Load supply circuit and household appliance
By controlling the conduction of the thyristor during the positive and negative half-cycles of the AC power supply, the problem of thyristor damage due to heat inability to dissipate was solved, and safe operation of the thyristor was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHENZHEN H&T CONTROL TECH CO LTD
- Filing Date
- 2025-06-06
- Publication Date
- 2026-07-14
AI Technical Summary
In high-power heating scenarios, the junction temperature of the silicon controlled rectifier (SCR) may exceed the limit due to the inability to effectively dissipate heat, making it prone to damage.
A zero-crossing detection module and a control module are used to control the conduction timing of the thyristors, so that the first thyristor conducts during the positive half-cycle of the AC power supply and the second thyristor conducts during the negative half-cycle, thus sharing the heat generation power and forming a load power supply circuit.
By distributing the heat output evenly between the two thyristors, the risk of damage to the thyristors due to excessive heat is reduced.
Smart Images
Figure CN224503239U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of load power supply technology, and in particular to a load power supply circuit and a household appliance. Background Technology
[0002] The applications of thyristors in small household appliances are mainly concentrated in voltage regulation, speed control, and power control. For example, in devices such as electric fans, table lamps, and electric blankets, thyristors achieve stepless speed regulation or dimming by adjusting the conduction angle, replacing traditional mechanical switches and improving control accuracy and lifespan. In heating products such as rice cookers and electric kettles, thyristors control the on / off time and power of the heating element to maintain constant temperature or segmented heating. The advantages of thyristors are low cost and small size, but attention must be paid to the problem of thyristor overheating caused by conduction voltage drop. Currently, the overheating problem of thyristors is usually mitigated by heat sinks or optimized triggering circuits (such as zero-crossing triggering).
[0003] However, since a single thyristor is typically used to operate throughout the entire AC power cycle to achieve its function, heat dissipation through heat sinks or optimized triggering circuits (such as zero-crossing triggering) is ineffective in high-power heating scenarios. For example, the thermal resistance Rth(jc) of a TO-220 packaged thyristor is approximately 1.5℃ / W. This means that for every 1W of heat generated by the thyristor, the temperature difference between the junction temperature and the thyristor case is 1.5℃. A smaller Rth(jc) value indicates better heat dissipation. However, in scenarios involving high power consumption within a short period, the thyristor's power increases rapidly, and the heat cannot be dissipated, easily leading to excessive junction temperature and thermal damage. Utility Model Content
[0004] This application provides a load power supply circuit and a household appliance that can reduce the risk of damage to the silicon controlled rectifier (SCR).
[0005] In a first aspect, embodiments of this application provide a load power supply circuit, comprising: a zero-crossing detection module connected to an AC power supply and configured to output a zero-crossing detection signal based on the AC power supply, wherein the zero-crossing detection signal is at a first level when the voltage of the AC power supply is greater than zero, and at a second level when the voltage of the AC power supply is less than or equal to zero; and a control module connected to the zero-crossing detection module and configured to determine the zero point of the AC power supply based on the zero-crossing detection signal, and output a trigger signal according to the zero point of the AC power supply, wherein the timing at which the control module outputs the trigger signal is obtained by delaying the timing of a zero point in the AC power supply by a first duration, wherein the first duration is... The control module is configured to conduct in response to the trigger signal. A first thyristor is connected to the control module, the AC power supply, and the load, and is configured to conduct when the control module is on, the AC power supply is in its positive half-cycle, and the voltage of the AC power supply is greater than a first preset voltage value, to form a circuit where the AC power supply powers the load. A second thyristor is connected to the control module, the AC power supply, and the load, and is configured to conduct when the control module is on, the AC power supply is in its negative half-cycle, and the absolute value of the voltage of the AC power supply is greater than a second preset voltage value, to form a circuit where the AC power supply powers the load.
[0006] In one or more embodiments, the load power supply circuit further includes a first diode and a second diode; the anode of the first diode is connected to the control terminal of the first thyristor, the cathode of the first diode is connected to the switching module, the anode of the second diode is connected to the switching module, and the cathode of the second diode is connected to the load; wherein, when the switching module is turned on, and the AC power supply is in the positive half-cycle, and the voltage of the AC power supply is less than or equal to the first preset voltage value, the first diode and the second diode are forward-biased to generate a first current flowing through the first terminal of the non-control terminal of the first thyristor and the control terminal of the first thyristor; and when the switching module is turned on, and the AC power supply is in the positive half-cycle, and the voltage of the AC power supply is greater than the first preset voltage value, the first current triggers the first thyristor to turn on.
[0007] In one or more embodiments, the load power supply circuit further includes a first resistor; the first resistor is connected between the cathode of the first diode and the switching module.
[0008] In one or more embodiments, the load power supply circuit further includes a third diode and a fourth diode; the anode of the third diode is connected to the control terminal of the second thyristor, the cathode of the third diode is connected to the switching module, the anode of the fourth diode is connected to the switching module, and the cathode of the fourth diode is connected to the load; wherein, when the switching module is turned on, and the AC power supply is in the negative half-cycle, and the absolute value of the AC power supply voltage is less than or equal to the second preset voltage value, the third diode and the fourth diode are forward-biased to generate a second current flowing between the first terminal of the non-control terminal of the second thyristor and the control terminal of the second thyristor; and when the switching module is turned on, and the AC power supply is in the negative half-cycle, and the absolute value of the AC power supply voltage is greater than the second preset voltage value, the second current triggers the second thyristor to turn on.
[0009] In one or more embodiments, the load power supply circuit further includes a second resistor; the second resistor is connected between the control terminal of the second thyristor and the anode of the third diode.
[0010] In one or more embodiments, the switching module includes a first optocoupler; the anode of the light emitter of the first optocoupler is connected to a first voltage, the cathode of the light emitter of the first optocoupler is connected to the control module, a first end of the light receiver of the first optocoupler is connected to the first thyristor, and a second end of the light receiver of the first optocoupler is connected to the second thyristor; wherein, the first optocoupler is a bidirectional optocoupler.
[0011] In one or more embodiments, the switching module includes a third resistor connected between the cathode of the light emitter of the first optocoupler and the control module.
[0012] In one or more embodiments, the zero-crossing detection module includes a fourth resistor and a second optocoupler; the anode of the light emitter of the second optocoupler is connected to the live wire of the AC power supply, the cathode of the light emitter of the second optocoupler is connected to the neutral wire of the AC power supply, the first end of the light receiver of the second optocoupler is connected to the first end of the fourth resistor and the control module respectively, the second end of the fourth resistor is connected to a first voltage, and the second end of the light receiver of the second optocoupler is grounded.
[0013] In one or more embodiments, the zero-crossing detection module further includes a fifth resistor, a sixth resistor, a fifth diode, and a first capacitor; the fifth resistor is connected between the live wire of the AC power supply and the anode of the light emitter of the second optocoupler; the anode of the fifth diode is connected to the anode of the light emitter of the second optocoupler; the cathode of the fifth diode is connected to the cathode of the light emitter of the second optocoupler; the sixth resistor and the first capacitor are connected in series between the first terminal of the light receiver of the second optocoupler and ground; and the connection point between the sixth resistor and the first capacitor is connected to the control module.
[0014] Secondly, embodiments of this application provide a household appliance, including a load and a load power supply circuit as described above.
[0015] The beneficial effects of this application are as follows: The load power supply circuit of this application embodiment includes a zero-crossing detection module, a control module, a switching module, a first thyristor, and a second thyristor. The zero-crossing detection module outputs a zero-crossing detection signal based on the AC power supply. When the voltage of the AC power supply is greater than zero, the zero-crossing detection signal is at a first level; when the voltage of the AC power supply is less than or equal to zero, the zero-crossing detection signal is at a second level. When the AC power supply is in the positive half-cycle, the control module outputs a trigger signal after a first delay from the zero point at the beginning of the positive half-cycle, and the switching module is turned on. Subsequently, when the voltage of the AC power supply increases to a value greater than a first preset voltage value, the first thyristor is turned on, and the AC power supply supplies power to the load through the first thyristor. When the AC power supply is in the negative half-cycle, the control module outputs a trigger signal after a first delay from the zero point at the beginning of the negative half-cycle, and the switching module is turned on. Subsequently, when the absolute value of the AC power supply voltage increases to a value greater than a second preset voltage value, the second thyristor is turned on, and the AC power supply supplies power to the load through the second thyristor. It is evident that the first thyristor operates and bears the heat power only during the positive half-cycle of the AC power supply, while the second thyristor operates and bears the heat power only during the negative half-cycle of the AC power supply. Compared to related technologies, this is equivalent to distributing the heat power that one thyristor needs to bear equally among the two thyristors, which helps reduce the risk of the thyristor being damaged due to excessive heat. Attached Figure Description
[0016] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, which are not intended to limit the embodiments, and elements having the same reference numerals in the drawings are designated as similar elements.
[0017] Figure 1 This is a schematic diagram of the composition of the load power supply circuit provided in the embodiments of this application;
[0018] Figure 2 This is a schematic diagram of the circuit structure of the load power supply circuit provided in the embodiments of this application;
[0019] Figure 3 This is a schematic diagram of the AC power supply and trigger signal provided in an embodiment of this application;
[0020] Figure 4 This is a circuit diagram of the zero-crossing detection module provided in an embodiment of this application. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and thoroughly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.
[0022] It should be noted that when an element is described as "connected" to another element, it can be directly connected to the other element, or there can be one or more intermediate elements between them.
[0023] Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.
[0024] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the block diagram of the load power supply circuit provided in an embodiment of this application. Figure 1 As shown, the load power supply circuit 100 includes a zero-crossing detection module 10, a control module 20, a switching module 30, a first thyristor U1, and a second thyristor U2.
[0025] The zero-crossing detection module 10 is connected to the AC power supply 200. The control module 20 is connected to the zero-crossing detection module 10. The switch module 30 is connected to the control module 20. The first thyristor U1 is connected to the switch module 30, the AC power supply 200, and the load 300. The second thyristor U2 is connected to the switch module 30, the AC power supply 200, and the load 300.
[0026] Specifically, the zero-crossing detection module 10 is configured to output a zero-crossing detection signal based on the AC power supply 200. The zero-crossing detection signal is at a first level when the voltage of the AC power supply 200 is greater than zero, and at a second level when the voltage of the AC power supply 200 is less than or equal to zero. The first level and the second level are different levels. If the first level is high, the second level is low; if the second level is low, the second level is high.
[0027] The control module 20 is configured to determine the zero point of the AC power supply 200 based on the zero-crossing detection signal, and output a trigger signal according to the zero point of the AC power supply 200. The timing of the trigger signal output by the control module 20 is obtained by delaying the timing of a zero point in the AC power supply 200 by a first duration. The first duration is greater than or equal to zero. The first duration is a preset duration, which can be set based on the actual application scenario. This application embodiment does not impose specific limitations on this.
[0028] The switch module 30 is configured to turn on in response to a trigger signal.
[0029] The first thyristor U1 is configured to conduct when the switching module 30 is turned on, the AC power supply 200 is in the positive half-cycle, and the voltage of the AC power supply 200 is greater than a first preset voltage value, so as to form a circuit in which the AC power supply 200 supplies power to the load 300. The first preset voltage value is a pre-set voltage value, which can be set based on the actual application scenario. It only needs to meet the requirement that when the voltage of the AC power supply 200 is greater than the first preset voltage value, the current flowing through the first thyristor U1 can trigger the first thyristor U1 to conduct. The conduction of the first thyristor U1 corresponds to the connection between the first terminal and the second terminal of the non-control terminal of the first thyristor U1.
[0030] The second thyristor U2 is configured to conduct when the switching module 30 is turned on, the AC power supply 200 is in the negative half-cycle, and the absolute value of the voltage of the AC power supply 200 is greater than the second preset voltage value, so as to form a circuit for the AC power supply 200 to supply power to the load 300. The second preset voltage value is a pre-set voltage value, which can be set based on the actual application scenario. It only needs to meet the requirement that when the absolute value of the voltage of the AC power supply 200 is greater than the second preset voltage value, the current flowing through the second thyristor U2 can trigger the second thyristor U2 to conduct. The conduction of the second thyristor U2 corresponds to the connection between the first and second terminals of the non-control terminal of the second thyristor U2. The second preset voltage value and the first preset voltage value can be equal or unequal.
[0031] In practical applications, when the AC power supply 200 is in the positive half-cycle, the control module 20 outputs a trigger signal after a first time delay from the zero point at the beginning of the positive half-cycle, and the switch module 30 is turned on. Then, when the voltage of the AC power supply 200 increases to a value greater than the first preset voltage value, the first thyristor U1 is turned on, and the AC power supply 200 supplies power to the load 300 through the first thyristor U1.
[0032] When the AC power supply 200 is in the negative half-cycle, the control module 20 outputs a trigger signal after a first time delay from the zero point at the beginning of the negative half-cycle, and the switch module 30 is turned on. Then, when the absolute value of the voltage of the AC power supply 200 increases to a value greater than the second preset voltage value, the second thyristor U2 is turned on, and the AC power supply 200 supplies power to the load 300 through the second thyristor U2.
[0033] In summary, the first thyristor U1 operates and bears the heat power only during the positive half-cycle of the AC power supply 200, while the second thyristor U2 operates and bears the heat power only during the negative half-cycle of the AC power supply 200. Compared with related technologies, this is equivalent to distributing the heat power that one thyristor needs to bear equally among the two thyristors, which helps to reduce the risk of the thyristors being damaged due to excessive heat.
[0034] Please refer to Figure 2 , Figure 2 An exemplary circuit structure for a load power supply circuit is shown. For example... Figure 2 As shown, the load power supply circuit 100 also includes a first diode D1 and a second diode D2.
[0035] The anode of the first diode D1 is connected to the control terminal of the first thyristor U1, the cathode of the first diode D1 is connected to the switch module 30, the anode of the second diode D2 is connected to the switch module 30, and the cathode of the second diode D2 is connected to the load 300.
[0036] Specifically, when the switching module 30 is turned on, the AC power supply 200 is in the positive half-cycle, and the voltage of the AC power supply 200 is less than or equal to a first preset voltage value, the first diode D1 and the second diode D2 are forward-biased to generate a first current flowing between the first terminal of the non-control terminal of the first thyristor U1 and the control terminal of the first thyristor. Subsequently, the voltage of the AC power supply 200 gradually increases. When the voltage of the AC power supply 200 increases to a value greater than the first preset voltage, i.e., when the switching module 30 is turned on, the AC power supply 200 is in the positive half-cycle, and the voltage of the AC power supply 200 is greater than the first preset voltage value, the first current triggers the first thyristor U1 to turn on.
[0037] In some embodiments, the load power supply circuit 100 further includes a first resistor R1.
[0038] The first resistor R1 is connected between the cathode of the first diode D1 and the switching module 30. The first resistor R1 is a current-limiting resistor.
[0039] In some embodiments, the load power supply circuit 100 further includes a third diode D3 and a fourth diode D4.
[0040] The anode of the third diode D3 is connected to the control terminal of the second thyristor U2, the cathode of the third diode D3 is connected to the switch module 30, the anode of the fourth diode D4 is connected to the switch module 30, and the cathode of the fourth diode D4 is connected to the load 300.
[0041] Specifically, when the switch module 30 is turned on, the AC power supply 200 is in its negative half-cycle, and the absolute value of the AC power supply 200's voltage is less than or equal to a second preset voltage value, the third diode D3 and the fourth diode D4 are forward-biased to generate a second current flowing between the first terminal of the non-control terminal of the second thyristor U2 and the control terminal of the second thyristor U2. Subsequently, the absolute value of the AC power supply 200's voltage gradually increases. When the absolute value of the AC power supply 200's voltage increases to a level greater than the second preset voltage—that is, when the switch module 30 is turned on, the AC power supply 200 is in its negative half-cycle, and the absolute value of the AC power supply 200's voltage is greater than the second preset voltage value—the second current triggers the second thyristor U2 to turn on.
[0042] In some embodiments, the load power supply circuit 100 further includes a second resistor R2.
[0043] The second resistor R2 is connected between the control terminal of the second thyristor U2 and the anode of the third diode D3. The second resistor R2 is a current-limiting resistor.
[0044] In some embodiments, the switch module 30 includes a first optocoupler U3.
[0045] The anode of the light emitter of the first optocoupler U3 is connected to the first voltage V1, the cathode of the light emitter of the first optocoupler U3 is connected to the control module 20, the first end of the light receiver of the first optocoupler U3 is connected to the first thyristor U1, and the second end of the light receiver of the first optocoupler U3 is connected to the second thyristor U2. The first optocoupler U3 is a bidirectional optocoupler.
[0046] Specifically, when the control module 20 outputs a trigger signal (a low-level signal in this embodiment), the light emitter of the first optocoupler U3 emits light, the light receiver of the first optocoupler U3 is turned on, and the corresponding switch module 30 is turned on.
[0047] In some embodiments, the switching module 30 includes a third resistor R3.
[0048] The third resistor R3 is connected between the cathode of the light emitter of the first optocoupler U3 and the control module 20.
[0049] The following will combine Figure 3 The AC power supply and trigger signal pair shown Figure 2 The principle of the circuit structure shown will be explained.
[0050] Specifically, when the AC power supply 200 is in the positive half-cycle, the control module 20 outputs a trigger signal S1 after a first time delay from the zero point at the start of the positive half-cycle, and the switch module 30 is turned on. Among these, in... Figure 3In the implementation shown, the first duration is zero. That is, times T1, T2, T3, T4, T5, T6, and T7 are all zero points. At these times, a trigger signal S1 is output to the first optocoupler U3 to turn on the photodetector of the first optocoupler U3. The starting times of the positive half-cycle are times T1, T3, T5, and T7. At times T1, T3, T5, and T7, the first diode D1 and the second diode D2 are forward-biased. However, since the voltage of the AC power supply 200 is less than or equal to the first preset voltage value, only a first current is generated between the first terminal of the first thyristor U1 (non-control terminal) and the control terminal of the first thyristor U1. Afterward, the voltage of the AC power supply 200 gradually increases. When the voltage of the AC power supply 200 increases to a value greater than the first preset voltage, the first current triggers the first thyristor U1 to turn on, and the AC power supply 200 supplies power to the load 300 through the first thyristor U1.
[0051] When AC power supply 200 is in the negative half-cycle, control module 20 outputs a trigger signal after a first time delay from the zero point at the start of the negative half-cycle, and switch module 30 is turned on. The first time delay is zero, corresponding to the start times of the negative half-cycle as times T2, T4, and T6. That is, at times T2, T4, and T6, the third diode D3 and the fourth diode D4 are forward-biased. However, since the absolute value of the voltage of AC power supply 200 is less than or equal to the second preset voltage value, only a second current is generated between the first terminal of the non-control terminal of the second thyristor U2 and the control terminal of the second thyristor U2. Subsequently, the absolute value of the voltage of AC power supply 200 gradually increases. When the absolute value of the voltage of AC power supply 200 increases to greater than the second preset voltage, the second current triggers the second thyristor U2 to turn on, and AC power supply 200 supplies power to load 300 through the second thyristor U2.
[0052] In summary, the first thyristor U1 operates and bears the heat power only during the positive half-cycle of the AC power supply 200, while the second thyristor U2 operates and bears the heat power only during the negative half-cycle of the AC power supply 200. Compared with related technologies, this is equivalent to distributing the heat power that one thyristor needs to bear equally among the two thyristors, which helps to reduce the risk of the thyristors being damaged due to excessive heat.
[0053] Please refer to Figure 4 , Figure 4 An exemplary circuit structure of the zero-crossing detection module 10 is shown. For example... Figure 4 As shown, the zero-crossing detection module 10 includes a fourth resistor R4 and a second optocoupler U4.
[0054] The anode of the light emitter of the second optocoupler U4 is connected to the live wire of the AC power supply 200, the cathode of the light emitter of the second optocoupler U4 is connected to the neutral wire of the AC power supply 200, the first end of the light receiver of the second optocoupler U4 is connected to the first end of the fourth resistor R4 and the control module 20 respectively, the second end of the fourth resistor R4 is connected to the first voltage VA1, and the second end of the light receiver of the second optocoupler U4 is grounded to GND.
[0055] In some embodiments, the zero-crossing detection module 10 further includes a fifth resistor R5, a sixth resistor R6, a fifth diode D5, and a first capacitor C1.
[0056] The fifth resistor R5 is connected between the live wire of AC power supply 200 and the anode of the light emitter of the second optocoupler U4. The anode of the fifth diode D5 is connected to the anode of the light emitter of the second optocoupler U4, and the cathode of the fifth diode D5 is connected to the cathode of the light emitter of the second optocoupler U4. The sixth resistor R6 and the first capacitor C1 are connected in series between the first terminal of the light receiver of the second optocoupler U4 and ground GND. The connection point between the sixth resistor R6 and the first capacitor C1 is connected to the control module 20.
[0057] Specifically, when the AC power supply 200 is in the positive half-cycle, the light emitter of the second optocoupler U4 is energized, and the first terminal of the light receiver of the second optocoupler U4 (i.e., the fourth pin of the second optocoupler U4) is grounded to GND and pulled low, outputting the first level (which is low level at this time). When the AC power supply 200 is in the negative half-cycle, the AC power supply 200, the fifth diode D5, and the fifth resistor R5 form a circuit, the second optocoupler U4 is de-energized, and outputs the second level (which is high level at this time) based on the first voltage VA1.
[0058] This application also provides a household appliance, which includes a load and a load power supply circuit 100 in any embodiment of this application.
[0059] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.
[0060] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
Claims
1. A load power supply circuit, characterized in that, include: A zero-crossing detection module, connected to an AC power supply, is configured to output a zero-crossing detection signal based on the AC power supply, wherein the zero-crossing detection signal is at a first level when the voltage of the AC power supply is greater than zero, and at a second level when the voltage of the AC power supply is less than or equal to zero. A control module, connected to the zero-crossing detection module, is configured to determine the zero point of the AC power supply based on the zero-crossing detection signal, and output a trigger signal according to the zero point of the AC power supply. The timing at which the control module outputs the trigger signal is obtained by delaying the timing of a zero point in the AC power supply by a first duration, wherein the first duration is greater than or equal to zero. A switch module, connected to the control module, is configured to be turned on in response to the trigger signal; The first thyristor is connected to the switching module, the AC power supply and the load respectively, and is configured to conduct when the switching module is turned on, the AC power supply is in the positive half cycle and the voltage of the AC power supply is greater than a first preset voltage value, so as to form a circuit in which the AC power supply supplies power to the load. The second thyristor is connected to the switching module, the AC power supply, and the load, and is configured to conduct when the switching module is turned on, the AC power supply is in the negative half-cycle, and the absolute value of the voltage of the AC power supply is greater than a second preset voltage value, so as to form a circuit in which the AC power supply supplies power to the load.
2. The load power supply circuit according to claim 1, characterized in that, The load power supply circuit also includes a first diode and a second diode; The anode of the first diode is connected to the control terminal of the first thyristor, the cathode of the first diode is connected to the switching module, the anode of the second diode is connected to the switching module, and the cathode of the second diode is connected to the load. Specifically, when the switch module is turned on, the AC power supply is in the positive half-cycle, and the voltage of the AC power supply is less than or equal to the first preset voltage value, the first diode and the second diode are forward-biased to generate a first current flowing through the first terminal of the non-control terminal of the first thyristor and the control terminal of the first thyristor. When the switch module is turned on, the AC power supply is in the positive half-cycle, and the voltage of the AC power supply is greater than the first preset voltage value, the first current triggers the first thyristor to turn on.
3. The load power supply circuit according to claim 2, characterized in that, The load power supply circuit also includes a first resistor; The first resistor is connected between the cathode of the first diode and the switching module.
4. The load power supply circuit according to claim 1, characterized in that, The load power supply circuit also includes a third diode and a fourth diode; The anode of the third diode is connected to the control terminal of the second thyristor, the cathode of the third diode is connected to the switching module, the anode of the fourth diode is connected to the switching module, and the cathode of the fourth diode is connected to the load. Specifically, when the switch module is turned on, the AC power supply is in the negative half-cycle, and the absolute value of the AC power supply voltage is less than or equal to the second preset voltage value, the third diode and the fourth diode are forward-biased to generate a second current flowing between the first terminal of the non-control terminal of the second thyristor and the control terminal of the second thyristor. When the switch module is turned on, the AC power supply is in the negative half-cycle, and the absolute value of the AC power supply voltage is greater than the second preset voltage value, the second current triggers the second thyristor to turn on.
5. The load power supply circuit according to claim 4, characterized in that, The load power supply circuit also includes a second resistor; The second resistor is connected between the control terminal of the second thyristor and the anode of the third diode.
6. The load power supply circuit according to claim 1, characterized in that, The switching module includes a first optocoupler; The anode of the first optocoupler's light emitter is connected to a first voltage, the cathode of the first optocoupler's light emitter is connected to the control module, the first end of the first optocoupler's light receiver is connected to the first thyristor, and the second end of the first optocoupler's light receiver is connected to the second thyristor. The first optical coupler is a bidirectional optical coupler.
7. The load power supply circuit according to claim 6, characterized in that, The switching module includes a third resistor; The third resistor is connected between the cathode of the light emitter of the first optocoupler and the control module.
8. The load power supply circuit according to claim 1, characterized in that, The zero-crossing detection module includes a fourth resistor and a second optocoupler; The anode of the second optocoupler's light emitter is connected to the live wire of the AC power supply, the cathode of the second optocoupler's light emitter is connected to the neutral wire of the AC power supply, the first end of the second optocoupler's light receiver is connected to the first end of the fourth resistor and the control module, the second end of the fourth resistor is connected to the first voltage, and the second end of the second optocoupler's light receiver is grounded.
9. The load power supply circuit according to claim 8, characterized in that, The zero-crossing detection module also includes a fifth resistor, a sixth resistor, a fifth diode, and a first capacitor; The fifth resistor is connected between the live wire of the AC power supply and the anode of the light emitter of the second optocoupler. The anode of the fifth diode is connected to the anode of the light emitter of the second optocoupler. The cathode of the fifth diode is connected to the cathode of the light emitter of the second optocoupler. The sixth resistor and the first capacitor are connected in series between the first terminal of the light receiver of the second optocoupler and ground. The connection point between the sixth resistor and the first capacitor is connected to the control module.
10. A household appliance, characterized in that, Includes a load and a load power supply circuit as described in any one of claims 1 to 9.