Control circuit for reducing no-load power consumption and switching power supply

Abstract

The invention relates to a control circuit for reducing no-load power consumption and a switching power supply. The control circuit comprises a surge suppression module, a rectification module, a power conversion module and a switching control module, the surge suppression module comprises a thermistor and a relay; the surge suppression module, the rectifier module and the power conversion module are connected in sequence, and the switch control module is connected with the power conversion module; the power conversion module is used for generating a control signal; the switch control module is used for generating a driving signal according to the control signal and the reference signal, and controlling the on-off of the relay through the driving signal. When the power supply is in a light load or no load state, the power consumption is reduced, the standby power consumption requirement is met, the power supply damage can be reduced, and the power supply efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of switching power supply, more particularly, to a control circuit for reducing no-load power consumption and a switching power supply. BACKGROUND

[0002] In the starting process of the switching power supply, the inrush current is a phenomenon that cannot be ignored. It mainly occurs in the initial charging stage of the electrolytic capacitor. At this time, the input voltage is converted into direct current through the bridge rectifier after interference filtering. In this process, due to the need of the electrolytic capacitor to smooth the waveform, the current rises temporarily and sharply, forming an inrush current. Its size is affected by many factors, including the amplitude of the initial input voltage, the characteristics of the bridge rectifier, and the configuration of the electrolytic capacitor and the loop resistance. Especially when the AC input voltage reaches the peak value, starting the power supply will produce a peak input inrush current.

[0003] The current market switching power supply inrush current suppression method mainly has the following several kinds: the first kind: for medium and high power supply, mainly in series thermistor or a few ohm resistance, and in parallel with a relay, usually with auxiliary source power supply, VCC drive relay open. However, this method has high cost. The second kind: for medium and high power, no auxiliary source, no no-load power consumption requirement of power supply, through the series thermistor, and cooperate with parallel relay to realize. However, this method will quickly increase the power consumption of the whole machine, and cannot meet the power consumption requirement of ERP0.5W. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a control circuit for reducing no-load power consumption and a switching power supply to solve the problems in the prior art.

[0005] The technical scheme adopted by the present application to solve the technical problem is: a control circuit for reducing no-load power consumption is constructed, which comprises: a surge suppression module, a rectifier module, a power conversion module and a switch control module; the surge suppression module comprises: a thermistor and a relay connected in parallel with the thermistor;

[0006] The surge suppression module, the rectifier module and the power conversion module are connected in sequence, and the switch control module is connected with the power conversion module and the relay respectively;

[0007] The power conversion module is used for generating a control signal;

[0008] The switch control module is used for generating a drive signal according to the control signal and in combination with a reference signal, and controlling the on-off of the relay through the drive signal.

[0009] The power conversion module comprises a PFC module connected with the rectifier module and an LLC module connected with the PFC module.

[0010] The LLC module is configured to generate a first driving control signal when the power supply is in light load or no load.

[0011] The PFC module is configured to generate a second driving control signal when the power supply is in light load or no load.

[0012] The switch control module is configured to generate a driving signal according to the first driving control signal or the second driving control signal in combination with a reference signal.

[0013] The first driving control signal and the second driving control signal are intermittent PWM signals.

[0014] The control circuit for reducing no-load power consumption further comprises a voltage generation module.

[0015] The voltage generation module is configured to generate a power supply signal and provide the power supply signal to the PFC module, the LLC module and the switch control module.

[0016] The voltage generation circuit is further configured to generate a reference signal and provide the reference signal to the switch control module.

[0017] The switch control module comprises a signal sampling circuit, a voltage regulation circuit, a comparison circuit, a driving circuit and a switch control circuit.

[0018] An input end of the signal sampling circuit is connected with the PFC module or the LLC module, an output end of the signal sampling circuit is connected with a first input end of the comparison circuit, an input end of the voltage regulation circuit is connected with a second output end of the voltage generation module, an output end of the voltage regulation circuit is connected with a second input end of the comparison circuit, an output end of the comparison circuit is connected with an input end of the driving circuit, an output end of the driving circuit is connected with an input end of the switch control circuit, a power supply end of the switch control circuit is connected with a first output end of the voltage generation module, and an output end of the switch control circuit is connected with a power supply end of the relay.

[0019] The switch control module further comprises a back difference circuit.

[0020] The back difference circuit is connected with the comparison circuit in parallel.

[0021] In the control circuit for reducing no-load power consumption, the signal sampling circuit comprises a fourth diode, a fourth capacitor, a sixth resistor, a fourth resistor and a second capacitor.

[0022] An anode of the fourth diode is connected to the PFC module or the LLC module, a cathode of the fourth diode is connected to an input end of the fourth capacitor and an input end of the sixth resistor, an output end of the fourth capacitor is grounded, an output end of the sixth resistor is connected to an input end of the fourth resistor and a first input end of the comparison circuit, an output end of the fourth resistor is grounded, and the second capacitor is connected to the fourth resistor in parallel.

[0023] In the control circuit for reducing no-load power consumption, the voltage regulating circuit comprises a ninth resistor, a tenth resistor and a sixth capacitor.

[0024] An input end of the ninth resistor is connected to a second output end of the voltage generating module, an output end of the ninth resistor is connected to an input end of the tenth resistor and a second input end of the comparison circuit, an output end of the tenth resistor is grounded, and the sixth capacitor is connected to the tenth resistor in parallel.

[0025] In the control circuit for reducing no-load power consumption, the comparison circuit comprises a voltage comparator, the back difference circuit comprises a second resistor and a second diode, and the driving circuit comprises a seventh resistor, an eighth resistor and a fifth capacitor.

[0026] A positive input end of the voltage comparator is connected to an output end of the signal sampling circuit, a negative input end of the voltage comparator is connected to an output end of the voltage regulating module, an output end of the voltage comparator is connected to an input end of the seventh resistor, an output end of the seventh resistor is connected to an input end of the switch control circuit, a first end of the second resistor is connected to the positive input end of the voltage comparator, a second end of the second resistor is connected to a cathode of the second diode, an anode of the second diode is connected to the output end of the seventh resistor, an input end of the eighth resistor is connected to the output end of the seventh resistor, an output end of the eighth resistor is grounded, and the fifth capacitor is connected to the eighth resistor in parallel.

[0027] The positive input end of the voltage comparator is a first input end of the comparison circuit, and the negative input end of the voltage comparator is a second input end of the comparison circuit.

[0028] In the control circuit for reducing no-load power consumption, the switch control circuit comprises a fourth MOS transistor, a second triode, a third resistor, a fifth resistor, a first energy storage capacitor, a first resistor and a first diode.

[0029] The gate of the fourth MOS tube is connected with the output end of the driving circuit, the source of the fourth MOS tube is grounded, the drain of the fourth MOS tube is connected with the base of the second triode through the fifth resistor, the emitter of the second triode is connected with the first output end of the voltage generating module, the collector of the second triode is connected with the cathode of the first diode and the power supply end of the relay through the first resistor; the third resistor is connected between the emitter and the base of the second triode, the first end of the first energy storage capacitor is connected with the collector of the second triode, and the second end of the first energy storage capacitor is grounded; and the anode of the first diode is grounded.

[0030] The gate of the fourth MOS tube is the input end of the switch control circuit, the emitter of the second triode is the power supply end of the switch control circuit, and the connection end of the first resistor and the first diode is the output end of the switch control circuit.

[0031] The application further provides a switching power supply comprising the control circuit for reducing no-load power consumption.

[0032] The control circuit for reducing no-load power consumption and the switching power supply have the following beneficial effects: the switching power supply comprises a surge suppression module, a rectification module, a power conversion module and a switch control module; the surge suppression module comprises a thermistor and a relay; the surge suppression module, the rectification module and the power conversion module are sequentially connected, and the switch control module is connected with the power conversion module and the relay; the power conversion module is used for generating a control signal; the switch control module generates a driving signal according to the control signal and in combination with a reference signal, and controls the on-off of the relay through the driving signal. Through the application, the power consumption can be reduced when the power supply is in light load or no load, the standby power consumption requirement is met, the power supply damage is reduced, and the power supply efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0033] The application will be further described below in combination with the drawings and embodiments, and the drawings are as follows:

[0034] Figure 1 is a functional block diagram of the control circuit for reducing no-load power consumption provided by the embodiment of the application;

[0035] Figure 2 is a circuit principle diagram of the control circuit for reducing no-load power consumption provided by the embodiment of the application. DETAILED DESCRIPTION

[0036] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0037] The present application provides a control circuit for reducing no-load power consumption of a medium or high power supply. The control circuit for reducing no-load power consumption can meet the requirements of surge current and reduce no-load power consumption of the power supply without auxiliary source and under the requirement of no-load power consumption, meet the standby power consumption requirement of less than 0.5W, and reduce power supply loss and improve power supply efficiency.

[0038] Reference Figure 1 , Figure 1 A preferred example of the control circuit for reducing no-load power consumption provided by the present application is shown.

[0039] As Figure 1 shown, in this embodiment, the control circuit for reducing no-load power consumption includes a surge suppression module 10, a rectifier module 20, a power conversion module, and a switch control module 30. The surge suppression module 10 includes a thermistor RT1 and a relay connected in parallel with the thermistor RT1. The surge suppression module 10, the rectifier module 20, and the power conversion module are connected in sequence, and the switch control module 30 is connected with the power conversion module and the relay respectively. The power conversion module generates a control signal, which is sent to the switch control module 30. The switch control module 30 generates a drive signal according to the control signal and in combination with a reference signal, and controls the on-off of the relay through the drive signal.

[0040] Optionally, in the embodiment of the present application, the power conversion module includes a PFC module 40 connected with the rectifier module 20, and an LLC module 50 connected with the PFC module 40. In one embodiment, the control signal generated by the power conversion module can be a second drive control signal generated by the PFC module 40. Alternatively, in other embodiments, the control signal generated by the power conversion module can be a first drive control signal generated by the LLC module 50.

[0041] The LLC module 50 is used to generate a first drive control signal when the power supply is in light load or no load. The first drive control signal is an intermittent PWM signal. It should be noted that the intermittent PWM signal means that the LLC module 50 outputs the PWM signal in an intermittent manner when the power supply is in light load or no load.

[0042] In this embodiment of the invention, the PFC module 40 is used to generate a second drive control signal when the power supply is under light load or no load. This second drive control signal is an intermittent PWM signal. It should be noted that the intermittent PWM signal means that when the power supply is under light load or no load, the PFC module 40 outputs the PWM signal intermittently.

[0043] In this embodiment of the invention, the switch control module 30 is used to generate a drive signal based on a first drive control signal or a second drive control signal combined with a reference signal, and to control the on / off state of the relay through the drive signal.

[0044] Furthermore, such as Figure 1 As shown, the control circuit for reducing no-load power consumption also includes a voltage generation module 60. This voltage generation module 60 generates a power supply signal and provides it to the PFC module 40, LLC module 50, and switch control module 30. The voltage generation circuit also generates a reference signal and provides it to the switch control module 30. Specifically, the voltage generation can include two circuit parts: one part generates the power supply signal, and the other part generates the reference signal. The reference signal can be obtained by combining the main output auxiliary winding of the switching power supply with a step-down and voltage-regulating circuit. Alternatively, it can be obtained by step-down and voltage-regulating the VDD signal of the main chip in LLC module 50. The power supply signal can be obtained by rectifying the main power supply winding with a diode. The specific circuits for generating the power supply signal and the reference signal can refer to the conventional design of LED driver power supplies, and this invention does not impose specific limitations.

[0045] Specifically, by setting the switch control module 30, the first drive control signal or the second drive control signal can be compared with the reference signal to generate a corresponding drive signal, so that the relay is controlled to be turned off when the power supply is in a light load or no load state through the drive signal, so as to reduce the no load power consumption when the power supply is in a light load or no load state, and meet the standby power consumption requirement of less than 0.5W; and when the power output power reaches the set power, the relay is controlled to be turned on through the drive signal, so as to supply power to the rear stage circuit through the relay, avoiding the power supply power consumption rising caused by supplying power to the rear stage circuit through the thermistor RT1, so as to reduce the power loss and improve the power efficiency. The set power can be calculated and determined according to the power consumption of the thermistor RT1 and the efficiency of the power supply. The present application is not limited. The set power needs to consider the thermistor RT1 power consumption and the power supply efficiency, and cannot turn on the relay when no load. It should be noted that the first drive control signal and the second drive control signal adopt a two-choice mode, that is, the first drive control signal can be taken, or the second drive control signal can be taken. The first drive control signal is the lower MOS drive signal of the LLC module 50, and the second drive control signal is the MOS drive signal of the PFC.

[0046] Optionally, in the embodiment of the present application, the switch control module 30 comprises: a signal sampling circuit 301, a voltage regulating circuit 302, a comparison circuit 303, a drive circuit 305 and a switch control circuit 306. The input end of the signal sampling circuit 301 is connected with the PFC module 40 or the LLC module 50, the output end of the signal sampling circuit 301 is connected with the first input end of the comparison circuit 303, the input end of the voltage regulating circuit 302 is connected with the second output end of the voltage generating module 60, the output end of the voltage regulating circuit 302 is connected with the second input end of the comparison circuit 303, the output end of the comparison circuit 303 is connected with the input end of the drive circuit 305, the output end of the drive circuit 305 is connected with the input end of the switch control circuit 306, the power supply end of the switch control circuit 306 is connected with the first output end of the voltage generating module 60, and the output end of the switch control circuit 306 is connected with the power supply end of the relay. Further, as shown in the figure, the switch control module 30 further comprises a hysteresis circuit 304, and the hysteresis circuit 304 is connected with the comparison circuit 303 in parallel. Figure 1

[0047] ​Specifically, the signal sampling circuit 301 is configured to sample the first driving control signal or the second driving control signal. The signal sampling circuit 301 can collect the first driving control signal or the second driving control signal, and perform series voltage division on the first driving control signal or the second driving control signal to adjust the size of the peak voltage, and apply the collected sampling signal to the first input (positive terminal) of the comparison circuit 303. The voltage regulating circuit 302 is configured to perform voltage division on the reference signal to obtain a corresponding voltage division signal, and apply the voltage division signal to the second input (negative terminal) of the comparison circuit 303. The voltage regulating circuit 302 can be implemented by a series of resistors, and the series of resistors can perform series voltage division and have different resistance values to obtain different voltage division signals. The comparison circuit 303 is configured to compare the voltage at the positive terminal with the voltage at the negative terminal, and output a high-level signal or a low-level signal. The high-level signal or the low-level signal is applied to the driving circuit 305 to drive the hysteresis width of the switching control circuit 306, and the switching control circuit 306 is configured to control the working state of the relay. The hysteresis circuit 304 is configured to prevent the comparison circuit 303 from outputting high / low level oscillation, and ensure the stability and reliability of the relay control.

[0048] The application will be described in detail below with reference to a specific embodiment.

[0049] Reference Figure 2 , Figure 2 A preferred embodiment of the control circuit for reducing the no-load power consumption is shown.

[0050] As Figure 2 shown, in this embodiment, the rectification module 20 includes a rectification bridge BD1. The PFC module 40 includes a boost inductor L2A, a coupling inductor L2B, a third MOS tube Q3, a second energy storage capacitor CE2, a PFC control chip U6, and the third MOS tube Q3. The PFC module 40 is a CRM mode PFC scheme.

[0051] As Figure 2As shown, the first input end of the rectifier bridge BD1 is connected to the ACL end, the second input end of the rectifier bridge BD1 is connected to the ACN end through the thermistor RT1 (a positive temperature coefficient thermistor RT1), the output end of the rectifier bridge BD1 is connected to the anode of the third diode D3 through the boost inductor L2A, the cathode of the third diode D3 is connected to the input end of the second energy storage capacitor CE2, the output end of the second energy storage capacitor CE2 is grounded, and the input end of the second energy storage capacitor CE2 and the connection end of the cathode of the third diode D3 output the PFC voltage. The coupling inductor L2B is coupled with the boost inductor L2A, and the zero-crossing detection end of the PFC control chip U6 is connected with the coupling inductor L2B, the driving end of the PFC control chip U6 is connected to the gate of the third MOS tube Q3, the source of the third MOS tube Q3 is grounded, the drain of the third MOS tube Q3 is connected to the anode of the third diode D3, and the driving end of the PFC control chip U6 outputs the second driving control signal (PWM2).

[0052] The boost inductor L2A realizes the boost processing of the voltage to obtain the PFC voltage (V, that is, Vpfc). The coupling inductor L2B is a ZCD zero-current detection signal, mainly used for detecting the start time of the third MOS tube Q3. The third diode D3 is a boost diode, which is mainly used for isolating the voltage of the second energy storage capacitor CE2. The second energy storage capacitor CE2 is used to provide energy for the subsequent circuit when the third MOS tube Q3 is turned on and the boost inductor L2A stores energy, and the PFC control chip U6 is mainly used for performing PFC control.

[0053] As shown in Figure 2 The LLC module 50 includes a first MOS tube Q1, a fifth MOS tube Q5, an LLC control chip U7, an optoelectronic coupler OT1B, a seventh capacitor C7, and an input winding T2D. The drain of the first MOS tube Q1 is connected to the cathode of the third diode D3, the source of the first MOS tube Q1 is connected to the drain of the fifth MOS tube Q5, the gate of the first MOS tube Q1 is connected to the fourth pin of the LLC control chip U7, the source of the fifth MOS tube Q5 is grounded, the gate of the fifth MOS tube Q5 is connected to the fifth pin of the LLC control chip U7, the fifth pin of the LLC control chip U7 outputs the first driving control signal (PWM1), the seventh capacitor C7 and the input winding T2D are connected in series and then connected in parallel to the source and the drain of the fifth MOS tube Q5, and the optoelectronic coupler OT1B is connected between the first pin and the third pin of the LLC control chip U7. Among them, the first MOS tube Q1 and the fifth MOS tube Q5 are half-bridge power conversion MOS tubes, the seventh capacitor C7 is a resonance capacitor, the optoelectronic coupler OT1B receives a secondary feedback signal to control the output power, and the LLC control chip U7 performs LLC control.

[0054] As shown in Figure 2As shown, in this embodiment, the signal sampling circuit 301 includes: a fourth diode D4, a fourth capacitor C4, a sixth resistor R6, a fourth resistor R4, and a second capacitor C2. The anode of the fourth diode D4 is connected to the PFC module 40 or the LLC module 50, and the cathode of the fourth diode D4 is connected to the input terminals of the fourth capacitor C4 and the sixth resistor R6. The output terminal of the fourth capacitor C4 is grounded. The output terminal of the sixth resistor R6 is connected to the input terminal of the fourth resistor R4 and the first input terminal of the comparator circuit 303, and the output terminal of the fourth resistor R4 is grounded. The second capacitor C2 is connected in parallel with the fourth resistor R4. The fourth diode D4 prevents reverse voltage flow from the fourth capacitor C4, which could interfere with the power line drive signal. The fourth capacitor C4 is mainly used to store the energy of the first or second drive control signal. The sixth resistor R6 and the fourth resistor R4 form a series voltage divider relationship to adjust the magnitude of the sampling signal. Simultaneously, by assigning a reasonable value to the second capacitor C2, the drive control signal is sampled to obtain the corresponding sampling signal (Vb).

[0055] like Figure 2 As shown, in this embodiment, the voltage regulation circuit 302 includes a ninth resistor R9, a tenth resistor R10, and a sixth capacitor C6. The input terminal of the ninth resistor R9 is connected to the second output terminal of the voltage generation module 60, and the output terminal of the ninth resistor R9 is connected to the input terminal of the tenth resistor R10 and the second input terminal of the comparator circuit 303. The output terminal of the tenth resistor R10 is grounded, and the sixth capacitor C6 is connected in parallel with the tenth resistor R10. The reference signal is divided by the ninth resistor R9 and the tenth resistor R10 to obtain a voltage-divided signal (Va). Different Va values ​​can be obtained by adjusting the values ​​of the ninth resistor R9 or the tenth resistor R10.

[0056] like Figure 2As shown, in this embodiment, the comparison circuit 303 includes a voltage comparator U1; the hysteresis circuit 304 includes a second resistor R2 and a second diode D2; and the drive circuit 305 includes a seventh resistor R7, an eighth resistor R8, and a fifth capacitor C5. In this circuit, the positive input terminal of voltage comparator U1 is connected to the output terminal of signal sampling circuit 301, the negative input terminal of voltage comparator U1 is connected to the output terminal of voltage regulation module, the output terminal of voltage comparator U1 is connected to the input terminal of seventh resistor R7, and the output terminal of seventh resistor R7 is connected to the input terminal of switch control circuit 306; the first terminal of second resistor R2 is connected to the positive input terminal of voltage comparator U1, the second terminal of second resistor R2 is connected to the cathode of second diode D2, and the anode of second diode D2 is connected to the output terminal of seventh resistor R7; the input terminal of eighth resistor R8 is connected to the output terminal of seventh resistor R7, and the output terminal of eighth resistor R8 is grounded; fifth capacitor C5 is connected in parallel with eighth resistor R8; the positive input terminal of voltage comparator U1 is the first input terminal of comparator circuit 303, and the negative input terminal of voltage comparator U1 is the second input terminal of comparator circuit 303.

[0057] like Figure 2 As shown, Va and Vb are applied to the negative and positive terminals of voltage comparator U1, respectively. Voltage comparator U1 compares these two values ​​and determines whether the output of voltage comparator U1 is high or low based on their magnitudes. The circuit formed by the second resistor R2 and the second diode D2 mainly prevents the output of voltage comparator U1 from oscillating between high and low levels, ensuring the stability and reliability of the output signal of voltage comparator U1.

[0058] like Figure 2 As shown, in this embodiment, the switch control circuit 306 includes: a fourth MOSFET Q4, a second transistor Q2, a third resistor R3, a fifth resistor R5, a first energy storage capacitor CE1, a first resistor R1, and a first diode D1. In this circuit, the gate of the fourth MOSFET Q4 is connected to the output of the driving circuit 305, the source of the fourth MOSFET Q4 is grounded, the drain of the fourth MOSFET Q4 is connected to the base of the second transistor Q2 through the fifth resistor R5, the emitter of the second transistor Q2 is connected to the first output of the voltage generation module 60, and the collector of the second transistor Q2 is connected to the cathode of the first diode D1 and the power supply terminal of the relay through the first resistor R1; the third resistor R3 is connected between the emitter and base of the second transistor Q2; the first end of the first energy storage capacitor CE1 is connected to the collector of the second transistor Q2, and the second end of the first energy storage capacitor CE1 is grounded; the anode of the first diode D1 is grounded; the gate of the fourth MOSFET Q4 is the input of the switch control circuit 306, the emitter of the second transistor Q2 is the power supply terminal of the switch control circuit 306, and the connection between the first resistor R1 and the first diode D1 is the output of the switch control circuit 306.

[0059] Specifically, such asFigure 2 As shown, the seventh resistor R7, the eighth resistor R8, and the fifth capacitor C5 constitute the driving circuit 305 for the fourth MOSFET Q4. By adjusting the values ​​of the seventh resistor R7 and the eighth resistor R8, different driving signals (Vc) can be obtained. While Vc satisfies the driving of the fourth MOSFET Q4, it also acts on the second resistor R2 and the second diode D2, thereby adjusting the hysteresis width of the circuit (i.e., adjusting the time difference between the turn-on and turn-off of the fourth MOSFET Q4). The third resistor R3, the fifth resistor R5, the fourth MOSFET Q4, the second transistor Q2, the first energy storage capacitor CE1, the first resistor R1, and the first diode D1 constitute the relay's turn-on and turn-off control circuit. The third resistor R3 and the fifth resistor R5 form a voltage divider, providing the turn-on bias voltage to the second transistor Q2. The first energy storage capacitor CE1 stores energy to power the relay. The first resistor R1 is a current-limiting voltage divider resistor, ensuring the relay's power supply current. The first diode D1 is a reset diode, clamping the induced voltage in the relay winding when the relay is turned off, protecting the second transistor Q2 from damage.

[0060] Specifically, such as ​ As shown, the selection of the first drive control signal is used as an example for explanation. When the power supply is under light load or no load, the first drive control signal output by the PFC control chip U6 is acquired and stored through the fourth capacitor C4. After being divided by the sixth resistor R6 and the fourth resistor R4 in series, Vb is obtained. Vb is directly applied to the positive terminal of the voltage comparator U1. At the same time, the reference signal is divided by the ninth resistor R9 and the tenth resistor R10 to obtain Va. Va is directly applied to the negative terminal of the voltage comparator U1. The voltage comparator U1 compares Vb and Va and outputs a corresponding high-level signal or low-level signal according to the comparison result. This high-level signal or low-level signal is divided by the seventh resistor R7 and the eighth resistor R8 to obtain the drive signal Vc. This Vc is used to drive the fourth MOSFET Q4.

[0061] In light load or no-load conditions, the relay must be in the off state to meet the no-load power consumption requirement. Therefore, this invention can be designed so that the value of Vb is less than the value of Va in light load or no-load conditions. At this time, the voltage comparator U1 outputs a low-level signal, the fourth MOSFET Q4 is cut off, the second transistor Q2 is cut off, and the relay is disconnected because it is not energized (VCC1). As mentioned above, when all other parameters are determined, the power of the relay when it is turned on can be adjusted by adjusting the value of the tenth resistor R10. Therefore, based on this principle and considering both the power consumption of the thermistor RT1 and the efficiency of the power supply, this invention can control the relay to turn on when the power supply output power reaches the set power, thereby achieving both reduced no-load power consumption to meet the standby power consumption requirement of less than 0.5W and reduced losses (when the set power is reached, the relay is controlled to turn on. At this time, because the relay is turned on, the input voltage of the AC input terminal can be directly supplied to the subsequent circuit through the relay, greatly reducing the power consumption increase caused by the thermistor RT1) and improved power supply efficiency.

[0062] The present invention also provides a switching power supply, wherein the switching power supply may include the control circuit for reducing no-load power consumption disclosed in the embodiments of the present invention. Optionally, the switching power supply may be a medium-to-high power supply without an auxiliary source and with no-load power consumption requirements. For example, a medium-to-high power LED driver power supply without an auxiliary source and with no-load power consumption requirements.

[0063] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0064] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0065] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0066] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They do not limit the scope of protection of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A control circuit for reducing no-load power consumption, characterized in that, include: Surge suppression module, rectifier module, power conversion module, and switch control module; The surge suppression module includes: a thermistor and a relay connected in parallel with the thermistor; The surge suppression module, the rectifier module, and the power conversion module are connected in sequence, and the switch control module is connected to the power conversion module and the relay respectively. The power conversion module is used to generate control signals; The switch control module is used to generate a drive signal based on the control signal and a reference signal, and to control the on / off state of the relay through the drive signal.

2. The control circuit for reducing no-load power consumption according to claim 1, characterized in that, The power conversion module includes: a PFC module connected to the rectifier module, and an LLC module connected to the PFC module; The LLC module is used to generate a first drive control signal when the power supply is under light load or no load. The PFC module is used to generate a second drive control signal when the power supply is under light load or no load. The switch control module is used to generate a drive signal based on the first drive control signal or the second drive control signal and in combination with a reference signal; The first drive control signal and the second drive control signal are intermittent PWM signals.

3. The control circuit for reducing no-load power consumption according to claim 2, characterized in that, Also includes: Voltage generation module; The voltage generation module is used to generate a power supply signal and provide the power supply signal to the PFC module, the LLC module and the switch control module; The voltage generation circuit is also used to generate a reference signal and provide the reference signal to the switch control module.

4. The control circuit for reducing no-load power consumption according to claim 3, characterized in that, The switch control module includes: a signal sampling circuit, a voltage regulation circuit, a comparison circuit, a drive circuit, and a switch control circuit; The input terminal of the signal sampling circuit is connected to the PFC module or the LLC module, the output terminal of the signal sampling circuit is connected to the first input terminal of the comparator circuit, the input terminal of the voltage regulation circuit is connected to the second output terminal of the voltage generation module, the output terminal of the voltage regulation circuit is connected to the second input terminal of the comparator circuit, the output terminal of the comparator circuit is connected to the input terminal of the drive circuit, the output terminal of the drive circuit is connected to the input terminal of the switch control circuit, the power supply terminal of the switch control circuit is connected to the first output terminal of the voltage generation module, and the output terminal of the switch control circuit is connected to the power supply terminal of the relay.

5. The control circuit for reducing no-load power consumption according to claim 4, characterized in that, The switch control module further includes: a hysteresis circuit; The hysteresis circuit is connected in parallel with the comparator circuit.

6. The control circuit for reducing no-load power consumption according to claim 5, characterized in that, The signal sampling circuit includes: a fourth diode, a fourth capacitor, a sixth resistor, a fourth resistor, and a second capacitor; The anode of the fourth diode is connected to the PFC module or LLC module, the cathode of the fourth diode is connected to the input terminal of the fourth capacitor and the input terminal of the sixth resistor, the output terminal of the fourth capacitor is grounded, the output terminal of the sixth resistor is connected to the input terminal of the fourth resistor and the first input terminal of the comparator circuit, the output terminal of the fourth resistor is grounded, and the second capacitor is connected in parallel with the fourth resistor.

7. The control circuit for reducing no-load power consumption according to claim 5, characterized in that, The voltage regulation circuit includes: a ninth resistor, a tenth resistor, and a sixth capacitor; The input terminal of the ninth resistor is connected to the second output terminal of the voltage generation module, the output terminal of the ninth resistor is connected to the input terminal of the tenth resistor and the second input terminal of the comparator circuit, the output terminal of the tenth resistor is grounded, and the sixth capacitor is connected in parallel with the tenth resistor.

8. The control circuit for reducing no-load power consumption according to claim 5, characterized in that, The comparison circuit includes a voltage comparator; the hysteresis circuit includes a second resistor and a second diode; the drive circuit includes a seventh resistor, an eighth resistor, and a fifth capacitor. The positive input terminal of the voltage comparator is connected to the output terminal of the signal sampling circuit, the negative input terminal of the voltage comparator is connected to the output terminal of the voltage regulation module, the output terminal of the voltage comparator is connected to the input terminal of the seventh resistor, and the output terminal of the seventh resistor is connected to the input terminal of the switch control circuit; the first terminal of the second resistor is connected to the positive input terminal of the voltage comparator, the second terminal of the second resistor is connected to the cathode of the second diode, and the anode of the second diode is connected to the output terminal of the seventh resistor; the input terminal of the eighth resistor is connected to the output terminal of the seventh resistor, the output terminal of the eighth resistor is grounded, and the fifth capacitor is connected in parallel with the eighth resistor; The positive input terminal of the voltage comparator is the first input terminal of the comparison circuit, and the negative input terminal of the voltage comparator is the second input terminal of the comparison circuit.

9. The control circuit for reducing no-load power consumption according to claim 4, characterized in that, The switching control circuit includes: a fourth MOSFET, a second transistor, a third resistor, a fifth resistor, a first energy storage capacitor, a first resistor, and a first diode; The gate of the fourth MOSFET is connected to the output terminal of the driving circuit, the source of the fourth MOSFET is grounded, the drain of the fourth MOSFET is connected to the base of the second transistor through the fifth resistor, the emitter of the second transistor is connected to the first output terminal of the voltage generation module, and the collector of the second transistor is connected to the cathode of the first diode and the power supply terminal of the relay through the first resistor; the third resistor is connected between the emitter and base of the second transistor, the first terminal of the first energy storage capacitor is connected to the collector of the second transistor, and the second terminal of the first energy storage capacitor is grounded; the anode of the first diode is grounded. The gate of the fourth MOS transistor is the input terminal of the switch control circuit, the emitter of the second transistor is the power supply terminal of the switch control circuit, and the connection terminal of the first resistor and the first diode is the output terminal of the switch control circuit.

10. A switching power supply, characterized in that, include: The control circuit for reducing no-load power consumption according to any one of claims 1-9.

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