A relay drive circuit

Abstract

The application provides a relay driving circuit, which comprises a direct current bias voltage generating circuit, a base bias voltage generating circuit and a driving voltage generating circuit; the direct current bias voltage generating circuit is connected with the base bias voltage generating circuit, and is used for controlling a first optocoupler in the direct current bias voltage generating circuit to be turned on and outputting a direct current bias voltage after receiving a first driving signal; the base bias voltage generating circuit is connected with the driving voltage generating circuit, and is used for controlling a second optocoupler in the base bias voltage generating circuit to be turned on and generating a base bias voltage according to the direct current bias voltage after receiving a second driving signal; and the driving voltage generating circuit is used for controlling a first triode in the driving voltage generating circuit to be turned on according to the base bias voltage, and outputting a driving voltage to drive a relay, so that the relay can be controlled to be turned on or turned off through two driving signals, and the problem that the on-off control of the existing relay is realized through only one control signal and the safety factor is low is solved.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and more specifically to a relay drive circuit. Background Technology

[0002] With the continuous development of the transportation industry, my country's railway transportation lines are becoming increasingly dense, and the application scenarios of railway signaling products are becoming more and more complex.

[0003] In most railway signaling products, such as computer interlocking, relays are generally used as their safety execution units. However, current relay on / off control is generally achieved through only one control signal, resulting in a low safety factor. Summary of the Invention

[0004] To address this issue, this application provides a relay drive circuit to solve the problem that the on / off control of existing relays is achieved through only one control signal, resulting in a low safety factor.

[0005] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] The first aspect of this invention discloses a relay driving circuit, comprising: a DC bias voltage generating circuit, a base bias voltage generating circuit, and a driving voltage generating circuit; wherein:

[0007] The DC bias voltage generating circuit is connected to the base bias voltage generating circuit and is used to control the first optocoupler diode in itself to conduct and output DC bias voltage after receiving the first drive signal.

[0008] The base bias voltage generating circuit is connected to the driving voltage generating circuit, and is used to control the second optocoupler diode in itself to conduct after receiving the second driving signal, and generate the base bias voltage according to the DC bias voltage.

[0009] The drive voltage generating circuit is used to control the first transistor in itself to conduct according to the base bias voltage, and output a drive voltage to drive the relay.

[0010] Optionally, in the above-described relay drive circuit, the DC bias voltage generating circuit includes: a first resistor, a first optocoupler diode, a first anti-reverse current diode, a second resistor, a first transformer, a first rectifier bridge, a four-pin capacitor, and a third resistor; wherein:

[0011] One end of the first resistor receives the first drive signal; the other end of the first resistor is connected to the anode of the first optocoupler diode, the cathode of the first optocoupler diode is grounded, the collector of the first optocoupler diode is connected to one end of the second resistor and the cathode of the first anti-reverse current diode, the emitter of the first optocoupler diode is connected to the anode of the first anti-reverse current diode, and the connection point is connected to the negative terminal of the logic power supply.

[0012] The other end of the second resistor is connected to the first primary terminal of the first transformer, and the second primary terminal of the first transformer is connected to the positive terminal of the logic power supply; the first secondary terminal of the first transformer is connected to the second AC input terminal of the first rectifier bridge, and the second secondary terminal of the first transformer is connected to the first AC input terminal of the first rectifier bridge.

[0013] The negative output terminal of the first rectifier bridge is connected to the first negative terminal of the four-pin capacitor, and the positive output terminal of the first rectifier bridge is connected to the first positive terminal of the four-pin capacitor.

[0014] The second negative terminal of the four-pin capacitor is connected to one end of the third resistor; the second positive terminal of the four-pin capacitor is connected to the other end of the third resistor, and the connection point outputs the DC bias voltage.

[0015] Optionally, in the above-described relay drive circuit, the base bias voltage generating circuit includes: a fourth resistor, a second optocoupler diode, a fifth resistor, and a sixth resistor; wherein:

[0016] One end of the fourth resistor receives the second drive signal; the other end of the fourth resistor is connected to the anode of the second optocoupler diode, the cathode of the second optocoupler diode is grounded, the collector of the second optocoupler diode is connected to one end of the fifth resistor, and the other end of the fifth resistor receives the DC bias voltage; the emitter of the second optocoupler diode is connected to one end of the sixth resistor, and the connection point outputs the base bias voltage; the other end of the sixth resistor is connected to the negative terminal of the logic power supply.

[0017] Optionally, in the above-described relay drive circuit, the drive voltage generating circuit includes: a second transformer, a second rectifier bridge, a first transistor, a seventh resistor, a first capacitor, and a second capacitor; wherein:

[0018] The base of the first transistor receives the base bias voltage, the emitter of the first transistor is connected to one end of the seventh resistor and one end of the second capacitor, the other end of the seventh resistor and the other end of the second capacitor are both connected to the negative terminal of the logic power supply; the collector of the first transistor is connected to the first terminal of the primary of the second transformer, and the second terminal of the primary of the second transformer is connected to the positive terminal of the logic power supply.

[0019] The first terminal of the secondary winding of the second transformer is connected to the first AC input terminal of the second rectifier bridge, and the second terminal of the secondary winding of the second transformer is connected to the second AC input terminal of the second rectifier bridge.

[0020] The negative output terminal of the second rectifier bridge is connected to one end of the first capacitor, and the connection point serves as the output terminal of the driving voltage generation circuit, outputting the driving voltage; the positive output terminal of the second rectifier bridge is connected to the other end of the first capacitor.

[0021] Optionally, in the relay driving circuit described above, the driving voltage generating circuit further includes: a first transistor protection circuit for protecting the first transistor.

[0022] Optionally, in the above-mentioned relay driving circuit, the first transistor protection circuit includes: a second anti-reverse current diode; wherein, the cathode of the anti-reverse current diode is connected to the emitter of the first transistor, and the anode of the second anti-reverse current diode is connected to the collector of the first transistor.

[0023] Optionally, in the relay drive circuit described above, the drive voltage generating circuit further includes an inrush current absorption circuit for absorbing the inrush current generated at the primary terminals of the second transformer.

[0024] Optionally, in the above-mentioned relay drive circuit, the inrush current absorption circuit includes: a tenth resistor and a third capacitor;

[0025] Wherein, one end of the tenth resistor is connected to the second primary terminal of the second transformer, the other end of the tenth resistor is connected to one end of the third capacitor, and the other end of the third capacitor is connected to the first primary terminal of the second transformer.

[0026] Optionally, the relay drive circuit described above further includes a fast-drop control circuit, used to control the second transistor in itself to be turned off when the first drive signal and / or the second drive signal are not received, so as to make the drive voltage drop rapidly.

[0027] Optionally, in the above-mentioned relay drive circuit, the fast-drop control circuit includes: an eighth resistor, a ninth resistor, and a second transistor;

[0028] Wherein, one end of the eighth resistor is connected to the connection point between the negative output terminal of the second rectifier bridge and the second capacitor; the other end of the eighth resistor is connected to the base of the second transistor and one end of the ninth resistor respectively, the emitter of the second transistor is connected to the other end of the ninth resistor, and the connection point is connected to the connection point between the positive output terminal of the second rectifier bridge and the second capacitor; the collector of the second transistor outputs the driving voltage.

[0029] The relay driving circuit provided by this invention includes: a DC bias voltage generating circuit, a base bias voltage generating circuit, and a drive voltage generating circuit; wherein: the DC bias voltage generating circuit is connected to the base bias voltage generating circuit, and is used to control the first optocoupler diode in itself to conduct and output a DC bias voltage after receiving a first drive signal; the base bias voltage generating circuit is connected to the drive voltage generating circuit, and is used to control the second optocoupler diode in itself to conduct and generate a base bias voltage according to the DC bias voltage after receiving a second drive signal; the drive voltage generating circuit is used to control the first transistor in itself to conduct according to the base bias voltage and output a drive voltage to drive the relay. That is, the relay driving circuit provided by this application can realize the on / off control of the relay through two drive signals, solving the problem that the on / off control of the existing relay is realized through only one control signal, resulting in a low safety factor. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of a relay driving circuit provided in an embodiment of this application;

[0032] Figures 2 to 3 Circuit diagrams of two relay drive circuits provided in the embodiments of this application;

[0033] Figure 4 An impact waveform diagram provided for an embodiment of this application. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] This application provides a relay driving circuit to solve the problem that the on / off control of existing relays is achieved through only one control signal, resulting in a low safety factor.

[0036] Please see Figure 1 The relay drive circuit may include: a DC bias voltage generating circuit 101, a base bias voltage generating circuit 102, and a drive voltage generating circuit 103. Wherein:

[0037] The DC bias voltage generating circuit 101 is connected to the base bias voltage generating circuit 102. After receiving the first drive signal, it controls the first optocoupler diode in the DC bias voltage generating circuit 101 to turn on and output a DC bias voltage.

[0038] In practical applications, such as Figure 2 As shown, the DC bias voltage generating circuit 101 specifically includes: a first resistor RC1, a first optocoupler diode D1B, a first anti-reverse current diode V14, a second resistor R16, a first transformer T2, a first rectifier bridge A3, a four-pin capacitor C6, and a third resistor R20. Wherein:

[0039] One end of the first resistor RC1 receives the first drive signal CPU1; the other end of the first resistor RC1 is connected to the anode 3 of the first optocoupler diode D1B, the cathode 4 of the first optocoupler diode D1B is grounded, the collector 14 of the first optocoupler diode D1B is connected to one end of the second resistor R16 and the cathode of the first anti-reverse current diode V14, the emitter 13 of the first optocoupler diode D1B is connected to the anode of the first anti-reverse current diode V14, and the connection point is connected to the negative terminal of the logic power supply (024 in the figure).

[0040] The other end of the second resistor R16 is connected to the first terminal 2 of the primary winding of the first transformer T2. The second terminal 1 of the primary winding of the first transformer T2 is connected to the positive terminal of the logic power supply (+24 in the figure). The first terminal 4 of the secondary winding of the first transformer T2 is connected to the second AC input terminal 2 of the first rectifier bridge A3. The second terminal 3 of the secondary winding of the first transformer T2 is connected to the first AC input terminal 1 of the first rectifier bridge A3.

[0041] The negative output terminal 4 of the first rectifier bridge A3 is connected to the first negative terminal of the four-pin capacitor C6, and the positive output terminal 3 of the first rectifier bridge A3 is connected to the first positive terminal of the four-pin capacitor C6.

[0042] The second negative terminal of the four-pin capacitor C6 is connected to one end of the third resistor R20, and the second positive terminal of the four-pin capacitor C6 is connected to the other end of the third resistor R20. The connection point serves as the output terminal of the DC bias voltage generating circuit, which outputs a DC bias voltage.

[0043] It should be noted that the first negative terminal of the four-pin capacitor C6 is... Figure 2 The second negative terminal of the four-pin capacitor C6 is located at the top left port. Figure 2 At the lower left port, the first positive terminal of the four-pin capacitor C6 is... Figure 2 The upper right port of the four-pin capacitor C6 has its second positive terminal as... Figure 2 The bottom right port in the middle.

[0044] In practical applications, the first drive signal CPU1 can be a pulsating square wave signal, which can be generated by the upper-level control circuit of the relay drive circuit. Specifically, when the cathode 3 of the first optocoupler diode D1B receives the first drive signal, it controls itself to conduct. The primary winding of the first transformer T2 generates a corresponding pulse voltage, which is then transformed to the secondary winding of the first transformer T2. After rectification by the first rectifier bridge A3 and filtering by the four-pin capacitor C6, a stable DC bias voltage is output across the third resistor R20. In other words, this DC bias voltage can be generated by controlling the first optocoupler diode D1B with the first drive signal.

[0045] Specifically, the first rectifier bridge A3 can be a full-bridge rectifier bridge, and the first anti-reverse current diode V14 is used to provide anti-reverse current protection for the first optocoupler diode D1B.

[0046] The base bias voltage generating circuit 102 is connected to the drive voltage generating circuit 103, and is used to control the second optocoupler diode in the base bias voltage generating circuit 101 after receiving the second drive signal. Figure 2 When D1A is turned on, a base bias voltage is generated based on the DC bias voltage.

[0047] In practical applications, such as Figure 2 As shown, the base bias voltage generation circuit 102 may include: a fourth resistor RC2, a second optocoupler diode D1A, a fifth resistor R24, and a sixth resistor R28. One end of the fourth resistor RC2 receives the second drive signal CPU2; the other end of the fourth resistor RC2 is connected to the anode 1 of the second optocoupler diode D1A, the cathode 2 of the second optocoupler diode D1A is grounded, the collector 16 of the second optocoupler diode D1A is connected to one end of the fifth resistor R24, and the other end of the fifth resistor R24 ​​receives the DC bias voltage; the emitter 15 of the second optocoupler diode D1A is connected to one end of the sixth resistor R28, and the connection point outputs the base bias voltage; the other end of the sixth resistor R28 is connected to the negative terminal of the logic power supply (024 in the figure).

[0048] It should be noted that the second drive signal CPU2 can also be a pulsating square wave signal, which can also be generated by the upper-level control circuit of the relay drive circuit. When the cathode 2 of the second optocoupler diode D1A receives the second drive signal, it controls itself to conduct. The fifth resistor R24 ​​and the sixth resistor R28 form a DC bias voltage divider circuit, providing the base bias voltage for the first transistor V10 in the drive voltage generation circuit 103. Specifically, when the second optocoupler diode D1A is turned on, the branch between the voltage divider of the fifth resistor R24 ​​and the sixth resistor R28 is turned on, and the DC bias voltage is divided by the fifth resistor R24 ​​and the sixth resistor R28 to generate the base bias voltage, which is applied to the base of the first transistor V10. When the second optocoupler diode D1A is turned off, the branch between the fifth resistor R24 ​​and the sixth resistor R28 is turned off, the DC bias voltage cannot be divided by the fifth resistor R24 ​​and the sixth resistor R28 to generate the base bias voltage, and no voltage is applied to the base of the first transistor V10.

[0049] The drive voltage generation circuit 103 is used to control the first transistor in itself according to the base bias voltage. Figure 2 When V10 in the circuit is turned on, the output drive voltage is used to drive the relay.

[0050] In practical applications, such as Figure 2 As shown, the drive voltage generating circuit 103 may include: a second transformer T6, a second rectifier bridge A4, a first transistor V10, a seventh resistor R*2, a first capacitor C10, and a second capacitor C14. Specifically: the base B of the first transistor V10 receives the base bias voltage; the emitter E of the first transistor V10 is connected to one end of the seventh resistor R*2 and one end of the second capacitor C14; the other end of the seventh resistor R*2 and the other end of the second capacitor C14 are connected to the negative terminal of the logic power supply; the collector C of the first transistor V10 is connected to the first primary terminal of the second transformer T6; the second primary terminal of the second transformer T6 is connected to the positive terminal of the logic power supply. The first secondary terminal of the second transformer T6 is connected to the first AC input terminal 1 of the second rectifier bridge A4; the second secondary terminal of the second transformer T6 is connected to the second AC input terminal 2 of the second rectifier bridge A4. The negative output terminal 4 of the second rectifier bridge A4 is connected to one end of the first capacitor C10; this connection point serves as the output terminal of the drive voltage generating circuit 103, outputting the drive voltage. The positive output terminal 3 of the second rectifier bridge A4 is connected to the other end of the first capacitor C10.

[0051] It should be noted that the primary first terminal of the second transformer T6 is... Figure 2 Pin 1 in the diagram, the second terminal of the primary winding of the second transformer T6 is... Figure 2 In the middle, the first terminal of the secondary winding of the second transformer T6 is... Figure 2Pin 6 in the diagram, the second terminal of the secondary winding of the second transformer T6 is... Figure 2 Pin 10 in the middle.

[0052] It should be noted that when the base B of the first transistor V10 receives the base bias voltage, the first transistor V10 is turned on, and the primary winding of the second transformer T6 generates a voltage. After being transformed to the secondary winding of the second transformer T6, the voltage is rectified and filtered by the second rectifier bridge A4, and then filtered by the first capacitor C10 to output the drive voltage at the corresponding terminal of the first capacitor C10.

[0053] It should also be noted that the driving voltage supplies power to the freewheeling path of the corresponding coil in the relay. The relay driving circuit can output multiple driving voltages, each connected to the freewheeling path of the corresponding coil in the relay, for example... Figure 2 or Figure 3 The two driving voltages shown are ( Figure 2 XGH(Z) and XG(Z) in the text.

[0054] In practical applications, the same is true. Figure 2 or Figure 3 As shown, when the relay drive circuit has two drive voltage output terminals, a diode V6 can be connected in series at the drive voltage output terminal that is not equipped with the fast fall-back control circuit 104 to prevent current backflow on the relay coil.

[0055] It should be noted that the second capacitor C14 is connected in parallel across the seventh resistor R*2, mainly to increase the primary voltage of the second transformer T6 under pulsating conditions.

[0056] It should be noted that the pulsating state described in the embodiments of this application refers to the state when both the first driving signal and the second driving signal received by the relay driving circuit are pulsating square wave signals.

[0057] Based on the above principles, the relay driving circuit provided in this embodiment includes: a DC bias voltage generating circuit 101, a base bias voltage generating circuit 102, and a driving voltage generating circuit 103; wherein: the DC bias voltage generating circuit 101 is connected to the base bias voltage generating circuit 102, and is used to control the first optocoupler diode in itself to conduct after receiving the first driving signal, and output a DC bias voltage; the base bias voltage generating circuit 102 is connected to the driving voltage generating circuit 103, and is used to control the second optocoupler diode in itself to conduct after receiving the second driving signal, and generate a base bias voltage according to the DC bias voltage; the driving voltage generating circuit 103 is used to control the first transistor in itself to conduct according to the base bias voltage, and output a driving voltage to drive the relay. That is, the relay driving circuit provided in this application can realize the on / off control of the relay through two control signals, solving the problem that the on / off control of the existing relay is realized through only one control signal, resulting in a low safety factor.

[0058] It is worth noting that the relay drive circuit provided in this embodiment is a novel safety AND gate circuit, specifically designed for a 2-out-of-2 safety architecture. It can only output the relay drive voltage when both drive signals meet the required conditions. Furthermore, the relay drive circuit provided in this application uses optocouplers to receive the corresponding drive signals, employs an isolated digital square wave signal input method, and controls the drive voltage output through a transistor in the drive voltage generation circuit. This isolated output further enhances the control safety factor of the relay while meeting the requirements of railway signaling products.

[0059] Optionally, in another embodiment provided in this application, the driving voltage generating circuit 103 further includes an inrush current absorption circuit for absorbing the inrush current generated at the primary terminals of the second transformer T6.

[0060] Similarly, Figure 2 As shown, the surge current absorption circuit may include a tenth resistor R02 and a third capacitor C2. One end of the tenth resistor R02 is connected to the second primary terminal of the second transformer T6, and the other end of the tenth resistor R02 is connected to one end of the third capacitor C2. The other end of the third capacitor C2 is connected to the first primary terminal of the second transformer T6.

[0061] In practical applications, the tenth resistor R02 and the third capacitor C2, which are connected in series, can be connected across the primary winding of the second transformer T6 to release the energy stored in the primary winding of the second transformer T6 at the moment the first transistor V10 is turned off. The energy released from the primary winding of the second transformer T6 can be either through the tenth resistor R02 and the third capacitor C2 connected in parallel across the primary winding of the second transformer T6, or through the load current connected to the secondary winding of the second transformer T6.

[0062] Optionally, in another embodiment provided in this application, the driving voltage generating circuit 103 further includes a first transistor protection circuit for protecting the first transistor.

[0063] Similarly, Figure 2 As shown, the first transistor protection circuit may include: a second anti-reverse current diode V18; wherein, the cathode of the anti-reverse current diode V18 is connected to the emitter of the first transistor V10, and the anode of the second anti-reverse current diode V18 is connected to the collector of the first transistor V10.

[0064] In practical applications, the collector and emitter of the first transistor V10 can be protected by the second anti-reverse current diode V18.

[0065] It should be noted that this embodiment only shows the case where a second anti-reverse current diode V18 is used to protect the collector and emitter of the first transistor. However, in practical applications, multiple second anti-reverse current diodes V18 can also be connected in series to protect the collector and emitter of the first transistor V10, which is also within the scope of protection of this application.

[0066] Alternatively, in another embodiment provided in this application, such as Figure 2 As shown, the relay drive circuit also includes a fast-drop control circuit 104, which controls the second transistor V003 in itself to be cut off when no first drive signal or second drive signal is received, so as to make the drive voltage drop quickly.

[0067] Combination such as Figure 2 As shown, the fast fall-off circuit may include: an eighth resistor R003, a ninth resistor R004, and a second transistor V003; wherein, one end of the eighth resistor R003 is connected to the connection point between the negative output terminal of the second rectifier bridge A4 and the second capacitor C10; the other end of the eighth resistor R003 is connected to the base of the second transistor V003 and one end of the ninth resistor R004, the emitter of the second transistor V003 is connected to the other end of the ninth resistor R004, and the connection point is connected to the connection point between the positive output terminal of the second rectifier bridge A4 and the second capacitor C10; the collector of the second transistor V003 outputs a drive voltage.

[0068] In practical applications, when both the first and second drive signals stop transmitting square waves, it can be considered that neither the first nor the second drive signals have been received. After the two drive signals stop transmitting, it is desirable for the relay to drop as quickly as possible to ensure safety. Therefore, a fast-fallback circuit can be set at the output drive voltage port to achieve a rapid drop in the control drive voltage after the two drive signals stop transmitting, thus enabling the relay to drop as quickly as possible.

[0069] It should be noted that when the base current of the second transistor V003 in the fast fall-off circuit is sufficient to saturate and conduct the second transistor V003, the voltage drop between the collector and emitter of the second transistor V003 is very small. The presence of the second transistor V003 does not affect the drive voltage output by the drive voltage generation circuit. When any square wave stops, that is, after the first drive signal and / or the second drive signal stops, the first transistor V003 stops pulsating, the voltage across the first capacitor C10 drops to 0, the second transistor V003 is cut off, so there is no drive voltage output, blocking the freewheeling current conduction of the relay coil, thereby enabling the relay to achieve the fast fall-off function.

[0070] It should also be noted that since the fast-stop function is achieved by cutting off the freewheeling path of the relay coil, the relay coil will generate a back impulse voltage, which will be applied across the two ends of the second transistor V003.

[0071] It should be noted that, Figure 2 Taking the rapid drop of the drive voltage output from the connection point between the negative output terminal of the second rectifier bridge A4 and the second capacitor C10 as an example, in actual applications, if the connection point between the positive output terminal of the second rectifier bridge A4 and the second capacitor C10 also outputs a drive voltage, the same circuit can be used to control the rapid drop of the drive voltage output from the connection point between the positive output terminal of the second rectifier bridge A4 and the second capacitor C10.

[0072] Based on the relay drive circuit provided in the above embodiments, combined with Figure 3 Assuming this drive circuit is used to drive a 24V relay, to effectively improve the safety of railway signaling products and meet their safety requirements, the relay is designed as follows: Relay response time: intake delay 160ms, drop delay 70ms; Relay operating frequency: 3kHz~6kHz; Logic power supply voltage: typical 24V, range: 12~48V; Output voltage: under 24V power supply, typical value 24V, range: 5~36V adjustable; Drive power: under 24V power supply and 1700 ohm load, typical value 0.34W; maximum power 2W; maximum power consumption 0.8W. Then, the specific selection and values ​​of each component in this relay drive circuit can be as follows:

[0073] Since the output voltages across XG(Z) and XGH(Z) are known to be 24V, and considering the losses of diode V6, the peak value of the square wave input to rectifier bridge A4 must be greater than 25V. Therefore, transformer T6 must employ a step-up design. Assuming a 1:2 turns ratio step-up design for transformer T6, the specific process for selecting the primary resistor of transformer T6 can be as follows: The secondary resistor connected to the second transformer is a 1700Ω relay resistor connected in parallel with other resistor networks. These include resistors R003, R004, and R10. The impedance after parallel connection is approximately 1400Ω.

[0074] For transformer T6, the impedance seen from the primary winding is divided into two parts: one part is the resistance reflected from the secondary winding to the primary winding, and the other part is the inductive reactance of the primary inductance of transformer T6. These two parts, connected in parallel, constitute the primary impedance of transformer T6, R. 反射 =1400 / 4=350Ω. After determining the reflection resistance, in order to maintain the stability of the primary impedance of transformer T6, the primary inductive reactance R of transformer T6 is generally set to... L With reflection resistance R 反射 The relationship between R and R is: L ≥10·R 反射 Therefore, transformer T6 can be selected with a primary inductance > 300mH and R. L >5.6kΩ. At 3kHz, the primary impedance of transformer T6 is approximately 330Ω.

[0075] Selection of collector current value for transistor V10: Based on the minimum secondary voltage of transformer T6 being 26V, and the minimum primary voltage of transformer T6 being 13V under the condition that the transformer T6 turns ratio is 1:2, the minimum collector current of transistor V10 is I = 13 / 330 = 40mA.

[0076] Selection of emitter adjustment resistor R*2 and base bias voltage: When transistor V10 is turned on, the primary impedance of transformer T6 is related to the emitter adjustment resistor R*2 and the base bias voltage of transistor V10. ce This creates a voltage divider relationship with the 24V power supply. Based on the previous calculations, the primary voltage of transformer T6 must be greater than 13V. Assuming V... ceIf the base bias is 0, then the voltage across the emitter adjustment resistor R*2 should be less than 11V. The primary impedance of transformer T6 is 330Ω, therefore the emitter adjustment resistor R*2 should be less than 280Ω. Since the voltage across the emitter adjustment resistor R*2 is required to be less than 11V, and the voltage across R*2 is linked to its resistance, decreasing the resistance will correspondingly decrease the voltage. Otherwise, the collector current of transistor V10 will be too high, resulting in an excessively high output voltage that is difficult to adjust. Therefore, in this design, the base bias voltage of transistor V10 can be selected as 10V, the voltage across the emitter adjustment resistor R*2 as 9V, and the resistance of the emitter adjustment resistor R*2 as 210Ω.

[0077] The DC bias voltage is generated by the first drive signal (CPU1) controlled by optocoupler diode D1B. When the first drive signal generates a 5V, 3kHz square wave, optocoupler diode D1B is pulsatingly turned on, generating a 3kHz pulse voltage on the primary winding of transformer T2. After being converted to the secondary winding, the voltage is rectified by rectifier bridge A3 and filtered by capacitor C6, resulting in a stable DC bias voltage output across resistor R20. This DC bias voltage is then divided by resistors R24 and R28 to provide the base bias voltage for transistor V10. When optocoupler diode D1A is on, the base bias voltage is applied to the base of transistor V10 through resistors R24 and R28. When optocoupler diode D1A is off, there is no bias voltage at the base of transistor V10, and transistor V10 operates pulsatingly by switching optocoupler diode D1A on and off.

[0078] Transformer T2 serves as both an isolation and voltage transformer. Since the final output DC bias voltage is 10V, the secondary output voltage of transformer T2 must be greater than 11V (considering the voltage drop of rectifier A3). When the power supply voltage is 24V, transformer T2 can be designed as a step-up transformer or not. Assuming this design uses a step-up transformer, the turns ratio of transformer T2 is 1:2.

[0079] The function of resistor R16 is to adjust the amplitude of the base bias voltage. When optocoupler diode D1B is turned on, there is a voltage divider relationship between the primary impedance of transformer T2 and resistor R16. The secondary impedance of transformer T2 is approximately 4kΩ, which is the parallel connection of resistors R20, R24, and R28, and is reflected to the primary side of transformer T2 at 1kΩ. The function of resistor R16 is to adjust the primary voltage of transformer T2. When optocoupler diode D1A is turned on, there is a voltage divider relationship between resistor R16 and the primary impedance of transformer T2. When resistor R15 is 1.5kΩ, the primary voltage of transformer T2 is approximately 5.5V, which meets the voltage requirements of the subsequent stage.

[0080] The function of capacitor C6 is to filter the DC voltage after rectification by rectifier bridge A3. According to the formula: RC≥(3~5)T / 2, R≈2.8kΩ, T=1 / 3000S, C≥0.3uF. Considering that a larger capacitor C6 results in better filtering, this scheme selects a 10uF film capacitor as C6. Considering fault safety factors, capacitor C6 can be specifically selected as a four-pin capacitor. Because if capacitor C6 is open-circuited, and the secondary winding of optocoupler diode D1B breaks down, then regardless of whether optocoupler diode D1B is open, the transistor V10 can pulsately conduct. Resistor R20 serves as the load resistor after rectification, and has a voltage stabilizing effect.

[0081] Given that the output relay voltage is 24V, and subtracting the 1V voltage drop from the three diodes in the series circuit (including the two diodes in the rectifier bridge), the secondary voltage of transformer T6 is approximately 25V. Therefore, the primary voltage of transformer T6 needs to be 12.5V. By appropriately adjusting the value of the emitter adjustment resistor R*2, the collector current Ic of transistor V10 can be adjusted, thus achieving a primary voltage of 12.5V for transformer T6. Ic ≈ (Vb - 0.7) / R*2. The smaller the emitter adjustment resistor R*2, the larger the collector current Ic of transistor V10, resulting in a larger primary voltage of transformer T6 and a larger drive output voltage. Therefore, the emitter adjustment resistor R*2 can be used as a current adjustment resistor. The capacitor connected in parallel with the adjustment resistor increases the primary voltage of transformer T6 under pulsating conditions. The resistor R02 and capacitor C2 connected in parallel with the primary of transformer T6 absorb inrush current. At the instant transistor V10 is turned off, the energy stored in the primary winding of transformer T6 needs to be released. The release channels are the primary RC snubber circuit of transformer T6 and the load circuit of the secondary winding of transformer T6. The anti-reverse current diode V18 can be a 62V Zener diode, which protects the collector and emitter of transistor V10.

[0082] Resistors R003 and R004, along with transistor V003, constitute the fast-stop control circuit of the relay drive circuit. When both square waves are present, the pulsating voltage is rectified by rectifier bridge A4 and filtered by capacitor C10, outputting a DC 24V to drive the corresponding relay. Resistors R003 and R004 serve as bias resistors for transistor V003. When the base current of transistor V003 meets the condition Ib≈(24-0.7) / 10=2.33mA, transistor V003 is saturated and conducting. The Vce voltage drop of transistor V003 is very small, and the presence of transistor V003 does not affect the amplitude of the drive voltage. When either square wave stops, transistor V003 stops pulsating, and the voltage across capacitor C10 quickly drops to 0, thus cutting off transistor V003 and blocking the freewheeling path of the relay coil, thereby enabling the relay to achieve the fast-stop function. However, the fast-stop function is achieved by cutting off the freewheeling path of the relay coil. This causes the relay coil to generate a reverse impulse voltage, which is applied across transistor V003. The actual impulse waveform is as follows: Figure 4 As shown, the peak value is 83V.

[0083] It should be noted that the function of capacitor C10 is to filter the DC voltage after rectification by rectifier bridge A4. According to the formula RC≥(3~5)T / 2, R≈1.7kΩ, T=1 / 3000 S, C≥0.49uF, the capacitance value of capacitor C10 is selected as 10uF in this scheme.

[0084] It should also be noted that, Figure 3 The resistor R10, LED V2, anti-reverse current diode V22, optocoupler diode D3C, and resistor RH constitute a voltage feedback circuit used to detect the drive voltage of the control relay. When the relay drive voltage is higher than 12V, LED V2 lights up, optocoupler diode D3C turns on, and the feedback voltage on the secondary side of optocoupler diode D3C changes from high to low. When the relay drive voltage is higher than 18V, the secondary side of optocoupler diode D3C reaches saturation conduction, and the feedback voltage is less than 0.1V, which is a low level.

[0085] The features described in the various embodiments of this specification can be substituted for or combined with each other. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0086] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0087] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0088] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A relay drive circuit, characterized in that, include: DC bias voltage generation circuit, base bias voltage generation circuit and drive voltage generation circuit; The DC bias voltage generating circuit includes: a first resistor, a first optocoupler diode, a first anti-reverse current diode, a second resistor, a first transformer, a first rectifier bridge, a four-pin capacitor, and a third resistor; the base bias voltage generating circuit includes: a fourth resistor, a second optocoupler diode, a fifth resistor, and a sixth resistor; the drive voltage generating circuit includes: a second transformer, a second rectifier bridge, a first transistor, a seventh resistor, a first capacitor, and a second capacitor; wherein: The DC bias voltage generating circuit is connected to the base bias voltage generating circuit and is used to control the first optocoupler diode in itself to conduct and output DC bias voltage after receiving the first drive signal. The base bias voltage generating circuit is connected to the driving voltage generating circuit, and is used to control the second optocoupler diode in itself to conduct after receiving the second driving signal, and generate the base bias voltage according to the DC bias voltage. The driving voltage generating circuit is used to control the first transistor in itself to turn on according to the base bias voltage, and output driving voltage to drive the relay. The relay driving circuit further includes a fast-drop control circuit, which controls the second transistor in itself to be turned off when the first driving signal and / or the second driving signal are not received, so that the driving voltage drops quickly. The fast-drop control circuit includes: an eighth resistor, a ninth resistor, and a second transistor; Wherein, one end of the eighth resistor is connected to the connection point between the negative output terminal of the second rectifier bridge and the second capacitor; the other end of the eighth resistor is connected to the base of the second transistor and one end of the ninth resistor respectively, the emitter of the second transistor is connected to the other end of the ninth resistor, and the connection point is connected to the connection point between the positive output terminal of the second rectifier bridge and the second capacitor; the collector of the second transistor outputs the driving voltage.

2. The relay drive circuit according to claim 1, characterized in that, One end of the first resistor receives the first drive signal; the other end of the first resistor is connected to the anode of the first optocoupler diode, the cathode of the first optocoupler diode is grounded, the collector of the first optocoupler diode is connected to one end of the second resistor and the cathode of the first anti-reverse current diode, the emitter of the first optocoupler diode is connected to the anode of the first anti-reverse current diode, and the connection point is connected to the negative terminal of the logic power supply. The other end of the second resistor is connected to the first primary terminal of the first transformer, and the second primary terminal of the first transformer is connected to the positive terminal of the logic power supply; the first secondary terminal of the first transformer is connected to the second AC input terminal of the first rectifier bridge, and the second secondary terminal of the first transformer is connected to the first AC input terminal of the first rectifier bridge. The negative output terminal of the first rectifier bridge is connected to the first negative terminal of the four-pin capacitor, and the positive output terminal of the first rectifier bridge is connected to the first positive terminal of the four-pin capacitor. The second negative terminal of the four-pin capacitor is connected to one end of the third resistor; the second positive terminal of the four-pin capacitor is connected to the other end of the third resistor, and the connection point outputs the DC bias voltage.

3. The relay drive circuit according to claim 1, characterized in that, One end of the fourth resistor receives the second drive signal; the other end of the fourth resistor is connected to the anode of the second optocoupler diode, the cathode of the second optocoupler diode is grounded, the collector of the second optocoupler diode is connected to one end of the fifth resistor, and the other end of the fifth resistor receives the DC bias voltage; the emitter of the second optocoupler diode is connected to one end of the sixth resistor, and the connection point outputs the base bias voltage; the other end of the sixth resistor is connected to the negative terminal of the logic power supply.

4. The relay drive circuit according to claim 1, characterized in that... The base of the first transistor receives the base bias voltage, the emitter of the first transistor is connected to one end of the seventh resistor and one end of the second capacitor, the other end of the seventh resistor and the other end of the second capacitor are both connected to the negative terminal of the logic power supply; the collector of the first transistor is connected to the first terminal of the primary of the second transformer, and the second terminal of the primary of the second transformer is connected to the positive terminal of the logic power supply. The first terminal of the secondary winding of the second transformer is connected to the first AC input terminal of the second rectifier bridge, and the second terminal of the secondary winding of the second transformer is connected to the second AC input terminal of the second rectifier bridge. The negative output terminal of the second rectifier bridge is connected to one end of the first capacitor, and the connection point serves as the output terminal of the driving voltage generation circuit, outputting the driving voltage. The positive output terminal of the second rectifier bridge is connected to the other end of the first capacitor.

5. The relay drive circuit according to claim 4, characterized in that, The driving voltage generating circuit further includes a first transistor protection circuit for protecting the first transistor.

6. The relay drive circuit according to claim 5, characterized in that, The first transistor protection circuit includes: a second anti-reverse current diode; wherein the cathode of the anti-reverse current diode is connected to the emitter of the first transistor, and the anode of the second anti-reverse current diode is connected to the collector of the first transistor.

7. The relay drive circuit according to claim 4, characterized in that, The driving voltage generating circuit further includes an inrush current absorption circuit, used to absorb the inrush current generated at the primary terminals of the second transformer.

8. The relay drive circuit according to claim 7, characterized in that, The surge current absorption circuit includes: a tenth resistor and a third capacitor; Wherein, one end of the tenth resistor is connected to the second primary terminal of the second transformer, the other end of the tenth resistor is connected to one end of the third capacitor, and the other end of the third capacitor is connected to the first primary terminal of the second transformer.

Images