CN2214049Y - Soft starter for a. c. electric motor - Google Patents

Soft starter for a. c. electric motor Download PDF

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Publication number
CN2214049Y
CN2214049Y CN 94231561 CN94231561U CN2214049Y CN 2214049 Y CN2214049 Y CN 2214049Y CN 94231561 CN94231561 CN 94231561 CN 94231561 U CN94231561 U CN 94231561U CN 2214049 Y CN2214049 Y CN 2214049Y
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China
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circuit
phase
amplifier
output
resistance
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Expired - Fee Related
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CN 94231561
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Chinese (zh)
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王子贵
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SHENYANG POLYTECHNICAL PROFESSIONAL COLLEGE
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SHENYANG POLYTECHNICAL PROFESSIONAL COLLEGE
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Abstract

The utility model relates to a soft starter for a.C. Electric motor. A three-phase alternating current is connected with a thyristor installed on a radiating fin by a protection switch. The thyristor uses a detection and control circuit on a circuitboard installed on the radiating fin to control the angle of flow. The detection and control circuit comprises the synchronous detection circuit of three-phase input voltage, a three-phase current, three-phase voltage, and a current, a power factor measuring circuit, and the drive circuit of a microcomputer control and bidirectional thyristor. After a microcomputer analyzes and calculates the data of voltage and current which are detected, the soft starter for a.C. Electric motor sends out delaying pulse. The drive circuit is used for regulating the angle of flow of the thyristor, which enables the electric motor to lie in the optimum start-up or operating state.

Description

Soft starter for a. c. electric motor
The utility model relates to Motor Control, particularly the soft initiator of alternating current motor.
Existing Electric Motor Soft-starter is mainly machinery or dynamo-electric integrated structure, comes voltage, electric current etc. to motor to make qualitative detection with detection meanss such as transformer step-down, resolution elements, by controllable silicon motor is controlled then.This soft initiator detection and control precision are relatively poor, often do not reach energy-conservation optimum efficiency, again owing to containing mechanical detection means, so the volume that seems is bigger.
The purpose of this utility model provides a kind of detection and the less alternating current motor soft initiator of control precision height, good energy-conserving effect and volume.
The utility model is achieved in that protection switch, transformer, starting resistance, axial flow blower, fin, controllable silicon and circuit board are installed in the housing; be equipped with data display board on the case lid; three-phase alternating current is connected with controllable silicon on being installed in fin through protection switch, and controllable silicon is controlled its angle of flow by detection on the circuit board that is installed on the fin and control circuit.Detection and control circuit are cores of the present utility model, and it comprises three-phase input voltage, three-phase current, three-phase voltage is synchronous and the three-phase current sync detection circuit; The power-factor measurement circuit; System controlled by computer and bidirectional triode thyristor drive circuit.Its principle is, go out corresponding numerical value input microcomputer after amplification, rectification become the signal of telecommunication to send the A/D conversion by three-phase input voltage and three-phase current detection to motor, simultaneously to three-phase voltage with electric current carries out synchronous detecting after the power-factor measurement circuit is imported microcomputer after calculating power factor, after microcomputer calculates these data according to specific program, send delay pulse, adjust the silicon controlled angle of flow by drive circuit, make electrical motors arrive optimum start-up or running status.
In detection and control circuit, three-phase input voltage testing circuit, three-phase current detection circuit, three-phase voltage and electric current sync detection circuit and power-factor measurement circuit are the exclusive designs of the utility model.The input of three-phase input voltage testing circuit is connected with the input of bidirectional triode thyristor, and three-phase alternating voltage is through resistance R 2, capacitor C 2And resistance R 3With amplifier A 1Inverting input connect divider resistance R 3With positive input resistance R 6Be connected across resistance R 2And capacitor C 2Contact and amplifier A 1Normal phase input end between, variable resistor W 1Two ends respectively with amplifier A 1Inverting input be connected with output, by amplifier A 1The alternating voltage of output is via diode D 1, D 2And capacitor C 3The rectification circuit of forming becomes d. c. voltage signal and sends into A/D conversion back input microcomputer.Three-phase current detection circuit is to detect alternating current after capacitor C by the Hall element that is connected with the bidirectional triode thyristor output 9, resistance R 15With amplifier A 4Inverting input connect resistance R 16Be connected across amplifier A 4Normal phase input end and Hall element between, variable resistor W 6Be connected across amplifier A 4Inverting input and output between, by amplifier A 4The AC current of output is via diode D 5, D 6And capacitor C 10The rectification circuit of forming becomes direct current signal and send A/D conversion back input microcomputer.In the three-phase voltage sync detection circuit, by the amplifier A in the three-phase input voltage testing circuit 1The alternating voltage of output is through resistance R 7With variable resistor W 3Send into amplifier A 2, through waveform transformation, the output zero-crossing pulse.In the three-phase current sync detection circuit, by the amplifier A of three-phase current detection circuit 4The alternating current of output is through resistance R 17With variable resistor W 8Send into amplifier A 5, through waveform transformation, the output zero-crossing pulse.In the power-factor measurement circuit, voltage zero-cross pulse by the output of three-phase voltage sync detection circuit is divided into three the tunnel after not gate 12,13 shapings, one tunnel input microcomputer 20, the NAND gate 16 of leading up to makes frequency divider 17 do zero clearing and handles, rest-set flip-flop 14 upsets of leading up to make NAND gate 15 conductings, cause frequency divider 17 to begin counting; The current over-zero pulse that lags behind voltage by the output of three-phase current sync detection circuit is divided into two-way after not gate 18,19 shapings, one tunnel input microcomputer 20, rest-set flip-flop 14 upsets of leading up to make NAND gate 15 be in cut-off state, cause frequency divider 17 to stop counting, frequency divider 17 is with the number input microcomputer of being counted 20 then.
In order to grasp three-phase output voltage simultaneously, i.e. the situation of load terminal voltage, the utility model has also designed the three-phase output voltage testing circuit, and the input of this circuit is connected with the output of bidirectional triode thyristor circuit, and three-phase output voltage is through resistance R 9, capacitor C 5And resistance R 12With amplifier A 3Inverting input connects, divider resistance R 10With positive input resistance R 13Be connected across resistance R 9And capacitor C 5Contact and amplifier A 3Normal phase input end between, variable resistor W 4Be connected across amplifier A 3Inverting input and output between, by amplifier A 3The alternating voltage of output is via diode D 3, D 4And capacitor C 6The rectification circuit of forming becomes direct current force feed A/D conversion back input microcomputer.
The utility model is compared with prior art, gathers voltage, current signal, controls thyristor operating angle through microcomputer again by testing circuit, reaches energy-conservation optimum efficiency.The control precision height of this detection, it is obvious to control energy-saving effect in real time, again owing to adopting electronic circuit to detect and control, so volume greatly reduces.
Below in conjunction with accompanying drawing the utility model is further described.
Fig. 1 is a cut-away view of the present utility model;
Fig. 2 is an outline drawing of the present utility model;
Fig. 3 is for detecting and the control circuit schematic diagram;
Fig. 4 is bidirectional triode thyristor, input voltage detection, output voltage detection, the current detecting of a wherein phase of three-phase alternating current, the circuit diagram of voltage and current synchronous detecting;
Fig. 5 is the power-factor measurement circuit diagram of a wherein phase of three-phase alternating current;
Fig. 6 is the bidirectional triode thyristor drive circuit figure of a wherein phase of three-phase alternating current;
See Fig. 1 and Fig. 2, protection switch 3, transformer 4, starting resistance 2, axial flow blower 5, fin 7, controllable silicon 8 and circuit board 6 are installed in the housing 1, and data display board 10 is housed on the case lid 9.Three-phase alternating current is connected with controllable silicon 8 on being installed in fin 7 through protection switch 3, and controllable silicon 8 is by being installed in circuit board 6 on the fin 7 through detecting and control circuit is adjusted its angle of flow.
See Fig. 3, three-phase alternating current links to each other with motor through the bidirectional triode thyristor circuit, how to adjust the angle of flow of bidirectional triode thyristor, is the key point that realizes the utility model purpose.Draw three-phase input voltage, three-phase output voltage, three-phase current detection circuit from the bidirectional triode thyristor circuit, detect signal after A/D conversion input microcomputer.Draw three-phase voltage and electric current sync detection circuit from three-phase input voltage and three-phase current detection circuit, together send into then and import microcomputer after the power-factor measurement circuit measuring goes out power factor.Microcomputer sends delay pulse after these data based designated program are carried out computing, adjusts the angle of flow of bidirectional triode thyristor by the bidirectional triode thyristor drive circuit, makes motor start or be in optimum state during operation.
See Fig. 4, the bidirectional triode thyristor circuit is by the controllable silicon G of two parallel connected in reverse phase 1And G 2Form resistance R 1And capacitor C 1Be connected in series between the input and output of bidirectional triode thyristor circuit, play the overvoltage protection effect.
The input of input voltage detection circuit is connected with the input of bidirectional triode thyristor.Alternating voltage is through the amplitude limit resistance R 2, coupling capacitance C 2And resistance R 5With amplifier A 1Inverting input connect.Divider resistance R 3With positive input resistance R 6Be connected across resistance R 2And capacitor C 2Contact and amplifier A 1Inverting input between.Resistance R 3And R 6Contact by the amplitude limit resistance R 4Be connected with zero line.Variable resistor W 1Be connected across amplifier A 1Inverting input and output between, variable resistor W 1With resistance R 5Constitute amplifier A 1Multiplication factor regulate.Amplifier A 1In be provided with zero potentiometer W 2By amplifier A 1The alternating voltage of output is via diode D 1, D 2And capacitor C 3The rectification circuit of forming becomes d. c. voltage signal and send A/D conversion back input microcomputer.In order to strengthen the stability of output signal, at the output difference parallel resistance R of this circuit 8And capacitor C 4
Output voltage detecting circuit except that input with the output of bidirectional triode thyristor circuit is connected, its element is formed, annexation is all identical with input voltage detection circuit.Output voltage is through resistance R 9, capacitor C 5And resistance R 12With amplifier A 3Inverting input connect.Resistance R 10And R 13Be connected across resistance R 9And capacitor C 5Contact and amplifier A 3Between the normal phase input end.Resistance R 10And R 13Contact pass through resistance R 11Be connected with zero line.Variable resistor W 4Be connected across amplifier A 3Inverting input and output between.Amplifier A 3In be provided with zero potentiometer W 5By amplifier A 3The alternating voltage of output is via diode D 3, D 4And capacitor C 6The rectification circuit of forming becomes direct current force feed A/D conversion back input microcomputer.This circuit output end shunt capacitance C 7With resistance R 14
Current detection circuit is to detect alternating current after capacitor C by the Hall element 11 that is connected with the bidirectional triode thyristor circuit output end 9, resistance R 15With amplifier A 4Inverting input connect.Resistance R 16Be connected across amplifier A 4Normal phase input end and Hall element 11 between.Variable resistor W 6Be connected across amplifier A 4Inverting input and output between.Amplifier A 4In be provided with zero potentiometer W 7By amplifier A 4The alternating current of output is via diode D 5, D 6And capacitor C 10The rectification circuit of forming becomes direct current signal and send A/D conversion back input microcomputer.For making stable output signal undistorted, at the output difference shunt capacitance C of this circuit 11And resistance R 18
By the amplifier A in the input voltage detection circuit 1The alternating voltage of output is through resistance R 7With variable resistor W 3Send into amplifier A 2, through waveform transformation, the output zero-crossing pulse, this is the voltage sync detection circuit.
By the amplifier A in the current detection circuit 4The alternating current of output is through resistance R 17With variable resistor W 8Send into amplifier A 4, through waveform transformation, the output zero-crossing pulse, this is a current detection circuit.
Fig. 5 is the power-factor measurement circuit diagram, and the voltage zero-cross pulse of being exported by the voltage sync detection circuit is divided into three tunnel: one tunnel input microcomputer 20 after not gate 12,13 shapings; The NAND gate 16 of leading up to makes frequency divider 17 do zero clearing and handles; Rest-set flip-flop 14 upsets of leading up to make NAND gate 15 conductings, because another input of NAND gate 15 is connected with microcomputer, when NAND gate 15 conductings, microcomputer sends continuous angular vibration signal by NAND gate 15 to frequency divider 17, causes frequency divider 17 to begin counting.The current over-zero pulse that lags behind voltage by the output of electric current sync detection circuit is divided into two-way after not gate 18,19 shapings: one tunnel input microcomputer; Rest-set flip-flop 14 upsets of leading up to make NAND gate 15 be in cut-off state, cause frequency divider 17 to stop counting, and frequency divider 17 is with the number input microcomputer of being counted 20 then, and this numerical value is current hysteresis relief angle ψ value, and COS ψ is the power of electric motor factor.
Microcomputer 20 controls are performed such: after microcomputer 20 energisings, promptly enter reset mode, computing buffering area and various computing pointer are set to corresponding state.Microcomputer 20 inquiry A/D interface circuits, calculate the numerical value of input voltage, output voltage and electric current, carry out the variable conversion with formula Q=KI, Q is a conversion value in the formula, K is a conversion coefficient, and I is through the corresponding sampling value of input voltage, output voltage and the electric current of A/D measurement, uses conversion value Q and specified rate (that is: making motor be in the setting range of optimum start-up or running status) to compare then, if conversion value Q is not in the specified rate scope, microcomputer 20 is just adjusted; Set safety value if conversion value Q surpasses, microcomputer 20 will send alarm signal.One of them I/O interface circuit of microcomputer 20 is accepted the voltage synchronizing signal, another I/O interface circuit is accepted current synchronous signal, according to the current hysteresis relief angle ψ that the power-factor measurement circuit records, microcomputer 20 will calculate whether satisfy COS ψ＜0.9, not satisfy and then will send delay pulse.So-called " delay pulse " is extended down to certain this pulse of sending for the moment the next cycle when being meant from voltage zero-cross, be the size of may command thyristor operating angle by control " time-delay " time length.
See Fig. 6, the delay pulse signal that microcomputer 20 sends is through not gate 21, NAND gate 13,14, resistance R 20, diode D 7, again through triode T 1And T 2Power amplification, diode D 8, by transformer B to bidirectional triode thyristor G 1And G 2The angle of flow control.For the driving action of accentuator, can establish by NAND gate 22,23, variable resistor W 9, resistance R 19And capacitor C 12The RC oscillator of forming links to each other with NAND gate 24.

Claims (2)

1; a kind of alternating current motor soft initiator; protection switch; transformer; starting resistance; axial flow blower; fin; controllable silicon and circuit board are installed in the housing; three-phase alternating current is connected with controllable silicon on being installed in fin through protection switch; controllable silicon is controlled its angle of flow by detection on the circuit board that is installed on the fin and control circuit; detection and control circuit comprise the three-phase input voltage testing circuit; three-phase current detection circuit; the three-phase voltage sync detection circuit; the three-phase current sync detection circuit; the power-factor measurement circuit; system controlled by computer and bidirectional triode thyristor drive circuit is characterized in that:
The input of three-phase input voltage testing circuit is connected with the input of bidirectional triode thyristor, and three-phase alternating voltage is through resistance R 2, capacitor C 2And resistance R 5With amplifier A 1Inverting input connect divider resistance R 3With positive input resistance R 6Be connected across resistance R 2And capacitor C 2Contact and amplifier A 1Normal phase input end between, variable resistor W 1Two ends respectively with amplifier A 1Inverting input be connected with output, by amplifier A 1The alternating voltage of output is via diode D 1, D 2And capacitor C 3The rectification circuit of forming becomes d. c. voltage signal and send A/D conversion back input microcomputer;
Three-phase current detection circuit is to detect alternating current after capacitor C by the Hall original paper that is connected with the bidirectional triode thyristor output 9, resistance R 15With amplifier A 4Inverting input connect resistance R 17Be connected across amplifier A 4Normal phase input end and Hall original paper (11) between, variable resistor W 6Be connected across amplifier A 4Inverting input and output between, by amplifier A 4The alternating current of output is via diode D 5, D 6And capacitor C 10The rectification circuit of forming becomes direct current signal and send A/D conversion back input microcomputer;
In the three-phase voltage sync detection circuit, by the amplifier A in the three-phase input voltage testing circuit 1The alternating voltage of output is through resistance R 7With variable resistor W 3Send into amplifier A 2, through waveform transformation, the output zero-crossing pulse;
In the three-phase current sync detection circuit, by the amplifier A of three-phase current detection circuit 4The alternating current of output is through resistance R 17With variable resistor W 8Send into amplifier A 5, through waveform transformation, the output zero-crossing pulse;
In the power-factor measurement circuit, by the voltage zero-cross pulse of three-phase voltage sync detection circuit output through not gate (12), (13) be divided into three the tunnel after the shaping, one tunnel input microcomputer (20), the NAND gate (16) of leading up to makes frequency divider (17) do zero clearing and handles, the rest-set flip-flop (14) of leading up to upset makes NAND gate (15) conducting, cause frequency divider (17) to begin counting, by the current over-zero pulse that lags behind voltage of three-phase current sync detection circuit output through NAND gate (18), (19) be divided into two-way after the shaping, one tunnel input microcomputer (20), the rest-set flip-flop (14) of leading up to upset makes NAND gate (15) be in cut-off state, cause frequency divider (17) to stop counting, frequency divider (17) is with the number input microcomputer of being counted then.
2, alternating current motor soft initiator according to claim 1, it is characterized in that: in described detection and control circuit, also have the three-phase output voltage testing circuit, the input of this circuit is connected with the output of bidirectional triode thyristor circuit, and three-phase output voltage is through resistance R 9, capacitor C 5And resistance R 12With amplifier A 3Inverting input connects, divider resistance R 10With positive input resistance R 13Be connected across resistance R 9And capacitor C 5Contact and amplifier A 3Between the normal phase input end, variable resistor W 4Be connected across amplifier A 3Between inverting input and the output, by amplifier A 3The alternating voltage of output is via diode D 3, D 4And capacitor C 6The rectification circuit of forming becomes direct current force feed A/D conversion back input microcomputer.
CN 94231561 1994-12-19 1994-12-19 Soft starter for a. c. electric motor Expired - Fee Related CN2214049Y (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN 94231561 CN2214049Y (en) 1994-12-19 1994-12-19 Soft starter for a. c. electric motor

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Application Number Priority Date Filing Date Title
CN 94231561 CN2214049Y (en) 1994-12-19 1994-12-19 Soft starter for a. c. electric motor

Publications (1)

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CN2214049Y true CN2214049Y (en) 1995-11-29

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CN 94231561 Expired - Fee Related CN2214049Y (en) 1994-12-19 1994-12-19 Soft starter for a. c. electric motor

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102291061A (en) * 2011-08-25 2011-12-21 安徽鑫龙电器股份有限公司 Braking method of soft starter
CN101404472B (en) * 2007-06-25 2013-07-10 刘群 Low/medium voltage and high voltage motor soft starter composed by three-phase commutation bridge
CN109067258A (en) * 2018-09-20 2018-12-21 山东奥卓电气科技发展有限公司 Integrated form on-line intelligence soft starting cabinet

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101404472B (en) * 2007-06-25 2013-07-10 刘群 Low/medium voltage and high voltage motor soft starter composed by three-phase commutation bridge
CN102291061A (en) * 2011-08-25 2011-12-21 安徽鑫龙电器股份有限公司 Braking method of soft starter
CN102291061B (en) * 2011-08-25 2013-10-30 安徽鑫龙电器股份有限公司 Braking method of soft starter
CN109067258A (en) * 2018-09-20 2018-12-21 山东奥卓电气科技发展有限公司 Integrated form on-line intelligence soft starting cabinet

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C19 Lapse of patent right due to non-payment of the annual fee
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