Controller for a power converter

Abstract

The present disclosure relates to a controller for a power converter for receiving an input voltage on a primary side and generating an output voltage on a secondary side, the power converter comprising a first primary side switch configured to be switchable between an on state and an off state, a second primary side switch configured to be switchable between an on state and an off state, and an energy transfer element configured to transfer energy from the input voltage to the secondary side. The controller is configured to operate in a first control state and a second control state.

Description

field

[0001] This disclosure relates to controllers for power converters. background

[0002] Consumers of electronic devices prefer universal fast chargers, which can efficiently charge a variety of devices, rather than having to carry multiple dedicated chargers for each device.

[0003] This requirement presents several engineering challenges, such as: Wide output voltage and power adaptability - the charger is preferably designed to support different voltage and power levels for different devices.

[0004] High power density - To maintain portability, the charger is preferably compact and lightweight.

[0005] Universal input compatibility (e.g., from 85V AC to 264V AC) - the charger is preferably designed to work reliably in different regions without the need for an additional adapter.

[0006] Preferably, the next-generation fast charger can efficiently handle a wide input voltage range, support multiple output power levels, and maintain high power density while optimizing energy efficiency. Overview

[0007] The aim is to provide an improved power converter system that can be used in charging applications.

[0008] According to a first aspect of this disclosure, a controller for a power converter is provided for receiving an input voltage on a primary side and generating an output voltage on a secondary side. The power converter includes a first primary-side switch configured to switch between an on state and an off state; a second primary-side switch configured to switch between an on state and an off state; and an energy transfer element configured to transfer energy from the input voltage to the secondary side. The controller is configured to operate in a first control state, wherein when operating in the first control state, the controller is configured to: i) switch the first primary-side switch to an on state for a first on duration, and ii) after the first on duration, switch each of the first primary-side switch and the second primary-side switch to an off state for a first off duration; and the controller is configured to operate in a second control state, wherein when operating in the second control state, the controller is configured to: i) switch the second primary-side switch to an on state for a second on duration, and ii) after the second on duration, switch each of the first primary-side switch and the second primary-side switch to an off state for a second off duration.

[0009] Optionally, the first control state is a first energy transfer state, and the second control state is a reset state.

[0010] Optionally, the first primary-side switch includes a first primary transistor and / or the second primary-side switch includes a second primary transistor.

[0011] Optionally, at least one of the first primary transistor and the second primary transistor is a field-effect transistor (FET), a bipolar junction transistor (BJT), or an insulated gate bipolar transistor (IGBT).

[0012] Optionally, the first disconnect duration is longer than the first connect duration.

[0013] Optionally, the controller is configured to operate in an auxiliary control state, wherein, when operating in the auxiliary control state, the controller is configured to: i) switch the first primary-side switch to the on state for an auxiliary on duration, and ii) switch each of the first primary-side switch and the second primary-side switch to the off state for an auxiliary off duration after the auxiliary on duration, or i) switch the additional switch to the on state for an auxiliary on duration, and ii) switch each of the first primary-side switch, the second primary-side switch, and the additional switch to the off state for an auxiliary off duration after the auxiliary on duration.

[0014] Optionally, when operating in the first control state, the controller is configured to switch each of the first primary side switch, the second primary side switch, and the auxiliary switch to the off state for a first off state for a first off state after a first on-duration, and when operating in the second control state, the controller is configured to switch each of the first primary side switch, the second primary side switch, and the auxiliary switch to the off state for a second off state for a second off state after a second on-duration.

[0015] Optionally, the auxiliary control state is the second energy transfer state.

[0016] Optionally, the controller is configured to apply the first control sequence by repeatedly cycling between i) operating in a first control state, ii) operating in an auxiliary control state, and iii) operating in a second control state.

[0017] Optionally, the controller is configured to, when the first control sequence is applied: i) switch from operating in the first control state to operating in the auxiliary control state, ii) switch from operating in the auxiliary control state to operating in the second control state, and iii) switch from operating in the second control state to operating in the first control state.

[0018] Optionally, the controller is configured to, when the first control sequence is applied: i) switch from operating in the first control state to operating in the auxiliary control state after the first disconnection duration has elapsed, ii) switch from operating in the auxiliary control state to operating in the second control state after the auxiliary disconnection duration has elapsed, and iii) switch from operating in the second control state to operating in the first control state after the second disconnection duration has elapsed.

[0019] Optionally, the controller is configured to apply a second control sequence by repeatedly cycling through: i) operating in the first control state; and ii) operating in the second control state; and / or by repeatedly cycling through: i) operating in the first control state; ii) operating in the auxiliary control state; and iii) repeatedly operating in the second control state for a plurality of second control state switching cycles; and / or by repeatedly cycling through: i) operating in the first control state; ii) repeatedly operating in the auxiliary control state for a plurality of auxiliary control state switching cycles; and iii) operating in the second control state; wherein: the controller is configured to switch between applying the first control sequence and applying one or more of the second, third, and fourth control sequences.

[0020] Optionally, the controller is configured to, when the second control sequence is applied, i) transition from operating in the first control state to operating in the second control state, and ii) transition from operating in the second control state to operating in the first control state, and / or, when the third control sequence is applied, i) transition from operating in the first control state to operating in the auxiliary control state, ii) transition from operating in the auxiliary control state to operating in the second control state, and iii) transition from repeatedly operating in the second control state to operating in the first control state, and / or, when the fourth control sequence is applied, i) transition from operating in the first control state to operating in the auxiliary control state, ii) transition from repeatedly operating in the auxiliary control state to operating in the second control state, and iii) transition from operating in the second control state to operating in the first control state.

[0021] Optionally, the controller is configured to, when the second control sequence is applied, i) transition from operating in the first control state to operating in the second control state after the first disconnect duration has elapsed, and ii) transition from operating in the second control state to operating in the first control state after the second disconnect duration has elapsed, and / or when the third control sequence is applied, i) transition from operating in the first control state to operating in the auxiliary control state after the first disconnect duration has elapsed, ii) transition from operating in the auxiliary control state to operating in the second control state after the auxiliary disconnect duration has elapsed, and iii) transition from repeatedly operating in the second control state to operating in the first control state after the last second disconnect duration of a plurality of second control state switching cycles has elapsed; and / or when the fourth control sequence is applied: i) transition from operating in the first control state to operating in the auxiliary control state after the first disconnect duration has elapsed; ii) transition from repeatedly operating in the auxiliary control state to operating in the second control state after the last auxiliary disconnect duration of a plurality of auxiliary control state switching cycles has elapsed; and iii) transition from operating in the second control state to operating in the first control state after the second disconnect duration has elapsed.

[0022] Optionally, the controller is configured to apply a first control sequence when the power converter is operating in discontinuous conduction mode (DCM), and / or apply a second control sequence when the power converter is operating in continuous conduction mode (CCM) or critical conduction mode (CRM).

[0023] Optionally, the first primary-side switch and the second primary-side switch are coupled at the first node, and the energy transfer element is coupled to the first node.

[0024] Optionally, the energy transfer element includes a transformer comprising a primary winding and a secondary winding, the primary winding being coupled to a first node.

[0025] Optionally, the primary winding of the transformer is configured to exchange energy with the input source and transfer energy to the secondary winding when the controller operates in one of the first control state, the second control state, and the auxiliary control state.

[0026] Optionally, the power converter includes a resonant tank.

[0027] Optionally, the first primary-side switch and the second primary-side switch are coupled in series between a first voltage terminal for receiving the input voltage and a second voltage terminal for receiving the reference voltage.

[0028] Optionally, the controller includes a first switch gate driver and a second switch gate driver, wherein the first switch gate driver is used to provide a first gate drive signal to drive the switching operation of a first primary-side switch, and the second switch gate driver is used to provide a second gate drive signal to drive the switching operation of a second primary-side switch.

[0029] Optionally, the controller includes a first switch gate driver for providing a first gate drive signal to drive a first primary-side switch switching operation, a second switch gate driver for providing a second gate drive signal to drive a second primary-side switch switching operation, and an additional switch gate driver for providing an additional gate drive signal to drive an additional switch switching operation.

[0030] Optionally, the controller includes a control core configured to provide a first control signal to the first switch gate driver and a second control signal to the second switch gate driver, wherein the first gate drive signal depends on the first control signal and the second gate drive signal depends on the second control signal.

[0031] Optionally, the controller includes a control core configured to provide a first control signal to the first switch gate driver, a second control signal to the second switch gate driver, and an additional control signal to the additional switch gate driver, wherein the first gate drive signal depends on the first control signal, the second gate drive signal depends on the second control signal, and the additional gate drive signal depends on the additional control signal.

[0032] Optionally, the controller includes a first control module and a second control module. The first control module includes a first gate switch driver and a second gate switch driver, and the second control module includes an additional gate switch driver.

[0033] Optionally, the first control module includes a first control core and a second control core. The first control core is configured to provide a first control signal to the first switch gate driver and a second control signal to the second switch gate driver. The second control core is configured to provide an additional control signal to the additional switch gate driver. The first gate drive signal depends on the first control signal, the second gate drive signal depends on the second control signal, and the additional gate drive signal depends on the additional control signal.

[0034] Optionally, the control core may include one or more logic circuits, application-specific integrated circuits (ASICs), and / or processors.

[0035] Optionally, the control core is configured to sense one or more parameters of the power converter and adjust the first and / or second control signals based on the sensed one or more parameters.

[0036] Optionally, one or more parameters include the input voltage, the output voltage, and the node voltage at the first node.

[0037] Optionally, the controller is configured to operate in an auxiliary control state, wherein, when operating in the auxiliary control state, the controller is configured to i) switch the first primary-side switch to the ON state for an auxiliary ON duration, and ii) after the auxiliary ON duration, switch each of the first primary-side switch and the second primary-side switch to the OFF state for an auxiliary OFF duration, by repeating a cycle between the following operations: i) operating in the first control state, ii) operating in the auxiliary control state, and iii) operating in the second control state.

[0038] Optionally, the controller is configured to apply a first control sequence by operating in an initial state before repeatedly cycling between operating in a first control state, operating in an auxiliary control state, and operating in a second control state, wherein the initial state is one of the first, auxiliary, and second control states and depends on one or more parameters sensed by the control core.

[0039] Optionally, one of the parameters is the node voltage at the first node, and the controller is configured to, when the first control sequence is applied, i) switch from operating in the auxiliary control state to operating in the second control state when the node voltage exceeds a maximum threshold, and / or ii) switch from operating in the second control state to operating in the first control state when the node voltage drops below a minimum threshold.

[0040] Optionally, the controller is configured to set one or more of the following based on one or more parameters sensed by the control core: a first on duration, a first off duration, a second on duration, a second off duration, an auxiliary on duration, and an auxiliary off duration.

[0041] Optionally, the energy transfer element includes a transformer having a primary winding and a secondary winding, the primary winding being coupled to a first node, and the power converter including a resonant slot having one or more resonant slot capacitors.

[0042] Optionally, the controller includes a first gate driver for providing a first gate drive signal to drive a switching operation of the first primary-side switch, a second gate driver for providing a second gate drive signal to drive a switching operation of the second primary-side switch, and a control core configured to provide a first control signal to the first gate driver and a second control signal to the second gate driver, wherein the first gate drive signal depends on the first control signal and the second gate drive signal depends on the second control signal, wherein the control core is configured to sense one or more parameters of the power converter and adjust the first and / or the second control signal based on the sensed one or more parameters.

[0043] Optionally, one or more parameters include the input voltage, the output voltage, the node voltage at the first node, the primary current of the transformer, and the voltage of the resonant slot capacitor.

[0044] Optionally, the controller is configured to set the auxiliary switching duration based on one or more of the output voltage, the primary current of the transformer, and the voltage of the resonant slot capacitor.

[0045] Optionally, the controller may include an additional switch, or the additional switch may be external to the controller and the power converter, or the power converter may include an additional switch.

[0046] Optionally, the first primary-side switch and the second primary-side switch are coupled at the first node. The energy transfer element includes a transformer, which includes a primary winding and a secondary winding. The primary winding is coupled to the first node, and an additional switch is coupled to the first node, or coupled to an auxiliary winding located on the primary side of the transformer, or coupled to the primary winding of the transformer, or coupled to the secondary winding of the transformer, or integrated in an isolated grounded side.

[0047] Alternatively, the power converter is a half-bridge converter or a full-bridge converter.

[0048] Alternatively, the power converter is a forward half-bridge converter.

[0049] Alternatively, the power converter is a forward resonant half-bridge converter.

[0050] According to a second aspect of this disclosure, a power converter system is provided, the power converter system including a power converter and a controller, the power converter being configured to receive an input voltage on a primary side and generate an output voltage on a secondary side, the power converter including a first primary-side switch configured to switch between an on state and an off state, a second primary-side switch configured to switch between an on state and an off state, and an energy transfer element configured to transfer energy from the input voltage to the secondary side, and the controller being configured to operate in a first control state, wherein when operating in the first control state, the controller is configured to i) switch the first primary-side switch to an on state for a first on duration, and ii) after the first on duration, switch each of the first primary-side switch and the second primary-side switch to an off state for a first off duration; and the controller is configured to operate in a second control state, wherein when operating in the second control state, the controller is configured to i) switch the second primary-side switch to an on state for a second on duration, and ii) after the second on duration, switch each of the first primary-side switch and the second primary-side switch to an off state for a second off duration.

[0051] It should be understood that, as understood by those skilled in the art, the power converter system of the second aspect may include the features set forth with respect to the first aspect, and may include other features as described herein.

[0052] According to a third aspect of this disclosure, a method for controlling a power converter is provided, the power converter being used to receive an input voltage on a primary side and generate an output voltage on a secondary side, the power converter comprising: a first primary side switch configured to switch between an on state and an off state; a second primary side switch configured to switch between an on state and an off state; and an energy transfer element configured to transfer energy from the input voltage to the secondary side; the method comprising: operating a controller in a first control state by: i) switching the first primary side switch to an on state for a first on duration; and ii) after the first on duration, switching each of the first primary side switch and the second primary side switch to an off state for a first off duration; and operating the controller in a second control state by: i) switching the second primary side switch to an on state for a second on duration; and ii) after the second on duration, switching each of the first primary side switch and the second primary side switch to an off state for a second off duration.

[0053] It should be understood that the third aspect of the approach may include the use and / or provision of features described in relation to the first or second aspect, and may include the use and / or provision of other features as described herein. Brief description of the attached diagram

[0054] The present disclosure is described in more detail below by way of example and with reference to the accompanying drawings, in which: Figure 1A This is a schematic diagram of a known active clamp flyback converter. Figure 1B This is a schematic diagram of a known asymmetric half-bridge flyback converter; Figure 2A This is a schematic diagram of a known forward half-bridge converter. Figure 2B This is a schematic diagram of a known forward zero-voltage switching multiresonant converter (US4857822). Figure 2C This is a schematic diagram of a known forward multiresonant power converter ("Development of a 500 W / 1 MHz resonant power supply" presented by O. da Luz, E. Dupuy, M. Rocher, D. Sadarnac and M. Perelle in Proceedings of Intelec 93: 15th International Telecommunications Energy Conference, Paris, France, 1993, pp.140-145 vol.1); Figure 3A This is a schematic diagram of a controller for a power converter according to a first embodiment of the present disclosure. Figure 3B This is a schematic diagram showing the switching states of a switch used in example operation of a controller and a power converter; Figure 4A This is a schematic diagram of a specific embodiment of the controller and power converter according to the second embodiment of the present disclosure. Figure 4B These are schematic diagrams of specific embodiments of the controller that can be implemented in any of the embodiments described herein. Figure 4C It is shown that... Figure 4A Timing diagrams of waveforms related to the actual implementation of the controller and power converter; Figure 5 yes Figure 4A A schematic diagram of the equivalent circuit of a forward resonant half-bridge converter during resonance. Figure 6A This is a flowchart outlining a three-state control method with sequential transitions in a repetitive loop. Figure 6B This is a flowchart outlining a three-state control method provided by the controller for different control sequences; Figure 7A This is a schematic diagram illustrating a specific implementation of the controller and power converter according to the third embodiment of this disclosure. Figure 7BThis is a schematic diagram illustrating a specific implementation of a power converter according to a fourth embodiment of the present disclosure, which can be used with any controller embodiment described herein. Figure 7C This is a schematic diagram illustrating a specific implementation of a power converter according to a fifth embodiment of the present disclosure, which can be used with any controller embodiment described herein. Figure 7D This is a schematic diagram illustrating a specific implementation of a power converter according to the sixth embodiment of this disclosure, which can be used with any controller embodiment described herein. Figure 7E This is a schematic diagram illustrating a specific implementation of a power converter according to the seventh embodiment of this disclosure, which can be used with any controller embodiment described herein. Figure 7F This is a schematic diagram illustrating a specific implementation of a power converter according to the eighth embodiment of this disclosure, which can be used with any controller embodiment described herein. Figure 7G This is a schematic diagram illustrating a specific implementation of a power converter according to the ninth embodiment of this disclosure, which can be used with any controller embodiment described herein. Figure 7H This is a schematic diagram illustrating a specific implementation of a power converter according to the tenth embodiment of this disclosure, which can be used with any controller embodiment described herein. Figure 7I This is a schematic diagram of a specific implementation of a power converter according to the eleventh embodiment of this disclosure, which can be used with any controller embodiment described herein; and Figure 8A This is a schematic diagram illustrating a specific embodiment of the controller and power converter according to the twelfth embodiment of the present disclosure. Figure 8B This is a schematic diagram illustrating a specific implementation of the controller according to the thirteenth embodiment of this disclosure. Figure 8C This is a schematic diagram illustrating another specific embodiment of the controller according to the fourteenth embodiment of the present disclosure. Figure 8D This is a flowchart outlining a three-state control method with sequential transitions in a repetitive loop. Figure 8E Is display and Figure 8A Timing diagrams of waveforms related to the actual implementation of the controller and power converter. Figure 8F This is a schematic diagram of a specific implementation of a power converter according to the fifteenth embodiment of this disclosure, which can be used with any of the controller embodiments described herein. Figure 8G This is a schematic diagram of a specific implementation of a power converter according to the sixteenth embodiment of this disclosure, which can be used with any controller embodiment described herein. Figure 8H This is a schematic diagram illustrating a specific implementation of a power converter according to the seventeenth embodiment of this disclosure, which can be used with any controller embodiment described herein. Figure 8IThis is a schematic diagram illustrating a specific implementation of a power converter according to the eighteenth embodiment of this disclosure, which can be used with any controller embodiment described herein. Figure 8J This is a schematic diagram of a specific implementation of a power converter according to the nineteenth embodiment of the present disclosure, which can be used with any controller embodiment described herein. Detailed description

[0055] Due to their simplicity and ability to provide current isolation, flyback converters are the dominant topology in fast chargers and power supplies. These converters operate as follows: 1. When the main switch is turned on, it receives energy from the input terminal and stores the energy in the transformer.

[0056] 2. When the main switch is turned off, energy is transferred to the secondary side.

[0057] However, this asynchronous energy reception / transfer (energy is received from the input and delivered to the secondary side at different times) results in: Transformers are large in size—because transformers must store energy, their core and winding designs limit power density.

[0058] Inefficiency – Energy storage and release result in additional losses.

[0059] Figure 1A This is a schematic diagram of a known active clamp flyback converter 100. Figure 1B This is a schematic diagram of a known asymmetric half-bridge flyback converter 102. Flyback converters 100 and 102 attempt to reduce transformer size and improve efficiency compared to other converters. However, these variations still use asynchronous energy reception / transfer, which fundamentally limits improvements in power density.

[0060] A forward converter is an alternative to a flyback converter. A forward converter synchronously transfers input energy to the secondary side, meaning that energy exchange from the input and energy delivery to the secondary side occur simultaneously. This reduces the need for large energy storage and associated power losses, thereby improving power density and efficiency.

[0061] Figure 2A This is a schematic diagram of a known forward half-bridge converter 200. The forward half-bridge converter is characterized by two switches (main switch Q2 and reset switch Q1), which together form a half-bridge on the primary side of transformer 202.

[0062] Still Figure 2A The image shows the gate signal waveform of each of the switches Q1 and Q2. A high signal indicates that the corresponding switch is turned on and allows current to flow, while a low signal indicates that the corresponding switch is turned off and prevents current from flowing.

[0063] When the main switch Q2 is turned on, energy can be directly transferred to the secondary side. The reset switch Q1 is responsible for resetting the transformer windings to prevent core saturation.

[0064] A significant variation of the forward half-bridge converter is the resonant forward half-bridge converter, which enhances the standard topology by incorporating multiple resonant components, such as capacitors and inductors, into a resonant slot to achieve zero-voltage switching (ZVS).

[0065] Figure 2B This is a schematic diagram of a known forward zero-voltage switching multivibrator 204 (US4857822). Figure 2C This is a schematic diagram of a known forward multiresonant power converter 206 (published by O. Da Luz, E. Dupuy, M. Rocher, D. Sadarnac and M. Perelle in Proceedings of Intelec 93:15th International Telecommunications Energy Conference, Paris, France, 1993, pp. 140-145 vol.1, "Development of a 500 W / 1 MHz resonant power supply").

[0066] These forward resonant half-bridge converters can be defined as follows: they include a first primary-side switch, a second primary-side switch, and a transformer coupled to a node between these switches; and in at least one operating state, the primary winding of the transformer exchanges energy with the input source and simultaneously transfers energy to the secondary winding.

[0067] Given that the design of forward converters 204 and 206 is based on a half-bridge structure combined with a resonant slot, this type of converter can be called a "forward resonant half-bridge converter".

[0068] The main switch and reset switch operate alternately (i.e., switch Q2 is turned on, then switch Q1 is turned on, then switch Q2 is turned on again, and this sequence is repeated, such as...). Figure 2A The traditional switch control method shown in the figure cannot guarantee the ZVS of the primary side switch under various operating conditions.

[0069] Zero-voltage switching (ZVS) is desirable for efficient power converter operation because turning on the switch when the applied voltage is zero or near zero minimizes power dissipation (since power loss is voltage × current). Without ZVS, switching losses increase, thus reducing efficiency and power density.

[0070] It is desirable to provide a forward resonant half-bridge converter with a wide input / output voltage range and variable power level, wherein both primary-side switches have zero-voltage switching (ZVS) during power transfer or transformer winding reset.

[0071] Figure 3A This is a schematic diagram of a controller 300 for a power converter 302 according to a first embodiment of the present disclosure. During operation, the power converter 302 receives an input voltage Vin at the primary side 304 and generates an output voltage Vout at the secondary side 306.

[0072] The controller 300 and the power converter 302 can form a power converter system.

[0073] The power converter 302 includes primary-side switches 308 and 310, each of which can switch between an ON and an OFF state. When in the ON state, the switch allows current to flow, while when in the OFF state, the switch restricts current flow.

[0074] The term "on" switch can refer to generating a control signal that controls the gate driver, causing the switch to establish a low-impedance connection (i.e., a resistance below a predefined threshold) between its terminals. Conversely, "off" switch can refer to generating a control signal that controls the gate driver, causing the switch to transition to an electrically isolated state, characterized by a resistance exceeding a predefined threshold, except for a small leakage current.

[0075] Each of the primary-side switches 308 and 310 may include a transistor, such as a field-effect transistor (FET), a bipolar junction transistor (BJT), or an insulated gate bipolar transistor (IGBT).

[0076] The power converter 302 also includes an energy transfer element 312 configured to transfer energy from the input voltage Vin at the primary side 304 of the power converter 302 to the secondary side 306 of the power converter 302. The energy transfer element 312 may include a transformer.

[0077] During operation, the controller 300 functions to switch the state of the primary-side switches 308 and 310 in such a way that energy is transferred from the input voltage Vin to the secondary side 306 via the energy transfer element 312 to generate the output voltage Vout.

[0078] The controller 300 is configured to operate in a first control state and a second control state. The first control state can be an energy transfer state, in which the controller 300 operates switches 308 and 310 to transfer energy to the secondary side via energy transfer element 312. The second control state can be a reset state, in which the controller 300 operates switches 308 and 310 to reset energy transfer element 312.

[0079] Figure 3B This is a schematic timing diagram showing the switching states of switches 308 and 310 for example operation of controller 300 and power converter 302.

[0080] Trace 308a displays the state of primary side switch 308, and trace 310a displays the state of primary side switch 310. A high state indicates that the corresponding switch is in the ON state, and a low state indicates that the corresponding switch is in the OFF state.

[0081] In the first control state (marked "State 1"), the controller 300 is configured to switch the primary side switch 308 to the ON state for a first ON duration ton1, and then switch each of the primary side switches 308, 310 to the OFF state for a first OFF duration tooff1. The first OFF duration tooff1 may be greater than the first ON duration ton1.

[0082] In the second control state (marked as "state 2"), the controller 300 is configured to switch the primary side switch 310 to the on state for a second on duration ton2, and then switch each of the primary side switches 308, 310 to the off state for a second off duration tooff2.

[0083] In this example, the controller 300 operates in a first control state, then in a second control state, and cycles back and forth between the two states to provide the necessary control operations for the power converter 302. It should be understood that in other embodiments, the controller 300 may operate in one or more additional control states besides the two control states shown in this example.

[0084] The power converter 302 can be, for example, a half-bridge converter or a full-bridge converter. The power converter 302 can be a forward half-bridge converter. The power converter 302 can be a resonant half-bridge converter.

[0085] Figure 4A This is a schematic diagram of a specific embodiment of the controller 300 and power converter 302 according to the second embodiment of the present disclosure.

[0086] In this embodiment, the power converter 302 is a resonant half-bridge converter. Primary-side switches 308 and 310 are coupled at node N1, which is coupled to the energy transfer element 312. In this embodiment, the energy transfer element 312 includes a transformer 400, which includes a primary winding 402 coupled to node N1 and a secondary winding 404.

[0087] Primary-side switch 310 is a high-side switch (also labeled Q1), and primary-side switch 308 is a low-side switch (also labeled Q2). In the schematic diagram, primary-side switches 308 and 310 are both implemented as MOSFETs. However, as mentioned earlier, alternative transistor types can be used in other embodiments.

[0088] For clarity in the diagram, the markings for the primary and secondary sides have been omitted. Those skilled in the art should understand that the primary and secondary sides are separated by windings 402 and 404 of transformer 400.

[0089] Power converter 302 includes a resonant tank 406. The resonant tank 406 may include one or more resonant tank capacitors. In this example, the resonant tank 406 includes resonant tank capacitors 408 and 410 and leakage inductance 412 of transformer 400. In another embodiment, the resonant tank 406 may include an additional external inductor connected in series with leakage inductance 412. Inductor 414 represents the inductance of transformer 400.

[0090] The resonant slot 406 (which may be referred to as the “resonant network”) plays a role in shaping the performance of the power converter 302 by defining multiple resonant periods that affect the switching characteristics.

[0091] In this example, primary-side switches 308 and 310 are coupled in series between a first voltage terminal for receiving input voltage Vin and a second voltage terminal for receiving a reference voltage (such as ground).

[0092] The series coupling of the primary-side switch 310, which acts as the high-side switch, and the primary-side switch 308, which acts as the low-side switch, forms a half-bridge structure between the DC input voltage (Vin) and a reference voltage (such as ground). In scenarios where the input power supply is an AC voltage (such as mains power used in power supply applications), a rectifier circuit (such as a diode bridge rectifier) ​​can be incorporated to convert the AC voltage to the desired DC input voltage Vin.

[0093] The power converter 302 may also include a capacitor C in Inductor L r2 Output capacitor Co, capacitor C r3 Switch Q3 and resistor R L .

[0094] Switch Q3 can be a secondary-side active control switch, which in another embodiment can be replaced by a diode.

[0095] The primary winding 402 of transformer 400 is connected to double resonant capacitors 408 and 410 (also labeled C). r1 and C r2 It is coupled to ground and input voltage Vin. The capacitances of resonant capacitors 408 and 410 can be equal or different, depending on the specific design requirements. Node N1 is the midpoint node between primary-side switches 308 and 310 and serves as the connection point to the opposite end of the primary winding 402.

[0096] Transformer 400 includes a secondary winding 404, wherein the winding polarity is indicated by dots, following standard industry practice. In this particular embodiment, the primary winding 402 and the secondary winding 404 are wound in the same direction. The secondary winding 404 is connected to an inductor L. r2 The inductor L supplies power to the output terminal. r2 It can be an integrated component of an external inductor or transformer 400, or a combination of both.

[0097] Switch Q3 couples the second terminal of secondary winding 404 to ground. Capacitor C r3 (It can be an external capacitor) or the parasitic capacitance of switch Q3, or a combination of both, connected in parallel with switch Q3.

[0098] Additionally, the output capacitor Co is placed between the output terminal at the output voltage Vout and ground, thus acting as a filter together with the inductor Lr2 to stabilize the output voltage Vout.

[0099] In other embodiments of this disclosure, additional conventional components typically found in forward half-bridge converters (particularly forward resonant half-bridge converter circuits) may be integrated. These may include protection mechanisms such as overcurrent protection, voltage clamping diodes for the resonant capacitor, and feedback control functions.

[0100] The controller 300 can be configured to operate in an auxiliary control state. When operating in the auxiliary control state, the controller 300 is configured to switch the primary-side switch 308 to the ON state for an auxiliary ON duration, and after the auxiliary ON duration, switch each of the first primary-side switch 308 and the second primary-side switch 310 to the OFF state for an auxiliary OFF duration. The auxiliary control state can be another energy transfer state.

[0101] The primary winding 402 of transformer 400 can exchange energy with an input source (e.g., input voltage Vin) while transferring energy to the secondary winding 404, while controller 300 is operating in one of the first control state, second control state, and auxiliary control state.

[0102] Because of parasitic capacitance in transistor switches (such as primary-side switches 308, 310), unwanted energy loss can occur when the switch transitions from open to closed when a voltage is applied across its terminals. To mitigate these losses, some embodiments can implement zero-voltage switching (ZVS), where switching occurs when the applied voltage is close to or at zero. To facilitate ZVS, controller 300 can be configured to ensure that a switch remains on for a specific duration across three control states, thereby influencing the voltage condition prior to the next switching event.

[0103] Figure 4B This is a schematic diagram of a specific embodiment of the controller 300, which may be implemented in any of the embodiments described herein as understood by those skilled in the art.

[0104] The controller 300 includes a gate driver 420 for providing a first gate drive signal LO to drive the switching operation of the primary-side switch 308; and a gate driver 422 for providing a second gate drive signal HO to drive the switching operation of the primary-side switch 310.

[0105] The controller 300 may further include a control core 424 configured to provide a first control signal to the gate driver 420, wherein the first gate drive signal provided by the gate driver 420 depends on the received first control signal. The control core 424 is also configured to provide a second control signal to the gate driver 422, the second gate drive signal depending on the second control signal.

[0106] The control core 424 may include one or more logic circuits, application-specific integrated circuits (ASICs), processors, and / or other control-related components.

[0107] When the control core 424 includes one or more processors, they can be programmed via a dedicated computer program stored on a tangible storage medium. The control core 424 can receive multiple sensing signals (Sns_1, ..., Sns_n) via input terminals (which may be referred to as "Sns input pins"). These input signals may include: -Based on Vhb (the voltage at node N1), Figure 4A The Chinese character is represented as "V". hb The signal derived from 》.

[0108] - Information related to the input voltage Vin.

[0109] - Data regarding the required or actual output voltage (e.g., Figure 4A Vout in (the part).

[0110] -Any additional sensing signal typically used for forward converters or other voltage converters.

[0111] Based on these sensed inputs, the control core 424 can drive the gate driver 422 to generate power for the high-side switch (primary-side switch 310, in...). Figure 4A The gate drive signal HO (also labeled Q1) is output by the gate driver 420, and the gate driver 420 can output a signal for the low-side switch (primary-side switch 308, in...) Figure 4A The gate drive signal LO (also labeled Q2) is used. This control strategy ensures that the forward resonant half-bridge converter 302 operates effectively to maintain the desired output voltage Vout.

[0112] Figure 4C Is display and Figure 4A Timing diagrams of waveforms related to the actual implementation of the controller 300 and power converter 302.

[0113] Figure 4C A set of waveforms is provided to illustrate the corresponding signal behavior in this embodiment. It should be understood that these graphs are for conceptual representation purposes, and the actual waveforms may vary depending on the specific implementation details.

[0114] Figure 4C The waveforms include: - Gate drive signals HO, LO: --The topmost graph shows the gate drive signals HO (for primary-side switch 310, also labeled Q1) and LO (for primary-side switch 308, also labeled Q2).

[0115] --The solid line pulse represents the LO signal controlling Q2, while the dashed line pulse represents the HO signal controlling Q1.

[0116] --A high status indicates that the corresponding switch is on, while a low status indicates that the switch is off.

[0117] -Transformer current (i Lr1 i Sec ) and input current (i in ): -- marked i Lr1 The graph shows the primary side current I flowing through the primary winding 402 of transformer 400. Lr1 And marked i Sec The graph shows the secondary side current i supplied to the output. Sec .

[0118] --Input current i in This represents the input current from Vin.

[0119] -Resonant capacitor voltages (VC1, VC2): --Voltage waveform V C1 It is the voltage across the resonant capacitor 408, and the voltage waveform V C2 It is the voltage across the resonant capacitor 410.

[0120] -V at the midpoint of the half-bridge hb and its sensing signal (V) hb_sns ): --V hb The waveform corresponds to the voltage at node N1, the midpoint between primary-side switches Q1 and Q2.

[0121] --V hb_sns The sensing signal closely follows V hb Besides its lower amplitude due to reduced compression, it is also lower in amplitude.

[0122] --V hb_sns It is directed to the Sns input pin of controller 300 ( Figure 4B One of them, where it plays a role in the timing control for switching primary side switches 308, 310.

[0123] --Isolation methods (e.g., auxiliary windings on the core of a forward converter transformer) or non-isolation methods (e.g., resistive voltage dividers, or voltage dividers via current-limiting resistors) can be used to reduce V0. hb Transformed into inflow S ns The current signal from one of the input pins) is based on V hb Derive V hb_sns .

[0124] During operation, the controller 300 can apply the first control sequence by repeating the following cycle: 1. Operate in the first control state (state 1); 2. Operate in auxiliary control state (state A); and 3. Operate in the second control state (state 2).

[0125] While applying the first control sequence, the controller 300 can operate in the first control state before transitioning to the auxiliary control state, and then operate in the second control state before looping back to the first control state and repeating the sequence.

[0126] When the first control sequence is applied, a transition from the first control state to the auxiliary control state can occur after the first disconnection duration has elapsed; a transition from the auxiliary control state to the second control state can occur after the auxiliary disconnection duration has elapsed; and a transition from the second control state to the first control state can occur after the second disconnection duration has elapsed.

[0127] In a specific embodiment, the power switches (primary-side switches 308, 310) can operate in discontinuous conduction mode (DCM).

[0128] The first control sequence comprises three distinct states that transition sequentially in a repetitive loop. The initial state of the loop can be any of the three states (state 1, state A, state 2). Each state comprises two actions: (1) one of the primary-side switches 308 and 310 is turned on for a specific duration, which can be determined by the control logic provided by the control core 424 and the current state; and (2) both primary-side switches 308 and 310 are subsequently turned off for a defined time period.

[0129] In the DCM, the timing of the action used to switch between these three states can be affected by sensing signals (such as those represented by Sns_1, ..., Sns_n) received by the controller 300, which can be sensed by the power converter 302.

[0130] This embodiment has been described in conjunction with a DCM. However, alternative operating modes may be used in other embodiments. For example, a DCM may be particularly suitable for scenarios where the power converter 302 supplies relatively low output power or when a lower output voltage is required.

[0131] The detailed description of the tri-state switching method provided by the controller 300 in this embodiment can be summarized as follows: State 1: Energy Transfer In state 1, the operation includes two key actions: 1. Turn on the primary side switch 308 (also marked Q2) for a defined on-time duration (which may be referred to as the "first on-time duration").

[0132] 2. Disconnect the two primary side switches 308 and 310 (also labeled Q1 and Q2) for a defined disconnect duration (which may be referred to as the “first disconnect duration”).

[0133] like Figure 4A As shown, primary-side switch 308 is a low-side switch, and the second primary-side switch 310 is a high-side switch. Turning on primary-side switch 308 directly initiates energy transfer from the input terminal to the secondary side of transformer 400. Figure 4C At time t0, the midpoint voltage Vhb Approaching zero allows for zero-voltage switching (ZVS) or buck switching of the primary-side switch 308, thereby minimizing switching losses. The corresponding LO pulse in state 1 indicates that the primary-side switch 308 is turned on.

[0134] During state 1, energy from the input terminal can be directly transferred to the load via the resonant capacitor 408, which connects the primary winding 402 to the input terminal via the primary-side switch 308. Figure 4C As shown, the input current i in and secondary side current i Sec Maintaining synchronization in state 1 indicates simultaneous energy exchange from the input to the output. This is a unique feature of the forward resonant converter. Additionally, during state 1 of this forward resonant half-bridge converter, transformer 400 enters resonant mode, and current i... Lr1 The waveform from time t0 to time t1 is sinusoidal. This resonance involves multiple resonant components within the resonant slot 406.

[0135] Figure 5 yes Figure 4A A schematic diagram of the equivalent circuit 500 of the forward resonant half-bridge converter 302 during resonance. (From transformer inductance L) m The angle represents the equivalent circuit of the component at resonance, such as... Figure 5 As shown.

[0136] Therefore, based on the above equivalent circuit, the resonant period can be expressed as: (1) From time t2 to time t3, the first disconnect duration begins, temporarily suspending energy transfer to the secondary side 404 of the transformer. This prevents excessive energy delivery, thus enabling stable operation over a wide power and output voltage range. This pause in energy transfer during the first disconnect duration is particularly beneficial under low output power conditions. Therefore, during light load periods, the first disconnect duration can be significantly longer than the first turn-on duration. At V hb_sn When s reaches or approaches its local minimum, state 1 ends, thereby signaling the optimal switching point for re-energizing the primary-side switch 308 in the subsequent state A. State A: Auxiliary reset transformer winding

[0137] In state A, the following actions occur: 1. Turn on the primary side switch 308 (also marked Q2) for the auxiliary on duration (which may be referred to as the "auxiliary conduction duration").

[0138] 2. Disconnect the two primary side switches 308 and 310 (also labeled Q1 and Q2) for the auxiliary disconnect duration (which may be referred to as the "auxiliary shutdown duration").

[0139] State A serves as an auxiliary phase to facilitate the reset of transformer 400 winding in State 2, thereby ensuring that the reset switch (primary-side switch 310) achieves zero-voltage switching (ZVS). The reset winding is a requirement for forward converters.

[0140] refer to Figure 4A Reconnecting the primary-side switch 308 facilitates the energy transfer from the input source to the resonant slot 406, thereby ensuring that the transformer 400 winding is reset via zero-voltage switching (ZVS) during state 2.

[0141] exist Figure 4C In the middle, the corresponding LO pulse controls the primary-side switch 308, thereby pulling the tank current i. Lr1 The energy of this current comes directly from the input voltage Vin (e.g., Figure 4A i in in (As shown). This operation generates a voltage oscillation of Vhb, which assists the ZVS of the primary-side switch 310 in subsequent state 2.

[0142] After the auxiliary on-time (from time t3 to time t4), there is an auxiliary off-time (from t4 to time t5). During this period, the input current from Vin raises Vhb to near Vin. Once Vhb approximately reaches Vin, the voltage across the primary-side switch 310 is minimized, thereby reducing energy loss when the primary-side switch 310 is on in state 2. State A ends at time t5, transitioning converter 302 to state 3. State 2: Transformer reset and voltage balance

[0143] In state 2, the following actions occur: 1. The primary side switch 310 (also marked Q1) is turned on for the second on duration (which may be referred to as the "second conduction duration").

[0144] 2. Disconnect the two primary side switches 308 and 310 (also labeled Q1 and Q2) for a second disconnect duration (which may be referred to as the "second disconnect duration").

[0145] At time t5, state 2 begins with the primary-side switch 310 (high-side switch) turned on for the second on-time duration. This step ensures proper reset of the transformer 400 windings, thereby preventing saturation while maintaining... Figure 4A The voltage balance between the dual resonant capacitors 408 and 410 is shown.

[0146] During the second disconnection duration (times t6 to t7), Vhb decreases, and the associated energy is recirculated back to the input Vin. As Vhb approaches ground, the voltage across the primary-side switch 308 is minimized, thus facilitating low-loss switching in state 1 of the next cycle. At time t7, state 2 ends, and the control method transitions back to state 1, initiating a new cycle.

[0147] It should be understood that although the loop description begins with state 1, the initial state of the loop can vary to any of state 1, state A, or state 2 based on system conditions. Control core 424 can use sensing signals (Sns_1…Sns_n) to determine the starting state of the control operation loop, or set a default starting state accordingly. The loop can end in any of the three states (state 1, state A, or state 2).

[0148] Figure 6A This is a flowchart outlining a three-state control approach that sequentially transitions in a repetitive loop, where each state includes two key actions: 1. One of the primary switches (Q1 or Q2) is turned on for a defined duration, which can be determined by the control core 424.

[0149] 2. The two primary-side switches (Q1 and Q2) are disconnected for a specific period of time before transitioning to the next state.

[0150] In another embodiment, the controller 300 can be configured to apply different control sequences, which may depend on, for example, different operating conditions of the controller.

[0151] In summary, for a specific embodiment, the control core 424 can control the switch driver 420 and switch driver 422 of the controller 300. The control logic of the control core 424 for these two drivers 420 and 422 is as follows: The control logic has three states. These three states transition sequentially into a repeating loop: state 1 transitions to state A, state A transitions to state 2, and state 2 transitions back to state 1. The default start state of the loop can be set to any of the three states (state 1, state A, or state 2). The loop can end in any of the three states (state 1, state A, or state 2).

[0152] Figure 6B This is a flowchart outlining the three-state control method provided by controller 300 for different control sequences. The first control sequence is as previously referenced. Figure 6A As described.

[0153] The controller 300 can be configured to apply a second control sequence by repeatedly cycling between operating in a first control state (state 1) and operating in a second control state (state 2). This sequence omits the auxiliary state (state A). Figure 6B It is marked as "Optional 2".

[0154] In summary, the controller 300 can optionally bypass state A and transition directly from state 1 to state 2 before transitioning back to state 1.

[0155] Option 2 can be used for the high-power operating modes of the power converter 302 (Continuous On-Mode (CCM) or Critical On-Mode (CRM)). When the converter 302 needs to deliver higher output power, the controller 300 can bypass state A and transition directly from state 1 to state 2 before cycling back to state 1. This configuration enables operation in either CCM or CRM, which occurs at the boundary between CCM and DCM.

[0156] The control core 424 can be based on the input Sns_1…Sns_n (e.g. Figure 4B (As shown in the diagram) the timing of enabling the optional feature is dynamically determined. In another embodiment, the control mode setting may follow pre-configured enabling logic.

[0157] In summary, when the power converter 302 operates in DCM mode, the controller 300 may apply a first control sequence and / or when the power converter 302 operates in CCM mode or CRM mode, the controller 300 may apply a second control sequence.

[0158] The controller 300 can be configured to apply a third control sequence by repeatedly cycling between two or more switching cycles: operating in a first control state (state 1), operating in an auxiliary control state (state A), and repeating operation in a second control state (state 2) before returning to state 1. This sequence... Figure 6B The middle part is marked as "option 3".

[0159] In summary, this involves executing state 2 multiple times (>1 time) before transitioning to state 1. This approach ensures proper transformer reset or serves other functional purposes (such as balancing the voltage of the double resonant capacitor (V)). C1 and V C2 The control core 424 can monitor one or more sensing signals (Sns_1...Sns_n, such as...). Figure 4B As shown in the diagram, it detects incomplete winding reset or unbalanced double resonant capacitor voltage and determines whether to enable the feature. It can dynamically determine the number of times state 2 should be repeated, or simply follow a preset execution count.

[0160] The controller 300 can be configured to apply a fourth control sequence by operating in a first control state (state 1) before returning to state 1, repeating operation for two or more switching cycles in an auxiliary control state (state A) before transitioning to the second control state (state 2), and then repeating the cycle between operating in the second control state (state 2). This sequence... Figure 6B The middle part is marked as "Optional 1".

[0161] In summary, this involves executing state A multiple times (>1 time) before transitioning to state 2. This approach is particularly beneficial during startup with short switch-on durations or under low-load conditions. Repeating state A ensures that the bootstrap capacitor C... in Fully charge to the required voltage level necessary to drive the high-side switch (primary-side switch 310). The control core 424 can be based on Sns_1…Sns_n (e.g.,…Sns_n ... Figure 4B (As shown in the diagram) The number of times state A should be repeated can be dynamically determined, or it can simply follow a preset execution count.

[0162] The control core 424 can be configured to sense one or more parameters of the power converter 302 (as indicated by the sensing signals Sns_1, ..., Sns_n), and adjust one or two of the control signals provided to the gate drivers 420, 422 based on the sensed parameters.

[0163] The one or more parameters may include: input voltage Vin, output voltage Vout, node voltage VHB at node N1, transformer primary current, and resonant slot capacitor voltage.

[0164] In a specific embodiment, the initial state of the repeating sequence can be selected based on one or more sensing parameters.

[0165] The controller 300 can be configured to switch from operating in the auxiliary control state to operating in the second control state when the node voltage VHB at node N1 exceeds the maximum threshold when the first control sequence is applied, and / or switch from operating in the second control state to operating in the first control state when the node voltage VHB at node N1 drops below the minimum threshold.

[0166] In summary, in a specific embodiment, when the voltage at node N1 is at or near its local minimum, the control logic of the control core 424 can start state 1 and then start state A.

[0167] In summary, in a specific embodiment, when the voltage at node N1 is at or near its local maximum value, the control logic of the control core 424 can activate state 2.

[0168] The controller 300 can be configured to set one or more of the on-time or off-time for each state based on one or more sensing parameters.

[0169] The auxiliary on-time duration can be set based on one or more of the output voltage Vout, the transformer primary current, and the resonant slot capacitor voltage.

[0170] In summary, in a specific embodiment, the control logic of the control core 424 can adjust the first on-time based on the input signal of the voltage at the indicator node N1.

[0171] In summary, in a specific embodiment, the control logic of the control core 424 can adjust the first disconnect duration based on an input signal indicating the output condition (e.g., output voltage Vout) and an input signal indicating the voltage at node N1.

[0172] In a specific embodiment, the first disconnection duration can be significantly longer than the first connection duration.

[0173] In summary, in a specific embodiment, the control logic of the control core 424 can adjust the auxiliary connection duration based on the input signal indicating the input voltage Vin and the input signal indicating the voltage at node N1.

[0174] In summary, in a specific embodiment, the control logic of the control core 424 can adjust the second on-time based on the input signal indicating the primary side current of the transformer or the voltage of the resonant slot capacitor, combined with the input signal indicating the output condition.

[0175] Figure 7A This is a schematic diagram illustrating a specific implementation of the controller 300 and power converter 302 according to a third embodiment of the present disclosure. As will be understood by those skilled in the art, the controller 300 can be configured to function substantially as described with respect to any of the controller embodiments described herein to control the power converter 302.

[0176] In this embodiment, the power converter 302 is a forward resonant half-bridge converter. During operation, the power converter 302 receives an AC input voltage VACIN, which can vary between approximately 80V and 264V AC to accommodate different regional mains voltages. This AC voltage is processed by a filter stage 700 and a rectifier stage 702 to convert it into a DC input voltage Vin.

[0177] In another embodiment, a signal representing the value of VACIN can be provided to the controller 300 via an input pin, while a voltage divider at another input pin of the controller 300 can provide information about Vin.

[0178] In some embodiments, a power factor correction (PFC) circuit may also be included and implemented using conventional methods.

[0179] The controller 300 can manage the operation of the primary side switch 310 (high-side switch Q1) and the primary side switch 308 (low-side switch Q2) based on the three-state control method as described above.

[0180] In a specific embodiment, the controller 300 can be used in Figure 6A and / or Figure 6B The control method described herein adjusts the primary-side switches 308 and 310, and can generate a similar effect to that described in [the original text]. Figure 4C The switching signals of those signals shown in the image.

[0181] Through the controlled operation of primary-side switches 308 and 310, energy is transferred to the primary winding 402 of transformer 400. On the secondary side, the output voltage (Vout) is derived from the secondary winding 404 of transformer 400, and this output voltage can be rectified using a synchronous rectifier (SR) circuit, which may include synchronous rectifier switches controlled by a synchronous rectifier controller. A filter capacitor smooths the rectified voltage.

[0182] The sensing signal VHB_SNS can be obtained by connecting the VHB pin to the VHB_SNS pin via a current-limiting resistor 704. This signal can be used to determine the timing and duration of the switching pulses. Additionally, the output voltage Vout can be fed back to the controller 300 via an optocoupler 706 to provide current isolation. This feedback signal received at the FB input of the controller 300 can be used to adjust the pulse duration in the switching sequence, thereby ensuring stable operation.

[0183] It should be understood that other embodiments of this disclosure may exclude certain components described in any of the embodiments described herein, or may replace them with alternatives.

[0184] Although the described method is applied to forward resonant half-bridge converters with dual resonant capacitors, the principle extends to other variations of the forward resonant half-bridge topology.

[0185] Figure 7B This is a schematic diagram of a specific embodiment of the power converter 302 according to the fourth embodiment of this disclosure, which can be used with any of the controller 300 embodiments described herein, as understood by those skilled in the art.

[0186] Figure 7CThis is a schematic diagram of a specific embodiment of the power converter 302 according to the fifth embodiment of this disclosure, which can be used with any of the controller 300 embodiments described herein, as understood by those skilled in the art.

[0187] Figure 7D This is a schematic diagram of a specific embodiment of the power converter 302 according to the sixth embodiment of this disclosure, which can be used with any of the controller 300 embodiments described herein, as understood by those skilled in the art.

[0188] Figure 7E This is a schematic diagram of a specific embodiment of the power converter 302 according to the seventh embodiment of this disclosure, which can be used with any of the controller 300 embodiments described herein, as understood by those skilled in the art.

[0189] Figure 7F This is a schematic diagram of a power converter 302 according to the eighth embodiment of the present disclosure, which can be used with any of the controller 300 embodiments described herein, as understood by those skilled in the art.

[0190] Figure 7G This is a schematic diagram of a specific embodiment of the power converter 302 according to the ninth embodiment of this disclosure, which can be used with any of the controller 300 embodiments described herein, as understood by those skilled in the art.

[0191] Figure 7H This is a schematic diagram of a specific embodiment of the power converter 302 according to the tenth embodiment of this disclosure, which can be used with any of the controller 300 embodiments described herein, as understood by those skilled in the art.

[0192] Figure 7I This is a schematic diagram of a power converter 302 according to the eleventh embodiment of the present disclosure, which can be used with any of the controller 300 embodiments described herein, as understood by those skilled in the art.

[0193] Figures 7A-7I An example of a forward resonant half-bridge converter that converts input voltage Vin to output voltage Vout is shown. Although the controller operation described by controller 300 is primarily based on a half-bridge converter, the disclosed three-state control method can also be applied to a full-bridge converter, where two switches in one arm replicate the gate drive signals of diagonal switches in the opposite arm. Furthermore, the disclosed control method is adaptable, allowing features from different variations to be combined into a custom converter design while still benefiting from the proposed three-state switch control strategy.

[0194] It should be understood that, in other embodiments, the transformer secondary-side diodes may be replaced by active controlled switches (such as FETs, BJTs, or IGBTs).

[0195] It should be understood that although the embodiments described herein primarily relate to forward resonant half-bridge converters including dual resonant capacitors, other embodiments can be applied to other types of power converters, as will be understood by those skilled in the art.

[0196] Further embodiments of this disclosure can be applied, for example, to other forward half-bridge converters that include a transformer. Specifically, further embodiments can be applied to power converter configurations in which two primary-side switches coupled to the transformer windings are controlled by different signals to alternately energize and demagnetize the transformer, thereby facilitating power transfer to the secondary side.

[0197] Figure 8A This is a schematic diagram illustrating a specific embodiment of the controller 300 and power converter 302 according to the twelfth embodiment of this disclosure. Figure 6A As an alternative to the sequence outlined herein, controller 300 can control auxiliary switch 800 during auxiliary control state, instead of controlling primary-side switch 308.

[0198] According to the understanding of the technicians, the control of the auxiliary switch 800 in the auxiliary control state can provide the same or substantially similar results as previously described for the control of the primary side switch 308 during the auxiliary control state.

[0199] In this embodiment, while operating in the auxiliary control state, the controller 300 is configured to switch the auxiliary switch 800 to the on state for an auxiliary on duration, and after the auxiliary on duration, switch each of the primary side switch 308, the primary side switch 310, and the auxiliary switch 800 to the off state for an auxiliary off duration.

[0200] Additionally, when operating in the first control state, the controller 300 can be configured to switch each of the primary side switch 308, primary side switch 310, and auxiliary switch 800 to the off state for a first off state duration after a first on duration, and when operating in the second control state, the controller 300 can be configured to switch each of the primary side switch 308, primary side switch 310, and auxiliary switch 800 to the off state for a second off state duration after a second on duration.

[0201] Figure 8B This is a schematic diagram illustrating a specific embodiment of the controller 300 according to the thirteenth embodiment of this disclosure. For example, Figure 8BThe controller 300 can be used with a power converter system having an additional switch 800 for auxiliary control states.

[0202] The controller 300 in this example includes an additional gate driver 802 for providing an additional gate drive signal ZVS_G to drive the switching operation of an additional switch 800. The control core 424 provides additional control signals to the additional gate driver 802, wherein the additional gate drive signal ZVS_G depends on the received additional control signals.

[0203] Figure 8C This is a schematic diagram of another specific embodiment of the controller 300 according to the fourteenth embodiment of this disclosure. For example, Figure 8C The controller 300 can be used with a power converter system having an additional switch 800 for auxiliary control states.

[0204] The controller 300 in this embodiment includes a control module 804 and a control module 806. The control module 804 includes a first switch gate driver and a second switch gate driver (not shown) and a first control core (not shown) for the first switch gate driver and the second switch gate driver. The control module 806 includes an additional switch gate driver (not shown) and a second control core (not shown) for the additional switch gate driver.

[0205] Figure 8D This is a flowchart outlining a three-state control approach that sequentially transitions in a repetitive loop, where each state includes two key actions: 1. The duration for which one of the switches 308, 310, and 800 is turned on is defined, and this duration can be determined by the control core 424.

[0206] 2. Before transitioning to the next state, all switches 308, 310, and 800 are disconnected for a specific period of time.

[0207] Additional switch 800 is referred to as the "third switch" in the flowchart.

[0208] Figure 8E Is display and Figure 8A Timing diagrams of waveforms related to the actual implementation of the controller 300 and power converter 302. Waveform markings are as follows. Figure 4C As described. Figure 8E Example waveforms for the disclosed three-state control logic are shown, where state A is implemented by switch 800 (ZVS switch), and switch 800 is driven by ZVS_G.

[0209] Figure 8EA set of waveforms is provided to illustrate the corresponding signal behavior in this embodiment. It should be understood that these graphs are for conceptual representation purposes, and the actual waveforms may vary depending on the specific implementation details.

[0210] State A can be executed not only by the primary-side switch 308, but also by (e.g.) Figure 8A The third switch (i.e., the ZVS switch) shown in switch 800 is activated.

[0211] In this context, the disclosed three-state control logic can be implemented by a controller system comprising one or more control modules. For example, Figure 8B The disclosed three-state control logic, implemented by a single controller, is shown. This three-state control logic includes control logic for a third switch gate driver (gate driver 3) having an output labeled ZVS_G to drive switch 800.

[0212] Similarly, Figure 8C The disclosed three-state control logic is demonstrated using a controller system with two control modules 804 and 806. In this configuration, the control logic for state A (and the additional gate driver 802) for three-state control is implemented in the controller's control module 806.

[0213] The output of gate driver 802, labeled ZVS_G, drives additional switch 800. Control modules 804 and 806 can share the same ground or operate with different grounds. Communication between control modules 804 and 806 in the system is optional.

[0214] In another embodiment, the first switch driver 420, the second switch driver 422, and the third switch driver 802 are not integrated into a single controller or distributed across multiple controllers. They can also be implemented as discrete circuits outside the controller 300 and can function as independent switch drivers.

[0215] In summary, for the specific embodiment, the control core 424 can control the switch drivers 420, 422, and 802 of the controller 300. The control logic of the control core 424 for these three drivers 420, 422, and 802 is as follows: The control logic has three states. These three states transition sequentially into a repeating loop: state 1 transitions to state A, state A transitions to state 2, and state 2 transitions back to state 1. The default start state of the loop can be set to any of the three states (state 1, state A, or state 2). The loop can end in any of the three states (state 1, state A, or state 2).

[0216] The auxiliary switch 800 can be integrated into the controller 300 in the power controller system, or located on the primary side of the transformer 400, or on the secondary side of the transformer 400, or on the third winding side of the transformer 400, or on the isolated ground side. If the auxiliary switch 800 is located on the secondary side of the transformer 400, the auxiliary switch 800 can also be turned on for synchronous rectification when the current on the secondary side is not zero in state 1 and / or state 2.

[0217] In another embodiment, the controller 300 may be configured to use an additional switch 800 for auxiliary control states to implement as referenced. Figure 6B The described optional control schemes.

[0218] In summary, controller 300 may optionally execute state A multiple times before transitioning to state 2. Alternatively, controller 300 may optionally bypass state A and transition directly from state 1 to state 2 before transitioning back to state 1. Finally, controller 300 may optionally execute state 2 multiple times before transitioning to state 1.

[0219] In summary, when the voltage at node N1 is at or near its local minimum, the control logic of control core 424 can start state 1 and then start state 2.

[0220] In summary, when the voltage at node N1 is at or near its local maximum value, the control logic of control core 424 can activate state 2.

[0221] In summary, the control logic of the control core 424 can adjust the first on-time based on the input signal of the voltage at the indicator node N1.

[0222] In summary, the control logic of the control core 424 can adjust the first disconnect duration based on the input signal indicating the output condition and the input signal indicating the voltage at node N1.

[0223] In a specific embodiment, the first disconnection duration can be significantly longer than the first connection duration.

[0224] In summary, the control logic of the control core 424 can adjust the auxiliary on-time based on the input signal indicating the input voltage Vin and the input signal indicating the voltage at node N1.

[0225] In summary, the control logic of the control core 424 can adjust the second conduction duration based on the input signal indicating the primary side current of the transformer or the voltage of the resonant slot capacitor, combined with the input signal indicating the output condition.

[0226] In a specific embodiment, under at least one control operation state, the primary winding of transformer 400 is operable to exchange energy with an input source while transferring energy to the secondary winding 404.

[0227] Figure 8F This is a schematic diagram of a power converter 302 according to the fifteenth embodiment of this disclosure, which can be used with any of the controller 300 embodiments described herein, as understood by those skilled in the art.

[0228] In this embodiment, Q3 (additional switch 800) is integrated within the primary-side controller 300. Zero-voltage switching (ZVS) in state 2 is achieved by discharging the resonant tank through Q3 in state A using a resistor or resistor-capacitor circuit.

[0229] Figure 8G This is a schematic diagram of a power converter 302 according to the sixteenth embodiment of the present disclosure, which can be used with any of the controller 300 embodiments described herein, as understood by those skilled in the art.

[0230] In this embodiment, Q3 (additional switch 800) is located outside the primary-side controller 300. Zero-voltage switching (ZVS) in state 2 is achieved by discharging the resonant tank through Q3 in state A using a resistor or resistor-capacitor circuit.

[0231] Figure 8F and Figure 8G This demonstrates how to achieve ZVS in state 2 by discharging the resonant tank through Q3 in state A using a resistor or resistor-capacitor circuit.

[0232] Figure 8H This is a schematic diagram of a power converter 302 according to the seventeenth embodiment of the present disclosure, which can be used with any of the controller 300 embodiments described herein, as understood by those skilled in the art.

[0233] In this example, transformer 400 includes an auxiliary winding Aux.

[0234] exist Figure 8H In this circuit, Q3 (additional switch 800) is placed outside the primary-side controller 300. Zero-voltage switching (ZVS) in state 2 is achieved by using Q3 to transfer Caux energy from the Aux winding of transformer 400 to the primary-side winding in state A. The energy source stored in Caux can vary, originating from sources such as controller Vcc, input voltage (Vin), output voltage (Vo), or, as shown here, from the Aux winding itself in state 1.

[0235] Figure 8I This is a schematic diagram of a power converter 302 according to the eighteenth embodiment of the present disclosure, which can be used with any of the controller 300 embodiments described herein, as understood by those skilled in the art.

[0236] exist Figure 8I In this circuit, Q3 (additional switch 800) is integrated into the primary-side controller 300. Zero-voltage switching (ZVS) in state 2 is achieved by using Q3 to transfer Caux energy from the Aux winding of transformer 400 to the primary-side winding in state A. The energy source stored in Caux can vary, originating from sources such as controller Vcc, input voltage (Vin), output voltage (Vo), or, as shown here, from the Aux winding itself in state 1.

[0237] Figure 8H and Figure 8I This is an example demonstrating zero-voltage switching (ZVS) in state 2 by transferring Caux energy from the Aux winding of the transformer to the primary winding using Q3 in state A. The energy source stored in Caux can vary, originating from sources such as the controller Vcc, input voltage (Vin), output voltage (Vo), or... Figure 8G and Figure 8H As shown, this originates from the Aux winding itself in state 1.

[0238] Figure 8J This is a schematic diagram of a power converter 302 according to the nineteenth embodiment of the present disclosure, which can be used with any of the controller 300 embodiments described herein, as understood by those skilled in the art.

[0239] exist Figure 8J In this configuration, the auxiliary switch 800 is located on the secondary side of the transformer. The Q3 gate driver is integrated within the control module 806 of the controller 300. Zero-voltage switching (ZVS) in state 2 is achieved by discharging Co through Q3 in state A, thereby transferring the energy of Co from the secondary winding to the primary winding of the transformer in state A.

[0240] Figure 8J An alternative method is shown, in which ZVS in state 2 is achieved by discharging Co through Q3 in state A, transferring the energy of Co from the secondary winding to the primary winding of the transformer in state A. Other implementation circuits may exist, but the expected electrical behavior is to use an additional switch 800 in state A to assist the primary-side switch 310 in achieving zero-voltage switching (ZVS) in state 2. For example, although the additional switch 800 is shown as an N-type switch in these figures, depending on the application, the additional switch 800 may be implemented as an N-type or P-type switch.

[0241] Figures 8F-8J Some examples are provided of implementing additional switch 800 in state A to facilitate ZVS in state 2.

[0242] The embodiments disclosed herein can be combined to create other embodiments. Modifications described for one embodiment may be applied to other embodiments as understood by those skilled in the art.

[0243] It should be understood that the direct electrical connections (electrical connections without intermediate components) of the embodiments disclosed herein can be replaced by indirect connections involving additional components, as understood by those skilled in the art, provided that the basic functions of transmitting signals, data, or control remain intact.

[0244] Embodiments of this disclosure provide a controller using a novel operating sequence that enables a forward resonant half-bridge converter to: - Maintains high efficiency within the general input range (85-264VAC).

[0245] - Supports a wide range of output voltages and power for various applications.

[0246] - Ensure optimal performance from no-load to full-load conditions.

[0247] Embodiments of this disclosure address these challenges by introducing an improved operating sequence for the two primary-side switches (and an optional third switch), which enhances ZVS operation and adaptability to a variety of operating conditions.

[0248] This disclosure introduces a novel three-state control method for a forward resonant half-bridge converter. This innovation achieves zero-voltage switching (ZVS) of the two primary-side switches, resets the transformer windings, and improves efficiency over a wide input and output voltage range as well as across the entire load range.

[0249] The disclosed three-state control method for forward resonant half-bridge converters is designed for fast charging / power supply in consumer electronics, addressing the ever-increasing power demands of modern devices. As smartphones, tablets, laptops, and wearable electronics integrate more powerful processors, larger displays, and multiple sensors (e.g., cameras, biometric sensors), the need for higher power delivery becomes crucial.

[0250] Various improvements and modifications may be made to the above content without departing from the scope of this disclosure.

[0251] This disclosure provides the following terms: Clause 1. A controller for a power converter, the power converter being used to receive an input voltage on the primary side and generate an output voltage on the secondary side, the power converter comprising: A first primary-side switch is configured to switch between an on state and an off state; A second primary-side switch, configured to switch between an on state and an off state; and An energy transfer element configured to transfer energy from an input voltage to the secondary side; wherein: The controller is configured as follows: Operating in the first control state, wherein the controller is configured to: i) Switch the first primary side switch to the ON state for a first ON duration; and ii) After the first on-time, switch each of the first primary-side switch and the second primary-side switch to the off state for the first off-time; and Operating in the second control state, wherein the controller is configured to: i) Switch the second primary-side switch to the ON state for the second ON duration; and ii) After the second on-time, switch each of the first primary-side switch and the second primary-side switch to the off state for the second off-time.

[0252] Clause 2. The controller as described in Clause 1 is configured to: When operating in auxiliary control mode, the controller is configured as follows: i) Switch the first primary-side switch to the ON state for the duration of auxiliary ON; and ii) After the auxiliary on-time, switch each of the first primary-side switch and the second primary-side switch to the off state for the auxiliary off-time; or i) Switch the auxiliary switch to the ON state for the duration of auxiliary ON; and ii) After the auxiliary on duration, switch each of the first primary side switch, the second primary side switch and the auxiliary switch to the off state for the auxiliary off duration.

[0253] Clause 3. The controller as described in Clause 2, wherein: When operating in the first control state, the controller is configured to: After the first on-time, each of the first primary-side switch, the second primary-side switch, and the auxiliary switch is switched to the off state for the first off-time; and When operating in the second control state, the controller is configured to: After the second on-time, each of the first primary-side switch, the second primary-side switch, and the auxiliary switch is switched to the off state for the second off-time.

[0254] Clause 4. The controller as described in Clause 2 is configured to: The first control sequence is applied by repeating the loop between the following items: i) Operation in the first control state; ii) Operation in auxiliary control mode; and iii) Operate under the second control state.

[0255] Clause 5. The controller as described in Clause 4 is configured to, when applying the first control sequence: i) Switching from operation in the first control state to operation in the auxiliary control state; ii) Switching from operation in auxiliary control mode to operation in second control mode; and iii) Switching from operating in the second control state to operating in the first control state.

[0256] Clause 6. The controller as described in Clause 5 is configured to, when applying the first control sequence: i) After the first disconnection duration has elapsed, switch from operating in the first control state to operating in the auxiliary control state; ii) After the auxiliary disconnection duration has elapsed, switch from operating in the auxiliary control state to operating in the second control state; and iii) After the second disconnection duration has elapsed, switch from operating in the second control state to operating in the first control state.

[0257] Clause 7. The controller described in Clause 4 is configured to: The second control sequence is applied by repeating the cycle between the following items: i) Operation in the first control state; and ii) Operation in the second control state; and / or The third control sequence is applied by repeating the cycle between the following items: i) Operation in the first control state; ii) Operation in auxiliary control mode; and iii) Repeatedly operating in the second control state for multiple second control state switching cycles; and / or The fourth control sequence is applied by repeating the cycle between the following items: i) Operation in the first control state; ii) Repeatedly operating in the auxiliary control state for multiple auxiliary control state switching cycles; and iii) Operation under the second control state; wherein: The controller is configured to switch between applying a first control sequence and applying one or more of a second, third, and fourth control sequence.

[0258] Clause 8. The controller as described in Clause 7 is configured to: When applying the second control sequence: i) Switching from operation in the first control state to operation in the second control state; and ii) Switching from operation in the second control state to operation in the first control state; and / or When applying the third control sequence: i) Switching from operation in the first control state to operation in the auxiliary control state; ii) Switching from operation in auxiliary control mode to operation in second control mode; and iii) Switching from repeatedly operating in the second control state to operating in the first control state; and / or When applying the fourth control sequence: i) Switching from operation in the first control state to operation in the auxiliary control state; ii) Switching from repetitive operation in the auxiliary control state to operation in the second control state; and iii) Switching from operation in the second control state to operation in the first control state.

[0259] Clause 9. The controller as described in Clause 8 is configured to: When applying the second control sequence: i) After the first disconnection duration has elapsed, the operation changes from the first control state to the second control state; and ii) After the second disconnection duration has elapsed, switch from operating in the second control state to operating in the first control state; and / or When applying the third control sequence: i) After the first disconnection duration has elapsed, switch from operating in the first control state to operating in the auxiliary control state; ii) After the auxiliary disconnection duration has elapsed, switch from operating in the auxiliary control state to operating in the second control state; and iii) After the second disconnection duration of the last of a plurality of second control state switching cycles has elapsed, the operation transitions from repeatedly operating in the second control state to operating in the first control state; and / or When applying the fourth control sequence: i) After the first disconnection duration has elapsed, switch from operating in the first control state to operating in the auxiliary control state; ii) After the duration of the last auxiliary disconnection in a series of auxiliary control state switching cycles has elapsed, the operation transitions from repeatedly operating in the auxiliary control state to operating in the second control state; and iii) After the second disconnection duration has elapsed, switch from operating in the second control state to operating in the first control state.

[0260] Clause 10. The controller as described in Clause 4 is configured to: When the power converter is operating in discontinuous conduction mode (DCM), apply the first control sequence; and / or The second control sequence is applied when the power converter is operating in continuous conduction mode (CCM) or critical conduction mode (CRM).

[0261] Clause 11. The controller as described in Clause 1, wherein: The first primary-side switch and the second primary-side switch are coupled at the first node; and The energy transfer element is coupled to the first node.

[0262] Clause 12. The controller according to Clause 11 includes a first switch gate driver and a second switch gate driver, the first switch gate driver being configured to provide a first gate drive signal to drive a switching operation of a first primary-side switch, and the second switch gate driver being configured to provide a second gate drive signal to drive a switching operation of a second primary-side switch.

[0263] Clause 13. The controller as described in Clause 12 includes a control core, the control core being configured to: A first control signal is provided to a first switch gate driver, wherein a first gate drive signal depends on the first control signal; and A second control signal is provided to the second switch gate driver, and the second gate drive signal depends on the second control signal.

[0264] Clause 14. The controller according to Clause 13, wherein the control core is configured to sense one or more parameters of the power converter and adjust a first control signal and / or a second control signal based on the sensed one or more parameters.

[0265] Clause 15. The controller as described in Clause 14, wherein one or more parameters include: Input voltage; Output voltage; and The node voltage at the first node.

[0266] Clause 16. The controller as described in Clause 14 is configured to: When operating in auxiliary control mode, the controller is configured as follows: i) Switch the first primary-side switch to the ON state for the duration of auxiliary ON; and ii) After the auxiliary on duration, switch each of the first primary side switch and the second primary side switch to the off state for the auxiliary off duration; The first control sequence is applied by repeating the loop between the following items: i) Operation in the first control state; ii) Operation in auxiliary control mode; and iii) Operate under the second control state.

[0267] Clause 17. The controller as described in Clause 16 is configured to: The first control sequence is applied by operating in the initial state before repeating a cycle between operating in the first control state, operating in the auxiliary control state, and operating in the second control state; wherein: The initial state is one of the first control state, the auxiliary control state, and the second control state, and depends on one or more parameters sensed by the control core.

[0268] Clause 18. The controller as described in Clause 16, wherein: One of the parameters is the node voltage at the first node; and When the first control sequence is applied, the controller is configured to: i) When the node voltage exceeds the maximum threshold, the operation switches from the auxiliary control state to the second control state; and / or ii) When the node voltage drops below the minimum threshold, switch from operating in the second control state to operating in the first control state.

[0269] Clause 19. The controller as described in Clause 16 is configured to set one or more of the following based on one or more parameters sensed by the control core: First connection duration; First disconnection duration; Second connection duration; Second disconnection duration; Auxiliary connection duration; and Duration of auxiliary disconnection.

[0270] Clause 20. The controller as described in Clause 11, wherein: The energy transfer element includes a transformer comprising a primary winding and a secondary winding, the primary winding being coupled to a first node; and The power converter includes a resonant tank, which includes one or more resonant tank capacitors.

[0271] Clause 21. The controller according to Clause 1, wherein the power converter is a forward resonant half-bridge converter.

[0272] Clause 22. A power converter system comprising: A power converter for receiving an input voltage on the primary side and generating an output voltage on the secondary side, the power converter comprising: A first primary-side switch is configured to switch between an on state and an off state; A second primary-side switch, configured to switch between an on and off state; and Energy transfer elements, configured to transfer energy from the input voltage to the secondary side; and The controller is configured to: Operating in the first control state, wherein the controller is configured to: i) Switch the first primary side switch to the ON state for a first ON duration; and ii) After the first on-time, switch each of the first primary-side switch and the second primary-side switch to the off state for the first off-time; and Operating in the second control state, wherein the controller is configured to: i) Switch the second primary-side switch to the ON state for the second ON duration; and ii) After the second on-time, switch each of the first primary-side switch and the second primary-side switch to the off state for the second off-time.

[0273] Clause 23. A method for controlling a power converter, the power converter being used to receive an input voltage on the primary side and generate an output voltage on the secondary side, the power converter comprising: A first primary side switch is configured to switch between an on state and an off state; A second primary-side switch, configured to switch between an on and off state; and An energy transfer element is configured to transfer energy from the input voltage to the secondary side; The method includes: The controller is operated in the first control state using the following steps: i) Switch the first primary side switch to the ON state for a first ON duration; and ii) After the first on-time, switch each of the first primary-side switch and the second primary-side switch to the off state for the first off-time; and The controller is operated in the second control state through the following steps: i) Switch the second primary-side switch to the ON state for the second ON duration; and ii) After the second on-time, switch each of the first primary-side switch and the second primary-side switch to the off state for the second off-time.

Claims

1. A controller for a power converter, the power converter being configured to receive an input voltage on a primary side and generate an output voltage on a secondary side, the power converter comprising: A first primary-side switch is configured to switch between an on state and an off state. A second primary-side switch is configured to switch between the on state and the off state; and An energy transfer element, configured to transfer energy from the input voltage to the secondary side; wherein: The controller is configured to: Operating in a first control state, wherein the controller is configured to: i) Switching the first primary-side switch to the on state for a first on duration; and ii) After the first on-time, switch each of the first primary-side switch and the second primary-side switch to the off-state for the first off-time; and Operating in a second control state, wherein the controller is configured to: i) Switching the second primary-side switch to the on state for a second on duration; and ii) After the second on-time, switch each of the first primary-side switch and the second primary-side switch to the off-state for the second off-time.

2. The controller according to claim 1, configured to: When operating in auxiliary control mode, the controller is configured to: i) Switch the first primary-side switch to the on state for the auxiliary on duration; and ii) After the auxiliary on duration, switch each of the first primary side switch and the second primary side switch to the off state for the auxiliary off duration; or i) Switch the auxiliary switch to the ON state for the duration of the auxiliary ON; and ii) After the auxiliary on duration, switch each of the first primary side switch, the second primary side switch and the additional switch to the off state for the auxiliary off duration.

3. The controller according to claim 2, wherein: When operating in the first control state, the controller is configured to: After the first on-time, each of the first primary-side switch, the second primary-side switch, and the additional switch is switched to the off-state for the first off-time. and When operating in the second control state, the controller is configured to: After the second on-time, each of the first primary-side switch, the second primary-side switch, and the additional switch is switched to the off-state for the second off-time.

4. The controller according to claim 2, configured to: The first control sequence is applied by repeating the loop between the following items: i) Operate under the first control state; ii) Operation under the auxiliary control state; and iii) Operate in the second control state.

5. The controller of claim 4, configured to, when the first control sequence is applied: i) Switching from operating in the first control state to operating in the auxiliary control state; ii) Switching from operation in the auxiliary control state to operation in the second control state; and iii) Switching from operating in the second control state to operating in the first control state.

6. The controller of claim 5, configured to, when the first control sequence is applied: i) After the first disconnection duration has elapsed, switch from operating in the first control state to operating in the auxiliary control state; ii) After the duration of the auxiliary disconnection has elapsed, switch from operating in the auxiliary control state to operating in the second control state; and iii) After the second disconnection duration has elapsed, switch from operating in the second control state to operating in the first control state.

7. The controller according to claim 4, configured to: The second control sequence is applied by repeating the cycle between the following items: i) Operating under the first control state; and ii) Operating in the second control state; and / or The third control sequence is applied by repeating the cycle between the following items: i) Operate under the first control state; ii) Operate under the auxiliary control state; and iii) Repeatedly operating in the second control state for multiple second control state switching cycles; and / or The fourth control sequence is applied by repeating the cycle between the following items: i) Operate under the first control state; ii) Repeatedly operate in the auxiliary control state for multiple auxiliary control state switching cycles; and iii) Operate in the second control state; wherein: The controller is configured to switch between applying the first control sequence and applying one or more of the second, third, and fourth control sequences.

8. The controller according to claim 1, wherein: The first primary-side switch and the second primary-side switch are coupled at the first node; The energy transfer element is coupled to the first node; and The controller includes a first gate driver and a second gate driver. The first gate driver is used to provide a first gate drive signal to drive the switching operation of the first primary-side switch, and the second gate driver is used to provide a second gate drive signal to drive the switching operation of the second primary-side switch.

9. The controller according to claim 8, comprising a control core, the control core being configured to: A first control signal is provided to the first switch gate driver, wherein the first gate drive signal depends on the first control signal; and A second control signal is provided to the second switch gate driver, and the second gate drive signal depends on the second control signal.

10. The controller according to claim 9, wherein, The control core is configured to sense one or more parameters of the power converter and adjust the first control signal and / or the second control signal based on the sensed one or more parameters.

11. The controller of claim 10, configured to: When operating in auxiliary control mode, the controller is configured to: i) Switch the first primary-side switch to the on state for the auxiliary on duration; and ii) After the auxiliary on duration, switch each of the first primary side switch and the second primary side switch to the off state for the auxiliary off duration; The first control sequence is applied by repeating the loop between the following items: i) Operate under the first control state; ii) Operation under the auxiliary control state; and iii) Operate in the second control state.

12. The controller according to claim 11, configured to: The first control sequence is applied by operating in the initial state before repeating a cycle between operating in the first control state, operating in the auxiliary control state, and operating in the second control state; wherein: The initial state is one of the first control state, the auxiliary control state, and the second control state, and depends on one or more parameters sensed by the control core.

13. A power converter system, comprising: A power converter, wherein the power converter receives an input voltage on the primary side and generates an output voltage on the secondary side, the power converter comprising: A first primary-side switch is configured to switch between an on state and an off state. A second primary-side switch, configured to switch between the on state and the off state; and An energy transfer element, configured to transfer energy from the input voltage to the secondary side; and The controller is configured to: Operating in a first control state, wherein the controller is configured to: i) Switching the first primary-side switch to the on state for a first on duration; and ii) After the first on-time, switch each of the first primary-side switch and the second primary-side switch to the off-state for the first off-time; and Operating in a second control state, wherein the controller is configured to: i) Switching the second primary-side switch to the on state for a second on duration; and ii) After the second on-time, switch each of the first primary-side switch and the second primary-side switch to the off-state for the second off-time.

14. A method for controlling a power converter, the power converter being configured to receive an input voltage on a primary side and generate an output voltage on a secondary side, the power converter comprising: A first primary-side switch is configured to switch between an on state and an off state. A second primary-side switch is configured to switch between the on state and the off state; and An energy transfer element configured to transfer energy from the input voltage to the secondary side; The method includes: The controller is operated in the first control state using the following steps: i) Switching the first primary-side switch to the on state for a first on duration; and ii) After the first on-time, switch each of the first primary-side switch and the second primary-side switch to the off-state for the first off-time; and The controller is operated in the second control state by the following operations: i) Switching the second primary-side switch to the on state for a second on duration; and ii) After the second on-time, switch each of the first primary-side switch and the second primary-side switch to the off-state for the second off-time.

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