Be applicable to the voltage sampling circuit and the controller of double power supply automatic transfer switch
Technical field
The utility model relates to a kind of electric power system double power supply automatic transfer switch commonly used, is specifically related to have the switch of voltage sampling circuit, can control realization automatically to the voltage complete detection, and realizes reliable precisely conversion.
Background technology
Double power supply automatic transfer switch is the important electrical equipment of distribution system, and general automatic change over inserts the power supply commonly used and the standby power supply two-way power supply of electric power system, and can between two power supplys, change automatically, has guaranteed the continuity and the reliability of powering load.Be installed in the diverse location in the circuit according to electrical equipment, automatic change over is divided into position of source, distribution position, load situation switch.
Controller is the important component part in the automatic change over, is equivalent to the brain of automatic change over, determines function, the Performance And Reliability of this switch product.Control system and PLC type control system that existing automatic transfer switch controller comprises the relay control type be made up of relay (like voltage relay, the time relay etc.), is made up of the separate type electronics.The shortcoming of relay control type is that volume is big, cost is high, power consumption is big, function is simple; At the bottom of the integrated level of the control system that the separate type electronics is formed, power consumption is big, and function is simple, poor reliability; And the PLC type since the PLC analog quantity be input as weak signal (be generally 0~20mA, 0~5V), need add transmitter, low-response, cost are also high, the also difficult design of human-computer interaction interface is friendly.In these controllers only the control system formed of separate type electronics be used for the load situation switch of load end, and the relay control type is less with the application of PLC type control system because its simplification more.
The automatic transfer switch controller of popular use in the market is the controller of Implemented by Using Single-chip Processor and integrated circuit, and it is powerful, and programming in logic is flexible, and human-computer interaction interface is friendly, is prone to realize that communication networking becomes electrical power distribution automatization system.The power supply phase failure pick-up unit of the disclosed transfer switching equipment of the for example Chinese utility model patent CN2482094Y of the high side controller of this type; Its voltage vector and detection mode can only be carried out the phase failure and the uneven detection of severe three-phase; Can not carry out overvoltage, under-voltage detection, measuring ability is single.The disclosed switch power fail of for example Chinese utility model patent CN200944134Y observation circuit is judged three-phase imbalance, the phase failure and dead electricity through three-phase voltage vector and optocoupler, utilizes the transformer step-down; After rectifier bridge and electric capacity rectification and voltage division; The reliability of above-mentioned voltage detecting is guaranteed in the dual measure of doing voltage measurement through Chip Microcomputer A/D, but at present in the world the electric capacity precision be superior to 5% extremely rare, the capacitance temperature influence is big; And electric capacity rectifier system ripple is big; Wave form distortion behind the bridge rectifier is considerable, so the measured voltage accuracy of bridge electric capacity rectifier system is very low, cause easily overvoltage, under-voltage in advance or the conversion that lags behind.And, this prior art voltage measurement only survey single-phase and precision low excessively, can't all do accurate overvoltage, under-voltage detection to three-phase mains voltage.The controller that and for example Chinese utility model patent CN200976513Y is disclosed; To use three-phase, the step-down of subsequent use A phase voltage always through transformer; After rectifier bridge and electric capacity rectification and voltage division; Do voltage measurement through Chip Microcomputer A/D, its measuring accuracy is low, and also not comprehensive to the detection of standby voltage quality.
It is thus clear that; There are the voltage detecting function singleness in the Implemented by Using Single-chip Processor of using at present and the automatic transfer switch controller of integrated circuit; Low to the supply voltage accuracy of detection; Twin-power switch is not often misrouted and changed, be easy to cause overvoltage, the under-voltage defective that shifts to an earlier date or lag behind conversion power supply problems such as each all does complete detection mutually with backup power source voltage, and temperature influence is big commonly used.
The utility model content
The purpose of the utility model is to overcome the above-mentioned defective of prior art; A kind of voltage sampling circuit that is applicable to double power supply automatic transfer switch is provided; Its controller is through adopting the economic high little voltage sampling circuit of temperature influence of anti-interference strong accuracy of detection; Realization is judged the complete detection and the conversion of the decompression of three-phase commonly used, subsequent use three-phase voltage, under-voltage, overvoltage and three-phase imbalance, has been guaranteed the accurate transformation of automatic change over.
To achieve these goals, the utility model provides a kind of voltage sampling circuit that is applicable to double power supply automatic transfer switch, comprises that surge suppresses and voltage detecting circuit 14, isolating amplifier circuit 15, level translation and signal amplification circuit 16; Said surge suppresses to be connected with voltage detecting circuit 14 input ends the phase line and the neutral line of sampled voltage; Output terminal connects isolating amplifier circuit 15, is used to curb the undesired signal that is coupled to the sampled voltage port and the AC power frequency signal is become the first current signal I1 export; Said isolating amplifier circuit 15 output terminals connect level translation and signal amplification circuit 16; First current signal I1 isolation is zoomed into second current signal I2 output, be used to improve the antijamming capability of sample circuit; The second current signal I2 is become d. c. voltage signal U1 for said level translation and signal amplification circuit 16 and amplification is output as the sampled voltage signal U2 that microprocessor can receive.
Further, described surge inhibition and voltage detecting circuit 14 comprise voltage dependent resistor (VDR) RV1 and current-limiting resistance R1; Current-limiting resistance R1 one end connects the phase line of sampled voltage, and an end connects the first input end of said isolating amplifier circuit 15; Voltage dependent resistor (VDR) RV1 is connected in parallel between the phase line and the neutral line of sampled voltage; The neutral line of sampled voltage connects second input end of said isolating amplifier circuit 15.
Further, described isolating amplifier circuit 15 comprises current transformer TV1; Current transformer TV1 primary side two ends connect the first input end and second input end of isolating amplifier circuit 15 respectively, and current transformer TV1 secondary side two ends connect the first input end and second input end of described level translation and signal amplification circuit 16 respectively.
Further, described level translation and signal amplification circuit 16 comprise level conversion resistance R 2, the 3rd resistance R 3, the 4th resistance R 4, filter capacitor C1, operational amplifier D1A, reference source D2; The 3rd resistance R 3 one ends connect the first input end of level translation and signal amplification circuit 16, the reverse input end of other end concatenation operation amplifier D1A; The positive input of operational amplifier D1A is connected with second input end of level translation and signal amplification circuit 16, the output terminal output sampled voltage signal U2 of operational amplifier D1A; Reference source D2 one end connects second input end of level translation and signal amplification circuit 16, other end ground connection; Level translation resistance R 2 is connected in parallel between level translation and signal amplification circuit 16 first input ends and second input end; The 4th resistance R 4 is connected in parallel between the reverse input end and output terminal of operational amplifier D1A, and filter capacitor C1 is connected in parallel between the reverse input end and output terminal of operational amplifier D1A.
Further, described current transformer TV1 employing current ratio is 1: 1 a current transformer.
Further, the resistance of described the 3rd resistance R 3 is more than 100 times of described level translation resistance R 2 resistances.
Further, described the 3rd resistance R 3, the 4th resistance R 4 are selected the resistance that the temperature drift direction is identical, temperature drift coefficient is nearer for use.
Further, described current-limiting resistance R1, level conversion resistance R 2 select for use the temperature drift direction identical, the resistance that temperature drift coefficient is nearer.
Further, the scope of the described first current signal I1 is 0 to 3mA; The scope of described d. c. voltage signal U1 is-1.5V is to 1.5V; The scope of described sampled voltage signal U2 is 0-3V.
To achieve these goals, the utility model also provides a kind of controller that has adopted the voltage sampling circuit that is applicable to double power supply automatic transfer switch, comprises that microprocessor 17, supply voltage commonly used detect loop 13, backup power source voltage detects loop 19.Wherein said supply voltage commonly used detects loop 13 and comprises three groups of voltage sampling circuits that structure is identical, converts supply voltage commonly used into sampled voltage signal U2 that three groups of microprocessors can receive; Backup power source voltage detect loop 19 comprise three groups of three groups of structures identical voltage sampling circuit, convert backup power source voltage into sampled voltage signal U2 that three groups of microprocessors can receive; The voltage sampling circuit that supply voltage commonly used detects in the loop 13 is identical with the voltage sampling circuit structure that backup power source voltage detects in the loop 19; Three groups of voltage sampling circuit input ends that supply voltage commonly used detects loop 13 connect three-phase supply A phase line NUa commonly used and neutral line NUn, three-phase supply B phase line NUb commonly used and neutral line NUn, three-phase supply C phase line NUc commonly used and neutral line NUn respectively, and output terminal connects three input end AINA0, AINA1, the AINA2 of microprocessor 17 respectively; The input end that backup power source voltage detects three groups of voltage sampling circuits in loop 19 connects subsequent use three-phase supply A phase line RUa and neutral line RUn, subsequent use three-phase supply B phase line RUb and neutral line RUn, subsequent use three-phase supply C phase line RUc and neutral line RUn respectively, and output terminal connects other three input end AINA3, AINA4, the AINA5 of microprocessor 17 respectively; Described microprocessor 17 calculates voltage effective value according to the sampled voltage signal U2 of input; Through comparing with the under-voltage value of setting, overpressure value; Detect supply voltage whether decompression, under-voltage, superpotential and or three-phase mains voltage commonly used three-phase imbalance, subsequent use three-phase mains voltage three-phase imbalance whether whether.
This voltage sampling circuit scheme that voltage sampling circuit in the described double power supply automatic transfer switch controller adopts the utility model to provide.Be that voltage sampling circuit in the described double power supply automatic transfer switch controller comprises that surge suppresses and voltage detecting circuit 14, isolating amplifier circuit 15, level translation and signal amplification circuit 16; Said surge suppresses to be connected with voltage detecting circuit 14 input ends the phase line and the neutral line of sampled voltage; Output terminal connects isolating amplifier circuit 15, is used to curb the undesired signal that is coupled to the sampled voltage port and the AC power frequency signal is become the first current signal I1 export; Said isolating amplifier circuit 15 output terminals connect level translation and signal amplification circuit 16; First current signal I1 isolation is zoomed into second current signal I2 output, be used to improve the antijamming capability of sample circuit; The second current signal I2 is become d. c. voltage signal U1 for said level translation and signal amplification circuit 16 and amplification is output as the sampled voltage signal U2 that microprocessor can receive.
Because automatic change over generally is used for the forceful electric power magnetic environment; So be positioned at that wherein controller is very easy to be interfered and moment afunction or damage; And the employing of the utility model be applicable to double power supply automatic transfer switch the controller of voltage sampling circuit through measures such as isolation, filtering, surge inhibition; Improved the comprehensive and reliability of controller voltage detecting, realized comprehensively accurately detecting of the decompression to supply voltage, under-voltage, overvoltage, three-phase imbalance, reduced the influence of temperature and mains frequency variation voltage detecting; The controller that has overcome existing automatic change over is to the voltage detecting function singleness, the shortcoming of low precision
Description of drawings
Fig. 1 is the functional block diagram of the double power supply automatic transfer switch controller of the utility model;
Fig. 2 is the circuit diagram of an embodiment of the voltage sampling circuit that is applicable to double power supply automatic transfer switch of the utility model;
Fig. 3 is the test waveform figure of Fig. 2 voltage sampling circuit.
Embodiment
Below in conjunction with the embodiment shown in the accompanying drawing 1 to 3, further describe the voltage sampling circuit that is applicable to double power supply automatic transfer switch of the utility model and adopted the double power supply automatic transfer switch controller of this voltage sampling circuit.
Fig. 1 is the functional block diagram of the double power supply automatic transfer switch controller of the utility model.Double power supply automatic transfer switch can be changed between the power supply commonly used that inserts and these two power supplys of standby power supply automatically, and power supply commonly used and standby power supply are from exchanging 50HZ, rated operational voltage to 400V and following electric power system.As shown in Figure 1; The double power supply automatic transfer switch controller comprises and uses the supply voltage detection commonly used loop 13 that power supply is connected always; The backup power source voltage that is connected with standby power supply detects loop 19 and microprocessor 17, and supply voltage commonly used detects loop 13 and is connected with microprocessor 17 respectively with the output terminal that backup power source voltage detects loop 19.Supply voltage commonly used detects loop 13 and is used to detect supply voltage commonly used, will become microprocessor 17 acceptable 0-3V (peak value) signals from the three-phase common voltage of power supply commonly used; Backup power source voltage detects loop 19 and is used to detect backup power source voltage, and the three-phase standby voltage of providing for oneself with power supply in the future becomes microprocessor 17 acceptable 0-3V (peak value) signals.Microprocessor 17 can adopt the conventional cpu chip or the microprocessor that include 12 A/D of at least 6 passages; It is the data acquisition process and the control center of double power supply automatic transfer switch controller; The effective value that be used for to use always that supply voltage detects that loop 13, backup power source voltage detect that the voltage that detects in loop 19 is discrete, filtering, scale transformation, frequency measurement calculates three-phase voltage commonly used, subsequent use three-phase voltage; Through comparing with the under-voltage value of setting, overpressure value; Judge common voltage whether decompression, under-voltage, superpotential; With three-phase mains voltage commonly used three-phase imbalance, subsequent use three-phase mains voltage three-phase imbalance whether whether, thereby detect when realizing the high-precision real to supply voltage commonly used, backup power source voltage and judge.
As shown in Figure 1, supply voltage commonly used detects loop 13 and comprises three groups of voltage sampling circuits, and backup power source voltage detects loop 19 and also comprises three groups of voltage sampling circuits, and the structure of these 6 groups of voltage sampling circuits is identical.The input that three groups of voltage sampling circuits in supply voltage detection commonly used loop 13 are every group connects three-phase supply A phase line NUa commonly used and neutral line NUn, three-phase supply B phase line NUb commonly used and neutral line NUn, three-phase supply C phase line NUc commonly used and neutral line NUn respectively, and the output terminal in supply voltage detection commonly used loop 13 connects three input end AINA0, AINA1, the AINA2 of microprocessor 17 respectively.In like manner; The input end that three groups of voltage sampling circuits in backup power source voltage detection loop 19 are every group connects subsequent use three-phase supply A phase line RUa and neutral line RUn, subsequent use three-phase supply B phase line RUb and neutral line RUn, subsequent use three-phase supply C phase line RUc and neutral line RUn respectively, and the output terminal in backup power source voltage detection loop 19 connects other three input end AINA3, AINA4, the AINA5 of microprocessor 17 respectively.
As shown in Figure 1, detecting loop 13 with supply voltage commonly used is example, and voltage sampling circuit comprises 3 parts that are connected in series successively, and promptly surge suppresses and voltage detecting circuit 14, isolating amplifier circuit 15, level translation and signal amplification circuit 16.Wherein surge suppresses to be connected with the input end of voltage detecting circuit 14 phase line (like NUa) and the neutral line (like NUn) of sampled voltage, and the output terminal of this circuit connects the input end of isolating amplifier circuit 15; The output terminal of isolating amplifier circuit 15 connects the input end of level translation and signal amplification circuit 16, and the output terminal of level translation and signal amplification circuit 16 is connected with the input end of microprocessor 17.Surge inhibition and voltage detecting circuit 14 are used to suppress to be coupled to the high pressure undesired signal of voltage port; And the AC power frequency signal is become little current signal through resistance; In the present embodiment, when supply voltage commonly used was input as the 220V ratings, little current signal optimum was 2mA ± 10%.Isolating amplifier circuit 15 is used for the isolation in 1: 1 of little current signal is zoomed into little current signal, makes supply voltage commonly used detect loop 13 and isolates the antijamming capability of raising microprocessor 17 with microprocessor 17.Level translation and signal amplification circuit 16 are used for becoming d. c. voltage signal and amplifying and raise into 0-3V (peak value) signal exchanging little current signal, supply microprocessor 17 samplings to keep calculating voltage effective value.
Be the voltage sampling circuit of example explanation the utility model mutually with power supply A commonly used according to Fig. 2 below.Because detect supply voltage commonly used loop 13 and backup power source voltage detect voltage sampling circuit in the loop 19 and realize that principle and structure are all identical, below be that example is explained its embodiment with the voltage sampling circuit figure of power supply A phase commonly used.Voltage sampling circuit as shown in Figure 2 comprises that the surge that connects successively suppresses and voltage detecting circuit 14, isolating amplifier circuit 15, level translation and signal amplification circuit 16 and microprocessor 17, and the annexation between these circuit as previously mentioned.The input signal of the voltage sampling circuit of power supply A phase commonly used is taken from power supply A phase line NUa commonly used and power supply neutral line NUn commonly used.
Surge shown in Fig. 2 left side suppresses and voltage detecting circuit 14 comprises voltage dependent resistor (VDR) RV1 and current-limiting resistance R1, and the isolating amplifier circuit 15 shown in Fig. 2 centre comprises current transformer TV1.Power supply A phase line NUa commonly used is connected with an end of current transformer TV1 primary side through current-limiting resistance R1; The other end of current transformer TV1 primary side is connected with the neutral line NUn of power supply 12 commonly used; Voltage dependent resistor (VDR) RV1 is parallelly connected with current-limiting resistance R1 summation current transformer TV1; The end of voltage dependent resistor (VDR) RV1 is connected with power supply A phase line NUa commonly used, the other end be connected with power supply neutral line NUn.Current transformer TV1 employing current ratio is 1: 1 a current transformer, the current transformer of preferred high accuracy.Current-limiting resistance R1 will use power supply A phase voltage signal Vin always, and (the little current signal I1 that Vin sensing range 0~264VAC) is transformed into 0~about 2.4mA exports to isolating amplifier circuit 15.When the voltage signal amplitude was 264VAC, little current signal amplitude was about 2.4mA ± 5%.Voltage dependent resistor (VDR) RV1 suppresses to be coupled to the high pressure undesired signal of voltage port; When thunderbolt waits surge to disturb if supply voltage commonly used has been coupled; Voltage dependent resistor (VDR) RV1 can in time disturb clamped absorption with surge, can prevent that surge from hindering and damaging the double power supply automatic transfer switch controller.The current transformer TV1 of isolating amplifier circuit 15 zooms into little current signal I2 with little current signal I1 with isolation in 1: 1; Export to level translation and signal amplifying return circuit 16; Voltage detection circuit 13 commonly used and microprocessor 17 are isolated, improve the antijamming capability of microprocessor system.
Level translation shown in Fig. 2 right side and signal amplifying return circuit 16 comprise level conversion resistance R 2, resistance R 3, resistance R 4, filter capacitor C1, operational amplifier D1A and reference source D2.One end of current transformer TV1 secondary side is connected through the reverse input end of resistance R 3 with operational amplifier D1A; The other end of current transformer TV1 secondary side is connected with the positive input of operational amplifier D1A; And the other end of current transformer TV1 secondary side is connected with reference source D2 one end, reference source D2 other end ground connection (GND).Level translation resistance R 2 is connected in the two ends of current transformer TV1 secondary side in parallel; Resistance R 4 is connected in reverse input end and the output terminal of operational amplifier D1A in parallel; Filter capacitor C1 is connected in reverse input end and the output terminal of operational amplifier D1A in parallel, and the output terminal of operational amplifier D1A is connected with the A/D input end AINA0 of microprocessor 17.Level translation resistance R 2 seals in current transformer TV1 secondary side, with the little current signal of current transformer TV1 output become small voltage signal U1 (| U1|<REF), present embodiment REF=1.25V.Carry the limitation that A/D can only import direct current signal to general single-chip microcomputer; Present embodiment adopts reference source D2 to be connected with level translation resistance R 2; U1 raises into direct current signal with AC signal; Via resistance R 3, resistance R 4,1: 1 amplifying circuit that filter capacitor C1 and operational amplifier D1A form zooms into U2, exports to microprocessor 17 again.
In the present embodiment; (0~264VAC) becomes little current signal I1 (0~about 2.4mA) through current-limiting resistance R1 to power supply A phase voltage signal Vin commonly used; When voltage signal Vin amplitude is 264VAC; Little current signal I1 amplitude is about 2.4mA ± 5%, flows into level translation resistance R 2 (330 ohm of representative values), resistance R 3 (representative value 100k ohm) through 1: 1 current transformer TV1 isolation transmit to secondary side.In the present embodiment; Because resistance R 3 resistances>>resistance of level translation resistance R 2; Think that current transformer TV1 secondary survey electric current all flows into level translation resistance R 2 so can be similar to; The scope that forms voltage U 1-1.2V~+ 1.2V between, voltage U 1 is raised through high precision reference voltage REF (representative value 1.25V), 1: 1 amplifying circuit forming via resistance R 3, resistance R 4, filter capacitor C1 and operational amplifier D1A zooms into U2; Send at least with the microprocessor 17 of 6 passage A/D, the U2 scope is 0~2.5V.Microprocessor 17 can calculate the common voltage value through filtering through discrete alternating current sampling method, through with the under-voltage value of setting, overpressure value relatively, detect common voltage whether decompression, under-voltage, superpotential, thereby realize high Precision Detection supply voltage.
Through the test proof, the thermal adaptability of present embodiment circuit is strong, need not to select the resistance of low temperature drift just can effectively reduce the precision drift that temperature variation causes.When temperature raises; That the resistance of current-limiting resistance R1 becomes is big ↑->little current signal I1 diminishes ↓->little current signal I2 diminishes ↓; But simultaneously level translation resistance R 2 resistances become big ↑; Thereby little to the ratios affect of I2*R2 and I1*R1 when temperature variation, promptly during temperature variation, voltage NUa and U1 ratio are constant basically.And the amplifying circuit of being made up of resistance R 3, resistance R 4, filter capacitor C1, operational amplifier D1A is also less to Influence of Temperature.Identical through preferred temperature drift direction and temperature drift coefficient is nearer resistance R 1 and R2, R3 and R4, then the low drift effect of the temperature of the voltage detecting precision of voltage sampling circuit is better.
Through the test proof, the present embodiment circuit is strong to the change of frequency adaptability of electrical network.The amplifying circuit filter capacitor C1 capacitive reactance of being made up of resistance R 3, resistance R 4, filter capacitor C1, operational amplifier D1A among Fig. 2 is bigger; Less to the influence of amplifying circuit precision; The remainder components and parts comprise that resistance, current transformer TV1, operational amplifier D1A are less to the variable effect of frequency, so voltage sampling circuit is strong to the adaptability of frequency among Fig. 2 embodiment.It can reach 0.5% to the measuring accuracy of 45-65Hz power supply voltage signal through test.
Fig. 3 is the test waveform figure of Fig. 2 voltage sampling circuit, comprises that waveform and its controller of the voltage NUa check point of the utility model voltage sampling circuit deliver to the waveform of the A/D input end AINA0 of microprocessor 17 through transformation isolation, hardware filtering, amplification.Can find out that from Fig. 3 measured waveform the waveform of the A/D input end AINA0 of the waveform of voltage NUa check point and microprocessor 17 is identical, does not produce distortion phenomenon.According to 500 of the double power supply automatic transfer switch controller trial targets of the above-mentioned voltage sampling circuit embodiment realization of the utility model, measuring accuracy all is lower than 0.5% through test under normal temperature condition.And take a sample test 4 at high temperature 70 degree, measuring accuracy also all is lower than 0.5%.Equally, take a sample test 4 at low temperature-25 degree, measuring accuracy all is lower than 0.5%.And this voltage sampling circuit controller trial target band twin-power switch done mechanical endurance test, and conversion and control 30000 times, the controller of test does not have any fault.Obviously, this The performance test results of the utility model far surpasses 6000 times requirement of concerned countries standard GB/T 14048.2 defineds.
The embodiment of Fig. 2 is preferred scheme of the utility model.But say from principle; Inspiration through the utility model; Design the operational amplifier that a kind of positive-negative power offers the voltage detecting loop; Each passage realizes offering after voltage detecting, lifting, the amplification method of microprocessor acquisition process also can realizing the accurate detection of quality of voltage that only the sort controller design cost is higher relatively through the double high-precision operational amplifier.In addition; What more than describe only is the preferred embodiment of the utility model; So that those skilled in the art can realize or use the disclosed content of the utility model, to those skilled in the art, all be conspicuous to the various modifications of these disclosures.The technical scheme of this area resulting any modification within the spirit of the utility model and scope, conversion, replacement all falls within the protection domain of the utility model, the double power supply automatic transfer switch that for example according to the utility model power supply commonly used or standby power supply is carried out three-phase, two phases, single-phase accurate detection; The utility model is used for motor protector, relay, instrument the detection of the decompression of three-phase mains voltage, under-voltage, overvoltage, three-phase imbalance is belonged to the protection domain of the utility model.