CN1387313A - Harmonic utilizing scheme for variable-frequency AC induction motor - Google Patents
Harmonic utilizing scheme for variable-frequency AC induction motor Download PDFInfo
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Abstract
The present invention discloses a scheme for utilizing harmonic wave in order to improve the performance of the induction ac motor of variable frequency based on detailed research. The following performances are improved. (1) The rotary magnetic potential formed by the harmonic current in low order has the same rotary speed of the fundamental harmonic rotary magnetic potential. Thus, the low order harmonic currents are not needed to eliminate so as to lower the switchnig frequency, power dissipation and to prolong service life of the electric switch parts. (2) The rotary magnetic potential of the third harmonic wave is properly controlled, since it is synchronous with the fundamental harmonic rotary magnetic potential so as to increase the power of the motor, reduces the possibility of magnetic over saturation.
Description
The present invention relates to a kind of induction alternating current (AC) motor and frequency-converting speed-governing control system thereof.
Along with development of electronic technology, the induction alternating current (AC) motor of frequency control is used widely in every field, has replaced DC motor to a certain extent.In the induction motor frequency control, the influence of harmonic current and harmonic magnetic potential is distinct issues.Overcoming the method for harmonic current at present, is exactly the break-make moment of accurate Control current, so that the approaching as far as possible sinusoidal state of electric current, this just needs to increase the break-make frequency of device for power switching, thereby causes device for power switching heating loss rising.And for harmonic magnetic potential, this is determined that by motor stator structure and winding elimination is limited, and it can cause the motor vibrations, and produces stray loss.The present invention is directed to this problem, propose a kind of variable-frequency AC induction motor harmonic wave and utilize scheme, the influence of rudimentary subharmonic current and rudimentary subharmonic magnetic potential is eliminated, and can keep rudimentary subharmonic current and the synthetic useful rotating magnetic potential of rudimentary subharmonic magnetic potential; Simultaneously, utilize the rotating magnetic potential and the first-harmonic rotating magnetic potential superposition of triple-frequency harmonics, with under the power situation, reduced the maximum of magnetic flux density in the iron core of electric motor very greatly, can reduce the magnetic hysteresis loss of motor undoubtedly, utilize this characteristics,, also can improve its power output if keep the maximum magnetic induction of motor constant.
In order to illustrate design of the present invention, the harmonic problem in the three phase induction motor is discussed at first:
If any one feeds unitary current mutually in the three phase induction motor, in the magnetic air gap of motor, produce the distribution magnetic potential, because the positive and negative half period of magnetic potential rotation symmetry, positive half period or negative half-cycle first half and latter half symmetry, but thereby in the magnetic air gap the following trigonometric function of the magnetic potential generate of the unitary current of A, B, C three-phase express formula:
F
B=f
1cos(α-120°)+f
3cos3(α-120°)+f
5cos5(α-120°)+…
=
[f
(6n-5)cos(6n-5)(α-120°)+f
(6n-3)cos(6n-3)(α-120°)+f
(6n-1)cos(6n-1)(α-120°)]
F
C=f
1cos(α-240°)+f
3cos3(α-240°)+f
5cos5(α-240°)+…
Above-mentioned α represents the position angle coordinate of magnetic air gap mid point.
And A, B, C three-phase current also can be launched into trigonometric function and express formula (not containing 3 integral multiple subharmonic):
I
B=I
1cos(ωt-120°)+I
5cos5(ωt-120°)+I
7cos7(ωt-120°)+...
I
C=I
1cos(ωt-240°)+I
5cos5(ωt-240°)+I
7cos7(ωt-240°)+...
(2)
Be similar to and think that the motor magnetization process is linear, thereby in the magnetic air gap, each phase magnetic potential is that corresponding is long-pending in above-mentioned (1), (2) formula: F
A(α, t)=F
AI
A=
[f
(6n-5)Cos (6n-5) α+f
(6n-3)Cos (6n-3) α+f
(6n-1)Cos (6n-1) α] }
[I
(6m-5)Cos (6m-5) ω t+I
(6m-1)Cos (6m-1) ω t}}=
f
(6n-5)I
(6m-5)Cos (6n-5) α cos (6m-5) ω t++f
(6n-3)I
(6m-5)Cos (6n-3) α cos (6m-5) ω t+f
(6n-1)I
(6m-5)Cos (6n-1) α cos (6m-5) ω t++f
(6n-5)I
(6m-1)Cos (6n-5) α cos (6m-1) ω t+f
(6n-3)I
(6m-1)Cos (6n-3) α cos (6m-1) ω t+f
(6n-1)I
(6m-1)Cos (6n-1) α cos (6m-1) ω tF
B(α, t)=F
BI
B=
[f
(6n-5)Cos (6n-5) (α-120 °)+f
(6n-3)Cos (6n-3) (α-120 °)+f
(6n-1)Cos (6n-1) (α-120 °) } }
[I
(6m-5)Cos (6m-5) (ω t-120 °)+I
(6m-1)Cos (6m-1) (ω t-120 °) } }=
[f
(6n-5)I
(6m-5)Cos (6n-5) (α-120 °) cos (6m-5) (ω t-120 °)+f
(6n-3)I
(6m-5)Cos (6n-3) (α-120.)cos(6m-5)(ωt-120°)++f
(6n-1)I
(6m-5)cos(6n-1)(α-120°)cos(6m-5)(ωt-120°)+f
(6n-5)I
(6m-1)cos(6n-5)(α-120°)cos(6m-1)(ωt-120°)++f
(6n-3)I
(6m-1)cos(6n-3)(α-120°)cos(6m-1)(ωt-120°)+f
(6n-1)I
(6m-1)cos(6n-1)(α-120°)cos(6m-1)(ωt-120°)]F
C(α,t)=F
CI
C={
[f
(6n-5)cos(6n-5)(α-240°)+f
(6n-3)cos(6n-3)(α-240°)+f
(6n-1)cos(6n-1)(α-240°)}}{
[I
(6m-5)cos(6m-5)(ωt-240°)+I
(6m-1)cos(6m-1)(ωt-240°)]}=
[f
(6n-5)I
(6m-5)cos(6n-5)(α-240°)cos(6m-5)(ωt-240°)+f
(6n-3)I
(6m-5)cos(6n-3)(α-240°)cos(6m-5)(ωt-240°)++f
(6n-1)I
(6m-5)cos(6n-1)(α-240°)cos(6m-5)(ωt-240°)+f
(6n-5)I
(6m-1)cos(6n-5)(α-240°)cos(6m-1)(ωt-240°)++f
(6n-3)I
(6m-1)*cos(6n-3)(α-240°)cos(6m-1)(ωt-240°)+f
(6n-1)I
(6m-1)cos(6n-1)(α-240°)cos(6m-1)(ωt-240°)]
(3)
In the following formula three-phase magnetic potential all radially along air gap, following formula three formula additions, be exactly Zong in the air gap magnetic potential distribute: F=F
A(α, t)+F
B(α, t)+F
C(α, t)==
{ 1.5f
(6n-5)I
(6m-5)Cos[(6n-5) the ω t of α-(6m-5)]+1.5f
(6n-1)I
(6m-5)Cos[(6n-1) the ω t of α+(6m-5)] ++ 1.5f
(6n-5)I
(6m-1)Cos[(6n-5) α+(6m-1)] ω t}+1.5f
(6n-1)I
(6m-1)Cos[(6n-1) the ω t of α-(6m-1)]
(4)
Each all represents a rotating magnetic potential in the following formula, but that their rotary speed and direction have is different, is respectively for first, fourth its angular speed:
For second and third, its angular speed is respectively:
(5), (6) formula is represented the angular speed that is rotated in the forward, when fraction molecule and denominator equate especially on the right, its rotary speed ω, for example synthetic separately its rotary speed of rotating magnetic potential (becoming first-harmonic rotating magnetic potential, quintuple harmonics rotating magnetic potential, the seventh harmonic rotating magnetic potential respectively) of fundamental current and fundamental magnetic potential, quintuple harmonics electric current and quintuple harmonics magnetic potential, the seventh harmonic electric current and the seventh harmonic magnetic potential is ω, and these all work to the running of motor.Its rotary speed ω not just when but the right fraction molecule and denominator are unequal, for example the synthetic rotating magnetic potential rotary speed of the seventh harmonic electric current and fundamental magnetic potential is 7 ω, and the synthetic rotating magnetic potential rotary speed of fundamental current and the seventh harmonic magnetic potential is (1/7) ω.The rotary speed of these rotating magnetic potentials first-harmonic rotating magnetic potential rotary speed of all getting along well is synchronous.Revolutional slip s approaches 1 or less than 0, efficient is extremely low.
(7), (8) formula represents the angular speed of negative sense rotation, its revolutional slip s is greater than 1, they play braking action to motor rotation.For example the synthetic rotating magnetic potential rotary speed of fundamental current and quintuple harmonics magnetic potential is (1/5) ω, and the synthetic rotating magnetic potential rotary speed of quintuple harmonics electric current and fundamental magnetic potential is (5) ω.
Fig. 1 visual representation above result of calculation, the circle symbol among the figure shown in 11, the synthetic rotating magnetic potential of harmonic current that representative is shown by the tabulation at the harmonic magnetic potential of its place line display and place rotates with ω speed.And the triangle symbol shown in 12, it is identical to represent above-mentioned rotating magnetic potential and ω to turn to, but asynchronous.Square symbol shown in 13 is represented above-mentioned rotating magnetic potential and ω switched in opposite.On behalf of above-mentioned rotating magnetic potential, the lines shown in 14 do not exist.Can see obviously that by figure exist the synthetic rotating magnetic potential of a large amount of rudimentary subharmonic currents and rudimentary subharmonic magnetic potential in three-phase alternating-current induction motor, they are asynchronous with the fundamental magnetic potential rotary speed, and negative effect is in various degree played in the running of motor.Even there is not rudimentary subharmonic in the electric current, but the harmonic magnetic potential of motor always exists, and it and fundamental current still form and the nonsynchronous rotating magnetic potential of fundamental magnetic potential, and the harmful effect of motor is still existed.
From top Harmonics Calculation method, can be generalized to any cross streams induction motor is analyzed three-phase alternating-current induction motor.
If q (q>3) is the number of phases of motor, and suppose that q is an odd number, any adjacent two-phase arrangement angle in stator differs 360 °/q, and the phase angle difference that any adjacent two-phase feeds electric current also is 360 °/q, and the magnetic potential of k phase unitary current can be expressed as:
F
k=
f
(2n-1)cos[(2n-1)(α-(k-1)360°/q)] k=1、2、3、…q
The k phase current can be expressed as:
Total magnetic potential is distributed as in the motor gas-gap:
{f
(2n-1)I
(2m-1)cos[(2n-1)(α-(k-1)360°/q)]cos[(2m-1)(ωt-(k-1)360°/q)]}
=
0.5f
(2n-1)I
(2m-1)cos[(2n-1)α-(2m-1)ωt-[(2n-1)-(2m-1)](k-1)(360°/q)]}+
+{
0.5f
(2n-1)I
(2m-1)cos[(2n-1)α+(2m-1)ωt-[(2n-1)+(2m-1)](k-1)(360°/q)]}
=
0.5?q?f
(2n-1)I
(2m-1)cos[(2n-1)α-(2m-1)ωt]+
+
0.5?q?f
(2n-1)I
(2m-1)cos[(2n-1)α+(2m-1)ωt]
Following formula first and number in expression formula represent that angular speed is
Rotating magnetic potential, second and number in expression formula represent that angular speed is
Rotating magnetic potential.Obviously the level of the level time (2m-1) of harmonic current and harmonic magnetic potential is during inferior equating, its angular speed is ω.As can be seen from the above equation, under the situation of (2n-1)+(2m-1)<q, be the rotating magnetic potential of ω except there being angular speed, there is not the rotating magnetic potential of other speed.If q is bigger, the level of the harmonic current of the rotating magnetic potential of synthetic non-ω rotating speed level inferior or harmonic magnetic potential is inferior just bigger, and is just less to the negative effect of motor.Fig. 2 has provided the harmonic wave situation of 15 phase motors, same Fig. 1 of the meaning of symbol among the figure.
When being even number for q, replace 360/q with 180/q during calculating, conclusion is similar with the odd number situation.Above-mentioned in addition current expression has implied the per half period first half and the latter half symmetry of electric current, in fact, does not have this symmetry, still can obtain top conclusion in the polyphase machine calculating, only calculates complicated a little.
Utilize above-mentioned analysis result, we can acquire benefit aspect several: 1, in Electric Machine Control, rudimentary time harmonic current mainly forms the harmonic wave rotating magnetic potential with first-harmonic rotating magnetic potential same rotational speed ω, unnecessary undue elimination, this just can reduce the switching frequency of electronic switching device, and this will cause, and the electronic switching device power consumption reduces, the life-span prolongation; 2, appropriate control triple-frequency harmonics rotating magnetic potential, because it is synchronous with first-harmonic rotating magnetic potential rotary speed, behind the superposition, can reduce the maximum of motor intrinsic inductance, so not only increased power of motor, surpassed saturated possibility but also reduced magnetic material.This will help to improve the margin of power and the overload capacity of motor.3, owing to the increase of the number of phases, although more complicated on the version, single channel electronic switching device capacity greatly reduces, and this has solved high-power, the high-frequency contradiction of electronic switching device from another angle, is easy to realize the heavy-duty motor variable frequency control; 4, owing to overcome rudimentary subharmonic, improved efficiency of motor to the motor negative effect.
Therefore, general plotting of the present invention is:
As shown in Figure 3, the number of phases q of induction alternating current (AC) motor is greater than 3, and the input of every phase winding 1 connects the positive pole and the negative pole of DC power supply respectively by two switching devices 2,3; Switching device 2,3 can be an electronic switching device, can also be the switching device that certain mechanical mechanism constitutes; The input of every phase winding also connects the positive pole of fly-wheel diode 4 and the negative pole of following fly-wheel diode 5, and the negative pole of the positive pole of last fly-wheel diode 4 and following fly-wheel diode 5 is connected respectively to the negative pole and the positive pole of DC power supply again; Any two-phase is flowed into the phase difference of input fundamental current,, equate with electrical degree folded between the input of this two-phase by switching device control.The electric current that flows into every phase winding can comprise rudimentary time harmonic current, particularly triple harmonic current by switching device control.The available following several method of each phase winding other end (hereinafter referred to as the end of winding) connects: (1) all meets (as Fig. 3) altogether, (2) be divided into some groups, each group (for example connects altogether, the winding number of phases is 5 integral multiple, mutual 5 winding ends every 72 ° are connect altogether, are not then contained 5 integral multiple subharmonic composition in each phase winding electric current), (3) are divided into some groups, each group connects altogether, connects end altogether and is connected (as Fig. 5) with other winding again.
The method that below provides a range winding electric machine employing modulation signal realizes the embodiment of Current Control:
If F (α-ω t) is the rotating magnetic potential that harmonic wave rotating magnetic potential superposition that the first-harmonic rotating magnetic potential of ω and a series of plan keep forms for rotating speed, then to a phase wherein, this rotating magnetic potential induced electromotive force is that e can be expressed as:
K is a constant in the following formula.
Be similar to and think that e and terminal voltage u equate, promptly terminal voltage and this synthetic rotating magnetic potential have similar forms.As shown in Figure 4, get modulating wave 40 and have similar shape with motor first-harmonic rotating magnetic potential and the rotating magnetic potential that the rudimentary subharmonic rotating magnetic potential of intending keeping synthesizes, make it and a triangular carrier 41 compare, during the positive half cycle of modulating wave, triangular wave trailing edge and modulating wave intersection point as motor wherein a phase input be connected power positive end the switching device conducting constantly, and the triangular wave rising edge turn-offs the moment with the modulating wave intersection point as the switching device that this phase input is connected power positive end; During the modulating wave negative half period, the switching device conducting that triangular wave rising edge and modulating wave intersection point are connected power supply negative terminal as this phase input constantly, and the triangular wave trailing edge turn-offs the moment with the modulating wave intersection point as the switching device that this phase input is connected power supply negative terminal.The control of each phase current break-make of other of motor similarly, but corresponding modulating wave must time interval of translation with respect to above-mentioned modulating wave, makes the phase difference of first-harmonic in two modulating waves equal electrical degree between this two-phase input just.
Adopt said method, electric current has kept the rudimentary subharmonic current of drafting reservation in advance in the motor, can make that the magnetic flux density amplitude greatly descends in the motor magnetic circuit.Keep former amplitude size if strengthen the maximum that the fundamental frequency electric current makes magnetic flux density in the motor magnetic circuit again, can improve the power output of motor.But this way only can limit at short notice, this is because the amplitude of the triple-frequency harmonics magnetic potential that unitary current produces is all lower, form three times certain rotating magnetic potentials, need three times bigger exciting currents, this certainly will strengthen excitation loss (however, this way greatly improves the margin of power and the overload capacity of motor, still highly significant), in order to overcome this defective, below provide the another kind scheme preferably of utilizing triple-frequency harmonics.
Its way as shown in Figure 5, motor windings 1 number of phases q is greater than 3 and be 3 odd-multiple, the end of three phase windings 1 that any input electrical degree mutual deviation is 120 ° connects altogether, connects the input of a triple-frequency harmonics winding 50 more respectively, these triple-frequency harmonics winding ends connect altogether.The triple-frequency harmonics winding distributes in motor, by forming the stator winding distribution (wherein p be the magnetic pole logarithm of winding 1) of 3p to magnetic pole, and when making triple-frequency harmonics winding 50 paths that any phase winding 1 is connected with it feed electric current, the center of the magnetic potential N utmost point that winding 1 produces in magnetic air gap, a S utmost point center that produces magnetic potential with triple-frequency harmonics winding 50 in magnetic air gap overlaps (as shown in Figure 6).The voltage of the input input of every phase winding 1 is the superposition of fundamental voltage and third harmonic voltage.
During the machine operation that constitutes for above-mentioned way, if apply the electromotive force that contains first-harmonic and triple-frequency harmonics in motor windings 1, because the end of three phase windings 1 that any input electrical degree mutual deviation is 120 ° connects altogether, triple harmonic current can not form the loop between motor windings 1, therefore the triple harmonic current triple-frequency harmonics winding 50 of must flowing through, produce the triple-frequency harmonics rotating magnetic potential, and the amplitude of the triple-frequency harmonics magnetic potential that triple-frequency harmonics winding unitary current produces is very high, according to motor electric potential balancing principle, the third harmonic excitation electric current can be very not big as can be known, because triple-frequency harmonics rotating magnetic potential and first-harmonic rotating magnetic potential are synchronous, and overlap with the trough of triple-frequency harmonics magnetic potential at fundamental magnetic potential peak value place, cancel each other, reduced the maximum of rotating magnetic potential.
Below providing one adopts mechanical mechanism to realize the embodiment that the variable-frequency AC induction motor harmonic wave utilizes as switching device.
As shown in Figure 7, by power distribution device 20 direct voltage is introduced the input of every phase winding of induction alternating current (AC) motor; Power distribution device 20 is made of rotor 30 and brush 8; Two conductions of peripheral surface distribution semi-rings 6 of rotor 30; Conduction semi-ring 6 is electrically connected with the conducting ring 9 at rotor 30 both ends respectively; Two conducting rings 9 contact with a brush 10 respectively; Two brushes 10 connect the both positive and negative polarity of DC power supply respectively; Has circumferential insulation gap 7 between two conduction semi-rings 6; Brush 8 connects the input of AC induction motor, and contacts with rotor 30 outer surfaces.
Obviously, be a similar square wave by above-mentioned mechanical device at the voltage waveform that the input of motor applies, comprise more harmonic wave composition.In addition, during motor frequency modulation, voltage should raise with increase frequency, when each conduction semi-ring 6 of above-mentioned mechanical device with when circumferentially insulation gap 7 is a fixed value to the central angle that open in the axle center of rotor 30 separately; DC power supply must have regulator, and the voltage that makes DC power supply increases with the input terminal voltage fundamental frequency of motor and raises.
Adopt following method, need not set up the DC power supply regulator, the voltage that just can realize DC power supply raises with the increase frequency of motor.As shown in Figure 8, each conduction semi-ring 6 and circumferential insulation gap 7 change along rotor 30 axial distribution width, and promptly the central angle that open in the axle center to rotor (30) changes vertically; Brush 8 axially can move with respect to rotor, and when regulating motor speed, rotor speed changes from low to high, and from the little big side shifting of a lateral width of conduction semi-ring width, vice versa by certain control device control for brush.
Below accompanying drawing is described:
Fig. 1 Fig. 2 is respectively three phase induction motor harmonic analysis figure and 15 phase induction motor harmonic analysis figure, circle symbol among the figure shown in 11, the synthetic rotating magnetic potential of harmonic current that representative is shown by the tabulation at the harmonic magnetic potential of its place line display and place rotates with ω speed.And the triangle symbol shown in 12, it is identical to represent above-mentioned rotating magnetic potential and ω to turn to, but asynchronous.Square symbol shown in 13 is represented above-mentioned rotating magnetic potential and ω switched in opposite.On behalf of above-mentioned rotating magnetic potential, the lines shown in 14 do not exist.Fig. 3 is a general structure schematic diagram of the present invention, and 1 is the winding of AC induction motor among the figure, the 2, the 3rd, and switching device, the 4th, last fly-wheel diode, the 5th, following fly-wheel diode.Fig. 4 is that the range winding electric machine adopts the method for modulation signal to realize Current Control modulation principle figure, and 40 is modulating waves among the figure, the 41st, and triangular carrier.Fig. 5 is a kind of better scheme schematic diagram that utilizes triple-frequency harmonics, and 50 is triple-frequency harmonics windings among the figure.Fig. 6 is the location diagram that winding 1 and triple-frequency harmonics winding 50 produce magnetic potential separately among Fig. 5.Fig. 7 adopts mechanical mechanism to realize the example structure figure that the variable-frequency AC induction motor harmonic wave utilizes as switching device, and 6 is conduction semi-rings among the figure, and the 7th, insulation gap, the 8th, brush, the 20th, power distribution device, the 30th, rotor.Fig. 8 is that Fig. 7 rotor 30 launches plane graph, the 9th, conducting ring, the 10th, brush.
The variable-frequency AC induction motor harmonic wave that the present invention proposes utilizes scheme can improve the motor traveling comfort, reduce vibrations and noise, improve the operational efficiency of motor, improve motor permeability magnetic material utilance, improve the power of motor, reduce the semiconductor switch device switching frequency, thereby reduced the pipe consumption of semiconductor switch device, having prolonged the control system life-span, be particularly suitable for the high power AC induction motor, is a kind of improvement project of desirable variable-frequency AC induction motor.
Claims (6)
1, a kind ofly realizes that by induction alternating current (AC) motor and frequency-converting speed-governing control system thereof the variable-frequency AC induction motor harmonic wave utilizes scheme, be primarily characterized in that: the number of phases q of induction alternating current (AC) motor is greater than 3, the input of every phase winding (1) connects the positive pole and the negative pole of DC power supply respectively by two switching devices (2), (3); Switching device (2), (3) can be electronic switching devices, can also be the switching devices that certain mechanical mechanism constitutes; The input of every phase winding also connects the positive pole of fly-wheel diode (4) and the negative pole of following fly-wheel diode (5), and the negative pole of the positive pole of last fly-wheel diode (4) and following fly-wheel diode (5) is connected respectively to the negative pole and the positive pole of DC power supply again; Any two-phase is flowed into the phase difference of input fundamental current,, equate with electrical degree folded between the input of this two-phase by switching device control; The electric current that flows into every phase winding can comprise rudimentary time harmonic current, particularly triple harmonic current by switching device control; The terminal available following several method of each phase winding connects: (1) all connects altogether, and (2) are divided into some groups, and each group connects altogether, and (3) are divided into some groups, and each group connects altogether, connects end altogether and is connected with other winding.
2, utilize scheme according to right 1 described variable-frequency AC induction motor harmonic wave, be primarily characterized in that: get modulating wave (40) and have similar shape with motor first-harmonic rotating magnetic potential and the rotating magnetic potential that the rudimentary subharmonic rotating magnetic potential of intending keeping synthesizes, make it and a triangular carrier (41) compare, during the positive half cycle of modulating wave, triangular wave trailing edge and modulating wave intersection point as motor wherein a phase input be connected power positive end the switching device conducting constantly, and the triangular wave rising edge turn-offs the moment with the modulating wave intersection point as the switching device that this phase input is connected power positive end; During the modulating wave negative half period, the switching device conducting that triangular wave rising edge and modulating wave intersection point are connected power supply negative terminal as this phase input constantly, and the triangular wave trailing edge turn-offs the moment with the modulating wave intersection point as the switching device that this phase input is connected power supply negative terminal; The control of each phase current break-make of other of motor similarly, but corresponding modulating wave must time interval of translation with respect to above-mentioned modulating wave, makes the phase difference of first-harmonic in two modulating waves equal electrical degree between this two-phase input just.
3, utilize scheme according to right 1 described variable-frequency AC induction motor harmonic wave, be primarily characterized in that: motor windings (1) number of phases q is greater than 3 and be 3 odd-multiple, the end of three phase windings (1) that any input electrical degree mutual deviation is 120 ° connects altogether, the input that connects a triple-frequency harmonics winding (50) more respectively, these triple-frequency harmonics winding ends connect altogether; The triple-frequency harmonics winding distributes in motor, by forming the stator winding distribution (wherein p be the magnetic pole logarithm of winding (1)) of 3p to magnetic pole, and when making triple-frequency harmonics winding (50) path that any phase winding (1) is connected with it feed electric current, the center of the magnetic potential N utmost point that winding (1) produces in magnetic air gap, a S utmost point center that produces magnetic potential with triple-frequency harmonics winding (50) in magnetic air gap overlaps; The voltage of the input input of every phase winding 1 is the superposition of fundamental voltage and third harmonic voltage.
4, utilize scheme according to right 1 described variable-frequency AC induction motor harmonic wave, be primarily characterized in that: adopt mechanical mechanism to realize that as switching device the scheme of variable-frequency AC induction motor harmonic wave utilization is direct voltage to be introduced the input of every phase winding of induction alternating current (AC) motor by power distribution device (20); Power distribution device (20) is made of rotor (30) and brush (8); Two conductions of peripheral surface distribution semi-rings (6) of rotor (30); Conduction semi-ring (6) respectively and the conducting ring (9) at rotor (30) both ends be electrically connected; Two conducting rings (9) contact with a brush (10) respectively; Two brushes (10) connect the both positive and negative polarity of DC power supply respectively; Has circumferential insulation gap (7) between two conduction semi-rings (6); Brush (8) connects the input of AC induction motor, and contacts with rotor (30) outer surface.
5, utilize scheme according to right 4 described variable-frequency AC induction motor harmonic waves, be primarily characterized in that: each conduction semi-ring (6) of above-mentioned mechanical device and circumferential insulation gap (7) are fixed values to the central angle that open in the axle center of rotor (30) separately; DC power supply increases regulator, and the voltage of regulating DC power supply increases with the input terminal voltage fundamental frequency of motor and raises.
6, utilize scheme according to right 4 described variable-frequency AC induction motor harmonic waves, be primarily characterized in that: each conduction semi-ring (6) of above-mentioned mechanical device and circumferential insulation gap (7) change along rotor (30) axial distribution width, and promptly the central angle that open in the axle center to rotor (30) changes vertically; Brush (8) axially can move with respect to rotor, and when regulating motor speed, rotor speed changes from low to high, and from the little big side shifting of a lateral width of conduction semi-ring width, vice versa by certain control device control for brush.
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CN114128129A (en) * | 2019-09-02 | 2022-03-01 | 东芝三菱电机产业***株式会社 | Power conversion device and motor drive system |
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CN114128129A (en) * | 2019-09-02 | 2022-03-01 | 东芝三菱电机产业***株式会社 | Power conversion device and motor drive system |
CN114128129B (en) * | 2019-09-02 | 2024-04-09 | 东芝三菱电机产业***株式会社 | Power conversion device and motor drive system |
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