System and method for balancing flying capacitors in high power multi-level buck or boost converters for renewable and solar maximum power point tracking (MPPT) inverter applications

Abstract

The present disclosure relates to systems and methods for balancing flying capacitors in high power multi-level buck or boost converters for renewable and solar maximum power point tracking (MPPT) inverter applications. An exemplary method includes initializing at least a multi-level converter circuit arrangement and an isolated secondary converter circuit arrangement, where the multi-level converter circuit arrangement includes at least a flying capacitor, and wherein the isolated secondary converter circuitry is configured to charge the flying capacitor according to a default operating state in response to initialization; determining that the voltage across the flying capacitor satisfies a threshold; and switching the isolated secondary converter circuitry from a default operating state to an inactive state based at least in part on the voltage satisfying a threshold.

Description

Technical Field

[0001] The exemplary embodiments of this disclosure generally relate to systems, apparatus, and methods for balancing flying capacitors in high-power multilevel buck or boost converters for renewable and solar maximum power point tracking (MPPT) inverter applications. Background Technology

[0002] Some renewable energy and high-voltage electric vehicle (EV) applications utilize relatively high operating voltages, such as approximately 800 volts (V) and higher. Multilevel converters can be used in conjunction with low-voltage power devices to support these operating voltages. However, some multilevel converters are associated with hardware and software challenges. For example, some multilevel converters (such as 3-level buck or boost converters) rely on flying capacitors to provide an intermediate operating voltage that stresses the device to a level less than the source voltage, which can be either the input voltage to the multilevel converter or the output voltage from the multilevel converter. Therefore, the voltage across the flying capacitor is constrained to half the source voltage. In some cases, if the voltage across the flying capacitor deviates from half the source voltage, the multilevel converter may be damaged.

[0003] There is a need for new systems and methods for balancing flying capacitors in high-power multilevel buck or boost converters. The inventors have identified numerous areas of improvement in the prior art and processes, which are the subject of the embodiments described herein. Through applied effort, ingenuity, and innovation, many of these deficiencies, challenges, and problems have been addressed by developing solutions included in the embodiments of this disclosure, some examples of which are detailed herein. Summary of the Invention

[0004] The various embodiments described herein relate to systems, apparatuses, and methods for balancing flying capacitors in high-power multilevel buck or boost converters for renewable and solar MPPT inverter applications.

[0005] According to some embodiments of this disclosure, an example system is provided. The example system includes: a multilevel converter circuit arrangement configured to convert a first voltage provided at a first node into a second voltage provided at a second node, wherein the multilevel converter circuit arrangement includes at least a flying capacitor and a plurality of switches coupled to the flying capacitor; and an isolated secondary converter circuit arrangement configured to charge the flying capacitor to a target voltage according to a default operating state, wherein the isolated secondary converter circuit arrangement is configured to switch from the default operating state to an inactive state in response to at least a first event.

[0006] In some embodiments, the system further includes a control circuit means configured to output a first control signal to an isolated secondary converter circuit means in response to detecting a first event, wherein the isolated secondary converter circuit means is configured to operate according to an inactive state in response to receiving the first control signal.

[0007] In some embodiments, the control circuitry is configured to prevent the output of a first control signal to an isolated secondary converter circuitry in response to the detection of a second event, and wherein the isolated secondary converter circuitry is configured to operate according to a default operating state in the absence of the first control signal.

[0008] In some embodiments, the control circuitry is configured to prevent the output of a first control signal for a first duration, the first duration being at least partially based on a second duration during which an isolated secondary converter circuitry charges a flyback capacitor to a target voltage.

[0009] In some embodiments, the first event includes a voltage across the flying capacitor satisfying a threshold associated with the flying capacitor, and the second event includes the voltage not satisfying the threshold.

[0010] In some embodiments, the threshold is based at least in part on the target voltage.

[0011] In some embodiments, the isolated secondary converter circuitry is configured to operate in an open-loop manner.

[0012] In some embodiments, the isolated secondary converter circuitry is configured to charge the flying capacitor by converting a reference voltage provided at a third node into a target voltage, and wherein the reference voltage includes a first voltage or a second voltage based at least in part on the operating mode of the multilevel converter circuitry.

[0013] In some embodiments, the target voltage includes half of the reference voltage.

[0014] In some embodiments, the first voltage is at least partially based on the multilevel converter circuit device operating according to a first operating mode being higher than the second voltage, and wherein the reference voltage includes a first voltage at least partially based on the first voltage being higher than the second voltage.

[0015] In some embodiments, the first operating mode includes a buck mode.

[0016] In some embodiments, the second voltage is at least partially based on the multilevel converter circuit device operating according to a second operating mode being higher than the first voltage, and wherein the reference voltage includes the second voltage at least partially based on the second voltage being higher than the first voltage.

[0017] In some embodiments, the second operating mode includes a boost mode.

[0018] In some embodiments, the plurality of switches includes at least four switches.

[0019] According to some embodiments of this disclosure, an example apparatus is provided. The example apparatus includes: at least one processor; and at least one memory storing computer program code that, when executed by the at least one processor, causes the apparatus to at least: initialize at least a multilevel converter circuit arrangement and an isolated secondary converter circuit arrangement, wherein the multilevel converter circuit arrangement includes at least a flying capacitor, and wherein the isolated secondary converter circuit arrangement is configured to charge the flying capacitor according to a default operating state in response to initialization; determine that a voltage across the flying capacitor satisfies a threshold; and, at least in part based on the voltage satisfying the threshold, switch the isolated secondary converter circuit arrangement from the default operating state to an inactive state.

[0020] In some embodiments, to switch an isolated secondary converter circuit device from a default operating state to an inactive state, the computer program code, when executed by the at least one processor, causes the device to at least: cause a control circuit device to output a first control signal to the isolated secondary converter circuit device, wherein the isolated secondary converter circuit device is configured to operate according to the inactive state in response to receiving the first control signal.

[0021] In some embodiments, when the computer program code is executed by the at least one processor, the device at least: determines that a second voltage across the terminals of the flying capacitor does not meet a threshold; and at least in part based on the second voltage not meeting the threshold, switches the isolated secondary converter circuit device from an inactive state to a default operating state.

[0022] In some embodiments, to switch an isolated secondary converter circuit device from an inactive state to a default operating state, the computer program code, when executed by the at least one processor, causes the device to at least: prevent a control circuit device from outputting a first control signal to the isolated secondary converter circuit device, wherein the isolated secondary converter circuit device is configured to operate according to the default operating state in the absence of the first control signal.

[0023] According to some embodiments of this disclosure, an example method is provided. This example method includes: initializing at least a multilevel converter circuit device and an isolated secondary converter circuit device, wherein the multilevel converter circuit device includes at least a flying capacitor, and wherein the isolated secondary converter circuit device is configured to charge the flying capacitor according to a default operating state in response to initialization; determining that a voltage across the flying capacitor satisfies a threshold; and switching the isolated secondary converter circuit device from the default operating state to an inactive state, at least in part based on the voltage satisfying the threshold.

[0024] In some embodiments, switching an isolated secondary converter circuit device from a default operating state to an inactive state includes: causing a control circuit device to output a first control signal to the isolated secondary converter circuit device, wherein the isolated secondary converter circuit device is configured to operate according to the inactive state in response to receiving the first control signal.

[0025] The summary above is provided merely to summarize some exemplary embodiments to provide a basic understanding of some aspects of this disclosure. Therefore, it should be understood that the embodiments described above are merely illustrative and should not be construed as narrowing the scope or spirit of this disclosure in any way. It should also be understood that, in addition to the embodiments summarized herein, the scope of this disclosure covers many possible embodiments, some of which will be further described below. Attached Figure Description

[0026] Having thus provided a general description of some exemplary embodiments described in this disclosure, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:

[0027] Figure 1 An exemplary diagram is illustrated of a system configured to balance a flying capacitor in a high-power multilevel buck or boost converter for renewable and solar MPPT inverter applications, according to one or more embodiments of the present disclosure.

[0028] Figure 2 An exemplary diagram is illustrated of a system configured to balance the flying capacitor in a high-power multilevel buck converter for renewable and solar MPPT inverter applications, according to one or more embodiments of the present disclosure.

[0029] Figure 3 An exemplary diagram is illustrated of a system configured to balance the flying capacitor in a high-power multilevel boost converter for renewable and solar MPPT inverter applications, according to one or more embodiments of the present disclosure.

[0030] Figure 4A and Figure 4BAn exemplary graph is illustrated in the diagram of a flying capacitor voltage in a system configured to balance the flying capacitor in a high-power multilevel buck or boost converter for renewable and solar MPPT inverter applications, according to one or more embodiments of the present disclosure.

[0031] Figure 5 The illustration shows a flowchart of the operation of a system and method for supporting the balancing of flying capacitors in a high-power multilevel buck or boost converter for renewable and solar MPPT inverter applications, according to one or more embodiments of the present disclosure; and

[0032] Figure 6 Exemplary apparatuses for systems and methods supporting balanced flying capacitors in high-power multilevel buck or boost converters for renewable and solar MPPT inverter applications are illustrated according to one or more embodiments of the present disclosure. Detailed Implementation

[0033] Now, some embodiments of the present disclosure will be described more fully below with reference to the accompanying drawings, which illustrate some, but not all, embodiments of the present disclosure. In fact, various embodiments of the present disclosure may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure will satisfy applicable legal requirements. Similar reference numerals always refer to similar elements.

[0034] As used herein, the term "comprising" means including but not limited to and should be interpreted in the manner commonly used in the patent context. The use of broader terms such as comprises, includes, and having should be understood to support narrower terms such as constitutes, substantially constitutes, and substantially includes.

[0035] The phrases “in various embodiments,” “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally mean that the specific feature, structure, or characteristic following the phrase may be included in at least one embodiment of this disclosure, and may be included in more than one embodiment of this disclosure (importantly, such phrases do not necessarily refer to the same embodiment).

[0036] The term “example” or “exemplary” is used in this document to mean “serving as an example, instance, or illustration.” Any implementation described as “exemplary” in this document is not necessarily to be construed as being preferred or superior to other implementations.

[0037] If the specification states that a component or feature "may," "can," "will," "should," "will," "preferably," "possibly," "typically," "optionally," "for example," "often," or "maybe" (or other such language) include or have a characteristic, then the specific component or feature is not required to include or have that characteristic. Such a component or feature may be optionally included in some embodiments, or it may be excluded.

[0038] The use of the term "circuitary means" as used herein in relation to a component of a system or apparatus should be understood to include specific hardware configured to perform functions associated with a particular circuit means as described herein. The term "circuitary means" should be broadly understood to include hardware, and in some embodiments, includes software for configuring the hardware. For example, in some embodiments, "circuitary means" may include processing circuit means, communication circuit means, input / output circuit means, etc. In some embodiments, other elements may provide or supplement the functionality of a particular circuit means.

[0039] As used herein, the term "isolated converter circuit device" and the like refer to a converter circuit device comprising at least two parts, wherein there is no direct conduction path between the two parts of the circuit device. For example, an isolated converter circuit device may include an input stage and an output stage, wherein there is no direct conduction path between the input stage and the output stage. In some examples, the input stage and output stage of an isolated converter circuit device have separate grounds. Conversely, in a non-isolated converter circuit device, the input stage and output stage may share a common ground, allowing current to flow directly between the two parts. In some embodiments, isolation in an isolated converter circuit device is achieved using electrical insulation (such as air or a non-conductive material). In some embodiments, isolation is achieved by including a transformer in the circuit so that power is transmitted using electromagnetic energy.

[0040] As used herein, the term "charging a capacitor" and similar terms refer to providing equal and opposite voltages to the conductive plates of a capacitor that is in an uncharged or partially charged state, such that current flows to the conductive plates and generates a voltage across the capacitor with an amplitude substantially equal to the voltage provided. In some embodiments, the amplitude of the provided voltage is referred to as the target voltage. In some embodiments, the duration for which the capacitor is charged includes the time between a first time when current begins to flow from a voltage source providing voltage to the conductive plates of the capacitor and a second time when the voltage across the capacitor becomes equal to the amplitude of the voltage provided by the voltage source.

[0041] As used herein with respect to a circuit device or component in a system or apparatus, the term "default operating state" means the operating state to which the circuit initially operates and automatically returns to. In some embodiments, the circuit will continue to operate in the default operating state unless the circuit device is triggered to operate in an alternative state. In some such embodiments, the circuit device will continue to operate in the default operating state unless the circuit device receives a signaling that triggers the circuit device to operate in an alternative state. In some embodiments, if no signaling is received that triggers the circuit device to operate in an alternative state, the circuit device will automatically return to the default operating state. In some other embodiments, the circuit device will automatically return to the default operating state after operating in an alternative state for a pre-configured duration. In some embodiments, the default operating state includes converting a reference voltage to a target voltage and providing the target voltage to the conductive plates of a capacitor so that the capacitor can be charged to the target voltage.

[0042] As used herein with respect to a circuit device or component in a system or apparatus, the term "inactive state" means a state in which the circuit device ceases to perform one or more configured functions. In some embodiments, when an isolated converter circuit device operates under an inactive state, the isolated converter circuit device stops charging the capacitor to a target voltage.

[0043] As used herein with respect to a circuit device or component in a system or apparatus, the term "initialization" means causing the circuit device to begin performing one or more configured functions. In some embodiments, the circuit device operates according to a default operating state in response to initialization.

[0044] As used herein in relation to circuit devices or components in a system or apparatus, the term "open loop" refers to a circuit device that does not have a feedback loop and is not capable of monitoring and / or regulating the function of the circuit device based on its output.

[0045] Overview

[0046] Some renewable energy and high-voltage electric vehicle (EV) applications utilize operating voltages of approximately 800V and higher. Some power devices have relatively low operating voltages (such as approximately 650V or lower) and are therefore unsuitable for direct use in such applications. Other power devices have relatively high operating voltages (such as approximately 1200V or higher) and are suitable for direct use in renewable energy and high-voltage EV applications. However, such power devices are relatively expensive and can significantly increase costs for manufacturers.

[0047] In some cases, to reduce manufacturing costs and device stress in high-voltage applications, manufacturers may combine multilevel converters with low-voltage power devices. However, some multilevel converters are associated with hardware and software challenges. For example, some multilevel converters (such as multilevel buck and boost converters) rely on flying capacitors to provide an intermediate operating voltage that limits device stress to less than the source voltage (e.g., the maximum source voltage). Therefore, the flying capacitor voltage is constrained to half the source voltage (e.g., it must be half the source voltage). For example, the flying capacitor in a 3-level buck converter can be constrained to half the input voltage, while the flying capacitor in a 3-level boost converter can be constrained to half the output voltage. In some cases, if the flying capacitor voltage deviates from half the source voltage, the multilevel converter may be damaged. The source voltage may also be referred to herein as the reference voltage. For example, if the flying capacitor voltage drops below half the source voltage by a threshold amount (e.g., about 15% to 20%), the multilevel converter may suffer irreparable damage. Additionally, the flying capacitor, which serves as a dummy power supply for the multilevel converter's switches, can discharge during multilevel converter initialization, increasing device stress. In other words, the startup of a multilevel converter can be relatively complex because the initial discharge of the flying capacitor makes the voltage stress across the two switches destructive. Some systems can employ methods for balancing the flying capacitor. However, some methods for balancing the flying capacitor can be constrained to systems with two switches (such as two metal-oxide-semiconductor field-effect transistors (MOSFETs)) and two diodes. Therefore, such methods are incompatible with other multilevel systems (such as multilevel systems employing a four-switch design (e.g., a four-MOSFET design)).

[0048] Various aspects of this disclosure relate to improved systems, apparatuses, and methods for balancing flying capacitors in high-power multilevel converters, such as those used in renewable and solar MPPT inverter applications. Among other aspects, this disclosure provides improved systems, apparatuses, and methods for balancing flying capacitors in advanced digital power conversion applications, such as power conversion applications involving SiC multilevel converters (e.g., for power outputs greater than about 5 kilowatts (kW)).

[0049] According to various aspects of this disclosure, a system may include a secondary converter to balance one or more flying capacitors in a multilevel converter (such as a multilevel buck converter or a multilevel boost converter). In some embodiments, the secondary converter is configured to unconditionally and also balance the voltages of one or more flying capacitors during startup. A multilevel converter may include more than three levels. That is, in some embodiments, a multilevel converter includes any N-level converter where N is greater than or equal to 3. In some embodiments, the secondary converter may include an isolated, multi-output forward-derived converter configured to operate in an open-loop manner. For example, a secondary converter may be an example of a converter that uses a transformer to generate output voltages and provide isolation (e.g., current isolation) for a load. In some embodiments, the transformer may include multiple secondary windings to generate multiple output voltages, which may have the same or different values.

[0050] In some embodiments, this disclosure provides a system including a multilevel converter with a flying capacitor and a secondary converter configured to charge the flying capacitor to a target voltage (e.g., half of the source voltage) according to a default operating state. In some such embodiments, the secondary converter is configured to switch (switch only) from the default operating state to an inactive state in response to one or more events. Thus, in such embodiments, the secondary converter is configured to unconditionally and upon startup (e.g., in response to initialization) charge the flying capacitor to the target voltage.

[0051] In some embodiments, the system may include a microcontroller unit (MCU) configured to monitor (continuously monitor) the voltage across the flying capacitor while the multilevel converter is running. In some such embodiments, if the MCU determines that the voltage across the flying capacitor meets a threshold (e.g., equal to a target voltage), the MCU may use a control signal to trigger the secondary converter to switch from a default operating state to an inactive state. That is, the event may include the MCU determining that the voltage across the flying capacitor meets a threshold. In some embodiments, in response to determining that the voltage across the flying capacitor equals the target voltage, the MCU may generate (and output to the secondary converter) a control signal that triggers the secondary converter to switch to an inactive state, causing the secondary converter to stop charging the flying capacitor. That is, in some embodiments, the secondary converter is configured to run (e.g., always run) and stop running in response to receiving a control signal. In a non-limiting example, the secondary converter may be configured to stop running (e.g., simply stop running) if the secondary converter receives a control signal corresponding to a "HIGH" logic level.

[0052] Additionally, in some embodiments, if the MCU determines that the voltage across the flying capacitor does not meet a threshold (e.g., deviates from a target voltage), the MCU can trigger the secondary converter to operate for a relatively short period to balance the flying capacitor. In some such embodiments, the MCU can use another control signal to operate the secondary converter. Furthermore, in response to determining that the voltage across the flying capacitor is not equal to the target voltage, the MCU can generate (and output to the secondary converter) another control signal that triggers the secondary converter to switch to a default operating state, causing the secondary converter to restart operation and charge the flying capacitor to the target voltage. In a non-limiting example, the secondary converter can be configured to operate if it receives a control signal corresponding to a "low" logic level.

[0053] Alternatively, the secondary converter can be configured to operate if it does not receive a control signal corresponding to a high logic level. For example, the secondary converter can be configured to operate in response to the absence of a control signal corresponding to a high logic state, which could be due to, for example, the secondary converter not receiving a control signal and / or the MCU not generating (and outputting) a control signal to the secondary converter. In other words, the secondary converter can be configured to operate in the absence of a control signal corresponding to a high logic state. Therefore, the MCU can trigger the secondary converter to switch to a default operating state by preventing the generation (and / or output) of a control signal corresponding to a high logic state. By configuring the secondary converter to operate according to a default operating state and to switch (only switch) from the default operating state to an inactive state in response to a control signal corresponding to a high logic state, these systems and methods provide a secondary converter configured to balance a flying capacitor with or without MCU intervention. By providing a secondary converter configured to balance a flying capacitor with or without MCU intervention, these systems, apparatuses, and methods improve the reliability of multilevel converters, among other benefits.

[0054] Exemplary systems, methods, and apparatus

[0055] In this document, embodiments of the present disclosure include systems, methods, and apparatus for balancing flying capacitors in high-power multilevel buck or boost converters for renewable and solar MPPT inverter applications, which may be implemented in various embodiments.

[0056] Figure 1 An exemplary diagram of a system 100 configured to balance flying capacitors in a high-power multilevel buck or boost converter for renewable and solar MPPT inverter applications, according to one or more embodiments of the present disclosure, is illustrated.

[0057] like Figure 1 As illustrated in the example, system 100 includes an N-level converter circuit arrangement 104 (e.g., a multilevel converter) with a flying capacitor 106. In some embodiments, the N-level converter circuit arrangement 104 includes a 3-level converter with the flying capacitor 106 and four switches (e.g., S1, S2, S3, and S4). In some such embodiments, the flying capacitor 106 may be symmetrically positioned between at least two of the four switches. For example, the flying capacitor 106 may be symmetrically positioned between the four switches such that the flying capacitor 106 can be used as a dummy power source between the first two switches (e.g., S2 and S3), and / or the flying capacitor 106 can be used as a dummy power source between the last two switches (e.g., S1 and S4). The performance of the N-level converter circuit arrangement 104 may depend on the system 100's ability to maintain the voltage across the flying capacitor 106 at a target voltage. For example, if the voltage across the flying capacitor 106 deviates from the target voltage (i.e., becomes unbalanced), the N-level converter circuit arrangement 104 may be damaged. Furthermore, the flying capacitor 106 can be configured to discharge upon startup, thereby causing the capacitor to become unbalanced.

[0058] According to various aspects of this disclosure, system 100 includes a secondary converter circuit arrangement 102 configured to unconditionally and also balance the flying capacitor 106 upon startup. For example, the secondary converter circuit arrangement 102 may be an example of an isolated, multi-output forward-derived converter configured to operate in an open-loop manner. In some embodiments, the secondary converter circuit arrangement 102 is configured to charge the flying capacitor to a target voltage (e.g., half of the source voltage) according to a default operating state and to switch (switch only) from the default operating state to an inactive state in response to one or more events. Therefore, in some embodiments, the secondary converter circuit arrangement 102 is configured to unconditionally and also charge the flying capacitor 106 to a target voltage upon startup (e.g., in response to initialization).

[0059] like Figure 1As illustrated in the example, the secondary converter circuit device 102 may be an example of a converter whose transfer function such that the output voltage of the secondary converter (e.g., positive output voltage 112-a and negative output voltage 114-a, and positive output voltage 112-b and negative output voltage 114-b) is equal to 50% of the input voltage 116 leading to the secondary converter circuit device 102. In at least one embodiment, the secondary converter circuit device 102 is an open-loop, isolated forward converter. Alternatively, in at least one embodiment, the secondary converter circuit device 102 is a DC-DC converter unit that operates according to the duty cycle of a pulse width modulation (PWM) signal. For example, in some embodiments, the secondary converter circuit device 102 is an open-loop, isolated forward-derived DC-DC converter configured to operate with a 50% PWM duty cycle. In some embodiments, the switches in the N-level converter circuit device 104 are controlled via one or more PWM signals output from a PWM controller (not shown). In some such embodiments, the secondary converter circuitry 102 may be configured to operate in open loop with a 50% PWM signal duty cycle. In some such embodiments, the secondary converter circuitry 102 may be referred to as a PWM converter.

[0060] In some embodiments, isolation is achieved in the secondary converter circuit arrangement 102 by including a transformer within it. For example, as... Figure 1 As illustrated in the example, the secondary converter circuit arrangement 102 may include a transformer 120 that provides isolation between the input stage (e.g., input voltage 116) and the output stage (e.g., positive output voltage 112-a and negative output voltage 114-a and / or positive output voltage 112-b and negative output voltage 114-b). In some such embodiments, power is transferred between the input and output stages via electromagnetic energy. The transformer 120 includes a primary winding and one or more secondary windings 118 (e.g., secondary winding 118-a, secondary winding 118-b).

[0061] In some embodiments, the N-level converter circuit 104 is a 3-level converter with a single flying capacitor. In other words, in some embodiments, the N-level converter comprises a single unit. In some such embodiments, the secondary converter circuit arrangement 102 may be configured to include a secondary winding (e.g., secondary winding 118-a) such that the secondary converter can provide a positive output voltage 112-a and a negative output voltage 114-a to the conductive plate of the single flying capacitor for charging. In some other embodiments, the N-level converter circuit arrangement 104 comprises multiple units. In some such embodiments, the secondary converter circuit arrangement 102 may include multiple secondary windings (e.g., secondary windings 118-a and 118-b) such that the secondary converter circuit arrangement 102 can provide output voltages to multiple units (e.g., multiple flying capacitors among the multiple units) of the N-level converter circuit arrangement 102. For example, the N-level converter may be an example of a 5-level converter with two flying capacitors. In such an example, the secondary converter circuit can provide positive output voltage 112-a and negative output voltage 114-a to the conductive plate of the first flying capacitor (of the first unit), and can provide positive output voltage 112-b and negative output voltage 114-b to the conductive plate of the second flying capacitor (of the second unit).

[0062] In some embodiments, the output of the secondary converter circuit device 102 is floating. In other words, in some embodiments, the secondary converter circuit device 102 has one or more floating outputs that are rectified and output to one or more flying capacitors. Therefore, one or more outputs of the secondary converter circuit 102 can be equal to a target voltage. For example, the input voltage 116 can be equal to the source voltage such that the output voltage (e.g., the magnitude of each of the positive output voltage 112-a, negative output voltage 114-a, positive output voltage 112-b, and negative output voltage 114-b) is equal to 50% of the source voltage (i.e., the target voltage). In other words, the secondary converter circuit device 102 can use a transformer 120 to convert the source voltage (e.g., provided to the secondary converter circuit device 102 at the input node) into a target voltage provided to the flying capacitor, where the target voltage is equal to half the source voltage. In some embodiments, the output of the secondary converter circuit device 102 can be determined based on the turns ratio of the transformer 120 (and diodes 122-a and 122-b). Therefore, transformer 120 and diode 122 can be configured such that the output voltage of secondary converter circuit device 102 is equal to half of the input voltage to secondary converter circuit device 102. For example... Figure 1As illustrated in the example, the secondary converter circuit device 102 may include one or more other components (e.g., switches, capacitors, inductors, other diodes) to support one or more functions of the secondary converter circuit device 102.

[0063] In some embodiments, the secondary converter circuitry 102 is configured to switch from a default operating state to an inactive state in response to a control signal. For example, in some embodiments, system 100 includes an MCU 110 that can be configured to monitor the voltage across the flying capacitor 106. In some such embodiments, if the MCU 110 determines that the voltage across the flying capacitor 106 is equal to a target voltage, the MCU 110 can generate (and output to the secondary converter circuitry 102) a control signal 124 that triggers the secondary converter to switch to an inactive state, causing the secondary converter circuitry 102 to stop charging the flying capacitor 106. For example, the MCU 110 can generate and output a control signal corresponding to a "high" logic state. In other words, the MCU 110 can set the control signal 124 "high" to trigger the secondary converter circuitry 102 to switch to an inactive state, causing the secondary converter circuitry 102 to stop charging the flying capacitor 106. In some embodiments, the control signal 124 includes a strobe or enable signal. Additionally, in some embodiments, MCU 110 may prevent the generation (e.g., and / or output) of control signal 124. For example, secondary converter circuitry 102 may be configured to operate according to a default operating state in response to the absence of control signal 124. Therefore, MCU 110 may trigger secondary converter circuitry 102 to switch to the default operating state by preventing the generation (and / or output) of control signal 124. In some embodiments, MCU 110 may alternatively prevent the generation (and / or output) of control signal 124 by generating a control signal corresponding to a "low" logic state. In other words, MCU 110 may set control signal 124 "low" to trigger secondary converter circuitry 102 to switch to the default operating state, causing secondary converter circuitry 102 to charge flying capacitor 106. That is, in some embodiments, the secondary converter circuitry 102 may be configured to operate in an inactive state (e.g., a "OFF" state) when the control signal 124 is set high, and in a default operating state (e.g., an "ON" state) when the control signal 124 is low. Alternatively, in some embodiments, the secondary converter circuitry 102 may be configured to operate in an inactive state (e.g., a "OFF" state) when the secondary converter circuitry 102 does not receive a control signal corresponding to a high logic state (e.g., due to a malfunction of the MCU 110 or otherwise determining that no control signal corresponding to a high logic state is generated and / or output). In some embodiments, the control signal 124 is an example of a strobe or enable signal.

[0064] In some embodiments, by configuring the secondary converter to operate according to a default operating state when the control signal 124 is set low, and to operate in an inactive state (operating only in this state) when the control signal 124 is set high, the secondary converter can balance the flying capacitor with or without MCU intervention. Configuring the secondary converter to balance the flying capacitor with or without MCU intervention can improve the reliability of the multilevel converter, and has other benefits.

[0065] In some embodiments, MCU 110 may determine whether the voltage across flying capacitor 106 is equal to a target voltage based on one or more signals. For example, in some embodiments, system 100 includes a voltage sensing circuit 108 configured to sense (e.g., momentarily sense) the voltage across flying capacitor 106. For example, voltage sensing circuit 108 may be configured to acquire one or more signals 128 that indicate the voltage across flying capacitor 106. For example, signal 128 may include a first voltage (VTOP) associated with the high-voltage side of flying capacitor 106 and a second voltage (VBOT) associated with the low-voltage side of flying capacitor 106, and the voltage across flying capacitor may correspond to VTOP-VBOT. In some such embodiments, voltage sensing circuit 108 may use a differential amplifier (e.g., and one or more other components, such as one or more resistors and / or one or more capacitors) to obtain a sample of the voltage across flying capacitor based on signal 128. In other words, in some embodiments, voltage sensing circuit 108 includes a differential amplifier configured to sample the voltage across flying capacitor.

[0066] Voltage sensing circuitry 108 can output signal 126 to MCU 110 based on signal 128. Signal 126 may correspond to a sample of the voltage across the flying capacitor 106. In other words, voltage sensing circuitry 108 may include a differential amplifier configured to sample the voltage across the flying capacitor 106 and provide the sample to MCU 110 via signal 126. In some embodiments, the sampled voltage is proportional to the voltage across the flying capacitor 106. Additionally, in some embodiments, MCU 110 may be configured to obtain a signal indicating a source voltage from N-level converter circuitry 104. In some such embodiments, MCU 110 may compare the sampled voltage with the source voltage to determine whether the voltage across the flying capacitor 106 is equal to a target voltage. For example, the MCU may use the sampled voltage to determine the voltage (Vfly) across the flying capacitor and then determine whether the source voltage (Vcc) obtained from the N-level converter is twice the voltage across the flying capacitor (e.g., whether Vfly is half of Vcc). In some embodiments, the voltage sensing circuitry 108 can provide continuous monitoring of the voltage across the capacitor, which can lead to increased reliability and other benefits.

[0067] Figure 2 An exemplary diagram is shown of a system 200 configured to balance flying capacitors in a high-power multilevel buck converter for renewable and solar MPPT inverter applications, according to one or more embodiments of the present disclosure. System 200 may be... Figure 1 An example of system 100 is illustrated and referenced in the figure. For example, system 200 includes an N-level converter circuit device 204 having a flying capacitor 206. The N-level converter circuit device 204 can be configured to convert an input voltage 218 provided at a first node of the N-level converter circuit device 204 into an output voltage 234 provided at a second node of the N-level converter circuit device 204. The input voltage 218 can be supplied from a power source to the N-level converter circuit device 204, and the output voltage 234 can be supplied from the N-level converter circuit device 204 to a load 232.

[0068] like Figure 2 As illustrated in the example, the N-level converter circuit device 204 is configured to operate in buck mode. In other words, in various embodiments, the N-level converter is an N-level buck converter configured to reduce the input voltage. In some such embodiments, the input voltage 218 to the N-level converter circuit device 204 is higher than the output voltage 234 from the N-level converter circuit device 204 to the load 232. Figure 2As illustrated in the example, the N-level converter circuit device 204 includes a flying capacitor 206 and a plurality of switches 220 (e.g., switches 220-a, 220-b, 220-c, and 220-d). In some embodiments, the plurality of switches 220 are controlled via one or more PWM signals. For example, each of the plurality of switches 220 may be controlled via a corresponding PWM signal. The N-level converter circuit device 204 may include one or more other components, such as a shunt resistor 236, a plurality of equalizing resistors 222 (e.g., equalizing resistors 222-a, 222-b, 222-c, and 222-d), an inductor, and one or more capacitors, to support one or more functions of the N-level converter circuit device 204. In some embodiments, the N-level converter circuit device 204 may include an inductor current sensor 238 (inductor A current sensor) and an output current sensor 240 (Iout A current sensor).

[0069] According to various aspects of this disclosure, system 200 also includes a secondary converter circuit arrangement 202, which is configured to unconditionally and also balance the flying capacitor 206 during startup. The secondary converter circuit arrangement 202 may be via... Figure 1 The figure illustrates, and refers to, an example of a secondary converter circuit arrangement described therein. For example, secondary converter circuit arrangement 202 may be an example of an isolated, multi-output forward-derived converter configured to operate in an open-loop manner. In some embodiments, secondary converter circuit arrangement 202 is configured to charge flying capacitor 206 to a target voltage (e.g., half the source voltage) according to a default operating state, and to switch (switch only) from the default operating state to an inactive state in response to one or more events. Therefore, in some embodiments, secondary converter circuit arrangement 202 is configured to unconditionally and upon startup (e.g., in response to initialization) charge flying capacitor 206 to the target voltage.

[0070] In some embodiments, based on the N-level converter operating in buck mode, the auxiliary input voltage 216 to the secondary converter circuitry 202 may include or be otherwise set as the input voltage 218 to the N-level converter. In other words, because the input voltage 218 to the N-level converter circuitry 204 is higher than the output voltage 234 from the N-level converter circuitry 204, the auxiliary input voltage 216 to the secondary converter circuitry 202 is the same as the input voltage 218 to the N-level converter circuitry 204. For example, as... Figure 2As illustrated in the example, the secondary converter circuit 202 is configured to receive an auxiliary input voltage 216 from the input voltage 218 of the N-level converter circuit 204. Therefore, the output voltages from the secondary converter circuit 202 (e.g., positive output voltage 212 and negative output voltage 214) are equal to half the input voltage 218. The secondary converter circuit 202 can be configured to provide the positive output voltage 212 to the first (top) conductive plate of the flying capacitor 206 and the negative output voltage 214 to the second (bottom) conductive plate of the flying capacitor 206.

[0071] In some embodiments, such as Figure 2 As illustrated in the example, the secondary converter circuit device 202 (also known as an auxiliary converter) is configured to receive control signal 224 from MCU 210. MCU 210 can be... Figure 1 The diagram illustrates, and refers to, an example of an MCU described in the figure. For example, MCU 210 can set control signal 224 low (e.g., set the logic of control signal 224 to a low state) to enable the secondary converter circuit device 202 to operate. Alternatively, MCU 210 can set control signal 224 high (e.g., set the logic of control signal 224 to a high state) to disable the secondary converter circuit device 202. In other words, the secondary converter circuit device 202 can be configured to operate in response to the logic of control signal 224 being set low, and to stop operating in response to the logic of control signal 224 being set high.

[0072] In some examples, MCU 210 may set the logic of control signal 224 based on monitoring the voltage across flying capacitor 206. That is, in some embodiments, MCU 210 may be configured to sense input voltage 218 and the voltage of flying capacitor to determine whether the voltage of flying capacitor deviates from half of input voltage 218. In some embodiments, MCU 210 may use a sample of the flying capacitor voltage (e.g., VTOP-VBOT) to determine (e.g., measure) the voltage of flying capacitor. For example, system 200 may include voltage sensing circuitry 208. Voltage sensing circuitry 208 may be a device that senses voltage across the flying capacitor. Figure 1An example of a voltage sensing circuit device is illustrated and referenced in the figure. For example, voltage sensing circuit device 208 may be configured to sense (e.g., momentarily sense) the voltage across a flying capacitor 206. In some embodiments, voltage sensing circuit device 208 is configured to sense (e.g., measure) the voltage across a flying capacitor 206 by obtaining a first signal 228 indicating a first voltage (VTOP) associated with the high-voltage side of the flying capacitor 206 (e.g., the top conductive plate) and a second signal 230 indicating a second voltage (VBOT) associated with the low-voltage side of the flying capacitor 206 (e.g., the bottom conductive plate). In some embodiments, the voltage sensing circuit device may obtain the first signal 228 from node 242-a and the second signal 230 from node 242-b.

[0073] In some embodiments, the voltage sensing circuitry 208 can determine the voltage across the flying capacitor 206 based on the difference between a first voltage and a second voltage. That is, VTOP-VBOT can correspond to a measurement of the voltage across the flying capacitor 206. In some embodiments, the voltage sensing circuitry 208 can be configured to output a signal 226 to the MCU 210 based on the measured voltage. For example, signal 226 can indicate (e.g., correspond to) a sample of the voltage measured across the flying capacitor 206. In other words, the voltage sensing circuitry 208 can be configured to sample the voltage across the flying capacitor 206, wherein the sample is proportional to the voltage across the flying capacitor 206, and the voltage sensing circuitry can provide the sampled voltage to the MCU 210 via signal 226.

[0074] Alternatively, MCU 210 may measure input voltage 218. For example, in some embodiments, MCU 210 may be configured to obtain a signal indicating the input voltage 218 leading to N-level converter circuitry 204. In some embodiments, MCU 210 may sense the input voltage by reading the input voltage bus. That is, in some embodiments, the MCU may obtain a signal indicating the input voltage 218 from the input voltage bus.

[0075] Figure 3 An exemplary diagram of a system 300 configured to balance flying capacitors in a high-power multilevel boost converter for renewable and solar MPPT inverter applications, according to one or more embodiments of this disclosure. System 300 may be via... Figure 1An example of system 100 is illustrated and referenced in the figure. For example, system 300 includes an N-level converter circuit 304 having a flying capacitor 306. The N-level converter circuit 304 can be configured to convert an input voltage 318 provided at a first node of the N-level converter circuit 304 into an output voltage 334 provided at a second node of the N-level converter circuit 304. The input voltage 318 can be supplied from a power source to the N-level converter circuit 304, and the output voltage 334 can be supplied from the N-level converter circuit 304 to a load 332.

[0076] like Figure 3 As illustrated in the example, system 300 includes an N-level converter circuit device 204 configured to operate in boost mode. In other words, in various embodiments, the N-level converter is an N-level boost converter configured to increase the input voltage. In such an embodiment, the input voltage 318 to the N-level converter circuit device 204 is lower than the output voltage 334 from the N-level converter circuit device 304 to the load 332. Figure 3 As illustrated in the example, the N-level converter circuit device 304 may include a flying capacitor 306 and a plurality of switches 320 (e.g., switches 320-a, 320-b, 320-c, and 320-d). In some embodiments, the plurality of switches 320 are controlled via one or more PWM signals. For example, each of the plurality of switches 320 may be controlled via a corresponding PWM signal. The N-level converter circuit device 304 may include one or more other components, such as a plurality of equalizing resistors 322 (e.g., equalizing resistors 322-a, 322-b, 322-c, and 322-d), an inductor, and one or more capacitors, to support one or more functions of the N-level converter circuit device 304. In some embodiments, the N-level converter circuit device 304 may include an inductor current sensor 338 (inductor A current sensor) and an output current sensor 340 (Iout A current sensor).

[0077] According to various aspects of this disclosure, system 300 also includes a secondary converter circuit arrangement 302, which is configured to unconditionally and also balance the flying capacitor 306 during startup. The secondary converter circuit arrangement 302 may be via... Figure 1The figure illustrates, and refers to, an example of a secondary converter circuit arrangement described therein. For example, secondary converter circuit arrangement 302 may be an example of an isolated, multi-output forward-derived converter configured to operate in an open-loop manner. In some embodiments, secondary converter circuit arrangement 302 is configured to charge flying capacitor 306 to a target voltage (e.g., half the source voltage) according to a default operating state, and to switch (switch only) from the default operating state to an inactive state in response to one or more events. Therefore, in some embodiments, secondary converter circuit arrangement 302 is configured to unconditionally and upon startup (e.g., in response to initialization) charge flying capacitor 306 to the target voltage.

[0078] In some embodiments, based on an N-level converter operating in boost mode, the auxiliary input voltage 316 to the secondary converter circuitry 302 can be set (e.g., may include) the output voltage 334 of the N-level converter. In other words, because the output voltage 334 from the N-level converter circuitry 304 is higher than the input voltage 318 to the N-level converter circuitry 304, the auxiliary input voltage 316 to the secondary converter circuitry 302 is the same as the output voltage 334 from the N-level converter circuitry 304. For example, as... Figure 3 As illustrated in the example, the secondary converter circuit 302 is configured to receive an auxiliary input voltage 316 from the output voltage 334 of the N-level converter circuit 304. Therefore, the output voltage from the secondary converter circuit 302 (e.g., positive output voltage 312 and negative output voltage 314) is equal to half of the output voltage 334. The secondary converter circuit 302 can be configured to provide the positive output voltage 312 to the first (top) conductive plate of the flying capacitor 306 and the negative output voltage 314 to the second (bottom) conductive plate of the flying capacitor 306.

[0079] In some embodiments, such as Figure 3 As illustrated in the example, the secondary converter circuit 302 is configured to receive control signal 324 from MCU 210. MCU 310 can be... Figure 1 The diagram illustrates, and refers to, an example of an MCU described in the figure. For example, MCU 310 can set control signal 324 low (e.g., set the logic of control signal 324 to a low state) to enable the secondary converter circuit device 302 to operate. Alternatively, MCU 310 can set control signal 324 high (e.g., set the logic of control signal 324 to a high state) to disable the secondary converter circuit device 302. In other words, the secondary converter circuit device 302 can be configured to operate in response to the logic of control signal 324 being set low, and to stop operating in response to the logic of control signal 324 being set high.

[0080] In some examples, the MCU 310 can set the logic of the control signal 324 based on monitoring the voltage across the flying capacitor 306. For example, the system 300 may include a voltage sensing circuit device 308. The voltage sensing circuit device 308 may be a... Figure 1 An example of a voltage sensing circuit device is illustrated and referenced in the figure. For example, voltage sensing circuit device 308 may be configured to sense (e.g., momentarily sense) the voltage across a flying capacitor 306. In some embodiments, voltage sensing circuit device 308 is configured to sense (e.g., measure) the voltage across a flying capacitor 306 by obtaining a first signal 328 indicating a first voltage (VTOP) associated with the high-voltage side of the flying capacitor 306 (e.g., the top conductive plate) and a second signal 330 indicating a second voltage (VBOT) associated with the low-voltage side of the flying capacitor 306 (e.g., the bottom conductive plate). In some embodiments, voltage sensing circuit device 308 may obtain the first signal 328 from node 342-a and the second signal 330 from node 342-b.

[0081] In some such embodiments, the voltage sensing circuitry 308 can determine the voltage across the flying capacitor 306 based on the difference between a first voltage and a second voltage. That is, VTOP-VBOT can correspond to a measurement of the voltage across the flying capacitor 306. In some embodiments, the voltage sensing circuitry 308 can be configured to output a signal 326 to the MCU 310 based on the measured voltage. For example, the signal 326 corresponds to a sample of the voltage measured across the flying capacitor 306. In other words, the voltage sensing circuitry 308 can be configured to obtain a sample of the voltage across the flying capacitor 306 and provide the sample to the MCU 310 via the signal 326. In some embodiments, the sample is proportional to the voltage across the flying capacitor 306. The MCU 310 can also be configured to receive a signal from the N-level converter circuitry 304 that can indicate the output voltage 334. That is, the MCU 310 can be configured to sense the output voltage 334 and the voltage of the flying capacitor to determine whether the voltage of the flying capacitor deviates from half of the output voltage 334. The MCU 310 can sense the output voltage 334 by reading the output voltage bus. In other words, the MCU 310 can obtain a signal indicating the output voltage 334 from the output voltage bus.

[0082] Figure 4AAn exemplary graph 400-a is illustrated in a system configured to balance the flying capacitor in a high-power multilevel buck or boost converter for renewable and solar MPPT inverter applications, according to one or more embodiments of the present disclosure. Graph 400-a illustrates a voltage bus signal 402-a (Vbus) and a flying capacitor voltage signal 404-a (Vfly) as a function of time. Position 406-a in graph 400-a illustrates the change in flying capacitor voltage 404-a in response to a 50% reduction in system load (e.g., a 50% load reduction).

[0083] Figure 4B An exemplary graph 400-b is illustrated in a system configured to balance the flying capacitor in a high-power multilevel buck or boost converter for renewable and solar MPPT inverter applications, according to one or more embodiments of the present disclosure. Graph 400-b illustrates the voltage bus signal 402-b (Vbus) and the flying capacitor voltage signal 404-b (Vfly) as a function of time. Position 406-b in graph 400-b illustrates the change in flying capacitor voltage 404-b in response to a 50% increase in system load (e.g., a 50% load increase). In some embodiments, one or more systems and methods as described herein for balancing flying capacitors in a high-power multilevel buck or boost converter can provide a reduction in the slope of the flying capacitor voltage signal 404-a at position 406-a and the flying capacitor voltage signal 404-b at position 406-b, which can reduce (e.g., can prevent) uncontrolled imbalance of the flying capacitor and the likelihood of multilevel converter failure.

[0084] Figure 5 The illustration shows a flowchart 500 illustrating the operation of a system and method according to one or more embodiments of the present disclosure that supports balancing flying capacitors in high-power multilevel buck or boost converters for renewable and solar MPPT inverter applications. The operations in flowchart 500 can be performed in a system (such as via...) Figures 1 to 3 Implemented in the system described in the diagrams and with reference to these diagrams.

[0085] At operation 502, the MCU (or another suitable device) can at least initialize (e.g., start) the multilevel converter circuitry and the isolated secondary converter circuitry. The multilevel converter circuitry can be... Figures 1 to 3 Examples of multilevel converter circuit arrangements are illustrated and referenced in these figures. For example, a multilevel converter circuit arrangement may include at least a flying capacitor. Isolated secondary converter circuit arrangements (e.g., isolated multi-output forward-driving converters) may be... Figures 1 to 3Examples of secondary converter circuit arrangements are illustrated and referenced in these figures. For example, an isolated secondary converter circuit arrangement can be configured to charge a flying capacitor according to a default operating state in response to initialization.

[0086] At operation 504, the MCU can determine that the voltage across the flying capacitor meets a threshold. For example, the MCU can determine that the voltage across the flying capacitor is equal to half the source voltage.

[0087] At operation 506, the MCU can switch the isolated secondary converter circuitry from its default operating state to an inactive state based on the voltage meeting a threshold. For example, the MCU can cause the isolated secondary converter circuitry to operate in an inactive state, allowing it to stop charging the flying capacitor (e.g., to improve efficiency).

[0088] In a non-limiting example, when the multilevel converter circuitry and the isolated secondary converter circuitry are started up (e.g., initialized at operation 502), the MCU can operate the PWM controller for the multilevel converter circuitry (e.g., a PWM controller for outputting PWM signals to one or more switches of the multilevel converter circuitry) in a shutdown state. Alternatively, the MCU can set the control signal for the isolated secondary converter circuitry to a low state, allowing the isolated secondary converter circuitry to operate according to a default operating state (e.g., it can operate in an on state). In some embodiments, the isolated secondary converter circuitry is configured to operate at a 50% duty cycle associated with the PWM controller.

[0089] In some embodiments, within milliseconds of startup of the multilevel converter circuitry and the isolated secondary converter circuitry, the flying capacitor discharges (e.g., the voltage across the flying capacitor becomes 0V), and the voltage across one or more switches becomes half the source voltage. In some such embodiments, the voltage across one or more switches becomes half the source voltage based on one or more equalizing resistors (which can be on the order of approximately 500,000 Ω to prevent losses). Additionally, within milliseconds of startup of the multilevel converter circuitry and the isolated secondary converter circuitry, the isolated secondary converter circuitry, operating in the ON state and running at 50% duty cycle of a PWM controller due to a control signal being set low, charges the flying capacitor to half the source voltage.

[0090] In some embodiments, the MCU can measure the source voltage (e.g., via a voltage bus) and the voltage across the flying capacitor (e.g., via a voltage sensing circuit). In some such embodiments, at operation 504, the MCU can determine that the source voltage is equal to twice the voltage across the flying capacitor. In other words, the MCU can determine that the voltage across the flying capacitor is half the source voltage.

[0091] In some embodiments, at operation 506, in response to determining that the voltage across the flying capacitor is half of the source voltage, the MCU can operate the PWM controller in the on state and can set the control signal high to cause the isolated secondary converter circuitry to operate in an inactive state (e.g., in a off state that could cause an efficiency improvement).

[0092] In some embodiments, while the multilevel converter circuitry is running, the MCU may determine to set a control signal low in response to one or more events (to switch the isolated secondary converter circuitry from an inactive state to a default operating state). The MCU may set the control signal low to cause the isolated secondary converter circuitry to return to its default operating mode (e.g., restart) and charge the flying capacitor to half the source voltage (e.g., exactly half the source voltage). In some embodiments, the MCU may set the control signal low if it detects an increase in the output load of the multilevel converter circuitry or a decrease in the source voltage, causing the voltage across the flying capacitor to drop below a threshold voltage (e.g., less than half the source voltage). Alternatively, the control signal may be set low (e.g., forced low, off) if the MCU malfunctions and / or a watchdog event occurs. For example, the control pin may be released if the MCU malfunctions and / or a watchdog event occurs. In some embodiments, the MCU may set the control signal high after the voltage across the flying capacitor reaches half the source voltage to operate the isolated secondary converter circuitry in a shut-down state. Additionally, in some such embodiments, the MCU can restore normal PWM compensation.

[0093] In some embodiments, while the multilevel converter circuitry is running, the MCU may determine to set a control signal high in response to one or more other events (to switch the isolated secondary converter circuitry from a default operating state to an inactive state). The MCU may set the control signal high to stop the isolated secondary converter circuitry from charging the flying capacitor (e.g., to improve efficiency). For example, the MCU may detect an increase in the source voltage or a decrease in the output load, causing the voltage across the flying capacitor to exceed a threshold voltage (e.g., greater than half the source voltage). That is, during operation, the input voltage to the multilevel converter circuitry may suddenly increase or the load may suddenly decrease, causing the voltage across the flying capacitor to exceed the source voltage. In some such embodiments, the MCU may cause the PWM controller to operate in a shutdown state (e.g., all PWM switches may be temporarily stopped) for a few milliseconds. Additionally, the MCU may cause the isolated secondary converter circuitry to operate in an inactive state by setting the control signal high for a few milliseconds. In some embodiments, after setting the control signal high, the MCU can enable the PWM controller and operate according to a specific sequence, causing the equalization resistor in the multilevel converter circuit to drain the voltage across the flying capacitor to half of the source voltage. The MCU can then begin normal operation.

[0094] In some embodiments, by configuring the isolated secondary converter to operate in an inactive state in response to a control signal being set high, the flying capacitor can be unconditionally and during startup. In other words, startup and load transient balancing are unconditionally provided by the isolated secondary converter circuitry and the control signal. Therefore, the systems, apparatuses, and methods for balancing flying capacitors in high-power multilevel buck and boost converters as described herein can provide independent and reliable operation and startup of N-level converters.

[0095] For example, the performance of an N-level converter can depend on the voltage of the flying capacitor in the N-level converter being half the source voltage, and this disclosure provides systems, apparatuses, and methods for unconditionally balancing the flying capacitor voltage even in the event of an MCU failure or reset (e.g., due to a watchdog event). In some examples, flying capacitor balancing may be disturbed during startup and transient events, and the systems, apparatuses, and methods for balancing flying capacitors as described herein enable the flying capacitor to return to balance with or without MCU intervention. For example, according to one or more systems, apparatuses, and / or methods of this disclosure, an isolated secondary converter is configured to run (e.g., always run) and stop (e.g., stop only) if the MCU sets a control signal high. In some embodiments, these systems, apparatuses, and methods may also provide balancing resistors to balance the flying capacitor during extreme anomalies and / or protection events. These systems, apparatuses, and methods of this disclosure provide cost savings and a simplified code flow.

[0096] Figure 6 An exemplary device 600 is illustrated in accordance with one or more embodiments of the present disclosure, showing a system and method for supporting the balancing of flying capacitors in high-power multilevel buck or boost converters for renewable and solar MPPT inverter applications. Figure 6 It can be done Figures 1 to 3 , Figure 4A , Figure 4B and Figure 5 The illustrations and references to these figures depict one or more aspects of the implementation. Device 600 can be a device for an application, apparatus, and / or system. Device 600 can be a device for renewable and solar inverter MPPT applications, or a device for another application using a multilevel converter. For example, system 600 can be used for... Figures 1 to 3 The illustrated and referenced figures describe a system device. Device 600 may be a system and / or device including processor 602, memory 604, communication circuitry 606, input / output circuitry 608, and capacitor balancing circuitry 610, all of which may be connected via one or more buses 612. It should be understood that in some embodiments, device 600 may include or otherwise couple to one or more other components, such as a power supply and / or load. The power supply and / or load may be internal or external to device 600. For example, the power supply may be coupled to capacitor balancing circuitry 610 via a bus or one or more connectors. Alternatively, or additionally, the load may be coupled to capacitor balancing circuitry 610 via a bus or one or more connectors.

[0097] Although illustrated as a single block, processor 602 may include multiple components and / or processor circuitry. Processor 602 may be implemented as various components, including: one or more microprocessors with an accompanying digital signal processor; one or more processors without an accompanying digital signal processor; one or more coprocessors; one or more multi-core processors; processing circuitry; and various other processing elements. The processor may include integrated circuits. In various embodiments, processor 602 may be configured to execute applications, instructions, and / or programs stored in or otherwise accessible by processor 602. When executed by processor 602, these applications, instructions, and / or programs may enable the performance of one or more operations and / or functions described herein. Regardless of whether processor 602 is configured by hardware, firmware / software methods, or a combination thereof, it may include entities capable of performing operations and / or functions according to embodiments of this disclosure when correspondingly configured. For example, processor 602 may be configured to initialize multilevel converter circuitry 614 and / or secondary converter circuitry 616. Alternatively, processor 602 (e.g., in combination with memory 604 and / or voltage sensing circuitry 618) may be configured to determine that the voltage across the flying capacitor in multilevel converter circuitry 614 meets a threshold. Alternatively, processor 602 may be configured to switch secondary converter circuitry 616 from a default operating state to an inactive state based on the voltage meeting the threshold.

[0098] Memory 604 may include, for example, volatile memory, non-volatile memory, or some combination thereof. Although illustrated as a single block, memory 604 may include multiple memory components. In various embodiments, memory 604 may include, for example, random access memory, cache memory, flash memory, hard disk, circuitry configured to store information, or combinations thereof. Memory 604 may be configured to write or store data, information, application programs, instructions, etc., such that processor 602 can perform various operations and / or functions according to embodiments of the present disclosure. For example, in at least some embodiments, memory 604 may be configured to buffer or cache data for processing by processor 602. Additionally, or alternatively, in at least some embodiments, memory 604 may be configured to store program instructions for execution by processor 602. Memory 604 may store information in the form of static and / or dynamic information. The stored information may be stored and / or used by processor 602 when operations and / or functions are performed.

[0099] The communication circuitry 606 may be implemented as circuitry, hardware, a computer program product, or a combination thereof, configured to receive data from and / or send data to another component or device. The computer program product may use computer-readable program instructions stored on a computer-readable medium (e.g., memory) and executed by the processor 602. In various embodiments, the communication circuitry 606 (like other components discussed herein) may be at least partially implemented as part of or otherwise controlled by the processor 602. The communication circuitry 606 may communicate with the processor 602, for example, via a bus 612. Such a bus 612 may be connected to the processor 602, and it may also be connected to one or more other components of the processor 602. The communication circuitry 606 may include, for example, a transmitter, receiver, transceiver, network interface card, and / or supporting hardware and / or firmware / software, and may be used to establish communication with another component, device, and / or system. The communication circuit device 606 can be configured to receive and / or transmit data that can be stored in a memory by using one or more protocols, which can be used for communication between components, devices and / or systems.

[0100] Input / output circuitry 608 can communicate with processor 602 to receive instructions input by an operator and / or provide auditory, visual, mechanical, or other outputs to the operator. Input / output circuitry 608 may include supporting devices such as a keyboard, mouse, user interface, display, touchscreen display, lights (e.g., warning lights), indicators, speakers, and / or other input / output mechanisms. Input / output circuitry 608 may include one or more interfaces to which supporting devices can be connected. In various embodiments, aspects of input / output circuitry 608 may be implemented on a device used by the operator to communicate with processor 602. Input / output circuitry 608 may communicate, for example, via bus 612 with memory, communication circuitry 606, and / or any other components.

[0101] The capacitor balancing circuit device 610 can be achieved by at least Figures 1 to 3 Examples of systems, or portions thereof, described in these figures are illustrated and referenced. For example, capacitor balancing circuit device 610 may include multilevel converter circuit device 614, secondary converter circuit device 616, and voltage sensing circuit device 618, which may be through... Figures 1 to 3 , Figure 4A , Figure 4B and Figure 5Examples of corresponding circuit arrangements are illustrated and referenced in these figures. Multilevel converter circuit arrangement 614 may include a flying capacitor and multiple switches (e.g., four switches). Multilevel converter circuit arrangement 614 may be configured to operate in either a buck or boost mode. In some embodiments, voltage sensing circuit arrangement 618 may be configured to sense the voltage across the flying capacitor and (e.g., to processor 602) output a signal indicating the sensed voltage. In some embodiments, this signal includes a sample of the sensed voltage. Secondary converter circuit arrangement 616 may be an example of an isolated secondary converter (e.g., an isolated, multi-output forward derivation converter) configured to charge the flying capacitor to a target voltage according to a default operating state and switch from the default operating state to an inactive state in response to at least a first event. In some embodiments, secondary converter circuit arrangement 616 may be configured to operate according to a default operating state (e.g., always running) and stop (e.g., only stop) if secondary converter circuit arrangement 616 receives a control signal (e.g., a control signal set high).

[0102] Device 600 may be implemented in hardware, software, or a combination of hardware and software. In various embodiments, device 600 or portions thereof may be implemented in an integrated circuit, an MCU (e.g., a virtual machine running in an MCU), and / or the like. It should be readily understood that embodiments of the systems, apparatuses, and methods described herein may be configured in various additional and alternative ways beyond those explicitly described herein.

[0103] in conclusion

[0104] Operations and / or functions of this disclosure have been described herein, such as in the flowcharts. As will be understood, computer program instructions may be loaded onto a computer or other programmable means (e.g., hardware) to produce a machine, such that the resulting computer or other programmable means implements the operations and / or functions described in the boxes of the flowcharts herein. These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer, processor, or other programmable means to operate and / or function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture whose execution implements the operations and / or functions described in the boxes of the flowcharts. Computer program instructions may also be loaded onto a computer, processor, or other programmable means to cause a series of operations to be performed on the computer, processor, or other programmable means to produce a computer-implemented process, such that the instructions executing on the computer, processor, or other programmable means provide operations for implementing the functions and / or operations specified in the boxes of the flowcharts. The boxes of the flowcharts support combinations of means for performing the specified operations and / or functions, and combinations of operations and / or functions for performing the specified operations and / or functions. It will be understood that one or more boxes in a flowchart, as well as combinations of boxes in a flowchart, can be implemented by a computer system based on dedicated hardware or a combination of dedicated hardware and computer instructions that performs the specified operations and / or functions.

[0105] While this specification contains numerous details of specific embodiments and implementations, these should not be construed as limiting the scope of any disclosure or the scope that may be claimed, but rather as descriptions of features specific to a particular embodiment of a particular disclosure. Certain features described herein in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented separately or in any suitable sub-combination in multiple embodiments. Furthermore, while features may be described above as functioning in certain combinations and even initially stated so, in some cases one or more features in a declared combination may be removed from the combination, and the declared combination may involve sub-combinations or variations thereof.

[0106] Although operations and / or functions are illustrated in a specific order in the figures, this should not be construed as requiring the execution of such operations and / or functions in the shown specific order or sequential order, or the execution of all illustrated operations, to achieve the desired result. In some cases, alternative orders of operations and / or functions may be advantageous. In some cases, the actions set forth in the claims may be performed in a different order, still achieving the desired result. Therefore, while specific embodiments of the subject matter have been described, other embodiments are within the scope of the appended claims.

[0107] While this detailed description has illustrated some embodiments of the invention, the appended claims cover other embodiments of the invention that differ from the described embodiments according to various modifications and improvements.

[0108] In the appended claims, unless the specific terms “means for…” or “steps for…” are used within a given claim, they are not intended to be interpreted in accordance with paragraph 6 of §112 of 35 U.S.C.S.C.

Claims

1. A system comprising: A multilevel converter circuit device is configured to convert a first voltage provided at a first node into a second voltage provided at a second node, wherein the multilevel converter circuit device includes at least a flying capacitor and a plurality of switches coupled to the flying capacitor; as well as An isolated secondary converter circuit is configured to charge the flying capacitor to a target voltage according to a default operating state, wherein the isolated secondary converter circuit is configured to switch from the default operating state to an inactive state in response to at least a first event.

2. The system of claim 1, wherein the system further comprises a control circuit device configured to output a first control signal to the isolated secondary converter circuit device in response to detecting the first event, and wherein the isolated secondary converter circuit device is configured to operate according to the inactive state in response to receiving the first control signal.

3. The system of claim 2, wherein the control circuitry is configured to prevent the output of the first control signal to the isolated secondary converter circuitry in response to the detection of a second event, and wherein the isolated secondary converter circuitry is configured to operate according to the default operating state in the absence of the first control signal.

4. The system of claim 3, wherein the control circuitry is configured to prevent the output of the first control signal for a first duration, the first duration being at least partially based on a second duration, during which the isolated secondary converter circuitry charges the flying capacitor to the target voltage.

5. The system of claim 3, wherein the first event includes a voltage across the terminals of the flying capacitor satisfying a threshold associated with the flying capacitor, and wherein the second event includes the voltage not satisfying the threshold.

6. The system of claim 5, wherein the threshold is at least partially based on the target voltage.

7. The system of claim 1, wherein the isolated secondary converter circuitry is configured to operate in an open-loop manner.

8. The system of claim 1, wherein the isolated secondary converter circuitry is configured to charge the flying capacitor by converting a reference voltage provided at a third node into the target voltage, and wherein the reference voltage includes either the first voltage or the second voltage, which is at least partially based on the operating mode of the multilevel converter circuitry.

9. The system of claim 8, wherein the target voltage comprises half of the reference voltage.

10. The system of claim 8, wherein the first voltage is at least partially higher than the second voltage based on the multilevel converter circuit device operating according to a first operating mode, and wherein the reference voltage includes the first voltage, which is at least partially based on the first voltage being higher than the second voltage.

11. The system of claim 10, wherein the first operating mode includes a buck mode.

12. The system of claim 8, wherein the second voltage is at least partially based on the multilevel converter circuit device operating according to a second operating mode being higher than the first voltage, and wherein the reference voltage includes the second voltage, which is at least partially based on the second voltage being higher than the first voltage.

13. The system of claim 12, wherein the second operating mode includes a boost mode.

14. The system of claim 1, wherein the plurality of switches comprises at least four switches.

15. An apparatus comprising: At least one processor; as well as At least one memory, on which computer program code is stored, the computer program code, when executed by the at least one processor, causes the device to at least: Initialize at least a multilevel converter circuit device and an isolated secondary converter circuit device, wherein the multilevel converter circuit device includes at least a flying capacitor, and wherein the isolated secondary converter circuit device is configured to charge the flying capacitor according to a default operating state in response to initialization. Determine that the voltage across the capacitor meets a threshold. as well as The isolated secondary converter circuitry is switched from the default operating state to an inactive state, at least in part based on the voltage satisfying the threshold.

16. The apparatus according to claim 15, wherein, To switch the isolated secondary converter circuitry from the default operating state to the inactive state, the computer program code, when executed by the at least one processor, causes the device to at least: The control circuitry outputs a first control signal to the isolated secondary converter circuitry, wherein the isolated secondary converter circuitry is configured to operate according to the inactive state in response to receiving the first control signal.

17. The apparatus of claim 16, wherein the computer program code, when executed with the at least one processor, causes the apparatus to at least: Determining that the second voltage across the flying capacitor does not satisfy the threshold; and The isolated secondary converter circuitry is switched from the inactive state to the default operating state, at least in part, based on the fact that the second voltage does not meet the threshold.

18. The apparatus according to claim 17, wherein, To switch the isolated secondary converter circuitry from the inactive state to the default operating state, the computer program code, when executed by the at least one processor, causes the device to at least: The control circuitry is configured to prevent the output of the first control signal to the isolated secondary converter circuitry, wherein the isolated secondary converter circuitry is configured to operate according to the default operating state in the absence of the first control signal.

19. A method comprising: Initialize at least a multilevel converter circuit device and an isolated secondary converter circuit device, wherein the multilevel converter circuit device includes at least a flying capacitor, and wherein the isolated secondary converter circuit device is configured to charge the flying capacitor according to a default operating state in response to initialization. Determine that the voltage across the capacitor meets a threshold. as well as The isolated secondary converter circuitry is switched from the default operating state to an inactive state, at least in part based on the voltage satisfying the threshold.

20. The method of claim 19, wherein switching the isolated secondary converter circuitry from the default operating state to the inactive state comprises: The control circuitry outputs a first control signal to the isolated secondary converter circuitry, wherein the isolated secondary converter circuitry is configured to operate according to the inactive state in response to receiving the first control signal.

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