An alternating current detection circuit, an alternating current detection system and a traffic control machine

Abstract

The present application provides an alternating current detection circuit, an alternating current detection system and a traffic control machine, and relates to the field of electronic circuit technology. The output end of the rectifier and voltage divider module in the circuit is connected to a voltage stabilizing unit, and the voltage stabilizing unit provides a voltage stabilizing signal to the detection unit based on the rectified voltage signal, so that the detection unit outputs a voltage comparison signal based on the voltage stabilizing signal, and the voltage comparison signal is used to indicate whether the rectified voltage signal is less than a preset voltage threshold; the third end of the detection unit is also connected to the first end of the signal isolation module, and the second end of the signal isolation module is used to connect to the signal detection module in the traffic control machine, and the signal detection module is used to connect to the control end of the traffic lighting module to control the power supply of the traffic lighting module. The alternating current detection circuit provided by the present application performs voltage isolation detection through the signal isolation module, has a simple structure and low cost, and the voltage stabilizing unit can provide a voltage stabilizing signal to the detection unit, so that the detection result is more accurate.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to an alternating current detection circuit, an alternating current detection system and a traffic control machine. Background Art

[0002] Traffic signal control cards are used to control the on / off of traffic lights, including motor vehicle lights (red, green, and yellow), non-motor vehicle lights, pedestrian lights, and other lights. When a traffic light is in an abnormal state, the output voltage of the traffic signal control card will be lower than the normal voltage range. Therefore, the working state of the traffic light can be determined by detecting the output voltage of the traffic signal control card.

[0003] The existing detection method usually uses a detection circuit to detect the output voltage of the traffic signal light control card. However, in the existing detection circuit, the voltage needs to be sampled through an ADC chip, and the circuit cost is high and the structure is complex. Summary of the invention

[0004] In view of the deficiencies in the above-mentioned prior art, the present application provides an AC detection circuit, an AC detection system and a traffic control machine to solve the problems existing in the prior art.

[0005] The technical solution adopted in the embodiment of the present application is as follows:

[0006] In a first aspect, an embodiment of the present application provides an alternating current detection circuit, comprising: a rectifier and voltage divider module, a voltage detection module, and a signal isolation module; wherein the voltage detection module comprises: a voltage stabilization unit and a detection unit;

[0007] The input end of the rectifier and voltage divider module is used to connect to the AC output end of the lighting control module in the traffic control machine to rectify and divide the AC signal output by the lighting control module to obtain a rectified voltage signal. The AC output end of the lighting control module is also used to connect to the power supply end of the traffic lighting module.

[0008] The output end of the rectifier and voltage divider module is connected to the voltage stabilizing unit, and the voltage stabilizing unit is also connected to the first end and the second end of the detection unit. The voltage stabilizing unit provides a voltage stabilizing signal to the detection unit based on the rectified voltage signal, so that the detection unit outputs a voltage comparison signal based on the voltage stabilizing signal, and the voltage comparison signal is used to indicate whether the rectified voltage signal is less than a preset voltage threshold;

[0009] The third end of the detection unit is also connected to the first end of the signal isolation module, the second end of the signal isolation module is used to connect to the signal detection module in the traffic control machine, and the signal detection module is used to connect to the control end of the traffic lighting module to control the power supply of the traffic lighting module.

[0010] In one embodiment, the rectification and voltage division module comprises: a rectification unit and a voltage division unit;

[0011] The input end of the rectifier unit is the first input end of the rectifier voltage divider module, which is used to connect to the first AC output end of the lighting control module; the output end of the rectifier unit is connected to one end of the voltage divider unit; the other end of the voltage divider unit is the second input end of the rectifier voltage divider module, which is used to connect to the second AC output end of the lighting control module;

[0012] The voltage dividing point of the voltage dividing unit is the output end of the rectifying voltage dividing module.

[0013] In one embodiment, the voltage stabilizing unit includes: a voltage stabilizing diode and a voltage stabilizing resistor;

[0014] The anode of the zener diode is used to connect to the second AC output end of the lighting control module, the cathode of the zener diode is connected to one end of the zener resistor, the other end of the zener resistor is connected to the output end of the rectifier and voltage divider module, and the first and second ends of the detection unit are connected in parallel to both ends of the zener resistor.

[0015] In one embodiment, the detection unit includes: a comparison circuit;

[0016] The first input end of the comparison circuit is the first end of the detection unit, the second input end of the comparison circuit is the second end of the detection unit, and the output end of the comparison circuit is the third end of the detection unit.

[0017] In one embodiment, the comparison circuit includes: a PNP transistor;

[0018] The emitter of the PNP transistor is the first input terminal of the comparison circuit, the base of the PNP transistor is the second input terminal of the comparison circuit, and the collector of the PNP transistor is the output terminal of the comparison circuit. In one embodiment, the signal isolation module includes: a photocoupler and a pull-up resistor;

[0019] The first pin of the photoelectric coupler is the first end of the signal isolation module, the second pin of the photoelectric coupler is used to connect to the second AC output end of the lighting control module, the third pin of the photoelectric coupler is grounded, the fourth pin of the photoelectric coupler is connected to the preset power supply through the pull-up resistor, and the fourth pin of the photoelectric coupler is the second end of the signal isolation module.

[0020] In one embodiment, the signal isolation module further includes: a current limiting resistor;

[0021] One end of the current limiting resistor is the first end of the signal isolation module, and the other end of the current limiting resistor is connected to the first pin of the photoelectric coupler.

[0022] In one embodiment, the second end of the signal isolation module is used to connect to the interrupt input port of the signal detection module.

[0023] In a second aspect, an embodiment of the present application provides an alternating current detection system, comprising: at least one alternating current detection circuit, wherein each of the alternating current detection circuits is an alternating current detection circuit as described in any of the above embodiments;

[0024] The input ends of the at least one AC power detection circuit are respectively used to connect to at least one set of AC output ends of the lighting control module in the traffic control machine, and the at least one set of AC output ends of the lighting control module are also respectively used to connect to the power supply end of at least one traffic lighting module, and the output ends of the at least one AC power detection circuit are respectively used to connect to at least one input end of the signal detection module in the traffic control machine.

[0025] In a third aspect, an embodiment of the present application provides a traffic control machine, comprising at least: a lighting control module, a signal detection module, and the AC detection system described in the above embodiment;

[0026] At least one group of AC output ends of the lighting control module are respectively connected to the input end of at least one AC power detection circuit in the AC power detection system, and at least one group of AC output ends of the lighting control module are also respectively used to connect to the power supply end of at least one traffic lighting module; the output ends of at least one AC power detection circuit in the AC power detection system are respectively connected to at least one input end of the signal detection module.

[0027] The beneficial effects of the present application are as follows: the present application provides an alternating current detection circuit, which includes a rectification and voltage division module, a voltage detection module, and a signal isolation module.

[0028] Among them, the voltage detection module includes a voltage stabilizing unit and a detection unit; the input end of the rectifier and voltage divider module is used to connect to the AC output end of the lighting control module in the traffic control machine to rectify and divide the AC signal output by the lighting control module to obtain a rectified voltage signal, and the AC output end of the lighting control module is also used to connect to the power supply end of the traffic lighting module; the output end of the rectifier and voltage divider module is connected to the voltage stabilizing unit, and the voltage stabilizing unit is also connected to the first end and the second end of the detection unit. The voltage stabilizing unit provides the detection unit with a voltage stabilizing signal based on the rectified voltage signal, so that the detection unit outputs a voltage comparison signal based on the voltage stabilizing signal, and the voltage comparison signal is used to indicate whether the rectified voltage signal is less than a preset voltage threshold; the third end of the detection unit is also connected to the first end of the signal isolation module, and the second end of the signal isolation module is used to connect to the signal detection module in the traffic control machine, and the signal detection module is used to connect to the control end of the traffic lighting module to control the power supply of the traffic lighting module.

[0029] Compared with the prior art that samples voltage through an ADC chip, the present application can determine whether the AC signal output by the lighting control module is less than a preset voltage threshold through a voltage detection module. It has a simple structure and low circuit cost. In addition, the voltage stabilizing unit can provide a voltage stabilizing signal to the detection unit, thereby improving the stability of the voltage and thereby improving the accuracy of the detection result. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 It is a structural schematic diagram of an existing detection circuit;

[0032] Figure 2 A schematic diagram of the structure of an alternating current detection circuit provided in an embodiment of the present application;

[0033] Figure 3 A schematic diagram of the structure of an alternating current detection circuit provided in another embodiment of the present application;

[0034] Figure 4 A schematic diagram of the structure of an alternating current detection circuit provided in yet another embodiment of the present application;

[0035] Figure 5 One of the schematic diagrams of output voltage provided by an embodiment of the present application;

[0036] Figure 6A detection schematic diagram when the output voltage provided by an embodiment of the present application is less than a preset voltage threshold;

[0037] Figure 7 A second schematic diagram of an output voltage provided by an embodiment of the present application;

[0038] Figure 8 A schematic diagram of detection when the output voltage provided by an embodiment of the present application exceeds a preset voltage threshold;

[0039] Fig. 9 A schematic diagram of the structure of an alternating current detection system provided in one embodiment of the present application;

[0040] Fig.10 A schematic diagram of the structure of a traffic control machine provided in one embodiment of the present application. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0042] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0043] In the description of the present application, it should be noted that if the terms "upper", "lower", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or is the orientation or position relationship in which the product of the application is usually placed when used. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0044] In addition, the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0045] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, it can be a direct connection, it can be an indirect connection through an intermediate medium, and it can be the internal communication of two elements. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0046] It should be noted that, in the absence of conflict, the features in the embodiments of the present application may be combined with each other.

[0047] Traffic control machine is a traffic management facility that can change the order of road traffic signals, adjust the timing and control the operation of road traffic lights. Traffic control machine is used to guide traffic and ensure traffic safety. It is the core component of the urban traffic signal control system and has functions such as traffic signal collection, communication, and intersection monitoring.

[0048] The traffic control machine is integrated with a light control card, which is used to control the 220V power output and the switch control of traffic lights, including the control of motor vehicle lights (red light, green light, yellow light), non-motor vehicle lights, pedestrian lights and other signal lights.

[0049] According to the GB14887 road signal standard, when the input voltage of the traffic light is lower than 90V, the traffic light must be turned off and stop emitting visible light. Therefore, the traffic control machine must have the function of detecting the output voltage of the light control card. The existing detection method is to Figure 1 The detection circuit shown in the figure divides the voltage after connecting the AC in series with the resistor, and determines the on / off or amplitude of the voltage by detecting the voltage on the resistor. This detection method requires sampling through an ADC chip, which has high circuit cost. At the same time, for safety performance and anti-interference, electrical isolation between the strong AC power and the weak power of the microprocessor is required, and its circuit structure is complex.

[0050] In response to the above problems, the present application provides an AC power detection circuit, which can be used to detect the output voltage of the lighting control card while solving the above problems. The following is a specific example description of the AC power detection circuit provided by the present application through multiple examples in combination with the accompanying drawings.

[0051] Figure 2 This is a schematic diagram of the structure of an AC detection circuit provided in an embodiment of the present application, referring to Figure 2 The AC power detection circuit of the present application includes a rectifier and voltage divider module 1, a voltage detection module 2, and a signal isolation module 3, wherein the voltage detection module includes a voltage stabilization unit and a detection unit.

[0052] The input end of the rectifier and voltage divider module is used to connect to the AC output end of the lighting control module in the traffic control machine to rectify and divide the AC signal output by the lighting control module to obtain a rectified voltage signal. The AC output end of the lighting control module is also used to connect to the power supply end of the traffic lighting module. Based on this connection, the lighting control module can control the traffic lighting module.

[0053] The traffic lighting module may be, for example, a traffic light, and the lighting control module may be a light control card, or any other module capable of controlling a traffic light.

[0054] The output end of the rectifier and voltage divider module is connected to the voltage stabilizing unit, which is also connected to the first and second ends of the detection unit. The voltage stabilizing unit can provide a voltage stabilizing signal to the detection unit based on the rectified voltage signal. The function of the voltage stabilizing unit is to reduce the ripple coefficient and improve the stability of the voltage. The detection unit can output a voltage comparison signal based on the voltage stabilizing signal. The voltage comparison signal is used to indicate whether the rectified voltage signal is less than a preset voltage threshold (i.e., a threshold voltage). The numerical value of the preset voltage threshold that can be detected by the circuit of the present application is determined by the rectifier and voltage divider module, specifically, it is determined by the rectifier and voltage divider module rectifying and voltage dividing the AC signal output by the lighting control module.

[0055] The third end of the detection unit is also connected to the first end of the signal isolation module, and the second end of the signal isolation module is used to connect to the signal detection module in the traffic control machine. The function of the signal isolation module is to isolate strong and weak electrical signals between the rectifier voltage divider module and the voltage detection module connected to the first end and the signal detection module connected to the second end. The signal detection module is used to connect to the control end of the traffic lighting module to control the power supply of the traffic lighting module.

[0056] Specifically, the signal detection module can be a CPU composed of a single-chip microcomputer, and the pin can be configured as an interrupt input port, that is, the second end of the signal isolation module is used to connect to the interrupt input port of the signal detection module. The interrupt signal port can determine whether the AC signal output by the lighting control module has reached a preset voltage threshold by detecting the number of pulses per unit time (for example, 50Hz).

[0057] In summary, the present application provides an AC detection circuit, which can determine whether the AC signal output by the lighting control module is less than a preset voltage threshold through a voltage detection module. It has a simple structure and low circuit cost. In addition, the voltage stabilizing unit can provide a voltage stabilizing signal to the detection unit, thereby improving the stability of the voltage and thereby improving the accuracy of the detection result.

[0058] The following combination Figure 3 and Figure 4 , the specific implementation of the AC power detection circuit of the present application is described.

[0059] like Figure 3 As shown, the rectifier and voltage divider module may include a rectifier unit and a voltage divider unit, wherein the rectifier unit may be, for example, a rectifier diode D1, which can make the voltage conduct in the positive half cycle and cut off in the negative half cycle, and reduce the power consumption of the AC detection circuit by half; the voltage divider unit may be, for example, composed of voltage divider resistors R1 and R2, R1 and R2 may be set as adjustable resistors, and by adjusting the resistance values ​​of R1 and R2, the preset voltage threshold that the AC detection circuit can detect can be controlled.

[0060] Taking the AC signal output by the lighting control module as 220V as an example, the rectifier diode D1 can realize half-wave rectification of the AC 220V, conduct in the positive half cycle of the voltage, and cut off in the negative half cycle, and reduce the power consumption of the AC detection circuit by half. The model of the rectifier diode D1 is preferably 1N4007. Resistors R1 and R2 can divide the rectified voltage. Taking the AC signal output by the lighting control module as 220V and the preset voltage threshold detected by the AC detection circuit as 90V as an example, the resistance value of R1 is set to 100KΩ and the resistance value of R2 is set to 4.7KΩ, so as to realize the detection of 90V voltage.

[0061] The input end of the rectifier unit, i.e., the anode of the rectifier diode D1, is the first input end of the rectifier voltage divider module, which is used to connect to the first AC output end of the lighting control module. The output end of the rectifier unit, i.e., the cathode of the rectifier diode D1, is used to connect to one end of the voltage divider unit (one end of the resistor R1); the other end of the voltage divider unit (one end of the resistor R2) is the second input end of the rectifier voltage divider module, which is used to connect to the second AC output end of the lighting control module; the voltage dividing point of the voltage divider unit (the connection point of R1 and R2) is the output end of the rectifier voltage divider module. Among them, the first AC output end of the lighting control module is the live wire (LiveWire), represented by L, and the second AC output end of the lighting control module is the neutral wire (Neutral Wire), represented by N.

[0062] Continue to refer to Figure 3 The voltage stabilizing unit includes a voltage stabilizing diode ZD1 and a voltage stabilizing resistor R3. The anode of the voltage stabilizing diode ZD1 is used to connect to the second AC output terminal (neutral line N) of the lighting control module, the cathode of the voltage stabilizing diode is connected to one end of the voltage stabilizing resistor R3, and the other end of the voltage stabilizing resistor R3 is connected to the output terminal of the rectifier voltage divider module, that is, the connection point of R1 and R2. The first end and the second end of the detection unit are connected in parallel to the two ends of the voltage stabilizing resistor. The voltage stabilizing diode ZD1 can be a voltage stabilizing diode with a voltage of 5.1V. The function of R3 is to provide a voltage stabilizing current for the voltage stabilizing diode, which can be selected as 4.7KΩ.

[0063] The detection unit may be, for example, a comparison circuit, wherein the first input end of the comparison circuit is the first end of the detection unit, the second input end of the comparison circuit is the second end of the detection unit, and the output end of the comparison circuit is the third end of the detection unit. The first input end of the comparison circuit is used to connect to the output end of the rectifier voltage divider module, and the second input end of the comparison circuit is used to connect to the cathode of the voltage-stabilizing diode ZD1. When the voltage at the first input end of the comparison circuit is greater than the voltage at the second input end, the circuit is turned on, and when the voltage at the first input end of the comparison circuit is less than or equal to the voltage at the second input end, the circuit is not turned on.

[0064] The function of the comparison circuit is: if the voltage value flowing out through the rectifier and voltage divider module is greater than the preset voltage threshold, the circuit is turned on; if the voltage value flowing out through the rectifier and voltage divider module is less than or equal to the preset voltage threshold, the circuit is turned off.

[0065] In one embodiment, the comparison circuit may be, for example, a PNP transistor, represented by Q1. Figure 3As shown, the emitter of the PNP transistor is the first input terminal of the comparison circuit, the base of the PNP transistor is the second input terminal of the comparison circuit, and the collector of the PNP transistor is the output terminal of the comparison circuit. The PNP transistor can be a low-power transistor similar to 2N551. The purpose of low power is to make the size of the components small enough, reduce the circuit volume when the circuit is packaged, and the circuit can be used in small usage scenarios.

[0066] In the voltage detection module, a voltage detection module is established by three devices, namely, the voltage zener diode ZD1, the voltage zener resistor R3 and the PNP transistor. When the AC signal output by the lighting control module passes through the rectifier and voltage divider module, the voltage entering the voltage detection module is less than 5.8V. At this time, the voltage of the voltage zener diode ZD1 has not been established, and the voltage between the emitter and base of the PNP transistor (Q1) is less than 0.7V. The transistor is not turned on, and there is no current on the signal isolation module. When the voltage is greater than 5.8V, the voltage between the emitter and base of the PNP transistor is clamped to 0.7V, and current flows between the emitter and base, so the transistor enters the on state, and current begins to form on the signal isolation module, and the signal isolation module begins to turn on.

[0067] In one embodiment, if Figure 4 As shown, the comparison circuit can also be composed of an operational amplifier, the non-inverting input terminal of the operational amplifier is the first input terminal of the comparison circuit, the inverting input terminal of the operational amplifier is the second input terminal of the comparison circuit, and the output terminal of the operational amplifier is the output terminal of the detection unit.

[0068] In this embodiment, the non-inverting input terminal of the operational amplifier is used to connect to the output terminal of the rectifier voltage divider module, and the inverting input terminal of the operational amplifier is used to connect to the cathode of the voltage zener diode ZD1. When the voltage of the non-inverting input terminal is greater than the inverting input terminal, the circuit is turned on, and when the voltage of the non-inverting input terminal is less than or equal to the inverting input terminal, the circuit is not turned on. However, in this case, the operational amplifier needs to be powered by a power supply, and the circuit is relatively complicated.

[0069] The signal isolation module may include a photocoupler U3 and a pull-up resistor R5, the first pin of the photocoupler is the first end of the signal isolation module, the second pin of the photocoupler is used to connect to the second AC output end (neutral line N) of the lighting control module, the third pin of the photocoupler is grounded, and the fourth pin of the photocoupler is connected to a preset power supply through a pull-up resistor R5, the preset power supply may be a power supply with an output voltage of 3.3V, and the fourth pin of the photocoupler is the second end of the signal isolation module, which is used to connect to the signal detection module in the traffic control machine.

[0070] The optocoupler can be an optocoupler with a current transfer ratio of more than 50%, such as the optocoupler of model PC817. In the present application, the optocoupler mainly functions to isolate strong and weak electrical signals. The resistance value of the pull-up resistor R5 can be set to 10KΩ, so that as long as the optocoupler has a driving current of 0.5mA, the voltage at its output end can be close to 0 when the optocoupler is turned on.

[0071] The signal isolation module may also include a current limiting resistor R4, one end of which is the first end of the signal isolation module, and the other end of which is connected to the first pin of the photoelectric coupler. The function of the current limiting resistor is to limit the current flowing into the first pin of the photoelectric coupler, thereby protecting the photoelectric coupler. When the PNP transistor is turned on, the transistor still works in an amplified state due to the small current. The driving current of the photoelectric coupler has nothing to do with the voltage drop of the light-emitting diode of the photoelectric coupler, so the resistance value of R4 does not need to be too large, and R4 can be set to an adjustable resistor with a resistance range of 100Ω to 3KΩ.

[0072] When the circuit is working, the driving current of the optocoupler in the signal isolation module = (input voltage * R2 / (R1+R2)-(Zener voltage + 0.7)) / 100KΩ-0.7V / R3-5.8 / R2; when the AC signal output by the lighting control module is less than the threshold voltage, the transistor is not turned on and the driving current = 0; when the AC signal output by the lighting control module is equal to the threshold voltage, the Zener voltage is established, the transistor is just turned on, and the driving current of the optocoupler = (threshold voltage * R2 / (R1+R2)-(Zener voltage + 0.7)) / 100KΩ-0.7V / R3-5.8 / R2, and the driving current is still = 0; when the AC signal output by the lighting control module is greater than the threshold voltage, the driving current of the optocoupler = (input voltage-threshold voltage) / 100KΩ, and the driving current of the optocoupler increases.

[0073] As described in the above embodiment, the signal detection module can be a CPU composed of a single-chip microcomputer, and the pin can be configured as an interrupt input port. The interrupt signal port can determine whether the AC signal output by the lighting control module reaches a preset voltage threshold by detecting the number of pulses per unit time (for example, 50Hz).

[0074] Specifically, when the voltage of the AC signal output by the lighting control module does not reach the preset voltage threshold (threshold voltage), the photocoupler does not pass current at this time, the output of the photocoupler is always high, and the single-chip microcomputer cannot detect the pulse input. When the AC signal output by the lighting control module is greater than the threshold voltage and reaches a certain amplitude, the photocoupler is turned on and outputs a low level. In this way, a low level will be output at each positive half-wave of the AC, and the photocoupler will always be high at the negative half-cycle of the AC. Overall, a 50HZ AC will output a pulse with a frequency of 50Hz, and a 60Hz AC will output a pulse with a frequency of 60Hz.

[0075] According to the GB14887 standard, when the input voltage of a traffic light is lower than 90V, the traffic light must stop emitting visible light. The following takes an AC detection circuit with a threshold voltage of 90V as an example to describe the entire working process of the AC detection circuit of the present application.

[0076] When the input voltage is less than 90V (see Figure 5 ), the negative half cycle of the voltage is cut off by the rectifier diode D1, and the peak voltage of the sine wave of the positive half cycle AC voltage is less than 127V (1.414*threshold voltage). After the voltage is divided by resistors R1 and R2:

[0077] Output voltage = (90*1.414-0.7)*R2 / (R1+R2) = 5.68V, which is less than 5.8V. At this time, the voltage of the voltage regulator has reached 5.1V, but the voltage between the emitter and base of the PNP transistor is less than 0.7V, so the PNP transistor is not turned on, and no current flows through the photocoupler. The output of the photocoupler is always at a high level, and the microcontroller port detection is also always at a high level (see Figure 6 ).

[0078] When the input voltage is greater than 90V (see Figure 7 ), taking the input voltage of 220V AC as an example, the negative half cycle of the voltage is still cut off by the rectifier diode D1, and the peak voltage of the sine wave of the positive half cycle AC voltage is greater than 127V (1.414*threshold voltage). After the voltage is divided by R1 and R2 resistors:

[0079] Output voltage = (220*1.414-0.7)*R2 / (R1+R2) is greater than 5.8V. At this time, the voltage of the voltage regulator ZD1 has been established at 5.1V, and the voltage between the emitter and the base of the PNP transistor gradually increases with the increase of the output voltage, until the emitter and the base of the PNP transistor are connected, and the emitter and the collector of the transistor are connected. Since the transistor amplification factor is generally greater than 50-100 times, the base current is generally very small, about tens of microamperes, and the input voltage of the transistor is constant at 5.1+0.7=5.8V. As the output voltage rises, the current passing through the photocoupler continues to increase, and the photocoupler outputs a 50Hz frequency signal. The microcontroller detects a frequency of 50Hz (see Figure 8 ).

[0080] Therefore, when the output voltage to be detected is lower than the threshold value, the optocoupler will always output a high level. When the output voltage to be detected is higher than the threshold value by a certain amplitude, the optocoupler will output a square wave with the same frequency as the AC voltage.

[0081] The present application can ensure that as long as there is a frequency pulse, the input voltage must be higher than the threshold voltage, indicating that the input voltage is normal. If it is lower than the threshold value, the output of the optocoupler must be a high level.

[0082] In summary, the present application provides an AC power detection circuit suitable for power supply detection of traffic control machines and traffic lights.

[0083] The AC power detection circuit of the present application can be used for detecting AC voltage. By adjusting the resistance parameters, a relatively accurate detection voltage threshold can be set for the AC power detection circuit of the present application. Taking the threshold voltage of 90V as an example, when the AC voltage is lower than 90V, the output will always maintain a high level, so that the signal detection module can correctly detect the fault voltage and control the traffic light to turn off. When the voltage returns to above 90V, the signal detection module detects that the voltage is normal and controls the traffic light to emit visible light.

[0084] In addition, the AC detection circuit of the present application can also be used in a light control card. The function of the light control card is to output a 220V voltage and control the on and off of the red light, yellow light, and green light. The red, yellow, and green lights are a group of signal lights. Only one of the three signal lights can be on at the same time. When the external construction is not standardized or there is a fault, multiple signal lights may be on at the same time. At this time, the output voltage of the light control card will be abnormal. If the traffic control machine is integrated with the AC detection circuit provided by the present application, it can detect the phenomenon of several signal lights being on at the same time and issue a fault alarm in time. Here, it is necessary to detect whether the output voltage of the light control card is normal. The detection voltage is also a low threshold voltage, which is generally set at around 140V.

[0085] like Fig. 9 As shown, based on the AC power detection circuit provided in the above embodiments, the present application also provides an AC power detection system, including at least one AC power detection circuit, wherein each AC power detection circuit is the AC power detection circuit described in any of the above embodiments.

[0086] The input ends of at least one AC power detection circuit are respectively used to connect to at least one set of AC output ends of the lighting control module in the traffic control machine, and the at least one set of AC output ends of the lighting control module are also respectively used to connect to the power supply end of at least one traffic lighting module. The output ends of at least one AC power detection circuit are respectively used to connect to at least one input end of the signal detection module in the traffic control machine.

[0087] The signals between the AC detection circuits are isolated and do not affect each other, thus realizing voltage detection of multiple AC voltages.

[0088] like Fig.10 As shown, the present application also provides a traffic control machine, which at least includes a lighting control module 4, an alternating current detection system 5 provided in the above embodiment, and a signal detection module 6.

[0089] At least one group of AC output ends of the lighting control module are respectively connected to the input end of at least one AC power detection circuit in the AC power detection system, and at least one group of AC output ends of the lighting control module are also respectively used to connect to the power supply end of at least one traffic lighting module; the output ends of at least one AC power detection circuit in the AC power detection system are respectively connected to at least one input end of the signal detection module.

[0090] The traffic control machine can detect the AC signal output by the lighting control module. When the AC signal output by the lighting control module is less than a preset voltage threshold (eg 90V), the traffic light is controlled to turn off and stop emitting visible light.

[0091] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An alternating current detection circuit, characterized in that: include: Rectification and voltage division module, voltage detection module, signal isolation module; wherein the voltage detection module includes: a voltage stabilization unit and a detection unit; The input end of the rectifier and voltage divider module is used to connect to the AC output end of the lighting control module in the traffic control machine to rectify and divide the AC signal output by the lighting control module to obtain a rectified voltage signal. The AC output end of the lighting control module is also used to connect to the power supply end of the traffic lighting module. The output end of the rectifier and voltage divider module is connected to the voltage stabilizing unit, and the voltage stabilizing unit is also connected to the first end and the second end of the detection unit. The voltage stabilizing unit provides a voltage stabilizing signal to the detection unit based on the rectified voltage signal, so that the detection unit outputs a voltage comparison signal based on the voltage stabilizing signal, and the voltage comparison signal is used to indicate whether the rectified voltage signal is less than a preset voltage threshold; The third end of the detection unit is also connected to the first end of the signal isolation module, the second end of the signal isolation module is used to connect to the signal detection module in the traffic control machine, and the signal detection module is used to connect to the control end of the traffic lighting module to control the power supply of the traffic lighting module; The voltage stabilizing unit includes: a voltage stabilizing diode and a voltage stabilizing resistor; The anode of the voltage-stabilizing diode is used to connect to the second AC output terminal of the lighting control module, the cathode of the voltage-stabilizing diode is connected to one end of the voltage-stabilizing resistor, the other end of the voltage-stabilizing resistor is connected to the output end of the rectifier and voltage-dividing module, and the first end and the second end of the detection unit are connected in parallel to the two ends of the voltage-stabilizing resistor; The detection unit comprises: a comparison circuit; The first input end of the comparison circuit is the first end of the detection unit, the second input end of the comparison circuit is the second end of the detection unit, and the output end of the comparison circuit is the third end of the detection unit; The comparison circuit comprises: an operational amplifier; the non-inverting input terminal of the operational amplifier is the first input terminal of the comparison circuit, the inverting input terminal of the operational amplifier is the second input terminal of the comparison circuit, and the output terminal of the operational amplifier is the output terminal of the comparison circuit.

2. The alternating current detection circuit according to claim 1, characterized in that: The rectification and voltage division module comprises: a rectification unit and a voltage division unit; The input end of the rectifier unit is the first input end of the rectifier voltage divider module, which is used to connect to the first AC output end of the lighting control module; the output end of the rectifier unit is connected to one end of the voltage divider unit; the other end of the voltage divider unit is the second input end of the rectifier voltage divider module, which is used to connect to the second AC output end of the lighting control module; The voltage dividing point of the voltage dividing unit is the output end of the rectifying and voltage dividing module.

3. The alternating current detection circuit according to claim 1, characterized in that: The comparison circuit comprises: a PNP type transistor; The emitter of the PNP transistor is the first input terminal of the comparison circuit, the base of the PNP transistor is the second input terminal of the comparison circuit, and the collector of the PNP transistor is the output terminal of the comparison circuit.

4. The AC detection circuit according to claim 1, characterized in that: The signal isolation module includes: a photoelectric coupler and a pull-up resistor; The first pin of the photoelectric coupler is the first end of the signal isolation module, the second pin of the photoelectric coupler is used to connect to the second AC output end of the lighting control module, the third pin of the photoelectric coupler is grounded, the fourth pin of the photoelectric coupler is connected to the preset power supply through the pull-up resistor, and the fourth pin of the photoelectric coupler is the second end of the signal isolation module.

5. The alternating current detection circuit according to claim 4, characterized in that: The signal isolation module also includes: a current limiting resistor; One end of the current limiting resistor is the first end of the signal isolation module, and the other end of the current limiting resistor is connected to the first pin of the photoelectric coupler.

6. The alternating current detection circuit according to claim 1, characterized in that: The second end of the signal isolation module is used to connect to the interrupt input port of the signal detection module.

7. An alternating current detection system, characterized in that: include: At least one AC power detection circuit, wherein each of the AC power detection circuits is an AC power detection circuit as described in any one of claims 1 to 6 above; The input ends of the at least one AC power detection circuit are respectively used to connect to at least one set of AC output ends of the lighting control module in the traffic control machine, and the at least one set of AC output ends of the lighting control module are also respectively used to connect to the power supply end of at least one traffic lighting module, and the output ends of the at least one AC power detection circuit are respectively used to connect to at least one input end of the signal detection module in the traffic control machine.

8. A traffic control machine, characterized in that: At least: A lighting control module, a signal detection module, and an AC power detection system as described in claim 7; At least one group of AC output ends of the lighting control module are respectively connected to the input end of at least one AC power detection circuit in the AC power detection system, and at least one group of AC output ends of the lighting control module are also respectively used to connect to the power supply end of at least one traffic lighting module; the output ends of at least one AC power detection circuit in the AC power detection system are respectively connected to at least one input end of the signal detection module.

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