Soft switching circuit, circuit board and electronic equipment

Abstract

The utility model relates to the technical field of power electronics, and discloses a soft switching circuit, a circuit board and electronic equipment. The soft switching circuit comprises a switch assembly, a control circuit, a first driving circuit and a second driving circuit, the switch assembly comprises a bidirectional thyristor and a relay, the bidirectional thyristor and the relay are connected to a first parallel connection point and a second parallel connection point in parallel, and the control circuit can detect the mains supply voltage and output a control signal according to the mains supply voltage. The first driving circuit comprises a power supply isolation circuit and a driving isolation circuit, the power supply isolation circuit can output a driving signal according to the control signal, the driving isolation circuit can drive the bidirectional thyristor to be conducted according to the driving signal, the second driving circuit can control the relay to be conducted according to the control signal, and the bidirectional thyristor is conducted before the relay is conducted. Therefore, on the basis of realizing the soft start of the relay, the cost is reduced, and the reliability and the safety of the bidirectional thyristor driving are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, in particular to a soft switch circuit, a circuit board and electronic equipment. Background Art

[0002] In the application of uninterruptible power supply and microgrid, it is often encountered that the inverter and the mains power grid switch to power the load, and the control of this switching is generally realized by a switch connected between the inverter output and the mains power grid. When the load needs to be powered by the mains power grid, the switch can be controlled to be turned on. When the load does not need to be powered by the mains power grid or the mains power grid is powered off, the switch can be controlled to be turned off. At this time, the inverter inverts the photovoltaic voltage or battery voltage to power the load. Traditional switching switches usually use relays, and voltage overshoot problems are prone to occur when the relay is turned on. Traditionally, two reverse-parallel thyristors are usually used to realize relay soft start to avoid voltage overshoot problems when the relay is turned on. Since each thyristor needs to be driven by a drive circuit, the traditional relay soft start solution uses more circuit hardware, which will increase the circuit cost. In addition, the electrical isolation of the traditional thyristor drive circuit is poor, the circuit reliability is low, and the circuit safety risk is high. Utility Model Content

[0003] One purpose of the embodiments of the utility model is to provide a soft switching circuit, a circuit board and an electronic device, which can solve the technical problems of high circuit cost, low reliability and poor safety performance of the relay soft starting solution in the prior art.

[0004] In a first aspect, an embodiment of the utility model provides a soft switching circuit, comprising:

[0005] A switch assembly, comprising a thyristor and a relay, wherein the thyristor and the relay are connected in parallel at a first parallel connection point and a second parallel connection point, wherein the first parallel connection point is used to receive mains power, and the second parallel connection point is used to be electrically connected to an inverter circuit;

[0006] A control circuit, used for detecting a mains voltage and outputting a control signal according to the mains voltage;

[0007] A first driving circuit includes a power isolation circuit and a driving isolation circuit, wherein the power isolation circuit is electrically connected to the control circuit and is used to output a driving signal according to the control signal, and the driving isolation circuit is electrically connected to the power isolation circuit and the thyristor, respectively, and is used to drive the thyristor to conduct according to the driving signal;

[0008] The second drive circuit is electrically connected to the control circuit and the relay respectively, and is used for controlling the relay to be turned on according to the control signal, wherein the thyristor is turned on before the relay.

[0009] In a second aspect, an embodiment of the utility model provides a circuit board, and the circuit board includes the soft switching circuit as described above.

[0010] In a third aspect, an embodiment of the utility model provides an electronic device, comprising the circuit board as described above.

[0011] In the soft switching circuit provided by the embodiment of the utility model, the soft switching circuit includes a switch component, a control circuit, a first drive circuit and a second drive circuit. The switch component includes a bidirectional thyristor and a relay. The bidirectional thyristor and the relay are connected in parallel at a first parallel connection point and a second parallel connection point. The first parallel connection point can receive AC power, and the second parallel connection point can be electrically connected to the inverter circuit. The control circuit can detect the AC power voltage and output a control signal according to the AC power voltage. The first drive circuit includes a power isolation circuit and a drive isolation circuit. The power isolation circuit is electrically connected to the control circuit and can output a drive signal according to the control signal. The drive isolation circuit is electrically connected to the power isolation circuit and the bidirectional thyristor respectively, and can drive the bidirectional thyristor to conduct according to the drive signal. The second drive circuit is electrically connected to the control circuit and the relay respectively, and can control the relay to conduct according to the control signal, wherein the bidirectional thyristor is turned on before the relay. Therefore, on the one hand, this embodiment connects the bidirectional thyristor in parallel with the relay, and when the control relay is turned on, the bidirectional thyristor is turned on before the relay, so as to avoid the problem of voltage overshoot at the moment of relay turning on, thereby realizing soft starting of the relay and improving circuit reliability. In addition, only one bidirectional thyristor and one driving circuit are needed to realize soft starting of the relay, so as to reduce the circuit cost on the basis of realizing soft starting of the relay. On the other hand, when driving the thyristor, this embodiment uses a power isolation circuit and a driving isolation circuit to realize double isolation, ensuring a high degree of electrical isolation between the control circuit and the bidirectional thyristor, thereby improving the reliability and safety of bidirectional thyristor driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] One or more embodiments are illustrated only as examples in the corresponding drawings, and these examples do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0013] Figure 1 This is a schematic diagram of an application scenario of a power supply system provided by an embodiment of the utility model;

[0014] Figure 2 yes Figure 1The structural schematic diagram of the inverter shown;

[0015] Figure 3 It is a structural schematic diagram of a soft switching circuit provided by an embodiment of the utility model;

[0016] Figure 4 It is a structural schematic diagram of a soft switching circuit provided by another embodiment of the utility model;

[0017] Figure 5 It is a structural schematic diagram of a soft switching circuit provided by another embodiment of the utility model;

[0018] Figure 6 The utility model provides a circuit structure diagram of a soft switching circuit. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. 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 therebetween. In addition, the terms "first", "second", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0020] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0021] Figure 1 The present invention provides an application scenario schematic diagram of a power supply system. Figure 1 As shown, the power supply system 1000 is used to supply power to a load 2000 , wherein the power supply system 1000 includes an inverter 100 , a photovoltaic assembly 200 and a commercial power grid 300 .

[0022] The inverter 100 is electrically connected to the photovoltaic assembly 200 , and can convert the variable direct current generated by the photovoltaic assembly 200 into alternating current with a commercial power frequency to supply power to the load 2000 .

[0023] The photovoltaic module 200 is a power generation device that generates direct current when exposed to sunlight. The photovoltaic module 200 is an important component of the power supply system 1000. The photovoltaic module 200 converts solar energy into electrical energy, which is either stored in a battery or used to drive the load 2000 to work.

[0024] The mains power grid 300 is a power network that transmits the mains power to the user terminal through a transmission line to supply power to the load 2000. The mains power is industrial frequency alternating current, and the mains power is characterized by three common quantities of alternating current, namely, voltage, current and frequency.

[0025] In some embodiments, see Figure 2 The inverter 100 includes a voltage conversion circuit 10 , an inverter circuit 20 and a soft switching circuit 30 .

[0026] The voltage conversion circuit 10 is electrically connected to the photovoltaic assembly 200 and can convert the variable direct current generated by the photovoltaic assembly 200, for example, output a target direct current voltage after boosting.

[0027] The inverter circuit 20 is electrically connected to the voltage conversion circuit 10 and the load 2000 respectively, and can invert the target DC voltage to output a target AC voltage, and the target AC voltage can supply power to the load 2000.

[0028] The soft switching circuit 30 is electrically connected to the inverter circuit 20 and the mains power grid 300 respectively, and can switch the inverter circuit 20 and the mains power grid 300 to power the load 2000. When the soft switching circuit 30 is in the on state, the load 2000 can be powered by the mains power grid 300. When the soft switching circuit 30 is in the off state, the load 2000 can be powered by the target AC voltage output by the inverter circuit 20.

[0029] The present invention provides a soft switching circuit. Figure 3 The soft switching circuit 30 includes a switch component 31 , a control circuit 32 , a first driving circuit 33 and a second driving circuit 34 .

[0030] like Figure 3 As shown, the switch assembly 31 includes a bidirectional thyristor 311 and a relay 312 .

[0031] The bidirectional thyristor 311 and the relay 312 are connected in parallel at a first parallel connection point 31 a and a second parallel connection point 31 b . The first parallel connection point 31 b can receive AC power, and the second parallel connection point 31 b can be electrically connected to the inverter circuit 20 .

[0032] In some embodiments, see Figure 6 The bidirectional thyristor 311 has three terminals, namely a first terminal T1, a second terminal T2 and a control terminal G. The first terminal T1 of the bidirectional thyristor 311 is connected to the first parallel connection point 31a, and the second terminal T2 of the bidirectional thyristor 311 is connected to the second parallel connection point 31b.

[0033] The triggering characteristics of the bidirectional thyristor 311 are different from those of the unidirectional thyristor. The conduction condition of the unidirectional thyristor is that a positive voltage is applied between its anode and cathode and a positive current is injected into its control electrode. For the bidirectional thyristor 311, no matter what polarity of voltage is connected between the first terminal T1 and the second terminal T2 of the bidirectional thyristor 311, as long as a trigger pulse is added to the control terminal G of the bidirectional thyristor 311, no matter what polarity of the pulse is, the bidirectional thyristor 311 can be triggered to be in the conduction state.

[0034] Therefore, when the bidirectional thyristor 311 needs to be triggered to be in the on state, no matter whether the mains voltage is in the positive half cycle or the negative half cycle, as long as a trigger pulse is added to the control terminal G of the bidirectional thyristor 311, the bidirectional thyristor 311 can be ensured to be in the on state.

[0035] It is understandable that the bidirectional thyristor 311 is an electronic switch, and its conduction time is relatively short, usually reaching the microsecond level, which is much shorter than one cycle of the mains voltage.

[0036] In some embodiments, Figure 6 As shown, the relay 312 includes a first contact 3121 , a second contact 3122 and a coil 3123 .

[0037] The first contact point 3121 is connected to the first parallel connection point 31 a , and the second contact point 3122 is connected to the second parallel connection point 31 b .

[0038] When the coil 3123 is not energized, the first contact 3121 is disconnected from the second contact 3122 , and when the coil 3123 is energized, the first contact 3121 is connected to the second contact 3122 .

[0039] It is understood that the relay 312 is a mechanical switch whose on-time is slightly longer than that of an electronic switch such as a thyristor.

[0040] The control circuit 32 can detect the mains voltage and output a control signal according to the mains voltage. In some embodiments, the control signal can be a high level signal or a low level signal.

[0041] The first driving circuit 33 includes a power isolation circuit 331 and a driving isolation circuit 332 .

[0042] The power isolation circuit 331 is electrically connected to the control circuit 32 and can output a driving signal according to a control signal.

[0043] The driving isolation circuit 332 is electrically connected to the power isolation circuit 331 and the bidirectional thyristor 311 respectively, and can drive the bidirectional thyristor 311 to conduct according to the driving signal.

[0044] Since both the power isolation circuit 331 and the drive isolation circuit 332 can perform electrical isolation, when the control circuit 32 drives the bidirectional thyristor 311 through the power isolation circuit 331 and the drive isolation circuit 332, there is double isolation between the control circuit 32 and the bidirectional thyristor 311, thereby ensuring that there is a high degree of electrical isolation between the control circuit 32 and the bidirectional thyristor 311, thereby improving the reliability and safety of driving the bidirectional thyristor 311.

[0045] The second driving circuit 34 is electrically connected to the control circuit 32 and the relay 312 respectively, and can control the relay 312 to be turned on according to the control signal.

[0046] It can be understood that although the first drive circuit 33 and the second drive circuit 34 can drive the bidirectional thyristor 311 and the relay 312 to be turned on respectively according to the control signal at the same time, as mentioned above, the conduction time of the bidirectional thyristor 311 is shorter than the conduction time of the relay 312, so the bidirectional thyristor 311 will be turned on before the relay 312. Due to the holding effect, even if the first drive circuit 33 stops applying the trigger pulse to the control terminal G of the bidirectional thyristor 311 according to the control signal at this time, the bidirectional thyristor 311 will not be turned off immediately, but will wait until the relay 312 is turned on, that is, the first contact 3121 of the relay 312 is connected to the second contact 3122, so that the current flowing through the bidirectional thyristor 311 becomes 0, and then the bidirectional thyristor 311 will be turned off.

[0047] Since when the bidirectional thyristor 311 is turned on and the relay 312 is not turned on, the voltage of the first parallel connection point 31a and the second parallel connection point 31b, that is, the voltage of the first contact 3121 and the second contact 3122 of the relay 312 is almost the same, so when the first contact 3121 and the second contact 3122 of the relay 312 are connected, there is almost no voltage overshoot, thereby avoiding the voltage overshoot problem that occurs when the relay 312 is turned on, thereby achieving soft start of the relay 312, which is beneficial to improving circuit reliability.

[0048] Moreover, since only one bidirectional thyristor and a driving circuit for driving the thyristor are needed to realize the soft start of relay 312, the circuit cost can be reduced by nearly half compared with the traditional method of using two unidirectional thyristors and two driving circuits for respectively driving the two unidirectional thyristors, thereby reducing the circuit cost while realizing the soft start of relay 312.

[0049] It can be understood that when the relay 312 is turned on, the first parallel connection point 31a and the second parallel connection point 31b are equivalent to a wire, so the conduction loss of the relay 312 is relatively small, and when the bidirectional thyristor 311 is turned on, since the bidirectional thyristor 311 is an electronic switch, it is essentially a PN junction, so the conduction loss of the bidirectional thyristor 311 is relatively large. However, as mentioned above, the bidirectional thyristor 311 will only be turned on for a very short time when the relay 2312 is needed, so the conduction loss of the bidirectional thyristor 311 can be ignored.

[0050] In some embodiments, see Figure 4 The control circuit 32 includes a mains detection circuit 321 , a zero-crossing detection circuit 322 and a controller 323 .

[0051] The mains detection circuit 321 can detect the mains voltage and output a mains detection signal.

[0052] The zero-crossing detection circuit 322 is electrically connected to the mains detection circuit 321 and can output a zero-crossing detection signal according to the mains detection signal.

[0053] The controller 323 is electrically connected to the mains detection circuit 321 , the zero-crossing detection circuit 322 , the first driving circuit 33 and the second driving circuit 34 respectively, and can output a control signal according to the mains detection signal and the zero-crossing detection signal.

[0054] In some embodiments, the controller 323 can determine whether the mains power grid 300 has power according to the mains power detection signal. If power is received, the controller 323 can determine whether the mains power crosses zero according to the zero-crossing detection signal. If it crosses zero, the controller 323 can output a control signal to the first drive circuit 33 and the second drive circuit 34 to drive the bidirectional thyristor 311 and the relay 312 to be in a conducting state. By driving the bidirectional thyristor 311 and the relay 312 to be in a conducting state at the moment when the mains power crosses zero, the switching stress of the bidirectional thyristor 311 can be reduced and the circuit reliability can be improved.

[0055] As mentioned above, when the mains power is lost, the target AC voltage output by the inverter circuit 20 generally supplies power to the load 2000, and at this time, the controller 323 drives the relay 312 to be in the disconnected state through the second drive circuit 34. When the mains power is restored, the mains power grid 300 generally supplies power to the load 2000, and at this time, the controller 323 drives the relay 312 to be in the on state through the second drive circuit 34. However, since there may be a phase and frequency difference between the target AC voltage output by the inverter circuit 20 and the mains power, if the relay 312 is driven to be in the on state at the moment of mains power restoration or when the mains power passes zero, thereby forcibly connecting the mains power grid 300 and the inverter circuit 20, it is easy to cause catastrophic consequences.

[0056] Generally speaking, it is ideal for the AC grid 300 and the inverter circuit 20 to be connected together when the phase and frequency of the AC power match the phase and frequency of the target AC voltage output by the inverter circuit 20, that is, when the AC power and the target AC voltage are phase-locked and frequency-locked.

[0057] Therefore, in some embodiments, the controller 323 can determine whether the AC power grid 300 is powered based on the AC power detection signal. If powered, the controller 323 can determine whether the AC power and the target AC voltage are successfully phase-locked and frequency-locked based on the zero-crossing detection signal. If the phase-locked and frequency-locked are successful, the controller 323 can output a control signal to the first drive circuit 33 and the second drive circuit 34 to drive the relay 312 to be in the on state.

[0058] In some embodiments, see Figure 5 The mains detection circuit 321 includes a voltage divider circuit 3211 , a differential amplifier circuit 3212 , a first filter circuit 3213 , a second current limiting protection circuit 3214 , a second filter circuit 3215 and a first clamp circuit 3216 .

[0059] The voltage divider circuit 3211 can divide the mains voltage and output a differential voltage.

[0060] In some embodiments, see Figure 6 The voltage divider circuit 3211 includes a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10 and an eleventh resistor R11.

[0061] One end of the second resistor R2 can be electrically connected to the live wire L_Grid of the AC power supply, the other end of the second resistor R2 is electrically connected to one end of the third resistor R3, the other end of the third resistor R3 is electrically connected to one end of the fourth resistor R4, the other end of the fourth resistor R4 is respectively electrically connected to one end of the fifth resistor R5 and the differential amplifier circuit 3212, the other end of the fifth resistor R5 is electrically connected to one end of the sixth resistor R6, and the other end of the sixth resistor R6 can receive an external voltage of +12V.

[0062] One end of the seventh resistor R7 can be electrically connected to the neutral line N_Grid of the AC power supply, the other end of the seventh resistor R7 is electrically connected to one end of the eighth resistor R8, the other end of the eighth resistor R8 is electrically connected to one end of the ninth resistor R9, the other end of the ninth resistor R9 is respectively electrically connected to one end of the tenth resistor R10 and the differential amplifier circuit 3212, the other end of the tenth resistor R10 is electrically connected to one end of the eleventh resistor R11, and the other end of the eleventh resistor R11 can receive an external voltage of +12V.

[0063] In this embodiment, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10 and the eleventh resistor R11 form a voltage divider network, which can reduce the peak voltage of the low-voltage zero voltage network to about 3.3V due to the voltage of the neutral line N_Grid and the live line L_Grid.

[0064] The differential amplifier circuit 3212 is electrically connected to the voltage divider circuit 3211 and can output a mains power detection signal according to the differential voltage.

[0065] In some embodiments, see Figure 6 The differential amplifier circuit 3212 includes a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a first capacitor C1 and a first operational amplifier U1.

[0066] One end of the twelfth resistor R12 is electrically connected to the voltage divider circuit 3211, the other end of the twelfth resistor R12 is electrically connected to the inverting input terminal of the first operational amplifier U1 and the first filter circuit 3213 respectively, one end of the thirteenth resistor R13 and one end of the first capacitor C1 are electrically connected to the non-inverting input terminal of the first operational amplifier U1, the other end of the thirteenth resistor R13 and the other end of the first capacitor C1 can receive an external voltage of +1.625V, and the output terminal of the first operational amplifier U1 is electrically connected to the second filter circuit 3215.

[0067] In this embodiment, the output voltage of the first operational amplifier U1, that is, the mains detection signal, is in a linear relationship in direct proportion to the mains input voltage, and the linear relationship is expressed by the following formula:

[0068]

[0069] Among them, V o1 is the mains detection signal, V in is the mains input voltage, R 13 is the resistance value of the thirteenth resistor R13, R 14 is the resistance value of the fourteenth resistor R14, R7 is the resistance value of the seventh resistor R7, R8 is the resistance value of the eighth resistor R8, R9 is the resistance value of the ninth resistor R9, R 10 is the resistance value of the tenth resistor R10.

[0070] The first filter circuit 3213 is electrically connected to the differential amplifier circuit 3212 and can perform filtering on the differential voltage.

[0071] In some embodiments, see Figure 6 , the first filtering circuit 3213 includes a fifteenth resistor R15 and a second capacitor C2.

[0072] One end of the fifteenth resistor R15 and one end of the second capacitor C2 are electrically connected to the differential amplifier circuit 3212 , and the other end of the fifteenth resistor R15 and the other end of the second capacitor C2 are electrically connected to the second filter circuit 3215 .

[0073] The fifteenth resistor R15 and the second capacitor C2 form a low-pass filter, which can filter out high-frequency interference of the differential signal input to the differential amplifier circuit 3212 .

[0074] The second current limiting protection circuit 3214 is electrically connected to the differential amplifier circuit 3212 , the first filter circuit 3213 and the control circuit 32 respectively, and can limit the current flowing into the control circuit 32 .

[0075] In some embodiments, see Figure 6 , the second current limiting protection circuit 3214 includes a sixteenth resistor R16.

[0076] One end of the sixteenth resistor R16 is electrically connected to the differential amplifier circuit 3212 , and the other end of the sixteenth resistor R16 is electrically connected to the first filter circuit 3213 and the control circuit 32 .

[0077] The second filter circuit 3215 is electrically connected to the second current limiting protection circuit 3214 , the first filter circuit 3213 , the differential amplifier circuit 3212 and the control circuit 32 respectively, and can perform filtering processing on the mains detection signal.

[0078] In some embodiments, see Figure 6 , the second filtering circuit 3215 includes a third capacitor C3.

[0079] One end of the third capacitor C3 is electrically connected to the second current limiting protection circuit 3214 , the first filter circuit 3213 , the differential amplifier circuit 3212 and the control circuit 32 , respectively, and the other end of the third capacitor C3 is grounded.

[0080] The first clamping circuit 3216 is electrically connected to the second current limiting protection circuit 3214 , the first filtering circuit 3213 , the second filtering circuit 3215 and the control circuit 32 respectively, and can clamp the mains detection signal.

[0081] In some embodiments, see Figure 6 , the first clamping circuit 3216 includes a first diode D1 and a second diode D2.

[0082] The cathode of the first diode D1 can receive an external voltage of 3.3V, the anode of the first diode D1 is electrically connected to the cathode of the second diode D2, the second current limiting protection circuit 3214, the first filter circuit 3213, the second filter circuit 3215 and the control circuit 32, and the anode of the second diode D2 is grounded.

[0083] In some embodiments, see Figure 6 The zero-crossing detection circuit 322 includes a comparison circuit 3221 , a third current limiting protection circuit 3222 , a third filtering circuit 3223 and a second clamping circuit 3224 .

[0084] The comparison circuit 3221 is electrically connected to the mains detection circuit 321 and can output a zero-crossing detection signal according to the mains detection signal.

[0085] In some embodiments, see Figure 6 The comparison circuit 3221 includes a second operational amplifier U2, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a fourth capacitor C4 and a fifth capacitor C5.

[0086] One end of the seventeenth resistor R17 is electrically connected to the AC power detection circuit 321, the other end of the seventeenth resistor R17 is electrically connected to the non-inverting input terminal of the second operational amplifier U2 and one end of the fourth capacitor C4, the other end of the fourth capacitor C4 is grounded, the inverting input terminal of the second operational amplifier U2 is electrically connected to one end of the eighteenth resistor R18, one end of the nineteenth resistor R19 and one end of the fifth capacitor C5, the other end of the eighteenth resistor R18 and the other end of the fifth capacitor C5 can receive an external voltage of +1.625V, the other end of the nineteenth resistor R19 is electrically connected to the output terminal of the second operational amplifier U2, one end of the twentieth resistor R20 and the third current limiting protection circuit 3222, and the other end of the twentieth resistor R20 can receive an external voltage of 3.3V.

[0087] In this embodiment, when the mains detection signal is greater than +1.625V, the output end of the second operational amplifier U2 outputs a high level signal, and when the mains detection signal is less than +1.625V, the output end of the second operational amplifier U2 outputs a low level signal.

[0088] The third current limiting protection circuit 3222 is electrically connected to the comparison circuit 3221 and the control circuit 32 respectively, and can limit the current flowing from the comparison circuit 3221 to the control circuit 32 .

[0089] In some embodiments, see Figure 6 , the third current limiting protection circuit 3222 includes a twenty-first resistor R21.

[0090] One end of the twenty-first resistor R21 is electrically connected to the comparison circuit 3221 , and the other end of the twenty-first resistor R21 is electrically connected to the control circuit 32 .

[0091] The third filtering circuit 3223 is electrically connected to the third current limiting protection circuit 3222 and the control circuit 32, and can perform filtering processing on the zero-crossing detection signal.

[0092] In some embodiments, see Figure 6 , the third filtering circuit 3223 includes a sixth capacitor C6.

[0093] One end of the sixth capacitor C6 is electrically connected to the third current limiting protection circuit 3222 and the control circuit 32 respectively, and the other end of the sixth capacitor C6 is grounded.

[0094] The second clamping circuit 3224 is electrically connected to the third current limiting protection circuit 3222 , the third filtering circuit 3223 and the control circuit 32 respectively, and can clamp the zero-crossing detection signal.

[0095] In some embodiments, see Figure 6 , the second clamping circuit 3224 includes a third diode D3 and a fourth diode D4.

[0096] The cathode of the third diode D3 can receive an external voltage of 3.3V, the anode of the third diode D3 is electrically connected to the cathode of the fourth diode D4, the third current limiting protection circuit 3222, the third filter circuit 3223 and the control circuit 32 respectively, and the anode of the fourth diode D4 is grounded.

[0097] In some embodiments, please refer to Figure 3 The power isolation circuit 331 includes a first switch circuit 3311 , a transformer 3312 and a second switch circuit 3313 .

[0098] The first switch circuit 3311 is electrically connected to the control circuit 32 . The first switch circuit 3311 includes a first node 33 a , and the voltage of the first node 33 a can be controlled according to a control signal.

[0099] In some embodiments, see Figure 6 The first switch circuit 3311 includes a twenty-second resistor R22, a twenty-third resistor R23, a twenty-fourth resistor R24, a twenty-fifth resistor R25, a twenty-sixth resistor R26, a twenty-seventh resistor R27, a twenty-eighth resistor R28, a twenty-ninth resistor R29, a seventh capacitor C7, a first transistor Q1, a first MOS transistor M1 and a fifth diode D5.

[0100] One end of the twenty-second resistor R22, one end of the twenty-third resistor R23 and the anode of the fifth diode D5 can receive the external voltage VCC, the other end of the twenty-second resistor R22 is electrically connected to one end of the twenty-fourth resistor R24 ​​and the control circuit 32, the other end of the twenty-fourth resistor R24 ​​is electrically connected to one end of the twenty-fifth resistor R25 and the base of the first transistor Q1, the other end of the twenty-fifth resistor R25 is grounded, the collector of the first transistor Q1 is electrically connected to the other end of the twenty-third resistor R23 and one end of the twenty-sixth resistor R26, the twenty-sixth resistor R26 is electrically connected to the base of the first transistor Q1, and the other end of the twenty-fifth resistor R25 is grounded. The other end of R26 is electrically connected to one end of the twenty-seventh resistor R27 and the gate of the first MOS transistor M1 respectively. The other end of the twenty-seventh resistor R27 and the emitter of the first transistor Q1 are grounded. The drain of the first MOS transistor M1 is electrically connected to the twenty-eighth resistor R28, the twenty-ninth resistor R29 and the transformer 3312 at the first node 33a respectively. The other end of the twenty-eighth resistor R28 is electrically connected to the transformer 3312. The other end of the twenty-ninth resistor R29 is electrically connected to one end of the seventh capacitor C7. The other end of the seventh capacitor C7 and the source of the first MOS transistor M1 are grounded.

[0101] In this embodiment, when the control signal is a high-level signal, the first transistor Q1 is in a conducting state, the first transistor Q1 pulls its collector voltage to the ground, and the first MOS transistor M1 is in a cut-off state. At this time, the voltage of the first node 33a is a high-level signal. When the control signal is a low-level signal, the first transistor Q1 is in a cut-off state, and the external voltage VCC is applied to the gate of the first MOS transistor M1 after being divided by the twenty-third resistor R23, the twenty-sixth resistor R26 and the twenty-seventh resistor R27. Therefore, the first MOS transistor M1 is in a conducting state, and the drain voltage of the first MOS transistor M1 is pulled down. At this time, the voltage of the first node 33a is a low-level signal.

[0102] The transformer 3312 is electrically connected to the first switch circuit 3311 at the first node 33a. The transformer 3312 includes a second node 33b, and the voltage of the second node 33b can be controlled according to the voltage of the first node 33a.

[0103] In some embodiments, see Figure 6 , the transformer 3312 includes a primary winding Lp and a secondary winding Ls.

[0104] The like-name end of the primary winding Lp is electrically connected to the first switch circuit 3311, the unlike-name end of the primary winding Lp is electrically connected to the first switch circuit 3311 at the first node 33a, the like-name end of the secondary winding Ls is electrically connected to the second switch circuit 3313 at the second node 33b, and the unlike-name end of the secondary winding Ls is electrically connected to the second switch circuit 3313.

[0105] In this embodiment, when the voltage of the first node 33a is a low-level signal, the primary winding Lp stores energy and is established. At this time, the voltage of the secondary winding Ls is also established. The voltage at the same-name end of the secondary winding Ls is positive and the voltage at the opposite-name end of the secondary winding Ls is negative. Therefore, at this time, the voltage of the second node 33b is a high-level signal. When the voltage of the first node 33a is a high-level signal, the primary winding Lp does not store energy. At this time, the voltage of the second node 33b is a low-level signal.

[0106] The second switch circuit 3313 is electrically connected to the transformer 3312 at the second node 33b and is electrically connected to the drive isolation circuit 332, and can output a drive signal according to the voltage of the second node 33b.

[0107] In some embodiments, please refer to Figure 4 The second switch circuit 3313 includes a first current limiting protection circuit 33131 and a switch tube 33132 .

[0108] The first current limiting protection circuit 33131 is electrically connected to the transformer 3312 at the second node 33b. The first current limiting protection circuit 33131 includes a third node 33c, and the voltage of the third node 33c can be controlled according to the voltage of the second node 33b.

[0109] In this embodiment, the first current limiting protection circuit 33131 can limit the current flowing from the transformer 3312 into the switch tube 33132 when the second node 33b is a high level signal, thereby preventing the switch tube 33132 from being damaged and protecting the switch tube 33132.

[0110] It can be understood that, in this embodiment, the voltage level type of the third node 33c is consistent with the voltage level type of the second node 33b, that is, when the voltage of the second node 33b is a high level signal, the voltage of the third node 33c is also a high level signal, and when the voltage of the second node 33b is a low level signal, the voltage of the third node 33c is also a low level signal.

[0111] In some embodiments, see Figure 6 The first current limiting protection circuit 33131 includes a sixth diode D6, a seventh diode D7, an eighth diode D8, a ninth diode D9, a thirtieth resistor R30, a thirty-first resistor R31, a thirty-second resistor R32, an eighth capacitor C8 and a ninth capacitor C9.

[0112] The anode of the sixth diode D6 is electrically connected to the transformer 3312 at the second node 33b, the cathode of the sixth diode D6 is electrically connected to the anode of the seventh diode D7, one end of the 30th resistor R30 and one end of the eighth capacitor C8, the cathode of the seventh diode D7 is electrically connected to the anode of the eighth diode D8, the cathode of the eighth diode D8 is electrically connected to the anode of the ninth diode D9, one end of the ninth capacitor C9, one end of the thirty-first resistor R31 and the switch tube 33132, the cathode of the ninth diode D9 is electrically connected to the other end of the 30th resistor R30, the other end of the eighth capacitor C8, the other end of the ninth capacitor C9 and one end of the thirty-second resistor R32, and the other end of the thirty-second resistor R32 is electrically connected to the switch tube 33132 at the third node 33c.

[0113] The switch tube 33132 is electrically connected to the first current limiting protection circuit 33131 at the third node 33c, and is electrically connected to the drive isolation circuit 332, and can output a drive signal according to the voltage of the third node 33c.

[0114] In some embodiments, see Figure 6 , the switch tube 33132 includes a second transistor Q2.

[0115] The emitter of the second transistor Q2 is electrically connected to the first current limiting protection circuit 33131 at the third node 33 c , the base of the second transistor Q2 is electrically connected to the transformer 3312 , and the collector of the second transistor Q2 is electrically connected to the driving isolation circuit 332 .

[0116] In this embodiment, when the voltage of the third node 33c is a high-level signal, the second transistor Q2 is in an on state, and the collector voltage of the second transistor Q2, that is, the driving signal is a high-level signal. When the voltage of the third node 33c is a low-level signal, the second transistor Q2 is in an off state, and the driving signal is a low-level signal.

[0117] In some embodiments, see Figure 6 , the driving isolation circuit 332 includes an optocoupler U3 and a first resistor R1.

[0118] The optocoupler U3 includes a light emitting diode VD and a photo thyristor VT. The anode and cathode of the light emitting diode VD are electrically connected to the power isolation circuit 331. One end of the photo thyristor VT is electrically connected to one end of the first resistor R1. The other end of the first resistor R1 can receive AC power. The other end of the photo thyristor VT is electrically connected to the bidirectional thyristor 311.

[0119] In this embodiment, when the driving signal is a high-level signal, current flows through the light-emitting diode VD and emits light. At this time, the photothyristor VT is in the on state after receiving the light emitted by the light-emitting diode VD. The mains power is applied to the bidirectional thyristor 311 through the first resistor R1 and the photothyristor VT, thereby triggering the bidirectional thyristor 311 to be in the on state. When the driving signal is a low-level signal, the light-emitting diode VD does not emit light. At this time, the photothyristor VT is in the off state, and the bidirectional thyristor 311 is also in the off state.

[0120] In order to further explain the working principle of the first driving circuit 33 provided in the embodiment of the utility model, Figure 6 To elaborate.

[0121] When the control signal is not a low-level signal, the first transistor Q1 is in the on state, the collector voltage of the first transistor Q1 is pulled to the ground, so at this time the first MOS tube M1 is in the off state, the voltage of the first node 33a is a high-level signal, the primary winding Lp of the transformer 3312 does not store energy, the voltage of the second node 33b is a low-level signal, the second transistor Q2 is in the off state, the drive signal is a low-level signal, at this time the light-emitting diode VD does not emit light, the photothyristor VT is in the off state, and the bidirectional thyristor 311 is also in the off state.

[0122] When the control signal is a low level signal, the first transistor Q1 is in the cut-off state, at this time the first MOS tube Q2 is in the on state, the voltage of the first node 33a is a low level signal, the primary winding Lp of the transformer 3312 stores energy, the voltage of the second node 33b is a high level signal, the second transistor Q2 is in the on state, the drive signal is a high level signal, at this time the photo thyristor VT is in the on state after receiving the light emitted by the light emitting diode VD, the AC power is applied to the bidirectional thyristor 311 through the first resistor R1 and the photo thyristor VT, thereby triggering the bidirectional thyristor 311 to be in the on state.

[0123] Please continue reading Figure 4 The second driving circuit 34 includes a third switch circuit 341 and a boost circuit 342 .

[0124] The third switch circuit 341 is electrically connected to the control circuit 32 . The third switch circuit 341 includes a fourth node 34 a , and the voltage of the fourth node 34 a can be controlled according to a control signal.

[0125] In some embodiments, see Figure 6The third switch circuit 341 includes a thirty-third resistor R33, a thirty-fourth resistor R34, a thirty-fifth resistor R35, a thirty-sixth resistor R36, a thirty-seventh resistor R37, a third transistor Q3, a second MOS transistor M2, a first Zener diode ZD1 and a second Zener diode ZD2.

[0126] One end of the thirty-third resistor R33 and one end of the thirty-fourth resistor R34 are electrically connected to the control circuit 32, the other end of the thirty-third resistor R33 and one end of the thirty-fifth resistor R35 can receive an external voltage of +12V, the other end of the thirty-fourth resistor R34 is electrically connected to one end of the thirty-sixth resistor R36 and the base of the third triode Q3, the collector of the third triode Q3 is electrically connected to the other end of the thirty-fifth resistor R35 and the cathode of the first zener diode ZD1, the anode of the first zener diode ZD1 is electrically connected to one end of the thirty-seventh resistor R37 and the gate of the second MOS tube M2, the drain of the second MOS tube M2 is electrically connected to the cathode of the second zener diode ZD2 and the relay 312 at the fourth node 34a, the anode of the second zener diode ZD2, the source of the second MOS tube M2, the other end of the thirty-seventh resistor R37 and the emitter of the third triode Q3 are grounded.

[0127] In this embodiment, when the control signal is a high-level signal, the third triode Q3 is in a conducting state, the third triode Q3 pulls its collector voltage to the ground, and the second MOS tube M2 is in a cut-off state. At this time, the voltage of the fourth node 34a is a high-level signal. When the control signal is a low-level signal, the third triode Q3 is in a cut-off state, and the external voltage +12V is applied to the gate of the second MOS tube M2 after being divided by the thirty-fifth resistor R35, the first voltage zener diode ZD1 and the thirty-seventh resistor R37. Therefore, the second MOS tube M2 is in a conducting state, and the drain voltage of the second MOS tube M2 is pulled down. At this time, the voltage of the fourth node 34a is a low-level signal.

[0128] The boost circuit 342 is electrically connected to the third switch circuit 341 and the relay at the fourth node 34a, and can receive the external voltage +12V, and boost the external voltage +12V according to the voltage of the fourth node 34a to drive the relay 312 to conduct.

[0129] Therefore, when the relay 312 needs to be driven to conduct, the boosted voltage is used to drive the relay 312 to conduct, which can increase the conduction speed of the relay 312 and reduce the conduction delay of the relay 312 as a mechanical switch.

[0130] In some embodiments, see Figure 6The boost circuit 342 includes a thirty-eighth resistor R38, a thirty-ninth resistor R39, a fortieth resistor R40, a tenth capacitor C10, an eleventh capacitor C11, a tenth diode D10, an eleventh diode D11 and a fourth transistor Q4.

[0131] One end of the thirty-eighth resistor R38 is electrically connected to the third switch circuit 341 at the fourth node 34a, and the other end of the thirty-eighth resistor R38 is electrically connected to the base of the fourth transistor Q4 and the anode of the tenth diode D10 respectively. The collector of the fourth transistor Q4 is electrically connected to one end of the thirty-ninth resistor R39, one end of the fortieth resistor R40 and one end of the tenth capacitor C10 respectively. The other end of the tenth capacitor C10 and the cathode of the eleventh diode D11 are electrically connected to the relay 312. The anode of the eleventh diode D11, the emitter of the fourth transistor Q4, the cathode of the tenth diode D10 and one end of the eleventh capacitor C11 can receive an external voltage of +12V. The other end of the eleventh capacitor C11, the other end of the thirty-ninth resistor R39 and the other end of the fortieth resistor R40 are grounded.

[0132] In this embodiment, when the voltage of the fourth node 34a is a high-level signal, the fourth transistor Q4 is in a cut-off state, and the external voltage +12V charges the tenth capacitor C10 through the eleventh diode D11, so that the voltage across the tenth capacitor C10 is 12V. When the voltage of the fourth node 34a is a low-level signal, the fourth transistor Q4 is in a conducting state, and the negative electrode voltage of the tenth capacitor C10 is 12V. At this time, since the voltage across the tenth capacitor C10 cannot change suddenly, the positive electrode voltage of the tenth capacitor C10 becomes 24V, and the 24V voltage is applied to the coil 3123 of the relay 312, so the relay 312 is in a conducting state.

[0133] In order to further explain the working principle of the second driving circuit 34 provided in the embodiment of the utility model, Figure 6 To elaborate.

[0134] When the control signal is a high level signal, the third transistor Q3 is in the on state, the third transistor Q3 pulls its collector voltage to the ground, and the second MOS transistor M2 is in the off state. At this time, the voltage of the fourth node 34a is a high level signal, the fourth transistor Q4 is in the off state, and the external voltage +12V charges the tenth capacitor C10 through the eleventh diode D11, so that the voltage across the tenth capacitor C10 is 12V. Since the second MOS transistor M2 is in the off state, no current flows through the coil 3123 of the relay 312, so the relay 312 is in the off state.

[0135] When the control signal is a low level signal, the third transistor Q3 is in a cut-off state, and the external voltage +12V is applied to the gate of the second MOS transistor M2 after being divided by the thirty-fifth resistor R35, the first voltage zener diode ZD1 and the thirty-seventh resistor R37, so the second MOS transistor M2 is in a conducting state, and the drain voltage of the second MOS transistor M2 is pulled down. At this time, the voltage of the fourth node 34a is a low level signal, the fourth transistor Q4 is in a conducting state, and the negative electrode voltage of the tenth capacitor C10 is 12V. At this time, since the voltage across the tenth capacitor C10 cannot suddenly change, the positive electrode voltage of the tenth capacitor C10 becomes 24V. Since the second MOS transistor M2 is in a conducting state, current flows through the coil 3123 of the relay 312 and the voltage across the coil 3123 is 24V, so the relay 312 is in a conducting state.

[0136] As another embodiment of the present invention, the present invention provides a circuit board, which includes the soft switch circuit as described above, wherein the circuit board can be an independent circuit board or a circuit board formed by splicing multiple circuit boards.

[0137] As another embodiment of the present invention, the embodiment of the present invention further provides an electronic device, which includes the circuit board as described above.

[0138] Finally, it should be noted that the utility model can be implemented in many different forms and is not limited to the embodiments described in this specification. These embodiments are not intended to be additional limitations on the content of the utility model. The purpose of providing these implementation methods is to make the understanding of the disclosure of the utility model more thorough and comprehensive. In addition, under the idea of ​​the utility model, the above-mentioned technical features continue to be combined with each other, and there are many other changes in different aspects of the utility model as described above, which are all considered to be within the scope of the utility model specification; further, for ordinary technicians in this field, they can be improved or transformed according to the above description, and all these improvements and transformations should belong to the scope of protection of the claims attached to the utility model.

Claims

1. A soft switching circuit, characterized in that: include: A switch assembly, comprising a bidirectional thyristor and a relay, wherein the bidirectional thyristor and the relay are connected in parallel at a first parallel connection point and a second parallel connection point, wherein the first parallel connection point is used to receive mains power, and the second parallel connection point is used to be electrically connected to an inverter circuit; A control circuit, used for detecting a mains voltage and outputting a control signal according to the mains voltage; A first driving circuit includes a power isolation circuit and a driving isolation circuit, wherein the power isolation circuit is electrically connected to the control circuit and is used to output a driving signal according to the control signal, and the driving isolation circuit is electrically connected to the power isolation circuit and the bidirectional thyristor, respectively, and is used to drive the bidirectional thyristor to conduct according to the driving signal; The second driving circuit is electrically connected to the control circuit and the relay respectively, and is used for driving the relay to conduct according to the control signal, wherein the bidirectional thyristor is conducted before the relay.

2. The soft switching circuit according to claim 1, characterized in that: The power isolation circuit comprises: a first switch circuit, electrically connected to the control circuit, the first switch circuit comprising a first node, and configured to control a voltage of the first node according to the control signal; a transformer electrically connected to the first switch circuit at the first node, the transformer comprising a second node for controlling a voltage of the second node according to a voltage of the first node; The second switch circuit is electrically connected to the transformer at the second node and to the drive isolation circuit, and is used for outputting a drive signal according to the voltage of the second node.

3. The soft switching circuit according to claim 2, characterized in that: The second switch circuit comprises: a first current limiting protection circuit, electrically connected to the transformer at the second node, the first current limiting protection circuit comprising a third node, configured to control a voltage of the third node according to a voltage of the second node; A switch tube is electrically connected to the first current limiting protection circuit at the third node and is electrically connected to the drive isolation circuit, and is used to output a drive signal according to the voltage of the third node.

4. The soft switching circuit according to claim 1, characterized in that: The driving isolation circuit includes an optical coupler and a first resistor; The optocoupler includes a light emitting diode and a photothyristor, the anode and cathode of the light emitting diode are electrically connected to the power isolation circuit, one end of the photothyristor is electrically connected to one end of the first resistor, the other end of the first resistor is used to receive AC power, and the other end of the photothyristor is electrically connected to the bidirectional thyristor.

5. The soft switching circuit according to claim 1, characterized in that: The second driving circuit comprises: a third switch circuit, electrically connected to the control circuit, the third switch circuit comprising a fourth node, and configured to control a voltage of the fourth node according to the control signal; The boost circuit is electrically connected to the third switch circuit and the relay at the fourth node, and is used to receive an external voltage and drive the relay to conduct after boosting the external voltage according to the voltage of the fourth node.

6. The soft switching circuit according to claim 1, characterized in that: The control circuit comprises: A mains detection circuit, used to detect the mains voltage and output a mains detection signal; A zero-crossing detection circuit, electrically connected to the mains detection circuit, and configured to output a zero-crossing detection signal according to the mains detection signal; The controller is electrically connected to the mains detection circuit, the zero-crossing detection circuit, the first drive circuit and the second drive circuit respectively, and is used to output a control signal according to the mains detection signal and the zero-crossing detection signal.

7. The soft switching circuit according to claim 6, characterized in that: The mains power detection circuit comprises: A voltage divider circuit, used for dividing the mains voltage and outputting a differential voltage; A differential amplifier circuit, electrically connected to the voltage divider circuit, and configured to output a mains power detection signal according to the differential voltage; a first filtering circuit, electrically connected to the differential amplifier circuit, and configured to filter the differential voltage; a second current limiting protection circuit, electrically connected to the differential amplifier circuit, the first filter circuit and the control circuit respectively, and used for limiting the current flowing from the differential amplifier circuit into the control circuit; A second filtering circuit is electrically connected to the second current limiting protection circuit, the first filtering circuit and the control circuit respectively, and is used for filtering the mains detection signal; The first clamping circuit is electrically connected to the second current limiting protection circuit, the first filtering circuit, the second filtering circuit and the control circuit respectively, and is used for clamping the mains detection signal.

8. The soft switching circuit according to claim 6, characterized in that: The zero-crossing detection circuit comprises: A comparison circuit, electrically connected to the mains detection circuit, and configured to output a zero-crossing detection signal according to the mains detection signal; A third current limiting protection circuit is electrically connected to the comparison circuit and the control circuit respectively, and is used to limit the current flowing from the comparison circuit to the control circuit; A third filtering circuit is electrically connected to the third current limiting protection circuit and the control circuit respectively, and is used for filtering the zero-crossing detection signal; The second clamping circuit is electrically connected to the third current limiting protection circuit, the third filtering circuit and the control circuit respectively, and is used for clamping the zero-crossing detection signal.

9. A circuit board, characterized in that: Comprising the soft switching circuit as claimed in any one of claims 1 to 8.

10. An electronic device, characterized in that: Comprising the circuit board as claimed in claim 9.

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