CN209962099U - Safety level switching value driving output control circuit - Google Patents
Safety level switching value driving output control circuit Download PDFInfo
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- CN209962099U CN209962099U CN201921267950.5U CN201921267950U CN209962099U CN 209962099 U CN209962099 U CN 209962099U CN 201921267950 U CN201921267950 U CN 201921267950U CN 209962099 U CN209962099 U CN 209962099U
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Abstract
The utility model discloses a security level switching value drive output control circuit, this control circuit includes: the device comprises a microprocessor, a transformer, a rectifying circuit, a filter circuit and a relay drive circuit; wherein the microprocessor generates a square wave signal to the transformer; the transformer transmits the square wave signal to the rectifying circuit, the rectifying circuit rectifies the square wave signal and then passes through the filter circuit, and the filtered signal is used for driving the relay driving circuit. The utility model can cope with the fault of the indefinite state after the IO port fault and the microprocessor program running away, etc., and can not cause the relay malfunction, thereby improving the reliability and the safety of the whole instrument control system (such as nuclear safety level DCS); just the utility model discloses a required peripheral device of control circuit is few, easily realizes.
Description
Technical Field
The invention relates to the technical field of safety level control, in particular to a safety level switching value driving output control circuit.
Background
The switching value driving output control is generally used for driving control equipment, and in some field control fields requiring high reliability, certainty and high safety, such as a nuclear power plant safety level instrument control system, a switching value output module is generally used for shutdown operation, and the switching value output of the switching value output module directly drives a shutdown circuit breaker to realize reactor core protection; the switching value output of the optimal module generally directly drives equipment such as a pump and a valve, and is a key link for realizing protection after an accident. At present, a DCS control system has been shifted from an analog technology to a digital technology, and a control module thereof has a CPU or an FPGA as a main processing chip, and the chip directly controls a relay to drive a field device. If a program problem occurs in a CPU or an FPGA or an IO pin of a drive output fails, the state of the output high or low level of an IO port of the drive output is indefinite, which easily causes a relay malfunction or a malfunction, and once the failure is not detected in time, the malfunction or the malfunction of a next-stage device is caused, which reduces the reliability and safety of the system.
The existing switching value driving output control circuit generally directly utilizes an IO port to drive a triode, utilizes the triode to drive the output of a relay, generally monitors whether the action state of a relay contact is consistent with the driving output state or not in order to improve the safety, and ensures the effectiveness of the current action. For example: the method comprises the steps that a Hall current sensor is installed on the contact side of an output relay, after a driving contact is closed, the Hall current sensor is used for carrying out current detection, a voltage signal is induced, and a CPU or an FPGA judges an IO port driving output signal and a withdrawn induced voltage signal so as to determine whether a driving output state is normal or not.
However, the monitoring of the action state of the relay contact and the action of the drive output state cannot ensure that the drive output of the relay is in a safe state under the condition of the fault of a CPU or an FPGA or the fault of a drive output IO port. For example: when a common cause fault occurs in a CPU or an FPGA, the control function of the CPU or the FPGA is lost, the output state of an IO port can be high level, low level and high configuration at random, and once the fault is high level, the next stage of equipment is mistakenly operated, so that a safety accident is caused.
Therefore, it is necessary to develop a switching value driving output circuit with high safety for the control field, and to ensure that the next stage of equipment is in a safe state in case of CPU or FPGA failure or IO port failure.
Disclosure of Invention
In order to solve the technical problems that the prior art has malfunction and cannot meet high safety and the like, the invention provides the safety-level switching value driving output control circuit for solving the problems.
The invention is realized by the following technical scheme:
a safety class switching value driving output control circuit, the control circuit comprising: the device comprises a microprocessor, a transformer, a rectifying circuit, a filter circuit and a relay drive circuit; wherein the microprocessor generates a square wave signal to the transformer; the transformer transmits the square wave signal to the rectifying circuit, the rectifying circuit rectifies the square wave signal and then passes through the filter circuit, and the filtered signal is used for driving the relay driving circuit.
The invention adopts the transformer to realize the transmission of the signals output by the I/O port of the microprocessor (FPGA or CPU), if the signals output by the I/O port of the microprocessor are normal signals (square wave signals), the signals can provide driving signals for a subsequent relay driving circuit through the transformer, and further control the action of the relay; if the I/O port of the microprocessor is in fault, the output signal of the I/O port of the microprocessor is a constant high level, a constant low level or a high resistance state signal, and the signals can not pass through a transformer, namely, a relay driving circuit does not have a driving signal, so that the action of a relay can not be controlled; the control circuit of the invention can effectively identify the fault of the I/O port of the microprocessor and simultaneously ensure that the subsequent relay contact can not be mistakenly operated to cause safety accidents. Similarly, the control circuit of the invention can also cope with common cause faults of the microprocessor, when the program of the microprocessor is abnormal, the frequency or the duty ratio of the signal generated by the I/O of the microprocessor exceeds the set range of the circuit, the voltage of the signal after rectification and filtering can not start the relay driving circuit, and the relay contact output is always in a safe state.
Preferably, in order to improve the control accuracy and reliability of the invention, the control circuit of the invention further comprises a current-limiting resistor and a protection circuit; the current-limiting resistor and the protection circuit are sequentially connected between the microprocessor and the transformer and used for protecting an I/O port of the microprocessor. Because the signal output by the I/O port of the microprocessor is a square wave signal, when the square wave signal is at a low level, the primary coil of the transformer generates a reverse transient induced voltage, and a protection circuit is required to absorb the transient induced voltage, thereby preventing the transient induced voltage from affecting subsequent circuits.
Preferably, the protection circuit comprises a protection diode, a protection capacitor and a protection resistor; the diode is connected in series with the protective capacitor and then connected in parallel with the protective resistor; the protection circuit is connected between the common connecting end of the current-limiting resistor and the transformer and the grounding end; and the protection circuit is connected with the primary side of the transformer in parallel.
Preferably, the protection diode is a schottky diode.
Preferably, the frequency and the duty ratio of the square wave signal output by the I/O port of the microprocessor are set according to the frequency of the transformer.
Preferably, the rectifier circuit is a half-wave rectifier circuit or a full-wave rectifier circuit, and is used for rectifying the secondary side voltage of the transformer.
Preferably, the filter circuit is an RC first-order low-pass filter circuit, and the signal rectified by the rectifier circuit is input into the filter circuit for smoothing filtering.
Preferably, the value of the parameter of the RC in the filter circuit is determined according to the frequency of the square wave signal.
Preferably, the relay driving circuit is a MOSFET, and the signal filtered by the filter circuit is input to a gate of the MOSFET to drive the relay to operate when the MOSFET is turned on.
Preferably, the transformer is a 1:1 transformer.
The invention has the following advantages and beneficial effects:
1. the invention mainly comprises a microprocessor, a transformer, a rectifying circuit and a filter circuit, wherein the transformer is used for transmitting energy of square wave signals sent by an IO port of the microprocessor, a diode is used for rectifying secondary side waveforms of the transformer, the filter circuit is used for shaping the waveforms, and finally the smooth filter voltage is used for driving a relay to act. The control circuit of the invention can deal with I/O port faults of a microprocessor (FPGA or CPU), when the faults of the IO port of the microprocessor are high level, low level or high resistance state, the circuit can not actively respond to the faults, and the relay contact output is always in a safe state; when the program of the microprocessor is abnormal, if the frequency or the duty ratio exceeds the range set by the circuit, the voltage after the shaping and filtering can not open the MOSFET, and the relay contact output is always in a safe state.
2. The circuit of the invention has simple realization mode, needs few peripheral devices, is easy to realize, can ensure that the next-stage equipment is in a safe state before the fault is artificially intervened when a microprocessor (FPGA or CPU) has the fault, reduces the misoperation rate of control equipment, improves the reliability and the safety of the whole instrument control system, and can be widely applied to the control field with high requirements on safety level, such as a nuclear power plant safety level digital instrument control system (DCS).
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
fig. 1 is a schematic block diagram of the circuit of the present invention.
Fig. 2 is a schematic circuit structure of the present invention.
Detailed Description
Hereinafter, the terms "include" or "may include" used in various embodiments of the present invention indicate the existence of the functions, operations or elements of the present invention, and do not limit the addition of one or more functions, operations or elements. Furthermore, as used in various embodiments of the present invention, the terms "comprises," "comprising," "includes," "including," "has," "having" and their derivatives are intended to refer only to the particular feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as first excluding the existence of, or adding to, one or more other features, numbers, steps, operations, elements, components, or combination of the foregoing.
In various embodiments of the present invention, the expression "or" at least one of a or/and B "includes any or all combinations of the words listed simultaneously. For example, the expression "a or B" or "at least one of a or/and B" may include a, may include B, or may include both a and B.
Expressions (such as "first", "second", and the like) used in various embodiments of the present invention may modify various constituent elements in various embodiments, but may not limit the respective constituent elements. For example, the above description does not limit the order and/or importance of the elements described. The foregoing description is for the purpose of distinguishing one element from another. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of various embodiments of the present invention.
It should be noted that: if it is described that one constituent element is "connected" to another constituent element, the first constituent element may be directly connected to the second constituent element, and a third constituent element may be "connected" between the first constituent element and the second constituent element. In contrast, when one constituent element is "directly connected" to another constituent element, it is understood that there is no third constituent element between the first constituent element and the second constituent element.
The terminology used in the various embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the various embodiments of the invention. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the present invention belong. The terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning that is consistent with their contextual meaning in the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein in various embodiments of the present invention.
To make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the following examples and drawings, and the exemplary embodiments and descriptions thereof of the present invention are only used for explaining the present invention, and are not intended as limitations of the present invention.
Example 1
The embodiment provides a safety level switching value driving output control circuit, which includes: the device comprises a microprocessor, a transformer, a rectifying circuit, a filter circuit and a relay drive circuit; as shown in fig. 1.
The microprocessor generates a square wave signal with fixed driving frequency and duty ratio, energy transmission is carried out on the square wave signal through the transformer, rectification is carried out through the rectifying circuit, waveform smoothing filtering is carried out through the filter circuit to generate grid driving voltage of the MOSFET, and the action of the relay is controlled.
In the embodiment, a transformer is adopted to transmit a signal output by an I/O port of a microprocessor (FPGA or CPU), and if the signal output by the I/O port of the microprocessor is a square wave signal (namely the signal is normally output by the microprocessor), the signal can provide a driving signal for a subsequent relay driving circuit through the transformer so as to control the action of a relay; if the I/O port of the microprocessor is in fault, the output signal of the I/O port of the microprocessor is a constant high level, a constant low level or a high resistance state signal, and the signals cannot pass through the transformer, namely, the relay driving circuit does not have a driving signal, so that the action of the relay cannot be controlled.
The control circuit of the embodiment can effectively identify the faults of the I/O port of the microprocessor, and simultaneously ensures that the subsequent relay contact cannot be mistakenly operated to cause safety accidents.
Similarly, the control circuit of the embodiment can also cope with common cause faults of the microprocessor, when the program of the microprocessor is abnormal, the frequency or the duty ratio of the signal generated by the I/O of the microprocessor exceeds the set range of the circuit, the voltage of the signal after rectification and filtering cannot start the relay driving circuit, and the relay contact output is always in a safe state.
In this embodiment, the frequency and duty ratio range of the square wave signal generated by the microprocessor is determined by the frequency range of the transformer.
In this embodiment, the transformer is preferably a 1:1 transformer with a small package.
Example 2
Based on the foregoing embodiment 1, this embodiment provides a safety-level switching value driving output control circuit, which further includes a current-limiting resistor and a protection circuit; as shown in fig. 2.
In this embodiment, the current-limiting resistor and the protection circuit are sequentially connected between the microprocessor and the transformer, and are configured to protect an I/O port of the microprocessor.
In this embodiment, the blocking of the current limiting resistor is determined by de-rating the maximum output current of the I/O port of the microprocessor; when the square wave signal of the primary coil of the transformer is at a low level, the coil can generate reverse transient induction voltage, a protection circuit is required to absorb the transient induction voltage, the influence of the transient induction voltage on a subsequent circuit is prevented, and the reliability and the safety of the control circuit are improved.
As shown in fig. 2, the protection circuit includes a protection diode, a protection capacitor, and a protection resistor; the diode is connected in series with the protective capacitor and then connected in parallel with the protective resistor; the protection circuit is connected between the common connecting end of the current-limiting resistor and the transformer and the grounding end; and the protection circuit is connected with the primary side of the transformer in parallel.
The switching time of the protection diode is a main consideration factor of the protection circuit, and the protection diode is preferably a Schottky diode; and the protection resistor and the protection capacitor are selected according to the actual current limiting condition.
In this embodiment, the rectifier circuit is a half-wave rectifier circuit or a full-wave rectifier circuit, and is configured to rectify the secondary voltage of the transformer. The rectification circuit is specifically selected according to the grid opening voltage of the rear-end drive circuit, and full-wave rectification is preferable if the grid opening voltage is higher, and half-wave rectification is preferable if the grid opening voltage is lower.
In this embodiment, the filter circuit is an RC first-order low-pass filter circuit, and the signal rectified by the rectifier circuit is input into the filter circuit for smooth filtering. Wherein, the cut-off frequency of the filter resistor and the filter capacitor in the filter circuit is determined according to the frequency of the actual square wave signal.
In this embodiment, the relay driving circuit adopts an MOSFET, and a signal filtered by the filter circuit is input to a gate of the MOSFET, that is, the square wave signal is transmitted to the rectifier circuit through the transformer, and is rectified and then is sent to the filter circuit to be smoothed to generate a gate driving voltage of the MOSFET, so that the MOSFET is turned on, and a contact of the relay is controlled to act.
The high-safety switching value driving output control circuit provided by the embodiment utilizes the principle that a transformer only transmits alternating current signals, generates square waves through an input/output (IO) port of a microprocessor, transmits energy through the transformer, and utilizes a rectifying circuit and a filter circuit to realize the driving of a relay. The control circuit provided by the embodiment can cope with the fault such as the indefinite state after the IO port fault and the microprocessor program runaway, the relay malfunction can not be caused, and the reliability and the safety of the whole instrument control system (such as a nuclear safety level DCS) are improved; and the control circuit of the invention needs few peripheral devices and is easy to realize.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A safety level switching value driving output control circuit, comprising: the device comprises a microprocessor, a transformer, a rectifying circuit, a filter circuit and a relay drive circuit; wherein the microprocessor generates a square wave signal to the transformer; the transformer transmits the square wave signal to the rectifying circuit, the rectifying circuit rectifies the square wave signal and then passes through the filter circuit, and the filtered signal is used for driving the relay driving circuit.
2. The safety level switching value driving output control circuit according to claim 1, wherein the control circuit further comprises a current limiting resistor and a protection circuit; the current-limiting resistor and the protection circuit are sequentially connected between the microprocessor and the transformer and used for protecting an I/O port of the microprocessor.
3. The safety level switching value driving output control circuit according to claim 2, wherein the protection circuit comprises a protection diode, a protection capacitor and a protection resistor; the diode is connected in series with the protective capacitor and then connected in parallel with the protective resistor; the protection circuit is connected between the common connecting end of the current-limiting resistor and the transformer and the grounding end; and the protection circuit is connected with the primary side of the transformer in parallel.
4. The safety-class switching-value driving output control circuit as claimed in claim 3, wherein the protection diode is a Schottky diode.
5. The safety level switching value driving output control circuit according to any one of claims 1 to 4, wherein the frequency and duty cycle of the square wave signal output from the I/O port of the microprocessor are set according to the frequency of the transformer.
6. The safety-stage switching-value driving output control circuit according to any one of claims 1 to 4, wherein the rectifying circuit is a half-wave rectifying circuit or a full-wave rectifying circuit for rectifying the secondary side voltage of the transformer.
7. The safety-class switching value driving output control circuit as claimed in any one of claims 1 to 4, wherein the filter circuit is an RC first-order low-pass filter circuit, and the signal rectified by the rectifier circuit is input into the filter circuit for smoothing filtering.
8. The safety-class switching-value-driven output control circuit as claimed in claim 7, wherein the value of the RC parameter in the filter circuit is determined according to the frequency of the square wave signal.
9. The safety stage switching value driving output control circuit according to any one of claims 1 to 4, wherein the relay driving circuit is a MOSFET, and the signal filtered by the filter circuit is input to a gate of the MOSFET to drive the relay to operate when the MOSFET is turned on.
10. The safety level switching value driving output control circuit according to any one of claims 1 to 4, wherein the transformer is a 1:1 transformer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921267950.5U CN209962099U (en) | 2019-08-07 | 2019-08-07 | Safety level switching value driving output control circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201921267950.5U CN209962099U (en) | 2019-08-07 | 2019-08-07 | Safety level switching value driving output control circuit |
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| CN209962099U true CN209962099U (en) | 2020-01-17 |
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| CN201921267950.5U Active CN209962099U (en) | 2019-08-07 | 2019-08-07 | Safety level switching value driving output control circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113567843A (en) * | 2021-07-20 | 2021-10-29 | 天津津航计算技术研究所 | Circuit board active path testing method based on FPGA |
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2019
- 2019-08-07 CN CN201921267950.5U patent/CN209962099U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113567843A (en) * | 2021-07-20 | 2021-10-29 | 天津津航计算技术研究所 | Circuit board active path testing method based on FPGA |
| CN113567843B (en) * | 2021-07-20 | 2023-12-12 | 天津津航计算技术研究所 | Circuit board active path testing method based on FPGA |
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Effective date of registration: 20201229 Address after: No.3, Hongda South Road, Beijing Economic and Technological Development Zone, Daxing District, Beijing Patentee after: CHINA NUCLEAR CONTROL SYSTEM ENGINEERING Co.,Ltd. Address before: 610000, No. three, 28 south section of Ring Road, Chengdu, Sichuan Patentee before: NUCLEAR POWER INSTITUTE OF CHINA |