Power circuits and electrical equipment

Abstract

This invention discloses a power supply circuit and an electrical device. The power supply circuit includes a detection circuit and a control circuit. The input terminal of the detection circuit is connected to AC power, and the output terminal of the detection circuit is connected to the control terminal of the control circuit. The output terminal of the control circuit is connected to the control system of the electrical device. The detection circuit outputs a power failure signal after detecting a first preset time of AC power failure. The control circuit modulates the voltage or the operating frequency based on the power failure signal, extending the holding time of the voltage transmitted to the control system to a second preset time. This power supply circuit can detect AC power failure using the detection circuit and extend the output holding time using the control circuit. Without adding an AC power failure signal line or an output capacitor, it solves the problem of short output holding time during AC power failure, thus meeting the requirements for power failure protection.

Description

Technical Field

[0001] This invention relates to the field of power supply technology. More specifically, it relates to a power supply circuit and electrical device. Background Technology

[0002] In electrical appliances such as televisions, washing machines, and refrigerators, the power supply typically has multiple power outputs. The two most important outputs are the control system power supply output and the power system power supply output. The control system power supply output has a lower power output, while the power system power supply output has a higher power output. With the increasing intelligence of various electrical appliances, the control system usually monitors the operating status of the appliances in real time, collects and stores large amounts of data, and uses this stored data for more intelligent control. Therefore, the control system of these appliances cannot tolerate sudden power outages during data storage and communication. This is to avoid data loss or even damage to the storage device caused by power failure. Thus, the control system needs to receive power failure information before a power outage occurs and take appropriate power failure protection actions.

[0003] In related technologies, power-down protection can be implemented by combining it with the main control board, but this usually requires a signal line from the power supply board containing the power circuit to the main control board for signal transmission. Alternatively, the electrolytic capacitors inside the power supply circuit can be used; when the output decreases, the energy stored in the output electrolytic capacitors is used to power electrical equipment. This requires a large-capacity electrolytic capacitor to power the equipment, ensuring the equipment has sufficient time to store data. However, if the capacitance of the electrolytic capacitor is too large, it cannot charge to the output voltage value in time when the power supply starts, making it impossible to establish feedback and ultimately causing the power supply to fail to start. Therefore, the capacitance of the electrolytic capacitor cannot be too large, resulting in only a short time for power output relying on the electrolytic capacitor, which is not conducive to meeting the requirements of power-down protection. Summary of the Invention

[0004] To address the problems described in the background section, some embodiments of the present invention provide a power supply circuit and electrical device that overcome the existing problems of needing to utilize signal lines and electrolytic capacitors, as well as the short output sustaining time. Without adding AC power-down signal lines or output capacitors, the output sustaining time is extended, which is beneficial for meeting power-down protection requirements.

[0005] This invention provides a power supply circuit, including: a detection circuit and a control circuit;

[0006] The input terminal of the detection circuit is connected to AC power, the output terminal of the detection circuit is connected to the control terminal of the control circuit, and the output terminal of the control circuit is connected to the control system of the electrical equipment.

[0007] The detection circuit is used to output a power failure signal after a first preset time period of AC power failure is detected;

[0008] The control circuit is used to perform voltage modulation or operating frequency modulation based on the power-down signal, so that the holding time of the voltage transmitted to the control system is extended to a second preset time.

[0009] The present invention also provides an electrical device, comprising:

[0010] Display screen;

[0011] A power system, electrically connected to the display screen, is used to drive the display screen to display images.

[0012] The control system is electrically connected to the power system;

[0013] In any of the above power supply circuits, the output terminal of the power supply circuit is connected to the control system, and the power supply circuit is used to supply power to the control system.

[0014] As can be seen from the above technical solutions, some embodiments of the present invention propose a power supply circuit, which includes a detection circuit and a control circuit. The input terminal of the detection circuit is connected to AC power, the output terminal of the detection circuit is connected to the control terminal of the control circuit, and the output terminal of the control circuit is connected to the control system of the electrical equipment. The detection circuit is used to output a power failure signal after detecting a first preset time of AC power failure. The control circuit is used to perform voltage modulation or operating frequency modulation based on the power failure signal, so that the holding time of the voltage transmitted to the control system is extended to a second preset time. This allows the power supply circuit to detect AC power failure using the detection circuit and extend the output holding time using the control circuit based on voltage modulation or operating frequency modulation. Without adding an AC power failure signal line or an output capacitor, the problem of short output holding time during AC power failure is solved, thus meeting the power failure protection requirements. Attached Figure Description

[0015] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly described below. Obviously, those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0016] Figure 1 This is a schematic diagram illustrating an application scenario of the present invention according to an exemplary embodiment;

[0017] Figure 2 This is a detailed structural diagram illustrating an application scenario according to an exemplary embodiment of the present invention;

[0018] Figure 3This is a waveform diagram illustrating a voltage transformation according to an exemplary embodiment of the present invention;

[0019] Figure 4 This is a schematic diagram of a power supply circuit according to an exemplary embodiment of the present invention;

[0020] Figure 5 This is a schematic diagram of another power supply circuit according to an exemplary embodiment of the present invention;

[0021] Figure 6 This is a schematic diagram of another power supply circuit according to an exemplary embodiment of the present invention;

[0022] Figure 7 This is a schematic diagram of a rectifier circuit according to an exemplary embodiment of the present invention;

[0023] Figure 8 This is a timing diagram illustrating an exemplary embodiment of the present invention;

[0024] Figure 9 This is a schematic diagram of a coupling sub-circuit according to an exemplary embodiment of the present invention;

[0025] Figure 10 This is a schematic diagram of another coupling sub-circuit according to an exemplary embodiment of the present invention;

[0026] Figure 11 This is a schematic diagram illustrating the structure of another coupling sub-circuit according to an exemplary embodiment of the present invention;

[0027] Figure 12 This is a schematic diagram illustrating the structure of another coupling sub-circuit according to an exemplary embodiment of the present invention;

[0028] Figure 13 This is a schematic diagram illustrating the structure of another coupling sub-circuit according to an exemplary embodiment of the present invention;

[0029] Figure 14 This is a schematic diagram illustrating the structure of another coupling sub-circuit according to an exemplary embodiment of the present invention;

[0030] Figure 15 This is a schematic diagram illustrating the structure of another coupling sub-circuit according to an exemplary embodiment of the present invention;

[0031] Figure 16 This is a schematic diagram of a detection sub-circuit according to an exemplary embodiment of the present invention;

[0032] Figure 17 This is a schematic diagram of another detection sub-circuit according to an exemplary embodiment of the present invention;

[0033] Figure 18 This is another timing diagram illustrating the present invention according to an exemplary embodiment;

[0034] Figure 19 This is a schematic diagram illustrating a gain curve according to an exemplary embodiment of the present invention;

[0035] Figure 20 This is a schematic diagram of another power supply circuit according to an exemplary embodiment of the present invention;

[0036] Figure 21 This is a schematic diagram of a control circuit according to an exemplary embodiment of the present invention;

[0037] Figure 22 This is a schematic diagram of another control circuit according to an exemplary embodiment of the present invention;

[0038] Figure 23 This is a schematic diagram illustrating the structure of another control circuit according to an exemplary embodiment of the present invention;

[0039] Figure 24 This is a schematic diagram illustrating the structure of an electrical device according to an exemplary embodiment of the present invention. Detailed Implementation

[0040] To make the objectives and implementation methods of the present invention clearer, the exemplary embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the exemplary embodiments of the present invention. Obviously, the exemplary embodiments described are only some embodiments of the present invention, and not all embodiments.

[0041] It should be noted that the brief descriptions of terminology in this invention are merely for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this invention. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0042] In this invention, the terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings are used to distinguish similar or related objects or entities, and do not necessarily imply a specific order or sequence, unless otherwise specified. It should be understood that such terms can be used interchangeably where appropriate.

[0043] The terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device that includes a range of components is not necessarily limited to all of the components that are clearly listed, but may include other components that are not clearly listed or that are inherent to such product or device.

[0044] Figure 1This is a schematic diagram illustrating an application scenario of the present invention according to an exemplary embodiment. For example... Figure 1 As shown, the power supply circuit 10 can be used to supply power to other electrical systems. For example, this application scenario may include: the power supply circuit 10, the control system 20, and the power system 30; the control system can also be called a data processing circuit, and the power system can also be called a power circuit. The output terminals of the power supply circuit 10 are electrically connected to the control system 20 and the power system 30, respectively. The power supply circuit 10 is used to convert AC mains power into DC power and supply power to the control system 20 and the power system 30.

[0045] For example, Figure 2 This is a detailed structural diagram illustrating an application scenario of the present invention according to an exemplary embodiment. Figure 1 On the basis of, such as Figure 2 As shown, the power supply circuit 10 includes: a filter circuit 110, a power frequency rectifier circuit 120, a power factor correction (PFC) circuit 130, a DC-DC converter circuit 140, and an output rectifier circuit 150; wherein, the DC-DC converter circuit 140 includes a first DC / DC converter 141 and a second DC / DC converter 142, and the output rectifier circuit 150 includes a first output rectifier circuit 151 and a second output rectifier circuit 152.

[0046] The filter circuit 110 has its input terminal connected to the mains power supply, its output terminal connected to the input terminal of the power frequency rectifier circuit 120, its output terminal connected to the input terminal of the PFC circuit 130, and its output terminal connected to the input terminals of the first DC / DC converter 141 and the second DC / DC converter 142. The output terminal of the first DC / DC converter 141 is connected to the input terminal of the first output rectifier circuit 151, which is also connected to the input terminal of the control system 20. The output terminal of the second DC / DC converter 142 is connected to the input terminal of the second output rectifier circuit 152, which is also connected to the input terminal of the power system 30.

[0047] Based on this, refer to Figure 3 The voltage conversion implemented by the power supply circuit 10 will be illustrated by way of example.

[0048] For example, Figure 3 This is a waveform diagram illustrating a voltage transformation according to an exemplary embodiment of the present invention. Figure 2 On the basis of, such as Figure 3As shown, mains power typically provides alternating current (AC) Vac, which can be represented as a sinusoidal signal; for example, mains power can provide 220V AC. The AC Vac provided by mains power contains some noise signals. Filter circuit 110 can filter out these noise signals, preventing them from damaging subsequent circuits. Then, the power frequency rectifier circuit 120 rectifies the AC output from filter circuit 110, that is, it rectifies the AC after the noise signals have been filtered out, obtaining... Figure 3 The DC current Vdc shown is output to the PFC circuit 130. The PFC circuit 130 then controls the current waveform of the DC current Vdc output from the power frequency rectifier circuit 120 to synchronize it with the voltage waveform of the DC current Vdc output from the power frequency rectifier circuit 120. Subsequently, the DC-DC converter circuit 140 performs a step-down process on the synchronized DC current; specifically, the first DC / DC converter 141 can step down the synchronized DC current output from the PFC circuit 130 to obtain the following... Figure 3 The buck synchronous DC power Vdc1 shown is output by the first DC / DC converter 141 and is suitable for the control system 20. The second DC / DC converter 142 can step down the synchronous DC power output by the PFC circuit 130 to obtain... Figure 3 The buck synchronous DC power Vdc2 shown is output from the second DC / DC converter 142 and is suitable for the power system 30. The first output rectifier circuit 151 rectifies the buck synchronous DC power Vdc1 output from the first DC / DC converter 141 and outputs the rectified buck synchronous DC power Vdc1 to the control system 20. Thus, the power supply circuit 10 can convert AC power Vac to DC power Vdc1 suitable for the control system 20 and supply power to the control system 20. The second output rectifier circuit 152 rectifies the buck synchronous DC power Vdc2 output from the second DC / DC converter 142 and outputs the rectified buck synchronous DC power Vdc2 to the power system 30. Thus, the power supply circuit 10 can also convert AC power Vac to DC power Vdc2 suitable for the power system 30 and supply power to the power system 30.

[0049] For example, the control system 20 and power system 30 described above can be systems integrated into electrical appliances, such as televisions, washing machines, and refrigerators. With the increasing intelligence of various electrical appliances, control systems typically monitor the operating status of these appliances in real time, collect and store large amounts of data, and use this stored data for control feedback to achieve more intelligent control. Therefore, the control systems of these electrical appliances cannot tolerate sudden power outages during data storage and communication with higher-level control systems to avoid data loss or even damage to the storage devices. To address this, the control system needs to receive power outage information (also known as power failure information) before a power failure (also known as a power cut-off) occurs and take corresponding power failure protection actions (power failure protection actions).

[0050] In related technologies, there are two main methods for identifying power failure information, both based on the main control board in the electrical device. Taking a television as an example, the power board containing the power supply circuit is electrically connected to the main control board via a separate signal line. The AC power failure signal corresponding to the power supply circuit is transmitted to the main control board through this signal line. When the AC power fails, the level of the AC power failure signal transmitted to the main control board changes, for example, a high-to-low level transition occurs. After receiving the power failure information, the main control board immediately executes the storage device protection action. After the protection action ends, it then controls the electrical device to shut down. The disadvantage of this method is that it requires a separate signal line from the power board to the main control board, resulting in a high complexity of the circuit structure.

[0051] Another method involves the main control board continuously monitoring the power supply board's output voltage. When the detected output voltage drops to a certain level, it's considered an AC power failure, triggering the storage device protection mechanism. The drawback of this method is that after an AC power failure, the voltage in the power supply circuit's input capacitor decreases. Because the input voltage decreases while the output voltage remains constant, the power supply circuit's gain becomes insufficient, leading to shutdown. The output hold-up time relies solely on the output electrolytic capacitor. Therefore, electrical devices using this method for power-down protection require a large-capacity output electrolytic capacitor. However, in switching power supply systems, the output capacitor cannot be increased indefinitely. If the capacity is too large, it cannot charge to the output voltage value in time during power-up, preventing feedback and causing startup failure. Therefore, only the largest possible output capacitor can be used. Relying on such an output electrolytic capacitor only provides short-term protection. Thus, for some electrical devices requiring longer-term power-down protection, the output electrolytic capacitor-based method cannot meet the power-down protection requirements.

[0052] To address at least one of the aforementioned problems, embodiments of the present invention propose a power supply circuit and an electrical device that identify AC power failures and extend the output hold-up time through voltage modulation or operating frequency modulation, without requiring a separate AC power failure signal line to the main control board or a significant increase in the output electrolytic capacitor.

[0053] For example, embodiments of the present invention provide a power supply circuit for use in electrical appliances such as televisions, washing machines, and refrigerators, to control the power failure sequence in a switching power supply and extend the output hold-up time to meet the requirements of power failure protection. Specifically, a detection circuit and a control circuit are added to the power supply circuit in the related art. The detection circuit performs AC power failure detection and outputs a power failure signal to the control circuit when a first preset duration of AC power failure is detected. The control circuit performs voltage modulation or operating frequency modulation based on the received power failure signal, so that the hold-up time of the voltage at the output terminal of the power supply circuit, i.e., the voltage output to the control system, is extended to a second preset duration, thereby facilitating the completion of the power failure protection action and meeting the power failure protection requirements.

[0054] The power supply circuit and electrical equipment provided in the embodiments of the present invention will be described exemplarily below with reference to the accompanying drawings.

[0055] For example, Figure 4 This is a schematic diagram illustrating the structure of a power supply circuit according to an exemplary embodiment of the present invention. Figure 4 As shown, the power supply circuit 10 includes a detection circuit 170 and a control circuit 190; in this paper, the detection circuit is the AC power failure detection circuit; the control circuit is the switching power supply control circuit, also known as the output control circuit.

[0056] The detection circuit 170 has an input terminal connected to AC power, meaning it is an AC input. For example, this AC input may correspond to AC power, such as mains power, or to filtered AC power, or to AC power after filtering and rectification. This is not limited here, but will be illustrated exemplarily below.

[0057] The output of the detection circuit 170 is connected to the control terminal of the control circuit 190, and the output of the control circuit 190 is connected to the control system 20 of the electrical equipment. For example, the electrical equipment can be a television or other electrical appliance, but is not limited thereto.

[0058] In this embodiment of the invention, the detection circuit 170 is used to output a power failure signal after detecting a first preset time of AC power failure; the control circuit 190 is used to perform voltage modulation or operating frequency modulation based on the power failure signal, so that the holding time of the voltage transmitted to the control system 20 is extended to a second preset time.

[0059] Therefore, the detection circuit 170 can detect AC power, and when it detects an AC power failure, based on its own circuit structure characteristics, it outputs a power failure signal for a period of time after detecting the AC power failure. Correspondingly, the control circuit 190 receives the power failure signal output by the detection circuit 170, that is, it receives the power failure signal after the first preset time of AC power failure, and performs voltage modulation or operating frequency modulation based on the AC power failure signal, so that the voltage output by the power supply circuit, that is, the voltage output to the control system 20, is maintained for a period of time extended to a second preset time. Since the second preset time corresponds to a longer duration, it is beneficial for the control system 20 and related systems such as the main control board in the electrical equipment to complete the power failure protection action within this longer duration, thereby meeting the power failure protection requirements.

[0060] Voltage modulation can be achieved by using a power-down signal to pull the standby signal of the main control board low. The main control board can then determine if an AC power failure has occurred by switching the standby signal level. Specifically, when AC power fails, the standby signal is pulled low, and the high level output by the main control board is pulled low, indicating an AC power failure. At this time, although the input voltage of the power supply circuit decreases, the output voltage also decreases, allowing the power supply circuit to continue operating for a period of time. This extends the output hold-up time, ensuring that the output time meets the requirements of the main control board and the control system for executing power-down protection actions.

[0061] The operating frequency modulation can utilize a power-down signal as a control signal. Upon receiving the power-down signal, the operating frequency is fixed. As the input voltage decreases, the operating frequency no longer decreases, and the gain remains constant. Consequently, when the input voltage decreases, the output voltage also decreases, eliminating the need for protection due to excessive gain. Therefore, the power supply circuit can continue to operate under low input voltage conditions, maximizing the transfer of energy stored in the input electrolytic capacitor to the output terminal, thereby extending the output hold time. This ensures that the output time meets the requirements of the main control board and control system for executing power-down protection actions.

[0062] The implementation of voltage modulation and operating frequency modulation will be illustrated later with examples of the power supply circuit structure.

[0063] This invention provides a power supply circuit 10, which includes a detection circuit 170 and a control circuit 190. The detection circuit 170 can detect AC power and output a power failure signal after detecting a first preset time of AC power failure. The control circuit 190 receives the power failure signal and performs voltage modulation or operating frequency modulation based on the power failure signal to extend the output holding time of the power supply circuit 10 to a second preset time, thereby increasing the output holding time of the power supply circuit and helping to meet the power failure protection requirements.

[0064] In some embodiments of the present invention Figure 5 This is a schematic diagram illustrating another power supply circuit according to an exemplary embodiment of the present invention. Figure 2 and Figure 4 On the basis of, such as Figure 5 As shown, the power supply circuit 10 may further include a rectifier circuit 160; wherein, the rectifier circuit 160 is connected between the detection circuit 170 and the filter circuit 110, and is used to rectify the filtered AC power and transmit the rectified AC power to the detection circuit 170 so that the detection circuit 170 can detect the filtered and rectified AC power.

[0065] In some embodiments of the present invention Figure 6 This is a schematic diagram illustrating the structure of another power supply circuit according to an exemplary embodiment of the present invention. Figure 6 As shown, in the power supply circuit 10, the detection circuit 170 includes a detection sub-circuit 171 and a coupling sub-circuit 172; the output terminal of the detection sub-circuit 171 is electrically connected to the input terminal of the coupling sub-circuit 172, and the output terminal of the coupling sub-circuit 172 is connected to the control terminal of the control circuit 190; the detection sub-circuit 171 is used to maintain the output voltage of the detection sub-circuit 171 greater than or equal to a preset voltage for a first preset duration when the voltage of the AC power after full-wave rectification decreases; the coupling sub-circuit 172 is used to output a power-down signal when the output voltage of the detection circuit 171 is less than the preset voltage; the first preset duration is greater than or equal to the trough duration of the AC power after full-wave rectification.

[0066] In some embodiments of the present invention, the power supply circuit 10 includes: a detection sub-circuit 171, a coupling sub-circuit 172, and a control circuit 190. The output terminal of the detection sub-circuit 171 is electrically connected to the input terminal of the coupling sub-circuit 172, the output terminal of the coupling sub-circuit 172 is electrically connected to the control terminal of the control circuit 190, and the output terminal of the control circuit 190 is electrically connected to the control system 20.

[0067] Among them, the detection sub-circuit 171 is used to maintain the output voltage ACON of the detection sub-circuit 171 greater than or equal to the preset voltage U for a first preset time period when the voltage of the AC power after full-wave rectification decreases, and output a signal to the coupling sub-circuit 172 when the output voltage ACON is less than the preset voltage U.

[0068] The coupling sub-circuit 172 is used to receive the signal output by the detection sub-circuit 171 when the output voltage ACON is less than the preset voltage U, and output a power-down signal accordingly.

[0069] The control circuit 190 is used to perform voltage modulation or operating frequency modulation based on the power-down signal when the output voltage ACON is less than the preset voltage U, that is, when a power-down signal is received, so as to extend the output holding time to the second preset time.

[0070] In some embodiments of the present invention, such as Figure 6 As shown, the power supply circuit 10 may further include: a rectifier circuit 160, a detection sub-circuit 171, a coupling sub-circuit 172, and a control circuit 190.

[0071] The input terminal of the rectifier circuit 160 can be connected to the mains power through the filter circuit 110, such as... Figure 6 As shown, the filter circuit 110 is used to filter out noise signals in the AC power, thereby preventing noise signals in the AC power Vac from damaging the rectifier circuit 160 and other subsequent circuits; or, the input terminal of the rectifier circuit 160 can be directly connected to the mains power, which is not limited here.

[0072] For example, the rectifier circuit 160 may be a full-wave rectifier circuit, such as... Figure 7 As shown, the rectifier circuit 160 includes two diodes. The anode of one diode is electrically connected to the positive terminal of the AC power supply, and the anode of the other diode is electrically connected to the negative terminal of the AC power supply. The cathodes of both diodes are electrically connected to the output terminal of the rectifier circuit 160. The waveform of the AC power supply Vac input to the rectifier circuit 160 is as follows: Figure 3 As shown, after full-wave rectification by rectifier circuit 160, the resulting alternating current Vac' is as follows: Figure 8 As shown, the direction of the rectified alternating current Vac' is positive.

[0073] In this circuit, rectifier circuit 160 transmits the full-wave rectified AC power Vac' to detection sub-circuit 171. As the voltage of AC power Vac' decreases from its maximum to its minimum, the energy storage unit in detection sub-circuit 171 begins to discharge, and the output voltage ACON of detection sub-circuit 171 begins to decrease. Detection sub-circuit 171 can simultaneously supply power to control system 20 and power system 30. When the output voltage ACON of detection sub-circuit 171 decreases to a value greater than or equal to a preset voltage U, the required time is greater than a first preset time, for example, the first preset time can be the time specified by relevant national standards (20ms). If the first preset time is exceeded, the output voltage ACON of detection sub-circuit 171 may decrease to a value less than the preset voltage U, indicating an AC power failure. At this time, detection sub-circuit 171 transmits a signal to coupling sub-circuit; simultaneously, detection sub-circuit 171 can output its stored energy to control system 20, continuously supplying power to control system 20.

[0074] Correspondingly, the coupling sub-circuit 172 can receive the output voltage ACON of the detection sub-circuit 171, and when the received output voltage ACON is less than the preset voltage U, that is, when AC power failure occurs, the coupling sub-circuit 172 outputs a power failure signal.

[0075] In some embodiments of the present invention, the control terminal of the control circuit 190 can be electrically connected to the output terminal of the detection sub-circuit 171. The control circuit 190 is controlled by the output voltage ACON of the detection sub-circuit 171. When the output voltage ACON is less than the preset voltage U, that is, when AC power failure occurs, voltage modulation or operating frequency modulation is performed. At this time, the power supply circuit 10 will continue to supply power to the control system 20 to extend the output holding time.

[0076] In this embodiment of the invention, the power supply circuit 10 includes a detection sub-circuit 171, a coupling sub-circuit 172, and a control circuit 190. The output terminal of the detection sub-circuit 171 is electrically connected to the input terminal of the coupling sub-circuit 172 and the control terminal of the control circuit 190. The output terminal of the control circuit 190 is electrically connected to the control system 20. When the voltage of the AC power after full-wave rectification decreases, the detection sub-circuit 171 can maintain its output voltage greater than or equal to a preset voltage for a first preset time period, and supply power to the control system 20 when the output voltage is less than the preset voltage. The coupling sub-circuit 172 can output a power-down signal when the output voltage is less than the preset voltage. The control circuit 190 can perform voltage modulation or operating frequency modulation when the output voltage is less than the preset voltage, i.e., when it receives the power-down signal, to extend the output hold time and meet the power-down protection requirements.

[0077] In some other embodiments, the control terminal of the control circuit 190 can be electrically connected to the output terminal of the coupling sub-circuit 172. When the coupling sub-circuit 172 outputs a power-down signal, voltage modulation or operating frequency modulation is performed. At this time, the power supply circuit 10 will continuously supply power to the control system 20 to extend the output hold time.

[0078] In other embodiments, when the control circuit 190 receives a power failure signal, it can also control the power system 30 to be shut down. That is, the control circuit 190 can shut down the power system when the AC power fails, so that the power circuit 10 supplies power to the control system 20 when the AC power fails, but does not supply power to the power system 30. This avoids the power system 30 consuming the electrical energy stored in the power circuit 10, and can provide sufficient electrical energy to the control system 20 to complete the power failure protection. In addition, there is no need to set a large capacity capacitor in the power circuit 10, which can avoid the equipment startup failure caused by a large capacitor, thereby balancing the timeliness of power failure protection and the stability of equipment startup.

[0079] In some embodiments of the present invention, the first preset duration in the above embodiments is greater than or equal to the trough duration of the alternating current after full-wave rectification.

[0080] For example, the first preset duration can be greater than or equal to the trough duration of Vac'. That is, when the AC power Vac' is in the trough period, the output voltage ACON of the detection sub-circuit 171 has not yet dropped below the preset voltage U. The AC power Vac' then switches to the peak period and begins to charge the detection sub-circuit 171, causing the output voltage ACON of the detection sub-circuit 171 to start rising. In this way, false detection of AC power failure caused by the trough of AC power can be avoided.

[0081] For example, such as Figure 8 As shown, during the periods 0-t1, t2-t3, and t4-t5, the AC current Vac' is in a trough, and the detection sub-circuit 171 is in a discharging state. As the charge is released, the output voltage ACON of the detection sub-circuit 171 decreases, but the output voltage ACON is still greater than or equal to the preset voltage U. Therefore, the output voltage ACOFF of the coupling sub-circuit 172 remains at a high level. During the periods t1-t2 and t3-t4, the AC current Vac' transitions from a trough to a peak, and the detection sub-circuit 171 transitions from a discharging state to a charging state. The output voltage ACON of the detection sub-circuit 171 gradually increases until it reaches a stable state, and the output voltage ACOFF of the coupling sub-circuit 172 remains at a high level. Thus, when the AC current Vac' is in a trough, the coupling sub-circuit 172 will not output a power-down signal. An AC power failure occurs at time t6. The period from t6 to t7 is the first preset duration. During this period, the output voltage ACON of the detection sub-circuit 171 decreases, but it remains greater than or equal to the preset voltage U. Therefore, the output voltage ACOFF of the coupling sub-circuit 172 remains high. At time t7, the output voltage ACON of the detection sub-circuit 171 is less than the preset voltage U, and the output voltage ACOFF of the coupling sub-circuit 172 changes from high to low, outputting a power failure signal.

[0082] At this time, the control circuit 190 performs voltage modulation and operating frequency modulation based on the power failure signal to extend the holding time of the voltage output to the control system 20. That is, the input voltage Vct of the control system 20 remains at a high level, which continuously provides power to the control system 20, so that the control system 20 has enough time to perform power failure protection.

[0083] Meanwhile, under the action of the power failure signal, the control circuit 190 can also shut down the power system 30. The input voltage Vpo of the power system 30 then changes from high level to low level, no longer consuming the electrical energy stored in the power supply circuit 10 (such as the detection sub-circuit 171 or other energy storage capacitors). This helps to further extend the holding time of the voltage output to the control system 20, so that the control system 20 has enough time to perform the power failure protection action.

[0084] In this embodiment of the invention, by setting a first preset duration greater than or equal to the trough duration of the AC power after full-wave rectification, false detection of AC power failure caused by the trough of the AC power can be avoided, thereby improving the accuracy of AC power failure detection.

[0085] In some embodiments of the present invention Figure 9 This is a schematic diagram illustrating the structure of a coupling sub-circuit according to an exemplary embodiment of the present invention. For example... Figure 9 As shown, the coupling sub-circuit 172 includes: an optocoupler OC, a first resistor R1, a second resistor R2, a third resistor R3, and a first capacitor C1.

[0086] The first end of the optocoupler OC is electrically connected to the high level Vcc through the first resistor R1. The second end of the optocoupler OC is electrically connected to the output of the detection sub-circuit 171. The third end of the optocoupler OC is electrically connected to the output of the power supply circuit 10 through the second resistor R2. The fourth end of the optocoupler OC is electrically connected to the first end of the third resistor R3 and the first end of the first capacitor C1. The second end of the third resistor R3 and the second end of the first capacitor C1 are both grounded.

[0087] For example, such as Figure 9 As shown, the first and second terminals of the optocoupler OC are electrically connected to the positive and negative terminals of the light-emitting diode N, respectively, and the third and fourth terminals of the optocoupler OC are electrically connected to the two ends of the phototransistor T, respectively. When the output voltage ACON of the detection sub-circuit is less than the preset voltage U, the first and second terminals of the optocoupler OC are disconnected, meaning the light-emitting diode N does not emit light, and the phototransistor T is in the off state, meaning the third and fourth terminals of the optocoupler OC are disconnected. Thus, the fourth terminal of the optocoupler OC is at a low level, and the output voltage ACOFF of the coupling sub-circuit 172 is at a low level, i.e., a power-down signal is output. When the output voltage ACON of the detection sub-circuit is greater than or equal to the preset voltage U, the first and second terminals of the optocoupler OC are turned on, meaning the light-emitting diode N emits light, and the phototransistor T is in the on state, meaning the third and fourth terminals of the optocoupler OC are turned on. Thus, the fourth terminal of the optocoupler OC is at a high level, and the output voltage ACOFF of the coupling sub-circuit 172 is at a high level, i.e., no power-down signal is output.

[0088] In some embodiments of the present invention Figure 10 This is a schematic diagram illustrating another coupling sub-circuit according to an exemplary embodiment of the present invention. Figure 9 Based on the illustrated embodiments, as Figure 10As shown, the coupling sub-circuit 172 may further include: a first comparator ADC1, the first input terminal of the first comparator ADC1 being electrically connected to the output terminal of the detection sub-circuit, the second input terminal of the first comparator ADC1 being electrically connected to a preset voltage U, and the output terminal of the first comparator ADC1 being electrically connected to the first terminal of the optocoupler OC. The first comparator ADC1 is used to compare the output voltage ACON of the detection sub-circuit with the preset voltage U.

[0089] For example, such as Figure 10 As shown, the reference voltage Vref is electrically connected to the second input terminal of the first comparator ADC1 through the first auxiliary voltage divider resistor R1'. The second input terminal of the first comparator ADC1 is also electrically connected to the second auxiliary voltage divider resistor R2'. The reference voltage Vref, after being divided by the first auxiliary voltage divider resistor R1' and the second auxiliary voltage divider resistor R2', can input a preset voltage U to the second input terminal of the first comparator ADC1. The output voltage ACON of the detection sub-circuit is input to the first input terminal of the first comparator ADC1. The output terminal of the first comparator ADC1 is electrically connected to the first terminal of the optocoupler OC through the first resistor R1. If the output voltage ACON of the detection sub-circuit is less than the preset voltage U, the first comparator ADC1 outputs a low level, that is, the positive terminal of the light-emitting diode N is at a low level, so the light-emitting diode N does not emit light. Therefore, the third and fourth terminals of the optocoupler OC are disconnected, and the output voltage ACOFF of the coupling sub-circuit 172 is at a low level, that is, a power-down signal can be output.

[0090] In some embodiments of the present invention Figure 11 This is a schematic diagram illustrating the structure of another coupling sub-circuit according to an exemplary embodiment of the present invention. Figure 9 Based on the illustrated embodiments, as Figure 11 As shown, the coupling sub-circuit 172 may further include: a first comparator ADC1, the first input terminal of the first comparator ADC1 being electrically connected to the output terminal of the detection sub-circuit, the second input terminal of the first comparator ADC1 being electrically connected to a preset voltage U, and the output terminal of the first comparator ADC1 being electrically connected to the second terminal of the optocoupler OC. The first comparator ADC1 is used to compare the output voltage ACON of the detection sub-circuit with the preset voltage U.

[0091] For example, such as Figure 11As shown, the reference voltage Vref is electrically connected to the second input terminal of the first comparator ADC1 through the first auxiliary voltage divider resistor R1'. The second input terminal of the first comparator ADC1 is also electrically connected to the second auxiliary voltage divider resistor R2'. The reference voltage Vref, after being divided by the first auxiliary voltage divider resistor R1' and the second auxiliary voltage divider resistor R2', can input a preset voltage U to the second input terminal of the first comparator ADC1. The output voltage ACON of the detection sub-circuit is input to the first input terminal of the first comparator ADC1. The output terminal of the first comparator ADC1 is electrically connected to the control terminal of transistor T1 and the first terminal of the fourth auxiliary voltage divider resistor R4' through the third auxiliary voltage divider resistor R3'. The first terminal of transistor T1 is electrically connected to the second terminal of optocoupler OC, and the second terminal of transistor T1 is electrically connected to the second terminal of the fourth auxiliary voltage divider resistor R4'. If the output voltage ACON of the detection sub-circuit is less than the preset voltage U, the first comparator ADC1 outputs a low level, that is, the control terminal of transistor T1 is at a low level. Then the first and second terminals of transistor T1 are disconnected. As a result, the two ends of the light-emitting diode N are not conducting, so the light-emitting diode N does not emit light. The output voltage ACOFF of the coupling sub-circuit 172 is at a low level, that is, a power-down signal can be output.

[0092] In some embodiments of the present invention Figure 12 This is a schematic diagram illustrating the structure of another coupling sub-circuit according to an exemplary embodiment of the present invention. Figure 9 Based on the illustrated embodiments, as Figure 12 As shown, the coupling sub-circuit 172 may further include: a first comparator ADC1, the first input terminal of the first comparator ADC1 being electrically connected to the output terminal of the detection sub-circuit, the second input terminal of the first comparator ADC1 being electrically connected to a preset voltage U, and the output terminal of the first comparator ADC1 being electrically connected to the second terminal of the optocoupler OC and the first terminal of the optocoupler OC. The first comparator ADC1 is used to compare the output voltage ACON of the detection sub-circuit with the preset voltage U.

[0093] For example, such as Figure 12 As shown, the reference voltage Vref is electrically connected to the second input terminal of the first comparator ADC1 through the first auxiliary voltage divider resistor R1'. The second input terminal of the first comparator ADC1 is also electrically connected to the second auxiliary voltage divider resistor R2'. The reference voltage Vref, after being divided by the first auxiliary voltage divider resistor R1' and the second auxiliary voltage divider resistor R2', can input a preset voltage U to the second input terminal of the first comparator ADC1. The output voltage ACON of the detection sub-circuit is input to the first input terminal of the first comparator ADC1. The output terminal of the first comparator ADC1 is electrically connected to the first terminal of the optocoupler OC through the diode D1. The output terminal of the first comparator ADC1 is also electrically connected to the second terminal of the optocoupler OC.

[0094] If the output voltage ACON of the detection sub-circuit is less than the preset voltage U, the first comparator ADC1 outputs a high level, meaning the anode of diode D1 is at a high level. At this time, if the voltage across the anode of diode D1 is greater than the voltage across its cathode, diode D1 conducts, and the voltages across LED N are the same, meaning LED N does not emit light. The phototransistor T is disconnected, and the output voltage ACOFF of the coupling sub-circuit 172 is low, thus a power-down signal can be output. If the voltage across the anode of diode D1 is less than or equal to the voltage across its cathode, diode D1 is disconnected, and the voltages across LED N are both high, then LED N does not emit light, the phototransistor T is disconnected, and the output voltage ACOFF of the coupling sub-circuit 172 is low, thus a power-down signal can be output.

[0095] The above embodiments exemplify the circuit structure that can be used to generate a power-down signal when the output voltage ACON of the detection sub-circuit is less than the preset voltage U.

[0096] In some embodiments of the present invention, the circuit structure of the coupling sub-circuit can be configured such that when the output voltage ACON of the detection sub-circuit is greater than a preset voltage U, a power-down signal is generated.

[0097] For example, Figure 13 This is a schematic diagram illustrating the structure of another coupling sub-circuit according to an exemplary embodiment of the present invention. Figure 13 As shown, if the output voltage ACON of the detection sub-circuit is greater than the preset voltage U, the first comparator ADC1 outputs a high level, meaning the anode of diode D1 is at a high level. At this time, if the voltage at the anode of diode D1 is greater than the voltage at the cathode, diode D1 conducts, and the voltages across LED N are the same, meaning LED N does not emit light. The phototransistor T is disconnected, and the output voltage ACOFF of the coupling sub-circuit 172 is low, thus a power-down signal can be output. If the voltage at the anode of diode D1 is less than or equal to the voltage at the cathode, diode D1 is disconnected, and the voltages across LED N are both high, then LED N does not emit light, the phototransistor T is disconnected, and the output voltage ACOFF of the coupling sub-circuit 172 is low, thus a power-down signal can be output. For example... Figure 14 This is a schematic diagram illustrating the structure of another coupling sub-circuit according to an exemplary embodiment of the present invention. Figure 14 As shown, if the output voltage ACON is greater than the preset voltage U, the first comparator ADC1 outputs a high level, then the voltages across the LED N are both high, so the LED N does not emit light, the phototransistor T is disconnected, and the output voltage ACOFF of the coupler circuit 172 is low, which means a power-down signal can be output.

[0098] In some embodiments of the present invention Figure 15This is a schematic diagram illustrating the structure of another coupling sub-circuit according to an exemplary embodiment of the present invention. Figure 9 Based on the illustrated embodiments, as Figure 15 As shown, the coupling sub-circuit 172 further includes: a third switch K3; the control terminal of the third switch K3 is electrically connected to the output terminal of the detection sub-circuit 171, the first terminal of the third switch K3 is electrically connected to the second terminal of the optocoupler OC, and the second terminal of the third switch K3 is electrically connected to the equipotential point; the third switch K3 is used to disconnect the first and second terminals of the third switch K3 when the output voltage ACON of the detection sub-circuit is less than the preset voltage U.

[0099] For example, such as Figure 15 As shown, the third switch K3 can be an N-type metal-oxide-semiconductor (MOS) transistor. If the output voltage ACON of the detection sub-circuit is low, the two ends of the third switch K3 are disconnected, which disconnects the two ends of the light-emitting diode N, that is, the light-emitting diode N does not emit light. In this way, the two ends of the phototransistor T are disconnected, and the output voltage ACOFF of the coupling sub-circuit 172 is low, that is, a power-down signal can be output.

[0100] In other embodiments, the third switch K3 may also be other types of controlled switching transistors, which are not limited here.

[0101] In some embodiments of the present invention Figure 16 This is a schematic diagram illustrating the structure of a detection sub-circuit according to an exemplary embodiment of the present invention, showing an optional circuit structure of the detection sub-circuit in the above embodiment. For example... Figure 16 As shown, the detection sub-circuit 171 includes: a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a Zener diode D2, a fourth switch K4, a fifth switch K5, and a second capacitor C2.

[0102] Specifically, the first end of the fourth resistor R4 is electrically connected to the input terminal of the detection sub-circuit; the control terminal of the Zener diode D2 is electrically connected to the second end of the fourth resistor R4 and the first end of the fifth resistor R5; the first end of the Zener diode D2 is electrically connected to the first end of the sixth resistor R6 and the control terminal of the fourth switch K4; the first end of the fourth switch K4 is electrically connected to the first ends of the seventh resistor R7, the eighth resistor R8, and the control terminal of the fifth switch K5; the first end of the fifth switch K5 is electrically connected to the first end of the ninth resistor R9; the second ends of the sixth resistor R6 and the fourth switch K4 are both electrically connected to the high level Vcc; the second ends of the seventh resistor R7, the ninth resistor R9, and the first end of the second capacitor C2 are all electrically connected to the output terminal of the detection sub-circuit; and the second ends of the fifth resistor R5, the Zener diode D2, the eighth resistor R8, the fifth switch K5, and the second capacitor C2 are all electrically connected to the equipotential point.

[0103] For example, such as Figure 16 As shown, the rectified AC current Vac' is divided by resistors R4 and R5 to generate V1, which is then input to Zener diode D2. When V1 is higher than the voltage threshold (e.g., 2.5V), Zener diode D2 conducts, switch K4 turns on, and the high-level voltage Vcc charges capacitor C2 through resistor R7. The output voltage ACON of the detection sub-circuit is higher than the preset voltage U. When V1 is lower than the voltage threshold, switch K4 turns off, switch K5 turns on, and capacitor C2 discharges through resistor R9 and switch K5. The resistance values ​​of resistors R9 and R7 are adjusted so that the discharge time of capacitor C2 is much longer than the charging time. Furthermore, the time required for the output voltage ACON of the detection sub-circuit to drop to the preset voltage U is greater than the first preset time. For example, the first preset time can be 20ms as specified in relevant standards, thereby avoiding false detection of AC power loss during troughs and allowing a power loss signal to be issued according to the first preset time.

[0104] In some embodiments of the present invention Figure 17 This is a schematic diagram illustrating the structure of another detection sub-circuit according to an exemplary embodiment of the present invention. Figure 16 Based on the illustrated embodiments, as Figure 17 As shown, the detection sub-circuit 171 includes: a second comparator ADC2, a sixth switch K6, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, and a third capacitor C3.

[0105] Among them, the first end of the tenth resistor R10 is electrically connected to the input end of the detection sub-circuit, the second end of the tenth resistor R10 is electrically connected to the first input end of the second comparator ADC2 and the first end of the eleventh resistor R11, the second input end of the second comparator ADC2 is electrically connected to the reference voltage Vref, the output end of the second comparator ADC2 is electrically connected to the control end of the sixth switch K6 and the first end of the twelfth resistor R12, the first end of the sixth switch K6 is electrically connected to the first end of the thirteenth resistor R13, the second end of the thirteenth resistor R13 is electrically connected to the input end of the coupling circuit, the first end of the fourteenth resistor R14 and the first end of the third capacitor C3, the second ends of the eleventh resistor R11, the twelfth resistor R12, the second end of the sixth switch K6 and the second end of the third capacitor C3 are electrically connected to an equipotential point, and the second end of the fourteenth resistor R14 is electrically connected to the reference voltage Vref.

[0106] Exemplarily, as Figure 17 shown, the reference voltage Vref is electrically connected to the sixth auxiliary voltage-dividing resistor R6' through the fifth auxiliary voltage-dividing resistor R5', the reference voltage Vref is also electrically connected to the second input end of the second comparator ADC2 through the fifth auxiliary voltage-dividing resistor R5', and the voltage input to the second end of the second comparator ADC2 after voltage division is a preset voltage U. The alternating current Vac' output by the rectifier circuit is divided by the tenth resistor R10 and the eleventh resistor R11 to generate a sampling voltage V1, and V1 is input to the first input end of the second comparator ADC2. The second comparator ADC2 can compare V1 with the preset voltage U and output V2. For example, as Figure 17 shown, if V1 < U, the V2 output by the second comparator ADC2 is a high level, and if V1 > U, the V2 output by the second comparator ADC2 is a low level.

[0107] V2 controls the on and off of the sixth switch K6. If V2 is a low level, the sixth switch K6 is turned off, and the reference voltage Vref charges the third capacitor C3 through the fourteenth resistor R14; if V2 is a high level, the sixth switch K6 is turned on, and the third capacitor C3 discharges through the sixth switch K6 and the thirteenth resistor R13. The resistance value of the thirteenth resistor R13 is set to be much larger than the resistance value of the fourteenth resistor R14, so that the charging time of the third capacitor C3 is much less than the discharging time. [[ID=eleven]]

[0108] For example, in combination with Figure 12 the coupling sub-circuit 172 shown in Figure 17 and the detection sub-circuit 171 shown in Figure 18When at t1 - t2 and t3 - t4 as shown, V1 > U, the output voltage V2 of the second comparator ADC2 is at a low level, the sixth switch K6 is turned off, and the output voltage ACON of the detection sub - circuit 171 remains at a high level continuously. The voltage at the first input terminal of the first comparator ADC1 is the output voltage ACON, the voltage at the second terminal of the first comparator ADC1 is the preset voltage U, and ACON > U. The output voltage V3 of the first comparator ADC1 is at a low level, the opto - coupler OC is turned on, and the output voltage ACOFF of the coupling circuit is at a high level. During the trough periods 0 - t1, t2 - t3, and t4 - t5 of the rectified alternating current, V1 < U, the output voltage V2 of the second comparator ADC2 is at a high level, the sixth switch K6 is turned on, and the output voltage ACON of the detection sub - circuit 171 continuously decreases but is greater than the preset voltage U. The voltage at the first input terminal of the first comparator ADC1 is the output voltage ACON, the voltage at the second terminal of the first comparator ADC1 is the preset voltage U, and ACON > U. The output voltage V3 of the first comparator ADC1 is at a low level, the opto - coupler OC is turned on, and the output voltage ACOFF of the coupling circuit remains at a high level continuously. After the alternating - current power is cut off, that is, during the t6 - t7 period of the rectified alternating current, V1 < U, the output voltage V2 of the second comparator ADC2 is at a high level, the sixth switch K6 is turned on, and the output voltage ACON of the detection sub - circuit 171 continuously decreases but is greater than the preset voltage U until after t7, the output voltage ACON is less than the preset voltage U. At this time, the output voltage V3 of the first comparator ADC1 changes from a low level to a high level, the opto - coupler is turned off, and the output voltage ACOFF of the coupling circuit changes from a high level to a low level, that is, an output power - off signal is output.

[0109] The above combination Figures 9-18 , an exemplary description of the coupling sub - circuit and the detection sub - circuit in the detection circuit is given. Next, in combination with Figure 19 and Figure 21 , an exemplary description of the working - frequency modulation and voltage modulation of the control circuit is given respectively.

[0110] In some embodiments of the present invention, the control circuit 190 includes a power supply controller; the power supply controller sets a power - off working mode; in the power - off working mode, the working frequency of the resonant loop corresponding to the power supply circuit is a preset value; the power supply controller is used to switch to the power - off working mode based on the power - off signal to achieve working - frequency modulation.

[0111] In this embodiment, the operating mode is primarily determined by the operating frequency and may include a normal operating mode and a power-down operating mode. In normal operating mode, the operating frequency changes with the input voltage; in power-down operating mode, the operating frequency is a preset value, meaning it no longer changes with the input voltage but remains a fixed value. The switching of operating modes is based on a power-down signal. Specifically, the power controller can switch the operating mode based on the power-down signal, for example, switching from normal operating mode to power-down operating mode, so that the operating frequency becomes the preset value, meaning the frequency no longer changes; at this time, the gain also remains fixed, so when the input voltage decreases, the output voltage also decreases. Since there is no longer a protection mechanism due to excessive gain, the power circuit can continue to operate under conditions of lower input voltage, and the energy stored in the input electrolytic capacitor in the power circuit can be transferred to the output to the maximum extent, thus extending the output time.

[0112] Specifically, let's take an LLC circuit as an example of a power supply circuit.

[0113] As can be seen from the working principle of LLC:

[0114]

[0115] Where Vo represents the output voltage, V IN G represents the input voltage, and G represents the LLC resonant loop gain. When the AC power is lost, the input voltage decreases. As shown in the above equation, the LLC needs to increase its gain to maintain the output voltage.

[0116] For example, Figure 19 The LLC gain curve is derived from... Figure 19 The gain curve shown indicates that the LLC circuit has a maximum gain M. m When the required gain exceeds the maximum gain, the LLC system will stop working as a protection mechanism; and as the gain changes from a smaller gain Mmin to a larger gain Mmax, the operating frequency of the LLC system will decrease as the gain increases.

[0117] Based on this, embodiments of the present invention provide a method to extend the output hold-up time by setting the operating frequency. Specifically, in conjunction with the above, a detection circuit is added to a conventional LLC power supply circuit. When an AC power failure is detected, the detection circuit transmits the power failure information to the control circuit, such as a power controller, specifically an LLC controller. Correspondingly, the LLC controller switches its operating mode based on the power failure signal, switching to a power failure operating mode. In this power failure operating mode, the operating frequency is fixed, and as the input voltage decreases, the operating frequency no longer decreases.

[0118] At the same time, by Figure 19As shown in the gain curve and the working principle of LLC, when the operating frequency remains constant, the gain remains constant; therefore, when the input voltage decreases, the output voltage also decreases.

[0119] Since the LLC system no longer has the over-gain protection to stop working, it can continue to operate under low input voltage conditions, and the energy stored in the LLC input electrolytic capacitor can be transferred to the output to the maximum extent.

[0120] In this embodiment of the invention, a detection circuit is used to detect AC power failure and outputs a power failure signal to the control circuit. The control circuit then changes the operating mode of the power supply circuit, extending the output time without adding an AC power failure signal line or an output capacitor. This maximizes the utilization of the charge in the PFC output electrolytic capacitor, which is beneficial for meeting the power failure protection requirements.

[0121] In some embodiments of the present invention Figure 20 This is a schematic diagram illustrating the structure of another power supply circuit according to an exemplary embodiment of the present invention. Figure 20 As shown, the power supply circuit 10 may further include: a filter circuit 110, a power frequency rectifier circuit 120, a PFC circuit 130, a DC-DC converter circuit 140, and an output rectifier circuit 150 connected in sequence; the filter circuit 110 is used to filter out noise signals in the AC power; the power frequency rectifier circuit 120 is used to rectify the AC power after the noise signals are filtered out to obtain DC power; the PFC circuit 130 is used to control the waveform of the DC power to be synchronized with the waveform of the AC power; the DC-DC converter circuit 140 is used to step down the synchronized DC power; the output rectifier circuit 150 is used to rectify the stepped-down DC power and output the voltage to the control system; the detection circuit 170 is used to detect the AC power after the noise signals are filtered out, and the power controller is built into the DC-DC converter circuit 140.

[0122] In this embodiment, the power supply circuit 10 includes two outputs, respectively connected to the control system 20 and the power system 30. Correspondingly, the DC-DC converter circuit 140 includes a first DC / DC converter 141 and a second DC / DC converter 142, and the output rectifier circuit 150 includes a first output rectifier circuit 151 and a second output rectifier circuit 152. The control system 20 is connected to the PFC circuit 130 via the first output rectifier circuit 151 and the first DC / DC converter, and the power system 30 is connected to the PFC circuit 130 via the second output rectifier circuit 152 and the second DC / DC converter 142. One end of the detection circuit 10 is connected between the filter circuit 110 and the power frequency rectifier circuit 120, and the other end is connected between the PFC circuit 130 and the first DC / DC converter 141. The power controller is built into the first DC / DC converter 141. The detection circuit 110 performs AC power detection. After detecting that the AC power has failed, it transmits the power failure signal to the first DC / DC converter 141. Correspondingly, the power controller in the first DC / DC converter 141 switches the working mode of the power circuit 10 to the power failure working mode based on the power failure signal, and sets the corresponding working frequency to a preset value, thereby realizing frequency modulation, extending the output time, and helping to meet the power failure protection requirements.

[0123] In some embodiments of the present invention Figure 21 This is a schematic diagram illustrating the structure of a control circuit according to an exemplary embodiment of the present invention. Figure 21 As shown, the control circuit 190 also includes a first switch K1 and a second switch K2: the control terminal of the first switch K1 is connected to the control terminal of the control circuit 190, the input terminal of the first switch K1 is connected to the standby signal STB, and the control terminal of the second switch K2 is connected to the control terminal of the control circuit 190. The output terminals of the first switch K1 and the second switch K2 are both grounded. The first switch K1 is used to turn on based on the power-down signal ACOFF and pull down the standby signal STB. The second switch K2 is turned on based on the pulled-down standby signal STB and pulls down the voltage of the output terminal of the control circuit 190 to the target voltage to achieve voltage modulation.

[0124] Specifically, in the power supply circuit, a high-level standby signal STB is input when the electrical device is working normally. When the device is in standby mode, to reduce standby power consumption, the main control board pulls the standby signal STB low, thereby lowering the output voltage Vout of the power supply circuit. For example, taking a television as an example, the output voltage Vout is typically adjusted from 12V to 9V. Based on this, in this embodiment of the invention, the control circuit uses the AC OFF signal corresponding to AC power failure to pull the standby signal STB of the main control board low. The main control board can determine whether AC power has failed by the level transition of the standby signal STB.

[0125] like Figure 21 As shown, the control circuit 190 in this power supply circuit includes a first switch K1 and a second switch K2. When the AC power fails, the power failure signal ACOFF switches to a low-level signal. At this time, the first switch K1 is turned on, and the standby signal STB discharges to ground, pulling the level of the standby signal STB low. Subsequently, the signal at the control terminal of the second switch K2 is converted to a low-level signal, and the second switch K2 is turned on. The output voltage Vout discharges to ground through the second switch K2, pulling the output voltage Vout low, and the main control board can then determine that the AC power has failed. At this time, although the input voltage of the power supply circuit decreases due to the AC power failure, the output voltage also decreases, allowing the power supply circuit to continue operating for a period of time. This extends the output hold-up time, ensuring that the output time meets the power failure protection requirements of the main control board.

[0126] In some embodiments of the present invention, reference continues to be made to... Figure 21 The control circuit 190 further includes a first voltage divider resistor R21, a second voltage divider resistor R22, a third voltage divider resistor R23, a fourth voltage divider resistor R24, and a fifth voltage divider resistor R25; the first voltage divider resistor R21 is connected in series between the control terminal of the first switch K1 and the control terminal of the control circuit 190; the second voltage divider resistor R22 is connected in series between the control terminal of the first switch K1 and ground; the third voltage divider resistor R23 is connected in series between the input terminal of the first switch K1 and the control terminal of the second switch K2; the fourth voltage divider resistor R24 ​​is connected in series between the control terminal of the second switch K2 and ground; and the fifth voltage divider resistor R25 is connected in series between the input terminal of the second switch K2 and the output terminal of the control circuit 190.

[0127] Specifically, compared to the power feedback circuit in related technologies, this embodiment adds a first voltage divider resistor R21, a second voltage divider resistor R22, and a first switch K1. When the AC power fails, this part of the circuit pulls the standby signal STB low, which in turn pulls the output signal Vout of the main control board low. Since the output voltage is reduced at the same time as the input voltage, the power supply circuit can continue to work for a period of time, that is, extend the output hold time, which is beneficial to meet the power failure protection requirements.

[0128] It should be noted that, Figure 21 The feedback signal FB, optocoupler, resistors R26, R27, R29, R30, and capacitors C4 and C5 shown are optional components in the power feedback circuit. In other embodiments, the power feedback circuit may also include other circuit components, which are not limited here.

[0129] The above exemplifies the relevant circuits and working principles of voltage modulation and operating frequency modulation in the control circuit. The following text, in conjunction with... Figure 22 and Figure 23 Explain the optional circuit structures for the control circuit to achieve the power shutdown of the system.

[0130] In some embodiments of the present invention Figure 22 This is a schematic diagram illustrating another control circuit according to an exemplary embodiment of the present invention, such as... Figure 22 As shown, the control circuit 190 includes: a seventh switch K7, the control terminal of the seventh switch K7 is electrically connected to the output terminal of the detection sub-circuit, the first terminal of the seventh switch K7 is electrically connected to the enable terminal EN of the power system, and the second terminal of the seventh switch K7 is electrically connected to the equipotential point.

[0131] The control circuit 190 is used to turn on the first and second terminals of the seventh switch K7 when the output voltage ACON is less than the preset voltage U, and output a non-enable signal to the enable terminal EN of the power system; when the output voltage is greater than ACON or equal to the preset voltage U, the first and second terminals of the seventh switch K7 are turned off, and an enable signal is output to the enable terminal EN of the power system.

[0132] For example, such as Figure 22 As shown, when the output voltage ACON is greater than or equal to the preset voltage U, i.e., when AC power is off, the output voltage ACON of the detection sub-circuit is low. The seventh switch K7 is a P-type MOSFET, so its first and second terminals are turned on, pulling the enable terminal EN of the power system down to a low level. Thus, when the enable terminal EN receives a de-enable signal, the power system is turned off. When the output voltage ACON is greater than or equal to the preset voltage U, i.e., when no AC power is off, the output voltage ACON of the detection sub-circuit is high. Therefore, the first and second terminals of the seventh switch K7 are disconnected, without changing the level of the enable terminal EN of the power system. Thus, when the enable terminal EN receives an enable signal, the power system is turned on.

[0133] In other implementations, the seventh switch K7 can be an N-type MOS transistor, and the output voltage ACON of the detection sub-circuit can be high when the AC power is off.

[0134] In some embodiments of the present invention Figure 23 This is a schematic diagram illustrating the structure of another control circuit according to an exemplary embodiment of the present invention, such as... Figure 23 As shown, the control circuit 190 includes: a seventh switch K7, the control terminal of the seventh switch K7 is electrically connected to the output terminal of the coupling sub-circuit, the first terminal of the seventh switch K7 is electrically connected to the enable terminal EN of the power system, and the second terminal of the seventh switch K7 is electrically connected to the equipotential point.

[0135] The control circuit 190 is used to turn on the first and second terminals of the seventh switch K7 when a power-down signal is output, and output a non-enable signal to the enable terminal EN of the power system; when no power-down signal is output, the first and second terminals of the seventh switch K7 are turned off, and an enable signal is output to the enable terminal EN of the power system.

[0136] For example, such as Figure 23 As shown, the seventh switch K7 is a P-type MOSFET. During AC power failure, the output voltage ACOFF of the coupler circuit is low, indicating a power failure signal. Therefore, the first and second terminals of the seventh switch K7 are turned on, pulling down the enable terminal EN of the power system to a low level. Thus, when the enable terminal EN receives a de-enable signal, the power system is turned off. When no AC power failure occurs, the output voltage ACOFF of the coupler circuit is high, indicating no power failure signal. Therefore, the first and second terminals of the seventh switch K7 are open, without changing the level of the enable terminal EN of the power system. Thus, when the enable terminal EN receives an enable signal, the power system is turned on.

[0137] In other implementations, the seventh switch K7 can be an N-type MOS transistor, and the output voltage ACOFF of the coupler circuit can be high when AC power is off.

[0138] The present invention also provides an electrical device, Figure 24 This is a schematic diagram illustrating the structure of an electrical device according to an exemplary embodiment of the present invention, such as... Figure 24 As shown, the electrical device may include: a display screen 40, a power system 30, a control system 20, and a power supply circuit 10.

[0139] The power system 30 is electrically connected to the display screen 40, the control system 20 is electrically connected to the power system 30, and the output terminal of the power supply circuit 10 is electrically connected to both the power system 30 and the control system 20. The power supply circuit 10 can convert AC mains power into DC power and supply power to the control system 20 and the power system 30 respectively.

[0140] This embodiment merely exemplifies the application of any of the above-described power supply circuits in electrical appliances. In the context of electrical appliances, the power system can be understood as the drive circuit of the electrical appliance, and the control system can be understood as the signal processing circuit of the electrical appliance. In practical applications, the power supply circuit can also be applied to appliances such as refrigerators, washing machines, and air conditioners, and this embodiment of the invention does not impose specific limitations on this.

[0141] For example, the power supply circuit is applied in a washing machine. The power system is the motor circuit, and the control system is the motor control circuit. The power supply circuit can provide power to the motor control circuit and the motor circuit, and can shut off the motor when the AC power fails, so that the power supply circuit will not supply power to the motor circuit, but will continue to supply power to the motor control circuit. In addition, the output hold time is extended by voltage modulation and operating frequency modulation to complete the power failure protection action.

[0142] For another example, the power supply circuit is applied in an air conditioner. The power system is the air conditioner compressor circuit, and the control system is the air conditioner compressor control circuit. The power supply circuit can provide power to the air conditioner compressor control circuit and the air conditioner compressor circuit. When the AC power fails, it can shut off the air conditioner compressor circuit, so that the power supply circuit will not supply power to the air conditioner compressor circuit, but will continue to supply power to the air conditioner compressor control circuit. In addition, the output hold time is extended through voltage modulation and operating frequency modulation to complete the power failure protection action.

[0143] In this embodiment of the invention, the electrical device includes a display screen, a power system, a digital processing circuit, and a power supply circuit. The power system is electrically connected to the display screen and can drive the display screen to display images. The output terminal of the power supply circuit is electrically connected to the power system and the control system. The power supply circuit can convert AC power to DC power and supply power to the power system and the control system. The power supply circuit includes a detection circuit and a control circuit. The input terminal of the detection circuit is connected to AC power, and the output terminal of the detection circuit is connected to the control terminal of the control circuit. The output terminal of the control circuit is connected to the control system of the electrical device. The detection circuit is used to output a power failure signal after detecting a first preset time of AC power failure. The control circuit is used to perform voltage modulation or operating frequency modulation based on the power failure signal to extend the holding time of the voltage transmitted to the control system to a second preset time. This allows the power supply circuit to detect AC power failure using the detection circuit and extend the output holding time using the control circuit based on voltage modulation or operating frequency modulation. Without adding an AC power failure signal line or an output capacitor, the problem of short output holding time during AC power failure is solved, thus meeting the power failure protection requirements.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

[0145] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the embodiments and various different variations of embodiments suitable for specific application considerations.

Claims

1. A power supply circuit, characterized by comprising: The application relates to a power supply circuit. The power supply circuit comprises a detection circuit and a control circuit; An input end of the detection circuit is connected to an alternating current, and an output end of the detection circuit is connected to a control end of the control circuit; and an output end of the control circuit is connected to a control system of an electric device; The detection circuit is used for outputting a power-off signal after detecting that the alternating current is powered off for a first preset time length; and the first preset time length is greater than or equal to a valley time length of the alternating current after full-wave rectification; The control circuit is used for performing frequency modulation based on the power-off signal, so that the voltage transmitted to the control system is kept for a second preset time length; and the working frequency is a preset value.

2. The power supply circuit of claim 1, wherein The control circuit comprises a power supply controller; The power supply controller sets a power-off working mode; in the power-off working mode, the working frequency of a resonance loop corresponding to the power supply circuit is a preset value; The power supply controller is used for switching to the power-off working mode based on the power-off signal, so as to realize frequency modulation.

3. The power supply circuit of claim 2, wherein The application further relates to a power supply circuit. The power supply circuit comprises a filter circuit, a power frequency rectifier circuit, a PFC circuit, a direct-current conversion circuit and an output rectifier circuit which are sequentially connected in an electric manner; The filter circuit is used for filtering out a noise signal in the alternating current; The power frequency rectifier circuit is used for rectifying the alternating current after the noise signal is filtered out, so as to obtain direct current; The PFC circuit is used for controlling the waveform of the direct current to be synchronous with the waveform of the alternating current; The direct-current conversion circuit is used for performing voltage reduction processing on the synchronous direct current; The output rectifier circuit is used for performing rectification processing on the direct current after voltage reduction, so as to output voltage to the control system; The detection circuit is used for detecting the alternating current after the noise signal is filtered out; and the power supply controller is built in the direct-current conversion circuit.

4. The power supply circuit according to any one of claims 1 to 3, characterized by The detection circuit comprises a detection sub-circuit and a coupling sub-circuit; An output end of the detection sub-circuit is electrically connected to an input end of the coupling sub-circuit; and an output end of the coupling sub-circuit is connected to a control end of the control circuit; The detection sub-circuit is used for maintaining the output voltage of the detection sub-circuit to be greater than or equal to a preset voltage within a first preset time length when the voltage of the alternating current after full-wave rectification is reduced; The coupling sub-circuit is used for outputting the power-off signal when the output voltage of the detection sub-circuit is less than the preset voltage.

5. The power supply circuit of claim 4, wherein, The coupling sub-circuit comprises an optoelectronic coupler, a first resistor, a second resistor, a third resistor and a first capacitor; A first end of the optoelectronic coupler is electrically connected to a high level through the first resistor; a second end of the optoelectronic coupler is electrically connected to an output end of the detection sub-circuit; a third end of the optoelectronic coupler is electrically connected to an output end of the power supply circuit through the second resistor; a fourth end of the optoelectronic coupler is electrically connected to a first end of the third resistor and a first end of the first capacitor; and a second end of the third resistor and a second end of the first capacitor are both grounded; The optoelectronic coupler is used for disconnecting the third end and the fourth end of the optoelectronic coupler when the output voltage is less than the preset voltage.

6. The power supply circuit of claim 5, wherein, The coupling sub-circuit further comprises a first comparator; A first input terminal of the first comparator is electrically connected with an output terminal of the detection sub-circuit, a second input terminal of the first comparator is electrically connected with the preset voltage, and an output terminal of the first comparator is electrically connected with a first terminal of the optoelectronic coupler and / or a second terminal of the optoelectronic coupler; The first comparator is configured to compare the output voltage with the preset voltage. Alternatively, the coupling sub-circuit further comprises a third switch. A control terminal of the third switch is electrically connected with an output terminal of the detection sub-circuit, a first terminal of the third switch is electrically connected with a second terminal of the optoelectronic coupler, and a second terminal of the third switch is electrically connected with an equipotential point. The third switch is configured to disconnect the first terminal and the second terminal of the third switch when the output voltage is less than the preset voltage.

7. The power supply circuit of claim 4, wherein, The detection sub-circuit comprises a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a voltage stabilizing diode, a fourth switch, a fifth switch, and a second capacitor. A first terminal of the fourth resistor is electrically connected with an input terminal of the detection sub-circuit, a control terminal of the voltage stabilizing diode is electrically connected with a second terminal of the fourth resistor and a first terminal of the fifth resistor, a first terminal of the voltage stabilizing diode is electrically connected with a first terminal of the sixth resistor and a control terminal of the fourth switch, a first terminal of the fourth switch is electrically connected with a first terminal of the seventh resistor, a first terminal of the eighth resistor, and a control terminal of the fifth switch, a first terminal of the fifth switch is electrically connected with a first terminal of the ninth resistor, a second terminal of the sixth resistor, and a second terminal of the fourth switch are electrically connected with a high-level voltage, a second terminal of the seventh resistor, a second terminal of the ninth resistor, and a first terminal of the second capacitor are electrically connected with an output terminal of the detection sub-circuit, a second terminal of the fifth resistor, a second terminal of the voltage stabilizing diode, a second terminal of the eighth resistor, a second terminal of the fifth switch, and a second terminal of the second capacitor are electrically connected with an equipotential point. Alternatively, the detection sub-circuit comprises a second comparator, a sixth switch, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, and a third capacitor. A first terminal of the tenth resistor is electrically connected with an input terminal of the detection sub-circuit, a second terminal of the tenth resistor is electrically connected with a first input terminal of the second comparator and a first terminal of the eleventh resistor, a second input terminal of the second comparator is electrically connected with a reference voltage, an output terminal of the second comparator is electrically connected with a control terminal of the sixth switch and a first terminal of the twelfth resistor, a first terminal of the sixth switch is electrically connected with a first terminal of the thirteenth resistor, a second terminal of the thirteenth resistor is electrically connected with an input terminal of the coupling sub-circuit, a first terminal of the fourteenth resistor, and a first terminal of the third capacitor, a second terminal of the eleventh resistor, a second terminal of the twelfth resistor, a second terminal of the sixth switch, and a second terminal of the third capacitor are electrically connected with an equipotential point, and a second terminal of the fourteenth resistor is electrically connected with the reference voltage.

8. An electrical appliance, characterized in that The display screen comprises: a display screen; a power system electrically connected with the display screen, the power system being configured to drive the display screen to display a picture. a control system, electrically connected to the power system; The power supply circuit according to any one of claims 1-7, wherein an output end of the power supply circuit is connected to the control system, and the power supply circuit is configured to supply power to the control system.

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