Circuit and device for isolating driving and detecting bidirectional switches

Abstract

The present invention discloses a circuit and device for isolating, driving, and detecting a bidirectional switch, the circuit comprising: a first circuit, the first circuit comprising a switch driving circuit, a driving signal detection circuit, and a bidirectional switch coupled in sequence; a second circuit, the second circuit comprising a load access signal detection circuit, a high-order harmonic generation circuit, and a load coupled in sequence; the load being coupled to the bidirectional switch; a decoupling circuit, the first end of the decoupling circuit being coupled to the switch driving circuit and the driving signal detection circuit respectively; the second end of the decoupling circuit being coupled to the load access signal detection circuit and the high-order harmonic generation circuit respectively. The technical solution of the present invention realizes the driving and detection functions of the bidirectional switch using a single isolation device, so that the isolation device has the bidirectional transmission capability of the signal, saves the number of isolation devices, and saves cost and space.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor switch control, and in particular relates to a circuit and device for isolating, driving and detecting a bidirectional switch. Background Art

[0002] Semiconductor bidirectional switches are primarily used to control the on / off switching of alternating currents. They typically consist of two field-effect transistors (FETs) or transistors connected in series in opposite directions. When implementing bidirectional switches in actual products, considerations such as electromagnetic compatibility (EMC), surge protection, and anti-static requirements must be taken into account. Therefore, isolated drivers are often required.

[0003] However, the signal flow of the isolation components in existing isolated bidirectional switches is unidirectional. This means that the switch can only be controlled through the isolation component, and the switch's operating status cannot be retrieved in the reverse direction. To obtain the switch's operating status in the reverse direction, an additional isolation circuit is required, which results in redundant and costly circuit design. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, one object of the present invention is to provide a circuit and device for isolating driving and detecting a bidirectional switch.

[0005] In order to solve the above technical problems, the embodiments of the present invention provide the following technical solutions:

[0006] A circuit for isolating driving and detecting a bidirectional switch, comprising:

[0007] A first circuit, comprising a switch driving circuit, a driving signal detection circuit, and a bidirectional switch coupled in sequence;

[0008] a second circuit, the second circuit comprising a load access signal detection circuit, a high-order harmonic generation circuit, and a load coupled in sequence; the load is coupled to the bidirectional switch;

[0009] A decoupling circuit, wherein a first end of the decoupling circuit is coupled to the switch driving circuit and the driving signal detection circuit respectively; a second end of the decoupling circuit is coupled to the load access signal detection circuit and the high-order harmonic generating circuit respectively.

[0010] Optionally, the load is connected to a signal detection circuit, including:

[0011] The first triode and signal transformer;

[0012] The collector of the first transistor is coupled to the GPIO, the emitter of the first transistor is grounded, and the base of the first transistor is coupled to the same-name terminal of the primary coil of the signal transformer.

[0013] Optionally, the load is connected to the high-order harmonic generating circuit;

[0014] The high-order harmonic generating circuit sends the high-order harmonics to the signal transformer and turns on the first transistor.

[0015] Optionally, the switch driving circuit includes:

[0016] Second triode;

[0017] The base of the second transistor is coupled to the GPIO, the emitter of the second transistor is coupled to VCC, and the collector of the second transistor is coupled to the same-name terminal of the primary coil of the signal transformer.

[0018] Optionally, the GPIO sends the high-frequency carrier to the signal transformer through the second transistor.

[0019] Optionally, the decoupling circuit includes:

[0020] The third MOS tube;

[0021] The gate of the third MOS transistor is coupled to the opposite-name end of the secondary coil of the signal transformer, the source of the third MOS transistor is coupled to the same-name end of the secondary coil of the signal transformer; and the drain of the third MOS transistor is coupled to the drive signal detection circuit.

[0022] Optionally, the decoupling circuit further includes:

[0023] A fourth capacitor, wherein a first end of the fourth capacitor is coupled to the opposite-name end of the secondary coil of the signal transformer, and a second end of the fourth capacitor is coupled to a power supply.

[0024] Optionally, the high-order harmonic generating circuit includes:

[0025] a seventh triode, an eighth triode, a ninth triode, a tenth triode, and an eleventh triode;

[0026] The emitter of the seventh transistor is coupled to the emitter of the eighth transistor and the same-name terminal of the secondary coil of the signal transformer respectively, the base of the seventh transistor is coupled to the power supply, and the collector of the seventh transistor is coupled to the collector of the tenth transistor;

[0027] The emitter of the eighth transistor is coupled to the same-name terminal of the secondary coil of the signal transformer, the base of the eighth transistor is coupled to the bidirectional switch and the load respectively, and the collector of the eighth transistor is coupled to the collector of the eleventh transistor;

[0028] The collector of the ninth transistor is coupled to the same-name terminal of the secondary coil of the signal transformer; the emitter of the ninth transistor is coupled to the emitter of the tenth transistor and the emitter of the eleventh transistor respectively;

[0029] The emitter of the tenth transistor is coupled to the emitter of the eleventh transistor, and the base of the tenth transistor is coupled to the base of the eleventh transistor.

[0030] Optionally, the driving signal detection circuit includes:

[0031] A second capacitor, wherein a first end of the second capacitor is coupled to the drain of the third MOS tube; and a second end of the second capacitor is coupled to the bidirectional switch and the load respectively.

[0032] An embodiment of the present invention further provides a device for isolating, driving, and detecting a bidirectional switch, including the circuit described above.

[0033] The embodiments of the present invention have the following technical effects:

[0034] The above technical solution of the present invention: 1) a single isolation device is used to realize the driving and detecting functions of the bidirectional switch, so that the isolation device has the bidirectional transmission capability of the signal, saves the number of isolation devices, and saves cost and space.

[0035] 2) The same signal transformer T1 transmits both the driving and detection signals, and the two signals do not affect each other. Therefore, the circuit of the embodiment of the present invention realizes the multiplexing of the driving and detection signals.

[0036] 3) The decoupling circuit ensures that the current of the driving signal can only charge the second capacitor from the same-name terminal of the signal transformer, and when the current of the load connected detection signal flows into the signal transformer from the same-name terminal, it will not charge the second capacitor, thereby preventing the switch from being driven incorrectly, thereby achieving signal decoupling.

[0037] 4) The high-order harmonic generation circuit has a high amplification factor, and the output edge bandwidth is high enough during state switching to generate high-order harmonics. These high-order harmonics drive the signal transformer through the fourth MOS transistor. The decoupling circuit ensures that the high-order harmonics do not affect the driving function of the bidirectional switch. If the load is not connected, the phases of node Y and terminal C are the same, and no high-order harmonics are generated.

[0038] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a structural block diagram of a circuit for isolating, driving, and detecting a bidirectional switch provided by an embodiment of the present invention;

[0040] Figure 2 The figure is a schematic diagram of the working principle of the circuit for isolating driving and detecting a bidirectional switch provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0042] In order to facilitate those skilled in the art to understand the embodiments, some terms are explained:

[0043] (1) MOS transistor: MOSFET transistor; generally a metal-oxide-semiconductor field-effect transistor, or metal-insulator-semiconductor. G: gate; S: source; D: drain.

[0044] (2) GPIO: General-purpose input / output, short for general-purpose input / output.

[0045] (3) HVAC: Heating, Ventilation and Air Conditioning.

[0046] (4) MCU: Microcontroller Unit, microcontroller unit.

[0047] (5) PWM: Pulse width modulation, various pulse width modulations.

[0048] like Figure 1 As shown, an embodiment of the present invention provides a circuit for isolating driving and detecting a bidirectional switch, comprising:

[0049] A first circuit, comprising a switch driving circuit, a driving signal detection circuit, and a bidirectional switch coupled in sequence;

[0050] a second circuit, the second circuit comprising a load access signal detection circuit, a high-order harmonic generation circuit, and a load coupled in sequence; the load is coupled to the bidirectional switch;

[0051] A decoupling circuit, wherein a first end of the decoupling circuit is coupled to the switch driving circuit and the driving signal detection circuit respectively; a second end of the decoupling circuit is coupled to the load access signal detection circuit and the high-order harmonic generating circuit respectively.

[0052] Specifically, the load is usually a passive load, commonly a lamp, a relay, etc.

[0053] R and C are two terminals of the AC power supply. The AC power supply parameters can be 100-240Vac 50 / 60Hz for the lighting system or 18-30Vac 50 / 60Hz for the HVAC system.

[0054] In the embodiment of the present invention, a single isolation device is used to realize the driving and detecting functions of a bidirectional switch, so that the isolation device has the bidirectional transmission capability of signals, saves the number of isolation devices, and saves cost and space.

[0055] like Figure 2 As shown, in an optional embodiment of the present invention, the load is connected to the signal detection circuit, including:

[0056] The first transistor Q1 and the signal transformer T1;

[0057] The collector of the first transistor Q1 is coupled to the GPIO, the emitter of the first transistor Q1 is grounded, and the base of the first transistor Q1 is coupled to the same-name terminal of the primary coil of the signal transformer T1.

[0058] It also includes: a first diode D1, a first capacitor C1, a first resistor R1, a second resistor R2 and a third resistor R3;

[0059] The base of the first transistor Q1 is coupled to the first end of the second resistor R2, and the second end of the second resistor R2 is coupled to the first end of the third resistor R3, the first end of the first capacitor C1, and the output end of the first diode D1 respectively;

[0060] A second end of the third resistor R3 is grounded and coupled to the second end of the first capacitor C1;

[0061] An input terminal of the first diode D1 is coupled to the same-name terminal of the primary coil of the signal transformer T1 and the switch driving circuit respectively.

[0062] In an embodiment of the present invention, a load access signal detection circuit is used to detect higher harmonics. When higher harmonics pass through the signal transformer T1, the first transistor Q1 is turned on, and the MCU receives a low level, corresponding to a state in which a load is connected; the MCU receives a high level, corresponding to a state in which no load is connected; the bandwidth of the drive signal from the MCU needs to be staggered with the bandwidth of the higher harmonics to avoid mutual interference; or the second transistor Q2 is disconnected when the load state is detected, which can also achieve decoupling of the drive signal and the load access detection signal.

[0063] like Figure 2 As shown, in an optional embodiment of the present invention, the load is connected to the high-order harmonic generating circuit;

[0064] The high-order harmonic generating circuit sends the high-order harmonics to the signal transformer T1 and turns on the first transistor Q1.

[0065] like Figure 2 As shown, in an optional embodiment of the present invention, the switch driving circuit includes:

[0066] The second transistor Q2;

[0067] The base of the second transistor Q2 is coupled to the GPIO, the emitter of the second transistor Q2 is coupled to VCC, and the collector of the second transistor Q2 is coupled to the same-name terminal of the primary coil of the signal transformer T1.

[0068] Also includes: a zeroth resistor R0, a fourth resistor R4 and a signal transformer T1;

[0069] Wherein, a first end of the zeroth resistor R0 is coupled to the GPIO, a second end of the zeroth resistor R0 is coupled to the base of the second transistor Q2, and an emitter of the second transistor Q2 is coupled to the power supply;

[0070] The collector of the second transistor Q2 is coupled to the first end of the fourth resistor R4 . The second end of the fourth resistor R4 is coupled to the input end of the first diode D1 and the same-name terminal of the primary coil of the signal transformer T1 .

[0071] In an embodiment of the present invention, the driving signal comes from the GPIO of the MCU. When the GPIO output is at a high level, the second transistor Q2 is not conductive and the driving signal cannot pass through the signal transformer T1. When the GPIO outputs a high-frequency carrier signal, the second transistor Q2 is driven to operate in a high-frequency switching state, and the operating frequency of the second transistor Q2 is consistent with the high-frequency carrier signal output by the GPIO, and the high-frequency carrier signal can pass through the signal transformer T1.

[0072] like Figure 2As shown, in an optional embodiment of the present invention, the GPIO sends the high-frequency carrier to the signal transformer T1 through the second transistor Q2.

[0073] In an optional embodiment of the present invention, the decoupling circuit includes:

[0074] The third MOS tube Q3;

[0075] The gate of the third MOS transistor Q3 is coupled to the opposite-name terminal of the secondary winding of the signal transformer T1, the source of the third MOS transistor Q3 is coupled to the same-name terminal of the secondary winding of the signal transformer T1; and the drain of the third MOS transistor Q3 is coupled to the drive signal detection circuit.

[0076] like Figure 2 As shown, in an optional embodiment of the present invention, the decoupling circuit further includes:

[0077] A fourth capacitor C4 , wherein a first end of the fourth capacitor C4 is coupled to the opposite-polarity terminal of the secondary winding of the signal transformer T1 , and a second end of the fourth capacitor C4 is coupled to a power supply.

[0078] Specifically, the second end of the fourth capacitor C4 is coupled to the terminal C of the AC power supply.

[0079] In an embodiment of the present invention, the decoupling circuit ensures that the current of the drive signal can only charge the second capacitor C2 from the same-name terminal of the secondary coil of the signal transformer T1. Furthermore, when the current of the load connection detection signal flows from the same-name terminal of the secondary coil of the signal transformer T1 into the signal transformer T1, the second capacitor C2 will not be charged, thereby preventing the switch from being driven incorrectly, thereby achieving signal decoupling.

[0080] like Figure 2 As shown, in an optional embodiment of the present invention, the high-order harmonic generating circuit includes:

[0081] a seventh transistor Q7, an eighth transistor Q8, a ninth transistor Q9, a tenth transistor, and an eleventh transistor Q11;

[0082] The emitter of the seventh transistor Q7 is coupled to the emitter of the eighth transistor Q8 and the same-name terminal of the secondary coil of the signal transformer T1 respectively, the base of the seventh transistor Q7 is coupled to the power supply, and the collector of the seventh transistor Q7 is coupled to the collector of the tenth transistor;

[0083] The emitter of the eighth transistor Q8 is coupled to the same-name terminal of the secondary coil of the signal transformer T1, the base of the eighth transistor Q8 is coupled to the bidirectional switch and the load respectively, and the collector of the eighth transistor Q8 is coupled to the collector of the eleventh transistor Q11;

[0084] The collector of the ninth transistor Q9 is coupled to the same-name terminal of the secondary coil of the signal transformer T1; the emitter of the ninth transistor Q9 is coupled to the emitter of the tenth transistor and the emitter of the eleventh transistor Q11 respectively;

[0085] The emitter of the tenth transistor is coupled to the emitter of the eleventh transistor Q11 , and the base of the tenth transistor is coupled to the base of the eleventh transistor Q11 .

[0086] Also included: a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, and a thirteenth resistor R13;

[0087] A first end of the tenth resistor R10 is coupled to the terminal C of the AC power supply, and a second end of the tenth resistor R10 is coupled to the base of the seventh transistor Q7. A first end of the eleventh resistor R11 is coupled to the source of the fourth MOS transistor Q4. A second end of the eleventh resistor R11 is coupled to the gate of the fourth MOS transistor Q4 and the collector of the ninth transistor Q9.

[0088] A first end of the twelfth resistor R12 is coupled to the source of the fourth MOS transistor Q4 , and a second end of the twelfth resistor R12 is coupled to the emitter of the seventh transistor Q7 and the emitter of the eighth transistor Q8 ;

[0089] A first end of the thirteenth resistor R13 is coupled to the base of the eighth transistor Q8 , and a second end of the thirteenth resistor R13 is coupled to the load and the bidirectional switch respectively.

[0090] Since the current passing through the load and the bidirectional switch is the power frequency current, which cannot pass through the signal transformer T1, it is necessary to convert the load access detection signal into a high-frequency signal.

[0091] In the embodiment of the present invention, since the power frequency current (frequency is usually equal to 50Hz or 60Hz) passes through the load and the bidirectional switch, the power frequency signal cannot pass through the signal transformer T1. Therefore, it is necessary to convert the load access detection signal into a high-frequency signal, and the high-order harmonic generating circuit realizes this function.

[0092] The high-order harmonic generation circuit has a high amplification factor, and the output edge bandwidth is high enough during state switching to generate high-order harmonics. These high-order harmonics drive the signal transformer T1 through the fourth MOS transistor Q4. The decoupling circuit ensures that the high-order harmonics do not affect the driving function of the bidirectional switch. If the load is not connected, the phases of node Y and terminal C are the same, and no high-order harmonics are generated.

[0093] like Figure 2 As shown, in an optional embodiment of the present invention, the driving signal detection circuit includes:

[0094] A second capacitor C2, wherein a first end of the second capacitor C2 is coupled to the drain of the third MOS transistor Q3; and a second end of the second capacitor C2 is coupled to the bidirectional switch and the load respectively.

[0095] It also includes: a fifth resistor R5, a seventh resistor R7, a third capacitor C3, a fourth capacitor C4, a second diode D2, a third MOS transistor Q3 and a signal transformer T1;

[0096] The first end of the third capacitor C3 is coupled to the same-name terminal of the secondary coil of the signal transformer T1, the second end of the third capacitor C3 is coupled to the input end of the second diode D2, and the input end of the second diode D2 is also coupled to the drain of the third MOS transistor Q3;

[0097] An output end of the second diode D2 is coupled to a first end of the fifth resistor R5, a first end of the second capacitor C2, and a first end of the ninth resistor R9, respectively;

[0098] A second end of the fifth resistor R5 is coupled to a second end of the second capacitor C2 .

[0099] In an embodiment of the present invention, based on the characteristics of signal transformer T1, the primary high-frequency current can be transmitted to the secondary coil via magnetic coupling, forming a secondary high-frequency current in the secondary coil of signal transformer T1. Since signal transformer T1 cannot transmit low-frequency components, the low-frequency components of the high-frequency current are filtered out, and current pulses with the same frequency as the primary coil flow through the secondary coil of signal transformer T1. These current pulses have alternating polarity. That is, when the current flowing into the same-name terminal of the primary coil is on a rising edge, the current pulse flowing into the same-name terminal of the secondary coil is positive; when the current flowing into the same-name terminal of the primary coil is on a falling edge, the current pulse flowing into the same-name terminal of the secondary coil is negative.

[0100] The circuit of the present invention further includes: a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a fifth MOS transistor Q5, a sixth MOS transistor Q6, a third diode D3, a fourth diode D4, a fifth diode D5, a fifth capacitor C5, a sixth diode D6, a sixth capacitor C6, a seventh diode D7, a seventh resistor R7, a sixth resistor R6, and an eighth resistor R8;

[0101] The bidirectional switch includes a fifth MOS transistor Q5, a sixth MOS transistor Q6, a third diode D3 and a fourth diode D4;

[0102] Specifically, the second end of the load is coupled to the terminal R of the AC power supply, the input end of the fifth diode D5, the input end of the sixth diode D6, and the output end of the seventh diode D7 respectively;

[0103] The first end of the load is coupled to the second end of the fourteenth resistor R14 and the drain of the fifth MOS transistor Q5 respectively;

[0104] The drain of the fifth MOS transistor Q5 is coupled to the output end of the third diode D3; the gate of the fifth MOS transistor Q5 is coupled to the first end of the fifteenth resistor R15 and the gate of the sixth MOS transistor Q6 respectively;

[0105] The source of the fifth MOS transistor Q5 is coupled to the second end of the fifteenth resistor R15 and the source of the sixth MOS transistor Q6 respectively;

[0106] The drain of the sixth MOS transistor Q6 is coupled to the output end of the fourth diode D4 and the terminal C respectively;

[0107] An output terminal of the fifth diode D5 is coupled to a first terminal of the fifth capacitor C5, a second terminal of the fifth resistor R5, and a second terminal of the second capacitor C2 respectively;

[0108] A second terminal of the fifth capacitor C5 is coupled to a second terminal of the fifteenth resistor R15;

[0109] An output terminal of the sixth diode D6 is coupled to a first terminal of the sixth capacitor C6, a first terminal of the twelfth resistor R12, and a first terminal of the eleventh resistor R11 respectively;

[0110] The second end of the sixth capacitor C6 is coupled to the second end of the sixteenth resistor R16 and the terminal C respectively;

[0111] An input terminal of the seventh diode D7 is coupled to the emitter of the tenth transistor, the emitter of the eleventh transistor Q11 and the first terminal of the seventh capacitor C7 respectively;

[0112] The second end of the seventh capacitor C7 is coupled to the terminal C, the second end of the sixteenth resistor R16 , the drain of the sixth MOS transistor Q6 , and the output end of the fourth diode D4 , respectively.

[0113] A first end of the sixth resistor R6 is coupled to the gate of the third MOS transistor Q3 and the same-name terminal of the secondary coil of the signal transformer T1 respectively;

[0114] The second end of the sixth resistor R6 is coupled to the drain of the fourth MOS transistor Q4 and the first end of the eighth resistor R8 respectively;

[0115] A first end of the eighth resistor R8 is coupled to the drain of the fourth MOS transistor Q4;

[0116] A second end of the eighth resistor R8 is coupled to the terminal C of the AC power source.

[0117] like Figure 2 As shown, the above embodiments of the present invention are implemented based on the following working principles:

[0118] (1) The high-frequency carrier drives the bidirectional switch through the signal transformer:

[0119] 1. When the bidirectional switch needs to be disconnected, the MCU outputs a high level and no high-frequency signal exists. At this time, the second capacitor cannot be charged. Since the fifth resistor R5 will continue to discharge, the voltage of the second capacitor C2 cannot be maintained. Therefore, the bidirectional switch is disconnected.

[0120] 2. When the bidirectional switch needs to be turned on, the MCU outputs a high-frequency square wave voltage. This high-frequency square wave voltage is applied to the first pin of the zeroth resistor R0, driving the second transistor Q2 to operate in a high-frequency switching state. The operating frequency matches the high-frequency square wave output by the MCU. The high-frequency current flows from the VCC power supply in sequence into the second transistor, the fourth resistor R4, the primary coil of the signal transformer T1, and the reference ground.

[0121] The third MOS transistor Q3 is a pulse selection switch. When the current pulse flowing out of the same-name terminal of the secondary coil of the signal transformer T1 is positive and the generated pulse voltage amplitude is greater than the turn-on voltage of the third MOS transistor Q3, the third MOS transistor Q3 is turned on. At this time, the pulse current flows in sequence to the third MOS transistor Q3, the second diode D2, the second capacitor C2, the fifth capacitor C5, the fourth diode D4, the fourth capacitor C4, and the secondary coil of the signal transformer T1. This current path charges the second capacitor C2. When the average charging current is equal to the average current consumed by the fifth resistor R5, the voltage across the second capacitor C2 remains stable.

[0122] Among them, by selecting appropriate circuit parameters, especially the values ​​of the second capacitor C2 and the fifth resistor R5, and the frequency of the high-frequency square wave output by the MCU, the voltage across the second capacitor C2 can be higher than the turn-on voltage of the bidirectional switch. At this time, the bidirectional switch is turned on.

[0123] (2) Using a high-frequency carrier to detect the load connection status through the signal transformer T1:

[0124] 1. The seventh transistor Q7 and the eighth transistor Q8, the thirteenth transistor Q10 and the eleventh transistor Q11 are transistor pairs, and have similar electrical parameters. The first current flows from the sixth capacitor C6 to the twelfth resistor R12, the seventh transistor Q7, the tenth transistor Q10, and the seventh capacitor C7 in sequence;

[0125] 2. The second current flows from the sixth capacitor C6 to the twelfth resistor R12, the eighth transistor Q8, the eleventh transistor Q11, and the seventh capacitor C7 in sequence. When no load is connected, there is no voltage drop between nodes Y and C, the first current equals the second current, the tenth transistor Q10 and the eleventh transistor Q11 are both critically conductive, the current flowing through the collector of the ninth transistor Q9 is very small, and the ninth transistor Q9 is cut off. As a result, the source and gate voltages of the fourth MOS transistor Q4 are equal, the fourth MOS transistor Q4 is also non-conductive, and the high-order harmonic generating circuit cannot drive the signal transformer T1. At this time, the first capacitor C1 cannot generate a voltage drop, the first transistor Q1 is non-conductive, and the collector of the first transistor Q1 is high, indicating that no load is connected. When a load is connected, there is a voltage drop between nodes Y and C. This voltage drop is the power frequency voltage, which is applied to the first terminal pin of the tenth resistor R10 and the second terminal pin of the thirteenth resistor R13, respectively. When the base voltage of the seventh transistor Q7 is greater than the base voltage of the eighth transistor Q8, since the eleventh transistor Q11 operates in the critical region between the saturation region and the amplification region, and the current flowing through the collector of the seventh transistor Q7 needs to be smaller than the current flowing through the collector of the eighth transistor Q8, the current flowing through the collector of the tenth transistor Q10 must also be smaller than that of the eleventh transistor Q11. At this time, the tenth transistor Q10 enters the saturation region, resulting in a decrease in the collector current. The decrease in the collector current of the tenth transistor Q10 further aggravates the decrease in the collector current of the seventh transistor Q7. Therefore, the collector currents of the seventh transistor Q7 and the tenth transistor Q10 form positive feedback with each other, and ultimately both the seventh transistor Q7 and the tenth transistor Q10 are turned off. At this time, the ninth transistor Q10 enters the saturation region, resulting in a decrease in the collector current. Transistor Q9 is off, and neither is the fourth MOS transistor Q4. Similarly, when the base voltage of the seventh transistor Q7 is lower than the base voltage of the eighth transistor Q8, the collector currents of the seventh transistor Q7 and the tenth transistor Q10 generate positive feedback, ultimately increasing the collector currents of both transistors Q7 and Q10, shifting their operating states into the amplification region. At this point, the collector-emitter voltage drop of the tenth transistor Q10 exceeds the base-emitter turn-on threshold of the ninth transistor Q9, causing the ninth transistor Q9 to conduct, and the fourth MOS transistor Q4 to also conduct. Ultimately, the fourth MOS transistor Q4 switches between on and off states at the power frequency. The above analysis shows that the state switching is a positive feedback process, with steep waveform edges, indicating the generation of high-order harmonics.

[0126] The high-harmonic generation circuit generates a steep square wave voltage. The generated current flows sequentially through the fourth MOS transistor Q4, the sixth resistor R6, the signal transformer T1, the fourth capacitor C4, and the sixth capacitor C6, thereby driving the secondary coil of the signal transformer T1. This process generates a pulse current in the primary of the signal transformer T1. The pulse current flows into the first diode D1 and the first capacitor C1, causing a voltage drop across the first capacitor C1. This voltage drop, after passing through the second resistor R2, drives the first transistor Q1 to conduct. The collector of the first transistor Q1 is at a low level, indicating that a load is connected.

[0127] (3) Decoupling principle:

[0128] 1. Decoupling of activation and detection:

[0129] When the bidirectional switch needs to be turned on, if no load is connected, the high-order harmonic generation circuit has no output, so load detection behavior does not affect the bidirectional switch drive. If a load is connected, the current pulses output by the high-order harmonic generation circuit do not affect the bidirectional switch drive. This is because the frequency of the primary high-frequency square wave is much higher than the power frequency, and the number of high-frequency current pulses generated is far greater than the number of pulses generated by load detection. Even if a small portion of the pulses are offset by the load detection current pulses, the majority of the pulses remain unaffected. Therefore, the activation of the bidirectional switch is unrelated to the load detection behavior.

[0130] 2. Decoupling of shutdown and detection:

[0131] When the bidirectional switch needs to be disconnected, the MCU outputs a high level. If the load is not connected, there is no high-frequency signal in the entire circuit, and all signals cannot pass through the transformer. At this time, the load detection module has no signal output, the transformer has no signal output, and the second capacitor C2 cannot be charged, so the bidirectional switch cannot be turned on. If the load is connected, without the third MOS tube Q3 of the pulse selection switch, the industrial frequency power supply will charge the second capacitor C2 through the current loop composed of the fourth capacitor C4, the secondary coil of the signal transformer T1, the second diode D2, the second capacitor C2, the third diode D3 and the load, causing the bidirectional switch to malfunction and decoupling to fail.

[0132] To achieve successful decoupling, the circuit of the present invention incorporates a third MOS transistor Q3, a pulse selection switch. Since the impedance of the signal transformer T1 is very low at the power frequency, the voltage drop across the secondary coil is very low, insufficient to turn on the third MOS transistor Q3. At this point, the power frequency charging circuit of the second capacitor C2 is cut off, preventing malfunction while ensuring that the driver-end pulse can normally charge the second capacitor C2. Furthermore, excessively large pulses generated by the load detection circuit can also cause the charging voltage of the second capacitor C2 to exceed the bidirectional switch's conduction voltage, leading to malfunction. In this case, a fourth capacitor C4 is required to adjust the intensity of the load detection current pulse flowing through the secondary coil of the signal transformer T1. Because the frequency of the high-frequency driving square wave is much higher than the frequency of the load detection signal square wave, the total energy difference between the current pulses generated by the two is significant. Through the combined action of the third MOS transistor Q3 and the fourth capacitor C4, the load detection signal's pulse current has a negligible effect on the charge of the second capacitor C2. In other words, the bidirectional switch's shutdown behavior is unrelated to the load detection behavior.

[0133] 3. Detection and drive decoupling:

[0134] When the load status needs to be detected, the MCU outputs a high level, and the driving signal stops without affecting the detection signal.

[0135] In the embodiment of the present invention, the same signal transformer T1 transmits both the driving signal and the detection signal, and the two signals do not affect each other. Therefore, the circuit of the embodiment of the present invention realizes the multiplexing of the driving and detection signals.

[0136] An embodiment of the present invention further provides a device for isolating, driving, and detecting a bidirectional switch, including the circuit described above.

[0137] In addition, other structures and functions of the device according to the embodiment of the present invention are known to those skilled in the art and are not described here in detail to reduce redundancy.

[0138] It should be noted that the logic and / or steps represented in flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic device), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and a portable compact disc read-only memory (CDROM). Furthermore, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing it in another suitable manner if necessary, and then storing it in a computer memory.

[0139] It should be understood that various components of the present invention may be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods may be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof may be used: a discrete logic circuit having logic gate circuits for implementing logic functions on data signals, an application-specific integrated circuit having suitable combinational logic gate circuits, a programmable gate array (PGA), a field-programmable gate array (FPGA), etc.

[0140] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0141] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0142] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0143] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0144] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0145] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A circuit for isolating driving and detecting a bidirectional switch, characterized in that: include: A first circuit, comprising a switch driving circuit, a driving signal detection circuit, and a bidirectional switch coupled in sequence; a second circuit, the second circuit comprising a load access signal detection circuit, a high-order harmonic generation circuit, and a load coupled in sequence; the load is coupled to the bidirectional switch; a decoupling circuit, wherein a first end of the decoupling circuit is coupled to the switch driving circuit and the driving signal detection circuit respectively; a second end of the decoupling circuit is coupled to the load access signal detection circuit and the high-order harmonic generation circuit respectively; The load is connected to a signal detection circuit, comprising: The first triode and signal transformer; The collector of the first transistor is coupled to the GPIO, the emitter of the first transistor is grounded, and the base of the first transistor is coupled to the same-name terminal of the primary coil of the signal transformer; The decoupling circuit comprises: The third MOS tube; The gate of the third MOS transistor is coupled to the opposite-name end of the secondary coil of the signal transformer, the source of the third MOS transistor is coupled to the same-name end of the secondary coil of the signal transformer; and the drain of the third MOS transistor is coupled to the drive signal detection circuit.

2. The circuit for isolating driving and detecting a bidirectional switch according to claim 1, characterized in that: The load is connected to the high-order harmonic generating circuit; The high-order harmonic generating circuit sends the high-order harmonics to the signal transformer and turns on the first transistor.

3. The circuit for isolating driving and detecting a bidirectional switch according to claim 1, characterized in that: The switch driving circuit includes: Second triode; The base of the second transistor is coupled to the GPIO, the emitter of the second transistor is coupled to VCC, and the collector of the second transistor is coupled to the same-name terminal of the primary coil of the signal transformer.

4. The circuit for isolating driving and detecting a bidirectional switch according to claim 3, characterized in that: The GPIO sends the high-frequency carrier to the signal transformer through the second transistor.

5. The circuit for isolating driving and detecting a bidirectional switch according to claim 1, characterized in that: The decoupling circuit further includes: A fourth capacitor, wherein a first end of the fourth capacitor is coupled to the opposite-name end of the secondary coil of the signal transformer, and a second end of the fourth capacitor is coupled to a power supply.

6. The circuit for isolating driving and detecting a bidirectional switch according to claim 5, characterized in that: The high-order harmonic generating circuit comprises: a seventh triode, an eighth triode, a ninth triode, a tenth triode, and an eleventh triode; The emitter of the seventh transistor is coupled to the emitter of the eighth transistor and the same-name terminal of the secondary coil of the signal transformer respectively, the base of the seventh transistor is coupled to the power supply, and the collector of the seventh transistor is coupled to the collector of the tenth transistor; The emitter of the eighth transistor is coupled to the same-name terminal of the secondary coil of the signal transformer, the base of the eighth transistor is coupled to the bidirectional switch and the load respectively, and the collector of the eighth transistor is coupled to the collector of the eleventh transistor; The collector of the ninth transistor is coupled to the same-name terminal of the secondary coil of the signal transformer; the emitter of the ninth transistor is coupled to the emitter of the tenth transistor and the emitter of the eleventh transistor respectively; The emitter of the tenth transistor is coupled to the emitter of the eleventh transistor, and the base of the tenth transistor is coupled to the base of the eleventh transistor.

7. The circuit for isolating driving and detecting a bidirectional switch according to claim 1, characterized in that: The driving signal detection circuit includes: A second capacitor, wherein a first end of the second capacitor is coupled to the drain of the third MOS tube; and a second end of the second capacitor is coupled to the bidirectional switch and the load respectively.

8. A device for isolating driving and detecting a bidirectional switch, characterized in that: The method comprises the circuit according to any one of claims 1 to 7.

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