Control module and adapter

Abstract

A control module and an adapter. The control module is used for determining the input current of a buck circuit and the output voltage of a loop compensation circuit, and on the basis of the relationship between the output voltage and the input current, controlling the turning off of a switch transistor of the buck circuit, wherein the turn-on duty cycle of the switch transistor is directly proportional to the quotient of the output voltage and an average value of the input current. In the present application, by configuring the turn-on duty cycle of a buck switch transistor to be directly proportional to the quotient of the output voltage of the loop compensation circuit and an average input current, power factor modulation can be realized, thereby eliminating the need for an input voltage sampling resistor and a corresponding multiplier.

Description

A control module and an adapter

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on August 30, 2023, with application number 202311116746.4 and application name “A Control Module and Adapter”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of electronic technology, and more specifically, to a control module and an adapter. Background Art

[0003] With the development of fast charging technology, the power required to charge terminal devices is increasing, reaching hundreds of watts. Due to standard restrictions on harmonics injected into the power grid, power supplies greater than 75W need to add a power factor correction (PFC) circuit to reduce the harmonics injected into the power grid by the device. To reduce peak current and thus conduction losses, high-power PFC circuits usually operate in continuous conduction mode (CCM); to reduce switching losses, small and medium-power PFCs usually operate in critical conduction mode (CRM).

[0004] The traditional control method for constant-frequency CCM buck PFC is average current control. Voltage divider resistors R1 and R2 are used to sample the input bus voltage and then multiply it by the output voltage of the voltage feedback loop to generate the current command Iref. The current command and the sampled input current voltage are then processed in the current feedback loop to produce a modulated waveform. This modulated waveform is then compared with a constant-frequency sawtooth waveform to generate the switch control signal. This control system requires a high-voltage resistor network to sample the bus voltage and a multiplier to multiply the instantaneous input voltage by the feedback circuit output to obtain the target average current.

[0005] However, the current control method requires adding multiple high-voltage resistors outside the control system to sample the bus voltage to achieve the tracking function, and adding a multiplier inside the control system to process the signal, resulting in a large system layout area and high standby power consumption.

[0006] Summary of the Invention

[0007] The present application provides a control module and an adapter that eliminate the need for an input voltage sampling resistor and a corresponding multiplier, thereby reducing the system layout area and standby power consumption.

[0008] In a first aspect, the present application provides a control module applicable to power supplies for devices such as terminal device adapters, base station power supplies, and server power supplies. The control module is configured to determine the input current of a buck circuit and the output voltage of a loop compensation circuit. The control module is further configured to control the switching of a buck circuit switch based on the relationship between the output voltage and the input current. The switching duty cycle of the switch is proportional to the quotient of the output voltage and the average value of the input current.

[0009] For example, the relationship between the output voltage and the output current can be understood as the relationship between the output voltage and the voltage of the capacitor after the capacitor is charged with the output current or a current proportional to the output current.

[0010] This application proposes a PFC control mode operating in constant-frequency CCM. In this mode, the on-duty cycle of the switching transistor is proportional to the quotient of the output voltage of the loop compensation circuit and the input average current, thereby achieving power factor modulation, thereby eliminating the input voltage sampling resistor and the corresponding multiplier.

[0011] In one possible implementation, the input current tracks the input voltage of the buck circuit.

[0012] In a possible implementation, the average value of the input current is an average value of the input current in each switching cycle.

[0013] In one possible implementation, the control module includes a current source and a capacitor; the current source is used to output a current proportional to the average value of the input current; the capacitor is used to charge according to the current output by the current source when the switch tube is turned on; the control module is specifically used to control the shutdown of the switch tube when the voltage of the capacitor reaches the output voltage.

[0014] In the above manner, a current proportional to the average input current is used to charge the capacitor, and the voltage of the capacitor (for example, the voltage is a sawtooth wave) is compared with the output voltage of the feedback circuit. When the voltage of the capacitor is greater than the output voltage of the feedback circuit, the PFC switch is turned off, thereby achieving the ratio calculation function without the need for a divider.

[0015] In a possible implementation, the control module is configured to control the switch tube to be turned on when the inductor current of the buck inductor passes through zero; or to control the switch tube to be turned on after a preset fixed time period according to a fixed-frequency pulse.

[0016] In a possible implementation, the Buck circuit further includes an auxiliary winding connected to the inductor; and the control module is configured to determine a zero-crossing point of the current of the inductor by detecting a voltage of the auxiliary winding.

[0017] In a possible implementation, the control module is configured to perform an OR operation on the fixed-frequency pulse and an inductor current zero-crossing signal of the buck inductor, and control the conduction of the switch tube according to the operation result.

[0018] In the above manner, the turn-on signal of the PFC switch tube is obtained by performing an OR operation on the fixed-frequency pulse and the zero-crossing signal of the PFC auxiliary winding, which can smoothly realize the switching between the CRM mode and the CCM mode.

[0019] In a possible implementation, the input current is the current of a sampling resistor of the buck circuit.

[0020] In a second aspect, the present application provides an adapter, comprising:

[0021] A power factor correction (PFC) circuit, comprising a rectifier bridge and a buck circuit;

[0022] And a control module as described in any one of the first aspects.

[0023] In a possible implementation, the PFC circuit further includes an auxiliary winding connected to the inductor.

[0024] In a third aspect, a control method is provided, comprising: determining the input current of the buck circuit and the output voltage of the loop compensation circuit; controlling the shutdown of the switch tube of the buck circuit based on the relationship between the output voltage and the input current; wherein the on-duty cycle of the switch tube is proportional to the quotient of the output voltage and the average value of the input current.

[0025] In one possible implementation, the input current tracks the input voltage of the buck circuit.

[0026] In a possible implementation, the average value of the input current is an average value of the input current in each switching cycle.

[0027] In one possible implementation, controlling the shutdown of the buck circuit's switch tube based on the relationship between the output voltage and the input current includes: outputting a current proportional to the average value of the input current through a current source; charging a capacitor according to the current output by the current source when the switch tube is turned on; and controlling the shutdown of the switch tube when the voltage of the capacitor reaches the output voltage.

[0028] In a possible implementation, the method further includes: controlling the switch tube to be turned on when the inductor current of the buck inductor passes through zero; or controlling the switch tube to be turned on after a preset fixed time period according to a fixed-frequency pulse.

[0029] In a possible implementation, the buck circuit further includes an auxiliary winding connected to the inductor; and the method further includes: determining a zero-crossing point of the current of the inductor by detecting the current of the auxiliary winding.

[0030] In a possible implementation, the method further includes: performing an OR operation on the fixed-frequency pulse and an inductor current zero-crossing signal of the buck inductor, and controlling the conduction of the switch tube according to the operation result.

[0031] In a possible implementation, the input current is the current of the sampling resistor of the buck. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1A is a schematic diagram of a PFC circuit;

[0033] FIG1B is a schematic diagram of a PFC circuit;

[0034] FIG2 is a waveform diagram of a PFC circuit operating under high voltage input and heavy load conditions;

[0035] Figure 3 is a diagram showing the PFC circuit operating at a low voltage input and heavy load;

[0036] FIG4 is a schematic diagram of a PFC circuit;

[0037] FIG5 is a flow chart of a control method provided in an embodiment of the present application;

[0038] FIG6 is a schematic diagram of a PFC circuit provided in an embodiment of the present application;

[0039] FIG7 is a schematic diagram of a PFC circuit provided in an embodiment of the present application;

[0040] Figure 8 shows the waveform under low input voltage and heavy load. DETAILED DESCRIPTION

[0041] The following describes the embodiments of the present invention in conjunction with the accompanying drawings. The terms used in the embodiments of the present invention are only used to explain the specific embodiments of the present invention, and are not intended to limit the present invention.

[0042] The embodiments of the present application are described below in conjunction with the accompanying drawings. Those skilled in the art will appreciate that, with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0043] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, and this is merely a way of distinguishing the objects of the same attributes when describing them in the embodiments of the present application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, system, product or equipment comprising a series of units need not be limited to those units, but may include other units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0044] As used herein, the terms "substantially," "about," and similar terms are used as terms of approximation, not as terms of degree, and are intended to take into account the inherent variations in measurements or calculations that one of ordinary skill in the art would recognize. Furthermore, the use of "may" when describing embodiments of the present invention refers to "one or more possible embodiments." As used herein, the terms "use," "using," and "used" may be considered synonymous with the terms "utilize," "utilizing," and "utilized," respectively. Additionally, the term "exemplary" is intended to refer to an example or illustration.

[0045] The following describes some concepts involved in this application:

[0046] (1) Adapter: refers to a device that has a voltage conversion function and supplies power to electronic equipment (also known as terminal equipment). It is also called a charger, switching power supply, charger, or power converter.

[0047] (2) Super Charger: refers to an adapter or charger that can charge a battery-powered device such as a mobile phone or computer quickly, shortening the charging time. It is also commonly called a Super Charger, rapid charger, fast charge, or quick charge.

[0048] (3) Half-bridge: It refers to an electrical topology structure in a switching power supply that uses two power switching tubes to work alternately to achieve power transmission. The main switching bridge is also called the main tube or the first switch; the auxiliary switching bridge is also called the radial tube or the second switch.

[0049] (4) Asymmetric half bridge: In the present invention, it means that the duty ratio of the upper bridge and the lower bridge is not 50% symmetrical.

[0050] (5) Controller IC: refers to the control unit of the product, which implements waveform detection and action logic.

[0051] (6) Transformer: A device in a switching power supply that is responsible for transmitting power and converting voltage.

[0052] (7) Auxiliary winding: The winding in the transformer that is not responsible for power transmission, such as the VCC winding.

[0053] (8) Primary winding: The winding placed on the primary side of the transformer responsible for input voltage and current.

[0054] (9) Secondary winding: The winding placed on the secondary side of the transformer responsible for output voltage and current.

[0055] FIG1A is a schematic diagram of a bridge buck power factor correction (Buck PFC) circuit.

[0056] As shown in Figure 1A, the bridge Buck PFC circuit consists of an uncontrolled rectifier and a Buck circuit. The input AC voltage Vin is rectified into a DC voltage Vrec by the uncontrolled rectifier circuit. The Buck circuit reduces the fluctuating DC voltage Vrec to a stable output voltage Vo.

[0057] Figure 2 shows the waveforms of a bridged buck PFC circuit operating under high-voltage input and heavy load conditions. When the inductor current I L1 crosses zero, switch Q1 turns on, exciting the inductor and causing the inductor current I L1 to rise. When the inductor current reaches its peak, switch Q1 turns off, allowing the inductor current to continue flowing through diode D1, demagnetizing the inductor and causing the inductor current I L1 to decrease until it reaches zero again. This operating mode is called CRM mode.

[0058] 1B , which is a schematic diagram of a common ground Buck circuit, it should be understood that the embodiments of the present application do not limit the specific structure of the Buck circuit.

[0059] It should be understood that in the CRM mode, the switch tube is turned on only after the inductor current passes through zero, so that the switch tube is turned on at zero voltage, thereby reducing switching losses.

[0060] It should be noted that when the input voltage Vin is less than the output voltage Vo, the Buck circuit cannot transfer energy from the input to the output, and the load is supplied with energy by the output capacitor CB in Figure 1A. This period is shown as Td in Figure 2.

[0061] Figure 3 is a diagram of a bridge Buck PFC circuit operating at a low input voltage and heavy load.

[0062] It should be understood that when the input voltage Vin decreases and the load remains unchanged, maintaining output power requires an increase in input current. This also increases the time Td during which power cannot be transferred from input to output, further increasing the input peak current. However, this increase in peak current leads to a sharp increase in switching device conduction losses, inductor losses, and rectifier diode losses, resulting in a sharp drop in system efficiency. Specifically, when the PFC circuit operates in CRM mode, the input peak current increases dramatically as the input voltage decreases, and accordingly, the system efficiency also drops sharply.

[0063] Figure 4 is the internal signal block diagram of PFC in CCM mode.

[0064] The traditional control method for constant-frequency CCM buck PFC is average current control. Figure 4 shows the internal signal flow. The input bus voltage is sampled using voltage-divider resistors R1 and R2 and multiplied by the output voltage of the voltage feedback loop to generate the current command, Iref. The current command and the sampled input current voltage are calculated in the current feedback loop to produce a modulated waveform. This modulated waveform is then compared with a constant-frequency sawtooth waveform to generate the switch control signal. This control system requires a high-voltage resistor network to sample the bus voltage and a multiplier to multiply the instantaneous input voltage by the feedback circuit output to obtain the target average current.

[0065] However, the current control method requires adding multiple high-voltage resistors outside the control system to sample the bus voltage to achieve the tracking function, and adding a multiplier inside the control system to process the signal, resulting in a large system layout area and high standby power consumption.

[0066] FIG5 is a schematic diagram of a control method 100 provided in an embodiment of the present application, including:

[0067] S110 , determining the input current of the buck circuit and the output voltage of the loop compensation circuit.

[0068] In a possible implementation, referring to FIG. 6 , the buck circuit may be connected after the full-bridge circuit, and the input current of the buck circuit may represent the input current of the PFC circuit.

[0069] In one possible implementation, the input current of the buck circuit is a current proportional to the input current of the PFC circuit. That is, the input current can represent the input current of the PFC circuit. For example, the input current of the PFC circuit can be directly used as the input current, or a current that is not the input current of the PFC circuit but can represent the input current of the PFC circuit can be used as the input current.

[0070] In one possible implementation, the PFC circuit's switch is controlled to be turned off based on a relationship between the output voltage and the first current. The switch's on-duty cycle is proportional to the quotient of the output voltage and an average current of the input current. The input current is the current flowing through a sampling resistor in the buck circuit.

[0071] For example, referring to FIG. 6 , FIG. 6 is a schematic diagram of a PFC circuit. After the voltage of the sampling resistor Rcs is filtered, the input current Iin can be obtained.

[0072] In one possible implementation, the output voltage of the loop compensation circuit, that is, the output voltage of the voltage regulation control loop (ie, the inner loop), may be determined.

[0073] For example, referring to FIG. 6 , the loop compensation output voltage is Vcomp.

[0074] S120, controlling the shutdown of the switch tube of the buck circuit according to the relationship between the output voltage and the input current; wherein the on-duty cycle of the switch tube is proportional to the quotient of the output voltage and the average value of the input current.

[0075] The average value of the input current may be an average value of the input current in each switching cycle.

[0076] In one possible implementation, the control module may include a current source and a capacitor; the current source may output a current proportional to the average value of the input current; when the switch tube is turned on, the capacitor is charged according to the current output by the current source; when the voltage of the capacitor reaches the output voltage, the switch tube is controlled to be turned off.

[0077] When the switch is on, the current source charges the capacitor Cramp with a current value of K*Iin, where K is the coefficient. When the voltage across the capacitor Cramp reaches the loop compensation output voltage Vcomp, the switch turns off. The switch turns back on at the next fixed-frequency clock signal. At this point, the converter operates in fixed-frequency CCM mode.

[0078] In the above manner, a current proportional to the average input current is used to charge the capacitor, and the voltage of the capacitor (for example, the voltage is a sawtooth wave) is compared with the output voltage of the feedback circuit. When the voltage of the capacitor is greater than the output voltage of the feedback circuit, the PFC switch is turned off, thereby achieving the ratio calculation function without the need for a divider.

[0079] According to the switch-off logic, the following formula can be obtained, where Ton is the on-time of the switch:

[0080] The volt-second balance formula of the inductor of the Buck converter is as follows, where Tsw is the on-time of the switch tube:

[0081] V in T on =V out T sw ;

[0082] From the above two formulas, we can get:

[0083] In steady-state operation, Vcomp, Vout, and Tsw are all constant values. The capacitance value Cramp and the proportional coefficient K are also set in advance. It can be seen that: Vcomp*Cramp / Vout / Tsw / K is a constant value, then Iin and Vin change proportionally, realizing the input current tracking the input voltage, that is, realizing the power factor correction function.

[0084] This application proposes a PFC control mode operating in constant-frequency CCM. In this mode, the on-duty cycle of the PFC switch is proportional to the quotient of the output voltage of the voltage feedback circuit and the average input current, thereby achieving power factor modulation and eliminating the input voltage sampling resistor and corresponding multiplier.

[0085] As shown in Figure 7, which is a schematic diagram of a PFC supporting CRM mode, in this embodiment, the switch-off condition is consistent with the CCM mode described in the above embodiment, while the switch-on condition adds the auxiliary winding zero crossing.

[0086] Specifically, in one possible implementation, when the PFC circuit operates in CRM, the switch tube is controlled to be turned on when the inductor current of the PFC inductor passes through zero; or, when the PFC circuit operates in critical conduction mode (CCM), the switch tube is controlled to be turned on after a preset fixed time period according to a fixed-frequency pulse.

[0087] In a possible implementation, the buck circuit further includes an auxiliary winding connected to the inductor; and the zero-crossing point of the current of the inductor can be determined by detecting the voltage of the auxiliary winding.

[0088] In a possible implementation, an OR operation may be performed on the fixed-frequency pulse and the inductor current zero-crossing signal of the buck inductor, and the conduction of the switch tube may be controlled according to the operation result.

[0089] The turn-on signal of the PFC switch tube is obtained by performing an OR operation on the fixed-frequency pulse and the zero-crossing signal of the PFC auxiliary winding, which can smoothly realize the switching between CRM mode and CCM mode.

[0090] After the switch is turned off, the auxiliary winding voltage drops from positive to negative, and after a zero-crossing comparison by the comparator, a turn-on signal for the switch is generated. When the fixed-frequency clock signal is low, the inductor is demagnetized, the auxiliary winding crosses zero, and the switch is turned on. At this point, the switch turns on at the bottom of the valley, minimizing switching losses and operating in CRM mode. Before the inductor current drops to zero, the fixed-frequency clock signal reaches a high level, causing the switch to hard-switched on, operating in CCM mode. This shows that the control strategy proposed in this embodiment of the present application can operate in either CCM or CRM mode, offering a wide range of applications.

[0091] Figure 8 shows the waveforms of this embodiment under low input voltage and heavy load. When the peak current is low, the switch Q1 turns on after the peak current drops to zero, achieving ZVS turn-on, reducing switching losses and operating in CRM mode. When the peak current is high, the switch Q1 turns on before the peak current drops to zero, reducing the peak current and conduction losses, and operating in CCM mode.

[0092] It should also be noted that the device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed across multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. In addition, in the drawings of the device embodiments provided in this application, the connection relationship between the modules indicates that there is a communication connection between them, which can be specifically implemented as one or more communication buses or signal lines.

[0093] Through the description of the above embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software plus necessary general hardware, and of course can also be implemented by special hardware including application-specific integrated circuits, special CPUs, special memories, special components, etc. In general, all functions performed by computer programs can be easily implemented with corresponding hardware, and the specific hardware structures used to implement the same function can also be diverse, such as analog circuits, digital circuits or special circuits, etc. However, for the present application, software program implementation is a better implementation method in most cases. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a readable storage medium, such as a computer's floppy disk, USB flash drive, mobile hard disk, ROM, RAM, magnetic disk or optical disk, etc., and includes a number of instructions to enable a computer device (which can be a personal computer, training equipment, or network equipment, etc.) to execute the methods described in each embodiment of the present application.

[0094] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware, or any combination thereof. When implemented by software, all or part of the embodiments may be implemented in the form of a computer program product.

[0095] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website, a computer, a training device or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website, a computer, a training device or a data center. The computer-readable storage medium can be any available medium that a computer can store or a data storage device such as a training device, a data center, etc. that includes one or more available media integrations. The available medium can be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

Claims

1. A control module, characterized in that: The control module is used to determine the input current of the buck circuit and the output voltage of the loop compensation circuit; The control module is also used to control the shutdown of the switch tube of the buck circuit according to the relationship between the output voltage and the input current; wherein the on-duty cycle of the switch tube is proportional to the quotient of the output voltage and the average value of the input current.

2. The control module according to claim 1, characterized in that: The average value of the input current is an average value of the input current in each switching cycle.

3. The control module according to claim 1 or 2, characterized in that: The control module includes a current source and a capacitor; The current source is used to output a current proportional to the average value of the input current; The capacitor is used to charge according to the current output by the current source when the switch tube is turned on; The control module is specifically used to control the switch tube to be turned off when the voltage of the capacitor reaches the output voltage.

4. The control module according to any one of claims 1 to 3, characterized in that: The control module is used to control the switch tube to be turned on when the inductor current of the inductor of the buck circuit passes through zero; or, The switch tube is controlled to be turned on after a preset fixed time period according to the fixed frequency pulse.

5. The control module according to claim 4, characterized in that: The Buck circuit also includes an auxiliary winding connected to the inductor; the control module is used to determine the zero-crossing point of the current of the inductor by detecting the voltage of the auxiliary winding.

6. The control module according to any one of claims 1 to 5, characterized in that: The control module is used to perform an OR operation on the fixed-frequency pulse and the inductor current zero-crossing signal of the inductor of the buck circuit, and control the conduction of the switch tube according to the operation result.

7. The control module according to any one of claims 1 to 6, characterized in that: The input current is the current of the sampling resistor of the buck circuit.

8. An adapter, comprising: A power factor correction (PFC) circuit, wherein the PFC circuit comprises a rectifier bridge and a buck circuit; And the control module according to any one of claims 1 to 7.

9. The adapter according to claim 8, characterized in that: The buck circuit also includes an auxiliary winding connected to the inductor.

10. A control method, characterized in that: The method comprises: Determine the input current of the buck circuit and the output voltage of the loop compensation circuit; According to the relationship between the output voltage and the input current, the switch tube of the buck circuit is controlled to be turned off; wherein the on-duty ratio of the switch tube is proportional to the quotient of the output voltage and the average value of the input current.

11. The method according to claim 10, characterized in that The average value of the input current is an average value of the input current in each switching cycle.

12. The method according to claim 10 or 11, characterized in that: The controlling the switching off of the switch tube of the buck circuit according to the relationship between the output voltage and the input current includes: outputting a current proportional to the average value of the input current through a current source; When the switch tube is turned on, the capacitor is charged according to the current output by the current source; When the voltage of the capacitor reaches the output voltage, the switch tube is controlled to be turned off.

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