Starting circuit and method of switching power supply circuit and household appliance

Abstract

The present application relates to a startup circuit, method, and household appliance for a switching power supply circuit. The startup circuit of the switching power supply circuit includes: a control unit, a self-excited oscillation circuit, and a delay circuit; wherein the control unit, as any one of a plurality of loads, is connected to the output end of the switching power supply circuit; the input end of the self-excited oscillation circuit is connected to the input end of the switching power supply circuit, and the output end of the self-excited oscillation circuit is connected to the pulse signal input end of the switching tube; the output end of the control unit is connected to the input end of the delay circuit, and the output end of the delay circuit is connected to the working state control end of the switching tube. In this way, the working state of the switching tube can be delayed by the delay circuit, thereby avoiding a large time delay in outputting the working voltage of other loads due to the output of the working voltage of the switching power supply circuit, thereby improving the performance and life of the household appliance.

Description

Technical Field

[0001] The present application relates to the technical field of switching power supplies, and in particular to a starting circuit, method, and household appliance of a switching power supply circuit. Background Art

[0002] As people's living standards continue to improve, household appliances such as refrigerators and air conditioners have become increasingly prevalent in their daily lives. To meet people's demands for performance and appearance of household appliances, switching power supply circuits are often used to power the power-consuming modules within the household appliances, such as chips and intelligent power modules (IPMs). When using switching power supply circuits to power the power-consuming modules within the household appliances, due to the differences in the operating voltages required by different power modules, this can lead to time differences in the establishment of the operating voltages for the different power modules, thereby affecting the performance and lifespan of the household appliances. For example, when using a switching power supply circuit to power the main chip and IPM within an air conditioner, since the main chip operates at 5V and the IPM operates at 15V, there will be a time difference between the generation of the 5V and 15V output voltages by the switching power supply circuit. After the 5V output voltage is generated, the generation of the 15V output voltage will be delayed, resulting in a long delay before the motor connected to the IPM can start. This, in turn, causes a long delay before the fan or other components connected to the motor start, significantly reducing the performance and lifespan of the household appliances.

[0003] Therefore, how to control the startup process of the switching power supply circuit so that the operating voltage creation time of different power modules is as close as possible has become a technical problem that needs to be solved urgently. Summary of the Invention

[0004] The present application provides a startup circuit, method, and household appliance for a switching power supply circuit to solve the problem in the prior art that a switching power supply circuit is used to create a time difference in the operating voltages of different power modules in a household appliance, thereby affecting the performance and life of the household appliance.

[0005] In a first aspect, the present application provides a startup circuit for a switching power supply circuit, the switching power supply circuit comprising a first inductor and a switching transistor, the switching transistor being configured to control a voltage value of a current flowing through the first inductor according to a received pulse signal, thereby controlling the switching power supply circuit to output multiple output voltages to power multiple loads, wherein the multiple output voltages have different voltage values; the startup circuit for the switching power supply circuit comprising: a control unit, a self-excited oscillation circuit, and a delay circuit;

[0006] Wherein, the control unit serves as any one of the multiple loads and is connected to the output end of the switching power supply circuit;

[0007] The input end of the self-excited oscillation circuit is connected to the input end of the switching power supply circuit, and the output end of the self-excited oscillation circuit is connected to the pulse signal input end of the switching tube. The self-excited oscillation circuit is used to generate a first pulse signal according to the voltage change of the input end of the switching power supply circuit, so that the switching tube controls the switching power supply circuit to output the operating voltage required by the control unit according to the first pulse signal;

[0008] The output end of the control unit is connected to the input end of the delay circuit, and the output end of the delay circuit is connected to the working state control end of the switching tube. The control unit is used to generate and output a second pulse signal when powered by the working voltage, and control the delay circuit to delay the working state of the switching tube through the second pulse signal.

[0009] Optionally, the self-excited oscillation circuit includes a current limiting resistor, a voltage regulator diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a first sliding resistor, a second sliding resistor, a first diode, a second diode, an operational amplifier and a first capacitor;

[0010] In which, the first end of the current-limiting resistor serves as the input end of the self-excited oscillation circuit and is connected to the input end of the switching power supply circuit. The second end of the current-limiting resistor is respectively connected to the first end of the second resistor and the positive electrode of the voltage-stabilizing diode. The second end of the second resistor is respectively connected to the non-inverting input end of the operational amplifier and the first end of the first resistor. The inverting input end of the operational amplifier is respectively connected to the first end of the first capacitor and the first end of the third resistor. The output end of the operational amplifier is connected to the first end of the fourth resistor. The second end of the third resistor is respectively connected to the cathode of the first diode and the anode of the second diode. The anode of the first diode is connected to the first end of the first sliding resistor, and the cathode of the second diode is connected to the first end of the second sliding resistor. The second ends of the first sliding resistor, the second ends of the second sliding resistor, the second ends of the fourth resistor, and the second end of the second resistor all serve as the output end of the self-excited oscillation circuit and are connected to the pulse signal input end of the switching tube. The negative electrode of the voltage-stabilizing diode, the second end of the first resistor, and the second end of the first capacitor are respectively connected to the ground end.

[0011] Optionally, the regulated voltage of the voltage regulator is less than or equal to the operating voltage of the operational amplifier.

[0012] Optionally, the period T and duty cycle D of the first pulse signal are respectively:

[0013]

[0014]

[0015] Among them, T represents the period of the first pulse signal, T1 represents the duration when the first pulse signal is at a high level, T2 represents the duration when the first pulse signal is at a low level, RW1 represents the resistance value of the first sliding resistor, RW2 represents the resistance value of the second sliding resistor, R1 represents the resistance value of the first resistor, R2 represents the resistance value of the second resistor, and R3 represents the resistance value of the third resistor.

[0016] Optionally, the delay circuit includes: a first transistor, a fifth resistor, a sixth resistor and a second capacitor;

[0017] Among them, the base of the first transistor is connected to the output end of the control unit as the input end of the delay circuit, the emitter of the first transistor is connected to the ground end, the collector of the first transistor is connected to the first end of the fifth resistor, the second end of the fifth resistor is respectively connected to the first end of the second capacitor, the first end of the sixth resistor and the gate of the switching tube, the second end of the second capacitor and the second end of the sixth resistor are both connected to the source of the switching tube, the drain of the switching tube is connected to the ground end, and the source of the switching tube and the gate of the switching tube together serve as the working state control end of the switching tube.

[0018] Optionally, the multiple loads further include an intelligent power module IPM; and the charging time of the second capacitor is greater than or equal to the time it takes for the output voltage of the switching power supply circuit to reach the operating voltage required by the intelligent power module IPM.

[0019] In a second aspect, the present application further provides a method for starting a switching power supply circuit, which is applied to the starting circuit of the switching power supply circuit according to any one of the first aspects, the method comprising:

[0020] The self-excited oscillation circuit generates a first pulse signal according to a voltage change at an input terminal of the switching power supply circuit;

[0021] The switch tube receives the first pulse signal and controls the switch power circuit to output the operating voltage required by the control unit according to the first pulse signal;

[0022] The control unit generates and outputs a second pulse signal when the operating voltage is supplied, and controls the delay circuit to perform delay control on the operating state of the switch tube through the second pulse signal.

[0023] Optionally, the control unit generates and outputs a second pulse signal when powered by the working voltage, including:

[0024] The control unit obtains voltage values corresponding to the multiple loads when the operating voltage is supplied, and the multiple loads include a control unit and an intelligent power module IPM;

[0025] According to the voltage values corresponding to the control unit and the intelligent power module IPM, the establishment status of the operating voltages of the control unit and the intelligent power module IPM is determined; when it is detected that the establishment of the operating voltage of the control unit is completed and the establishment of the operating voltage of the intelligent power module IPM is not completed, a second pulse signal is generated and output.

[0026] Optionally, the delay circuit includes: a first transistor, a fifth resistor, a sixth resistor, and a second capacitor; wherein the base of the first transistor is connected to the output of the control unit as the input of the delay circuit, the emitter of the first transistor is connected to the ground, the collector of the first transistor is connected to the first end of the fifth resistor, the second end of the fifth resistor is respectively connected to the first end of the second capacitor, the first end of the sixth resistor, and the gate of the switching tube, the second end of the second capacitor and the second end of the sixth resistor are both connected to the source of the switching tube, the drain of the switching tube is connected to the ground, and the source and the gate of the switching tube jointly serve as the working state control terminal of the switching tube;

[0027] The controlling the delay circuit to delay the working state of the switch tube by the second pulse signal includes:

[0028] The control unit obtains a voltage value of the gate of the first transistor, and determines whether the voltage value of the gate of the first transistor is greater than or equal to a preset threshold;

[0029] When the control unit determines that the voltage value of the gate of the first transistor is less than the preset threshold, the control unit outputs a high-level signal as the current signal of the second pulse signal, and the high-level signal is used to control the delay circuit to delay the working state of the switch tube;

[0030] When the control unit determines that the voltage value of the gate of the first transistor is greater than or equal to the preset threshold, a low-level signal is output as the current signal of the second pulse signal, and the low-level signal is used to disconnect the delay circuit to delay control the working state of the switching tube.

[0031] In a third aspect, the present application further provides a household appliance, which includes a switching power supply circuit, multiple loads, and a startup circuit of the switching power supply circuit as described in any one of the first aspects.

[0032] In an embodiment of the present application, the startup circuit of the switching power supply circuit includes: a control unit, a self-excited oscillation circuit and a delay circuit; wherein the control unit is connected to the output end of the switching power supply circuit as any one of a plurality of loads; the input end of the self-excited oscillation circuit is connected to the input end of the switching power supply circuit, and the output end of the self-excited oscillation circuit is connected to the pulse signal input end of the switching tube, and the self-excited oscillation circuit is used to generate a first pulse signal according to the voltage change of the input end of the switching power supply circuit, so that the switching tube controls the switching power supply circuit to output the working voltage required by the control unit according to the first pulse signal; the output end of the control unit is connected to the input end of the delay circuit, and the output end of the delay circuit is connected to the working state control end of the switching tube, and the control unit is used to generate and output a second pulse signal when the working voltage is supplied, and control the delay circuit to delay the working state of the switching tube through the second pulse signal. Through the startup circuit of the above-mentioned switching power supply circuit, when the switching power supply circuit has just been powered on but the control unit has not yet been powered on, the self-excited oscillation circuit can self-excite to generate a first pulse signal to the switching tube in the switching power supply circuit, and the switching tube controls the switching power supply circuit to output the working voltage required by the control unit, so that the control unit is powered on and works, and then the control unit outputs a second pulse signal to the delay circuit, and the delay circuit is controlled by the second pulse signal to delay control the working state of the switching tube, so that the output voltage of other channels of the switching power supply circuit reaches the working voltage of other loads and then resumes the working state, thereby avoiding a large time delay in the output of the working voltage of other loads by the switching power supply circuit due to the output of the working voltage of the control unit, thereby improving the performance and life of the household appliance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0035] Figure 1 A circuit diagram of a switching power supply circuit provided in an embodiment of the present application;

[0036] Figure 2 A schematic diagram of the structure of a startup circuit of a switching power supply circuit provided in an embodiment of the present application;

[0037] Figure 3A circuit diagram of a self-excited oscillation circuit provided in an embodiment of the present application;

[0038] Figure 4 A circuit diagram of a delay circuit provided in an embodiment of the present application;

[0039] Figure 5 A flowchart of a method for starting a switching power supply circuit provided in an embodiment of the present application;

[0040] Figure 6 A flowchart of another method for starting a switching power supply circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0041] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0042] See also Figure 1 , Figure 1 This is a circuit diagram of a switching power supply circuit provided in an embodiment of the present application. Figure 1 As shown, the switching power supply circuit 100 includes a first inductor L1 and a switching tube Q1. The switching tube Q1 is used to control the voltage value of the current flowing through the first inductor L1 according to the received pulse signal, so as to control the switching power supply circuit 100 to output multiple output voltages to power multiple loads. The voltage values of the multiple output voltages are different.

[0043] Specifically, the switching power supply circuit 100 may include a power factor correction (PFC) circuit and a flyback power supply circuit. The power factor correction circuit includes a first inductor L1, a switch Q1, and a diode D5, and the power factor correction circuit is a boost-type PFC circuit. The flyback power supply circuit includes a high-frequency transformer T1, rectifier diodes D6, D7, and D8, and filter capacitors C2, C3, and C4. In the switching power supply circuit 100, the inductor in the power factor correction circuit and the high-frequency transformer are combined into one. The first inductor L1 serves as the inductor in the power factor correction circuit and also as the primary side of the high-frequency transformer T1. The switch tube Q1 in the power factor correction circuit plays the same role as the switch tube in the flyback power supply circuit. The load in the switching power supply circuit 100 (i.e., the control unit 200) can be used to control the switch tube Q1, thereby eliminating the need for additional analog power integrated circuits (ICs) and inductors in the power factor correction circuit, effectively reducing hardware costs and reducing the area occupied by the printed circuit board (PCB). Figure 1 The high-frequency transformer T1 has three secondary sides, which respectively output different output voltages to load 1, load 2, and load 3. In an actual circuit, the number of loads in the switching power supply circuit 100 can be 2, 4, or another number, which is not specifically limited in this application.

[0044] See also Figure 2 , Figure 2 This is a schematic diagram of the structure of the startup circuit of the switching power supply circuit provided in the embodiment of the present application. Figure 2 As shown, the startup circuit of the switching power supply circuit includes: a control unit 200, a self-excited oscillation circuit 300 and a delay circuit 400;

[0045] The control unit 200 serves as any one of the multiple loads and is connected to the output end of the switching power supply circuit 100 ;

[0046] The input end of the self-oscillation circuit 300 is connected to the input end of the switching power supply circuit 100, and the output end of the self-oscillation circuit 300 is connected to the pulse signal input end of the switch tube Q1. The self-oscillation circuit 300 is used to generate a first pulse signal according to the voltage change at the input end of the switching power supply circuit 100, so that the switch tube Q1 controls the switching power supply circuit 100 to output the operating voltage required by the control unit 200 according to the first pulse signal;

[0047] The output end of the control unit 200 is connected to the input end of the delay circuit 400, and the output end of the delay circuit 400 is connected to the working state control end of the switch tube Q1. The control unit 200 is used to generate and output a second pulse signal when powered by the working voltage, and control the delay circuit 400 to delay the working state of the switch tube Q1 through the second pulse signal.

[0048] because Figure 1 In the illustrated switching power supply circuit 100, the inductance of the power factor correction circuit serves as the primary inductance of the transformer. When the switching power supply circuit 100 is connected to a power source, the control unit 200 is not yet powered and cannot output pulse information to control the switch Q1. Therefore, the self-oscillation circuit 300 is required to generate a pulse signal to control the switch Q1, so that the switch Q1 controls the switching power supply circuit 100 to provide the operating voltage required by the control unit 200. Therefore, in this embodiment, the self-oscillation circuit 300 first generates a first pulse signal and outputs this first pulse signal to the switch Q1 in the switching power supply circuit 100. The switch Q1 then controls the switching power supply circuit 100 to output the operating voltage required by the control unit 200 based on the first pulse signal. After the control unit 200 enters the working state with the working voltage supply, it generates and outputs a second pulse signal to the delay circuit 400. The second pulse signal controls the delay circuit 400 to delay the working state of the switch tube Q1, so that the output voltage of other channels of the switching power supply circuit 100 reaches the working voltage of other loads and then restores the working state of the switch tube Q1, thereby avoiding a large time delay in the output of the working voltage of other loads by the switching power supply circuit 100 due to the output of the working voltage of the control unit 200, thereby improving the performance and life of the household appliance.

[0049] Further, see Figure 3 , Figure 3 This is a circuit diagram of the self-excited oscillation circuit provided in the embodiment of the present application. Figure 3 As shown, the self-excited oscillation circuit 300 includes a current limiting resistor RZ, a voltage regulator diode DZ1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first sliding resistor RW1, a second sliding resistor RW2, a first diode D1, a second diode D2, an operational amplifier A and a first capacitor C1;

[0050] Among them, the first end of the current limiting resistor RZ serves as the input end of the self-excited oscillation circuit 300 and is connected to the input end of the switching power supply circuit 100. The second end of the current limiting resistor RZ is respectively connected to the first end of the second resistor R2 and the positive electrode of the voltage regulator tube DZ1. The second end of the second resistor R2 is respectively connected to the non-inverting input end of the operational amplifier A and the first end of the first resistor R1. The inverting input end of the operational amplifier A is respectively connected to the first end of the first capacitor C1 and the first end of the third resistor R3. The output end of the operational amplifier A is connected to the first end of the fourth resistor R4. The second end of the third resistor R3 is respectively connected to the first The cathode of the diode D1 and the anode of the second diode D2 are connected, the anode of the first diode D1 is connected to the first end of the first sliding resistor RW1, the cathode of the second diode D2 is connected to the first end of the second sliding resistor RW2, the second end of the first sliding resistor RW1, the second end of the second sliding resistor RW2, the second end of the fourth resistor R4 and the second end of the second resistor R2 all serve as the output end of the self-excited oscillation circuit 300, and are connected to the pulse signal input end of the switching tube Q1, the cathode of the voltage regulator tube DZ1, the second end of the first resistor R1 and the second end of the first capacitor C1 are respectively connected to the ground end.

[0051] It should be noted that the input end of the switching power supply circuit 100 is the end of the first inductor L1 that is closest to the input power supply. The voltage VR at this end is significantly lower than the voltage Vp at the end of the first inductor L1 that is further away from the input power supply. This helps reduce the power consumption of the current-limiting resistor RZ. Furthermore, when the input end of the switching power supply circuit 100 is connected to a power source, the voltage VR gradually rises until the voltage at the second end of the current-limiting resistor RZ reaches the regulated voltage of the voltage-limiting diode DZ1, whereupon it remains unchanged. The regulated voltage of the voltage-limiting diode DZ1 is then divided by the first resistor R1 and the second resistor R2 and connected to the non-inverting input of the operational amplifier A. This can be understood as the non-inverting input of the operational amplifier A inputting a high level, while the inverting input of the operational amplifier A inputting a low level. Consequently, the output of the operational amplifier A outputs a high level. This high level output can charge the first capacitor C1 through the fourth resistor R4, the first sliding resistor RW1, the first diode D1, and the third resistor R3. When the voltage of the charged first capacitor C1 exceeds the voltage of the non-inverting input of operational amplifier A, the output of operational amplifier A outputs a low level. At this time, the first capacitor C1 can be discharged through the third resistor R3, the second diode D2, and the second sliding resistor RW2. When the first capacitor C1 is discharged to a voltage lower than the voltage of the non-inverting input of operational amplifier A, the output of operational amplifier A outputs a high level. This cycle repeats, forming a first pulse signal of alternating high and low levels at the output of operational amplifier A. In this way, the charging and discharging process of the first capacitor C1 in the self-excited oscillation circuit 300 can cause the operational amplifier A to output high and low levels, thereby controlling the self-excited oscillation circuit 300 to output the first pulse signal.

[0052] Furthermore, the regulated voltage of the voltage regulator tube DZ1 is less than or equal to the operating voltage of the operational amplifier A. In this way, damage to the operational amplifier A caused by an excessively high regulated voltage of the voltage regulator tube DZ1 can be avoided.

[0053] Furthermore, the period T and duty cycle D of the first pulse signal are respectively:

[0054]

[0055]

[0056] Among them, T represents the period of the first pulse signal, T1 represents the duration when the first pulse signal is at a high level, T2 represents the duration when the first pulse signal is at a low level, RW1 represents the resistance value of the first sliding resistor RW1, RW2 represents the resistance value of the second sliding resistor RW2, R1 represents the resistance value of the first resistor R1, R2 represents the resistance value of the second resistor R2, and R3 represents the resistance value of the third resistor R3.

[0057] In this embodiment, when the output voltage UO of the operational amplifier A is at a high level, the output voltage UO charges the first capacitor C1 through the fourth resistor R4, the first sliding resistor RW1, the first diode D1, and the third resistor R3. Ignoring the equivalent resistance when the first diode D1 is turned on, the time constant τ1 is:

[0058] τ1=(RW1+R3)·C

[0059] When the output voltage UO of the operational amplifier A is low, the first capacitor C1 discharges through the third resistor R3, the second diode D2, and the second sliding resistor RW2 in sequence. Ignoring the equivalent resistance of the second diode D2 when it is turned on, the time constant τ2 is

[0060] τ2=(RW2+R3)·C

[0061] Combining the above two formulas, we can solve it using the three-element method of the first-order RC circuit:

[0062] The period T and duty cycle D of the first pulse signal are:

[0063]

[0064]

[0065] Among them, T represents the period of the first pulse signal, T1 represents the duration when the first pulse signal is at a high level, T2 represents the duration when the first pulse signal is at a low level, RW1 represents the resistance value of the first sliding resistor RW1, RW2 represents the resistance value of the second sliding resistor RW2, R1 represents the resistance value of the first resistor R1, R2 represents the resistance value of the second resistor R2, and R3 represents the resistance value of the third resistor R3.

[0066] That is to say, when designing the self-excited oscillation circuit 300, the period T and duty cycle D of the first pulse signal can be calculated based on the operating voltage required by the control unit 200, and then the resistance values of the first resistor R1, the second resistor R2, the third resistor R3, the first sliding resistor RW1, and the second sliding resistor RW2 can be set respectively using the above formula to satisfy the period T and duty cycle D.

[0067] See also Figure 4 , Figure 4 This is a circuit diagram of a delay circuit provided in an embodiment of the present application. Figure 4 As shown, the delay circuit 400 includes: a first transistor Q2, a fifth resistor R5, a sixth resistor R6 and a second capacitor C2;

[0068] Among them, the base of the first transistor Q2 serves as the input end of the delay circuit 400 and is connected to the output end of the control unit 200. The emitter of the first transistor Q2 is connected to the ground end. The collector of the first transistor Q2 is connected to the first end of the fifth resistor R5. The second end of the fifth resistor R5 is respectively connected to the first end of the second capacitor C2, the first end of the sixth resistor R6, and the gate of the switch tube Q1. The second end of the second capacitor C2 and the second end of the sixth resistor R6 are both connected to the source of the switch tube Q1. The drain of the switch tube Q1 is connected to the ground end. The source of the switch tube Q1 and the gate of the switch tube Q1 jointly serve as the working state control end of the switch tube Q1.

[0069] In one embodiment, when the control unit 200 is powered on, the control unit 200 can output a second pulse signal. At this time, the control unit 200 can detect the voltage value of the gate of the first transistor Q2. When the voltage value of the gate of the first transistor Q2 is less than a preset threshold value, a high-level signal is output. The high-level signal can control the first transistor Q2 to be turned on, and the input voltage VIN is powered on (i.e., a high voltage). At this time, the second capacitor C2 is charged through the fifth resistor R5, resulting in a high voltage across the fifth resistor R5. At this time, the voltage difference between the source and gate of the switch tube Q1 is less than the threshold voltage, and the switch tube Q1 is in the off state. When the second capacitor C2 is fully charged, the voltage across the fifth resistor R5 gradually decreases to 0. At this time, the voltage difference between the source and gate of the switch tube Q1 is greater than the threshold voltage, and the switch tube Q1 is in the on-off state. In this way, the switch tube Q1 can enter the working state. That is to say, the control unit 200 can output a high level of a preset duration, and realize the charging and discharging process of the second capacitor C2 through the high level, thereby realizing the delay function of the delay circuit 400; after the working voltage of other loads is established, the control unit 200 can output a low level signal to disconnect the delay circuit 400 from delaying the working state of the switch tube Q1. In this way, it is possible to effectively avoid the influence of the establishment of the working voltage of other loads after the switch tube Q1 is started. After the delay is performed by the delay circuit 400, the working voltage of other loads can be established at approximately the same time as the working voltage of the control unit 200, and then the control unit 200 and other loads such as IPM can be powered normally.

[0070] Furthermore, the multiple loads also include an intelligent power module IPM; the charging time of the second capacitor C2 is greater than or equal to the time it takes for the output voltage of the switching power supply circuit 100 to reach the operating voltage required by the intelligent power module IPM.

[0071] In one embodiment, the load of the switching power supply circuit 100 may include a control unit 200 and an intelligent power module (IPM). Since the operating voltage of the control unit 200 is typically 5V and the operating voltage of the intelligent power module (IPM) is typically 15V, there is a time difference between the creation of the 5V and 15V output voltages by the switching power supply circuit 100. Furthermore, the creation of the 15V output voltage is delayed after the creation of the 5V output voltage. This causes a long delay in starting the motor connected to the IPM, which in turn causes a long delay in starting the fan or other components connected to the motor. This significantly reduces the performance and lifespan of the household appliance. Therefore, in the delay circuit 400, by setting the parameters of the fifth resistor R5, the sixth resistor R6 and the second capacitor C2 in the delay circuit 400, the charging time of the second capacitor C2 can be greater than or equal to the time it takes for the output voltage of the switching power supply circuit 100 to reach the operating voltage required by the intelligent power module IPM. In this way, the switch tube Q1 can be turned off immediately after the switching power supply circuit 100 creates a 5V output voltage and creates a 15V output voltage. After the 5V output voltage is created, the working state of the switch tube Q1 can be restored.

[0072] In addition, see Figure 5 , Figure 5 This is a flow chart of a method for starting a switching power supply circuit according to an embodiment of the present application. Figure 5 As shown, the startup method of the switching power supply circuit is applied to the startup circuit of the switching power supply circuit in any of the above embodiments, and the method includes:

[0073] Step 501: The self-excited oscillation circuit generates a first pulse signal according to a voltage change at the input end of the switching power supply circuit, so that the switch tube controls the switching power supply circuit to output an operating voltage required by the control unit according to the first pulse signal.

[0074] Step 502: The control unit generates and outputs a second pulse signal when powered by the working voltage, and controls the delay circuit to delay the working state of the switch tube through the second pulse signal.

[0075] In one embodiment, a first pulse signal can be generated by a self-excited oscillation circuit and output to a switching transistor. The switching transistor then controls the switching power supply circuit to output the operating voltage required by the control unit based on the first pulse signal. After the control unit enters an operating state with the operating voltage, it generates and outputs a second pulse signal to a delay circuit. The delay circuit is controlled by the second pulse signal to delay control of the operating state of the switching transistor, so that the output voltage of other paths of the switching power supply circuit reaches the operating voltage of other loads before the switching transistor resumes its operating state. This avoids a significant delay in the switching power supply circuit outputting the operating voltage of other loads due to the output of the operating voltage of the control unit, thereby improving the performance and lifespan of the household appliance.

[0076] Furthermore, in step 502, the control unit generates and outputs a second pulse signal when powered by the working voltage, including:

[0077] The control unit obtains voltage values corresponding to multiple loads when powered by an operating voltage, and the multiple loads include the control unit and the intelligent power module IPM;

[0078] According to the voltage values corresponding to the control unit and the intelligent power module IPM, the establishment status of the operating voltage of the control unit and the intelligent power module IPM is determined; when it is detected that the establishment of the operating voltage of the control unit is completed and the operating voltage of the intelligent power module IPM is not completed, a second pulse signal is generated and output.

[0079] In one embodiment, the control unit can be connected to the two ends of multiple loads of the switching power supply circuit to collect the voltage value across each load, thereby determining the establishment status of the operating voltages of the multiple loads. For example, assuming the voltage value across the control unit reaches 5V, it indicates that the operating voltage of the control unit has been established; assuming the voltage value across the intelligent power module (IPM) is also 5V, it indicates that the operating voltage of the intelligent power module (IPM) has not been established. When the control unit detects that the operating voltage of the control unit has been established, but the operating voltage of the intelligent power module (IPM) has not been established, the control unit can generate and output a second pulse signal, which controls the delay circuit through the second pulse signal to delay control of the operating state of the switching tube.

[0080] Furthermore, the delay circuit includes: a first transistor, a fifth resistor, a sixth resistor, and a second capacitor; wherein the base of the first transistor is connected to the output end of the control unit as the input end of the delay circuit, the emitter of the first transistor is connected to the ground end, the collector of the first transistor is connected to the first end of the fifth resistor, the second end of the fifth resistor is respectively connected to the first end of the second capacitor, the first end of the sixth resistor, and the gate of the switching tube, the second end of the second capacitor and the second end of the sixth resistor are both connected to the source of the switching tube, the drain of the switching tube is connected to the ground end, and the source and the gate of the switching tube jointly serve as the working state control end of the switching tube;

[0081] The above step 502, controlling the delay circuit to delay the working state of the switch tube by using the second pulse signal, includes:

[0082] The control unit obtains a voltage value of the gate of the first transistor and determines whether the voltage value of the gate of the first transistor is greater than or equal to a preset threshold;

[0083] When the control unit determines that the voltage value of the gate of the first transistor is less than the preset threshold value, the control unit outputs a high-level signal as the current signal of the second pulse signal, and the high-level signal is used to control the delay circuit to delay the working state of the switch tube;

[0084] When the control unit determines that the voltage value of the gate of the first transistor is greater than or equal to the preset threshold, it outputs a low-level signal as the current signal of the second pulse signal. The low-level signal is used to disconnect the delay circuit to delay control the working state of the switching tube.

[0085] In one embodiment, the control unit can be connected to the gate of the first transistor and used to collect the voltage value of the gate of the first transistor and determine whether the voltage value of the gate of the first transistor is less than a preset threshold value. When the control unit determines that the voltage value of the gate of the first transistor is less than the preset threshold value, the control unit outputs a high-level signal as the current signal of the second pulse signal, and the high-level signal is used to control the delay circuit to delay the operating state of the switch tube. When the control unit determines that the voltage value of the gate of the first transistor is greater than or equal to the preset threshold value, the control unit outputs a low-level signal as the current signal of the second pulse signal, and the low-level signal is used to disconnect the delay circuit to delay the operating state of the switch tube. In this way, when it is detected that the operating voltage of the control unit has been established but the operating voltage of the intelligent power module (IPM) has not been established, a high-level signal can be output to control the delayed operation of the switch tube. When the operating voltages of both the control unit and the intelligent power module (IPM) have been established, a low-level signal is output to disable the delay circuit, thereby avoiding a large delay in the output of the operating voltage of other loads by the switching power supply circuit due to the output of the operating voltage of the control unit, thereby improving the performance and life of the household appliance.

[0086] In one embodiment, the implementation steps of the startup method of the switching power supply circuit are as follows: Figure 6 As shown, the starting method of the switching power supply circuit includes:

[0087] Step 601: Determine whether the operating voltage of the control unit is established.

[0088] If the operating voltage of the control unit has been established, step 602 is executed; if the operating voltage of the control unit has not been established, step 603 is executed.

[0089] Step 602: Determine whether the operating voltage of the IPM is established.

[0090] If the operating voltage of the IPM has been established, step 604 is executed; if the operating voltage of the IPM has not been established, step 605 is executed.

[0091] Step 603: Control the switch tube to continuously store energy in the primary inductance of the transformer in the switching power supply circuit, and the transformer performs power transmission.

[0092] Step 604: Turn on the subsequent circuits of the IPM.

[0093] Step 605: Generate and output a second pulse signal, and control the delay circuit to delay the working state of the switch tube through the second pulse signal.

[0094] Step 606: Determine whether the voltage value of the gate of the first transistor is greater than or equal to a preset threshold.

[0095] If the voltage value of the gate of the first transistor is less than the preset threshold, step 607 is executed; if the voltage value of the gate of the first transistor is greater than or equal to the preset threshold, step 608 is executed.

[0096] Step 607: output a high-level signal to control the delay circuit to perform delay control on the working state of the switch tube.

[0097] Step 608: Output a low level, disconnect the delay circuit and perform delay control on the working state of the switch tube.

[0098] In this way, the control unit can control the operation of the switch tube in the switching power supply circuit according to the collected voltage value of the load and the voltage value of the gate of the first transistor, thereby realizing the startup of the switching power supply circuit.

[0099] An embodiment of the present application further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the method for starting a switching power supply circuit provided in any of the aforementioned method embodiments are implemented.

[0100] An embodiment of the present application further provides a household appliance, which includes a switching power supply circuit, multiple loads, and a startup circuit of the switching power supply circuit provided by any one of the aforementioned embodiments.

[0101] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device that includes the element.

[0102] The foregoing is merely a detailed description of the present invention, intended to enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is to be construed in the widest manner consistent with the principles and novel features claimed herein.

Claims

1. A startup circuit for a switching power supply circuit, characterized in that: The switching power supply circuit includes a first inductor and a switching tube, wherein the switching tube is used to control the voltage value of the current flowing through the first inductor according to the received pulse signal, so as to control the switching power supply circuit to output multiple output voltages to power multiple loads, and the voltage values of the multiple output voltages are different; The startup circuit of the switching power supply circuit includes: a control unit, a self-excited oscillation circuit and a delay circuit; Wherein, the control unit serves as any one of the multiple loads and is connected to the output end of the switching power supply circuit; The input end of the self-excited oscillation circuit is connected to the input end of the switching power supply circuit, and the output end of the self-excited oscillation circuit is connected to the pulse signal input end of the switching tube. The self-excited oscillation circuit is used to generate a first pulse signal according to the voltage change of the input end of the switching power supply circuit, so that the switching tube controls the switching power supply circuit to output the operating voltage required by the control unit according to the first pulse signal; The output end of the control unit is connected to the input end of the delay circuit, and the output end of the delay circuit is connected to the working state control end of the switching tube. The control unit is used to generate and output a second pulse signal when powered by the working voltage, and control the delay circuit to delay the working state of the switching tube through the second pulse signal.

2. The startup circuit of the switching power supply circuit according to claim 1, characterized in that: The self-excited oscillation circuit includes a current limiting resistor, a voltage regulator, a first resistor, a second resistor, a third resistor, a fourth resistor, a first sliding resistor, a second sliding resistor, a first diode, a second diode, an operational amplifier and a first capacitor; In which, the first end of the current-limiting resistor serves as the input end of the self-excited oscillation circuit and is connected to the input end of the switching power supply circuit. The second end of the current-limiting resistor is respectively connected to the first end of the second resistor and the negative electrode of the voltage-stabilizing diode. The second end of the second resistor is respectively connected to the non-inverting input end of the operational amplifier and the first end of the first resistor. The inverting input end of the operational amplifier is respectively connected to the first end of the first capacitor and the first end of the third resistor. The output end of the operational amplifier is connected to the first end of the fourth resistor. The second end of the third resistor is respectively connected to the negative electrode of the first diode and the positive electrode of the second diode. The positive electrode of the first diode is connected to the first end of the first sliding resistor, and the negative electrode of the second diode is connected to the first end of the second sliding resistor. The second end of the first sliding resistor, the second end of the second sliding resistor, the second end of the fourth resistor, and the first end of the second resistor all serve as the output end of the self-excited oscillation circuit and are connected to the pulse signal input end of the switching tube. The positive electrode of the voltage-stabilizing diode, the second end of the first resistor, and the second end of the first capacitor are respectively connected to the ground end.

3. The startup circuit of the switching power supply circuit according to claim 2, characterized in that: The stabilizing voltage of the voltage regulator tube is less than or equal to the operating voltage of the operational amplifier.

4. The startup circuit of the switching power supply circuit according to claim 2, characterized in that: The period T and duty cycle D of the first pulse signal are respectively: Among them, T represents the period of the first pulse signal, T1 represents the duration when the first pulse signal is at a high level, T2 represents the duration when the first pulse signal is at a low level, RW1 represents the resistance value of the first sliding resistor, RW2 represents the resistance value of the second sliding resistor, R1 represents the resistance value of the first resistor, R2 represents the resistance value of the second resistor, and R3 represents the resistance value of the third resistor.

5. The startup circuit of the switching power supply circuit according to claim 1, characterized in that: The delay circuit includes: a first transistor, a fifth resistor, a sixth resistor and a second capacitor; Among them, the base of the first transistor is connected to the output end of the control unit as the input end of the delay circuit, the emitter of the first transistor is connected to the ground end, the collector of the first transistor is connected to the first end of the fifth resistor, the second end of the fifth resistor is respectively connected to the first end of the second capacitor, the first end of the sixth resistor and the gate of the switching tube, the second end of the second capacitor and the second end of the sixth resistor are both connected to the source of the switching tube, the drain of the switching tube is connected to the ground end, and the source of the switching tube and the gate of the switching tube together serve as the working state control end of the switching tube.

6. The startup circuit of the switching power supply circuit according to claim 5, characterized in that: The multiple loads further include an intelligent power module (IPM); and the charging time of the second capacitor is greater than or equal to the time it takes for the output voltage of the switching power supply circuit to reach the operating voltage required by the intelligent power module (IPM).

7. A method for starting a switching power supply circuit, characterized in that: The method applied to the startup circuit of the switching power supply circuit according to any one of claims 1 to 6 comprises: The self-excited oscillation circuit generates a first pulse signal according to a voltage change at an input terminal of the switching power supply circuit; The switch tube receives the first pulse signal and controls the switch power circuit to output the operating voltage required by the control unit according to the first pulse signal; The control unit generates and outputs a second pulse signal when the operating voltage is supplied, and controls the delay circuit to perform delay control on the operating state of the switch tube through the second pulse signal.

8. The method for starting a switching power supply circuit according to claim 7, wherein: The control unit generates and outputs a second pulse signal when the operating voltage is supplied, including: The control unit obtains voltage values corresponding to the multiple loads when the operating voltage is supplied, and the multiple loads include a control unit and an intelligent power module IPM; According to the voltage values corresponding to the control unit and the intelligent power module IPM, the establishment status of the operating voltages of the control unit and the intelligent power module IPM is determined; when it is detected that the establishment of the operating voltage of the control unit is completed and the establishment of the operating voltage of the intelligent power module IPM is not completed, a second pulse signal is generated and output.

9. The method for starting a switching power supply circuit according to claim 7, wherein: The delay circuit includes: a first transistor, a fifth resistor, a sixth resistor, and a second capacitor; wherein the base of the first transistor is connected to the output of the control unit as the input of the delay circuit, the emitter of the first transistor is connected to the ground, the collector of the first transistor is connected to the first end of the fifth resistor, the second end of the fifth resistor is connected to the first end of the second capacitor, the first end of the sixth resistor, and the gate of the switching transistor, respectively; the second end of the second capacitor and the second end of the sixth resistor are both connected to the source of the switching transistor, the drain of the switching transistor is connected to the ground, and the source and the gate of the switching transistor together serve as the working state control terminal of the switching transistor; The controlling the delay circuit to delay the working state of the switch tube by the second pulse signal includes: The control unit obtains a voltage value of the gate of the first transistor, and determines whether the voltage value of the gate of the first transistor is greater than or equal to a preset threshold; When the control unit determines that the voltage value of the gate of the first transistor is less than the preset threshold, the control unit outputs a high-level signal as the current signal of the second pulse signal, and the high-level signal is used to control the delay circuit to delay the working state of the switch tube; When the control unit determines that the voltage value of the gate of the first transistor is greater than or equal to the preset threshold, a low-level signal is output as the current signal of the second pulse signal, and the low-level signal is used to disconnect the delay circuit to delay control the working state of the switching tube.

10. A household appliance, characterized in that: The household appliance includes a switching power supply circuit, a plurality of loads, and a startup circuit of the switching power supply circuit according to any one of claims 1 to 6.

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