JP6562955B2 - Harmonic generator - Google Patents

Description

  Embodiments described herein relate generally to a harmonic generator that is additionally connected to a motor that is fed from a power main line connected to a power transformer.

  In general, induction motors are widely used as power sources for various facilities. In this type of electric motor, a power supply voltage is supplied from a main power line to a primary winding provided on a stator to generate a rotating magnetic field, thereby generating a rotating torque in the rotor. In this case, a harmonic voltage is generated due to the structure of the stator and the rotor. This harmonic voltage reduces the operating efficiency of the motor and causes a temperature rise.

  Therefore, various proposals have been made to reduce this harmonic. One proposal is that a current of a predetermined harmonic frequency is generated in phase with the power supply voltage supplied from the power main line, and a negative harmonic order of minus 1 serving as a braking force for the rotor is approximately 90 times higher than the power supply voltage. A reactance circuit that generates a harmonic voltage with a delayed phase is used (see Patent Document 1).

  In this proposal, it is necessary to create harmonics of a specific order according to the number of slots of the stator of the motor connected to the power equipment, so the motor structure (total number of slots and pole pairs for accommodating the stator coils) Different orders of harmonics are required depending on.

  And it is necessary to make the amplitude of those harmonics into an optimal value. However, if these necessary harmonics are simply synthesized, the amplitudes of the synthesized harmonics may affect each other and deviate from the originally required harmonics.

  The present invention has been made in view of such points, and improves the operating efficiency of the motor by separately creating harmonics for erasing with appropriately set frequencies and amplitude values and temporally synthesizing them. Provided is a harmonic generator capable of performing

JP 2008-295203 A

  The problem to be solved by the present invention is to provide a harmonic generator that can further improve the operating efficiency of the motor on the power trunk side that feeds the motor without altering the motor connected to the power trunk. It is in.

  A harmonic generation device according to an embodiment of the present invention is a harmonic generation device that is additionally connected to an electric motor that is supplied with alternating current from a power trunk line that is connected to a power transformer. Harmonic voltage generated by harmonic rotating magnetic flux generated between the stator and the rotor based on the ratio (Z1 / P) of the total number of slots (Z1) and the number of pole pairs (P) accommodated in the stator coil Among them, the order of {(Z1 / P) -1} is a harmonic generator that generates a harmonic voltage having the same order as the harmonic voltage and having an opposite phase as a braking force for the rotor. The harmonic generation device is characterized in that the erasing harmonic having the frequency and amplitude of a predetermined harmonic corresponding to {(Z1 / P) -1} of the electric motor is temporally switched and output. To do.

  According to the above configuration, since the harmonic voltage that generates the rotating magnetic flux that cancels the rotating magnetic flux serving as the braking force is applied to each type of electric motor, the operating efficiency of the electric motor is improved and the power saving effect is obtained. Can do.

It is an equivalent circuit diagram which shows the electric power installation containing the harmonic generator which concerns on one Embodiment of this invention. FIG. 2 is an equivalent circuit diagram in which a part of the equivalent circuit shown in FIG. 1 is rewritten. It is a figure which shows the relationship between the stator and rotor of an electric motor used in the harmonic generator which concerns on embodiment of this invention, (a) shows those structures, (b) shows the generated magnetic flux between them. Yes. It is a vector diagram for demonstrating the principle of operation of embodiment of this invention. It is a block diagram which shows an example of the harmonic current generator used for one Embodiment of this invention. FIG. 6 is a circuit diagram showing another example of part of the harmonic current generator shown in FIG. 5. It is a figure which shows the relationship between a harmonic generator, a harmonic current generator, and each electric motor in electric power equipment. It is a wave form diagram for demonstrating operation | movement of the harmonic current generator of one Embodiment of this invention shown in FIG. FIG. 2 is an equivalent circuit diagram for explaining an induced voltage of a fundamental wave generated in a rotor portion of the electric motor shown in FIG. 1. It is an equivalent circuit diagram explaining the harmonic voltage which arises in the rotor part of the electric motor shown in FIG. It is a characteristic view which shows the relationship between the rotational speed of the electric motor used for embodiment of this invention, the input electric power to a secondary winding, and a slip.

<Simple explanation of the principle of the present invention>
Prior to the description of the embodiments, the principle of the present invention will be briefly described.

  As described above, the present inventor has {(Z1 / P) -1} order rotational magnetic flux that serves as a braking force during operation of the electric motor connected to the main power line, as shown in Patent Document 1 described above. It has been found that it is sufficient to generate a harmonic voltage that generates a rotating magnetic flux that cancels out the.

  Therefore, unnecessary power consumption is reduced by creating erasing harmonics having a predetermined amplitude at specific harmonic frequencies corresponding to various electric motors, synthesizing them and supplying them to the electric motor. Here, the various electric motors refer to electric motors having different motor structures (ratio of the total number of slots for accommodating the stator coils and the number of pole pairs).

  The connection relationship between the power trunk line, the harmonic generator 13 of the embodiment of the present invention, and each type of electric motor is shown in FIG. This will be described in detail later.

  However, if the predetermined harmonics for erasing are synthesized, mutual interference will occur between those harmonics, resulting in deviation from the harmonics that require the predetermined frequency and amplitude. It was relatively difficult to adjust.

  In the present invention, the necessary erasing harmonics are individually created as described above to obtain appropriate harmonics, which are switched over in time and supplied to the connected motor.

  In this way, a plurality of harmonics are effectively supplied to various electric motors after a predetermined time. Moreover, the erasing harmonics can be easily created individually by a computer.

<Description of Embodiment>
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a relationship among a power transformer 11, a power trunk line 12, a harmonic generator 13, and an electric motor 14, for example, an induction motor, which constitute electric power equipment. These are shown by an equivalent circuit. The electric motor 14 means, for example, one type of electric motor among the plural types of electric motors shown in FIG.

  The harmonic generator 13 includes a reactance circuit 15 and a harmonic current generator 16. The harmonic current generator 16 is provided in the vicinity of the power transformer 11 as shown in the figure, or is connected in the vicinity of the input terminal of the electric motor 14 connected to the end of the power main line (also referred to as a low-voltage main line) 12.

  A power trunk line (100V, 200V, 400V, etc.) 12 is led out from both ends of the secondary winding of the power transformer 11. A power supply voltage V1 is generated between both ends of the secondary winding of the power transformer 11. Further, as shown in FIG. 2, the winding resistance Rt of the power transformer 11 and the leakage reactance + jνXt of the winding are present on the secondary winding side, and the reactance circuit 15 described above is configured.

  In addition, between the power main lines 12, harmonics that are sources of harmonic current (continuous wave current or pulse current) Iν (pls) including ν-order (11th, 17th, 23rd, etc.) harmonics. A current generator 16 is connected. The harmonic current Iν (pls) flows to the power transformer 11 side having a low impedance.

  The equivalent circuit of the power transformer 11 and the reactance circuit 15 can be rewritten as shown in FIG. In FIG. 2, the primary side leakage reactance 11-1 of the power transformer 11 is significantly smaller than the reactance 11-e of the excitation circuit of the power transformer 11, so the primary side leakage reactance 11-1 is short-circuited. It becomes the same as that.

  The impedance of the reactance circuit 15 is assumed to be Zν (pall). In the reactance circuit 15, the harmonic power source voltage Vν (pls) is generated by the harmonic current Iν (pls) from the harmonic current generator 16 flowing in the illustrated direction. That is, the harmonic current generator 16 serves as a current source for supplying a ν-order harmonic current Iν (pls) for generating the harmonic power supply voltage Vν (pls).

  Note that (slot) indicates a component originally generated in the electric motor, and (pall) (pls) indicates a component generated by the harmonic generator according to the embodiment of the present invention.

  Returning to FIG. 1, the electric motor 14 connected to the power trunk line 12 has a stator 14-1 portion and a rotor 14-2 portion. The stator 14-1 of the electric motor 14 is provided with a primary winding w1, and the rotor 14-2 is provided with a secondary winding w2. The primary winding w1 of the stator 14-1 is connected to the power trunk line 12 via a line reactance component + jXl. The primary winding w1 itself has a resistance component r1 and a reactance component + jvx1.

  The secondary winding w2 has a resistance component r2 ', a reactance component + jx2', and a resistance r (mk) = (1-Sν) r2 '/ Sν corresponding to a mechanical load.

  Here, when a substantially fundamental power supply voltage V1 is applied from the power main line 12 to an input terminal (not shown) of the motor 14, the primary winding w1 provided on the stator 14-1 of the motor 14 is connected to the input terminal V1 shown in FIG. As shown, a fundamental wave excitation current I (0) (1) that is 90 ° behind the fundamental wave voltage V1 of the power supply flows.

  Further, between the stator 14-1 and the rotor 14-2, the rotating magnetic flux φ1 having the same phase as the exciting current I (0) (1) is proportional to the exciting current I (0) (1). Will occur. Then, a counter electromotive force E1 is generated that is 90 ° behind the rotating magnetic flux φ1 (180 ° behind the power supply voltage V1). In addition, a voltage E1 'is induced in the secondary winding w2 of the rotor 14-2 in proportion to the voltage E1.

  Slots for accommodating the primary winding w1 are formed in the stator 14-1 of the electric motor, and the magnetic resistance is regularly distributed due to the slots. That is, as shown in FIG. 3A, the stator 14-1 has a slot 21 that accommodates a primary winding (also called a coil) w1 of three phases (u, v, w) as described above. Is formed.

  In the gap between the stator 14-1 and the rotor 14-2, there is a difference in magnetic resistance (permeance) between directly below the slot 21 housing the coil and directly below the stator core. Therefore, in addition to the rotating magnetic flux φ1 due to the fundamental wave, the ν-order harmonic rotating magnetic flux φν corresponding to the number of the slots 21 is generated.

Here, if the total number of slots of the stator 14-1 is Z1, the pole interval on the armature is τp, and the number of pole pairs is P, the permeance distribution wave k resulting from the slot 21 is expressed by the following equation (1). It is.

  In the above formula (1), kav is an average value of permeance.

In the fundamental wave rotating magnetic flux density shown in FIG. 3B, when B1 is B1sin (π / τ · x), the magnetic flux density wave Bν in the actual rotating state is expressed by the following equation (2).

From the above equation (2), the {(Z1 / P) +1)}-order harmonic rotating magnetic flux B {(Z1 / P) +1} 90 ° delayed from the fundamental waveform B1 and the fundamental waveform B1. It can be seen that a {(Z1 / P) -1} -order harmonic rotating magnetic flux B {(Z1 / P) -1} that is advanced by 90 ° is generated. (Hereinafter, {(Z1 / P) -1} and {(Z1 / P) +1} are also referred to as (Z1 / P-1) and (Z1 / P + 1)).
Since the magnetic flux is proportional to the area of the magnetic circuit, it is φ1∝B1, which means that φ (Z1 / P−1) -order and φ (Z1 / P + 1) -order rotating magnetic flux is generated.

  As is well known, the φ (Z1 / P + 1) -order magnetic flux rotates in the positive direction and 90 ° behind the fundamental wave rotating magnetic flux wave φ1. Further, the φ (Z1 / P−1) -order magnetic flux rotates in the opposite direction to the fundamental wave rotating magnetic flux wave φ1 and in a phase advanced by 90 °. Usually, 12, 18, and 24 slots are frequently used as the number of slots (Z1 / P) per pole of an electric motor. Therefore, as the (Z1 / P-1) order, 11, 17, and 23rd order reverse rotating magnetic flux density waves are generated, and as the (Z1 / P + 1) order, 13, 19, and 25th order rotating magnetic flux density waves are generated. To do.

  The harmonic voltage Vν (slot) is applied to the primary winding w1 of the stator 14-1 by the (Z1 / P + 1) th order and (Z1 / P-1) th order harmonic rotating magnetic flux φν (slot). However, a harmonic voltage Vν ′ (slot) is generated in the secondary winding w2 of the rotor 14-2.

  Among them, the (Z1 / P-1) -order, that is, the 11th, 17th, and 23rd harmonic voltages Vν ′ (slot) generate a rotating magnetic flux that serves as a braking force for the rotor 14-2. As a result, wasteful power is consumed. Therefore, it is necessary to reduce these harmonics. Hereinafter, the response to the (Z1 / P-1) order harmonic will be described.

  In the present invention, as shown in FIG. 1 and FIG. 2, a harmonic current generator 16 is connected to the power main line, and a constant ν-order harmonic current Iν (pls) has an impedance Zν (pall). It flows to the reactance circuit 15. As a result, a harmonic voltage Vν (pls) = Zν (pall) · Iν (pls) is generated and amplified. This harmonic voltage Vν (pls) generates a harmonic rotating magnetic flux φν (pls) having an opposite phase to the ν-order harmonic rotating magnetic flux φν (slot) caused by the slot 21 described above.

  As a result, the harmonic rotating magnetic flux φν (slot) is reduced, and the harmonic voltages Vν (slot) and Vν ′ (slot) generated by the harmonic rotating magnetic flux φν (slot) are reduced. As a result, it is possible to reduce the power that is wasted due to the harmonic voltage Vν ′ (slot).

  The relationship described above will be described below with reference to the vector diagram of FIG.

  FIG. 4 shows that the number of phases m is 3, the number of coils q per pole is 3 and the number of slots per pole pair is 2 mq, that is, (Z1 / P) is the 17th order in the 18 motors. The harmonics are shown.

  When the power supply voltage V1 is applied to the input terminal of the electric motor 14, a rotating magnetic flux φ1 delayed by 90 ° with respect to the fundamental wave voltage V1 of the power supply is generated between the stator 14-1 and the rotor 14-2. A counter electromotive force E1 is generated in the primary winding w1 of the stator 14-1 with a 90 ° delay relative to the rotating magnetic flux φ1 (a 180 ° delay with respect to the power supply voltage V1).

  In the gap between the stator 14-1 and the rotor 14-2, a ν-order harmonic rotating magnetic flux φν (slot) corresponding to the number of slots 21 that accommodate the coils is generated. This harmonic rotating magnetic flux φν (slot) is 90 ° ahead of the rotating magnetic flux φ1 by the fundamental wave.

  Further, a harmonic voltage Vν (slot) is generated in the primary winding w1 by the harmonic rotating magnetic flux φν (slot). The harmonic voltage Vν (slot) is advanced by 90 ° with respect to the harmonic rotating magnetic flux φν (slot).

  In contrast, the harmonic current generator 16 shown in FIG. 1 and FIG. 2 includes the ν-order harmonic current Iν (pls) in phase with the power supply voltage V1, including the leakage reactance + jνXt of the power transformer 11. The reactance circuit 15 is supplied in the direction shown in the drawing. The harmonic current Iν (pls) flows through the reactance circuit 15 described above, and a voltage drop due to the harmonic current occurs at both ends of the reactance circuit 15 due to the impedance Zν (pall). When the harmonic voltage is Vν (pls), Vν (pls) = − Zν (pall) · Iν (pls).

  Since the impedance Zν (pall) of the reactance circuit 15 includes the leakage reactance + jνXt of the power transformer 11 as described above, the harmonic voltage Vν (pls) generated by the flow of I17 (pls) is shown in FIG. Thus, the phase is delayed by 90 ° with respect to the power supply voltage V1.

  Here, when the harmonic current generator 16 is connected to the terminal of the power main line 12, the reactance of the reactance circuit 15 is the sum of the reactance Xt of the power transformer 11 and the reactance Xl of the power main line 12, Impedance Zν (pall) is obtained.

  When this harmonic voltage Vν (pls) is applied to the primary winding w1 of the motor 14, as shown in FIG. 1, the ν-order excitation current I (0) (ν, pls) is changed to the primary winding. It flows to w1. Since this exciting current I (0) (ν, pls) is delayed by 90 ° with respect to Vν (pls), the harmonic rotating magnetic flux φν (pls) in phase with the exciting current I (0) (ν, pls). Occurs as shown in FIG. That is, the harmonic rotating magnetic flux φν (pls) based on the harmonic current generator 16 is completely reversed with the phase angle θν (slot, pls) with respect to the harmonic rotating magnetic flux φν (slot) caused by the slot being 180 °. It becomes a phase.

  Therefore, the harmonic rotating magnetic flux φν (slot) caused by the slot decreases, and is induced in the harmonic voltage Vν (slot) generated by the harmonic rotating magnetic flux φν (slot) and thereby the secondary winding w2. The harmonic voltage Vν ′ (slot) decreases. As a result, it is possible to reduce the power that is wasted due to the harmonic voltage Vν ′ (slot).

  Here, the motor 14 fed from the power trunk line 12 is not limited to the above-described number of slots per pole pair, that is, (Z1 / P) is not only one type of motor having 18 but also the same power trunk line 12 (Z1 / P) is often used in combination with 12 or 24 motors. In other words, as described above, a plurality of types of motors having 12, 18, 24, and 30 slots per pole (Z1 / P) are frequently used for the motor 14.

  Therefore, the harmonic current generator 16 connected to the power trunk line 12 is a component that supplies a harmonic current that is a mixture of 11th, 17th, 23rd, and 29th harmonics that generate reverse rotational torque in the motor 14. Use.

  The harmonic current Iν (pls) that the harmonic current generator 16 flows is a continuous wave current or a pulse current. First, FIG. 5 shows a harmonic current generator 16 in which the current waveform of the harmonic current Iν (pls) generates 11th, 17th, 23rd, and 29th order continuous wave currents with respect to the basic power supply voltage V1. It explains using.

  FIG. 5 shows one phase. Since the actual power trunk line 12 is a three-phase system, the circuit for one phase shown in FIG. 5 is provided with three circuits corresponding to the input voltages of the phases u, v, and w constituting the three phases.

  As shown in FIG. 5, the harmonic current generator 16 includes a comparator 51 that changes an AC waveform into a rectangular wave, a harmonic generation unit 52 that generates a predetermined higher-order harmonic, and a phase of the generated higher-order harmonic. A phase adjustment unit 53 that adjusts the amplitude of the higher-order harmonics, a variable resistor unit 54 that changes the amplitude of the higher-order harmonics, a harmonic switching unit 55 that switches the higher-order harmonics that have their phases adjusted, and a switching time of the harmonic switching unit 55 The switching time control unit 55s that controls the output and the output unit 56 that outputs the switched higher-order harmonics.

  The comparator 51, the harmonic generation unit 52, the phase adjustment unit 53, the variable resistance unit 54, the harmonic switching unit 55, and the switching time control unit 55s are configured by a computer, for example, and are digitally caused by the slots in the motor. Generation of harmonics of harmonic magnetic flux (erasing harmonics), phase adjustment, amplitude adjustment, output harmonic switching, and the like are performed. The erasing harmonic having a specific frequency and amplitude is switched at predetermined time intervals and input to the output unit 56.

  The output unit 56 outputs a half-wave signal, but the erasing harmonics corresponding to each motor are continuously added to the following plural types of motors after a predetermined time. The operation will be specifically described later.

  An input voltage from each phase (for example, u phase), that is, an AC basic power supply voltage V1 of, for example, a commercial power supply is input to the input terminal a of the comparator 51. The input basic power supply voltage V1 is obtained by the comparator 51 as a rectangular wave having the same phase as the basic power supply voltage V1 or a waveform close thereto, and is output to the output terminal b.

  In the harmonic generation units 521, 522, 523, and 524, 11th, 17th, 23rd, and 29th continuous harmonics are generated, respectively. Each output of the harmonic generation unit is input to one of the input terminals of the phase adjustment units 531, 532, 533, and 534.

  On the other hand, the rectangular wave output from the output terminal b of the comparator 51 is input in parallel to the phase adjustment units 531, 532, 533, and 534 as a comparison output to the other input terminal.

  Output terminals of the phase adjustment units 531, 532, 533, and 534 are connected to input terminals of the variable resistance units 541, 542, 543, and 544. The amplitudes of the harmonics whose phases have been adjusted by the phase adjustment units 531, 532, 533, and 534 are adjusted by the variable resistance units 541, 542, 543, and 544. The output terminals of the variable resistance units 541, 542, 543, and 544 are connected to the input terminal of the harmonic switching unit 55. The harmonics whose amplitude has been adjusted by the variable resistance units 541, 542, 543, and 544 are switched by the harmonic switching unit 55.

  On the output side of the harmonic switching unit 55, an output unit 56 provided between lines u and v constituting one phase of the power trunk line 12 is connected. The output unit 56 includes power transistors or MOS type FETs (MOS type FETs are shown) 561 and 562 as final stage output elements connected in antiparallel between the lines u and v via diodes and resistors. Have.

  And the output terminal of the harmonic switching part 55 mentioned above is connected to those bases or gates via the bias circuits 563 and 564, respectively.

  As described above, the bias circuits 563 and 564 are provided at the bases or gates of the power transistors or the MOS type FETs 561 and 562, respectively, thereby functioning as an analog amplifier.

  In the output unit 56, the NPN MOSFET 561 conducts in the positive half cycle of the commercial AC voltage. On the other hand, in the negative half cycle of the commercial AC power supply voltage, the PNP MOSFET 562 conducts.

  A bias voltage is applied to these FETs 561 and 562 to cause a class B operation.

  The harmonic current generator 16 of the present embodiment is configured as described above.

  In the embodiment shown in FIG. 5, a half-wave output circuit is used for the output unit 56. This is because a transformer must be used to obtain the full-wave output, but the phase is adjusted in the phase adjustment unit 53 in the previous stage to prevent the phase from changing as much as possible. Usually, a phase error of about 5 degrees occurs due to the exciting current of the transformer.

  However, a full-wave output may be obtained using a transformer. The circuit configuration of the harmonic current generator 16 in that case may be configured as shown in FIG. That is, a transformer 565 is added to the circuit shown in FIG. 5, and the DC power supplies + VOO and −VOO are connected to the final stage output elements 561 and 562 via the transformer 565. The use of the output section having such a configuration has an advantage that a harmonic current can flow by applying a DC power supply voltage even in a half cycle in which the basic power supply voltage V1 is negative.

<Description of connection and operation of this embodiment>
Here, the connection relationship and operation of this embodiment will be described.

  Normally, a plurality of types of electric motors having different numbers of slots are connected to the power trunk line. Let P be the number of pole pairs of the motor and Z1 be the total number of slots in the stator of each motor. In the case of a three-phase power supply, (Z1 / P) is a multiple of 6, so this value is 12, 18, 24, 30 and so on. The harmonic generator of this embodiment is connected between a power trunk line and a plurality of types of electric motors.

  FIG. 7 shows a connection relationship between the plurality of types of electric motors and the harmonic generator of the present invention additionally connected between the electric motors and the power trunk line. That is, the harmonic generator 13 of this embodiment is connected to the power trunk line 12, and the harmonic generator 13 is connected to the motors 1412, 1418 a, 1418 b, 1424 a, 1424 b, 1430.

The harmonic generator 13 includes a harmonic current generator 16. The electric motor 1412 has a Z1 / P of 12, and the electric motors 1418a and 1418b have a Z1 / P of 18. Further, the motors 1412a and 1412b are of the type in which Z1 / P is 24, and the motor 143 is of the type in which Z1 / P is 30. Thus, a plurality of types of electric motors are connected to the output terminal of the harmonic generator 13. Therefore, in order to improve the operating efficiency of these electric motors, various electric motors are provided in the harmonic current generator 16 of the harmonic generator 13. It is necessary to simultaneously generate a plurality of order harmonic voltages in the leakage reactance of the connected transformer by flowing a plurality of order harmonic currents that generate reverse rotational torque corresponding to the above.

  The order of the harmonics in the reverse rotation direction for erasing (reverse harmonic order) ν is {(Z1 / P) −1}. In the case of a three-phase power source, 5, 11, 17, 23, 29, 35, 41, etc. are generally frequently used as the value of the inverse harmonic order ν. Therefore, in the harmonic current generator 16 shown in FIG. 5, the 11, 17, 23, and 29th-order continuous harmonics are created and phase-adjusted, and then the amplitude is adjusted and these harmonics are switched, and the half-waves are switched. The output is output from the output unit 56.

  Next, the operation of the harmonic current generator 16 shown in FIG. 5 will be described in an easy-to-understand manner using the waveform diagram of FIG. The waveform diagram shown in FIG. 8 basically shows the output waveform from the output unit 56.

  In the harmonic generation units 521, 522, 523, and 524, the above-described 11, 17, 23, and 29th-order harmonic continuous waves are generated. These harmonics are phase-adjusted by the phase adjusters 531, 532, 533, and 534. Thereafter, the amplitudes of the respective harmonics are adjusted by the variable resistance units 541, 542, 543, and 544, switched by the high frequency switching unit 55, and output from the output unit 56 as a half wave.

  A waveform 821a in FIG. 8 shows the upper half wave of the continuous wave waveform of the 11th harmonic created by the harmonic creating unit 521. The rising zero cross point of the 11th harmonic is adjusted in the direction of the double arrow 871 in the phase adjusting unit 531 so as to match the timing of the rising zero cross point of the alternating current 81. Therefore, the rising zero-cross point of the 11th harmonic coincides with the rising zero-cross point of the alternating current and becomes the time point of the arrow 881. The falling zero-cross point of the 11th harmonic can be matched in phase with the falling zero-cross point of the alternating current.

  A waveform 822a indicates the upper half wave of the continuous wave waveform of the 17th harmonic generated by the harmonic generator 522. The rising zero cross point of the 17th harmonic is adjusted in the direction of the double arrow 872 in the phase adjustment unit 532 so as to match the timing of the rising zero cross point of the alternating current 81 in the next cycle. Therefore, the rising zero-cross point of the 17th harmonic coincides with the rising zero-cross point of the alternating current, and becomes the time point of the arrow 882.

  Similarly, the waveform 823a shows the upper half wave of the continuous wave waveform of the 23rd harmonic generated by the harmonic generator 522. The rising zero cross point of the 23rd harmonic is adjusted in the direction of the double arrow 872 in the phase adjustment unit 533 so as to match the timing of the rising zero cross point of the alternating current 81 in the next cycle. Therefore, the rising zero-cross point of the 23rd harmonic coincides with the rising zero-cross point of the alternating current, and becomes the time indicated by the arrow 883.

  Although not shown in FIG. 8, the phase adjustment unit 534 similarly adjusts the phase of the 29th harmonic.

  The amplitude value is adjusted in the variable resistance unit 54. Specifically, the output of the 11th-order harmonic phase adjustment unit 531 is amplitude-adjusted by the variable resistance unit 541 to become an amplitude value I11 as shown in FIG.

  The output of the 17th-order harmonic phase adjustment unit 532 is amplitude-adjusted by the variable resistance unit 542 to become an amplitude value I17 as shown in FIG. Similarly, the amplitude of the output of the phase adjustment unit 533 for the 23rd harmonic is adjusted by the variable resistance unit 542 to become an amplitude value I23 as shown in FIG.

  Although not shown in FIG. 8, the amplitude of the output of the phase adjustment unit 534 is similarly adjusted by the variable resistance unit 544 for the 29th harmonic.

  The 11th-order, 17th-order, 23rd-order, and 29th-order harmonics subjected to the phase adjustment and the amplitude adjustment are switched by the harmonic switching unit 55 in almost one cycle of alternating current.

  This switching time is controlled for inspection by the switching time control unit 55s. This switching control time is usually longer than one AC cycle. The harmonics of the 11th, 17th, 23rd, and 29th harmonics that have undergone phase adjustment and amplitude adjustment are applied to the output unit 56.

  In the output unit 56, as shown in FIG. 8, each harmonic is made into a positive and negative half-wave waveform.

  The harmonic generated by the harmonic generating unit 52 is most preferably a sine wave. This is because other harmonic components are not included. Accordingly, the rectangular wave is not preferable because it includes other harmonic components. It is desirable that the waveform be as close to a sine wave as possible.

<Amplitude value of each required harmonic>
Here, the amplitude value of each harmonic necessary for eliminating the harmonic generated in the generated electric motor will be described.

  The magnitude of the harmonic rotating magnetic flux φν generated due to the slot of the electric motor is related to the geometric shape of the slot. Normally, the higher the number of slots, the smaller the harmonic rotating magnetic flux φν (slot).

  The harmonic voltage generated by the harmonic magnetic flux generated due to the slot of the motor is small, and its measurement is generally difficult.

  The inventor attempted to actually measure the harmonic voltage Eν in a main line that does not have any harmonic generator such as an inverter in the main power line.

The results are shown in Table 1. The upper order represents the harmonic order ν, and the lower stage represents the content ratio (%) of the harmonic voltage Eν to the fundamental wave.

  From this table, it has been found that the harmonic voltage Eν is inversely proportional to the harmonic order φν to the power of 1.2 to 1.5.

  It is understood that the voltage Eν (slot) generated in the motor winding by the harmonic rotating magnetic flux φν (slot) is proportional to the inverse harmonic order ν according to the above equation (2). From Table 1 above, it was found that the harmonic rotating magnetic flux φν (slot) is inversely proportional to the harmonic order ν of approximately 2.2. This is expressed by the following formula (3).

φν (slot) ∝1 / ν ^2.2 (3)
Since the harmonic electromotive force Eν (slot) ∝ν × φν (slot) generated in the motor,
Eν (slot) ∝ν × φν (slot) = ν × 1 / ν ^2.2 = 1 / ν ^1.2 (4)
It becomes.

Thus, the harmonic electromotive force Eν generated by the electric motor (slot) is inversely proportional to [nu ^1.2.

  Therefore, in the harmonic generator according to an embodiment of the present invention, a reverse rotation erasing harmonic electromotive force may be generated and applied in order to eliminate the harmonic electromotive force Eν (slot).

Erasing harmonic current Iν flowing in the harmonic current generator 16 shown in FIG 2 (pls) is made proportional to 1 / ν ^2.2. That is, the following expression (5) is obtained.

Iν (pls) ∝1 / ν ^2.2・ ・ ・ ・ ・ ・ (5)
Further, since the erasing harmonic electromotive force Vν (pls) is proportional to ν × Iν (pls), the following equation (6) is obtained.

Vν (pls) ∝1 / ν ^1.2・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ （6）
In other words, erasing the harmonic electromotive force Vν (pls) may be brought into inversely proportional to [nu ^1.2.

  For the amplitude of each harmonic, the amplitude ratio of each harmonic in Table 1 is used.

As for the current, the ratio of each harmonic current is as shown in Table 2 on the basis of the 17th harmonic current.

  Case 1 and Case 2 are the ratios of each harmonic current actually measured. In order to suppress the harmonic magnetic flux generated by the slot in the electric motor, Iν (pls) is passed through the harmonic current generator 16 shown in FIG. When the 17th harmonic is used as a reference, the optimal ratio is roughly 50% for the 23rd harmonic, 30% for the 29th harmonic, and 20% for the 35th harmonic.

  Moreover, it is preferable that the phase of each harmonic current that generates the counter-rotating magnetic field flowing through the power trunk line is substantially the same as the fundamental wave. The phase of the supply current of the 17th harmonic with respect to the fundamental wave is preferably within about ± 10 °.

<Explanation about slip>
Next, the power in the secondary winding w2 of the electric motor 14 described in FIG. 1 will be described in detail. First, the slip will be described.

  Of the rotating magnetic flux generated in the gap between the stator 14-1 and the rotor 14-2, the 11th, 17th, and 23rd components rotate in the opposite direction to the fundamental rotating magnetic flux as described above. . On the other hand, the 13th, 19th, and 25th components rotate in the positive direction. Here, the speed of the rotating magnetic flux of the ν order harmonic on the stator is Nν. The rotor rotates at the approximate fundamental wave synchronization speed N0. The slip Sν of the ν-order harmonic is obtained by the following equation (7).

Sν = (Nν−N0) / Nν (7)
In the case of 11th, 17th, and 23rd order reverse rotating magnetic fluxes, substituting -1/11, -1/17, -1/23 for Nv in equation (7) gives +12, +18, +24 as the value of Sv. Is obtained.

In this case, an equivalent circuit of the rotor 14-2 is shown in FIG. Since the input resistance is indicated by r ₂ ′ / Sν and is a positive value, harmonic power of this order is input from the power source to the rotor.

Further, an equivalent resistance r _mk corresponding to the mechanical axis output is shown in FIG. 10, and when each Sν is substituted, it becomes a negative value. That is, the electric motor 14 operates as a brake against this harmonic component. Therefore, in the rotor 14-2, the harmonic power generating the reverse rotating magnetic flux is regenerated from the shaft to the rotor and consumed by the secondary winding w2.

  In the case of 13th order, 19th order, and 25th order positive rotating magnetic fluxes, the slip Sν has negative values of −12, −18, −24 from the equation (7).

In this case, an equivalent circuit of the rotor 14-2 is shown in FIG. 9, and the input resistance r ₂ ′ / Sν is a negative value. The harmonic power of this order is not input from the power source to the rotor but is reflected to the power source side. Further, the equivalent resistance r _mk corresponding to the mechanical shaft output is shown in FIG. 10 and takes a negative value. Therefore, in the rotor 14-2, the harmonic power generating the positive rotating magnetic flux is regenerated from the shaft to the commercial power supply side via the rotor.

  The electric power by the fundamental wave in the secondary winding w2 of the electric motor 14 will be considered. FIG. 9 is an equivalent circuit when the fundamental voltage E1 'is induced in the secondary winding w2 in the rotor 14-2 portion of the electric motor 14 shown in FIG.

From FIG. 9, when the secondary input power P1 ′ of the fundamental wave is S1, and the slip is S1, the secondary input power P1 ′ is obtained by the following equation (8).

  Here, as an example of a 5.5 kw motor, assuming that r2 = 0.3Ω, x2 = 0.3Ω, and S1 = 0.04, P1 ′ is expressed by the following equation (9) from equation (4).

P1 ′ = 0.04 (E1 ′) ² / (r2) (9)
Next, the harmonic voltage content rate and power consumption in the rotor 14-2 when a harmonic that generates reverse rotating magnetic flux is applied will be described.

FIG. 10 shows an equivalent circuit of the secondary winding w2 when the harmonic voltage Vν ′ (slot) is induced in the secondary winding w2 for the rotor 14-2 portion of the electric motor 14 shown in FIG. ing. If the content of the ν-order harmonic voltage Vν ′ with respect to the fundamental wave voltage E1 ′ in the secondary winding w2 is Kν, Kν is expressed by Kν = Vν ′ / E1 ′. When the harmonic input power to the secondary winding w2 is Pν ′, the following equation (10) is obtained from FIG.

  Here, when ν = 17, Sν = + 18 from the above-described equation (3). In the 5.5 kw electric motor, as described above, r2 = 0.3Ω and x2 = 0.3Ω.

  Here, in the rotor secondary circuit, it is superimposed on a relatively large magnetic flux due to the slip current of the fundamental wave. The harmonics act in the saturation region of the BH curve due to the characteristics of the BH curve of the iron core. Therefore, the permeability at the harmonic is smaller than that at the fundamental wave.

  Therefore, if it is 1/5 with respect to X2 = 0.3Ω of the fundamental wave, it becomes X2 = (1/5) × 0.5Ω, and if these are substituted into the equation (10), the 17th harmonic input power P17 ′. Becomes the following equation (11).

P17 ′ = 2.722Kν (E1 ′) ² / (r2 ′) (11)
Here, it is the synchronous watt when the P17′-order harmonic magnetic field rotates at N0 / ν.

  Actually, since the rotor rotates at the synchronization speed N0, when converted into the synchronization speed, the actual harmonic power P17 'in the rotor secondary circuit is multiplied by ν, and the following equation (12) is obtained.

P17 ′ = 2.722νKν (E1 ′) ² / (r2 ′) (12)
Substituting Kν = 0.0086% into the above equation (12) and calculating P17 ′ from the relationship with the above equation (9), P17 ′ = 0.1P1 ′. That is, when the content of the 17th harmonic voltage is 0.0086%, 10% of the fundamental wave is consumed by the resistance of the secondary winding w2.

  Therefore, in this embodiment, as described with reference to FIG. 4, the harmonic current Iν (pls) from the harmonic current generator 16 is applied to the ν-order harmonic rotating magnetic flux φν (slot) caused by the slot. ) To generate a harmonic rotating magnetic flux φν (pls) having an opposite phase based on the ν-order harmonic voltage Vν (pls) generated in the reactance circuit 15.

  Then, the harmonic rotating magnetic flux φν (slot) generated due to the slot is reduced by the harmonic rotating magnetic flux φν (pls) having an opposite phase. As the harmonic rotating magnetic flux φν (slot) is reduced, the harmonic voltage Vν (slot) and thereby the harmonic voltage Vν ′ (slot) induced in the secondary winding w2 are reduced. As a result, the power consumed in the secondary winding w2 can be reduced by the harmonic voltage Vν ′ (slot).

  Here, as described above, of the harmonic power flowing into the secondary winding, the 11th, 17th, and 23rd harmonic power is consumed by the secondary winding w2, and the 13th, 19th, 25th, It has been explained that the next harmonic power is regenerated on the power supply side.

  Therefore, normally, the power obtained by adding the harmonic power and the fundamental mechanical axis output power is the input power of the motor 14.

  In the above-described embodiment, the harmonic generator 13 described in FIG. 1 is provided in the power trunk line 12 derived from the power transformer 11 to configure the power saving facility, and the harmonic power component is reduced. Input power to the electric motor 14 fed from the main power line 12 is reduced.

  FIG. 11 is a characteristic diagram showing the relationship of the input power to the secondary winding w2 of the motor 14 with respect to the rotation speed or slip of the motor. The characteristic indicated by the curve a before the power-saving facility is turned on is shifted to the characteristic indicated by the curve b after the power-saving facility is turned on. Therefore, the slip of the motor decreases from Sa to Sb, and the input power to the motor 14 decreases.

<Explanation of reduced power consumption after a predetermined time>
FIG. 5 shows an example of its configuration, and its operation is described with reference to the waveform diagram shown in FIG. 8. In the harmonic generator of the present invention, the higher-order harmonics for generating each back electromotive force are individually separated. They are generated, switched in terms of time and output, and the amplitude value is changed and supplied from the output unit to each type of electric motor.

In FIG. 7, when only the 30 KW electric motor 1430 is operated, that is, when the 29th-order harmonic is generated as the counter electromotive force, an example of change in the daily power consumption and the maximum power data per hour is as follows: Table 3 shows.

  In Table 3, for each date, the power consumption per day of the motor, the maximum power per hour within the day when the power generator is not connected, and when the power generator is additionally connected It shows the maximum power per hour in one day.

  In general, an electric motor generally used automatically repeats operation start (on) and operation stop (off). Therefore, even if the harmonic generator 13 according to the embodiment of the present invention is additionally connected at a certain point in the motor, the motor starts and stops operation irregularly. It is difficult to pinpoint exactly whether the effect has occurred.

  The electric motors shown in Table 3 are electric motors operating at a constant shaft output power. From the change in power consumption shown in Table 3, it can be understood that the maximum power consumption per hour in one day has decreased from the ninth day after the power generation unit is additionally connected.

On the other hand, in FIG. 7, an example of changes in the maximum power consumption data when a plurality of motors, specifically, 10 KW motors, 10 units, 2 22 KW motors, and 2 30 KW motors are connected is shown in Table 4. Show.

  In Table 4, for each date, the daily power consumption of all motors, the maximum amount of power used per hour during the day when the power generator is not connected, and the power generator are additionally connected. The maximum power consumption per hour in one day is shown. Also in this case, the plurality of electric motors repeatedly start and stop operation independently of each other.

  Therefore, it is difficult to accurately indicate from which point the power saving effect by the power generation unit according to the embodiment of the present invention occurs. However, also in Table 4, it can be understood that the maximum power consumption per hour has been remarkably reduced from the eighth day after the power generation unit is additionally connected.

  Although other experiments were conducted under different conditions, it was found that it took about 2 to 10 days from the time when the harmonic generator was additionally connected until the power saving effect appeared in each motor. As described later, this is considered to be caused by the holding action by the iron core of the electric motor.

  In this way, by creating a predetermined high-order harmonic that generates back electromotive force according to each type of electric motor to be connected, and additionally connecting power equipment that outputs a harmonic adjusted to a predetermined amplitude value, By reducing the harmonics generated in each electric motor, it is possible to obtain a power saving effect.

  The inventor of the present application has a delay action and a holding action of a power saving effect when a weak harmonic voltage is applied to the terminal of the motor in order to suppress the rotating magnetic field generated due to the slot in the motor. I found.

  That is, it takes several days, at least 2 to 5 days from the time when a weak harmonic voltage is applied until the power saving effect appears, and after the effect appears, the harmonic generator of the present invention is stopped. However, it was found that the power saving effect was maintained for about 10 to 20 days.

  This is considered to be because a magnetic effect due to so-called hysteresis characteristics remains on the iron core of the magnetic circuit constituting the electric motor.

<Modifications and application examples of the present invention>
Although several embodiments of the present invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. In the above embodiment, the case where the present invention is applied to an induction motor has been described. However, the present invention is also applicable to a PM motor using a permanent magnet for the rotor.

  These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 11 ... Power transformer 12 ... Power trunk line 13 ... Harmonic generator 14, 1412, 1418a, 1418b, 1424a, 1424b, 1430 ... Electric motor 14-1 ... Stator 14-2 .... Rotor 15 ... Reactance circuit 16 ... Harmonic current generator 21 ... Slot

Claims (5)

A harmonic generator additionally connected to an electric motor fed with alternating current from a power trunk connected to a power transformer,
Harmonics generated between the stator and the rotor based on the ratio (Z1 / P) of the total number of slots (Z1) and the number of pole pairs (P) in the stator coil during operation of the motor Among the harmonic voltages generated by the rotating magnetic flux, the harmonic voltage having the same order as the harmonic voltage serving as the braking force and the opposite phase with respect to the harmonic voltage serving as the braking force for the rotor. A harmonic generator to generate,
The harmonic generator is
A harmonic generator characterized in that a erasing harmonic having a frequency and an amplitude of a predetermined harmonic corresponding to {(Z1 / P) -1} of this electric motor is switched over in time and output. A harmonic current generator that generates a harmonic current of the order based on the number of slots in phase with the power supply voltage supplied from the power trunk line;
Provided in the power trunk line, having an impedance including leakage reactance of the power transformer, and having the same order as the harmonic voltage serving as a braking force for the rotor due to the harmonic current flowing, is approximately the power supply voltage. The harmonic generation device according to claim 1, further comprising a reactance circuit that generates a harmonic voltage delayed by 90 °. The harmonic current generator includes a harmonic current generating means for independently creating a harmonic current having a predetermined amplitude of a continuous wave of a plurality of harmonic orders corresponding to Z1 / P of the motor to be connected;
Phase adjusting means for combining the zero cross point of the harmonic current created by the harmonic current generating means with the zero cross point of the alternating current;
Switching means for temporally switching the phase-adjusted harmonic current;
Output means for outputting the harmonic current switched by the switching means to the motor;
The harmonic generator according to claim 2, wherein: The harmonic current generator includes a plurality of harmonic generation units that generate a continuous wave harmonic current corresponding to Z1 / P of the motor to be connected;
A plurality of phase adjustment units that match the phase of the zero cross points of the harmonics output from these harmonic generation units with the zero cross points of the alternating current applied by the power trunk line;
A plurality of amplitude adjusters for adjusting the amplitude of the harmonics output from these phase adjusters;
A harmonic switching unit that switches and outputs the harmonics adjusted in amplitude according to the alternating current;
An output unit that outputs the harmonics switched and output by the harmonic switching unit and supplies the harmonics; and
The harmonic generator according to claim 2, wherein:   5. The harmonic generator according to claim 4, wherein the output unit is constituted by a MOS FET.

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