CN2193623Y

CN2193623Y - Contactless constant current starter for motor

Info

Publication number: CN2193623Y
Application number: CN 94217011
Authority: CN
Inventors: 袁守民
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-07-02
Filing date: 1994-07-02
Publication date: 1995-03-29
Anticipated expiration: 2004-07-02

Abstract

The utility model relates to a contactless constant current starter for a motor. A full closed ring current adjusting feedback system is composed of a constant current given circuit, a constant current soft start circuit, a level regulator, a comparator, a trigger, a thyristor and a current detect combination circuit, the electric current of the motor is boosted from zero stepless to the constant current specified value, and is accelerated under the constant value until the terminal voltage and the rotary speed of the motor reach the rated value; the current start circuit automatically disengages because of an isolating circuit, and the motor enters a power-saving operating mode. The starter is provided with a zero load, a light load automatic detection circuit and a phase-absent over current protection circuit. The utility model adopts full electronic circuits, the structure is simple, the constant current start of the motor is realized, the load change of the motor can be automatically tracked, and the terminal voltage of the motor can be continuously adjusted.

Description

Contactless constant current starter for motor

The utility model relates to a kind of motor constant flow starting device, the contactless economize on electricity constant flow starting of particularly a kind of full electronic closed loop device.

Starting current for the restriction alternating current motor, the tradition reduced voltage starter generally adopts the starter of Electromagnetic Control, as Y-Δ starter, from lotus root compensator etc., the problem that exists is that equipment volume is big, self power consumption is big, make and break contact is easy to generate electric spark and the secondary changing-over is impacted, continuously Fraquent start.

Some electronic controllers have appearred in recent years, as the patent No. is 89202490.9 disclosed a kind of electricity-saving controllers, adopt starting amplifier output ramp velocity to change, voltage is progressively risen, its weak point is that electric current can not get effective restriction, and at the beginning of starting, produce shake in various degree inevitably, even rise and dash counter-rotating, electromechanical equipment is had a significant impact useful life.And for example the patent No. is 91230559.1 a kind of motor soft starters of introducing, its starting voltage is oblique ascension in time, terminal voltage of motor rises to full voltage with linear gradient within the predetermined time, and this starter can not change from the motion tracking motor load, and it is undesirable to start power savings.The patent No. is the contactless computer festival electric starter of motor of 92208916.7 records for another example, the soft start of motor is the control signal that changes by certain ramp rate by Single Chip Microcomputer (SCM) program control output, connect the starter speed selector switch on the input of single chip, according to the selected voluntarily given startup rate controlled degree of the bringing onto load situation user of motor institute.This starter can only change from the motion tracking motor load under the startup speed of setting, and artificially selects rate switch to change according to motor load and sets optimum start-up speed.

The utility model has overcome the deficiency of above-mentioned prior art, its purpose is to design a kind of simple in structure, dependable performance, has the contactless economize on electricity constant flow starting of the motor device that the full cut-off circular current is regulated reponse system, load variations from the motion tracking motor, adjust terminal voltage of motor continuously, make motor under given starting current, the constant flow starting motor.

Narrate the technical solution of the utility model below.

A kind of motor is contactless economize on electricity constant flow starting device, comprise given constant current full cut-off circular current adjusting reponse system, it is characterized in that said Current Regulation reponse system is electrically connected by principal of constant current soft circuit, level regulator, comparator, trigger, thyristor and current detector forms, the principal of constant current soft circuit provides a soft start signal, by level regulator, comparator, trigger, thyristor and current detector, make motor current by the zero stepless given electric current that rises to.This short time soft start can reduce the impact to motor and electrical network.When current of electric rises to set-point, current feedback system by the full cut-off ring, it is constant to make starting current maintain set-point accurately, and motor quickens under constant starting current like this, and terminal voltage of motor rises gradually with the increase of rotating speed, but starting current is owing to the effect of closed loop feedback remains unchanged, reach rated speed until motor, electric current descends, when motor terminal voltage reaches rated value, the constant flow starting control circuit withdraws from automatically, and motor enters the power-saving running state.Thereby overcome starting technique in the past, by the artificial judgment starting state, or switch intrinsic with time delay timing, can not finish with the motor speed rising and from motion tracking and adjust motor terminal voltage, and guarantee the shortcoming of starting process by prolonging the starting time, thereby shortened the starting time, saved electric energy, improved work efficiency.

The utility model reduces active energy wastes such as a large amount of reactive current wastes of causing and iron loss, copper loss, line loss because of power factor for the motor underloading, when unloaded, adopt and detect motor voltage phase place and current and phase difference, adjust motor input current technical scheme, make motor under various load conditions, keep higher power factor, to reach meritorious, the reactive loss purpose of saving motor.Simultaneously, the utility model has been taked the relevant art safeguard measure for power supply phase shortage or over current of motor, utilizes the three phase mains electric current to sample and relatively differentiates, gets its difference and judges, the locking of cutting off the power supply.

The disclosed a kind of motor electricity saving constant flow starting device of the utility model, its unique distinction is following four aspects:

One, with the increase of motor starting rotating speed, automatically adjust the terminal voltage of motor, make motor constant flow starting under given starting current, its simple and reliable electronic type full cut-off circular current is regulated the bag feedback system, guarantee the accurate constant flow starting of impact that do not have, and guarantee that electrical network and running current are not had the impact impact, and make it fast stepless and increase to given reference constant current, realize principal of constant current soft.

Two, adopt the three-phase current difference to compare, judge, can carry out open-phase fault protection accurately under any ruuning situation of motor.

Three, has good inverse-time overcurrent protection characteristic.

Four, have light load and judge the size of current of adjusting input motor automatically, make motor improve power factor, thereby save meritorious, reactive energy, realize purpose of energy saving.

The utility model circuit can adapt to the bigger variation of line voltage automatically, and make in the starting process interference-free, full guard function and electricity-saving function with the various faults of motor.Its volume is little, reliability is high, is adapted to replace various old-fashioned motor starters.

Introduce the utility model below in conjunction with accompanying drawing.

Fig. 1 is a frame principle figure of the present utility model.

Fig. 2 is the utility model circuit theory diagrams.

Fig. 3 is the utility model load control circuit schematic diagram.

Fig. 4 is the utility model load regulating and controlling output circuit schematic diagram.

Fig. 5 is the utility model open-phase protection systematic square frame schematic diagram.

Fig. 6 is the utility model Over Current Protection System frame principle figure.

Fig. 7 is the utility model over-current protection for the phase lacks circuit theory diagrams.

The physical circuit schematic diagram as shown in Figure 2.HL is a current detector, forming signal by diode D1, D2, capacitor C 1, C2, C3, resistance R 1, R2, R3 takes out and filter circuit, form the constant current feedback circuit by resistance R 4, R5, R6, capacitor C 4, proportional and integral controller A1, connection is formed soft starting circuit by resistance R 7, capacitor C 5, and above-mentioned each circuit bank is helped closed loop current and regulated reponse system.Behind the given circuit proceed-to-send,, above-mentioned Current Regulation reponse system is withdrawed from automatically by the starting operation buffer circuit that resistance R 9, diode D3 form.When promptly starting, the constant current control signal is may cross diode D3; Proceed-to-send, D3 stop constant current signal to pass through.When constant flow starting, given starting current signal is provided with actual current by R8 and compares, and by proportional and integral controller A1 output, compares with sawtooth waveforms again, by the suitable trigger voltage of level regulator A2 output, make the electric current that flows through motor keep a steady state value.Thereby guaranteed soft start → constant flow starting → enter automatically best motor starting procedure of power save mode.

Alternating current motor is when unloaded and underloading, power factor is lower, cause the waste of active energies such as a large amount of reactive current wastes and iron loss, copper loss, line loss, the design's technical scheme only detects the load behavior of motor at any time with simple circuit, by adjusting the input current of motor, make motor under various load conditions, higher power factor is all arranged, to reach meritorious, the reactive loss of saving motor.

Frame principle figure such as Fig. 1, when the motor underloading, the voltage-phase of motor and current phase differ bigger, detect the loading condition of motor, just phase place extent by voltage-phase detector G and current phase detector S.Adjust the size that thyristor outputs to motor voltage by level regulator A2 output one control voltage control trigger voltage again.When phase difference was big, output voltage was low, when phase difference hour, output voltage is higher, thereby has reduced motor at underloading and the running current when unloaded, has improved the power of electric motor factor.Physical circuit schematic diagram such as Fig. 3.Only get A among the figure and be example mutually, all the other two-phases are identical.A3 is the voltage square wave detector among the figure, and A4 is an electric current square wave detector, and when the motor underloading, power factor is lower, and the electric current square wave lags behind voltage square wave.Flow through N1, R14 of A3, A4 resultant current locates to export square wave mean value at the phototriode N1 ' of photoisolator N1, transform to the negative voltage direction, the adjuster of being made up of A5 makes negative trigger voltage the reactive current of the motor of flowing through reduce, thereby reaches the purpose of economize on electricity.R18 and R19 make up among the figure, are used to adjust the size of amount of electricity saving, and N1, N1 ' photoelectrical coupler are used to transmit the amount of phase difference of voltage and current, play the buffer action of power supply simultaneously.

Present design can finish simultaneously alternating current motor from whole starting process up to various running status processes, no matter be the motor current imbalance that a variety of causes such as power supply phase shortage or motor windings be bad cause, protect fast and accurately.The protection of crossing streaming system is the inverse-time overcurrent protection system that allows momentary overload and some production occasion needs short cycle overload to design according to motor; it is extremely unreliable that this technology has overcome open-phase protection and the action influenced by ambient temperature of mechanical type thermal overload protection device that can not carry out motor starting procedure in the prior art; particularly prior art is carried out open-phase protection by thermal relay; because metal fever inertia is very big; so in most open-phase faults; can not effectively protect motor to burn out; the technical characterstic of this open-phase protection system is to adopt the three phase mains electric current to sample relatively to differentiate; get its difference; when difference surpasses permissible value; the locking of promptly cutting off the power supply; and output phase shortage shows signal; select for use the high-gain amplifier to carry out filtering relatively; reliable in action; speed is fast, can carry out open-phase fault protection in any case, and the protection accuracy of action is not subjected to the influence of environment.Its functional-block diagram such as Fig. 5.The Over Current Protection System principle is: compared by current sampling signal and adjustable given 1,2 times of specified overcurrent signal.When the sample rate current signal surpasses given thresholding; begin charging system is carried out converting charge; it is big more to flow through multiple; the corresponding increase of charging current is through after a while, when charging voltage reaches the overcurrent threshold voltage; overcurrent protection is promptly moved; and self-locking cuts off the electricity supply, and exports an over-current signal simultaneously, frame principle figure such as Fig. 6.Over-current protection for the phase lacks circuit theory diagrams such as Fig. 7, T1, T2, T3 and peripheral cell form differential amplification comparison circuit.Work as A; B; when C three-phase sample rate current signal equates; T1; T2; T3 collector electrode non-output signal; work as A; B; the C three-phase current signal has arbitrary phase current to reduce or when not having; this moment, motor was in the failure operation state; then differential wave is by R33; R34; the filter circuit that C33 forms is sent into the signal that adjuster A7 negative input end and given permissible error potentiometer R35 provide and is compared; when surpassing the permissible error current potential; adjuster A7 upset; export a low level; and pass through R36; the D32 self-locking, phase shortage indication LED 2 is lighted, the locking of open-phase protection output simultaneously trigger impulse; the motor outage reaches the motor phase failure protection purpose.The inverse-time overcurrent protection system is made of adjuster A8 and peripheral cell thereof.When motor overload (this moment, the three-phase balance phase shortage was failure to actuate); overload current signal is charged to C34 through R41; overload magnification is big more; charging current is big more; then A8 input negative terminal current potential rises fast more; when permission overload current multiple that the current potential on the C34 provides greater than R40; the A8 upset; light LED3 overcurrent clearing lamp simultaneously; and export an overcurrent protection voltage through D35, the locking trigger impulse turn-offs motor power; A8 realizes self-lock protection by R39, D34 equally, till fault is got rid of start again.Foregoing circuit is simple in structure, and circuit is reliable, and anti-interference is extremely strong, has been realized the accurate action protection of the motor phase shortage over current fault that any reason causes by open-and-shut circuit.

Claims

1, the contactless economize on electricity constant flow starting of a kind of motor device, comprise given constant current full cut-off circular current adjusting reponse system, it is characterized in that said Current Regulation reponse system is electrically connected by principal of constant current soft circuit, level regulator, comparator, trigger, thyristor and current detector forms, the principal of constant current soft circuit provides a soft start signal, by level regulator, comparator, trigger, thyristor and current detector, make motor current by the zero stepless given electric current that rises to.

2, constant flow starting device according to claim 1, it is characterized in that said full cut-off circular current adjusting reponse system connects diode D1, D2 by current detector HL, capacitor C 1, C2, C3 and resistance R 1, R2, R3 form signal and take out and filter circuit, by resistance R 4, R5, R6, capacitor C 4 and proportional and integral controller A1 form the constant current feedback circuit, connect the soft starting circuit of being made up of resistance R 7 and capacitor C 5.

3, constant flow starting device according to claim 1 and 2 is characterized in that said full cut-off circular current is regulated to be provided with the starting operation buffer circuit that resistance R 9 and diode D3 form in the reponse system.

4, constant flow starting device according to claim 1 and 2 is characterized in that said constant flow starting circuit by resistance R 8 given starting current signals, by proportional and integral controller A1 output, compares by level regulator A2 trigger output voltage with sawtooth waveforms.

5, constant flow starting device according to claim 1 is characterized in that being connected with voltage-phase detector and current phase detector in said level regulator A2 and the comparator circuit, by the phase difference detection motor load.

6, constant flow starting device according to claim 5, it is characterized in that said voltage-phase detector adopts voltage square wave detector A3, the current phase detector adopts electric current square wave detector A4, the two resultant current carries out the filtering adjustment through photoisolator N1, resistance R 14 by adjuster A5, export the direct-current control voltage relevant, the control trigger voltage with load.

7, constant flow starting device according to claim 1, it is characterized in that said starter circuit phase shortage test section adopts the comparison of sampling of three phase mains electric current, form differential amplification comparison circuit by T1, T2, T3 and peripheral cell, the signal that filter circuit input regulator A3 negative input end that its differential wave is made up of resistance R 33, R34 and capacitor C 33 and given permissible error potentiometer R35 provide compares, exceed the permissible error current potential, adjuster A7 upset output one low level is by resistance R 36 and diode D32 output locking trigger impulse.

8, constant flow starting device according to claim 1; it is characterized in that said starter circuit over-current detection part is made of adjuster A8 and peripheral cell thereof; overload current signal is charged to capacitor C 34 through resistance R 41; adjuster A8 input negative terminal current potential is risen; when capacitor C 34 current potentials during greater than the given permission overload current multiple of resistance R 40; adjuster A8 upset, and through overcurrent protection voltage of diode D35 output, locking trigger impulse.

9, constant flow starting device according to claim 8 is characterized in that said overload current adjuster A8 realizes self-lock protection by resistance R 34 and diode D34.

10,, it is characterized in that said phase shortage test section and over-current detection partly are respectively equipped with phase shortage indicator light LED2 and overcurrent indicator light LED3 according to claim 7 or 8 described constant flow starting devices.