CN116368723A

CN116368723A - Method and apparatus for controlling power conversion circuit, storage medium and program product

Info

Publication number: CN116368723A
Application number: CN202180074246.1A
Authority: CN
Inventors: 代胜勇; 杨滚; 秦亚霄
Original assignee: Huawei Digital Power Technologies Co Ltd
Current assignee: Huawei Digital Power Technologies Co Ltd
Priority date: 2021-07-27
Filing date: 2021-07-27
Publication date: 2023-06-30
Also published as: WO2023004592A1

Abstract

The present disclosure relates to a method and apparatus, a storage medium, and a program product for controlling a power conversion circuit. The method for controlling the power conversion circuit includes: receiving a detection signal representing a rate of change of a rectifying device voltage across a rectifying device with respect to time, the rectifying device being connected to a secondary winding of a transformer in the power conversion circuit; determining a duration of the rectifying device voltage within the predetermined rate of change range based on the detection signal and the predetermined rate of change range; and generating an enable signal for turning on the rectifying device in response to the duration exceeding the time threshold. The scheme of the present disclosure can effectively prevent misleading of the synchronous rectification device, thereby avoiding damage of the power switch caused by misleading in the power conversion circuit.

Description

Method and apparatus for controlling power conversion circuit, storage medium and program product

Technical Field

The present disclosure relates generally to the field of power electronics, and more particularly to methods and apparatus for controlling a power conversion circuit, a storage medium, a program product, a corresponding power conversion circuit, and an electronic device.

Background

Current power adapters widely use power conversion circuits, such as flyback circuits, for obtaining the power required by various electronic devices. In power conversion circuits, such as flyback circuits, a rectifier diode is typically provided at the secondary winding of the transformer. When the power conversion circuit operates under low voltage and high current conditions, the conduction voltage drop of the rectifier diode is high and the loss is high. Such rectifying losses sometimes account for even more than 60% of the total power loss. In order to reduce the rectifying loss, a synchronous rectifying technology may be adopted, that is, a power switch tube (for example, a metal oxide semiconductor field effect transistor) with extremely low on-state resistance is used to replace a rectifying diode to complete the rectifying operation.

When synchronous rectification technology is used, accurate conduction of synchronous rectification tubes needs to be achieved. However, in some cases (e.g., current discontinuities), there may be oscillations in the voltage across the synchronous rectifier. Such oscillations can cause misleading of the synchronous rectifier tube, thereby causing the power switching devices on the primary side and the secondary side of the transformer to conduct simultaneously, which can lead to damage to the power switching devices and affect the safety of the power adapter.

Disclosure of Invention

In order to solve the above-described problems, embodiments of the present disclosure provide a new scheme of controlling a power conversion circuit.

In a first aspect of the present disclosure, there is provided a method for controlling a power conversion circuit, comprising: receiving a detection signal representing a rate of change of a rectifying device voltage across a rectifying device with respect to time, the rectifying device being connected to a secondary winding of a transformer in the power conversion circuit; determining a duration of the rectifying device voltage within the predetermined rate of change range based on the detection signal and the predetermined rate of change range; and generating an enable signal for turning on the rectifying device in response to the duration exceeding the time threshold.

In the scheme of the disclosure, whether the rectifying device voltage oscillates can be judged by detecting whether the rate of change of the rectifying device voltage is continuously stable within a certain range, so that erroneous conduction under the condition of oscillation of the rectifying device voltage is effectively avoided, and the judgment is not influenced by other factors such as output voltage fluctuation.

In one implementation of the first aspect, receiving the detection signal includes: the method includes receiving a detection signal from a sensing device connected in parallel with the rectifying device and comprising a resistive element and a capacitive element connected in series, and the detection signal comprises a signal of a voltage across the resistive element. When the rectifying device voltage is applied to the capacitive element, the current flowing through the capacitive element corresponds to the rate of change of the rectifying device voltage with respect to time, and therefore, by detecting the voltage of the resistive element connected in series with the capacitive element, the rate of change of the rectifying device voltage with respect to time can be directly obtained in a simple manner.

In one implementation of the first aspect, receiving the detection signal includes: a plurality of digital sampled voltages are received from an analog-to-digital converter in a sensing arrangement, the sensing arrangement being connected in parallel with the rectifying device, and the analog-to-digital converter being operable to sample the rectifying device voltage a plurality of times in succession in time to generate a plurality of digital sampled voltages, the plurality of digital sampled voltages being indicative of a rate of change of the rectifying device voltage with respect to time. In such an implementation, the detection signal may also be a plurality of digital sampled voltages in succession, which may also be indicative of the rate of change of the rectifying device voltage with respect to time.

In one implementation of the first aspect, determining, based on the detection signal and the predetermined range of rates of change, a duration for which the rectified device voltage is within the predetermined range of rates of change includes: determining a rate of change of the plurality of digital sampled voltages with respect to time based on the plurality of digital sampled voltages; and determining a duration based on the determined rate of change and the predetermined range of rates of change. In such an implementation, the rate of change of the rectifying device voltage with respect to time may be obtained entirely digitally and the required duration determined.

In one implementation of the first aspect, generating the enable signal for turning on the rectifying device in response to the duration exceeding the time threshold comprises: starting timing by a timer in response to the rectifying device voltage falling within a predetermined rate of change range; and generating an enable signal in response to the time value of the timer exceeding the time threshold. By means of the timer, a determination of the duration of the falling of the rectified device voltage into the predetermined rate of change range can be achieved in a simple and reliable manner.

In one implementation manner of the first aspect, the method further includes: resetting the timer in response to the rectifying device voltage being outside of the predetermined rate of change range; or in response to generating the enable signal, clears the timer. By the implementation mode, the error conduction during voltage oscillation can be effectively avoided, and the next conduction control is ready.

In a second aspect of the present disclosure, there is provided a control apparatus for controlling a power conversion circuit, comprising: a processor; and a memory coupled to the processor, the memory having instructions stored therein, which when executed by the processor, cause the apparatus to perform the method according to the first aspect.

In a third aspect of the present disclosure, there is provided a computer readable storage medium having stored thereon computer program code which, when executed, performs the method according to the first aspect.

In a third aspect of the present disclosure, there is provided a computer program product tangibly stored on a computer-readable medium and comprising computer-executable instructions that, when executed, cause an apparatus to perform the method according to the first aspect.

In a fourth aspect of the present disclosure, there is provided a power conversion circuit comprising: a transformer; a rectifying device connected to a secondary winding of the transformer; and a control device according to the first aspect for controlling the rectifying device.

In a fifth aspect of the present disclosure, there is provided an electronic device comprising: a power supply device; and a power conversion circuit according to the fourth aspect, powered by the power supply device.

It should be understood that what is described in this summary is not intended to limit the critical or essential features of the embodiments of the disclosure nor to limit the scope of the disclosure. Other features of the present disclosure will become apparent from the following description.

Drawings

The above and other features, advantages and aspects of embodiments of the present disclosure will become more apparent by reference to the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, wherein like or similar reference numerals denote like or similar elements, in which:

FIG. 1 illustrates a schematic block diagram of an electronic device in which some embodiments of the present disclosure may be implemented;

FIG. 2 shows a schematic diagram of a power conversion circuit according to an embodiment of the present disclosure;

FIG. 3 shows a schematic diagram of one implementation of the circuitry within dashed box A of FIG. 1;

FIG. 4 shows a schematic diagram of another implementation of the circuitry within dashed box A of FIG. 1;

FIG. 5 shows a waveform schematic of various signals and voltages in a power conversion circuit;

FIG. 6 shows a schematic flow chart diagram of a method for controlling a power conversion circuit according to an embodiment of the disclosure; and

FIG. 7 shows a schematic block diagram of an example device that may be used to implement embodiments of the present disclosure.

Detailed Description

Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While certain embodiments of the present disclosure have been shown in the accompanying drawings, it is to be understood that the present disclosure may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, but are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for illustration purposes only and are not intended to limit the scope of the present disclosure.

In describing embodiments of the present disclosure, the term "comprising" and its like should be taken to be open-ended, i.e., including, but not limited to. The term "based on" should be understood as "based at least in part on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first," "second," and the like, may refer to different or the same object. The term "and/or" means at least one of the two items associated therewith. For example, "a and/or B" means A, B, or a and B. Other explicit and implicit definitions are also possible below.

In the following description of the specific embodiments, some repetition is not described in detail, but it should be understood that the specific embodiments are referred to and may be combined with each other.

In power conversion circuits employing synchronous rectification techniques, it is often possible to determine when to turn on a synchronous rectification device by detecting the polarity and magnitude of the voltage across the synchronous rectification device. However, as previously described, in some cases, after the synchronous rectification device is turned off, oscillations in the voltage across the synchronous rectification device may occur. Therefore, when oscillation occurs, the conduction timing is determined only by judging the polarity and magnitude of the voltage across the synchronous rectification device, which may cause misleading of the synchronous rectification device and may damage the power switching device in the power conversion circuit.

In order to ensure that the synchronous rectification device is capable of accurate conduction, the present disclosure provides a new method for controlling a power conversion circuit. Additional conduction conditions are further provided in the present disclosure such that the synchronous rectification device also needs to satisfy the additional conduction conditions before being turned on. After the synchronous rectification device is turned off, by sensing the change rate of the voltage across the synchronous rectification device relative to time and determining the duration of the change rate within a predetermined range, it can be determined whether an unexpected oscillation or other condition that may cause erroneous conduction exists across the rectification device, so that the synchronous rectification device can be turned on only if the conduction condition is met.

Fig. 1 illustrates a schematic block diagram of an electronic device 1000 in which some embodiments of the present disclosure may be implemented. According to an embodiment of the present disclosure, the electronic device 100 includes a power conversion circuit 100 and a power supply apparatus 200. In addition, the electronic device 100 may also include a load 300 such as a smart phone, a notebook computer, or the like. It is to be understood that although the power conversion circuit 100 and the power supply apparatus 200 are shown as separate components from the load 300, it is not limited thereto, and for example, at least one of the power conversion circuit 100 and the power supply apparatus 200 may be formed as a part of the load 300 such as a notebook computer. As an example, the power supply apparatus 200 may convert alternating current power from an AC power source (such as a utility grid) into direct current power and input to the power conversion circuit 100. The power conversion circuit 100 may then convert the received dc power to the dc power required for operation of the load 300.

Fig. 2 shows a schematic diagram of a power conversion circuit 100 according to an embodiment of the present disclosure. In fig. 2, a power supply V representing the power supply device 200 and the load 300, respectively, is also schematically shown _in And a load R _L . As an example, the power conversion circuit 100 is an asymmetric half-bridge flyback circuit (asymmetrical half bridge flyback, AHBF). However, it is understood that the power conversion circuit 100 may also be other types of power conversion circuits capable of employing synchronous rectification techniques, such as active clamp flyback (active clamp flyback, ACF) circuits, active zero voltage switching (active zero voltage switch, AZVS) circuits, quasi-resonant flyback (quad-resonance flyback, QF) circuits, and the like.

According to some embodiments of the present disclosure, the power conversion circuit 100 may include a transformer 140 and a synchronous rectification device 110 connected to a secondary winding of the transformer 140. As an example, the power conversion circuit 100 may further include a main power switch Q connected to the primary winding of the transformer 140 _main And an auxiliary power switch Q ₂ In which the main power switch Q _main And transformer140 are connected in series, while the auxiliary power switch Q ₂ Connected in parallel with the primary winding of the transformer 140. In addition, the primary side of the transformer 140 may also include a bus capacitor C _B Resonance capacitor C _r And resonant inductance L _r Wherein the bus capacitance C _B With input power V _in Parallel connection, resonant capacitor C _r And resonant inductance L _r Connected in series with an auxiliary power switch Q ₂ Between the drain of the transformer 140 and the primary winding of the transformer. The secondary side of the transformer 140 may also include an output capacitance C ₀ Wherein the capacitance C is output ₀ And the load R _L Connected in parallel. In fig. 1, inductance L _m Representing the excitation inductance of the transformer and the resonant inductance L _r May be constituted by a transformer leakage inductance or may be constituted by another inductance. It is appreciated that in different circuit topologies, power conversion circuit 100 may omit portions of or add more electrical components and power switches as desired.

The basic operation of the power conversion circuit 100 will be briefly described below. When the main power switch Q _main When turned on, the input power of the power conversion circuit 100 is applied to the primary winding of the transformer, the current of the primary winding rises, the magnetic flux increases, and the inductive energy storage increases. Induced potential V across secondary winding of transformer _BF (i.e. the voltage between the upper terminal B and the lower terminal F of the secondary winding in the figure) is negative, the synchronous rectification device is in an off state, and the load R _L Is formed by capacitor C ₀ Providing. When the main power switch Q _main When the power conversion circuit 100 is turned off, the power supply to the transformer 140 is stopped, the magnetic flux of the secondary winding is reduced from the maximum value, and the induced potential V across the secondary winding _BF Is positive (reverse occurs). The synchronous rectification device 110 is turned on to turn on the synchronous rectification device 110. Thus, by the current flowing through the synchronous rectification device 110, the magnetic energy of the transformer inductance is converted into electric energy to be directed to the load R _L Supplying power and causing a capacitor C ₀ And (5) charging.

It can be seen that the synchronous rectification device 110 will be subjected to a negative voltage during the transformer inductance energy storage phase, and the synchronous rectification device 110 remains in an off state. In the transformer inductance energy release phase, the synchronous rectification device 110 bears the forward voltage, and the synchronous rectification device 110 is conducted. Accordingly, by detecting the polarity of the voltage across the synchronous rectification device 110 and determining whether the magnitude of the voltage exceeds a certain threshold, it is possible to determine when to turn on the synchronous rectification device 110. However, as previously described, after the synchronous rectification device turns off, there may be oscillations in the voltage across the synchronous rectification device. Therefore, if only the polarity and magnitude of the voltage across the synchronous rectification device 110 is taken as the conduction condition, erroneous conduction of the synchronous rectification device 110 may be caused.

According to some embodiments of the present disclosure, the power conversion circuit 100 further comprises a sensing device 120 and a control device 130. The control device 130 may provide an additional conduction condition for the synchronous rectification device 110 based on the detection signal to avoid erroneous conduction of the synchronous rectification device 110. As an example, the sensing means 120 is connected with the synchronous rectification device 110 to sense the electrical quantity of the synchronous rectification device 110, and the sensing means 120 is further coupled to the control means 130 to provide a detection signal to the control means 130 for processing. The operation of the control power conversion circuit 100 according to the embodiment of the present disclosure will be described in detail below with reference to fig. 2.

The control means 130 may receive a detection signal from the sensing means 120, the detection signal being indicative of the rate of change of the rectifying device voltage across the rectifying device 110 with respect to time, the rectifying device 110 being connected to the secondary winding of the transformer 140 in the power conversion circuit 100. As an example, the sensing device 120 may sense the voltage across the rectifying device 110 and obtain the rate of change of the rectifying device voltage with respect to time based on the voltage. It is understood that the sensing device 120 may comprise any suitable device capable of sensing a rate of change of voltage. FIG. 5 shows waveforms of various signals and voltages in the power conversion circuit 100, where V _SR Represents the voltage across rectifying device 110, and V _dec Representing the cross-rectifying device 110Rate of change of voltage with respect to time. It can be seen that V _dec Substantially corresponds to V _SR Slope of the curve.

Fig. 3 shows a schematic diagram of one implementation of the circuitry within the dashed box a of fig. 2. In the implementation shown in fig. 3, the circuitry within dashed box a includes rectifying device 110 and sensing device 120-1. As an example, the rectifying device 110 may include a power switch tube, a freewheeling diode, and a parallel capacitor. In some embodiments, the freewheeling diode and the parallel capacitance may be a body diode and a parasitic capacitance of the power switch tube. In other embodiments, the freewheeling diode and the parallel capacitance may be separately added diodes and capacitances. Alternatively, the freewheeling diode and the shunt capacitance may also be removed in some cases. In some embodiments of the present disclosure, the control device 130 receives the detection signal from the sensing device 120-1, the sensing device 120-1 being connected in parallel with the rectifying device 110. In one embodiment, sensing device 120-1 includes a resistive cell 121 and a capacitive cell 122 connected in series, and the detection signal includes a voltage signal across resistive cell 121. As an example, the resistive unit 121 and the capacitive unit 122 connected in series are connected across the rectifying device 110, and thus the rate of change of the rectifying device voltage with respect to time can be directly sensed. Specifically, when the rectifying device voltage is applied across the capacitive cell 122, the current passing across the capacitive cell 122 substantially corresponds to the rate of change of the rectifying device voltage with respect to time as the capacitive cell 122 charges and discharges. Therefore, by detecting the voltage of the resistive element 121 connected in series with the capacitor device 122 by the detection circuit or detector 123, the rate of change of the rectifying device voltage with respect to time can be obtained. In one embodiment, the resistive element 121 and the capacitive element 122 may be a resistor and a capacitor, respectively. However, the resistive unit and the capacitive unit are not limited to the resistor and the capacitor, but may be any element having a resistive characteristic and a capacitive characteristic. For example, the resistive element may be a MOSFET tube or diode, and the capacitive element may be a suitable component that appears capacitive. Alternatively, the resistive element may be composed of a plurality of elements of resistive characteristics in series and/or parallel, and the capacitive element may be composed of a plurality of elements of capacitive characteristics in series and/or parallel. Alternatively, the resistive unit may also be a resistive network that is made up of a plurality of electrical elements and that exhibits resistance as a whole, and the capacitive unit may be a capacitive network that is made up of a plurality of electrical elements and that exhibits capacitance as a whole.

Based on the detection signal and the predetermined rate of change range, the control device 130 may determine a duration for which the rectifying device voltage is within the predetermined rate of change range. As an example, the predetermined rate of change range may include predefined upper and lower thresholds Th1 and Th2. The upper threshold Th1 and the lower threshold Th2 may be defined as a pair of positive and negative values having an absolute value slightly greater than zero. Thus, a slope of the rectifying device voltage that is continuously within the predetermined range indicates that the rate of change of the voltage with respect to time is continuously close to zero. That is, the voltage of the rectifying device 110 tends to be stable, not in an oscillating state. Referring to FIG. 5, at V _dec In the associated waveform diagrams, upper and lower thresholds Th1 and Th2, represented by dashed lines above and below the transverse axis (corresponding to zero values), indicate exemplary predetermined rate of change ranges. It will be appreciated that the specific magnitudes of the upper and lower thresholds or the predetermined rate of change range may be determined based on specific operating conditions and actual needs. The control device 130 may compare the voltage change rate corresponding to the detection signal with predefined upper and lower thresholds to continuously determine whether the change rate of the rectifying device voltage is within a predetermined change rate range, thereby determining whether there is a large oscillation of the rectifying device voltage. For example, in the case of obtaining the detection signal from the resistive element of the sensing device 120-1 shown in fig. 3, since the detection signal directly corresponds to the voltage slope, it is possible to compare the detection signal with the upper and lower thresholds directly or through scaling, and determine whether the rate of change continuously falls within a predetermined range according to the comparison result.

Fig. 4 shows a schematic diagram of another implementation of the circuit within the dashed box a of fig. 2. In the implementation shown in fig. 4, the circuitry within dashed box a includes rectifying device 110 and sensing device 120-2, and sensing device 120-2 includes detection circuitry or detector 124 and analog-to-digital converter 125. In certain embodiments of the present disclosure, the control device 130 receives a plurality of digitally sampled voltages from the analog-to-digital converter 125 in the sensing device 120-2, the sensing device 120-2 is connected in parallel with the rectifying device 110, and the analog-to-digital converter 125 is configured to sample the voltage across the rectifying device 110 a plurality of times in succession in time to generate a plurality of digitally sampled voltages that are indicative of the rate of change of the rectifying device voltage across the rectifying device 110 with respect to time. As an example, in sensing arrangement 120-2, a detection circuit or detector 124 may detect the voltage across rectifying device 110 and provide to analog-to-digital converter 125 to convert an analog signal related to the voltage to a digital signal to obtain a plurality of digital sampled voltages that are successive in time, which may represent the rate of change of the rectifying device voltage with respect to time.

In some embodiments of the present disclosure, control device 130 may determine a rate of change of the plurality of digitally sampled voltages with respect to time based on the plurality of digitally sampled voltages, and control device 130 may determine a duration of time that the rectified device voltage is within the predetermined rate of change range based on the determined rate of change and the predetermined rate of change range. For example, in the case of obtaining the detection signal from the digital-to-analog converter 125 in the sensing device 120-2 shown in fig. 4, the control device 130 may calculate a plurality of digital sampling voltages obtained from the digital-to-analog converter 125 to obtain the rate of change of these sampling voltages with time. Thus, the rate of change of the rectifying device voltage with respect to time may be determined and the duration determined further based on the predetermined range of rates of change.

The control means 130 may determine whether the duration determined above exceeds a time threshold. As an example, the time threshold may be appropriately set according to actual needs.

In response to the determined duration exceeding the time threshold, the control means 130 may generate an enable signal for turning on the rectifying device 110. As an example, the determined duration exceeding the time threshold means that the rectifying device voltage remains stable for a sufficiently long time without oscillation occurring, so the control means 130 may generate an enable signal for turning on the rectifying device 110. The enable signal may cause the rectifying device 110 to be in a state that can trigger conduction. The enable signal will cause the rectifying device 110 to trigger on together with a drive signal for triggering the rectifying device to conduct. The drive signal for triggering the switching on of the rectifier device can likewise be generated, for example, by the control device 130 or by a separate control device. For example, the control device 130 or another separate control device determines that the transformer secondary winding of the power conversion circuit 100 has entered the de-energized stage and that the rectifying device 110 needs to be turned on based on the received detection signal, e.g., based on the polarity and magnitude of the voltage across the rectifying device 110. Thus, the control device 130 or another separate controller may issue the drive signal to ultimately trigger the switching on of the rectifying device 110.

In certain embodiments of the present disclosure, the control device 130 may include a timer, and in response to the rectifying device voltage falling within a predetermined rate of change range, the timing may be initiated by the timer. Thus, the time value of the timer may indicate the duration of the rectifying device voltage falling within the predetermined rate of change range. The time value of the timer exceeding the time threshold means that the duration of the rectifying device voltage falling within the predetermined rate of change range exceeds the time threshold. Accordingly, in response to the time value of the timer exceeding the time threshold, the control device 130 may generate an enable signal for turning on the rectifying device 110.

According to an embodiment of the present disclosure, the process of controlling the power conversion circuit 100 may further include: in response to the rectifying device voltage being outside of the predetermined rate of change range, the control means 130 clears the timer; or in response to generating the enable signal, the control device 130 clears the timer. As an example, the timer may be cleared once the rectifying device voltage leaves or is not within a predetermined rate of change range. Therefore, if the voltage of the rectifying device oscillates, the change rate of the voltage of the rectifying device repeatedly enters and leaves the range of the preset change rate in a short time, and the timer is cleared to zero so that the time threshold cannot be reached, and the situation that the voltage of the rectifying device is turned on by mistake when the voltage of the rectifying device oscillates can be avoided. Furthermore, once the control means 130 generates the enable signal, a timer may be cleared to be ready for the next on-control of the rectifying device.

Various signals and outputs of the power conversion circuit 100 in controlling the power conversion circuit 100 according to an embodiment of the present disclosure are described below with reference to fig. 5. In FIG. 5, a waveform diagram associated with Qmain gate represents the main power switch Q of the power conversion circuit 100 _main A waveform diagram associated with Q2gate represents the main power switch Q of the power conversion circuit 100 _main Gate signal waveform of (V) _dssw The associated waveform diagram represents V of the power conversion circuit 100 _dssw And V _SR The associated waveform diagram represents the voltage V across the rectifying device 110 of the power conversion circuit 100 _SR And V is as follows _dec The associated waveform diagram represents the voltage V _SR Waveform of the rate of change with respect to time.

The 6 moments t1 to t6 are exemplarily shown below the horizontal axis of time of fig. 5. At t1, the rectifying device 110 is turned off, the voltage V across the rectifying device 110 _SR Negative and its absolute value increases rapidly; at t2, voltage V across rectifying device 110 _SR Tend to stabilize and the voltage V _SR Rate of change V with respect to time _dec Entering a predetermined rate of change range; at t3, rate of change V _dec The duration of time of entering the predetermined rate of change range exceeds the time threshold t _hold This represents the voltage V _SR In a steady state, the control means 130 thus generates an active enable signal, i.e. the SR flag signal goes from low to high; during t4 to t5, the voltage V across the rectifying device 110 _SR Oscillation occurs, and the rate of change V _dec The duration in the predetermined rate of change range does not always exceed the time threshold t _hold The SR flag signal is therefore always low; at t5, voltage V across rectifying device 110 _SR Becomes a stable voltage and a change rate V _dec Entering a predetermined rate of change range; at t6, rate of change V _dec Enter a predetermined rate of change rangeThe duration of time exceeds the time threshold t _hold This represents the voltage V _SR The oscillation is ended and a steady state is entered, so the control device 130 generates an active enable signal, i.e. the SR flag signal goes from low to high.

It can be seen that the scheme of the embodiments of the present disclosure can be applied at voltage V _SR The oscillation prevents the output of an active enable signal, thereby disabling the rectifier device 110 from turning on. The scheme simply and effectively avoids the wrong conduction of the synchronous rectification device and is not influenced by other factors such as output voltage fluctuation.

The control means 130 in the power conversion circuit 100 may be implemented in a variety of ways. In certain embodiments of the present disclosure, the control apparatus 130 may be, for example, a control device including a processing unit. Alternatively, the control device 130 may be any other apparatus having calculation and control functions, for example, the control device 130 may be implemented in the form of an analog circuit, a digital circuit, or the like.

Fig. 6 shows a schematic flow chart of a method 600 for controlling a power conversion circuit according to an embodiment of the disclosure. The method 600 can be implemented in the power conversion circuit 100 and performed by the control device 130. Accordingly, the various aspects described above with respect to fig. 1-5 may be applicable to method 600.

At block 601, a detection signal is received that is representative of a rate of change of a rectifying device voltage across the rectifying device 110 with respect to time, the rectifying device being connected to a secondary winding of the transformer 140 in the power conversion circuit 100.

At block 602, a duration for which the rectifying device voltage is within a predetermined rate of change range is determined based on the detection signal and the predetermined rate of change range.

At block 603, it is determined whether the duration exceeds a time threshold.

At block 604, an enable signal to turn on the rectifying device 110 is generated in response to the duration exceeding the time threshold.

Fig. 7 shows a schematic block diagram of an example device 700 that may be used to implement embodiments of the present disclosure. The apparatus 700 may be used to implement the control device 130 of fig. 2. As shown in fig. 7, the device 700 includes a computing unit 701 that may perform various suitable actions and processes in accordance with computer program instructions stored in Random Access Memory (RAM) and/or Read Only Memory (ROM) 702 or loaded into RAM and/or ROM 702 from a storage unit 707. In RAM and/or ROM 702, various programs and data required for the operation of device 700 may also be stored. The computing unit 701 and the RAM and/or ROM 702 are connected to each other by a bus 703. An input/output (I/O) interface 704 is also connected to bus 703.

Various components in device 700 are connected to I/O interface 704, including: an input unit 705 such as a keyboard, a mouse, or the like; an output unit 706 such as various types of displays, speakers, and the like; a storage unit 707 such as a magnetic disk, an optical disk, or the like; and a communication unit 708, such as a network card, modem, wireless communication transceiver, or the like. The communication unit 708 allows the device 700 to exchange information/data with other devices via a computer network, such as the internet, and/or various telecommunications networks.

The computing unit 701 may be a variety of general and/or special purpose processing components having processing and computing capabilities. Some examples of computing unit 701 include, but are not limited to, a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), various specialized Artificial Intelligence (AI) computing chips, various computing units running machine learning model algorithms, a Digital Signal Processor (DSP), and any suitable processor, controller, microcontroller, etc. The computing unit 701 performs the various methods and processes described above, such as method 600. For example, in some embodiments, the method 600 may be implemented as a computer software program tangibly embodied on a machine-readable medium, such as the storage unit 707. In some embodiments, part or all of the computer program may be loaded and/or installed onto device 700 via RAM and/or ROM and/or communication unit 708. One or more of the steps of method 600 described above may be performed when a computer program is loaded into RAM and/or ROM and executed by computing unit 701. Alternatively, in other embodiments, the computing unit 701 may be configured to perform the method 600 by any other suitable means (e.g., by means of firmware).

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program code may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus such that the program code, when executed by the processor or controller, causes the functions/operations specified in the flowchart and/or block diagram to be implemented. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of this disclosure, a machine-readable medium may be a tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Moreover, although operations are depicted in a particular order, this should be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the present disclosure. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are example forms of implementing the claims.

Claims

A method for controlling a power conversion circuit, comprising:

receiving a detection signal representing a rate of change of a rectifying device voltage across a rectifying device with respect to time, the rectifying device being connected to a secondary winding of a transformer in the power conversion circuit;

determining a duration of time that the rectifying device voltage is within a predetermined rate of change range based on the detection signal and the predetermined rate of change range; and

an enable signal for turning on the rectifying device is generated in response to the duration exceeding a time threshold.
The method of claim 1, wherein receiving the detection signal comprises:

the detection signal is received from a sensing device connected in parallel with the rectifying device and comprising a resistive element and a capacitive element connected in series, and the detection signal comprises a signal of a voltage across the resistive element.
The method of claim 1, wherein receiving the detection signal comprises:

a plurality of digital sampled voltages are received from an analog-to-digital converter in a sensing arrangement, the sensing arrangement being connected in parallel with the rectifying device, and the analog-to-digital converter being operable to sample the rectifying device voltage a plurality of times in succession in time to generate the plurality of digital sampled voltages, the plurality of digital sampled voltages being indicative of a rate of change of the rectifying device voltage with respect to time.
The method of claim 3, wherein determining, based on the detection signal and the predetermined range of rates of change, a duration that the rectifying device voltage is within the predetermined range of rates of change comprises:

determining a rate of change of the plurality of digital sampled voltages with respect to time based on the plurality of digital sampled voltages; and

the duration is determined based on the determined rate of change and the predetermined range of rates of change.
The method of any of claims 1-4, wherein generating an enable signal for turning on the rectifying device in response to the duration exceeding a time threshold comprises:

starting to count by a timer in response to the rectifying device voltage falling within the predetermined rate of change range; and

the enable signal is generated in response to a time value of the timer exceeding the time threshold.
The method of claim 5, further comprising:

resetting the timer in response to the rectifying device voltage being outside the predetermined rate of change range; or (b)

In response to generating the enable signal, the timer is cleared.
A control apparatus for controlling a power conversion circuit, comprising:

a processor; and

a memory coupled with the processor, the memory having instructions stored therein, which when executed by the processor, cause the apparatus to perform the method of any of claims 1-6.
A computer readable storage medium having stored thereon computer program code which, when executed, performs the method of any of claims 1 to 6.
A computer program product tangibly stored on a computer-readable medium and comprising computer-executable instructions that, when executed, cause an apparatus to perform the method of any one of claims 1 to 6.
A power conversion circuit, comprising:

a transformer;

a rectifying device connected to a secondary winding of the transformer; and

the control apparatus according to claim 7, for controlling the rectifying device.
An electronic device, comprising:

a power supply device; and

the power conversion circuit of claim 10, powered by the power supply device.