, Vmid regulated at Vtar can be directly supplied to the battery module 140 to charge the battery module 140 without performing switching in the second stage 130.

[0039] In one embodiment, in response to the power supply being connected to port 101 to provide Vin, the controller 108 can also measure the input voltage Vin across resistor R1 between the PD circuit 110 and the first stage 120. The controller 108 can compare VBAT (indicated by signal 136) with the input voltage Vin. If Vin is greater than VBAT, the controller 108 can determine that the second stage 130 can operate in a non-switching mode. To operate the second stage 130 in the non-switching mode Figure 5 of, the controller 108 can notify the controller 132 in the second stage 130 to turn on the switching elements S1 and S4 and turn off the switching elements Q1, Q2, Q3, and Q4 to operate the second stage 130 in the non-switching mode. Similarly, in response to determining Figure 5 that the second stage 130 can operate in a non-switching mode, the controller 108 can disable the first stage 120. In response to disabling the first stage 120, the controller 108 can determine the threshold voltage 138 and send the threshold voltage 138 to the controller 122 in the first stage 120, and also enable the first stage 120. The controller 122 can receive the threshold voltage 138 and, in response to receiving the threshold voltage 138 and being enabled by the controller 108, generate a control signal (e.g., a pulse width modulation (PWM) signal) to drive M1, M2, M3, and M4 in a specific switching sequence and duty cycle to regulate Vmid at the threshold voltage 138.

[0040] As Vmid changes, the charging current IBAT and the battery voltage VBAT can also change, and the FGIC 134 can continue to monitor IBAT and VBAT. The controller 108 can continue to receive signal 136 and monitor VBAT against Vin to determine Figure 5whether the second stage 130 in Figure 5 should continue to operate in the non-switching mode or revert to the switching mode. For example, when Vin is less than VBAT, the controller 108 may revert the second stage 130 in

[0041] to the switching mode (e.g., as a buck-boost converter) and notify the controller 122 in the first stage 120 to adjust Vmid, regardless of the threshold voltage 138. Figure 5 In one embodiment, when the battery module 140 is fully charged or when VBAT reaches the minimum VBAT value, the battery module 140 may be damaged if it is charged too fast (e.g., IBAT is too high). To prevent damage to the battery module 140, in addition to determining whether Vin is greater than VBAT, the controller 108 may also determine whether the battery module 140 is fully charged (whether VBAT is at the minimum value) in order to determine Figure 5 whether the second stage 130 in Figure 5 should operate in the trickle charging mode before starting the non-switching mode. If Vin is greater than VBAT and the signal 136 indicates that the battery module 140 is fully charged, the controller 108 may command the controller 132 to control

[0042] the second stage 130 in Figure 5 to operate in the trickle charging mode to slowly charge the battery module 140. When VBAT reaches a voltage level that is considered a safe voltage level for charging the battery module 140 and if Vin remains greater than VBAT, the controller 108 may disable the first stage 120, command Figure 5 the second stage 130 in

[0042] to enter the non-switching mode, and determine the threshold voltage 138 for the Vmid adjustment performed by the first stage 120.

[0042] In one embodiment, when Figure 5 the second stage 130 operates in the non-switching mode (where Q1, Q2, Q3, Q4 are turned off and S1, S2 are turned on), the controller 108 may execute a charging current control loop by monitoring the charging current IBAT that may be indicated by the signal 136. For example, if IBAT is greater than a predefined charging current threshold, the controller 108 may maintain the threshold voltage 138 such that the first stage 120 can adjust the midpoint voltage Vmid at the current voltage level of Vtar. If IBAT is less than the predefined charging current threshold, the controller 108 may increase the threshold voltage 138 such that the first stage 120 can adjust the midpoint voltage Vmid at a higher voltage level to increase the charging current IBAT for charging the battery module 140. The charging current control loop may allow charging the battery module 140 with a sufficient charging current.

[0043] Figure 6 is an example schematic diagram showing waveforms generated by the implementation of an embodiment in Figure 5 InFigure 6 In the illustrated example, when Vin is greater than VBAT, the second stage 130 can operate in a non-switching mode (such as a bypass mode). When the second stage 130 operates in the bypass mode, the first stage 120 continues to operate in the switching mode, as shown by the states of the switching elements M1, M2, M3, M4 that change between state 0 (e.g., off) and state 1 (e.g., on). Similarly, when the second stage 130 operates in the bypass mode, the switching elements Q1, Q2, Q3, Q4 in the second stage 130 remain off (S1, S2 remain on). When the second stage 130 operates in the bypass mode, the switching losses generated by the second stage 130 can be zero. When Vin is less than VBAT, both the first stage 120 and the second stage 130 can operate in the switching mode.

[0044] Figure 7 is a flowchart illustrating a process for implementing a two-stage battery charger with midpoint voltage regulation in one embodiment. Figure 7 The description of which can refer to Figures 1 to 6 the components shown. Process 700 can include one or more operations, actions, or functions, as illustrated by one or more of the blocks in blocks 702, 704, 706, 708, 710, and / or 712. Although illustrated as discrete blocks, depending on the desired implementation, the various blocks can be divided into additional blocks, combined into fewer blocks, eliminated, executed in a different order, or executed in parallel.

[0045] Process 700 can be executed by one or more controllers, such as controller 108 or Figures 1 to 6 a combination of controllers 108, 112, 122, 132 shown in at least one of

[0046] Process 700 can continue from block 702 to block 704. At block 704, the controller can compare the input voltage Vin provided to the primary of the two-stage battery charger with the battery voltage VBAT of the battery. The input voltage Vin can be among the at least one battery parameter monitored in block 702.

[0047] When the input voltage Vin is less than the battery voltage VBAT, process 700 can continue from block 704 to block 706. At block 706, the controller can operate the secondary of the two-stage battery charger in the switching mode.

[0048] When the input voltage Vin is greater than the battery voltage VBAT, process 700 can proceed from block 704 to block 708. At block 708, the controller can determine a threshold voltage based on at least one battery parameter. In one embodiment, the controller can determine the threshold voltage based at least on the following: the battery voltage of the battery, the battery current of the battery, the resistance of a sense resistor connected to the battery, and the on-resistance of at least one switching element turned on in a non-switching mode.

[0049] Process 700 can proceed from block 708 to block 710. At block 710, the controller can regulate a midpoint voltage at the threshold voltage. The midpoint voltage can be provided from the primary of a two-stage battery charger to the secondary of the two-stage battery charger.

[0050] Process 700 can proceed from block 710 to block 712. At block 712, the controller can operate the secondary in a non-switching mode to directly provide the midpoint voltage regulated at the threshold voltage to the battery.

[0051] In one embodiment, the primary can include a three-level buck converter, and the secondary can include a two-level buck-boost converter. The non-switching mode can be a direct-through mode, where the high-side switching element in the secondary remains on, and the low-side switching element in the secondary remains off.

[0052] In one embodiment, the primary can include a three-level buck converter, and the secondary can include a hybrid power buck-boost (HPBB) bypass buck-boost converter. The non-switching mode can be a bypass mode, where the buck-boost converter in the secondary is turned off, and a set of bypass switching elements in the secondary remains on.

[0053] In one embodiment, the controller can determine that the battery voltage of the battery reaches a minimum value. The controller can operate the secondary of the two-stage battery charger in a trickle charge mode. The controller can determine that the battery voltage reaches a safe voltage level. The controller can determine the threshold voltage and operate the secondary of the two-stage battery charger in a non-switching mode.

[0054] Figure 8 is a flowchart illustrating another process for implementing a two-stage battery charger with midpoint voltage regulation in one embodiment. Figure 8 The description of can refer to Figures 1 to 6 the components shown in. Process 800 can include one or more operations, actions, or functions, as shown by one or more of the blocks in blocks 802, 804, 806, 808, 810, 812, 814, 816, 818, and / or 820. Although illustrated as discrete blocks, various blocks can be divided into additional blocks, combined into fewer blocks, eliminated, executed in a different order, or executed in parallel according to the desired implementation.

[0055] Process 800 can be executed by one or more controllers, such as controller 108 or a combination of controllers 108, 112, 122, 132 as shown by at least one of them. Process 800 can start at block 802. At block 802, the controller can monitor the battery voltage VBAT of the battery connected to the secondary of the two-stage battery charger. Figures 1 to 6 Process 800 can continue from block 802 to block 804. At block 804, the controller can compare the input voltage Vin provided to the primary of the two-stage battery charger with the battery voltage VBAT of the battery.

[0056] When the input voltage Vin is less than the battery voltage VBAT, process 800 can continue from block 804 to block 806. At block 806, the controller can operate the secondary of the two-stage battery charger in a switching mode.

[0057] When the input voltage Vin is greater than the battery voltage VBAT, process 800 can continue from block 804 to block 808. At block 808, the controller can determine a threshold voltage based on at least one battery parameter. In one embodiment, the controller can determine the threshold voltage based at least on the following: the battery voltage of the battery, the battery current of the battery, the resistance of the sense resistor connected to the battery, and the on-resistance of at least one switching element turned on in a non-switching mode.

[0058] Process 800 can continue from block 808 to block 810. At block 810, the controller can adjust the midpoint voltage at the threshold voltage. The midpoint voltage can be provided by the primary of the two-stage battery charger to the secondary of the two-stage battery charger.

[0059] Process 800 can continue from block 810 to block 812. At block 812, the controller can operate the secondary in a non-switching mode to directly provide the midpoint voltage adjusted at the threshold voltage to the battery.

[0060] Process 800 can continue from block 812 to block 814. At block 814, in the non-switching mode of block 812, the controller can monitor the battery charging current IBAT of the battery connected to the secondary of the two-stage battery charger.

[0061] Process 800 can continue from block 814 to block 816. At block 816, the controller can compare the charging current IBAT with a predefined charging current threshold IBAT_SET.

[0062] When the charging current IBAT is equal to or greater than IBAT_SET, process 800 can return to block 810 to continue adjusting the midpoint voltage at the threshold voltage.

[0063] When the charging current IBAT is equal to or greater than IBAT_SET, process 800 can return to block 810 to continue adjusting the midpoint voltage at the threshold voltage.

[0064] When the charging current IBAT is less than IBAT_SET, process 800 can proceed from block 816 to block 818. At block 818, the controller can increase the threshold voltage.

[0065] Process 800 can proceed from block 808 to block 820. At block 820, the controller can adjust the midpoint voltage at the increased threshold voltage. Process 800 can proceed to block 812, where the controller operates the second stage in a non-switching mode using the adjusted midpoint voltage.

[0066] The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagram can represent a module, segment, or portion of instructions, including one or more executable instructions for implementing a particular logical function. In certain alternative implementations, the functions noted in the blocks can occur in a different order than noted in the figures. For example, two blocks shown in succession can in fact be executed substantially concurrently, or the blocks can sometimes be executed in the reverse order, depending on the functionality involved. It will also be noted that each block of the block diagrams and / or flowchart illustrations, and combinations of blocks in the block diagrams and / or flowchart illustrations, can be implemented by dedicated hardware-based systems that perform the specified functions or acts or carry out combinations of dedicated hardware and computer instructions.

[0067] The purpose of the terms used herein is merely to describe particular embodiments and is not intended to limit the present invention. As used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. It will also be understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0068] All methods or steps and corresponding structures, materials, acts, and equivalents of functional elements, if any, in the following claims are intended to include any structure, material, or act for performing a function in combination with other claimed elements as specifically claimed. The disclosed embodiments of the invention have been presented for purposes of illustration and description, but are not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The selection and description of the embodiments were chosen to best explain the principles of the invention and its practical application, and to enable others of ordinary skill in the art to understand the invention in various embodiments with various modifications as are suited to the particular use contemplated.

Claims

1. A semiconductor device, comprising: A controller configured to: Monitor at least one battery parameter of a battery, the battery being connected to the secondary of a two - level battery charger; Determine a threshold voltage based on the at least one battery parameter; Adjust a mid - point voltage at the threshold voltage, wherein the mid - point voltage is provided by the primary of the two - level battery charger to the secondary of the two - level battery charger; And Operate the secondary in a non - switching mode to directly provide the mid - point voltage adjusted at the threshold voltage to the battery.

2. The semiconductor device according to claim 1, wherein: The primary includes a three - level buck converter; and The secondary includes a two - level buck - boost converter, wherein the non - switching mode is a direct - through mode, in which the high - side switching element in the secondary remains on, and the low - side switching element in the secondary remains off.

3. The semiconductor device according to claim 1, wherein: The primary includes a three - level buck converter; and The secondary includes a hybrid power buck - boost (HPBB) bypass buck - boost converter, wherein the non - switching mode is a bypass mode, in which the buck - boost converter in the secondary is turned off, and a set of bypass switching elements in the secondary remains on.

4. The semiconductor device according to claim 1, wherein the at least one battery parameter includes the battery voltage of the battery and the charging current of the battery.

5. The semiconductor device according to claim 1, wherein the controller is configured to determine the threshold voltage based at least on: the battery voltage of the battery, the battery current of the battery, the resistance of a sense resistor connected to the battery, and the on - resistance of at least one switching element turned on in the non - switching mode.

6. The semiconductor device according to claim 1, wherein the controller is configured to: Compare the input voltage provided to the primary with the battery voltage of the battery; When the input voltage is greater than the battery voltage: Determine the threshold voltage; And Operate the secondary of the two - level battery charger in the non - switching mode; And When the input voltage is less than the battery voltage, operate the secondary of the two - level battery charger in a switching mode.

7. The semiconductor device according to claim 1, wherein the controller is configured to: Determine that the battery voltage of the battery reaches a minimum value; Operate the secondary of the two - level battery charger in a trickle - charge mode; Determine that the battery voltage reaches a safe voltage level; And Determine the threshold voltage; And Operate the secondary of the two - level battery charger in the non - switching mode.

8. A system, comprising: A battery module; A primary configured to convert an input voltage into a mid - point voltage; A secondary configured to convert the mid - point voltage into a system voltage for charging the battery module; A controller configured to: Monitor at least one battery parameter of the battery; Determine a threshold voltage based on the at least one battery parameter; Adjust the mid - point voltage at the threshold voltage; And Operate the secondary in a non-switching mode to directly supply the midpoint voltage regulated at the threshold voltage to the battery.

9. The system according to claim 8, wherein: The primary includes a three-level buck converter; and The secondary includes a two-level buck-boost converter, wherein the non-switching mode is a direct-through mode, in which the high-side switching element in the secondary remains on, and the low-side switching element in the secondary remains off.

10. The system according to claim 8, wherein: The primary includes a three-level buck converter; and The secondary includes a hybrid power buck-boost HPBB bypass buck-boost converter, wherein the non-switching mode is a bypass mode, in which the buck-boost converter in the secondary is turned off, and a set of bypass switching elements in the secondary remains on.

11. The system according to claim 8, wherein the at least one battery parameter includes the battery voltage of the battery and the charging current of the battery.

12. The system according to claim 8, wherein the controller is configured to determine the threshold voltage based at least on: the battery voltage of the battery, the battery current of the battery, the resistance of a sense resistor connected to the battery, and the on-resistance of at least one switching element turned on in the non-switching mode.

13. The system according to claim 8, wherein the controller is configured to: Compare the input voltage supplied to the primary with the battery voltage of the battery; When the input voltage is greater than the battery voltage: Determine the threshold voltage; And Operate the secondary in the non-switching mode; And When the input voltage is less than the battery voltage, operate the secondary in a switching mode.

14. The system according to claim 8, wherein the controller is configured to: Determine that the battery voltage of the battery reaches a minimum value; Operate the secondary of the two-stage battery charger in a trickle charging mode; Determine that the battery voltage reaches a safe voltage level; Determine the threshold voltage; And Operate the secondary of the two-stage battery charger in the non-switching mode.

15. A method for operating a battery charger, the method comprising: Monitoring at least one battery parameter of a battery, the battery being connected to the secondary of a two-stage battery charger; Comparing the input voltage supplied to the primary of the two-stage battery charger with the battery voltage of the battery, wherein the input voltage is among the at least one battery parameter; When the input voltage is less than the battery voltage, operating the secondary of the two-stage battery charger in a switching mode; When the input voltage is greater than the battery voltage: Determining a threshold voltage based on the at least one battery parameter; Regulating a midpoint voltage at the threshold voltage, wherein the midpoint voltage is supplied from the primary of the two-stage battery charger to the secondary of the two-stage battery charger; And Operating the secondary in a non-switching mode to directly supply the midpoint voltage regulated at the threshold voltage to the battery.

16. The method according to claim 15, wherein: the primary includes a three-level buck converter; and the secondary includes a two-level buck-boost converter, wherein the non-switching mode is a direct-through mode, in which the high-side switching element in the secondary remains on, and the low-side switching element in the secondary remains off.

17. The method according to claim 15, wherein: the primary includes a three-level buck converter; and the secondary includes a hybrid power buck-boost HPBB bypass buck-boost converter, wherein the non-switching mode is a bypass mode, in which the buck-boost converter in the secondary is turned off, and a set of bypass switching elements in the secondary remains on.

18. The method according to claim 15, wherein the at least one battery parameter includes the battery voltage and charging current of the battery.

19. The method according to claim 15 further comprises: Determine the threshold voltage based at least on the following: the battery voltage of the battery, the battery current of the battery, the resistance of a sense resistor connected to the battery, and the on-resistance of at least one switching element turned on in the non-switching mode.

20. The method according to claim 15, further comprising: determining that the battery voltage of the battery reaches a minimum value; operating the secondary of the two-stage battery charger in a trickle charging mode; determining that the battery voltage reaches a safe voltage level; and determining the threshold voltage; and operating the secondary of the two-stage battery charger in the non-switching mode.

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