CN101378245A - Control method and device for induction machine - Google Patents
Control method and device for induction machine Download PDFInfo
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- CN101378245A CN101378245A CNA2007101314631A CN200710131463A CN101378245A CN 101378245 A CN101378245 A CN 101378245A CN A2007101314631 A CNA2007101314631 A CN A2007101314631A CN 200710131463 A CN200710131463 A CN 200710131463A CN 101378245 A CN101378245 A CN 101378245A
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Abstract
The invention relates to a motor control technology, in particular to an induction motor control method and a realizing device thereof; the method mainly comprises the steps: the actual power factor under the current working frequency and the current working load of the induction motor is detected in real time, the detected actual power factor is compared with the optimal power factor under the current working frequency and the current working load, the working voltage of the induction motor is regulated to cause the actual power factor to be equal to the optimal power factor. The realizing device mainly comprises a current mutual inductor for measuring induction motor parameters, an adder, a processing part, a presetting part, a function converting circuit, a multiplier, a power factor comparator, an output signal generating circuit and a driving circuit. The method and the device solve the problem that the prior art can not cause the motor to work on the optimal power factor all the time under the condition of great change of the load of the motor, thus guaranteeing that the induction motor runs in the optimal state, and having significant energy-saving effect.
Description
Technical field
The present invention relates to a kind of control method and implement device thereof of induction machine.
Background technology
Under the current techniques condition, turn round under the situation of load wide variation basic skills with the raising operational efficiency of control induction machine is that real-time load at motor applies corresponding suitable driving voltage.If the too high magnitude of voltage (required relatively Motor torque) of correspondence during the motor underload, then motor working current is excessive, and operating efficiency reduces.If but under such situation brownout, then the motor load that increases suddenly may cause shutting down or other unsettled working conditions.The power supply that multiple scheme is used for controlling induction machine has been proposed, so that the maximization operating efficiency in the prior art.Yet, these schemes or prevent to shut down or other unstable situations when being difficult in the low load of induction machine usually, otherwise in consume power excessively under the low loading condition.
Current techniques provides a Control of Induction Motors method, and the power factor (PF) of this method when detecting motor rotation with this supply voltage of controlling motor, remains on preset value with power factor (PF).If motor is to work under high load condition, voltage is suitable, and then the corresponding power factor also is suitable.If the increase load, then the hysteresis between current of electric and the voltage will increase, and therefore, power factor (PF) will reduce.On the contrary, the increase that reduces to cause power factor (PF) of motor load.Therefore, the change of motor load can detect by the change of power factor (PF), and then according to the change control supply voltage that detects load, so that power factor (PF) is remained on preset value.Yet in practical operation, for such method, if select the power factor (PF) of full load motor rotation to be default optimum value, the voltage that applies during the running of motor underload is not best for this load value.Equally, when machine operation during, not suitable for this load value voltage in the medium level load.
Another method of current Control of Induction Motors is a frequency conversion drive.For arbitrary particular drive frequency, its control principle is identical with above description.Difference is to select according to different driving frequency needs the different preset values of power factor (PF).But, under arbitrary particular drive frequency, still there are the problems referred to above, promptly only when applying certain loads when (being called " standard termination "), motor will turn round with the optimal power factor.That can not guarantee to operate on large-scale motor variable load is efficient and stable.
Above-mentioned argumentation will be with reference to figure 1 explanation, and wherein curve B is represented the optimal value of the power factor (PF) of the induction machine from non-loaded to full load (100%).The optimal power factor of supposing the full load operation is 80%.For the inductive motor control system of above-mentioned prior art, the power factor Be Controlled remains on 80% value (that is dotted portion A).Yet when the load operation with full load 50%, the optimal power factor is actually 64%, and under no-load condition, system will power factor remain on 80%.As seen, optimal power factor preset value of the prior art is the optimal value under the characteristic frequency standard termination, rather than the optimal value under any current frequency and the present load, this control method can not provide optimum operating efficiency on the motor load of wide variation.
Summary of the invention
Technical problem to be solved by this invention provides a kind of control method and implement device thereof of induction machine, guarantee that machine operation is at different frequency, during the operating load wide variation, the actual power factor of motor is always the optimal power factor of current frequency and present load, thereby make motor to work in the optimal power factor value on a large scale in the interior load that changes continuously, guarantee under the load state of wide variation, all to turn round with maximum efficiency.
The technical solution adopted in the present invention is:
The Control of Induction Motors method is converted to dc voltage AC voltage and offers motor by the DC-AC inverter, the level-variable of AC voltage, and can select a plurality of suitable frequencies.
Detect the actual power factor value of induction machine under work at present frequency and work at present load in real time.
With the optimal power factor value under detected actual power factor value and this current operating frequency and the work at present loading condition relatively.
Adjust the operating voltage of induction machine in real time according to comparative result, the actual power factor value is equated with the optimal power factor value.
Wherein, by the operating current of real-time detection induction machine and the actual power factor value under operating voltage acquisition motor work at present frequency and the work at present load.
Determine different power factor (PF) preset values and power factor compensation value according to different operating loads and operating frequency, with the product of power factor (PF) preset value under work at present frequency and the work at present load and power factor compensation value as the optimal power factor value.
Regulate the amplitude of output AC voltage according to comparing actual power factor value and optimal power factor value gained difference, make the actual power factor value be tending towards equating with current optimal power factor value.
The device of realizing described method comprises current transformer CT1, CT2, adder, power factor (PF) detection and processing unit, power factor (PF) preset component, function conversion circuit, multiplier, power factor (PF) comparator, output signal generation circuit, drive circuit.
Current transformer CT1, CT2 is connected with the three-phase power line of induction machine respectively with adder, the output signal input power factor of current transformer and adder detects and processing unit, multiplier is imported in the power factor compensation value output that the power factor (PF) preset value output and function change-over circuit that the power factor (PF) preset component produces produces together, the optimal power factor value of multiplier output and the actual power factor value that power factor (PF) detects and processing unit is exported be the input power factor comparator together, power factor (PF) comparator output deliver to output signal generation circuit, the output of output signal generation circuit is sent drive circuit and is controlled induction machine.
Good effect of the present invention is:
The present invention by detecting induction machine the actual power factor and with work at present frequency work at present load optimal power factor comparison down, control the voltage levvl of induction machine according to comparative result, thereby change the supply voltage levvl according to the variation of motor load.Power factor (PF) is adjusted continuously according to the variation of motor load, and the working condition of motor remains on the optimal power factor under the present load always.Thereby make motor to work in the optimal power factor value on a large scale in the interior load that changes continuously, guarantee under the load state of wide variation all with maximum efficiency running, energy-conservation electric energy.
Description of drawings
Fig. 1 is a graph of relation between optimal power factor and the motor load,
Fig. 2 is power factor compensation value and an electric moter voltage graph of a relation under the different frequency,
Fig. 3 is the block diagram of implement device of the present invention.
Embodiment
The Control of Induction Motors method is as follows: by the DC-AC inverter dc voltage is converted to AC voltage and offers motor, and the level-variable of AC voltage, and can select a plurality of suitable frequencies.
Detect the actual power factor of induction machine under work at present frequency and work at present load in real time.
With the optimal power factor under detected actual power factor and this current operating frequency and the work at present loading condition relatively.
Adjust the operating voltage of induction machine in real time according to comparative result, the actual power factor is equated with the optimal power factor.
When specifically implementing, can be by the real-time operating current of induction machine and the actual power factor under operating voltage acquisition motor work at present frequency and the work at present load of detecting.
Determine different power factor (PF) preset values and power factor compensation value according to different operating loads and operating frequency, with the product of power factor (PF) preset value under work at present frequency and the work at present load and power factor compensation value as the optimal power factor value.
Regulate the amplitude of output AC voltage according to comparing actual power factor value and optimal power factor value gained difference, make the actual power factor value be tending towards equating with current optimal power factor value.
Specifically, under a particular drive frequency,
The power factor (PF) of continuous detecting machine operation by and with default power factor (PF) relatively, this default power factor (PF) is the optimal power factor at particular drive frequency and particular motor load value.Aforementioned default power factor (PF) is adjusted by multiply by certain offset, this offset in 0 to 1 scope, and be according to this moment electric moter voltage level determine.For example, when the motor-driven frequency was 50Hz, the relation between power factor compensation value and the electric moter voltage was shown in the curve C among Fig. 21.As shown in the figure, the power factor compensation value reduces according to reducing of electric moter voltage, promptly reduces according to reducing of motor load level.By such method, just can along with motor load changes, determine the optimal power factor under present load according to curve as shown in Figure 1.
The optimal power factor changes according to driving frequency with respect to the variation characteristic of motor power voltage under the frequency conversion situation.Therefore, need to use Fig. 2 to represent relation curve between power factor compensation value and the motor power voltage, wherein C2 and C3 are the change curves that driving frequency is respectively 25Hz and 12Hz, and other frequencies are similar.The excursion of motor power voltage value changes according to driving frequency.
The device of realizing described method comprises current transformer CT1, CT2, adder, power factor (PF) detection and processing unit, power factor (PF) preset component, function conversion circuit, multiplier, power factor (PF) comparator, output signal generation circuit, drive circuit.
As shown in Figure 3, current transformer CT1, CT2 is connected with the three-phase power line of induction machine respectively with adder, the output signal input power factor of current transformer and adder detects and processing unit, multiplier is imported in the power factor compensation value output that the power factor (PF) preset value output and function change-over circuit that the power factor (PF) preset component produces produces together, the optimal power factor value of multiplier output and the actual power factor value that power factor (PF) detects and processing unit is exported be the input power factor comparator together, power factor (PF) comparator output deliver to output signal generation circuit, the output of output signal generation circuit is delivered to drive circuit and is controlled induction machine.
In Fig. 3, from current transformer CT1, CT2 receives motor current value Iu, Iw and Iv.Adder is used to obtain magnitude of voltage Vuv, Vwv.These magnitudes of voltage are and current value I u, and Iw and Iv offer together that power factor (PF) detects and processing unit, thereby these parts obtain the realtime power factor of motor by detection electric current and magnitude of voltage.Default power factor (PF) value is produced by the power factor (PF) preset component as input, and can adjust so that set up required default power factor (PF) value.Default power factor (PF) value is imported into multiplier, multiply by the offset that produces from function conversion circuit then.Function conversion circuit reality is made up of many covers memory and the numerical tabular in memory, and each table is corresponding to specific motor-driven frequency values.Therefore each transfer function is to set up for different driving frequency values.It is to carry out by reading offset according to the value of Vuv (RMS) from a table that the power factor compensation value is obtained in conversion.For easy to understand, shown Vuv (RMS) obtains by effective value change-over circuit (its effect is that input voltage is carried out " square → average → extract square root " computing), in fact need obtain Vuv (RMS) in the process of the power factor (PF) value of obtaining measurement.Power factor (PF) of measuring and the difference between the optimal power factor value obtain by the power factor (PF) comparator, and this difference value as a comparison is provided for output signal generation circuit.The response of output signal generation circuit produces output signal with control Driver Circuit.One group of 3 phase switch controlling signal takes place in drive circuit.These drive signals are provided for three switch elements of DC-AC inverter, thereby the dc voltage that the AC-DC transducer is produced is converted to one group of 3 phase voltage, and this voltage will offer induction machine.
In this embodiment, the motor-driven frequency is (simple in order to describe by the frequency indicating device, these parts omit from accompanying drawing) decision, this frequency indicating device is also determined the function that (driving frequency according to the rules) selected SCMD number conversion circuit uses, thereby by selecting in aforementioned a plurality of offset table one that Vuv is converted to corresponding power factor compensation value.
Be appreciated that, the present invention compares by measuring between power of motor factor and the optimal power factor, the control motor power voltage, make the power factor (PF) of induction machine working point remain on optimal value continuously, can realize stable operation and minimal power consumption in low loading condition following time in motor operation according to the load of motor.
Under the characteristic frequency; the supply voltage of motor can provide enough moments of torsion at full capacity; balanced load can not provide simultaneously too high voltage (overpower consumption) during underload, and the low-voltage under this light-load conditions can not cause motor operation to be shut down or unstable simultaneously.In the frequency conversion drive application scenario of induction machine, any motor load value correspondent voltage will change according to driving frequency.
When the load height that is applied to induction machine changed, the present invention can provide the energy-conservation of highly significant.
Claims (3)
1, Control of Induction Motors method is converted to dc voltage AC voltage and offers motor by the DC-AC inverter, the level-variable of AC voltage, and can select a plurality of suitable frequencies, it is characterized in that:
Detect the actual power factor value of induction machine under work at present frequency and work at present load in real time,
With the optimal power factor value under detected actual power factor value and this current operating frequency and the work at present loading condition relatively,
Adjust the operating voltage of induction machine in real time according to comparative result, the actual power factor value is equated with the optimal power factor value.
2, Control of Induction Motors method as claimed in claim 1 is characterized in that:
By the operating current of real-time detection induction machine and the actual power factor value under operating voltage acquisition motor work at present frequency and the work at present load,
Determine different power factor (PF) preset values and power factor compensation value according to different operating loads and operating frequency, with the product of power factor (PF) preset value under work at present frequency and the work at present load and power factor compensation value as the optimal power factor value,
Regulate the amplitude of output AC voltage according to comparing actual power factor value and optimal power factor value gained difference, make the actual power factor value be tending towards equating with current optimal power factor value.
3, realize the device of method according to claim 1, comprise current transformer CT1, CT2, adder, power factor (PF) detection and processing unit, power factor (PF) preset component, function conversion circuit, multiplier, power factor (PF) comparator, output signal generation circuit, drive circuit
Current transformer CT1, CT2 is connected with the three-phase power line of induction machine respectively with adder, the output signal input power factor of current transformer and adder detects and processing unit, multiplier is imported in the power factor compensation value output that the power factor (PF) preset value output and function change-over circuit that the power factor (PF) preset component produces produces together, the optimal power factor value of multiplier output and the actual power factor value that power factor (PF) detects and processing unit is exported be the input power factor comparator together, power factor (PF) comparator output deliver to output signal generation circuit, the output of output signal generation circuit is sent drive circuit and is controlled induction machine.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2007101314631A CN101378245A (en) | 2007-08-28 | 2007-08-28 | Control method and device for induction machine |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2007101314631A CN101378245A (en) | 2007-08-28 | 2007-08-28 | Control method and device for induction machine |
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| CN101378245A true CN101378245A (en) | 2009-03-04 |
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| CNA2007101314631A Pending CN101378245A (en) | 2007-08-28 | 2007-08-28 | Control method and device for induction machine |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108023528A (en) * | 2016-11-04 | 2018-05-11 | 上海儒竞电子科技有限公司 | The dynamic energy-saving speed regulating method and system of permasyn morot |
| CN110393472A (en) * | 2018-04-25 | 2019-11-01 | 添可电器有限公司 | Dust catcher |
-
2007
- 2007-08-28 CN CNA2007101314631A patent/CN101378245A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108023528A (en) * | 2016-11-04 | 2018-05-11 | 上海儒竞电子科技有限公司 | The dynamic energy-saving speed regulating method and system of permasyn morot |
| CN110393472A (en) * | 2018-04-25 | 2019-11-01 | 添可电器有限公司 | Dust catcher |
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Open date: 20090304 |