CN2624520Y

CN2624520Y - Motor soft starter

Info

Publication number: CN2624520Y
Application number: CN 03222163
Authority: CN
Inventors: 陈主成
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-05-21
Filing date: 2003-05-21
Publication date: 2004-07-07
Anticipated expiration: 2013-05-21

Abstract

A motor soft starter is provided, each phase power supply loop of motor comprises a rectifying circuit 3, a chopper and voltage regulating circuit 4, a pulse waveform generating circuit 1, and also comprises a sine-wave collecting circuit 6, a AGC control and driving circuit 7, a voltage resultant and a power amplifying circuit 5; the output of the chopper and voltage regulating circuit 4 can be connected to the drain of high power push pull amplifier tube in the voltage resultant and the power amplifying circuit 5 after an LC loop filter, both high power push pull amplifier tubes and a driving transformer B2, an output coupling transformer B1 form a push pull voltage resultant and power amplifying circuit; the output end of two high power push pull amplifier tubes has the isolating output through the output coupling transformer B1, and connected with motor in series, then connected with the input end of AC grid. The output of the utility model has the same frequency and phase with that of grid with no ''burr'' sine voltage, and is isolated with the grid; the size of the output voltage can be adjusted as required.

Description

Motor soft starter

Technical field

The utility model relates to a kind of protective device of electric motor starting.

Background technology

At present, the prior motor soft initiator has been used switching circuit, and output voltage is as the soft start voltage of motor.But the defective of this technology has 3 points: the output voltage of (1) switching circuit is not smooth sine wave, but the voltage waveform of " burr " is arranged; This burr voltage can reduce the life-span of motor widely.(2) maximum output voltage of switching circuit is the input voltage of AC power; Because the restriction of power electronic device withstand voltage at present, the output voltage of this circuit can not surpass 380V; This technology can not be applied to the motor of the above power supply of 380V like this.(3) switching circuit directly connects with motor, is not isolation coupling, and many shortcomings are arranged; For example: switching device very easily damages; Reason is a shutdown moment, and the back-pressure of motor coil induction very easily punctures switching device; Though can solve it with buffering and freewheeling circuit for low-power machine, for more powerful motor, the volume ratio of buffer circuit is bigger.

Summary of the invention

The purpose of this utility model proposes a kind of output in order to overcome the above problems exactly, can eliminate the harmonic wave in the soft initiator output voltage in the past; Output voltage can be greater than the motor soft starter of the input voltage of AC power.

The technical solution of the utility model is achieved like this: a kind of motor soft starter, every phase current supply circuit of motor includes the rectification circuit 3 that line voltage is carried out rectification, pulsating voltage behind the bridge rectifier is carried out the voltage regulation circuit of chopping 4 of chopper control, the impulse waveform that the pulse duty factor of control voltage regulation circuit of chopping 4 can reduce automatically produces circuit 1, be characterized in: it also comprises from the electrical network input takes the sine wave of continuation sinusoidal to take circuit 6, be subjected to voltage signal control and the AGC control and the promotion circuit 7 that the offset of sinusoidal ripple takes the sine voltage signal of circuit 6 to amplify of taking-up from voltage regulation circuit of chopping 4, the voltage that is promoted the circuit output signal excitation synthesizes and power amplification circuit 5; The output of voltage regulation circuit of chopping 4 behind the LC loop filter, be connected to voltage synthetic with power amplification circuit 5 in high-power drain electrode of recommending amplifier tube, two high-power amplifier tubes of recommending have been formed the voltage of recommending and have been synthesized and power amplifier with driving transformer B2, output coupling transformer B1; The outputs that two high-power recommends amplifier tube are isolated output through output coupling transformer B1, and the input of incoming transport electrical network afterwards of connect with motor.

Output of the present utility model is and the sinusoidal voltage of electrical network same frequency, same-phase, nothing " burr ", voltage synthetic with power amplifier with transformer isolation coupling output, discord motor and motor power supply grid directly connect, and have avoided the phase mutual interference; The big I of output voltage changes the primary coil of output transformer as required and the turn ratio of secondary coil is a scalable.

Description of drawings:

Fig. 1 is circuit theory diagrams of the present utility model.

Fig. 2 is the block diagram of monophase machine soft initiator.Among the figure: the BX-fuse; J _1-1, J _1-2The normally-closed contact switch of-delayed start-up; J _2-1The normally opened contact switch of-timing closing; R1 to R10-resistance; BZ-rectifier bridge heap; The T1-MOSFET pipe; T2, T3-IGBT pipe; T4-automatic gain control (AGC) pipe; The L-inductance; C1, C2-electric capacity; D1, D2-diode; The M-motor; B1-exports coupling transformer; The B2-driving transformer; The IC-LM1875 power discharging integrated block; The 1-impulse waveform produces circuit; 2-Hall voltage transducer; The 3-rectification circuit; The 4-voltage regulation circuit of chopping; Synthetic and the power amplification circuit of 5-voltage; The 6-sine wave is taked circuit; 7-AGC control and promotion circuit.

Embodiment

Circuit working principle of the present utility model is: incoming transport power supply after coil of stator of motor is connected with variable voltage source; As long as variable voltage source is and electrical network same frequency, synchronous sinusoidal voltage that the voltage swing that changes variable voltage source so just can change the suffered voltage swing of motor.The variable voltage source amplitude drops to zero gradually from line voltage during startup, and electric moter voltage rises to line voltage gradually from zero.So just realized the soft start of motor.

From Fig. 2 as seen, the AC-input voltage of electrical network is delivered to voltage regulation circuit of chopping 4 after rectification circuit 3 is rectified into sine " steamed bun " ripple, and the impulse waveform that the pulse duty ratio can reduce automatically during startup produces the output voltage amplitude of circuit 1 control voltage regulation circuit of chopping 4; The output voltage of voltage regulation circuit of chopping 4 after filtering as voltage synthetic with power amplification circuit 5 in the drain power of device for power switching, the size of this voltage is directly proportional with the duty ratio of input pulse; The sine voltage signal takes circuit 6 to deliver to AGC control and to promote circuit 7 from the continuation sinusoidal that input is taked continuously, through promote and excitation after deliver to the gate pole control end of the synthetic device for power switching with power amplification circuit 5 of voltage, voltage is synthetic to synthesize-individual complete sine wave with the half-sinusoid of power amplification circuit 5 after two rectifications, has carried out power amplification simultaneously again.The output voltage of this circuit is connected with coil of stator of motor and is inserted electrical network, and output voltage reduces gradually, and electric moter voltage just can increase gradually.

From Fig. 1 as seen, the grid alternating current of input passes through the normally-closed contact switch J of delayed start-up behind fuse BX _1-1Deliver to rectifier bridge heap BZ and be rectified into " steamed bun " ripple, the input of piling at rectifier bridge is connected to the sinusoidal continuous signal bleeder circuit of being connected with R2 by resistance R 1; Rectification output end has been connected to the drain electrode of the MOSFET pipe T1 of chopper control effect, the pulse signal that the impulse waveform that pulse duty factor can reduce automatically produces circuit 1 is connected to the grid that MOSFET manages T1 after drive block amplifies, the output voltage amplitude of the duty ratio control MOSFET pipe T1 of grid input pulse; Impulse waveform produces circuit and can be realized by two 555 time-base integrated circuits; During electric motor starting, impulse waveform produces circuit 1 output duty of ratio and reduces gradually, and the copped wave output voltage also decreases, and promptly the output voltage in variable voltage source also decreases, just increase gradually with the voltage on the motor that variable voltage source is connected, so just realized soft start.

The source electrode of MOSFET pipe T1 after inductance L and capacitor C 1 filtering, be connected to voltage synthetic with power amplification circuit in the drain electrode of IGBT pipe T2; Hall voltage transducer 2 is measured the voltage signal between filter capacitor C1 ends A, B point, delivers to the base stage that AGC manages T4 by resistance R 4, the multiplication factor β value of control AGC pipe T4, and multiplication factor β value is directly proportional with the voltage signal values that Hall voltage transducer 2 is sent here; The sine voltage of AGC triode T4 output is directly proportional with duty of ratio.The base stage of AGC pipe T4 also is connected to the continuous sine voltage signal of being sent here by divider resistance R1, R2; The collector electrode of AGC pipe T4 is connected to+the 15V power supply by resistance R 5, and emitter is by resistance R 6 ground connection; Output signal is connected to the in-phase input end that model is the power amplifier integrate circuit IC of LM1875 by resistance R 7, is connected to the shunt circuit of feedback resistance R8 and vibrationproof capacitor C 2 between inverting input and the output, and the positive-negative power end of power discharging IC is connected to respectively+the 15V power supply.Power discharging IC is managed AGC after sinusoidal voltage that T4 sends here amplifies, and output is connected to an end of the primary coil of driving transformer B2, the other end ground connection of primary coil; The secondary coil two ends of driving transformer B2 are connected to the control gate pole of IGBT pipe T2, T3, the centre cap ground connection of the secondary coil of driving transformer B2 respectively through resistance R 9, R10; The drain electrode of IGBT pipe T2, T3 all is connected to filter capacitor C1 output voltage terminal A point; The source electrode of IGBT pipe T2, T3 is connected to the two ends of output coupling transformer B1 primary coil respectively, the centre cap ground connection of output coupling transformer B1 primary coil, the source electrode of the termination IGBT pipe T2 of the same name of primary coil, output coupling transformer B1, driving transformer B2, IGBT pipe T2 and T3 have formed the synthetic and power amplifier of the voltage of recommending; Be connected to afterflow protection diode D1, D2 between the drain electrode of IGBT pipe T2, T3 and source electrode respectively, the negative pole of diode D1, D2 links to each other with the drain electrode of IGBT pipe T2, T3 respectively; The end of the same name of output coupling transformer B1 secondary coil is by the normally-closed contact switch J of delayed start-up _1-2Be connected to an end of motor M stator winding, this end of stator winding is the normally opened contact switch J by timing closing also _2-1Be connected to the other end of output coupling transformer B1 secondary coil; The other end and the input two ends that are connected to AC network of this end of output coupling transformer B1 secondary coil and the stator winding of motor M.

Because sine wave is taked the power supply of the sine voltage signal of circuit from motor continuously, can guarantee that like this voltage synthesizes and the output voltage and the line voltage homophase of power amplification circuit.Two IGBT pipe T2, T3 conductings respectively in the positive-negative half-cycle of input sinusoidal signal, drive output coupling transformer B1 with the synthetic complete sine wave of two sines " steamed bun " ripple, output coupling transformer B1 secondary coil output variable voltage, electrical network is inserted in the back of connecting with motor, soft starting circuit and motor and motor power supply grid are isolated, and do not disturb mutually.During electric motor starting, the variable sinusoidal voltage of transformer B1 secondary coil output amplitude, magnitude of voltage reduces to zero gradually from line voltage, and the voltage on the motor just can increase gradually, rises to line voltage, has so just realized the soft start of motor.Behind the electric motor starting, available time-delay relay carries out circuit and switches the normally-closed contact switch J of delayed start-up _1-1, J _1-2All open the normally opened contact switch J of timing closing _2-1Closure, the motor power supply transfers the normal power supply state to.

Can replace time-delay relay to get final product by A.C. contactor or solid-state relay (SSR) for heavy-duty motor.

The soft starting circuit schematic diagram of monophase machine only draws among Fig. 1; For three phase electric machine, can form by three non-interfering three single-phase soft start loops.

Claims

1, a kind of motor soft starter, every phase current supply circuit of motor includes the rectification circuit (3) that line voltage is carried out rectification, pulsating voltage behind the bridge rectifier is carried out the voltage regulation circuit of chopping (4) of chopper control, the impulse waveform that the pulse duty factor of control voltage regulation circuit of chopping (4) can reduce automatically produces circuit (1), it is characterized in that: it also comprises from the electrical network input takes the sine wave of continuation sinusoidal to take circuit (6), be subjected to voltage signal control and the AGC control and the promotion circuit (7) that the offset of sinusoidal ripple takes the sine voltage signal of circuit (6) to amplify of taking-up from voltage regulation circuit of chopping (4), the voltage that is promoted the circuit output signal excitation synthesizes and power amplification circuit (5); The output of voltage regulation circuit of chopping (4) behind the LC loop filter, be connected to voltage synthetic with power amplification circuit (5) in high-power drain electrode of recommending amplifier tube, two high-power recommends amplifier tubes and has formed the voltage of recommending with driving transformer (B2), output coupling transformer (B1) and synthesize and power amplifier; The outputs that two high-power recommends amplifier tube are isolated output through output coupling transformer (B1), and the input of incoming transport electrical network afterwards of connect with motor.

2, a kind of motor soft starter according to claim 1 is characterized in that: it is the voltage signal that takes out control AGC control and promotion circuit (7) with the output voltage terminal of Hall voltage transducer (2) filter capacitor (C1) from voltage regulation circuit of chopping (4).

3, a kind of motor soft starter according to claim 1 and 2 is characterized in that: the first normally-closed contact switch (J that takes to be connected between circuit (6) delayed start-up at electrical network input and sine wave _1-1); Be connected to the first normally-closed contact switch (J of delayed start-up in the series side of the end secondary of the same name of exporting coupling transformer (B1) and motor stator _1-2), the normally opened contact switch (J that is connected to timing closing in the secondary other end and the series side of motor stator of output coupling transformer (B1) _2-1).