CN202488384U

CN202488384U - Control circuit for soft starter of motor

Info

Publication number: CN202488384U
Application number: CN201220070386XU
Authority: CN
Inventors: 季春华; 焦志刚; 徐晓阳
Original assignee: Changshu Switchgear Manufacturing Co Ltd
Current assignee: Changshu Switchgear Manufacturing Co Ltd
Priority date: 2012-02-29
Filing date: 2012-02-29
Publication date: 2012-10-10
Anticipated expiration: 2022-02-28

Abstract

The utility model relates to a control circuit, and especially relates to a control circuit for a soft starter of a motor. The control circuit comprises a microprocessor, a three-phase voltage zero-crossing sampling circuit, a thyristor conducting detection circuit, a thyristor triggering circuit, a three-phase current sampling circuit, an analog current output circuit, a signal input circuit, a signal output circuit, a communication circuit, a keyboard, an LCD (liquid crystal display), a radiator temperature detection circuit, a clock circuit, a memory, a PTC (positive temperature coefficient) protection circuit and a reset circuit. The control circuit is rich in adjustable parameter and direct in display, and can record the types of faults and the occurrence time of faults.

Description

A kind of control circuit of Electric Motor Soft-starter

Technical field

The utility model relates to a kind of control circuit, especially a kind of control circuit of Electric Motor Soft-starter.

Background technology

AC asynchronous motor is widely used in various Industry Control occasions.Traditional electric motor starting adopts the across-the-line starting mode, but starting harm is very big, can cause the decline of line voltage like excessive starting current; Influence the normal operation of miscellaneous equipment; And excessive starting current can cause very great machinery impact, and fragile equipment, this start mode seldom adopt.The substitute is the starting of Y/ Δ, from reduced voltage starting modes such as lotus root reduced voltage startings, but still the harm that exists secondary current to impact.

At present popular is to adopt soft starter to come actuating motor, because it adopts thyristor as executive component, in conjunction with the microprocessor control technology, has realized the smooth-going output of voltage, has overcome the defective of traditional start mode.Present known soft starter defencive function is perfect inadequately; As there are not required defencive functions of motor such as overload, the phase failure, stall, ground connection; There are not communication, I/O function able to programme yet; The more required function of users such as inquiry constantly takes place in fault-free record and fault, causes the objective demand that can't satisfy the user.

Summary of the invention

The utility model technical problem to be solved is the deficiency to the above-mentioned background technology, and a kind of control circuit of Electric Motor Soft-starter is provided.

The utility model adopts following technical scheme for realizing the foregoing invention purpose:

A kind of control circuit of Electric Motor Soft-starter comprises: microprocessor, three-phase voltage zero passage sample circuit, thyristor conduction detection circuit, thyristor gating circuit, three-phase current sample circuit, analog current output circuit, signal input circuit, signal output apparatus, telecommunication circuit, keyboard and LCD LCD, radiator temperature testing circuit, clock circuit, memory, PTC protective circuit, reset circuit;

Wherein, three-phase voltage zero passage sample circuit, thyristor conduction detection circuit, thyristor gating circuit, three-phase current sample circuit, analog current output circuit, signal input circuit, signal output apparatus, telecommunication circuit, keyboard are connected with microprocessor respectively with LCD LCD, radiator temperature testing circuit, clock circuit, memory, PTC protective circuit, reset circuit.

In the control circuit of said Electric Motor Soft-starter, thyristor conduction detection circuit comprises first to fourth resistance, first electric capacity, first bridge heap, the first isolation optocoupler;

Wherein, The anode of thyristor to be detected is connected with an end of first resistance; One utmost point of the other end of first resistance, first electric capacity is connected with first ac voltage input of first bridge heap respectively; The negative electrode of another utmost point of first electric capacity, thyristor to be detected is connected with second ac voltage input of first bridge heap respectively, and the positive input terminal that the positive polarity dc voltage output end of first bridge heap and first is isolated optocoupler is connected, and the negative input end that the negative polarity dc voltage output end of first bridge heap and first is isolated optocoupler is connected; The two ends of second resistance are connected with power end, the voltage source of the first isolation optocoupler respectively; The two ends of the 3rd resistance are connected with output reference end, the earth of the first isolation optocoupler respectively, and the two ends of the 4th resistance are connected with the output that voltage source, first is isolated optocoupler respectively, and first isolates the earth terminal ground connection of optocoupler.

In the control circuit of said Electric Motor Soft-starter, signal input circuit comprises: the 5th resistance, the 6th resistance, first piezo-resistance, second electric capacity, first optocoupler, first interface;

Wherein, One end of the 5th resistance is connected with voltage source; The I/O interface of the other end of the 5th resistance, microprocessor is connected with the collector electrode of first optocoupler respectively; The grounded emitter of first optocoupler, the anode of first optocoupler is connected with an end of the 6th resistance, and a utmost point of the other end of the 6th resistance, second electric capacity, an end of first piezo-resistance are connected with No. 2 pins of first interface respectively; The other end of another utmost point of second electric capacity, the negative electrode of first optocoupler, first piezo-resistance is connected with the earth respectively, and No. 1 pin of first interface connects direct voltage source.

In the control circuit of said Electric Motor Soft-starter, signal output apparatus comprises: the 7th resistance, second optocoupler, first triode, first diode, first relay;

Wherein, The two ends of the 7th resistance are connected with the anode of voltage source, second optocoupler respectively, and the negative electrode of second optocoupler is connected with the I/O interface of microprocessor, and the collector electrode of second optocoupler is connected with the base stage of first triode; The collector electrode of the emitter of second optocoupler, first triode is ground connection all; The two ends of first relay are connected with the two poles of the earth of first diode respectively, and the anode of first diode is connected with the emitter of first triode, and the negative electrode of first diode connects direct voltage source.

In the control circuit of said Electric Motor Soft-starter, telecommunication circuit comprises: the 8th to the 17 resistance, MAX1480, the 3rd electric capacity, the 4th electric capacity, first inverter, second inverter, the 3rd inverter;

Wherein, The two ends of the 8th resistance are connected with external communication interface A, B respectively; The two ends of the 9th resistance are connected with RO DRV end, the LED end of MAX1480 respectively; The two ends of the tenth resistance are connected with B end, the COM2 end of MAX1480 respectively; The two ends of the 11 resistance are connected with A end, the IVCC2 end of MAX1480 respectively; The two ends of the 12 resistance are connected with DIIN end, the IVCC2 end of MAX1480 respectively, and the two ends of the 13 resistance are connected with DEIN end, the IVCC2 end of MAX1480 respectively, and the two ends of the 14 resistance are connected with the DI end of MAX1480, the output of first reverser respectively; The two ends of the 15 resistance are connected with the DE end of MAX1480, the output of second inverter respectively; The two ends of the 16 resistance are connected with the COM2 end of external communication interface SH, MAX1480 respectively, and

end of an end of the 17 resistance, MAX1480 is connected with the first input end of the 3rd inverter respectively, and second input of the other end of the 17 resistance, the 3rd inverter is connected with voltage source respectively; The positive pole of the 3rd electric capacity is connected with the VCC2 of MAX1480 end; The minus earth of the 3rd electric capacity, the two poles of the earth of the 4th electric capacity respectively with the VCC5 of MAX1480 end, be connected, the A of MAX1480, B end are connected with external communication interface A, B respectively; The DIIN end of MAX1480 is connected with the DIDRV end; The DEIN end of MAX1480 is connected with the DEDRV end, and the IVCC1 end of MAX1480 is connected with the IVCC2 end, and the COM1 end of MAX1480 is connected with the COM2 end; The VCC1 end of MAX1480, VCC2 end, VCC3 end, VCC4 end, VCC5 end are connected respectively with voltage source, the SD end of MAX1480, earth terminal ground connection.

In the control circuit of said Electric Motor Soft-starter, clock circuit comprises: the 18 resistance, battery, crystal oscillator, DS1305;

Wherein, the VCC2 of DS1305 holds ground connection, and the VBAT end of DS1305 is connected with the positive pole of battery; GND ground connection; The X1 end of DS1305, X2 end end are connected with the two poles of the earth of crystal oscillator respectively, the GND end ground connection of DS1305, and the ERMODE end of DS1305, VCCIF end, VCC1 end are connected with voltage source; The two ends of the 18 resistance are connected with the INT0 end of voltage source, DS1305 respectively, and the SDO end of DS1305, SDI end, SCLK end connect SI, SO, SCK signal respectively.

In the control circuit of the soft initiator of said motor, the PTC protective circuit comprises: amplifier, PTC resistance;

Wherein, One utmost point of the 5th electric capacity is connected with an end of the 19 resistance; Another utmost point ground connection of the 5th electric capacity; The other end of the 19 resistance is connected with an end of the 20 resistance, an end of the 21 resistance, the output of amplifier respectively; The other end ground connection of the 20 resistance, the other end of the 21 resistance is connected with the negative input end of amplifier, and the positive input terminal of amplifier is connected with a utmost point of the 6th electric capacity, an end of the 22 resistance; Another utmost point ground connection of the 6th electric capacity; The other end of the 22 resistance is connected with a utmost point of an end of the 23 resistance, the 7th electric capacity, and the other end of the 23 resistance is connected with the negative electrode of an end of the 24 resistance, second diode, an end of the 25 resistance, and an end of the 26 resistance is connected with a utmost point of the other end of the 25 resistance, the 8th electric capacity, an end of PTC resistance; The other end of another utmost point of the other end of PTC resistance, the 8th electric capacity, the anode of second diode, the 24 resistance, another utmost point ground connection of the 7th electric capacity, the other end of the 26 resistance is connected with voltage source.

The utility model adopts technique scheme, has following beneficial effect: adjustable parameter is abundant, intuitive display, can the record trouble type and fault take place constantly.

Description of drawings

Fig. 1 is the sketch map of Electric Motor Soft-starter control circuit.

Fig. 2 is the sketch map of thyristor conduction detection circuit in the Electric Motor Soft-starter control circuit.

Fig. 3 is the sketch map of signal input circuit in the Electric Motor Soft-starter control circuit.

Fig. 4 is the sketch map of signal output apparatus in the Electric Motor Soft-starter control circuit.

Fig. 5 is the sketch map of telecommunication circuit in the Electric Motor Soft-starter control circuit.

Fig. 6 is the sketch map of clock circuit in the Electric Motor Soft-starter control circuit.

Fig. 7 is the sketch map of PTC protective circuit in the Electric Motor Soft-starter control circuit.

Fig. 8 is a power circuit.

Fig. 9 is the voltage zero-cross sample circuit.

Figure 10 is a thyristor gating circuit.

Figure 11 is a current sampling circuit.

Figure 12 is a 4-20mA analog current output circuit.

Figure 13 is the radiator temperature testing circuit.

Figure 14 is a memory circuit.

Figure 15 is a reset circuit.

Label declaration: R1 to R26 is the first to the 26 resistance among the figure, and C1 to C8 is first to the 8th electric capacity, and B1 to B6 is first to the 6th bridge heap; BR1 to BR4 is first to fourth isolation optocoupler, and O1, O2, O3 are respectively first, second, third optocoupler, and RV1 is first piezo-resistance; J1, J2 are first, second interface, and RL1 is first relay, and D1, D2 are respectively first, second diode; Q1 is first triode, and U1, U2, U3 are the voltage stabilizing chip, and U4 is a communication chip; IC1A, IC2A, IC6A, IC7A, IC6B are inverter, and IC3 is the D/A conversion chip, and IC4 is the Voltage Reference chip; IC5 is a clock chip, and IC6 is a storage chip, and IC2A, IC2B, IC10A are amplifier.

Embodiment

Be elaborated below in conjunction with the technical scheme of accompanying drawing to the utility model:

The control circuit of Electric Motor Soft-starter as shown in Figure 1 comprises: microprocessor, three-phase voltage zero passage sample circuit, thyristor conduction detection circuit, thyristor gating circuit, three-phase current sample circuit, analog current output circuit, signal input circuit, signal output apparatus, telecommunication circuit, keyboard and LCD LCD, radiator temperature testing circuit, clock circuit, memory, PTC protective circuit, reset circuit.

Three-phase voltage zero passage sample circuit, thyristor conduction detection circuit, thyristor gating circuit, three-phase current sample circuit, analog current output circuit, signal input circuit, signal output apparatus, telecommunication circuit, keyboard are connected with microprocessor respectively with LCD LCD, radiator temperature testing circuit, clock circuit, memory, PTC protective circuit, reset circuit.Power circuit is each functional module power supply in microprocessor and the microprocessor peripheral circuit.

Thyristor break-make testing circuit is as shown in Figure 2: thyristor conduction detection circuit comprises first to fourth resistance R 1, R2, R3, R4, and first capacitor C 1, first bridge heap B1, first isolate optocoupler BR1 (model 6N139).The anode of thyristor to be detected is connected with an end of first resistance R 1; One utmost point of the other end of first resistance R 1, first capacitor C 1 is connected with first ac voltage input of first bridge heap B1 respectively; Another utmost point of first capacitor C 1, the negative electrode of thyristor to be detected are connected with second ac voltage input of first bridge heap B1 respectively, and the positive polarity dc voltage output end and first of first bridge heap B1 is isolated the positive input terminal (IN of optocoupler BR1 ⁺) connect, the negative polarity dc voltage output end and first of first bridge heap B1 is isolated the negative input end (IN of optocoupler BR1 ^-) connect; The two ends of second resistance R 2 are connected with power end (V), the voltage source V CC of the first isolation optocoupler BR1 respectively; The two ends of the 3rd resistance R 3 are connected with output reference end (E), the earth of the first isolation optocoupler BR1 respectively; The two ends of the 4th resistance R 4 are connected with the output (C) that voltage source V CC, first isolates optocoupler BR1 respectively, and first isolates earth terminal (G) ground connection of optocoupler BR1.Thyristor conduction detection circuit is used to detect the break-make situation of certain phase thyristor, when microprocessor receives the high level of thyristor conduction detection circuit output, expression the full conducting of the thyristor of surveying.

Signal input circuit is as shown in Figure 3: signal input circuit comprises: the 5th resistance R 5, the 6th resistance R 6, the first piezo-resistance RV1, second capacitor C 2, the first optocoupler O1 (model P181), the first interface J1.One end of the 5th resistance R 5 is connected with voltage source V CC; The I/O interface of the other end of the 5th resistance R 5, microprocessor is connected with the collector electrode of the first optocoupler O1 respectively; The grounded emitter of the first optocoupler O1; The anode of the first optocoupler O` is connected with an end of the 6th resistance R 6; The end of one utmost point of the other end of the 6th resistance R 6, second capacitor C 2, the first piezo-resistance RV1 is connected with No. 2 pins of the first interface J1 respectively, and the other end of another utmost point of second capacitor C 2, the negative electrode of the first optocoupler O2, the first piezo-resistance RV1 is connected with the earth respectively, and No. 1 pin of the first interface J1 connects the 24V direct voltage source.Signal input circuit is used to gather external control signal, converts the discernible signal of microprocessor to through signal input circuit, sends into microprocessor.This signal input circuit can be used as starting or stop signal input circuit; Also can be used as the programmable signal input circuit; Programmable signal is meant that microprocessor can be set to emergent stop signal, reset signal, crawl signal etc. by this input signal, to satisfy requirements of different users.

Signal output apparatus is as shown in Figure 4: comprising: the 7th resistance R 7, the second optocoupler O2, the first triode Q1 (model 9012), the first diode D1, the first relay R L1.The two ends of the 7th resistance R 7 are connected with the anode of voltage source V CC, the second optocoupler O2 respectively; The negative electrode of the second optocoupler O2 is connected with the I/O interface of microprocessor; The collector electrode of the second optocoupler O2 is connected with the base stage of the first triode Q1; The collector electrode of the emitter of the second optocoupler O2, the first triode Q1 is ground connection all; The two ends of the first relay R L1 are connected with the two poles of the earth of the first diode D1 respectively, and the anode of the first diode D1 is connected with the emitter of the first triode Q1, and the negative electrode of the first diode D1 connects+the 12V voltage source.Microprocessor output control signal OUT1, through light lotus root O2, triode Q1 control relay RL1 closes, divides, and this circuit is used for by-passing signal output, and run signal output circuit and fault-signal output circuit also are like this.Little processing can these be exported signal and be set to promptly realize programmable function like overload fault signal output, the output of open phase fault signal, the output of stall fault-signal or the like, can satisfy requirements of different users.

Telecommunication circuit is as shown in Figure 5: comprising: the 8th to the 17 resistance R 8--R17, communication chip U4 (model of U4 is MAX1480), the 3rd capacitor C 3, the 4th capacitor C 4, inverter ic 6A (model 74HC86), IC7A (model 74HC86), IC6B (model 74HC86).The two ends of the 8th resistance R 8 are connected with external communication interface A, B respectively; The two ends of the 9th resistance R 9 are connected with RO DRV end, the LED end of communication chip U4 respectively; The two ends of the tenth resistance R 10 are connected with B end, the COM2 end of communication chip U4 respectively; The two ends of the 11 resistance R 1 are connected with A end, the IVCC2 end of communication chip U4 respectively; The two ends of the 12 resistance R 12 are connected with DIIN end, the IVCC2 end of U4 respectively, and the two ends of the 13 resistance R 13 are connected with DEIN end, the IVCC2 end of U4 respectively, and the two ends of the 14 resistance R 14 are connected with the DI end of U4, No. 3 ports of IC6A respectively; The two ends of the 15 resistance R 15 are connected with the DE end of U4, No. 3 ports of IC7A respectively; The two ends of the 16 resistance R 16 are connected with the COM2 end of external communication interface SH, U4 respectively, and

end of an end of the 17 resistance R 17, MAX1480 is connected with No. 2 mouths of IC6B respectively, and No. 1 mouth of the other end of the 17 resistance R 17, IC6B is connected with voltage source respectively; The positive pole of the 3rd capacitor C 3 is connected with the VCC2 of U4 end; The minus earth of the 3rd capacitor C 3, the two poles of the earth of the 4th capacitor C 4 respectively with the VCC5 of U4 end, be connected, the A of U4, B end are connected with external communication interface A, B respectively; The DIIN end of U4 is connected with the DIDRV end; The DEIN end of U4 is connected with the DEDRV end, and the IVCC1 end of U4 is connected with the IVCC2 end, and the COM1 end of U4 is connected with the COM2 end; First to the 5th power input VCC1-VCC5 of U4 is connected with voltage source V CC, the SD end of U4, earth terminal ground connection.Telecommunication circuit is used to realize communicating by letter of soft initiator and host computer, realizes remote control, remote regulating, remote measurement, remote signalling.

Clock circuit is as shown in Figure 6: comprising: the 18 resistance R 18, battery BT, crystal oscillator CT, clock chip IC5 (model DS1305).Second source input (VCC2) ground connection of IC5; The battery supply incoming end (VBAT) of IC5 is connected with the positive pole of battery BT; Battery BT minus earth; Two crystal oscillator source incoming ends (X1, X2) of IC5 are connected at the two poles of the earth with crystal oscillator CT respectively, the earth terminal of IC5 (GND) ground connection, and the clock module modulated terminal (SERMODE) of IC5, internal logic device feeder ear (VCCIF), the first voltage source input (VCC1) are connected with voltage source V CC; The two ends of the 18 resistance R 18 are connected with the middle broken ends of fractured bone (INT0) of VCC voltage source, IC5 respectively; The SDI end input clock date signal SI of IC5, SDO end output clock date signal SO, SCLK end input clock signal SCK.RESET is IC5 power-fail output signal.Clock circuit record motor fault sends fault moment information to microprocessor constantly.

The PTC protective circuit is as shown in Figure 7: comprising: the 19 to 26 resistance R 19-R26, the 6th to the 8th capacitor C 6-C8, amplifier IC10A (model LM2904), PTC resistance, the second diode D2.One utmost point of the 5th capacitor C 5 is connected with an end of the 19 resistance R 19; Another utmost point ground connection of the 5th capacitor C 5; The other end of the 19 resistance R 19 is connected with an end of the 20 resistance R 20, an end of the 21 resistance R 21, the output of amplifier IC10A respectively; The other end ground connection of the 20 resistance R 20; The other end of the 21 resistance R 21 is connected with the negative input end of amplifier IC10A; The positive input terminal of amplifier IC10A is connected with a utmost point of the 6th capacitor C 6, an end of the 22 resistance R 22; Another utmost point ground connection of the 6th capacitor C 6; The other end of the 22 resistance R 22 is connected with an end of the 23 resistance R 23, a utmost point of the 7th capacitor C 7, and the other end of the 23 resistance R 23 is connected with an end of the 24 resistance R 24, the negative electrode of the second diode D2, an end of the 25 resistance R 25, and an end of the 26 resistance R 26 is connected with a utmost point of the other end of the 25 resistance R 25, the 8th capacitor C 8, an end of PTC resistance; The other end of another utmost point of the other end of PTC resistance, the 8th capacitor C 8, the anode of the second diode D2, the 24 resistance R 24, another utmost point ground connection of the 7th capacitor C 7, the other end of the 26 resistance R 26 is connected with voltage source V CC.In the PTC protective circuit; Generally that PTC resistance is pre-buried in motor windings, its typical action value is 3K, and this circuit converts the variation of resistance value into the variation of aanalogvoltage; Microprocessor is gathered analog voltage signal, and cutoff thyristor is realized protection when detected voltage signal surpasses set point.

Power circuit is as shown in Figure 8, and the external auxiliary power supply is through the first transformer T1 step-down, respectively through the 3rd, the 5th bridge heap B3, B5 rectification, more respectively through the first, the 3rd voltage stabilizing chip U1, U3 output dc voltage VCC (5V), 24V.In addition, the external auxiliary power supply is through the second transformer T2 step-down, through the 4th bridge heap B4 rectification, again through the second voltage stabilizing chip U2 output dc voltage 12V.The VCC power supply is control circuit power supplies such as microprocessor, and the 24V power supply is power supplies such as signal input circuit, telecommunication circuit, and 12V is power supplies such as relay.

The voltage zero-cross sample circuit is as shown in Figure 9, and the in-out end of a certain phase thyristor reason is respectively K1, K2, and 2 pin and the N line of second bridge heap B2 link, and N is the three-phase common port.3,4 pin of second bridge heap B2 are connected to 2,3 pin of the second isolation light lotus root BR2, and second isolates the 5 pin ground connection of light lotus root BR2, and 6 pin of the second isolation optocoupler BR2 are zero passage sampled signal INA, connect the INA pin of single-chip microcomputer.The oversampled circuit theory of each phase voltage is identical.Be example mutually with A now: when A phase voltage zero passage, INA will export a narrow pulse signal, and deliver to microprocessor.The sequencing of three-phase voltage zero cross signal has been confirmed the phase sequence of three-phase, if the voltage zero-crossing signal order is A, C, B, then voltage phase sequence is A, B, C.

Thyristor gating circuit is shown in figure 10; The thyristor gating circuit of A, B, C three-phase is identical; Be that example describes mutually with A below, thyristor triggering signal TFA is sent in little processing, connects the 4th through reverser IC1A and isolates 1 pin of light at a distance from BR4; 2 pin of the 4th isolation optocoupler BR4 are connected to 1 pin of the 3rd isolation optocoupler BR3, and 2 pin of the 3rd isolation optocoupler BR3 are through current-limiting resistance ground connection.The soft starter major loop comprises three groups of thyristors; Every group of thyristor is made up of the thyristor of two reverse parallel connections, and K1, G1 connect the anode and the control utmost point of forward thyristor respectively, and K2, G2 connect the anode and the control utmost point of reverse thyristor respectively; K1 connects power supply, and K2 connects motor.K1 is connected to the 4th through diode, resistance and isolates 6 pin of light at a distance from BR4, and 6 pin that 4 pin and the 3rd of the 4th isolation optocoupler BR4 are isolated optocoupler BR3 are connected, and 4 pin of the 3rd isolation optocoupler BR3 connect and compose the conducting loop through resistance and G2; K2 is connected to the 3rd through diode, resistance and isolates 4 pin of light at a distance from BR3, and 4 pin that 6 pin and the 4th of the 3rd isolation optocoupler BR3 are isolated optocoupler BR4 are connected, and 6 pin of the 4th isolation optocoupler BR4 connect and compose the conducting loop through resistance and G1.The break-make in above-mentioned two loops is controlled by triggering signal TFA.

Two parallelly connected with 4,6 pin of BR3, BR4 respectively resistance play all pressure effects.

Current sampling circuit is shown in figure 11, and the three-phase current sample rate current is identical, is that example describes mutually with A below.A phase current mutual inductor signal is connected to load resistance after the 6th bridge heap B6 rectification; Current loading signal on the load resistance is exported signal Ia to microprocessor through the follower of amplifier IC2A and peripheral circuit composition thereof again through the ratio amplifying circuit output of amplifier IC2B and peripheral circuit composition.Electric capacity strobes.

4-20mA analog current output circuit is shown in figure 12, and the 2nd, 3,4 pin of D/A conversion chip IC3 are connected with microprocessor, and the 6th pin of IC3 is connected with the 2nd pin of Voltage Reference chip IC 4; The 7th pin ground connection of IC3, the 8th pin of IC3 meets VCC, and the 1st pin of IC3 connects the control utmost point of metal-oxide-semiconductor; The 5th pin of IC3 connect metal-oxide-semiconductor source electrode; As the analog current feedback signal, the drain electrode of metal-oxide-semiconductor connects an end of load resistance, and the source electrode of metal-oxide-semiconductor is through current-limiting resistance ground connection.The other end of load resistance is connected with 24V.What flow through in the load resistance is 4～20mA electric current, and electric capacity is filter capacitor.

The radiator temperature testing circuit is shown in figure 13; Temperature switch is connected with control circuit through the second interface J2, and temperature switch is passive contact signal, and this signal is exported signal P04 to microprocessor after the 3rd smooth lotus root O3 isolates; Resistance plays metering function, and electric capacity strobes.When radiator temperature surpassed 80 ℃, microprocessor received a low level signal, and it is overheated promptly to detect radiator, thereby forbids the thyristor output voltage, and the protection thyristor is overheated and damage.

Memory circuit is shown in figure 14: IC6 is memory chip AT25640, and P60 is the chip selection signal of memory chip IC6, controlled by microprocessor, and storage chip IC6 and microprocessor communicate with the communication protocol of SPI through SI, SO, SCK signal.

Reset circuit is shown in figure 15, and reset circuit adopts the mode of rc reset to realize resetting, and reduces circuit cost.

The foregoing description only is the technical conceive and the characteristics of explanation the utility model, and its purpose is to let the personage who is familiar with this technology can understand content of the utility model and enforcement according to this, can not limit the protection range of the utility model with this.All equivalences of being done according to the utility model spirit change or modify, and all should be encompassed within the protection range of the utility model.

Claims

1. the control circuit of an Electric Motor Soft-starter; It is characterized in that, comprising: microprocessor, three-phase voltage zero passage sample circuit, thyristor conduction detection circuit, thyristor gating circuit, three-phase current sample circuit, analog current output circuit, signal input circuit, signal output apparatus, telecommunication circuit, keyboard and LCD LCD, radiator temperature testing circuit, clock circuit, memory, PTC protective circuit, reset circuit;

2. the control circuit of Electric Motor Soft-starter according to claim 1 is characterized in that: said thyristor conduction detection circuit comprises that first to fourth resistance, first electric capacity, first bridge heap, first isolate optocoupler;

3. the control circuit of Electric Motor Soft-starter according to claim 1 is characterized in that said signal input circuit comprises: the 5th resistance, the 6th resistance, first piezo-resistance, second electric capacity, first optocoupler, first interface;

4. the control circuit of Electric Motor Soft-starter according to claim 1 is characterized in that said signal output apparatus comprises: the 7th resistance, second optocoupler, first triode, first diode, first relay;

5. the control circuit of Electric Motor Soft-starter according to claim 1 is characterized in that said telecommunication circuit comprises: the 8th to the 17 resistance, MAX1480, the 3rd electric capacity, the 4th electric capacity, first inverter, second inverter, the 3rd inverter;

Figure 201220070386X100001DEST_PATH_IMAGE001

6. the control circuit of Electric Motor Soft-starter according to claim 1 is characterized in that said clock circuit comprises: the 18 resistance, battery, crystal oscillator, DS1305;

7. the control circuit of the soft initiator of motor according to claim 1 is characterized in that said PTC protective circuit comprises: amplifier, PTC resistance;