CN110022091A - Permanent torque starting and overload intelligent protection method and the device of a kind of direct current generator - Google Patents

Permanent torque starting and overload intelligent protection method and the device of a kind of direct current generator Download PDF

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Publication number
CN110022091A
CN110022091A CN201910308095.6A CN201910308095A CN110022091A CN 110022091 A CN110022091 A CN 110022091A CN 201910308095 A CN201910308095 A CN 201910308095A CN 110022091 A CN110022091 A CN 110022091A
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current
motor
overload
starting
voltage
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CN110022091B (en
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白海城
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Liaoning Shihua University
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Liaoning Shihua University
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02HEMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/08Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
    • H02H7/085Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load
    • H02H7/0855Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load avoiding response to transient overloads, e.g. during starting
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02PCONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P1/00Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/16Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
    • H02P1/18Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual dc motor
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02PCONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P29/00Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
    • H02P29/02Providing protection against overload without automatic interruption of supply
    • H02P29/024Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load
    • H02P29/028Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load the motor continuing operation despite the fault condition, e.g. eliminating, compensating for or remedying the fault

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Motor And Converter Starters (AREA)
  • Control Of Ac Motors In General (AREA)
  • Control Of Direct Current Motors (AREA)

Abstract

The present invention relates to a kind of starting of the permanent torque of motor drag and control technology field more particularly to separate excitation or permanent magnet direct current motor and overload intelligent protection method and device, which includes that current closed-loop adjusts unit, pulse-width regulated unit, control unit.The permanent torque starting control and overload intelligent protection of direct current generator are realized in the guard method by the detection of motor working current closed loop, pi regulator, PWM voltage control technology and current squaring decay algorithm.The present invention carries out scientific and reasonable protection to it with prestissimo clean boot motor and when motor moment overload occurs because of load disturbance in steady state operation during realizing Electric Traction; to under the premise of guaranteeing motor security application, improve the working efficiency of motor, the robustness of performance and electric drive system as far as possible.

Description

Permanent torque starting and overload intelligent protection method and the device of a kind of direct current generator
Technical field
The present invention relates to motor drag and control technology field more particularly to the perseverances of a kind of separate excitation or permanent magnet direct current motor Torque starting and overload intelligent protection method and device.
Background technique
In industrial and agricultural production, large and medium motor is widely applied to go to drag various manufacturing machine equipment as prime mover. In automatic field, various small-sized control motors are then widely by as detecting, zoom in and execute element.Dc motor conduct One important branch of motor field, due to its good speed adjustment features, speed-regulating range width and biggish torque and good starting Characteristic is widely applied in the modern life.
During Electric Traction, direct current generator is frequently necessary to start, and the basic demand of optimum start-up is that detent torque is most May shorten as far as possible greatly starting the time, while require to flow through the current control of armature again in a certain safe range in order to avoid Burn winding or damage mechanical equipment.Further, since the uncertainty of load or extraneous random disturbances, motor is during operation Instantaneous or short-time overload phenomenon can inevitably be generated.If overload impact electric current is larger but the duration is shorter, or overload continue when Between longer but dash current it is general, should ensure that at this time motor operate normally without stopping because frequently protecting.But work as dash current The larger and duration should take stop-working protection measure when relatively long in time, in order to avoid burn armature.This requires controls to be System should both have good robustness has scientific and reasonable overcurrent protection mechanism again.
The starting method of direct current generator can generally be divided into: directly initiate, string resistance stepped starting and armature reduced-voltage starting. It directly initiates and is exactly directly subject to voltage rating at armature both ends, since its starting current is very big, commutation spark will occurs and cause Commutation is difficult, it is also possible to cause the malfunction of overcurrent protective device, while easily make mechanical equipment impaired because detent torque is excessive.Electricity Resistance is sealed in armature circuit when pivot circuit in series resistance stepped starting starts, to reduce starting current Ist, work as electricity after starting Machine revolving speed cuts off resistance after rising to a certain value again, to guarantee enough detent torques.This method equipment is simple and can will start Current limit is in permissible range, but energy consumption is larger, should not be used in the large and medium-sized motor of frequent starting.In addition, with regard to working mechanism For, the detent torque that motor obtains in stepped starting mode is serrated distribution character at any time, can only switch wink in resistance Between reach best torque, not can guarantee and obtain constant torque in entire start-up course, thus be difficult to realize most opening fastly for motor Dynamic and smooth starting.It is lower that reduced-voltage starting method is that armature starting voltage tune obtains, as revolving speed rising is stepped up voltage, so that electric Pivot current limit is in a certain permissible range.This method energy loss is small, but must a set of dedicated voltage controller power source, investment compared with Greatly, and in entire start-up course it is difficult to ensure that voltage is adjusted with the optimal synchronisation of revolving speed.
Further, since the uncertainty of load, motor can often occur instantaneous or short in starting and normal steady state work When overcurrent impact, conventional overload protection method be when armature supply be more than it is a certain in advance as defined in fixed threshold when just at once into Row parking brake.However under normal conditions when there is moment overload, although dash current is larger due to the duration is shorter Though should not carry out stoppage protection or overload impact electric current do not reach given threshold because the duration is longer should Protection in time is carried out to shut down.As it can be seen that motor certainly will be will cause because frequently protecting for above-mentioned contradiction routine fixed threshold safeguard measure Shield acts and reduces the robustness of dragging system or burn motor because protecting not in time.
Summary of the invention
Goal of the invention:
The present invention is permanent torque starting and the overload intelligent protection device of a kind of direct current generator, and its object is to realize electric power With prestissimo clean boot motor and when motor wink occurs because of load disturbance in steady state operation in dragging process Between scientific and reasonable protection is carried out to it when overloading, thus under the premise of guaranteeing motor security application, the work of raising motor as far as possible Make the robustness of efficiency, performance and electric drive system.
Technical solution:
A kind of permanent torque starting of direct current generator and overload intelligent protection device, comprising:
Current closed-loop adjusts unit: including current sampling resistor Rs, D/A converter, linear optical isolation amplifier, low-pass filtering Device, voltage follower, phase inverter and pi regulator;
Pulse-width regulated unit: including saw-toothed wave generator, negative bias voltage, PWM wave generator, switching value light every circuit and Power MOS pipe;
Control unit includes DSP, motor overload alarm, motor operation/stopping detection circuit and DC-DC power module.
Preferably: the current sampling resistor RsValue is 10m Ω.
Preferably: the pi regulator is according to voltage U corresponding with given value of current amountigWith obtain from sample resistance with The corresponding voltage U of feedback currentifCarry out proportional plus integral control, output voltage UPAs the control voltage of PWM generator, change Its value is to adjust the duty ratio of PWM wave.
Preferably: by linear light isolated amplifier by current sampling resistor RsIt is carried out with subsequent weak signal controlled stage element Isolation.
Preferably: the low-pass filtered device of current feedback signal after the isolation carries out high-frequency noise inhibition and passes through voltage Follower buffering, the A/D converter being then separately dispensed into inside pi regulator and DSP, the former electric current as pi regulator Value of feedback input, the latter are then used for DSP and carry out real-time current detection and instantaneous overload protection.
Preferably: the digital quantity of the D/A converter inside the saw-toothed wave generator periodically-varied DSP;Since D/A becomes The output of parallel operation is the sawtooth wave of single positive polarity, passes through negative bias voltage UBIt carries out level to it and moves down to be converted to positive-negative polarity Waveform;PWM generator is in input terminal bipolarity sawtooth wave and control signal UpCollective effect under generate duty ratio can be online The pulse width modulating signal U of adjustingL;ULThe grid of power MOS pipe are acted on after switching value light-coupled isolation is amplified and is driven Pole carries out on-off control to it.
Preferably: the DSP has been internally integrated A/D, D/A, FLASH and I/O resource.
A kind of permanent torque starting of direct current generator and overload intelligent protection method, this method pass through motor working current closed loop Detection, pi regulator, PWM voltage control technology and current squaring decay algorithm realize that the permanent torque of direct current generator starts control With overload intelligent protection.
Preferably: DSP by I/O port detect motor open/guard's valve SW be closed after start sawtooth wave Interruption;Then Using starting current value preset in program as giving constant current Ig, and correspondence is converted to by the D/A converter inside DSP Voltage Uig, UigVoltage U corresponding with feedback currentifIt is inputted respectively as the specified rate of pi regulator and feedback quantity;PI is adjusted The output voltage U of devicepDetermine PWM generator output voltage ULDuty ratio, ULBy control MOS power switch on-off when Between realize motor average voltage and armature supply adjusting, and then achieve the purpose that permanent torque start.
Preferably: after DSP detects the starting time, program will give constant current IgBy original given starting current Igs It is reset to given operating current Igr, IgrSlightly larger than Rated motor operating current IN, so as to make motor in steady-state operation not It is influenced by load fluctuation within a narrow range;When motor operates normally, because of UigGreater than Uif, the output of pi regulator is in saturation always State, the duty ratio of PWM wave are 100%, and metal-oxide-semiconductor is completely open-minded, and motor loads full width voltage;When motor instantaneous overload, DSP meeting Detect that feedback current is greater than to constant current, program will give constant current I immediately at this timegGiven peak point current IgpIt is set as specified 5 times of current value, and make IgVariation, to realize the dynamic adjustment of current overload threshold value, to reach motor overload intelligent protection Purpose;Using micro process and pi regulator, without in the case where changing any hardware, only need to by modification software parameter and Given value of current value can arbitrarily set the duration of dash current and overloading threshold in starting current value and protection algorism.
Advantage and effect:
The present invention due to using the technology described above, has the advantage that (1) control system while having permanent torque starting With instantaneous overload intelligent protection dual function.(2) real by pulse duration modulation method, closed loop current detection technique and pi regulator The permanent torque starting of direct current generator is showed.Compared with string resistance mode, the starting time shortens one times, effectively increases motor and answers With the middle working efficiency for needing frequently to open;Permanent torque means permanent acceleration, entire to start compared with other change torque Starting mode Process has optimal stationarity.(3) by pi regulator and current closed-loop technology, decay in conjunction with overload impact current squaring and protect Shield algorithm realizes the intelligent protection of motor instantaneous overload.This method combines dash current value and certain a period of time at each moment Between section △ t dash current energy integral, using current squaring decay algorithm as Protection criteria, before guaranteeing motor safety Put, effectively overcome often occur because protect it is improper caused by malfunction problem, scientifically and rationally solve motor peace Contradiction between full guard and dragging system robustness.(4) micro process and pi regulator are used, without changing any hardware In the case of, only can need to arbitrarily it be set in starting current value and protection algorism by modification software parameter and given value of current value The duration of dash current and overloading threshold overcome and need to pass through change complex hardware according to different operating conditions in existing method The matched defect of parameter is carried out, to make control system that there is stronger versatility.(5) use common optical coupler to for containing friendship The hybrid analog-digital simulation signal of direct current realizes the optical isolation of control side and power side, and the industrial reliability for meeting control system is wanted It asks.
Detailed description of the invention:
Fig. 1 is the permanent torque starting and overload intelligent protection control system circuit block diagram that the present invention designs;
Fig. 2 is double optocoupler analog signal isolating circuits that the present invention uses;
Fig. 3 is the starting of permanent torque involved in the method for the present invention and overload intelligent protection signal waveform;
Fig. 4 is the pi regulator circuit designed in the method for the present invention;
Fig. 5 is the control circuit for pulse-width modulation that the method for the present invention uses;
Fig. 6 is the pulse-width modulation waveform figure in the method for the present invention;
Fig. 7 is permanent torque starting and the mechanical Property comparison of string resistance starting in the method for the present invention;
Fig. 8 is that the torque of permanent torque start-up course and revolving speed change over time rule in the present invention;
Fig. 9 is to control program flow diagram in the method for the present invention.
Specific embodiment:
Technical solution of the present invention and System Working Principle are specifically addressed with reference to the accompanying drawing.
On the basis of summarizing existing electric motor starting method and overcurrent protection measure, the invention proposes a kind of direct current separate excitations Or magneto permanent torque starts and overload intelligent protection method, and devises corresponding control device accordingly.The first purpose is In order to effectively solve electric motor starting current limited and detent torque maximize between contradiction, so as to armature allow by electricity The prestissimo starting of motor is realized under the premise of stream;The second purpose is to rationally solve to work as overload in motor stabilizing operational process Dash current energy should carry out making it automatic extensive when safeguard protection and smaller overload impact current energy again when larger in time The contradiction to run well again, sufficiently to improve the robustness of dragging system under the premise of guaranteeing motor reliability service.
A kind of starting of direct current generator permanent torque is with overload intelligent protection control system hardware configuration as shown in Figure 1, it is main Unit, pwm unit and control unit three parts are adjusted including current closed-loop.
Wherein, current closed-loop adjusts unit, for passing through current closed-loop real-time detection armature supply;Including current sampling electricity Hinder Rs, D/A converter, linear optical isolation amplification, low-pass filter, voltage follower, phase inverter and pi regulator.In order to as far as possible Reduce current sampling resistor RsInfluence to armature circuit, while considering that it will will have one by biggish electric current and current detecting Fixed sensitivity will select the power resistor of 10m Ω or so.D/A converter be used for control unit is set starting current value, Working current value and the dynamic current protection threshold transition described by overload function are corresponding analog voltage and adjust as PI The specified rate of device.Pi regulator is according to voltage U corresponding with given value of current amountigWith obtained from sample resistance and actual current It is worth corresponding voltage UifCarry out proportional plus integral control, output voltage UPAs the control voltage of PWM generator, changing its value can To adjust the duty ratio of PWM wave.Due to RSDirectly connect with high current high power motor, for improve control system reliability, It is isolated with subsequent weak signal controlled stage element by linear light isolated amplifier.Current feedback signal warp after isolation Low-pass filter carries out high-frequency noise inhibition and is buffered by voltage follower, is then separately dispensed into pi regulator and DSP The A/D converter in portion, the former inputs as the current feedback values of pi regulator, and the latter is then used for DSP and carries out real-time current detection It is protected with motor instantaneous overload.
Wherein, pulse-width regulated unit, for adjusting motor average voltage and electric current;Including saw-toothed wave generator, negative bias Voltage, PWM wave generator, switching value light are every circuit and power MOS pipe.Saw-toothed wave generator passes through inside periodically-varied DSP D/A converter numerical value obtain.Due to the sawtooth wave that the output of D/A converter is single positive polarity, pass through negative bias voltage UBLevel is carried out to it moves down the waveform for being converted to positive-negative polarity.PWM generator is in the bipolarity sawtooth wave of input terminal and control Signal UpCollective effect under generate duty ratio can on-line control pulse width modulating signal UL。ULBy switching value optocoupler every From the grid for acting on power MOS pipe after amplification and driving, on-off control is carried out to it, adjusts motor average voltage to reach With the purpose of electric current.
Using pi regulator and pulse duration modulation method dynamic adjustment average voltage, to make motor under the conditions of allowing carrying Maximum detent torque is obtained, and intelligent protection is implemented to it by current squaring attenuation law in instantaneous overload.
Wherein, control unit, the starting current value for that will set and the overload dynamic current limiting threshold by overload function description Value is converted to analog voltage, and real-time detection motor opens/stops state and current working current and is by timer interrupt mode PWM generator provides sawtooth wave;Including DSP (digital signal processor), motor overload alarm, motor operation/stopping detection electricity Road and DC-DC power module.The preferred model TMS320F2812 or TMS320F2407 of the DSP, has been internally integrated A/ D, D/A, FLASH and enough I/O resources.Mainly there are three functions for control unit: one is passing through its internal D/A converter It is analog voltage by the starting current value of software set and by the overload dynamic current limiting threshold transition of overload function description, as PI The specified rate of adjuster;The second is opening/stopping state and current work by its internal I/O and A/D module real-time detection motor Make electric current, the criterion of size of current and overload-alarm is given as program;The third is being PWM generator by timer interrupt mode Sawtooth wave is provided.DC-DC includes two-way ± 12V, 3.3V power supply exports all the way.Wherein all the way ± 12V to the related device in power side Power supply, including linear optical isolation amplifier and switching value light every the power side of amplifier.Another way ± 12V is used as to non-power side Related device power supply, occurs including alarm, the phase inverter connecting with D/A, filter, voltage follower, pi regulator, PWM The control side of device, linear optical isolation amplifier and the amount of opening the light amplifier.3.3V output is DSP and opens/guard's valve power supply.
To meet industrial Control for Dependability requirement, the weak signal side of control system and power strong signal side need to be carried out every From.Because armature supply sampled signal is analog signal and contains DC component, can not be using the number of transformer isolation or routine Word light-coupled isolation, the present invention realize that the principle of signal isolation is as follows using double optocouplers as shown in Figure 2: setting G1And G2Electric current pass Defeated coefficient is respectively α1And α2, then have
I21I1, I32I1 (1)
According to integrated transporting discharging knowledge, the voltage gain of circuit can be determined by following formula
(1) formula is substituted into (2) formula, is obtained
Due to G1、G2It is the optocoupler of same performance, the current transmission coefficient α of the two1And α2It is equal, therefore the voltage gain of circuit For AU=R3/R2, realize the analog signal isolation of analog signal.Amplifier A in Fig. 22For voltage follower, for improve every Fan-out capability from amplifier.Capacitor C is used to eliminate the self-oscillation of circuit.
Fig. 3 gives permanent torque starting and instantaneous overload signal waveform.Core of the invention technology first is that passing through motor The detection of operating current closed loop, PI adjusting method and PWM voltage control technology realize that the permanent torque of direct current generator starts control.Specifically Implementation method is as follows: firstly, DSP by I/O port detect motor open/guard's valve SW be closed after start sawtooth wave Interruption, be The generation of PWM wave provides necessary condition.Then using starting current value preset in program as giving constant current Ig, and pass through D/A converter inside DSP is converted to corresponding voltage Uig, UigVoltage U corresponding with feedback currentifIt is adjusted respectively as PI The specified rate and feedback quantity of device input.The output voltage U of pi regulatorpDetermine PWM generator output voltage ULDuty ratio, To realize electric moter voltage control by the make-and-break time of control MOS power switch.Since current of electric and voltage are positively correlated, because This can reach the purpose of current regulation by adjusting voltage.Specific adjustment process is as follows: before powering on, pi regulator output voltage It is zero, metal-oxide-semiconductor shutdown, armature does not have electric current to pass through;At the beginning of system detection to power on signal, due to Current feedback voltage at this time UigIt is 0, Uif>Uig, therefore the U under the control of pi regulatorpIt is gradually increased, the duty ratio of PWM wave and motor average voltage is caused to increase Add, so armature supply increase, until armature supply increase to given value after PI regulating system reach balance, at this time motor into Enter permanent torque startup stage.As revolving speed increases, armature induction electromotive force is also increase accordingly, when revolving speed increases to turnover revolving speed nc When, the duty ratio of PWM wave reaches 100%, and motor load at this time reaches full width voltage rating, and armature supply is protected always during this period It holds as steady state value.With continuing growing for revolving speed, armature supply is begun to decline, and feedback current will also reduce therewith, at this time because giving Constant current perseverance is greater than feedback current, and pi regulator enters saturation output state, and PWM wave duty ratio is maintained at 100%, and metal-oxide-semiconductor will Keep saturation conduction state.Until current of electric is decreased to rated operational current IN, start-up course terminates, into normal fortune Row state.It should be noted that being finished in order to ensure motor sufficiently starts, the given starting time t set by DSP timergs It should be slightly bigger than practical starting time ts
Core of the invention technology second is that passing through current closed-loop detection, pi regulator, PWM voltage control technology and overcurrent Protection algorism implements intelligent protection for the instantaneous overload impact occurred during direct current generator steady operation.Below with reference to Fig. 3 Illustrate its concrete operating principle and method.When the timer of DSP reaches given starting time tgsAfterwards, program will give constant current Ig Given operating current I is reset to by original starting current valuegr, IgrIt should be slightly bigger than Rated motor operating current IN, purpose It is to influence motor by load fluctuation within a narrow range in steady-state operation.Under the specified operating status that motor does not overload, Because of UigGreater than Uif, the output of pi regulator is in a saturated state always, and the duty ratio of PWM wave is 100%, and metal-oxide-semiconductor is opened completely Logical, motor loads full width voltage.When leading to motor instantaneous overload for some reason, such as t in Fig. 30And t3Moment, DSP can be examined It measures feedback current to be greater than to constant current, program will give constant current I immediately at this timegGiven peak point current IgpIt is set as specified electricity 5 times of flow valuve, and make IgBy the time square law decaying as described in following formula:
Ig=Igp-kt2 (4)
The function is known as overload protection function, wherein k is constant, is overload function attenuation coefficient, value determines given The speed of current function decaying.K is bigger, and given current value is decayed faster, i.e. IgFrom IgpDecay to IgrTime experienced gets over It is long.After motor causes instantaneous overload, pi regulator will comply with overload function to constant current and be gradually reduced, and during which motor overload has Two kinds of situations, respectively such as t in Fig. 30-t1And t3-t4Shown in period.The former is not above the electric current during overload continues always Constant current is given by overload function setting, through spontaneous recovery after a period of time to normal current value, system does not take overload shutdown Protection act;The latter's electric current during overload continues at a time is more than by overload function constraint to constant current, then system Protection act is taken immediately, i.e., will give constant current I by programgIt is set as 0, to pass through pi regulator for the duty of PWM wave Than being reduced to 0, current of electric is cut off eventually by shutdown metal-oxide-semiconductor, while carrying out overload-alarm.By taking above-mentioned overload intelligence Safeguard measure had both been avoided and had accidentally been protected caused by being disturbed as transient impact, and in turn avoided causing because duration of overload is longer Motor damage, thus effectively increase the robustness and reliability of dragging system.
Acceleration of starting, steady-state operation and overload protection braking in the present invention in relation to motor are finally adjusted by PI The duty ratio of the output voltage control PWM wave of device, and then change the make-and-break time realization of metal-oxide-semiconductor.Fig. 4 show pi regulator Circuit constitute, output voltage is represented by
The output voltage U of adjusterPPWM generator is acted on for controlling the duty ratio of PWM waveform, PWM wave is by opening Pass amount light controls the conducting degree of metal-oxide-semiconductor after amplification, to realize that voltage adjusts purpose.By formula (5) it is found that working as feedback current Less than to constant current, i.e. Uif<UigWhen, due to integrating effect, UPIt greater than 0 and is continuously increased, leads to PWM wave duty ratio and motor electricity Pressure increase, on the contrary it is then cause PWM wave duty ratio and electric moter voltage reduction.If feedback current is always less than to constant current, PWM wave Duty ratio is 100%, and metal-oxide-semiconductor is fully on, and motor obtains full width voltage;If being zero to constant current, PWM wave duty ratio is Zero, metal-oxide-semiconductor cut-off is equivalent to disconnection electric moter voltage.It can be seen that without doing any change to hardware, not by software setting Same given current value can achieve the purpose of any adjustment electric moter voltage, final to realize permanent torque starting, steady-state operation and mistake Carry the purpose of stoppage protection.
The control circuit for pulse-width modulation that the present invention uses is as shown in figure 5, its core is voltage comparator.The same phase of comparator A Three signals of end input: signal U is wherein controlledPFrom the output of pi regulator, size and polarity determine PWM output letter Number ULDuty ratio;Sawtooth signal USThe INVENTIONPeriodic digital amount given by program provides after D/A is converted, and frequency is PWM letter Number switch modulation frequency: negative bias voltage UBAbsolute value be equal to USCrest voltage USP;.Fig. 5 in-phase end input current i by Following formula acquires
The comparator output level U when i zero passageDIt jumps.Work as UP<-(UB+US) when UDIt is negative, UL=0;Work as UP>-(UB+ US) when UDIt is positive, ULFor high level.
Fig. 6 gives pulse-width modulation waveform, it is seen then that as the output U of pi regulatorPWhen change, pwm signal ULDuty ratio (the ratio between high level time τ and cycle T) also follows variation.Due to ULDriving switch metal-oxide-semiconductor is used for after amplifying by linear optical isolation Grid g, on-off control is carried out to it, so achieve the purpose that motor average voltage size control.
Fig. 7 is that permanent torque of the present invention starts compared with the mechanical property of traditional string resistance stepped starting.Fig. 8 is this hair The bright torque of permanent torque start-up course and revolving speed versus time curve.Wherein constant current starting characteristic such as Fig. 7 solid line institute Show, start-up course such as solid arrow label direction.After powering on, under the control of pi regulator and current closed-loop feedback system, motor With constant current ISStarting (or torque TS), revolving speed linearly rises to the corresponding revolving speed n of B point along AB line segment from 0CIt (referred to as transfers Speed), the corresponding starting time is t1, then electromagnetic torque is progressively smaller until on revolving speed along intrinsic mechanical characteristic BC Rise to rated speed nN.At AB sections of permanent torque, revolving speed and torque meet following relationships:
Wherein, G is the weight (N) of rotating part;D is inertia diameter (m);TLFor load torque (Nm).To permanent torque The load above formula left side is definite value, therefore motor rotation acceleration dn/dt is definite value, and during which t is pressed on linear rule revolving speed n at any time It rises, such as the O-n in Fig. 8CShown in line segment, the revolving speed relationship of changing with time can be described by following equation:
When have passed through t1After time, motor rises to turnover revolving speed nC, corresponding physical significance is that PWM wave accounts at this time For sky than having reached 100%, metal-oxide-semiconductor has been in complete opening state, i.e. supply voltage has expired width and is loaded into armature both ends.nC Meet following relationship
Wherein, UsFor Rated motor voltage;RaFor armature resistance;CeFor back EMF constant;For every pole magnetic flux.Consider It arrivesWithINT can be acquired by formula (8) and (9) for rated current or load current1Are as follows:
WhereinReferred to as electromechanical time constant.As it can be seen that permanent torque starts time t1With Rated motor voltage USRaising and increase, with starting current ISIncrease and shorten.
Terminate from permanent torque starting to specified period △ t (the i.e. t carved when operation starts2-t1) it is known as transient process, root According to electric machine theory, revolving speed changes with time rule during this period are as follows:
By formula (11) as it can be seen that theoretically, only as t=∞, n can be only achieved nN, but actually work as t=3TtMWhen, n The 95% of rated speed is just had reached, therefore can use △ t=3TtM, system substantially has reached rated speed.Permanent torque starts method The start up time be
To give the mechanical property of two-stage string resistance switching starting using dotted line and hollow arrow in Fig. 7 convenient for comparing. At the beginning of powering on, armature circuit is by Ra、RΩ1And RΩ2Three resistance are in series, and (first order all-in resistance is denoted as R1), starting current/turn Square is gradually reduced along artificial mechanical property AD sections and revolving speed is gradually increasing, until being reduced to the switching electric current I of D pointCWhen short circuit RΩ2 (second level all-in resistance is denoted as R2), at this time because revolving speed is constant, operating point is switched to E point starting current and increases to I againSAnd along EF sections Operation, when reaching F point by RΩ1With RΩ2All short circuits, operating point is switched to B point and moves along intrinsic mechanical characteristic at this time It is dynamic, until the C point start-up course that armature supply is gradually decrease to rated value terminates, into steady operational status, when start up Between the sum of three periods corresponding to AD, EF and BC constitute, i.e. tAD、tEFAnd tBC, it can be found out by following formula:
Wherein Above three electromechanical time constant to be normalized, is obtained convenient for comparing
Above-mentioned string resistance two-stage starting method can be generalized to multistage.By formula (12) and (13) as it can be seen that permanent torque method and electricity The functional relation do not fixed of starting time of resistance switching method, for the direct current generator below by model Z -290, to two The starting time of person carries out quantitative comparison.The nameplate data of the motor are as follows: voltage rating UN=440V, rated operational current IN= 76A, armature winding resistance Ra=0.377 Ω.Choose IS=2IN=152A, (β is defined as I for starting current ratio β=1.664S/IC)。 The relevant parameter that the string resistance level Four starting being calculated according to above-mentioned formula and permanent torque start is as shown in table 1, the results showed that permanent The torque starting time shorten to the 55% of string resistance stepped starting, and starting speed approximation is doubled.
1. permanent torque of table starts compared with string resistance level Four start-up parameter
Fig. 9 is to control program flow diagram in the present invention, is divided into main program and interrupt service routine two parts.Wherein main program Execute as follows: (1) DSP register initializes, and given starting current I is arrangedgs, given peak point current Igp, given work Electric current Igr, given starting time tgsAnd overload five parameters of attenuation coefficient k;(2) motor start-up procedure program: when detecting electricity Pi regulator is set as starting current (I to constant current after pressing by machine start buttong=Igs), while opening the timing of starting time Timer occurs for device, sawtooth wave and overload function controls timer.Motor starts by given electricity under pi regulator control at this time Flow valuve carries out permanent torque starting;(3) motor works normally program: main program starts the time by starting time timer detection, It is repeatedly detected if starting duration does not arrive, pi regulator is otherwise set as motor working current (I to constant currentg=Igr), Since operating current is slightly larger than rated current of motor, therefore pi regulator is in saturation output state when motor normal work, thus Keep metal-oxide-semiconductor fully on, the duty ratio of PWM wave is 100% at this time, and motor obtains full width supply voltage.Program is followed during this period Ring detects feedback current and by it compared with to constant current, if the former is less than the latter, illustrates that motor does not overload, continues cycling through inspection It surveys, otherwise illustrates that motor generates overload;(4) motor instantaneous overload processing routine: after detecting motor overload, immediately by given electricity Stream is set as moment maximum allowable peak point current (Ig=Igp), and be allowed under the control of overload function timer by Ig=Igp- kt2Square law decaying.If feedback current I during this periodf>Ig, illustrate that overload degree is serious, then by the way that constant current I will be giveng It is set as 0 closing metal-oxide-semiconductor and protects and alarm to realize motor overload, otherwise illustrate that overload degree is controlled in permissible range It is interior, then continue overload detection at this time, until IgIt decays to and is less than or equal to operating current Igr, by IgIt is re-set as Igr, Subsequently into the new round overload detection period.
Interrupt service routine (ISR) is made of four parts: (1) motor electrifying startup time timing;(2) sawtooth wave one it is complete Timing complete cycle;(3) D/A transducer data updates timing in sawtooth wave a cycle;(4) time used in overload function joins Number t timing.

Claims (10)

1. a kind of permanent torque starting of direct current generator and overload intelligent protection device, it is characterised in that:
Include:
Current closed-loop adjusts unit: including current sampling resistor Rs, D/A converter, linear optical isolation amplifier, low-pass filter, electricity Press follower, phase inverter and pi regulator;
Pulse-width regulated unit: including saw-toothed wave generator, negative bias voltage, PWM wave generator, switching value light every circuit and power Metal-oxide-semiconductor;
Control unit includes DSP, motor overload alarm, motor operation/stopping detection circuit and DC-DC power module.
2. the permanent torque starting of direct current generator and overload intelligent protection device according to claim 1, it is characterised in that: described Current sampling resistor RsValue is 10m Ω.
3. the permanent torque starting of direct current generator and overload intelligent protection device according to claim 1, it is characterised in that: described Pi regulator is according to voltage U corresponding with given value of current amountigThe voltage corresponding with feedback current with what is obtained from sample resistance UifCarry out proportional plus integral control, output voltage UPAs the control voltage of PWM generator, change its value to adjust PWM wave Duty ratio.
4. wanting the permanent torque of 1 direct current generator to start and overload intelligent protection device according to right, it is characterised in that: pass through line Property optical isolation amplifier is by current sampling resistor RsIt is isolated with subsequent weak signal controlled stage element.
5. the permanent torque starting of direct current generator and overload intelligent protection device according to claim 4, it is characterised in that: described The low-pass filtered device of current feedback signal after isolation carries out high-frequency noise inhibition and is buffered by voltage follower, then distinguishes The A/D converter being assigned to inside pi regulator and DSP, the former inputs as the current feedback values of pi regulator, and the latter then uses Real-time current detection is carried out in DSP to protect with instantaneous overload.
6. the permanent torque starting of direct current generator and overload intelligent protection device according to claim 1, it is characterised in that: described The digital quantity of D/A converter inside saw-toothed wave generator periodically-varied DSP;Due to D/A converter output be it is single just Polar sawtooth wave passes through negative bias voltage UBLevel is carried out to it moves down the waveform for being converted to positive-negative polarity;PWM generator exists The bipolarity sawtooth wave and U of input terminalpCollective effect under generate duty ratio can on-line control UL;ULBy switching value optocoupler every From the grid for acting on power MOS pipe after amplification and driving, on-off control is carried out to it.
7. the permanent torque starting of direct current generator and overload intelligent protection device according to claim 1, it is characterised in that: described DSP has been internally integrated A/D, D/A, FLASH and I/O resource.
8. a kind of permanent torque starting of direct current generator and overload intelligent protection method, it is characterised in that:
It is realized by the detection of motor working current closed loop, pi regulator, PWM voltage control technology and current squaring decay algorithm The permanent torque starting control and overload intelligent protection of direct current generator.
9. the permanent torque starting of direct current generator and overload intelligent protection method according to claim 8, it is characterised in that: DSP By I/O port detect motor open/guard's valve SW closure after start sawtooth wave Interruption;It then will be preset in program Starting current value is used as and gives constant current Ig, and corresponding voltage U is converted to by the D/A converter inside DSPig, UigWith feedback The corresponding voltage U of electric currentifSpecified rate and feedback quantity input respectively as pi regulator;The output voltage U of pi regulatorpIt determines PWM generator output voltage ULDuty ratio;ULMake-and-break time by controlling MOS power switch realizes motor average voltage With the adjusting of armature supply, and then achieve the purpose that permanent torque start.
10. the permanent torque starting of direct current generator and overload intelligent protection method according to claim 8, it is characterised in that: DSP After detecting the starting time, program will give constant current IgBy original given starting current IgsIt is reset to given work Electric current IgrValue, IgrSlightly larger than rated current of motor IN, to make motor in steady-state operation not by the shadow of load fluctuation within a narrow range It rings;When motor operates normally, because of UigGreater than Uif, the output of pi regulator is in a saturated state always, and the duty ratio of PWM wave is 100%, metal-oxide-semiconductor is completely open-minded, and motor loads full width voltage;When motor instantaneous overload, DSP can detect feedback current be greater than to Constant current, program will give constant current I immediately at this timegGiven peak point current Igp5 times of load current value are set as, and makes IgBecome Change, to realize the dynamic adjustment of current overload threshold value, to achieve the purpose that motor overload intelligent protection;Using micro process and PI Adjuster, without only can need to arbitrarily be set by modification software parameter and given value of current value in the case where changing any hardware Determine the duration of dash current and overloading threshold in starting current value and protection algorism.
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CN111211540A (en) * 2020-01-20 2020-05-29 菲仕绿能科技(宁波)有限公司 Active short circuit method for preventing torque impact
CN111900901A (en) * 2020-08-06 2020-11-06 珠海格力电器股份有限公司 Start control method and device for oil pump motor, automobile, medium and processor
CN112238755A (en) * 2019-07-17 2021-01-19 北京新能源汽车股份有限公司 Electric vehicle driving motor software overcurrent processing method and device and electric vehicle
CN112383251A (en) * 2020-11-27 2021-02-19 珠海格力电器股份有限公司 Motor starting control method and device, motor, storage medium and processor

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CN112238755A (en) * 2019-07-17 2021-01-19 北京新能源汽车股份有限公司 Electric vehicle driving motor software overcurrent processing method and device and electric vehicle
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