CN100488026C - AC motor frequency conversion controller torque ripple following circuit and its method - Google Patents
AC motor frequency conversion controller torque ripple following circuit and its method Download PDFInfo
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- CN100488026C CN100488026C CNB2005100753651A CN200510075365A CN100488026C CN 100488026 C CN100488026 C CN 100488026C CN B2005100753651 A CNB2005100753651 A CN B2005100753651A CN 200510075365 A CN200510075365 A CN 200510075365A CN 100488026 C CN100488026 C CN 100488026C
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Abstract
The invention relates to a method for realizing the torque fluctuation following of alternative-current motor, and relative circuit, used in single chip as the variable-frequency controller, wherein said circuit comprises an alternative-current motor current detecting circuit and a bus voltage detecting circuit; the current detecting circuit detects the driving current of alternative-current motor to realize the torque fluctuation following, which comprises a sampling circuit, a rectify filter circuit, an input circuit and a single chip; said bus voltage detecting circuit, via detecting the bus voltage, obtains the difference between the voltage of power supply and the rating, according to which, it adjusts the output voltage of driving power supply, to realize the output torque fluctuation following; said circuit comprises a sampling circuit, a rectify filter circuit, an input circuit and a single chip.
Description
Technical field
The present invention relates to alternating current motor AC frequency conversion controller torque ripple following circuit, especially relate to the single-chip microcomputer torque ripple following circuit of the alternating current motor AC frequency conversion controller that is control device, and the torque ripple following method that is used for this circuit.
Background technology
Along with the raising to domestic electric appliances energy-saving requirement and intelligent requirements, alternating frequency conversion technique has been widely used in household appliance technical field.The effect of alternating frequency conversion technique is to adjust in the AC frequency modulation mode rotating speed of alternating current motor, thereby satisfies different speed demand, plays simultaneously and avoids the alternating current motor energy to waste, and reaches the purpose of electrical energy saving.
Being extensive use of of alternating frequency conversion technique is the advantage decision by itself.This point can be illustrated from the principle of motor speed adjusting.
Motor can be divided into alternating current motor, DC motor.Alternating current motor (referring to AC asynchronous motor herein, both can be threephase asynchronous, also can be unidirectional asynchronous motor) is simple in structure, easy to maintenance, cheap, is widely used in various occasions.Compare with DC motor, its major defect is controlled bad.The speed regulation of alternating current motor, torque adjustment are all relatively more difficult.
Improve the control performance of alternating current motor, especially improve its speed adjusting performance, be the hot issue in Motor Control field always.Frequency control is exactly the speed regulating method of the extensive alternating current motor that adopts.
Below be the rotating speed formula of alternating current motor:
n＝60f(1-s)/p (1)
The rotating speed of n in the formula---asynchronous motor;
The frequency of f---asynchronous motor;
S---alternating current motor revolutional slip;
P---alternating current motor number of pole-pairs.
By formula (1) as can be known, rotation speed n is directly proportional with frequency f, as long as change the rotating speed that frequency f can change alternating current motor, and when changing in the scope of frequency f at 0～50Hz, the non-constant width of alternating current motor rotational speed regulation scope.Frequency control realizes speed regulation by changing alternating current motor driving power frequency.
Use maximum friendships-straight-friendship mode voltage type variable-frequency control device to form at present by rectifier, filtering system and inverter three parts.When its work, be direct current through the bridge rectifier rectification at first with alternating current, the direct voltage of pulsation is behind smothing filtering, under the regulation and control of microprocessor, direct current another mistake is become the alternating current of voltage and frequency adjustable with inverter, it as driving power, is outputed on the alternating current motor that needs speed governing.Because the rotating speed of alternating current motor is directly proportional with supply frequency, can change alternating current motor driving power output frequency arbitrarily by frequency-variable controller, thereby regulate the alternating current motor rotating speed arbitrarily, realizes level and smooth stepless speed regulation.
Fig. 1 illustrates under the prior art with the AC frequency conversion controller function block diagram of single-chip microcomputer as controlling element.
This AC frequency conversion controller is made up of current rectifying and wave filtering circuit, inverter circuit, inverter control circuit, power circuit, output driving frequency initialization circuit, communicating circuit.
Current rectifying and wave filtering circuit is general to adopt common bridge rectifier to add the capacitor filtering circuit bank, and main effect is that alternating current is transformed to direct current.
Inverter circuit is used for the direct current of input is converted to alternating voltage, drives alternating current motor.
Inverter control circuit is the core of whole frequency conversion plate, is made up of single-chip microcomputer, inverse changing driving circuit, communicating circuit, can also comprise the driving frequency initialization circuit.This circuit is responsible for according to command request, calculates to obtain drive signal, drives inverter output sinusoidal voltage, drives the alternating current motor running.
Wherein, single-chip microcomputer is used to provide and realizes driving the control command signal of handling as controlling element.Single-chip microcomputer calculates and obtains described control command signal according to the demand to alternating current motor rotating speed, torque.
Inverse changing driving circuit is the bridge that connects single-chip microcomputer and inverter circuit, its role is to accept the control command signal of single-chip microcomputer output, and exports drive pulse signal in view of the above to inverter circuit.
Communicating circuit is the circuit that carries out communication with host computer, accepts from upper instruction, and replys execution result.
The driving frequency initialization circuit is the circuit that is used for directly setting output frequency.This circuit can connect setting signal, and this setting signal can be determined output frequency according to outside incoming frequency.Can be by using different modular programs or the frequency conversion plate being set selection by the mode of communication.
Power circuit is the power supply circuits of whole frequency-variable controller.
Above-mentioned frequency-variable controller can be realized rotating speed, the torque control to alternating current motor, but also has some defectives.
A major defect is, above-mentioned is the frequency-variable controller of kernel control chip with the single-chip microcomputer, can't control the constancy of the output torque of alternating current motor, thereby influence is to the rotating speed control of alternating current motor, when alternating current motor output torque is excessive, might damage alternating current motor.
The reason that influences alternating current motor output torque mainly is mains fluctuations and load variations.
In actual the use, supply voltage often has than great fluctuation process, uses above-mentioned prior art, and the fluctuation of supply voltage can cause the voltage fluctuation of alternating current motor driving power, thereby makes the torque of alternating current motor output can't keep constant.
In addition, household electrical appliance such as washing machine usually have bigger load variations in actual use.Load increases, if the alternating current motor rotating speed is constant, then alternating current motor output torque meeting increases.At this moment, the alternating current motor electric current also can increase, and when the increase of alternating current motor electric current surpassed certain degree, the alternating current motor coil can suffer damage owing to electric current is excessive, even burns alternating current motor.
Single-chip microcomputer is the AC frequency conversion controller of kernel control chip, can't in time know the variation of supply voltage, and the load variations of alternating current motor, therefore can't take appropriate measures in good time, make the alternating current motor holding torque constant, avoid excessive alternating current motor electric current.
Summary of the invention
At above-mentioned defective, the technical problem that the present invention solves is: according to the characteristics of single-chip microcomputer, for above-mentioned with the single-chip microcomputer be control core the AC frequency conversion controller a kind of suitable torque ripple following circuit is provided, so that variation according to supply voltage and load, in time adjust driving power frequency and voltage, keep the constant output of alternating current motor torque.
Technical scheme provided by the invention is specifically: at influencing the constant reason of alternating current motor torque, in the AC frequency conversion controller, increase the circuit unit that detects alternating current motor drive current and busbar voltage, take corresponding measure according to testing result, realize torque ripple following control alternating current motor.
The testing circuit of described alternating current motor drive current comprises sample circuit, current rectifying and wave filtering circuit, input circuit, single-chip microcomputer.
The effect of described sample circuit is that sampling obtains sampling current from the alternating current motor drive current.
The effect of described current rectifying and wave filtering circuit is, takes out the part electric current and carry out rectifying and wave-filtering from described sampling current, makes it to become the voltage detection signal output that is fit to the input single-chip microcomputer.
The effect of described input circuit is to carry out level and smooth and filtering and output to the described voltage detection signal of described current rectifying and wave filtering circuit output.
Described single-chip microcomputer receives the output of described input circuit and the motor speed information that the motor speed feedback electric circuit inspection obtains; Output according to described input current, obtain the driving current value of alternating current motor, when the accumulated time that surpasses default alternating current motor current threshold when this current value surpasses default accumulated time threshold value, further judge whether motor speed is lower than default rotary speed threshold value, if, then single-chip microcomputer is exported corresponding instruction, reduces the output frequency and the output voltage of this motor driven power supply, to reduce the electric current by alternating current motor; If motor speed is normal, then adjust the duty ratio of this motor driven supply voltage, to reduce the alternating current motor driving voltage of this motor driven power supply output, make the alternating current motor drive current be reduced to normal level.
Preferably, the testing circuit of described alternating current motor drive current further comprises the anti-jamming circuit of the radio-frequency component in the filtering and sampling electric current; This anti-jamming circuit receives the sampling current of sample circuit output, exports this filtered sampling current to described current rectifying and wave filtering circuit.
Preferably, the torque ripple following circuit of described AC motor frequency conversion controller further comprises guaranteeing that described voltage detection signal is lower than the pressure limiting circuit of the ceiling value of single-chip microcomputer input; This pressure limiting circuit receives the output of described input circuit, after its pressure limiting, exports to the single-chip microcomputer input port.
Preferably, in the torque ripple following circuit of described AC motor frequency conversion controller, described current rectifying and wave filtering circuit comprises rectifier diode (D2), electrochemical capacitor (C3), resistance (R7).
The anode of rectifier diode (D2) connects described sampling current.
Electrochemical capacitor (C3) is in parallel with resistance (R7), wherein is parallel with the negative electrode that the anodal parallel connected end of electrochemical capacitor (C3) connects rectifier diode (D2), another parallel connected end ground connection.
Preferably, the torque ripple following circuit of described AC motor frequency conversion controller, described sample circuit are current sensor.
The present invention is provided for the method for the torque ripple following of foregoing circuit simultaneously, comprises step:
61) detect the alternating current motor electric current;
62) judge whether described alternating current motor current value is higher than default alternating current motor current threshold; If then enter step 63); If not, then enter step 66);
63) this alternating current motor current value of accumulative total is higher than the time of default alternating current motor current threshold;
64) if described alternating current motor current value is higher than the time accumulative total of default alternating current motor current threshold when surpassing predetermined value, read the alternating current motor rotary speed information;
When 65) being lower than rotary speed threshold value, then adjust the output frequency and the voltage of alternating current motor driving power, to reduce electric current by alternating current motor as if the alternating current motor rotating speed; If the alternating current motor rotating speed is normal, then adjust the duty ratio of alternating current motor driving power voltage, to reduce the alternating current motor driving voltage of this alternating current motor driving power output;
66) zero clearing alternating current motor current value is higher than the time accumulated value of default alternating current motor current threshold.
With respect to prior art, the invention has the beneficial effects as follows:
At first, the present invention provides a kind of suitable torque ripple following circuit for being the AC frequency conversion controller of control device with the single-chip microcomputer, has solved torque ripple following problem in such cases.
Secondly, utilize the AC frequency conversion controller of torque ripple following provided by the invention, can suitably adjust the driving power output frequency and the voltage of control alternating current motor according to the alternating current motor load variations, change the rotating speed of alternating current motor, it is constant to keep the alternating current motor torque.Above-mentioned adjustment can avoid the excessive electric current that causes of alternating current motor output torque sharply to increase, and makes alternating current motor avoid infringement.
Description of drawings
Fig. 1 is a prior art motor AC frequency conversion controller block diagram;
Fig. 2 is the motor AC frequency conversion controller block diagram of first embodiment of the invention;
Fig. 3 is the velocity feedback circuits circuit diagram of first embodiment of the invention;
Fig. 4 is the alternating current motor drive current testing circuit of first embodiment of the invention;
Fig. 5 is the circuit diagram of the busbar voltage testing circuit of first embodiment of the invention;
Fig. 6 is the flow chart of method of the torque ripple following of first embodiment of the invention;
Fig. 7 is the flow chart of method of the torque ripple following of second embodiment of the invention;
Fig. 8 is the flow chart of method of the torque ripple following of third embodiment of the invention.
Embodiment
With reference to the accompanying drawings, embodiments of the present invention are described.
At first need to illustrate the relation of alternating current motor torque and alternating current motor electric current.
The relation of alternating current motor torque and alternating current motor electric current can be formulated as: T=C
TΦ
mI
2' cos φ.Wherein, C
TBe the alternating current motor parameter, in a single day alternating current motor is made, and then it no longer changes.Φ
mBe the alternating current motor main flux, cos φ is a power factor (PF), I
2' be the alternating current motor electric current.
From this publicity as can be seen, alternating current motor output torque is directly proportional with the electric current of alternating current motor, keeps air-gap flux Φ
mUnder the constant situation, it is constant that control alternating current motor current constant is controlled the alternating current motor torque exactly.And maintenance air-gap flux Φ
mConstant, only need to guarantee that the ratio of driving power voltage and frequency is that a constant gets final product.
Below technical scheme provided by the invention, it is constant all to obtain torque with the method for control alternating current motor current constant.Simultaneously, keeping the ratio of driving power voltage and frequency is that a constant is to keep air-gap flux Φ
mConstant.
Fig. 2 is the functional block diagram of frequency-variable controller with torque ripple following circuit of first embodiment of the invention.As can be seen compared with prior art, this frequency-variable controller has motor speed feedback circuit, motor drive current testing circuit and busbar voltage testing circuit, and foregoing circuit has constituted the alternating current motor torque ripple following circuit of first embodiment of the invention jointly.
Fig. 3 is the circuit diagram of described velocity feedback circuits.The effect of velocity feedback circuits is to provide the alternating current motor rotary speed information to single-chip microcomputer, makes single-chip microcomputer can judge whether the alternating current motor rotating speed is low excessively.Its operation principle is: according to detected umber of pulse in the unit interval, calculate the rotating speed of alternating current motor.About the method for this velocity feedback circuits and speed feedback thereof, separate case is applied for a patent, and number of patent application is: 200510075294.5.Element numbers in this circuit diagram and act on explanation is all arranged in this patent application document.No longer repeat at this.For the purpose of the present invention, it can provide the alternating current motor rotary speed information to get final product.
Fig. 4 is an alternating current motor drive current testing circuit.The effect of this circuit is a sampling current from the alternating current motor drive current, behind rectifying and wave-filtering, be input to the analog-to-digital conversion port of described single-chip microcomputer with the voltage that is fit to, i.e. the Chip Microcomputer A mouth of Fig. 4, single-chip microcomputer obtains the alternating current motor driving current value according to this voltage.
This circuit comprises sample circuit, anti-jamming circuit, current rectifying and wave filtering circuit, input circuit, pressure limiting circuit.
The effect of described sample circuit is the suitable sampling current of sampling from the alternating current motor drive current.This circuit comprises current sensor M.This current sensor M is from the phase line sampling current Iv and the output of alternating current motor driving power.
The main effect of described anti-jamming circuit is the radio-frequency component in the elimination sampling current, comprises resistance R 6, capacitor C 1.Described resistance R 6 is connected between sampling current Iv and the ground, its role is to avoid this electric current to be in vacant state.Capacitor C 1 is connected between sampling current and the ground, and the interchange bypass on flow direction ground is provided for the radio-frequency component of this sampling current Iv.
The effect of described current rectifying and wave filtering circuit is, takes out electric current from sampling current Iv and carries out rectifying and wave-filtering, becomes the direct current signal that is fit to the input single-chip microcomputer.
This circuit comprises: rectifier diode D2, electrochemical capacitor C3, resistance R 7.The anode of rectifier diode D2 connects sampling current Iv.Electrochemical capacitor C3 is in parallel with resistance R 7, and in its parallel connected end, the anodal end of electrochemical capacitor C3 connects the negative electrode of rectifier diode D2, another parallel end connection power supply ground GND.
The effect of rectifier diode D2 is the sampling current Iv that exchanges is carried out rectification.When sampling current Iv process rectifier diode D2, its positive half period can pass through rectifier diode D2, and its negative half-cycle can't pass through.Therefore, the cathode side of rectifier diode D2 becomes the pulsating current that has only positive half period.The effect of electrochemical capacitor C3 is, the electric current of the positive half period after the rectifier diode D2 rectification is carried out smothing filtering, makes it be transformed into the current value galvanic current from pulsating current and presses.The effect of resistance R 7 is for electrochemical capacitor C3 provides discharge loop, avoids electrochemical capacitor C3 both end voltage too high, further obtains level and smooth direct voltage Ui.
The effect of input circuit is the further elimination of the direct voltage radio-frequency component wherein for acquisition after the rectifying and wave-filtering, so that single-chip microcomputer obtains stable input voltage.
Described input circuit comprises capacitor C 2, inductance L 1.Described capacitor C 2 is in parallel with described resistance R 7.Described inductance L 1 one ends connect rectifier diode D2 negative electrode, and the other end connects the Chip Microcomputer A mouth.
The radio-frequency component that comprises among the direct voltage Ui of described capacitor C 2 for current rectifying and wave filtering circuit output provides bypass.The radio-frequency component of 1 couple of direct voltage Ui of described inductance L produces a high impedance, makes described radio-frequency component be easier to flow to ground by capacitor C 2.
The effect of described pressure limiting circuit is, guarantees that the described detection voltage U i that offers single-chip microcomputer is controlled in the ceiling value scope of single-chip microcomputer input.
Described pressure limiting circuit comprises voltage stabilizing didoe D3, and its negative electrode connects Chip Microcomputer A mouth, plus earth.
The effect of this pressure limiting circuit is, makes the voltage of input Chip Microcomputer A mouth be no more than the ceiling value of Chip Microcomputer A mouth, avoids the too high infringement single-chip microcomputer of this magnitude of voltage.
Fig. 5 is the circuit diagram of described busbar voltage testing circuit.This circuit comprises: sample circuit, pressure limiting circuit, input circuit.
The effect of described sample circuit is, sampling is fit to the voltage that the single-chip microcomputer input requires the higher DC bus-bar voltage Uv behind rectifying and wave-filtering, detects voltage U d as the bus of input Chip Microcomputer A mouth.This circuit comprises resistance R 8, R9, R10, R11.Above-mentioned resistance is series between the positive pole and power supply ground GND of dc bus successively.Wherein, resistance R 8 one ends directly are connected with the dc bus positive pole, and resistance R 11 1 ends directly are connected with power supply ground GND.Described detection voltage U d obtains from the sampling of resistance R 11 two ends.Resistance R 11 is called sample resistance.
The effect of described pressure limiting circuit is, guarantees that the described bus that offers single-chip microcomputer detects the ceiling value that voltage U d is no more than the Chip Microcomputer A mouth.
Because the power supply voltage fluctuation is bigger, and the mutation voltage that may exist, the bus that described sample circuit obtains detects the ceiling value of voltage that voltage U d may be higher than the Chip Microcomputer A mouth.This pressure limiting circuit can be avoided being higher than the Chip Microcomputer A mouthpiece and be subjected to the voltage of ability to enter single-chip microcomputer.
This pressure limiting circuit comprises voltage stabilizing didoe D4.This voltage stabilizing didoe D4 is in parallel with described sample resistance R11; Wherein, negative electrode connects the common ends of resistance R 11 and resistance R 10, and anode is connected with ground.The bus that this voltage stabilizing didoe obtains resistance R 11 two ends detects voltage U d and is limited in the scope that is no more than its voltage stabilizing value.The voltage stabilizing value of this voltage stabilizing didoe is not higher than the ceiling value of Chip Microcomputer A mouth, and this has just guaranteed that described bus detects the ceiling value that voltage U d is not higher than the single-chip microcomputer input port.
The effect of described input circuit is to carry out level and smooth and filtering to detecting voltage U d.Because described DC bus-bar voltage Uv is obtained by the electric main rectifying and wave-filtering.Therefore, wherein there are some high frequency compositions.Accordingly, the bus detection voltage U d that obtains from busbar voltage Uv comprises the high frequency composition equally.This filter circuit can detect bus the high frequency composition elimination among the voltage U d, makes single-chip microcomputer obtain accurate, stable magnitude of voltage, and the measured value that single-chip microcomputer obtains is also accurately stable more accordingly.
This input circuit comprises capacitor C 4 and inductance L 2.
Described capacitor C 4 is in parallel with resistance R 11, and its role is to provides the interchange bypass for the radio-frequency component of bus detection voltage U d.The radio-frequency component that bus detects voltage U d can flow to ground through this electric capacity, and the required low-frequency component of voltage detecting can't flow to ground by this electric capacity.
Described inductance L 2 is series at bus and detects between the positive pole and Chip Microcomputer A mouth of voltage U d.Its role is to bus is detected the bigger induction reactance of radio-frequency component setting of voltage U d, make interchange by-pass that above-mentioned radio-frequency component more provides from described capacitor C 4 to ground, it is then unaffected substantially that single-chip microcomputer carries out the required low-frequency component of voltage detecting.
See also Fig. 6, be the flow chart of the method for torque ripple following of the present invention.
According to the relation of aforementioned alternating current motor torque and electric current, the alternating current motor electric current is directly proportional with alternating current motor output torque, therefore, control alternating current motor electric current, make its maintenance constant, just make the alternating current motor torque constant, realize that promptly the fluctuation of alternating current motor torque is followed.This method is a controlling object with the alternating current motor electric current promptly, realizes that the fluctuation of alternating current motor torque is followed.
Step S601, initialization.
Step S602 detects busbar voltage, detects the alternating current motor electric current.
Detecting busbar voltage is that the bus detection voltage U d that utilizes described busbar voltage testing circuit to offer single-chip microcomputer finishes.The value of described detection voltage U d is directly proportional with busbar voltage, and this value enters single-chip microcomputer through the Chip Microcomputer A mouth, through analog-to-digital conversion, becomes a digital quantity.This digital quantity promptly can be used for representing bus voltage value.
Detecting the alternating current motor electric current is to utilize described alternating current motor current detection circuit to finish by the detection voltage U i that the Chip Microcomputer A mouth provides.Described detection voltage U i is directly proportional with the alternating current motor electric current, and the AD conversion through single-chip microcomputer inside becomes a digital quantity.This digital quantity can be used for representing the alternating current motor current value.
Step S603 calculates the poor of busbar voltage and rated value, adjusts output voltage according to difference.
Above-mentioned adjustment is specifically: the bus voltage value that step S602 is obtained and rated value relatively according to the difference that is obtained, are regulated the duty ratio of driving power voltage, so that alternating current motor obtains suitable voltage.
Step S604 judges whether the alternating current motor electric current is too high.
Single-chip microcomputer inside has set in advance the alternating current motor current threshold, when the alternating current motor current value is higher than this threshold value, illustrates that then the alternating current motor electric current is too high.
The alternating current motor current value that step S602 is obtained, with this threshold ratio, judge whether it is higher than this threshold value.In this way, then enter step S605; As not, then enter step S609.
Step S605, the cumulative time.
The alternating current motor electric current is too high, might be owing to alternating current motor is in normal reason such as start-up course, as long as the duration is shorter, and induced damage resistive alternating current motor not just.Therefore, the single-chip microcomputer palpus cumulative time is so that get rid of the temporary transient too high situation of the alternating current motor electric current that causes because of normal condition.Can establish this cumulative time value herein and be t.
Step S606 judges whether the too high time of continuous current exceed schedule time.
Single-chip microcomputer inside is provided with cumulative time threshold value Tn, when the too high time of alternating current motor current value surpasses this threshold value, illustrates that the alternating current motor working condition is unusual, should take appropriate measures.
Step S605 value t of described cumulative time and Tn are compared, judge whether t Tn.If then enter step S607; If not, then enter step S611.
Step S607 judges whether rotating speed is low excessively.
The overlong time that the alternating current motor electric current is too high has different situations, comprises that mainly overtension and rotating speed are low excessively.At different situations, should take different measures.
Be preset with rotary speed threshold value Vn in the single-chip microcomputer, when the alternating current motor rotating speed is lower than this threshold value, illustrate that rotating speed is low excessively.
Single-chip microcomputer compares alternating current motor rotating speed V and the Vn that velocity feedback circuits records.Judge whether alternating current motor rotating speed V is lower than Vn.If then enter step S608; If not, then tightly go into step S610.
Step S608 adjusts output frequency and voltage, to reduce the current protection alternating current motor.
According to above-mentioned a series of judgements, can know that the alternating current motor output current is too high to have surpassed the rational time, and be the alternating current motor rotating speed cross low due to.Therefore, can take appropriate measures in view of the above.
Concrete measure is output frequency and the voltage that reduces driving power, and the output frequency of driving power and the actual speed of voltage and alternating current motor are adapted.This measure can reduce the alternating current motor revolutional slip, reduces the current value by alternating current motor.
If, still can't reduce the alternating current motor electric current by adjusting, then abnormal conditions may appear, at this moment, should turn-off driving power, avoid alternating current motor to damage.
Step S609, the zero clearing time accumulated value.
Because the alternating current motor electric current is normal, should the too high time accumulated value of the described alternating current motor electric current of zero clearing, to avoid wrong accumulation result.
Step S610 adjusts output voltage.
According to aforementioned judgement, the too high overtime of alternating current motor electric current threshold value Tn as can be known, and the alternating current motor rotating speed is not low excessively may be due to the alternating current motor driving power overtension.Therefore, can reduce the driving voltage of output, make the alternating current motor drive current drop to normal level by adjusting the duty ratio of driving power voltage.
Step S611 carries out other work.
Single-chip microcomputer is carried out once above-mentioned flow process in each program cycle, and torque is controlled to alternating current motor.
The fluctuation follower method of above alternating current motor torque is with the complete alternating current motor control system of the common formation of described busbar voltage testing circuit, electric electromechanics current detection circuit and velocity feedback circuits.By determining to influence the constant reason of alternating current motor torque, take appropriate measures, finish the fluctuation of alternating current motor torque and follow.
Above-mentioned torque ripple following circuit and method, can be that 200510075294.5 disclosed speed feedback control circuit of patent application and alternating current motor method for controlling number of revolution thereof combine with the applicant's application number, constitute the alternating current motor control system that comprises torque ripple following, two feedback loops of speed feedback control.Such control system can have more good control performance.
Fig. 7 is the second embodiment of the invention flow chart.The AC frequency conversion controller of this embodiment only uses the busbar voltage testing circuit, does not comprise electric electromechanics current detection circuit, motor speed feedback circuit (relevant block diagram omits).Simultaneously, the method for the torque ripple following of first embodiment is made corresponding modify, concrete modification is seen flow chart.Its each step particular content is identical with the first embodiment counterpart, repeats no more.
Present embodiment is only followed control to the alternating current motor torque ripple that mains fluctuations cause, and does not detect motor current.
Fig. 8 is the third embodiment of the invention flow chart.This embodiment only uses alternating current motor current detection circuit and velocity feedback circuits, does not comprise busbar voltage testing circuit (relevant block diagram omits).Simultaneously, the method for the torque ripple following of first embodiment is made corresponding modify, concrete modification is seen flow chart.Its each step particular content is identical with the first embodiment counterpart, repeats no more.
Present embodiment is only followed control to the alternating current motor torque ripple that motor current causes unusually, and does not detect busbar voltage.
The above only is a preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (6)
1, a kind of torque ripple following circuit of AC motor frequency conversion controller, realize the control of alternating current motor torque ripple following by detection to the alternating current motor drive current, it is characterized by, comprising: sample circuit, current rectifying and wave filtering circuit, input circuit, single-chip microcomputer;
The effect of described sample circuit is that sampling obtains sampling current from the alternating current motor drive current;
The effect of described current rectifying and wave filtering circuit is, takes out the part electric current and carry out rectifying and wave-filtering from described sampling current, makes it to become the voltage detection signal output that is fit to the input single-chip microcomputer;
The effect of described input circuit is to carry out level and smooth and filtering and output to the described voltage detection signal of described current rectifying and wave filtering circuit output;
Described single-chip microcomputer receives the output of described input circuit and the motor speed information that the motor speed feedback electric circuit inspection obtains; Output according to described input circuit, obtain the driving current value of alternating current motor, when the accumulated time that surpasses default alternating current motor current threshold when this current value surpasses default accumulated time threshold value, further judge whether motor speed is lower than default rotary speed threshold value, if, then single-chip microcomputer is exported corresponding instruction, reduces the output frequency and the output voltage of this motor driven power supply, to reduce the electric current by alternating current motor; If motor speed is normal, then adjust the duty ratio of this motor driven supply voltage, to reduce the alternating current motor driving voltage of this motor driven power supply output, make the alternating current motor drive current be reduced to normal level.
2, the torque ripple following circuit of AC motor frequency conversion controller according to claim 1 is characterized by, and further comprises the anti-jamming circuit of the radio-frequency component in the filtering and sampling electric current; This anti-jamming circuit receives the sampling current of sample circuit output, exports this filtered sampling current to described current rectifying and wave filtering circuit.
3, the torque ripple following circuit of AC motor frequency conversion controller according to claim 1 is characterized by, and further comprises guaranteeing that described voltage detection signal is lower than the pressure limiting circuit of the ceiling value of single-chip microcomputer input; This pressure limiting circuit receives the output of described input circuit, after its pressure limiting, exports to the single-chip microcomputer input port.
4, the torque ripple following circuit of AC motor frequency conversion controller according to claim 1 is characterized by, and described current rectifying and wave filtering circuit comprises rectifier diode (D2), electrochemical capacitor (C3), resistance (R7);
The anode of rectifier diode (D2) connects described sampling current;
Electrochemical capacitor (C3) is in parallel with resistance (R7), wherein is parallel with the negative electrode that the anodal parallel connected end of electrochemical capacitor (C3) connects rectifier diode (D2), another parallel connected end ground connection.
5, the torque ripple following circuit of AC motor frequency conversion controller according to claim 1 is characterized by, and described sample circuit is a current sensor.
6, a kind of method of torque ripple following of AC motor frequency conversion controller is characterized in that, comprises step:
61) detect the alternating current motor electric current;
62) judge whether described alternating current motor current value is higher than default alternating current motor current threshold; If then enter step 63); If not, then enter step 66);
63) this alternating current motor current value of accumulative total is higher than the time of default alternating current motor current threshold;
64) if described alternating current motor current value is higher than the time accumulative total of default alternating current motor current threshold when surpassing predetermined value, read the alternating current motor rotary speed information;
When 65) being lower than rotary speed threshold value, then adjust the output frequency and the voltage of alternating current motor driving power, to reduce electric current by alternating current motor as if the alternating current motor rotating speed; If the alternating current motor rotating speed is normal, then adjust the duty ratio of alternating current motor driving power voltage, to reduce the alternating current motor driving voltage of this alternating current motor driving power output;
66) zero clearing alternating current motor current value is higher than the time accumulated value of default alternating current motor current threshold.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005100753651A CN100488026C (en) | 2005-06-16 | 2005-06-16 | AC motor frequency conversion controller torque ripple following circuit and its method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005100753651A CN100488026C (en) | 2005-06-16 | 2005-06-16 | AC motor frequency conversion controller torque ripple following circuit and its method |
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| CN103076580B (en) | 2011-10-25 | 2016-02-03 | 通用电气公司 | Gradient amplifier, circuit control device, magnetic resonance imaging system and control method |
| CN103078510B (en) | 2011-10-25 | 2015-11-25 | 通用电气公司 | Resonant power, magnetic resonance imaging system and control method |
| CN103078515A (en) | 2011-10-25 | 2013-05-01 | 通用电气公司 | Resonant power supply, converter controller, magnetic resonance imaging system and control method |
| KR102552538B1 (en) * | 2016-12-23 | 2023-07-07 | 한온시스템 주식회사 | Apparatus and method for driving a BLDC motor using compensation of voltage |
| CN113323887A (en) * | 2021-06-01 | 2021-08-31 | 广州大学城投资经营管理有限公司 | Energy-saving device for water pump system of central air conditioner |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4314191A (en) * | 1978-11-04 | 1982-02-02 | Shigeki Kawada | Protective system for inverter circuit used in driving AC motors |
| JP2884776B2 (en) * | 1990-12-26 | 1999-04-19 | 富士電機株式会社 | AC motor commercial / inverter operation switching control method |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4314191A (en) * | 1978-11-04 | 1982-02-02 | Shigeki Kawada | Protective system for inverter circuit used in driving AC motors |
| JP2884776B2 (en) * | 1990-12-26 | 1999-04-19 | 富士電機株式会社 | AC motor commercial / inverter operation switching control method |
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