Control module and adapter

Abstract

The invention discloses a control module and an adapter, and the control module is used for determining the input current of a buck circuit and the output voltage of a loop compensation circuit. According to the relationship between the output voltage and the input current, controlling the turn-off of a switching tube of the buck circuit; wherein the turn-on duty ratio of the switching tube is in direct proportion to the quotient of the output voltage and the average value of the input current. According to the invention, the turn-on duty ratio of the buck switch tube is proportional to the quotient of the output voltage and the input average current of the loop compensation circuit, and power factor modulation can be realized, so that an input voltage sampling resistor and a corresponding multiplier are omitted.

Description

Technical Field

[0001] The present application relates to the field of electronic technology, and more specifically, to a control module and an adapter. Background Art

[0002] With the development of fast charging technology, the power for charging terminal devices is getting larger and larger, reaching the order of hundreds of watts. Due to the standard restrictions on harmonic injection 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. In order to reduce the peak current and thus reduce the conduction loss, high-power PFC circuits usually operate in continuous conduction mode (CCM); in order to reduce switching losses, small and medium-power PFCs usually operate in critical conduction mode (CRM).

[0003] The traditional control method of Buck PFC in fixed-frequency CCM is the average current control method. After using the voltage divider resistors R1 and R2 to sample the input bus voltage, it is multiplied by the output voltage of the voltage feedback loop to obtain the current command Iref. The current command and the input current sampling voltage are calculated by the current feedback loop to obtain a modulated wave. The modulated wave is compared with the fixed-frequency sawtooth wave to generate a switch control signal. It can be seen that the control system requires a high-voltage resistor network to sample the bus voltage and add a multiplier to multiply the instantaneous input voltage with the output of the feedback circuit to obtain the target average current value.

[0004] 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. Summary of the invention

[0005] The present application provides a control module and an adapter, which eliminate the need for an input voltage sampling resistor and a corresponding multiplier, thereby reducing the system layout area and standby power consumption.

[0006] In the first aspect, the present application provides a control module that can be applied to power supplies for devices such as terminal device adapters, base station power supplies, and server power supplies. 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 switch of the buck circuit according to the relationship between the output voltage and the input current; wherein the on-duty cycle of the switch is proportional to the quotient of the output voltage and the average value of the input current.

[0007] 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 with a current proportional to the output current.

[0008] The present application proposes a control mode of PFC operating in constant frequency CCM. In this mode, the on-duty cycle of the switch tube is proportional to the quotient of the output voltage of the loop compensation circuit and the input average current, so that power factor modulation can be achieved, thereby eliminating the input voltage sampling resistor and the corresponding multiplier.

[0009] In one possible implementation, the input current tracks the input voltage of the buck circuit.

[0010] In a possible implementation, the average value of the input current is an average value of the input current in each switching cycle.

[0011] 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.

[0012] 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 tube is turned off, thereby realizing the ratio function without a divider.

[0013] In a possible implementation, the control module is used 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.

[0014] 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 a current of the inductor by detecting a voltage of the auxiliary winding.

[0015] In a possible implementation, the control module is used 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.

[0016] 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, so that the switching between the CRM mode and the CCM mode can be smoothly realized.

[0017] In a possible implementation, the input current is a current of a sampling resistor of the buck circuit.

[0018] In a second aspect, the present application provides an adapter, comprising:

[0019] A power factor correction (PFC) circuit, wherein the PFC circuit comprises a rectifier bridge and a buck circuit;

[0020] And a control module as described in any one of the first aspects.

[0021] In a possible implementation, the PFC circuit further includes an auxiliary winding connected to the inductor.

[0022] In a third aspect, a control method is provided, the method 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 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.

[0023] In one possible implementation, the input current tracks the input voltage of the buck circuit.

[0024] In a possible implementation, the average value of the input current is an average value of the input current in each switching cycle.

[0025] In a possible implementation, controlling the shutdown 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; 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] In a possible implementation, the input current is the current of the sampling resistor of the buck. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1A A schematic diagram of a PFC circuit;

[0031] Figure 1B A schematic diagram of a PFC circuit;

[0032] Figure 2 This is a waveform diagram of the PFC circuit working under high voltage input and heavy load conditions;

[0033] Figure 3 This is a diagram showing the PFC circuit working under low voltage input and heavy load.

[0034] Figure 4 A schematic diagram of a PFC circuit;

[0035] Figure 5 A schematic diagram of a control method provided in an embodiment of the present application;

[0036] Figure 6 A schematic diagram of a PFC circuit provided in an embodiment of the present application;

[0037] Figure 7 A schematic diagram of a PFC circuit provided in an embodiment of the present application;

[0038] Figure 8 The waveform diagram shows the waveform under low input voltage and heavy load. DETAILED DESCRIPTION

[0039] The embodiments of the present invention are described below in conjunction with the accompanying drawings in the embodiments of the present invention. The terms used in the implementation mode 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.

[0040] 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.

[0041] 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 need not be 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, which is only to describe the distinction mode adopted by the objects of the same attributes when describing 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.

[0042] As used herein, the terms "substantially," "about," and the like are used as terms of approximation, not as terms of degree, and are intended to take into account the inherent deviations of measurements or calculations that one of ordinary skill in the art would know. In addition, the use of "may" when describing embodiments of the present invention means "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. In addition, the term "exemplary" is intended to refer to an example or illustration.

[0043] Next, some concepts involved in this application are explained:

[0044] (1) Adapter: refers to a device that has a voltage conversion function and is used to power electronic equipment (also known as terminal equipment). It is also called a charger, a switching power supply, a charger, or a power converter.

[0045] (2) Super Charger: refers to an adapter or charger that can charge a battery-powered device such as a mobile phone or computer quickly and shorten the charging time. It is also commonly called a Super Charger, a rapid charger, a fast charge, or a quick charge.

[0046] (3) Half-bridge: refers to an electrical topology structure in which two power switching tubes work alternately to achieve power transmission in a switching power supply. 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.

[0047] (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.

[0048] (5) Controller IC: refers to the control unit of the product, which implements waveform detection and action logic.

[0049] (6) Transformer: A device in a switching power supply that is responsible for transmitting power and converting voltage.

[0050] (7) Auxiliary winding: The winding in the transformer that is not responsible for power transmission, such as the VCC winding.

[0051] (8) Primary winding: The winding placed on the primary side of the transformer responsible for input voltage and current.

[0052] (9) Secondary winding: The winding placed on the secondary side of the transformer responsible for output voltage and current.

[0053] Figure 1A The invention is a schematic diagram of a bridge buck power factor correction (Buck Power Factor Correction, Buck PFC) circuit.

[0054] like Figure 1A As shown, the bridge Buck PFC circuit is composed of an uncontrolled rectifier and a Buck circuit. The input AC voltage Vin is rectified into a DC voltage Vrec after passing through the uncontrolled rectifier circuit, and the Buck circuit reduces the fluctuating DC voltage Vrec to a stable output voltage Vo.

[0055] The waveform of the bridge Buck PFC circuit working under high voltage input and heavy load is as follows Figure 2 As shown in the figure, when the inductor current IL1 passes through zero, the switch tube Q1 is turned on, the inductor is excited, and the inductor current IL1 rises. When the inductor current reaches the peak current of IL1, the switch tube Q1 is turned off, the inductor current continues to flow through the diode D1, the inductor is demagnetized, and the inductor current IL1 decreases until the inductor current drops to 0 again. This working mode is called CRM mode.

[0056] In addition, refer to Figure 1B , Figure 1B It should be understood that the embodiment of the present application does not limit the specific structure of the buck circuit.

[0057] 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.

[0058] It should be noted that when the input voltage Vin < output voltage Vo, the Buck circuit cannot transfer energy from input to output, and the load is Figure 1AThe output capacitor CB in the circuit supplies energy. Figure 2 As shown in Td.

[0059] Figure 3 This is a bridge Buck PFC circuit working under low voltage input and heavy load waveform.

[0060] It should be understood that when the input voltage Vin in the circuit decreases and the load remains unchanged, if the output power needs to be maintained unchanged, the input current will inevitably increase; at the same time, the time Td during which power cannot be transferred from input to output will be correspondingly extended, which will also cause a further increase in the input peak current. However, the increase in peak current will lead to a sharp increase in the conduction loss of the switching device, the loss of the inductor and the loss of the rectifier diode, which will in turn lead to a sharp drop in system efficiency. That is, when the PFC circuit works in CRM mode, the input peak current will increase sharply as the input voltage decreases, and accordingly, the system efficiency will also decrease sharply.

[0061] Figure 4 It is the internal signal block diagram of PFC in CCM mode.

[0062] The traditional control method of Buck PFC in fixed frequency CCM is the average current control method. Its internal signal block diagram flow is as follows: Figure 4 As shown. After using the voltage divider resistors R1 and R2 to sample the input bus voltage, it is multiplied by the output voltage of the voltage feedback loop to obtain the current command Iref. The current command and the input current sampling voltage are calculated by the current feedback loop to obtain a modulated wave. The modulated wave is compared with the fixed-frequency sawtooth wave to generate a switch control signal. It can be seen that the control system requires a high-voltage resistor network to sample the bus voltage and add a multiplier to multiply the instantaneous input voltage with the output of the feedback circuit to obtain the target average current value.

[0063] 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.

[0064] Figure 5 1 is a schematic diagram of a control method 100 provided in an embodiment of the present application, comprising:

[0065] S110, determining the input current of the buck circuit and the output voltage of the loop compensation circuit.

[0066] In one possible implementation, refer to Figure 6 , the buck circuit can be connected after the full-bridge circuit, and the input current of the buck circuit can characterize the input current of the PFC circuit.

[0067] In a possible implementation, the input current of the buck circuit is a current that is proportional to the input current of the PFC circuit. That is, the input current can characterize 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 characterize the input current of the PFC circuit can be used as the input current.

[0068] In a possible implementation, the switch tube of the PFC circuit is turned off according to the relationship between the output voltage and the first current; wherein the on-duty ratio of the switch tube is proportional to the quotient of the output voltage and the average current of the input current. The input current is the current of the sampling resistor of the buck circuit.

[0069] For example, see Figure 6 , Figure 6 This 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.

[0070] In a 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.

[0071] For example, see Figure 6 , the loop compensation output voltage is Vcomp.

[0072] S120, controlling the switch of the buck circuit to turn off according to the relationship between the output voltage and the input current; wherein the on-duty cycle of the switch is proportional to the quotient of the output voltage and the average value of the input current.

[0073] The average value of the input current may be an average value of the input current in each switching cycle.

[0074] In a 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.

[0075] When the switch is turned on, the current source charges the capacitor Cramp, and its current value is K*Iin, where K is the coefficient. When the voltage across the capacitor Cramp reaches the loop compensation output voltage Vcomp, the switch is turned off. Wait until the next fixed-frequency clock signal, and the switch is turned on again. At this time, the converter works in the fixed-frequency CCM mode.

[0076] 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 tube is turned off, thereby realizing the ratio function without a divider.

[0077] According to the switch-off logic, the following formula can be obtained, where Ton is the switch-on time:

[0078]

[0079] 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:

[0080] V in T on =V out T sw ;

[0081] From the above two formulas, we can get:

[0082]

[0083] In steady-state operation, Vcomp, Vout and Tsw are all constant values, and 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 certain value, then Iin changes proportionally with Vin, realizing the input current tracking the input voltage, that is, realizing the power factor correction function.

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

[0085] like Figure 7 As shown, Figure 7 2 is a schematic diagram showing a PFC supporting the CRM mode. In this embodiment, the condition for turning off the switch tube can be consistent with the CCM mode described in the above embodiment, while the condition for turning on the switch tube adds the auxiliary winding zero crossing.

[0086] Specifically, in a 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 length 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 the CRM mode and the CCM mode.

[0090] After the switch tube is turned off, the auxiliary winding voltage will drop from positive voltage to negative voltage, and after the comparator crosses zero for comparison, a switch tube turn-on signal is generated. When the fixed-frequency clock signal is at a low level, the inductor demagnetization is completed, the auxiliary winding crosses zero, and the switch tube is turned on. At this time, the switch tube is turned on at the bottom of the valley to reduce switching losses and work in CRM mode; before the inductor current drops to 0, the fixed-frequency clock signal appears at a high level, the switch tube is hard-switched on, and works in CCM mode. It can be seen that the control strategy proposed in the embodiment of the present application can work in CCM or CRM mode, and has a wide range of adaptability.

[0091] like Figure 8 As shown in FIG. 1 , the waveform of this embodiment under low input voltage and heavy load. When the peak current is small, the switch tube Q1 will be turned on after the peak current drops to zero, realizing ZVS turn-on, reducing switching losses, and working in CRM mode; when the peak current is large, the switch tube Q1 will be turned on before the peak current drops to 0, reducing the peak current, thereby reducing conduction losses, and working in CCM mode.

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

[0093] Through the description of the above implementation mode, the technicians in the field can clearly understand that the present application can be implemented by means of software plus necessary general hardware, and of course, it can also be implemented by special hardware including special integrated circuits, special CPUs, special memories, special components, etc. In general, all functions completed by computer programs can be easily implemented by corresponding hardware, and the specific hardware structure used to implement the same function can also be various, such as analog circuits, digital circuits or special circuits. However, for the present application, software program implementation is a better implementation mode in more cases. Based on such an 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 floppy disk, a U disk, a mobile hard disk, a ROM, a RAM, a disk or an optical disk, etc., including a number of instructions to enable a computer device (which can be a personal computer, a training device, or a network device, 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 may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions may 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 may be transmitted from a website site, 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 site, computer, training device, or data center. The computer-readable storage medium may 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 may 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)), etc.

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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