Switch driving circuit, method and switch circuit

Abstract

The present invention discloses a switch drive circuit, method and switch circuit. A front-stage zero-crossing detection circuit detects the zero-crossing point of the signal waveform input by a relay and generates a first zero-crossing detection signal; a rear-stage zero-crossing detection circuit detects the zero-crossing point of the signal waveform output by the relay and generates a second zero-crossing detection signal; a control circuit determines the delayed drive time or the advanced drive time of the relay based on the comparison result of the first zero-crossing detection signal and the second zero-crossing detection signal, and adjusts the next drive time of the relay based on the delayed drive time or the advanced drive time to drive the relay at the zero-crossing point. It can be seen that the present application can adaptively adjust the drive control time of the relay according to the actual action time of the relay to achieve the control purpose of driving the relay at the zero-crossing point, thereby avoiding the failure of the zero-crossing detection effect and playing an effective role in protecting circuit components.

Description

Technical Field

[0001] The present invention relates to the field of intelligent switch applications, and in particular to a switch driving circuit, method, and switch circuit. Background Art

[0002] Currently, to prevent relays in switching circuits from burning out or damaging other circuit components due to excessive instantaneous starting current, the principle of zero-crossing detection is often used to ensure that the relays in the switching circuits operate at the current zero crossing, effectively protecting the circuit components. Specifically, the zero-crossing detection principle of the switching circuit is as follows: before each relay operation, the zero-crossing time of the current waveform input to the relay is detected in the current cycle. Based on the zero-crossing time of the current waveform and its waveform cycle time, the zero-crossing drive time of the relay in the next cycle is determined, thereby ensuring that the relay operates at the current zero crossing.

[0003] However, there are physical differences between different relays, even between relays in the same batch, which leads to different actuation times for the same zero-crossing drive time. That is, there may be three zero-crossing detection drive results for the relay: the relay actuates accurately at the current zero crossing; the relay actuates with a delay; and the relay actuates in advance. However, both delayed and early actuation of the relay will cause the zero-crossing detection effect to fail, and it cannot effectively protect the circuit components.

[0004] Therefore, how to provide a solution to the above technical problems is a problem that technicians in this field currently need to solve. Summary of the Invention

[0005] The object of the present invention is to provide a switch driving circuit, method and switch circuit, which can adaptively adjust the driving control time of the relay according to the actual operation time of the relay, so as to achieve the control purpose of driving the relay at the zero crossing point, thereby avoiding the failure of the zero crossing detection effect and playing an effective role in protecting circuit components.

[0006] To solve the above technical problems, the present invention provides a switch driving circuit, which is applied to a switch circuit including a relay, comprising:

[0007] A front-stage zero-crossing detection circuit connected to the input end of the relay is used to detect the zero-crossing point of the signal waveform input by the relay and generate a first zero-crossing detection signal;

[0008] A subsequent zero-crossing detection circuit connected to the output end of the relay, for detecting a zero-crossing point of a signal waveform output by the relay and generating a second zero-crossing detection signal;

[0009] The control circuits are respectively connected to the front-stage zero-crossing detection circuit and the rear-stage zero-crossing detection circuit, and are used to determine the delayed driving time or the advanced driving time of the relay according to the comparison result of the first zero-crossing detection signal and the second zero-crossing detection signal, and adjust the next driving time of the relay according to the delayed driving time or the advanced driving time to drive the relay at the zero crossing point.

[0010] Preferably, the front-stage zero-crossing detection circuit includes a first resistor, a second resistor, a first diode, a second diode, a third diode, a fourth diode and a photoelectric coupler; the photoelectric coupler includes a light-emitting diode and an optocoupler transistor; wherein:

[0011] The positive end of the input waveform of the relay is connected to the first end of the first resistor, the second end of the first resistor is respectively connected to the cathode of the first diode and the anode of the second diode, the negative end of the input waveform of the relay is respectively connected to the cathode of the third diode and the anode of the fourth diode, the anode of the light-emitting diode is respectively connected to the anode of the first diode and the anode of the third diode, the cathode of the light-emitting diode is respectively connected to the cathode of the second diode and the cathode of the fourth diode, the collector of the optocoupler is connected to a preset DC voltage, the emitter of the optocoupler is connected to the first end of the second resistor and the common end is connected to the control circuit, and the second end of the second resistor is grounded.

[0012] Preferably, the structure of the rear-stage zero-crossing detection circuit is the same as that of the front-stage zero-crossing detection circuit.

[0013] Preferably, the control circuit is specifically configured to, after the relay is actuated, determine that the relay is actuated in advance if the second zero-crossing detection signal already has a detection pulse signal before the zero-point start time corresponding to the first zero-crossing detection signal, and adjust the next driving time of the relay according to T=T+(T0-T1) to drive the relay at the zero-crossing point;

[0014] Among them, T is the driving time setting value of the relay; T0 is the zero point starting time corresponding to the front-stage zero-crossing detection circuit after the relay is actuated; T1 is the zero point starting time corresponding to the rear-stage zero-crossing detection circuit after the relay is actuated.

[0015] Preferably, the control circuit is specifically configured to, after the relay is actuated, determine that the relay is delayed in actuation if the second zero-crossing detection signal has a detection pulse signal some time after the zero-point start time corresponding to the first zero-crossing detection signal, and adjust the next driving time of the relay according to T=T-(T2-T0) so as to drive the relay at the zero-crossing point;

[0016] Among them, T is the driving time setting value of the relay; T0 is the zero point starting time corresponding to the front-stage zero-crossing detection circuit after the relay is actuated; T2 is the zero point starting time corresponding to the rear-stage zero-crossing detection circuit after the relay is actuated.

[0017] Preferably, the control circuit is further configured to, after the relay is actuated, determine that the relay is actuated at the zero-crossing point if the zero-point start times corresponding to the first zero-crossing detection signal and the second zero-crossing detection signal are consistent.

[0018] To solve the above technical problems, the present invention further provides a switch driving method, which is applied to any of the above switch driving circuits, comprising:

[0019] The front-stage zero-crossing detection circuit detects the zero-crossing point of the signal waveform input by the relay and generates a first zero-crossing detection signal;

[0020] The post-stage zero-crossing detection circuit detects the zero-crossing point of the signal waveform output by the relay and generates a second zero-crossing detection signal;

[0021] The control circuit determines the delayed driving time or the advanced driving time of the relay according to the comparison result of the first zero-crossing detection signal and the second zero-crossing detection signal, and adjusts the next driving time of the relay according to the delayed driving time or the advanced driving time to drive the relay at the zero-crossing point.

[0022] In order to solve the above technical problems, the present invention further provides a switching circuit, including a relay and any one of the above switch driving circuits.

[0023] The present invention provides a switch drive circuit, comprising a front-stage zero-crossing detection circuit, a rear-stage zero-crossing detection circuit, and a control circuit. The front-stage zero-crossing detection circuit detects the zero-crossing point of the signal waveform input by the relay and generates a first zero-crossing detection signal; the rear-stage zero-crossing detection circuit detects the zero-crossing point of the signal waveform output by the relay and generates a second zero-crossing detection signal; the control circuit determines the delayed drive time or the advanced drive time of the relay based on the comparison result of the first zero-crossing detection signal and the second zero-crossing detection signal, and adjusts the next drive time of the relay based on the delayed drive time or the advanced drive time to drive the relay at the zero-crossing point. It can be seen that the present application can adaptively adjust the drive control time of the relay according to the actual action time of the relay to achieve the control purpose of driving the relay at the zero-crossing point, thereby avoiding the failure of the zero-crossing detection effect and playing an effective role in protecting circuit components.

[0024] The present invention also provides a switch driving method and a switch circuit, which have the same beneficial effects as the above switch driving circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the prior art and the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 A schematic structural diagram of a switch driving circuit provided by an embodiment of the present invention;

[0027] Figure 2 A schematic structural diagram of a front-stage zero-crossing detection circuit provided by an embodiment of the present invention;

[0028] Figure 3 A comparison diagram of the zero-crossing detection signals of the front and rear stages when a relay provided by an embodiment of the present invention operates at a zero-crossing point;

[0029] Figure 4 A comparison diagram of the zero-crossing detection signals of the front and rear stages when the relay is actuated in advance is provided in an embodiment of the present invention;

[0030] Figure 5 A comparison diagram of the zero-crossing detection signals of the front and rear stages when the relay is delayed in action is provided in an embodiment of the present invention;

[0031] Figure 6 A flow chart of a switch driving method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The core of the present invention is to provide a switch driving circuit, method and switch circuit, which can adaptively adjust the driving control time of the relay according to the actual action time of the relay to achieve the control purpose of driving the relay at the zero crossing point, thereby avoiding the failure of the zero crossing detection effect and playing an effective role in protecting circuit components.

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0034] Please refer to Figure 1 , Figure 1 A schematic structural diagram of a switch driving circuit provided by an embodiment of the present invention.

[0035] The switch drive circuit is applied to a switch circuit including a relay, including:

[0036] A front-stage zero-crossing detection circuit 1 connected to the input terminal of the relay is used to detect the zero-crossing point of the signal waveform input by the relay and generate a first zero-crossing detection signal;

[0037] A subsequent zero-crossing detection circuit 2 connected to the output terminal of the relay is used to detect the zero-crossing point of the signal waveform output by the relay and generate a second zero-crossing detection signal;

[0038] The control circuit 3 is connected to the front-stage zero-crossing detection circuit 1 and the rear-stage zero-crossing detection circuit 2, respectively, and is used to determine the delayed driving time or the advanced driving time of the relay according to the comparison result of the first zero-crossing detection signal and the second zero-crossing detection signal, and adjust the next driving time of the relay according to the delayed driving time or the advanced driving time to drive the relay at the zero crossing point.

[0039] Specifically, the switch driving circuit of the present application includes a front-stage zero-crossing detection circuit 1, a rear-stage zero-crossing detection circuit 2 and a control circuit 3, and its working principle is as follows:

[0040] After receiving the periodically changing signal waveform input by the relay, the front-stage zero-crossing detection circuit 1 can detect the zero-crossing point of the signal waveform input by the relay and generate a first zero-crossing detection signal to the control circuit 3. Similarly, after the relay is turned on, the rear-stage zero-crossing detection circuit 2 can receive the signal waveform output by the relay and detect the zero-crossing point of the signal waveform output by the relay, generating a second zero-crossing detection signal to the control circuit 3.

[0041] It can be understood that under different action conditions of the relay (accurate action / delayed action / early action at the current zero crossing), the signal comparison conditions of the first zero-crossing detection signal and the second zero-crossing detection signal are different, so the control circuit 3 of the present application can determine the actual action condition of the relay based on the comparison result of the first zero-crossing detection signal and the second zero-crossing detection signal, and when the relay is delayed in action, the delayed driving time of the relay is determined according to the comparison result of the first zero-crossing detection signal and the second zero-crossing detection signal, with the purpose of adjusting the next driving time of the relay according to the delayed driving time of the relay, so as to achieve driving the relay at the current zero crossing point when the relay is driven next time; similarly, when the relay is acted in advance, the advance driving time of the relay is determined according to the comparison result of the first zero-crossing detection signal and the second zero-crossing detection signal, with the purpose of adjusting the next driving time of the relay according to the advance driving time of the relay, so as to achieve driving the relay at the current zero crossing point when the relay is driven next time, thereby effectively protecting the circuit components.

[0042] In addition, the control circuit 3 of the present application can be implemented by constructing a hardware circuit, or can be directly implemented by programming an MCU (MicroController Unit), which is not particularly limited in the present application.

[0043] The present invention provides a switch drive circuit, comprising a front-stage zero-crossing detection circuit, a rear-stage zero-crossing detection circuit, and a control circuit. The front-stage zero-crossing detection circuit detects the zero-crossing point of the signal waveform input by the relay and generates a first zero-crossing detection signal; the rear-stage zero-crossing detection circuit detects the zero-crossing point of the signal waveform output by the relay and generates a second zero-crossing detection signal; the control circuit determines the delayed drive time or the advanced drive time of the relay based on the comparison result of the first zero-crossing detection signal and the second zero-crossing detection signal, and adjusts the next drive time of the relay based on the delayed drive time or the advanced drive time to drive the relay at the zero-crossing point. It can be seen that the present application can adaptively adjust the drive control time of the relay according to the actual action time of the relay to achieve the control purpose of driving the relay at the zero-crossing point, thereby avoiding the failure of the zero-crossing detection effect and playing an effective role in protecting circuit components.

[0044] Based on the above embodiment:

[0045] Please refer to Figure 2 , Figure 2 A schematic structural diagram of a front-stage zero-crossing detection circuit provided by an embodiment of the present invention.

[0046] As an optional embodiment, the front-stage zero-crossing detection circuit 1 includes a first resistor R1, a second resistor R2, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4 and a photocoupler U1; the photocoupler U1 includes a light-emitting diode and an optocoupler transistor; wherein:

[0047] The positive end of the input waveform of the relay is connected to the first end of the first resistor R1, the second end of the first resistor R1 is respectively connected to the cathode of the first diode D1 and the anode of the second diode D2, the negative end of the input waveform of the relay is respectively connected to the cathode of the third diode D3 and the anode of the fourth diode D4, the anode of the light-emitting diode is respectively connected to the anode of the first diode D1 and the anode of the third diode D3, the cathode of the light-emitting diode is respectively connected to the cathode of the second diode D2 and the cathode of the fourth diode D4, the collector of the optocoupler transistor is connected to a preset DC voltage, the emitter of the optocoupler transistor is connected to the first end of the second resistor R2 and the common end is connected to the control circuit 3, and the second end of the second resistor R2 is grounded.

[0048] Specifically, the front-stage zero-crossing detection circuit 1 of the present application includes a first resistor R1, a second resistor R2, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4 and a photoelectric coupler U1, and its working principle is:

[0049] Under normal circumstances, the relay input is a 50Hz mains waveform. When the mains waveform is a positive waveform, the light-emitting diode of the photocoupler U1 lights up, the optocoupler transistor of the photocoupler U1 is turned on, and the first end of the second resistor R2 outputs a high-level signal of about +5V; when the mains waveform is a negative waveform, the light-emitting diode of the photocoupler U1 does not light up, the optocoupler transistor of the photocoupler U1 is disconnected, and the first end of the second resistor R2 outputs a low-level signal, then the first zero-crossing detection signal is a pulse waveform.

[0050] As an optional embodiment, the structure of the subsequent zero-crossing detection circuit 2 is the same as that of the preceding zero-crossing detection circuit 1 .

[0051] Specifically, the post-stage zero-crossing detection circuit 2 includes a third resistor, a fourth resistor, a fifth diode, a sixth diode, a seventh diode, an eighth diode and a second photoelectric coupler; the second photoelectric coupler includes a second light-emitting diode and a second photocoupler transistor; wherein:

[0052] The positive end of the output waveform of the relay is connected to the first end of the third resistor, the second end of the third resistor is respectively connected to the cathode of the fifth diode and the anode of the sixth diode, the negative end of the output waveform of the relay is respectively connected to the cathode of the seventh diode and the anode of the eighth diode, the anode of the second light-emitting diode is respectively connected to the anode of the fifth diode and the anode of the seventh diode, the cathode of the second light-emitting diode is respectively connected to the cathode of the sixth diode and the cathode of the eighth diode, the collector of the second optocoupler transistor is connected to the preset DC voltage, the emitter of the second optocoupler transistor is connected to the first end of the fourth resistor and the common end is connected to the control circuit 3, and the second end of the fourth resistor is grounded.

[0053] It should be noted that the structure of the rear-stage zero-crossing detection circuit 2 of the present application is the same as that of the front-stage zero-crossing detection circuit 1, that is, the two use the same zero-crossing detection principle to perform zero-crossing detection of the signal waveform, which facilitates the comparison of the zero-crossing detection signals generated by the two.

[0054] As an optional embodiment, the control circuit 3 is specifically configured to, after the relay is actuated, determine that the relay is actuated in advance if the second zero-crossing detection signal has a detection pulse signal before the zero-point start time corresponding to the first zero-crossing detection signal, and adjust the next driving time of the relay according to T=T+(T0-T1) to drive the relay at the zero-crossing point;

[0055] Wherein, T is the driving time setting value of the relay; T0 is the zero point start time corresponding to the front-stage zero-crossing detection circuit after the relay is actuated; T1 is the zero point start time corresponding to the rear-stage zero-crossing detection circuit after the relay is actuated.

[0056] Specifically, if the relay is actuated at the zero-crossing point, then for this relay action, the zero-point start time corresponding to the first zero-crossing detection signal is consistent with the zero-point start time corresponding to the second zero-crossing detection signal, that is, the zero-crossing phases corresponding to the first zero-crossing detection signal and the second zero-crossing detection signal coincide. Figure 3 shown.

[0057] Based on this, it can be understood that if the second zero-crossing detection signal has a detection pulse signal before the zero point start time corresponding to the first zero-crossing detection signal, such as Figure 4 As shown, it means that the relay is actuated in advance, and the time for the relay to actuate in advance is: for this relay action, the zero-point start time T0 corresponding to the front-stage zero-crossing detection circuit - for this relay action, the zero-point start time T1 corresponding to the rear-stage zero-crossing detection circuit. Therefore, if you want to make the relay actuate at the zero-crossing point the next time you drive the relay, you need to delay the original setting time T of the next relay drive by (T0-T1) before driving the relay, that is, set the time for the next relay drive to T=T+(T0-T1), so as to achieve driving the relay at the current zero-crossing point.

[0058] As an optional embodiment, the control circuit 3 is specifically configured to, after the relay is actuated, determine that the relay is actuated later if the second zero-crossing detection signal has a detection pulse signal some time after the zero-point start time corresponding to the first zero-crossing detection signal, and adjust the next driving time of the relay according to T=T-(T2-T0) to drive the relay at the zero-crossing point;

[0059] Wherein, T is the driving time setting value of the relay; T0 is the zero point start time corresponding to the front-stage zero-crossing detection circuit after the relay is actuated; T2 is the zero point start time corresponding to the rear-stage zero-crossing detection circuit after the relay is actuated.

[0060] Specifically, based on the above Figure 3 It can be understood that if the second zero-crossing detection signal has a detection pulse signal some time after the zero point start time corresponding to the first zero-crossing detection signal, such as Figure 5 As shown, it means that the relay is delayed in action, and the time for the delayed action of the relay is: for this relay action, the zero-point start time T2 corresponding to the rear-stage zero-crossing detection circuit - for this relay action, the zero-point start time T0 corresponding to the front-stage zero-crossing detection circuit. Therefore, if you want to make the relay act at the zero-crossing point the next time you drive the relay, you need to advance the original setting time T of the next drive of the relay by (T2-T0) when driving the relay next time, that is, set the time for the next drive of the relay to T=T-(T2-T0), so as to achieve driving the relay at the current zero-crossing point.

[0061] As an optional embodiment, the control circuit 3 is further configured to determine that the relay is actuated at the zero-crossing point if the zero-point start times corresponding to the first zero-crossing detection signal and the second zero-crossing detection signal are consistent after the relay is actuated.

[0062] Furthermore, considering that after the relay is operated at the zero-crossing point, for this relay operation, the zero-point start time corresponding to the first zero-crossing detection signal is consistent with the zero-point start time corresponding to the second zero-crossing detection signal, so the control circuit 3 of the present application can also determine that the relay is operated at the zero-crossing point after the relay is operated, if the zero-point start time corresponding to the first zero-crossing detection signal and the second zero-crossing detection signal is consistent.

[0063] Please refer to Figure 6 , Figure 6 A flow chart of a switch driving method provided by an embodiment of the present invention.

[0064] The switch driving method is applied to any of the above switch driving circuits, including:

[0065] Step S1: The front-stage zero-crossing detection circuit detects the zero-crossing point of the signal waveform input by the relay and generates a first zero-crossing detection signal.

[0066] Step S2: The subsequent zero-crossing detection circuit detects the zero-crossing point of the signal waveform output by the relay and generates a second zero-crossing detection signal.

[0067] Step S3: The control circuit determines the delayed driving time or the advanced driving time of the relay according to the comparison result of the first zero-crossing detection signal and the second zero-crossing detection signal, and adjusts the next driving time of the relay according to the delayed driving time or the advanced driving time to drive the relay at the zero-crossing point.

[0068] For an introduction to the switch driving method provided in this application, please refer to the embodiment of the above-mentioned switch driving circuit, and this application will not go into details here.

[0069] The present application also provides a switching circuit, including a relay and any of the above-mentioned switch driving circuits.

[0070] For an introduction to the switch circuit provided in this application, please refer to the embodiment of the switch driving circuit described above, and this application will not go into details here.

[0071] It should also be noted that, in this specification, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising 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 apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0072] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use 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 intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A switch driving circuit, characterized in that: Applicable to switching circuits containing relays, including: A front-stage zero-crossing detection circuit connected to the input end of the relay is used to detect the zero-crossing point of the signal waveform input by the relay and generate a first zero-crossing detection signal; A subsequent zero-crossing detection circuit connected to the output end of the relay, for detecting a zero-crossing point of a signal waveform output by the relay and generating a second zero-crossing detection signal; a control circuit connected to the front-stage zero-crossing detection circuit and the rear-stage zero-crossing detection circuit, respectively, for determining a delayed drive time or an advanced drive time of the relay according to a comparison result of the first zero-crossing detection signal and the second zero-crossing detection signal, and adjusting a next drive time of the relay according to the delayed drive time or the advanced drive time to drive the relay at a zero-crossing point; The control circuit is specifically configured to, after the relay is actuated, determine that the relay is actuated in advance if the second zero-crossing detection signal has a detection pulse signal before the zero-point start time corresponding to the first zero-crossing detection signal, and adjust the next driving time of the relay according to T=T+(T0-T1) to drive the relay at the zero-crossing point; Wherein, T is the driving time setting value of the relay; T0 is the zero point starting time corresponding to the front-stage zero-crossing detection circuit after the relay is actuated; T1 is the zero point starting time corresponding to the rear-stage zero-crossing detection circuit after the relay is actuated; The control circuit is specifically configured to, after the relay is actuated, determine that the relay is to be actuated later if the second zero-crossing detection signal has a detection pulse signal some time after the zero-point start time corresponding to the first zero-crossing detection signal, and adjust the next driving time of the relay according to T=T-(T2-T0) so as to drive the relay at the zero-crossing point; Wherein, T is the driving time setting value of the relay; T0 is the zero point starting time corresponding to the front-stage zero-crossing detection circuit after the relay is actuated; T2 is the zero point starting time corresponding to the rear-stage zero-crossing detection circuit after the relay is actuated; The control circuit is further configured to determine that the relay is actuated at the zero-crossing point if the zero-point start times corresponding to the first zero-crossing detection signal and the second zero-crossing detection signal are consistent after the relay is actuated.

2. The switch driving circuit according to claim 1, wherein: The front-stage zero-crossing detection circuit includes a first resistor, a second resistor, a first diode, a second diode, a third diode, a fourth diode and a photoelectric coupler; the photoelectric coupler includes a light-emitting diode and an optocoupler transistor; wherein: The positive end of the input waveform of the relay is connected to the first end of the first resistor, the second end of the first resistor is respectively connected to the cathode of the first diode and the anode of the second diode, the negative end of the input waveform of the relay is respectively connected to the cathode of the third diode and the anode of the fourth diode, the anode of the light-emitting diode is respectively connected to the anode of the first diode and the anode of the third diode, the cathode of the light-emitting diode is respectively connected to the cathode of the second diode and the cathode of the fourth diode, the collector of the optocoupler is connected to a preset DC voltage, the emitter of the optocoupler is connected to the first end of the second resistor and the common end is connected to the control circuit, and the second end of the second resistor is grounded.

3. The switch driving circuit according to claim 2, wherein: The structure of the rear-stage zero-crossing detection circuit is the same as that of the front-stage zero-crossing detection circuit.

4. A switch driving method, characterized in that: The switch driving circuit according to any one of claims 1 to 3 comprises: The front-stage zero-crossing detection circuit detects the zero-crossing point of the signal waveform input by the relay and generates a first zero-crossing detection signal; The post-stage zero-crossing detection circuit detects the zero-crossing point of the signal waveform output by the relay and generates a second zero-crossing detection signal; The control circuit determines a delayed driving time or an advanced driving time of the relay according to a comparison result of the first zero-crossing detection signal and the second zero-crossing detection signal, and adjusts a next driving time of the relay according to the delayed driving time or the advanced driving time to drive the relay at a zero-crossing point; The control circuit determines the delayed driving time or the advanced driving time of the relay according to the comparison result of the first zero-crossing detection signal and the second zero-crossing detection signal, and adjusts the next driving time of the relay according to the delayed driving time or the advanced driving time to drive the relay at the zero-crossing point, including: After the relay is actuated, if the second zero-crossing detection signal has a detection pulse signal before the zero-point start time corresponding to the first zero-crossing detection signal, the control circuit determines that the relay is actuated in advance, and adjusts the next driving time of the relay according to T=T+(T0-T1) to drive the relay at the zero-crossing point; Wherein, T is the driving time setting value of the relay; T0 is the zero point starting time corresponding to the front-stage zero-crossing detection circuit after the relay is actuated; T1 is the zero point starting time corresponding to the rear-stage zero-crossing detection circuit after the relay is actuated; After the relay is actuated, if the second zero-crossing detection signal has a detection pulse signal some time after the zero-point start time corresponding to the first zero-crossing detection signal, the control circuit determines that the relay is to be actuated later, and adjusts the next driving time of the relay according to T=T-(T2-T0) so as to drive the relay at the zero-crossing point; Wherein, T is the driving time setting value of the relay; T0 is the zero point starting time corresponding to the front-stage zero-crossing detection circuit after the relay is actuated; T2 is the zero point starting time corresponding to the rear-stage zero-crossing detection circuit after the relay is actuated; The method further comprises: After the relay is actuated, the control circuit determines that the relay is actuated at the zero-crossing point if the zero-point start time corresponding to the first zero-crossing detection signal and the second zero-crossing detection signal are consistent.

5. A switching circuit, characterized in that: It includes a relay and a switch driving circuit as described in any one of claims 1 to 3.

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