A forced-guided relay control device and control method

Abstract

The application discloses a kind of forced direction type relay control device and control method, device includes: input DC voltage source, electronic switch, first central processing unit, second central processing unit and transistor controllable coil voltage adjustment circuit, the input DC voltage source is connected the transistor controllable coil voltage adjustment circuit by the electronic switch;The transistor controllable coil voltage adjustment circuit is regulated by the on-off of internal transistor input voltage from the input DC voltage source, generates output voltage and supplies the coil of forced direction type relay, the first central processing unit generates PWM signal for transistor controllable coil voltage adjustment circuit, and the sampling voltage of output voltage and the state of a normally closed contact of forced direction type relay are back sampled.This application makes that the on-off of relay coil is controlled by double CPU redundancy, can reduce the heating of relay coil, energy saving low carbon is simultaneously and prolongs the life of entire whole electronic product, improves user experience.

Description

Technical Field

[0001] This invention relates to the field of rail transit control technology, and in particular to a forced-guided relay control device and control method. Background Technology

[0002] In recent years, the application of fully electronic interlocking products in the railway industry has been increasing year by year. Forced-type guide relays are widely used in fully electronic interlocking products, typically found on turnout machine hardware control circuit boards, signal light hardware control circuit boards, and discrete input / output hardware control circuit boards. The higher the density of a single circuit board and the more relays used, the lower the relative cost. Forced-type guide relays rely on energizing / de-energizing their coils to control the opening / closing of normally closed contacts. Energizing the coils causes heat generation. When a large number of relays are used, the simultaneous energization of all relays leads to increased coil heating, resulting in a higher overall internal temperature rise and reduced product lifespan.

[0003] The common control method for forced-direction relays used on existing fully electronic circuit boards is as follows: the CPU (Central Processing Unit) controls the on / off state of the primary side of an optocoupler, and the secondary side controls the on / off state of an electronic switch. The electronic switch is connected in series with the coil of the forced-direction relay and the coil control power supply. The coil control power supply is a constant voltage source. When the optocoupler is open, the coil control power supply flows through the coil, energizing the normally open contacts of the relay, causing them to close. Because the control power supply is a constant voltage source, and the voltage is generally controlled at the rated operating voltage of the relay coil, the relay heats up relatively evenly after being energized. The operating voltage of a typical forced-direction relay consists of a pull-in voltage, a holding voltage, and a release voltage. That is, when the voltage through the coil is greater than the pull-in voltage, the relay can switch from the released state to the pulled-in state. Once the relay is pulled in, it can remain in the pulled-in state as long as the voltage is greater than the holding voltage, until the voltage is less than the release voltage, at which point the relay will release. Generally, the holding voltage is much lower than the pull-up voltage. Many manufacturers' relays have a holding voltage of less than or equal to half of the rated voltage. However, in order to ensure that the relay can be pulled up smoothly, the voltage is kept constant at the rated voltage. This causes the relay to heat up at a relatively high level, which becomes an obstacle to increasing the board density and is not conducive to cost control and energy saving and low carbon requirements. Summary of the Invention

[0004] The purpose of this invention is to provide a forced-guided relay control device that can reduce relay coil heating, save energy and reduce carbon emissions, while extending the life of the entire electronic product and improving the user experience.

[0005] The technical solution to achieve the above objectives is:

[0006] A forced-guided relay control device includes: an input DC voltage source, an electronic switch, a first central processing unit, a second central processing unit, and a transistor-controlled coil voltage adjustment circuit.

[0007] The input DC voltage source is connected to the transistor controllable coil voltage adjustment circuit via the electronic switch;

[0008] The transistor-controlled coil voltage adjustment circuit regulates the input voltage from the input DC voltage source by switching the internal transistor on and off, and generates an output voltage to supply the coil of the forced-direction relay.

[0009] The first central processing unit generates a PWM (pulse width modulation) signal for controlling the switching of the transistor and transmits it to the transistor controllable coil voltage adjustment circuit. On the other hand, it samples the output voltage and the state of a normally closed contact of a forced-guided relay.

[0010] The second central processing unit controls the on / off state of the electronic switch on one hand, and monitors the PWM signal generated by the first central processing unit and the state of another normally closed contact of the forced-guided relay on the other hand.

[0011] Preferably, the coils of both the transistor-controlled coil voltage adjustment circuit and the forced-guided relay are grounded.

[0012] Preferred options also include:

[0013] A first resistor connected between the first central processing unit and the transistor-controlled coil voltage adjustment circuit to mitigate the overshoot and overshoot of the PWM signal; and

[0014] A second resistor is connected between the output of the first central processing unit and the second central processing unit.

[0015] Preferably, it further includes: a third resistor and a fourth resistor for dividing and sampling the output voltage to obtain a sampled voltage.

[0016] One end of the third resistor is connected to the connection terminal of the transistor controllable coil voltage adjustment circuit and the coil of the forced-guided relay, and the other end is grounded through the fourth resistor;

[0017] The coil control voltage monitoring circuit is connected to the junction of the third and fourth resistors, and outputs the adjusted sampling voltage to the first central processing unit for reading.

[0018] Preferably, it further includes a diode connected in parallel with the coil of the forced-direction relay for providing freewheeling current to the coil of the forced-direction relay.

[0019] Preferred options also include:

[0020] A sixth resistor is provided to limit the current of the signal sampled by the normally closed contact of the first central processing unit and a forced-guided relay.

[0021] A fifth resistor is used to limit the current of the signal sampled from the second central processing unit and another normally closed contact of the forced-guided relay.

[0022] Preferably, the two normally closed contacts are powered by their respective DC power supplies.

[0023] Preferably, the first central processing unit (CPU) and the second CPU are connected via a local bus, and the first CPU and the second CPU are also connected to a host computer.

[0024] A control method for the aforementioned forced-guided relay control device includes:

[0025] Step 1: The first central processing unit configures the frequency and duty cycle of the PWM signal corresponding to the pick-up voltage and transmits it to the second central processing unit for recording;

[0026] Step two: When the second central processing unit reads that the frequency and duty cycle of the PWM signal sent by the first central processing unit are consistent with the values ​​it monitors, it issues a command to close the electronic switch and notifies the first central processing unit; if they are inconsistent, the second central processing unit sends an error alarm to the first central processing unit and the host computer, and stops.

[0027] Step 3: After the first and second central processing units reach the stable engagement time of the forced-guided relay, they each sample the state of a normally closed contact. When both read a low level, it indicates that the relay has been stably engaged. At this point, step 4 can be skipped to proceed to step 5; otherwise, step 4 must be entered and subsequent operations must be stopped after step 4 is completed.

[0028] Step four: The first central processing unit acquires the sampled voltage and transmits it to the second central processing unit and the host computer;

[0029] Step 5: The first central processing unit configures the frequency and duty cycle of the PWM signal corresponding to the holding voltage and sends it to the second central processing unit. After the first central processing unit receives the response information known to the second central processing unit, it outputs the PWM signal.

[0030] Step six: The first and second central processing units each retrieve the state of a normally closed contact. If both read a low level, proceed to step eight after completing step seven; otherwise, after completing step seven, send an error alarm to the host computer and stop.

[0031] Step 7: The first central processing unit (CPU) acquires the sampled voltage and determines whether it is within the preset range. At the same time, it transmits the sampled voltage value and the determination result to the second CPU and the host computer. The second CPU reads the frequency and duty cycle of the PWM signal sent by the first CPU and compares it with the value it monitors. It then sends the comparison result to the first CPU and the host computer.

[0032] Step 8: The host computer checks whether the sampled voltage is within the preset range. If it exceeds the range, it sends a command to the first central processing unit to stop issuing PWM and simultaneously sends a command to the second central processing unit to turn on the electronic switch. At the same time, the host computer checks whether the frequency and duty cycle of the PWM signal are consistent with the monitored values. If they are inconsistent, it sends a command to the first central processing unit to stop issuing PWM and simultaneously sends a command to the second central processing unit to turn on the electronic switch. If the sampled voltage is within the range and the monitored values ​​of PWM frequency and duty cycle are consistent with the preset values, then steps 6 and 7 are repeated periodically.

[0033] Preferably, in step two, the second central processing unit compares the frequency and duty cycle of the PWM signal sent by the first central processing unit with the values ​​it has monitored multiple times.

[0034] In step three, within a preset time period, the first central processing unit and the second central processing unit each retrieve a normally closed contact state.

[0035] In step six, within a preset time period, the first central processing unit and the second central processing unit each retrieve a normally closed contact state.

[0036] In step seven, the first central processing unit (CPU) repeatedly samples and compares the voltage with a preset range; the second CPU compares the frequency and duty cycle of the PWM signal sent by the first CPU with the values ​​it has monitored multiple times.

[0037] The beneficial effects of this invention are as follows: This invention enables redundant dual-CPU control of the relay coil's on / off state. The control power supply voltage of the relay coil is adjustable, providing the required pull-up voltage at the moment of coil activation. Once the relay stabilizes, the duty cycle or frequency of the PWM wave can be adjusted to maintain the voltage at the required holding voltage. The power consumption of the relay coil is nearly one-third that of commonly used existing control methods. Since heat generation is proportional to power consumption, the heat generation of a single relay coil is significantly reduced, which helps to increase the power density of the circuit board, save energy and reduce carbon emissions, and lower the cost of the entire electronic product.

[0038] The relay status is monitored by dual CPUs. The control commands for the relays are compared with the monitored status by the dual CPUs. If either CPU fails to match the data, the power supply to the relay coil can be disconnected independently, causing the relay to drop and the system to switch to a safer position. This is safer and more reliable than a single CPU-controlled relay activation and deactivation scheme.

[0039] This invention not only monitors the status of relay contacts, but also collects the magnitude of the control voltage of the relay coil and the frequency and duty cycle of the PWM that adjusts the magnitude of the control voltage of the coil. When a fault occurs, it is convenient to accurately locate the fault and improve maintainability. Attached Figure Description

[0040] Figure 1 This is a structural diagram of the forced-guided relay control device of the present invention. Detailed Implementation

[0041] The invention will now be further described with reference to the accompanying drawings.

[0042] Please see Figure 1 The forced-guided relay control device of the present invention includes: an input DC voltage source VCC1, an electronic switch S1, a first central processing unit 100, a second central processing unit 200, and a transistor controllable coil voltage adjustment circuit 300.

[0043] The input DC voltage source VCC1 is connected to the transistor-controlled coil voltage adjustment circuit 300 via electronic switch S1. Electronic switch S1 controls the on / off state of the power supply to the input DC voltage source VCC1.

[0044] The transistor-controlled coil voltage adjustment circuit 300 regulates the input voltage from the input DC voltage source VCC1 by switching the internal transistor on and off, and generates an output voltage VCC2 to supply the coil of the forced-direction relay K1.

[0045] The first central processing unit 100 generates a PWM signal for controlling the switching of transistors and transmits it to the transistor controllable coil voltage adjustment circuit 300. On the other hand, it samples the output voltage VCC2 and the state of a normally closed contact of the forced-guided relay K1.

[0046] The second central processing unit 200 controls the on / off state of the electronic switch S1 on one hand, and monitors the PWM signal generated by the first central processing unit 100 and the state of the other normally closed contact of the forced-guided relay K1 on the other hand. The control terminal of the electronic switch S1 is connected to the second central processing unit 200.

[0047] In this embodiment, the resistors also include a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6.

[0048] The coils of the transistor-controlled coil voltage adjustment circuit 300 and the forced-guided relay K1 are both grounded.

[0049] The first resistor R1 is connected between the first central processing unit 100 and the transistor-controlled coil voltage adjustment circuit 200 to reduce the overshoot and overshoot of the PWM signal. The second resistor R2 is connected between the output of the first central processing unit 100 and the second central processing unit 200 for isolation of the dual-CPU power supply system.

[0050] The third resistor R3 and the fourth resistor R4 are connected in series. R4 is used to divide and sample the output voltage VCC2 to obtain the sampled voltage. Specifically, one end of the third resistor R3 is connected to the connection terminal of the transistor controllable coil voltage adjustment circuit 300 and the coil of the forced-guided relay K1, and the other end is grounded through the fourth resistor R4.

[0051] The coil control voltage monitoring circuit 400 is connected to the junction of the third resistor R3 and the fourth resistor R4, and outputs the sampled voltage after adjustment to the first central processing unit 100 for reading.

[0052] Diode D1 is connected in parallel with the coil of the forced-direction relay K1 to provide freewheeling current to the coil of the forced-direction relay K1. When the coil of the forced-direction relay K1 is de-energized, energy can be released through diode D1.

[0053] The sixth resistor R6 is connected to one normally closed contact of the first central processing unit 100 and the forced-guided relay K1, and is used to limit the current of the signal sampled by that normally closed contact. The fifth resistor R5 is connected to the other normally closed contact of the second central processing unit 200 and the forced-guided relay K1, and is used to limit the current of the signal sampled by that normally closed contact. The two normally closed contacts are powered by their respective DC power supplies VDD1 and VDD2.

[0054] The first central processing unit 100 and the second central processing unit 200 are connected via a local bus. The first central processing unit 100 and the second central processing unit 200 are also connected to a host computer.

[0055] The voltage from the input DC voltage source VCC1, after passing through electronic switch S1, generates an output voltage VCC2 through the transistor-controlled coil voltage adjustment circuit 300. The output voltage VCC2 directly supplies the coil of the forced-direction relay K1. The PWM signal controlling the transistor's on / off state is generated by the first central processing unit 100. The first central processing unit 100 adjusts the magnitude of the second central processing unit 200 by controlling the frequency and duty cycle of the PWM signal. The PWM signal generated by the first central processing unit 100 passes through the first resistor R1 and is sent to the transistor-controlled coil voltage adjustment circuit 300 to control the transistor's on / off state. Simultaneously, it passes through the second resistor R2 and is sent to the second central processing unit 200 for monitoring. The output voltage VCC2 is sampled and divided by the third resistor R3 and the fourth resistor R4, then sent to the coil control voltage monitoring circuit 400 for isolation and voltage adjustment before being sent to the analog-to-digital converter pin of the first central processing unit 100. Thus, the first central processing unit 100 can monitor the magnitude of the output voltage VCC2 in real time. One normally closed contact of the forced-guided relay K1 is connected to a DC power supply VDD1 at one end, and the other end is connected to a pin of the first central processing unit 100 through a sixth resistor R6, so that the activated or deactivated state of the forced-guided relay K1 is detected by the first central processing unit 100; one normally closed contact of the forced-guided relay K1 is connected to a DC power supply VDD2 at one end, and the other end is connected to a pin of the second central processing unit 200 through a fifth resistor R5, so that the activated or deactivated state of the forced-guided relay K1 is detected by the second central processing unit 200.

[0056] The first central processing unit 100 and the second central processing unit 200 can communicate with each other via a local bus. The second central processing unit 200 can then inform the first central processing unit 100 of the on / off commands for the control electronic switch S1, the retrieval status of the normally closed contacts of the forced-guided relay K1, and the monitored PWM wave frequency and duty cycle. Similarly, the first central processing unit 100 can inform the second central processing unit 200 of its preset PWM wave frequency and duty cycle, the retrieval status of the normally closed contacts of the forced-guided relay K1, and the read-back coil control voltage feedback value. Based on this information, both CPUs can determine whether the control commands and retrieval status of the forced-guided relay K1 are consistent. If any inconsistency is found, both the first central processing unit 100 and the second central processing unit 200 can disconnect the input DC voltage source VCC1 from the coil of the forced-guided relay K1, thereby de-energizing and causing the forced-guided relay K1 to drop.

[0057] Through this invention, when the forced-guided relay K1 transitions from a de-energized to an energized state, the first central processing unit 100 can set the frequency and duty cycle to generate a voltage VCC2 greater than or equal to the pull-in voltage. Once the forced-guided relay K1 is stably engaged and both CPUs are sampling normally, the first central processing unit 100 can adjust the duty cycle to reduce the coil voltage of the forced-guided relay K1, only needing to maintain a voltage VCC2 greater than or equal to the holding voltage. Since the holding voltage of a typical forced-guided mutual exclusion relay coil is much lower than its pull-in voltage, and coil heating is proportional to voltage, this invention can reduce the heating of a single relay coil for relays requiring long-term engagement. This allows for increased density of the all-electronic single board, reducing costs while saving energy and reducing carbon emissions.

[0058] In this embodiment, the electronic switch S1 can be a common PhotoMOS or P-MOSFET device. The first central processing unit 100 and the second central processing unit 200 can be any control chip such as ARM, PowerPC, or FPGA. The coil control voltage monitoring circuit 400 can be a voltage adjustment circuit constructed using common operational amplifiers. The diode D1 is selected as a diode that can withstand the reverse voltage of the relay coil. The first resistor R1 can be a common surface mount resistor. The second resistor R2 can be a metal film resistor. The third resistor R3, the fourth resistor R4, the fifth resistor R5, and the sixth resistor R6 can be common surface mount resistors. The transistor-controlled coil voltage adjustment circuit 300 can be a common buck circuit where the output voltage is controlled by a transistor, or a negative charge pump circuit composed of a push-pull circuit. The magnitude of the output voltage VCC2 can be adjusted by controlling the switching on and off of the transistor.

[0059] When electronic switch S1 is open, the coil of the forced-guided relay K1 is de-energized, and K1 drops, meaning its normally open contact opens and its normally closed contact closes. When electronic switch S1 is closed, the input voltage VCC1 of the transistor controllable coil voltage adjustment circuit 300 is a necessary condition for the coil of the forced-guided relay K1 to be energized.

[0060] The control method for the aforementioned forced-guided relay control device includes the following steps:

[0061] Step 1: The first central processing unit 100 configures the frequency and duty cycle of the PWM signal corresponding to the pick-up voltage and transmits it to the second central processing unit 200 for recording.

[0062] Step 2: When the second central processing unit 200 reads that the frequency and duty cycle of the PWM signal sent by the first central processing unit 100 are consistent with the values ​​it monitors, it issues a command to close the electronic switch S1 and notifies the first central processing unit 100; if they are inconsistent (a few errors are allowed, which can be set according to system needs), the second central processing unit 200 sends an error alarm to the first central processing unit 100 and the host computer, and stops.

[0063] Step 3: After the first CPU 100 and the second CPU 200 reach the stable engagement time of the forced-guided relay K1, they each sample the state of a normally closed contact. When both read a low level (fault tolerance allowed, within a preset time), it indicates that the relay has stably engaged. At this point, step 4 can be skipped, and step 5 can be proceeded. If the first CPU 100 and the second CPU 200 exceed the fault tolerance range, and one CPU reads a high level or both CPUs read a high level, it is determined that the relay engagement has failed. In this case, step 4 must be entered, and subsequent operations must be stopped after completing step 4.

[0064] Step 4: The first central processing unit 100 collects the sampled voltage and transmits it to the second central processing unit 200 and the host computer for monitoring or fault location.

[0065] Step 5: The first central processing unit 100 configures the frequency and duty cycle of the PWM signal corresponding to the holding voltage and sends it to the second central processing unit 200. After the first central processing unit 100 receives the known response information from the second central processing unit 200, it outputs the PWM signal.

[0066] Step six: The first central processing unit 100 and the second central processing unit 200 each sample the state of a normally closed contact. When both read a low level (fault tolerance is allowed within a preset time), it indicates that the relay is stably energized. After completing step seven, proceed to step eight; otherwise, after completing step seven, send an error alarm to the host computer and stop.

[0067] Step 7: The first central processing unit 100 collects the sampled voltage (which may be sampled multiple times) and determines whether it is within the preset range. At the same time, it transmits the sampled voltage value and the determination result to the second central processing unit 200 and the host computer. The second central processing unit 200 reads the frequency and duty cycle of the PWM signal sent by the first central processing unit 100, compares it with the value it monitors, and sends the comparison result to the first central processing unit 100 and the host computer.

[0068] Step 8: The host computer checks whether the sampled voltage is within the preset range. If it exceeds the range, it sends a command to the first central processing unit 100 to stop issuing PWM, and at the same time sends a command to the second central processing unit 200 to turn on the electronic switch. Simultaneously, the host computer checks whether the frequency and duty cycle of the PWM signal are consistent with the monitored values. If they are inconsistent, it sends a command to the first central processing unit 100 to stop issuing PWM, and at the same time sends a command to the second central processing unit 200 to turn on the electronic switch. If the sampled voltage is within the range, and the monitored values ​​of the PWM frequency and duty cycle are consistent with the preset values, then steps 6 and 7 are repeated periodically.

[0069] The first central processing unit 100 and the second central processing unit 200 can periodically sample the state of the normally closed contact of the forced-guided relay K1 to monitor whether the state of K1 is consistent with the command in real time. When either CPU detects a discrepancy, it can independently disconnect the control power to the coil of the forced-guided relay K1, causing it to de-energize and fall. The first central processing unit 100 can be configured to have a PWM wave duty cycle of 0, so that VCC2 can still be adjusted to 0 even when the electronic switch S1 is closed. The second central processing unit 200 can issue a command to disconnect the electronic switch S1, so that even if the PWM is still outputting normally, the output voltage VCC2 can still be made to 0 even if the input voltage VCC1 is lost.

[0070] The control power supply voltage of the relay coil is adjustable. It provides the required pull-up voltage at the moment of energization, and once the relay stabilizes, the duty cycle or frequency of the PWM signal can be adjusted to maintain the voltage at the required holding voltage. Since the time from relay energization to stabilization is very short, typically only tens of milliseconds, far less than the relay's stable energization time, and the holding voltage of most manufacturers' forced-guided relays is generally much lower than the pull-up voltage, for example, Tektronix's SR4D4012 has a pull-up voltage of 9VDC, a holding voltage of 5.4VDC, and a rated voltage of 12VDC. Existing control methods often use a holding margin, setting the control coil's power supply voltage to a constant 12VDC. This invention allows setting the pull-up voltage to 12VDC and the holding voltage to 7V. Because the pull-up time is very short, it can be ignored. In this case, the power consumption of the relay coil using this invention's control method is nearly one-third that of the commonly used control methods. Since heat generation is proportional to power consumption, the heat generation of a single relay coil is greatly reduced, which helps improve the power density of the circuit board, saves energy and reduces carbon emissions, and lowers the cost of the entire electronic product.

[0071] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of the invention and should be defined by the claims.

Claims

1. A control method for a forced-guided relay control device, characterized in that, The forced-guided relay control device includes: an input DC voltage source, an electronic switch, a first central processing unit, a second central processing unit, and a transistor-controlled coil voltage adjustment circuit. The input DC voltage source is connected to the transistor controllable coil voltage adjustment circuit via the electronic switch; The transistor-controlled coil voltage adjustment circuit regulates the input voltage from the input DC voltage source by switching the internal transistor on and off, and generates an output voltage to supply the coil of the forced-direction relay. The first central processing unit generates a PWM signal for controlling the switching of the transistor and transmits it to the transistor controllable coil voltage adjustment circuit. On the other hand, it samples the output voltage and the state of a normally closed contact of a forced-guided relay. The second central processing unit controls the on / off state of the electronic switch on one hand, and monitors the PWM signal generated by the first central processing unit and the state of another normally closed contact of the forced-guided relay on the other hand. Also includes: A first resistor connected between the first central processing unit and the transistor-controlled coil voltage adjustment circuit to mitigate the overshoot and overshoot of the PWM signal; and A second resistor connected between the output of the first central processing unit and the second central processing unit; It also includes: a third resistor and a fourth resistor for dividing and sampling the output voltage to obtain a sampled voltage. One end of the third resistor is connected to the connection terminal of the transistor controllable coil voltage adjustment circuit and the coil of the forced-guided relay, and the other end is grounded through the fourth resistor; The coil control voltage monitoring circuit is connected to the junction of the third resistor and the fourth resistor, and outputs the adjusted sampling voltage to the first central processing unit for reading. Also includes: A sixth resistor is provided to limit the current of the signal sampled by the normally closed contact of the first central processing unit and the forced-guided relay. A fifth resistor is used to limit the current of the signal sampled by the normally closed contact of the second central processing unit and the forced-direction relay. Control methods include: Step 1: The first central processing unit configures the frequency and duty cycle of the PWM signal corresponding to the pick-up voltage and transmits it to the second central processing unit for recording; Step two: When the second central processing unit reads that the frequency and duty cycle of the PWM signal sent by the first central processing unit are consistent with the values ​​it monitors, it issues a command to close the electronic switch and notifies the first central processing unit; if they are inconsistent, the second central processing unit sends an error alarm to the first central processing unit and the host computer, and stops. Step 3: After the first and second central processing units reach the stable engagement time of the forced-guided relay, they each sample the state of a normally closed contact. When both read a low level, it indicates that the relay has been stably engaged. At this point, step 4 can be skipped to proceed to step 5; otherwise, step 4 must be entered and subsequent operations must be stopped after step 4 is completed. Step four: The first central processing unit collects the sampled voltage and transmits it to the second central processing unit and the host computer; Step 5: The first central processing unit configures the frequency and duty cycle of the PWM signal corresponding to the holding voltage and sends it to the second central processing unit. After the first central processing unit receives the response information known to the second central processing unit, it outputs the PWM signal. Step six: The first and second central processing units each retrieve the state of a normally closed contact. If both read a low level, proceed to step eight after completing step seven; otherwise, after completing step seven, send an error alarm to the host computer and stop. Step 7: The first central processing unit (CPU) acquires the sampled voltage and determines whether it is within the preset range. At the same time, it transmits the sampled voltage value and the determination result to the second CPU and the host computer. The second CPU reads the frequency and duty cycle of the PWM signal sent by the first CPU and compares it with the value it monitors. It then sends the comparison result to the first CPU and the host computer. Step 8: The host computer checks whether the sampled voltage is within the preset range. If it exceeds the range, it sends a command to the first central processing unit to stop issuing PWM and simultaneously sends a command to the second central processing unit to turn on the electronic switch. At the same time, the host computer checks whether the frequency and duty cycle of the PWM signal are consistent with the monitored values. If they are inconsistent, it sends a command to the first central processing unit to stop issuing PWM and simultaneously sends a command to the second central processing unit to turn on the electronic switch. If the sampled voltage is within the range and the monitored values ​​of PWM frequency and duty cycle are consistent with the preset values, then steps 6 and 7 are repeated periodically.

2. The control method of the forced-guided relay control device according to claim 1, characterized in that, The coils of both the transistor-controlled coil voltage adjustment circuit and the forced-guided relay are grounded.

3. The control method of the forced-guided relay control device according to claim 1, characterized in that, The forced-guided relay control device also includes a diode connected in parallel with the coil of the forced-guided relay for providing freewheeling current to the coil of the forced-guided relay.

4. The control method of the forced-guided relay control device according to claim 1, characterized in that, The two normally closed contacts are powered by their respective DC power supplies.

5. The control method of the forced-guided relay control device according to claim 1, characterized in that, The first and second central processing units are connected via a local bus and are also connected to a host computer.

6. The control method of the forced-guided relay control device according to claim 1, characterized in that, In step two, the second central processing unit compares the frequency and duty cycle of the PWM signal sent by the first central processing unit with the values ​​it has monitored multiple times. In step three, within a preset time period, the first central processing unit and the second central processing unit each retrieve a normally closed contact state. In step six, within a preset time period, the first central processing unit and the second central processing unit each retrieve a normally closed contact state. In step seven, the first central processing unit (CPU) repeatedly samples and compares the voltage with a preset range; the second CPU compares the frequency and duty cycle of the PWM signal sent by the first CPU with the values ​​it has monitored multiple times.

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