CN1062691C - Process for a power supply for an inductive load and device embodying this process - Google Patents
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- CN1062691C CN1062691C CN94105726A CN94105726A CN1062691C CN 1062691 C CN1062691 C CN 1062691C CN 94105726 A CN94105726 A CN 94105726A CN 94105726 A CN94105726 A CN 94105726A CN 1062691 C CN1062691 C CN 1062691C
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- 238000000034 method Methods 0.000 title claims abstract description 37
- 230000001939 inductive effect Effects 0.000 title claims abstract description 20
- 230000010349 pulsation Effects 0.000 description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- 229910052742 iron Inorganic materials 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
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- 238000006243 chemical reaction Methods 0.000 description 2
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- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 230000001965 increasing effect Effects 0.000 description 2
- 150000002505 iron Chemical class 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 241000405147 Hermes Species 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
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- 230000004069 differentiation Effects 0.000 description 1
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- 238000012545 processing Methods 0.000 description 1
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- 238000012546 transfer Methods 0.000 description 1
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Abstract
The present invention relates to a method for supplying power to an inductive load, such as a motor, and a control device for implementing the method to supply power to the inductive load and optimize the efficiency of the inductive load and the control device. In the method for supplying power to an inductive load, a voltage (UmLF) exerted to a binding post of the inductive load is obtained by converting a DC voltage (E) into a DC voltage wave, that is, a stable section is in at least a half period. The method for supplying power to an inductive load is suitable for various inductive loads, such as transformers, AC motors, motors with commutators or without commutators and particularly single-phase or multi-phase asynchronous motors.
Description
The present invention relates to a kind of inductive load of giving, for example resemble the method for a motor power supply, and implement the control device of this method, and optimize the efficient of this load and this device to this electric.
The alternating voltage ripple that utilizes frequency conversion and luffing is known for the principle of the such inductive load power supply of motor.Need switch a direct current voltage source in order on connecting terminal of motor, to obtain desired waveform so that make the motor supply power voltage adapt to its load torque.When voltage source is an alternation, when for example taking from electrical network,, insert an intermediate module in order to produce a direct voltage ripple, above-mentioned direct voltage Pohle switches with PWM (pulse width modulation) method, so that desired voltage waveform can be applied on the connecting terminal of motor.If voltage source has been a direct current, it can directly utilize the PWM method to switch.This expert's technique known is described in the book by Yvon PEERS, this book is published by HERMES, " Variation de vitesse " (velocity transformation) by name.
Cause many problems in this way, these problems are present in two aspects, first relevant for " low " frequently, in other words be and the first-harmonic natural frequency of electric moter voltage and the frequency of the same order of magnitude of harmonic wave thereof, in other words another be and the fundamental frequency of PWM and the frequency of the same order of magnitude of harmonic wave thereof at " height " frequently.
On " low " viewpoint frequently, the problem that is run into is the heterogencity of output torque because the air-gap flux that produces in motor is not complete sinusoid, voltage harmonic produced torque harmonic wave, this torque Harmonic Interference torque.These torque pulsations have two class results, promptly acoustically and mechanically.Voltage harmonic produces the torque harmonic wave, and the torque harmonic wave causes pulsation, and this pulsation makes the user be sick of, and can be harmful to the motor environment, and reduces efficiency of motor.
From " height " viewpoint frequently, PWM switches and its harmonic frequency appears on the sound of motor and the pulsation wave band.More irksome on can audible frequency range the time by switching the frequency produced when them, for these noises that decay, use sound arrester, these sound arresters have formed the obstacle that dispels the heat substantially between motor and its environment.
In addition, the reality of superposition PWM method has the result who reduces electric efficiency and further increase temperature on the electric moter voltage first-harmonic, especially when switching frequency was low, the switching dc voltage ripple can be forced on loop inductance with slope declivity oblique a string with switching frequency.Because by the nonlinear amplifier characteristic that stacking plate (plate) constitutes, this sawtooth waveform is exaggerated with the form of magnetic field ripple.Between transfer period, on the normal hysteresis loop of the sinusoidal field that causes iron loss superposition attached loop line, this iron loss lowers efficiency and increases the temperature of stacking plate, has therefore forced restriction on the working range of motor.
PWM switches the conversion of the control device of method inevitable requirement power switching device, and this affirms the reduction with switch cost and power electronics circuit efficient.In order to limit the temperature rise on these power switching devices, must increase the size of heat abstractor, if the reliability of holding device then will increase cost and size.
The width that changes pulse means cut-offfing and closing time of change power switching device.Owing to their processing reason, these power switching devices have the lower closed time limit (ton) and cut-off the time limit (toff), can not correctly work in following switch member of these time limits.Because these restrictions when switching dc voltage E, obtain to equal the resultant voltage peak value of E till the ass ascends the ladder, deviate is caused by minimum ton and toff value.
Particularly such a case when using sinusoidal pattern PWM, requires ton and toff value short as to be enough to respect to the sinusoidal waveform near peak value.Therefore possible is, perhaps with respect to sinusoidal waveform, peak value is not equal to E in the above-mentioned sine-shaped situation, perhaps obtains peak E, and waveform is broken to near its peaked mesa-shaped.Use sinusoidal pattern PWM can obtain 90～95% of voltage E, above-mentioned sinusoidal pattern PWM has switching frequency and the so-called quick electric power triode and the diode of 20KHz level.Relatively the peak value near E only can reach with the reduction switching frequency, but this causes above-mentioned magnetic hysteresis loss and pulsation phenomenon.Therefore, draft two kinds of solutions for constant power of motor, promptly or for deviation compensation is worked with higher voltage E, but require power switch to be operated on the higher voltage, perhaps for the modification motor windings of on more reliable voltage, working, but in this case, winding will be drawn more electric current, and these electric currents transmit by power switching device.In both of these case, the solution of being drafted is all harmful to power switch.
Developed multiple employing PWM method the method for required voltage to the motor terminals is provided.
China Patent No. is the wave method that cuts that discloses a kind of PWM frequency control that is used for induction machine in the application documents of CN1055629A.According to this method, angle γ (cutting wave angle), β (the preceding angle of flow) and α (the back angle of flow) will specifically determine at the speed governing of motor.
Yet all these schemes all can not reduce the harmonic wave component that is lower than a very low level voltage fundamental frequency effectively, especially can not eliminate three grades of harmonic waves that cause maximum interference usually effectively.
The object of the present invention is to provide a kind of method and apparatus of powering, provide a specific voltage waveform by terminals, thereby overcome above-mentioned defective to inductive load to the terminals of inductive load.
The method of supplying power to of alternating voltage is provided according to a kind of terminals to inductive load provided by the present invention, the low-frequency voltage (UmLF) that comprises a generation from the described alternating voltage of dc voltage (E) (direct voltage (E)), described method comprises: switch described dc voltage, thereby the low-frequency voltage that is produced has a steady section at the peak value place of each half cycle of described low-frequency voltage, described method is characterised in that, each half cycle of low-frequency voltage (UmLF) of described generation that is applied to the terminals of described inductive load has the shape of an isosceles trapezoid, these isosceles are trapezoidal to be comprised one and goes up oblique slope, the slope of a steady section and a declivity, the described oblique slope and the slope of declivity obtain by switching described dc voltage (E) according to high-frequency PWM (pulse width modulation) method, and the feature of described method also is, be T/6 the perdurabgility of the described steady section of each half cycle T/2, wherein T is the primitive period of the low-frequency voltage (UmLF) of described generation, and described steady section does not switch described dc voltage (E) and obtains.
According to a kind of motor power control device that an alternating voltage from dc voltage (E) (Um) is provided to motor provided by the present invention, described device comprises: by the switching device shifter of assembly control, wherein said assembly comprises according to the high-frequency PWM method controls described switching device shifter to generate the device of the low frequency component (UmLF) that is produced in the described alternating voltage (Um), the described low frequency component (UmLF) that produces is in each half cycle T/2, have one and go up oblique slope, the steady section of a continuity T/6 time and the slope of a declivity, wherein T is the primitive period of the low frequency component of described generation, switched by described switching device shifter during the slope of described dc voltage (E) oblique slope and described declivity described, and during described steady section, do not switch and be applied to described motor.
By reading, can understand the present invention preferably, and additional advantage will become clear clear by the graphic explanation of following accompanying drawing:
Fig. 1 represents the waveform of exporting to motor of an optimised form of the method according to this invention.
Fig. 2 represents to be used for implementing a device of the method according to this invention.
In the following description, inductive load is seen as a motor, the voltage U m that is applied on this connecting terminal of motor has such component, UmLF, be the low-frequency voltage on the connecting terminal of motor, in other words be and the fundamental frequency of electric moter voltage or frequency and another component UmHF of the same order of magnitude of its harmonic wave, be the high frequency voltage on the connecting terminal of motor, in other words be and the fundamental frequency of PWM switching or the frequency of the same order of magnitude of its harmonic wave.
Figure among Fig. 1 is an abscissa with time t, is ordinate with the resultant voltage ripple UmLF value that imposes on the connecting terminal of motor 8.Present invention resides on the connecting terminal of motor 8 and to produce a voltage wave Um, this voltage wave is switched by a direct voltage E and gets, and this voltage wave is at least on a half cycle, and being preferably on the peak position of this half cycle has a steady section 4.According to the present invention, this voltage wave can be an alternation, the shape that can have a mind between each steady section, for example it can be a slope, sine curve, index or a tangent cutve, the perhaps shape of the differentiation of any kind of of sine curve, index or tangent cutve.Best selected waveform is similar to shape shown in Figure 1, wherein selects an interesting especially shape 1 on half cycle according to the present invention, and is promptly trapezoidal.Go up oblique 2 and the slope of declivity 3 get by utilizing known pulse width modulation (PWM) type device that a direct voltage E is switched.
Because this trapezoidal shape of UmLF voltage wave requires only switching dc voltage source voltage E during slope 2 and 3, so during steady section 4, carry out the optimum utilization of voltage source E by on connecting terminal of motor, obtaining same voltage source voltage E.We have understood the switching that continues that utilizes PWM, in limited power switch closing time ton and switch off time toff, can not reach the resultant voltage peak value that equals E.Suppose that for the waveform of closing near peak the voltage deviation value is 7% the order of magnitude, for same power of motor, the shape of UmLF voltage wave has two class advantages on existing solution.First is to use ratio converter input voltage of low about 7% when switching the waveform obtained with sine pulse width modulation (PWM), make that the voltage that imposes on electric power assembly is also lower, the secondth, constant if the converter input voltage keeps, increase the electric current about 7% that absorbs at the voltage waveform that switches, and therefore increase under the situation of the electric current that flows through electric power assembly, can limit a lower voltage to motor.
Equally, this trapezoidal shape 1 can reduce the switch cost owing to power switch spare in this device, this is because they are not switched during the perdurabgility of whole steady section 4, makes the efficient of this device increase, and the surface area of the heat abstractor that is connected and the cost of device also are lowered.
Fig. 1 represents a kind of optimum shape of this trapezoidal wave half cycle, i.e. isosceles trapezoid.
Another important feature of the present invention is employed frequency values.In best mode of the present invention, the switching frequency of whole slope in perdurabgility is greater than 20KHz.During these slopes, can use whole frequency values, but for higher switching frequency, especially the switching frequency more than the value of 10KHz grade can increase potential advantage.
From these " height " viewpoint frequently, switch output frequency and produce less pulsating wave, these pulsating waves become and are easier to a higher frequency filtering.When moving on being higher than the frequency of 20KHz, the voltage wave switching device shifter can be avoided additional sound arrester, and this sound arrester can reduce the heat exchange between motor and its environment.Therefore increased the motor reliability, made it in the working range of a broad, to use.Same because pulsation is than being easier to a higher frequency elimination, and the design of coupling element can be simplified, and this coupling element plays damping action between motor and its strutting piece.
In addition, the amplitude of above-mentioned relevant magnetic hysteresis loop is smaller on these switching frequencies, also can reduce the iron loss in the motor core, and this iron loss can make the rising of stacking plate temperature.Height when therefore this electric efficiency is hanged down switching frequency than use.
Though on this slope 2 and 3 or perdurabgility of steady section 4 without limits, but another critical nature of the present invention is to be applied to the perdurabgility of the steady section of the voltage wave UmLF on the connecting terminal of motor 8 with respect to its cycle, the trapezoidal wave that can be isosceles does not have harmonic wave, wherein steady section has the perdurabgility of T/6, at this, T is the primitive period of voltage wave UmLF.Above-mentioned harmonic wave is meant and accounts for the harmonic wave of total effective value more than 3% that in fact triple-frequency harmonics does not exist in practice.
This not additional any above-mentioned those magnetic air gap voltage harmonics of isosceles trapezoid with T/6 steady section, these harmonic waves obtain when powering to motor with a pure sine wave.
Resemble this special trapezoidal of the above-mentioned waveform with steady section and can limit the torque pulsation that causes owing to harmonic losses in the motor, these harmonic losses are the main causes that cause mechanical oscillation harmful on above-mentioned " low " frequency and audio frequency pulsation.Obtain an evenly normal torque by producing air-gap flux.Utilize this air-gap flux of motor supply power voltage as much as possible near sine curve, the motor supply power voltage is as much as possible near the first-harmonic of its Fourier expansion.These special features avoid increasing harmonic losses, thereby reduce because the power consumption that the switching of power switching device causes.
The present invention also relates to implement a device of said method.This device is indicated among Fig. 2.
If voltage source U be alternation rather than direct current, a rectifying device 5 switches to direct voltage E to alternating voltage Ue.This rectifying device 5 can be a kind of common bridge diode rectifier or any known device, apply the alternating source voltage U at this, and rectifier is preferably exported a direct current voltage by a filter, this filter is made of an inductance L and a capacitor C, inductance L restriction current peak, the capacitor C voltage after to rectification carries out filtering.
The direct voltage E that is obtained is applied on a switching device shifter 6 and the power diode by 7 controls of direct voltage E changeover module, and this assembly 7 can be a PWM type assembly.To the known controlled switching device shifter 6 of expert of the art, this assembly output voltage U mLF gives connecting terminal of motor 8 by means of a cover, and the characteristic of this voltage as shown in Figure 1.In other words, the half cycle shape of this voltage wave UmLF has a steady section, this steady section preferably is positioned on its crest, it can be trapezoidal, isosceles, or any other shape in the said method explanation, this waveform is by obtaining to be preferably in the frequency switching dc voltage E more than the 10KHz during slope perdurabgility of composite wave.Be T/6 the perdurabgility of its steady section, is the cycle of resultant voltage UmLF at this T.
The present invention is applicable to various types of inductive loads, as transformer and alternating current motor, is with or without the motor of commutator, especially single-phase or heterogeneous asynchronous motor.
Claims (4)
1, a kind of terminals to inductive load provide the method for supplying power to of alternating voltage, the low-frequency voltage (UmLF) that comprises a generation from the described alternating voltage of dc voltage (E) (direct voltage (E)), described method comprises: switch described dc voltage, thereby the low-frequency voltage that is produced has a steady section at the peak value place of each half cycle of described low-frequency voltage, described method is characterised in that, each half cycle of low-frequency voltage (UmLF) of described generation that is applied to the terminals of described inductive load has the shape of an isosceles trapezoid, these isosceles are trapezoidal to be comprised one and goes up oblique slope, the slope of a steady section and a declivity, the described oblique slope and the slope of declivity obtain by switching described dc voltage (E) according to high-frequency PWM (pulse width modulation) method, and the feature of described method also is, be T/6 the perdurabgility of the described steady section of each half cycle T/2, wherein T is the primitive period of the low-frequency voltage (UmLF) of described generation, and described steady section obtains not switching described dc voltage (E).
2, the terminals to inductive load as claimed in claim 1 provide the method for supplying power to of alternating voltage, and wherein said PWM switches high frequency greater than 10kHz.
3, a kind of motor power control device that an alternating voltage from dc voltage (E) (Um) is provided to motor (8), described device comprises: by the switching device shifter (6) of assembly (7) control, wherein said assembly comprises according to the high-frequency PWM method controls described switching device shifter to generate the device of the low frequency component (UmLF) that is produced in the described alternating voltage (Um), the described low frequency component (UmLF) that produces is in each half cycle T/2, have one and go up oblique slope, the steady section of a continuity T/6 time and the slope of a declivity, wherein T is the primitive period of the low frequency component of described generation, switched by described switching device shifter during the slope of described dc voltage (E) oblique slope and described declivity described, and during described steady section, do not switch and be applied to described motor.
4, motor power control device as claimed in claim 3, wherein said assembly is controlled described switching device shifter, thus described going up oblique slope, the slope of declivity and the perdurabgility that steady section all has T/6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94105726A CN1062691C (en) | 1994-05-17 | 1994-05-17 | Process for a power supply for an inductive load and device embodying this process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94105726A CN1062691C (en) | 1994-05-17 | 1994-05-17 | Process for a power supply for an inductive load and device embodying this process |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1114087A CN1114087A (en) | 1995-12-27 |
| CN1062691C true CN1062691C (en) | 2001-02-28 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN94105726A Expired - Fee Related CN1062691C (en) | 1994-05-17 | 1994-05-17 | Process for a power supply for an inductive load and device embodying this process |
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| Country | Link |
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| CN (1) | CN1062691C (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1055627A (en) * | 1990-04-13 | 1991-10-23 | 沈太福 | Double rotor speed regulating motor device and speed regulating method thereof |
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1994
- 1994-05-17 CN CN94105726A patent/CN1062691C/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1055627A (en) * | 1990-04-13 | 1991-10-23 | 沈太福 | Double rotor speed regulating motor device and speed regulating method thereof |
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| Publication number | Publication date |
|---|---|
| CN1114087A (en) | 1995-12-27 |
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Granted publication date: 20010228 Termination date: 20130517 |