JPS63144786A - Method for controlling commutatorless motor - Google Patents

Abstract

PURPOSE:To attenuate torque pulsation in an intermittent starting area, by advancing the angle of advance for a first converting means among two frequency-converting means, in a specified range, and by delaying a second converting means after the first converting means, to be 6-pulse-formed. CONSTITUTION:A synchronous motor 4 is controlling by the respective inverters 3-1, 3-2 of a first and a second frequency converters 31, 32. A plurality of position detecting sensors for the synchronous motor 4 are fixed on a sensor fitting table, and are arranged in the radial direction to be confronted with rotating position rings, and are turned ON/OFF every 180 deg. at the electrical angle, and are regulated to have the phase difference of every 60 deg. in order. Then, to set the angle P0 of lead for the gate signal of the first frequency converter 31, in a range of 0 deg.-60 deg., the sensor fitting table is advanced by 0 deg.-60 deg. at the electrical angle in the counter direction against the rotating direction of the synchronous motor 4, and gate signal to the second frequency converter 32 is delayed in the range 0 deg.-60 deg..

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a non-commutator motor control method, and particularly to a non-commutator motor control method suitable for controlling intermittent starting of a synchronous motor. .

(Prior Art) A system in which a synchronous motor is driven by a thyristor power converter is generally referred to as a commutatorless motor. Among them, a load commutation type non-commutator motor that uses the back electromotive force caused by the speed electromotive force of a synchronous motor to perform switching, that is, commutation, of the inverse converter of the Cyrisk power converter, that is, the Cyrisk inverter, has a configuration. It is widely used because it is simple and reliable.

In this type of non-commutated motor, when the rotational speed is near zero, the speed electromotive force of the synchronous motor is not sufficiently established, so that the si risk of the inverter cannot be commutated. For this reason, until the rotational speed reaches around 10% of the rated speed from zero, the forward converter of the Cyrisk power converter, that is, the DC output of the converter, is switched at every inverter switching timing, that is, in the 6-pulse method, the electric motor A so-called intermittent starting method is adopted in which the electric angle on the side is zeroed every 60 degrees, and in the 12-pulse method, every 30 degrees.

FIG. 8 is a block diagram showing a well-known example of a current-source six-pulse type non-commutator motor for driving a synchronous motor. As shown in the figure, commercial AC power supplies ER, E8. Converter 1 that inputs AC power from ET and outputs DC voltage
is thyristor RP.

It consists of a circuit in which RN, SP, SN, TP, and TN are connected in a three-phase bridge. DC reactor 2 smoothes current ripples in DC power from converter 1 . The inverter 3 which receives the direct current from the converter 1 and outputs the alternating current has a size IJ1. UP, UN, VP, VN
, WP and WN are connected in a three-phase bridge.

The synchronous motor 4 is driven by the converter 1 and the inverter 3, and has three-phase armature windings 4A: U-phase, V-phase, and W-phase. The position detector 5 mechanically detects the rotational position of the rotor 4B of the synchronous motor 4. Speed detector 6
detects the rotational speed of the synchronous motor 4 based on the signal from the position detector 5.

The electrical position detector 13 detects the set control angle β and rotation speed in the load commutation region. On the other hand, the switching circuit 14
The speed feedback signal is derived from the output of the speed detector 6 in the intermittent region and from the output of the electrical position detector 13 in the load commutation region. The speed reference setter 7 sends out a speed command signal for setting the rotational speed of the synchronous motor 4. The speed deviation amplifier 8 receives the speed command signal from the speed reference setting device 7,
The speed feedback signal from the speed detector 6 is compared and amplified.

Current detector 9 detects a current feedback signal, which is a signal proportional to the AC input current of converter 1 . The current deviation amplifier 10 compares and amplifies the output signal of the speed deviation amplifier 8 and the current feedback described in "2". α control circuit 11 controls the firing phase of converter 1 based on the output signal of current deviation amplifier 8 . [beta] control circuit]2 fires inverter 3 in a certain positional relationship with respect to the output signal of speed detector 6 or electrical position detector]3.

The operation of the commutatorless motor configured as above will be explained with reference to the time chart of FIG. 9. This figure 9(a) shows the voltage waveforms of the AC power supplies ER and E8°ET.
b) shows the firing timing of the thyristor of the converter 1, (C) shows the output voltage waveform of the inverter 3, and (d) shows the firing timing of the thyristor of the inverter 3.

Now, the input current of the converter 1 and the armature current of the synchronous motor having a proportional relationship thereto are controlled as follows.

First, the signal from the electrical position detector 13 is transferred to the switching circuit 14.
This speed feedback signal and the speed command signal from the speed reference setter 7 are compared at the input of the speed deviation amplifier 8. At this time, a speed deviation signal appears at the output of the speed deviation amplifier 8, and with this deviation signal as a reference, the current feedback signal of the current detector 9, which is proportional to the current of the synchronous motor 4, is matched by the current deviation amplifier 10. By giving the obtained deviation signal to the α phase control circuit 11, the control delay angle (commutation delay angle) α of the converter 1 is
to control the power given to the synchronous motor 4.

On the other hand, the β phase control circuit 12 inputs the current phase command signal from the electrical position detector 13 via the switching circuit 14,
A gate signal of a control advance angle (commutation advance angle) β as shown in FIGS. 9(c) and 9(d) is output. Therefore, the sirisks of inverter 3 are UP, VP, WP, UN, VN.
and WN are rendered conductive by the gate signal shown in FIG. 9(d). That is, the armature current of the synchronous motor 4 flows in the same phase as the gate signal.

In this manner, variable speed operation of the synchronous motor 4 is possible by controlling the magnitude and phase of the armature current.

By the way, in a DC type non-commutator motor, since the induced voltage of the synchronous motor 4 is not established at the time of starting, the voltage shown in Fig. 10 (c
) and (d), the thyristors of the inverter 3 are switched (commuted), and the thyristors WP, UP, and VP are switched.

It is necessary to intermittent the DC current flowing through WN, UN, and VN to switch the current-carrying phase. This operation is performed by the synchronous motor 4
This is done by converting a signal from a position detector 5 provided at a position detector 5 into a speed signal by a speed detector 6, and feeding back the converted speed signal as a speed feedback signal by a switching circuit 14.

Incidentally, FIG. 10 shows waveforms of various parts in the intermittent start region when the conventional control method is applied to the electric motor having the configuration shown in FIG. 8, and shows the case where the commutation advance angle β = 0''. The same figure (a) shows the induced voltage waveform of the synchronous motor 4, the same figure (b) shows the motor phase current, the same figure (c) shows the ignition timing of each cyrisk of Inno Ku Itoyo 3, the same figure (
d) shows the DC current waveform in detail.

As shown in Fig. 10(d), when a gate signal is given to each of the cyrisks of Inno(-3), the rising current of the DC current can be easily approximated by the following formula: O≦t≦11)
(1) Here, WC is the zero-crossing frequency of the open-loop transfer function in the current control system. On the other hand, when restricting the current, a constant negative voltage is applied to the inverter 3 with the control delay angle α of the converter being maximized. Also,
During intermittent starting, there is almost no back electromotive force in the motor, so this current changes almost linearly, and is approximated by the following formula...(2) Note that the zero current period T is the period when the current flowing through the thyristor is once zero. It is necessary to set the reverse bias period to be longer than about several tens to several hundreds of microseconds (turn-off time) determined by the thyristor element, which is the time from when the controllability is restored again.

Now, in recent years, as the capacity of non-commutated motors has increased, system configurations in which two or more thyristor power converters are used in combination have become widely adopted. For example, as shown in the block diagram of FIG.
In the two sets of frequency converters 31 and 32, converters 1 and 1-2 and inverters 3-1 and 3-2 are combined to form a multiplexed non-commutator motor, and a system with a phase difference of 30° is used. 3 A synchronous motor with two sets of Japanese-style machine windings,
This is a multi-phase non-commutator motor equipped with two sets of Cyrisk power converters that conduct 120° square wave currents with a 30° phase difference.

In this way, when starting a 12-pulse non-commutator motor consisting of two sets of thyristor power converters, the thyristor energization period of each set of inverters is set to 30 degrees, and each set is alternately energized using an alternating intermittent method. has been adopted. FIG. 12 is a time chart showing the alternating intermittent method when the conventional non-commutator motor control method is applied, and the commutation advance angle β. - In the case of 〇, the switching (commutation) of two sets of inverters is repeated every 30° and each set is alternately energized.
) is the phase current of the synchronous motor 4 due to each set of frequency converters'
Ul” Vl” Wl” U2” The waveforms of V2 and ■W2, the same figure (c) is the gate signal UPI of each set of thyristors.
, VPI, WPI, UF4°VF6. WF2. UNI,
VNI, WNI.

UN2. Represents VN2 and WN2.

(Problem to be Solved by the Invention) The switching timing of each sirisk in this alternating intermittent start is generally controlled by a 12-pulse method in which the commutation advance angle β0 is set to zero and the inverter is switched every 30'. there were. This is based on the theory that when the current is assumed to be a square wave, the torque generated by the synchronous motor is maximized.

However, as a result of actual characteristic analysis, the commutation lead angle β
. It was found that if the motor is controlled by setting it to zero, the pulsating component of the torque generated by the synchronous motor becomes large. Furthermore, it has been found that in the case of a control method in which the period of zero current increases, the number of pulsations in the generated torque increases. Furthermore, in the case of the two-pulse method, the frequency is high because the energization period is 30 degrees.

In other words, as the speed increases, the throttling period begins before the applied current reaches a constant value, so the applied current takes on a shape close to a triangular wave, and the pulsations of the generated torque also take on a more complicated waveform.

Generally, the primary resonance frequency of a mechanical system consisting of a synchronous motor and a driven machine often exists in the intermittent region.
If the torque pulsation in the intermittent region is large, it is undesirable because it may cause damage to mechanical parts and adverse effects on products due to resonance of the machine shaft system, and may even lead to the entire plant being stopped.

An object of the present invention is to provide a highly reliable non-commutator motor control method that eliminates the problems associated with torque pulsation in the prior art and reduces torque pulsation in the intermittent starting region of a non-commutator motor. It is on offer.

[Structure of the invention]

(Means for Solving the Problems) The non-commutator motor control method of the present invention converts AC power into DC power using a converter, and also converts the DC power into AC power using an inverter. In a non-commutator motor control method for controlling a synchronous motor by a frequency conversion means, in an intermittent starting region of the synchronous motor, a set commutation advance angle of the inverter of the first frequency conversion means is set in a range of 00 to 60°. and set the energization start angle of the inverter of the second frequency converting means to be 3 times higher than that of the inverter of the first frequency converting means.
The frequency converter is configured to delay by 0 degrees and set the current conduction period of each phase of each of the inverters of the first and second frequency converting means to 60 degrees.

(Function) Control advance angle β of the first frequency conversion means among the two frequency conversion means. is advanced in the range of 0° to 60°, the current application start angle of the second frequency converting means is delayed by 30° from the first converting means, and commutation of each inverter of each frequency converting means is performed every 60'. By making it a 6-pulse type,
The current in each phase of the synchronous motor becomes the sum of the currents in each frequency converting means, and the zero current period decreases, approaching a sine wave current.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a time chart showing the effect when a non-commutator motor control method according to an embodiment of the present invention is applied to a device configured as shown in FIG. 11. The figure (a) shows the induced voltage of the synchronous motor 4, and the figure (b) shows the induced voltage of the synchronous motor 4. The phase current of the synchronous motor 4 is controlled by each inverter 3-1, 3-2 of the second frequency converter 31, 32.
The waveform of U2''V2'IW2, the same figure (C) is the gate signal UPI of the thyrisk of each inverter 3-1゜3-2,
V.P.I.

WPI, UNI, VNI, WNI, UP2. VF6,W
F2. UN2. This shows the timing of VH2 and WN2, respectively.

On the other hand, FIG. 3 is an explanatory diagram related to the rotational position detection part of the synchronous electric machine 4, and FIG. ) is the same figure (a
) is a view taken along line X-X.

As shown in each of these figures, a plurality of position detection sensors 33 are fixed on a sensor mount 34 and arranged to face a position ring 35 that rotates as the synchronous motor 4 rotates in the radial direction. has been done. The sensor mount 34 is fixed to the main body (not shown) with a mounting bolt 36, and is configured to be movable and adjustable in the rotational direction of the synchronous motor 4.

Incidentally, the plurality of sensors 33 are marked with symbols AI, A2, . Bl, B2. Add CI and C2. on the other hand,
FIG. 3C is an explanatory diagram showing the output signals of each sensor 33, with symbols AI, A2. Bl.

B2. The output signals of the sensors 33 labeled with CI and C2 are adjusted so that they are turned on and off every 1800 electrical degrees and are sequentially transmitted with a phase difference of 60 degrees. FIG. 4(d) is an explanatory diagram of the position adjustment of the sensor 33, in which the output of the sensor 33 indicated by symbol B1 is β with respect to the UV line terminal voltage.

−〇°, β. =30° and β. -30° is shown. In addition, in this example, the symbol B1
The output of the sensor 33 with the symbol C1 is the rising point of the V-W line voltage, the output of the sensor 33 with the symbol A1 is the rising point of the V-W line voltage, and the output of the sensor 33 with the symbol A1 is the W-U line voltage. β when matching each rising point of . −
Since it is set to 0°, β of the gate signal of the first frequency converter 31. In order to arbitrarily set the frequency in the range of 0° to 60°, the sensor mounting base 34 is advanced by 0° to 60° in electrical angle in the opposite direction to the rotational direction of the synchronous motor 4, and the second frequency converter 32 The gate signal is delayed by a range of 0° to 60°.

As a result, the commutation of the inverters 3-1, 3-2 of the first and second frequency converters 31 and 32 is performed every 60 degrees, and as shown in FIG. The U-phase current is generated by the U-phase gate signal UP1. as shown in FIG. Due to UP2゜UNI and UN2, the induced voltage waveform EU of the synchronous motor 4 in the figure (a) is changed to the induced voltage waveform EU in the figure (b).
As shown in , the total current ■ of the current IU1 of the inverter 3-1 and the current I of the inverter 3-2. Therefore, the current is supplied in a form close to a sine wave current and with a reduced current zero period. Therefore, the pulsating component of the torque generated by the synchronous motor 4 can be significantly reduced.

Hereinafter, the effect when the commutatorless motor control method of this embodiment is applied will be explained.

The instantaneous input power P (t) and torque T (t) are the first
Each of the six periods A to F in the figure can be simply determined using the following formula. First, for period A, P (t) −E
-1-E -(I■1+Iv2)U 01
V + Ew bow w2 (4). Also, for period B, P (t) −EU・(IUl+IU2)−E (I
+1) ...(5)V VI
It becomes V2. For period C, P (t) = E ・ (IUI + ■U2) - Ev
I■2-EvEw1 (6). For period D, P (t) - EU (IU1 + IU2) - E (I +1) ... (7) w
wt w2 . For period F, P(t) child EUIυ2+Ev■■2 -E (I +1) ... (8
) w wt V2 . For period F, P(t)-Ev (Ivl+Iv2) -E (I +1) ... (9)W
It becomes WI W2. Here, E = E (wt−−βo) ・(10) U
Msin 6 E -E (wt 10--β.) -(12)W
M sin 2. On the other hand, the torque T (t) during the entire period is T
(t) −P (t) /Wm ・=(
13). Here, Wm is the mechanical angular velocity. Since the non-commutator motor is in two-phase energizing mode, ■Ul=I
'v□, IU2--IV2 holds true, and since all current waveforms i (t) are the same, (4) ~
Equation (9) can be rewritten as the following equation.

P (t) - (EU-2Ev+Ew)・i (t)・・
・(4°) P (t)-(2EU-2E■)・i (t)...(
5゛) P (t)-(2EU-Ev-E,)-i (t)...
・(6') P (t)-(2EU-2Ew) ・t (t)...
(7") P (t)-(EU+E■-2Ew)-i (t)...
・(8°) P (t)-(2Ev-2Ew)" i (t)...
(9') Therefore, equations (1), (2) and (4') to (
It is possible to obtain the instantaneous power from the equation (9°).

Considering that the mechanical angular velocity Wm is constant in a certain arbitrary minute period, (4
The waveform diagrams in FIGS. 4 and 5 show torque calculations performed according to equations (°) to (9°). FIG. 4 shows the intermittent starting high speed region, and the output current waveform of the thyristor power converter (inverter) is close to a square wave. On the other hand, FIG. 5 shows the intermittent starting high speed region, and the output current waveform approaches a triangular wave. However, the line currents flowing into the synchronous motor 4 are combined and have a waveform close to a sine wave current. For this reason, the generated torque also has a form in which pulsating torque is superimposed on constant acceleration torque.

In order to explain the effects of this embodiment, a comparison with the prior art will be made. FIGS. 13 and 14 show torque calculations performed using the prior art alternating intermittent starting method (β = 06) using a method similar to that described above. In other words, the first
FIG. 3 shows a torque waveform in a particularly low speed region during intermittent starting, and FIG. 14 shows a torque waveform in a high speed region during intermittent starting.

As is clear from each figure, the torque waveform in the conventional technology has a period of zero torque of one cycle (360' electrical angle).
Occurs 12 times during this period. This is because the inverter commutation of the Cyrisk power converter is performed every 30°. On the other hand, in the case of this embodiment, there is no zero torque period, and torque pulsation is reduced.

In order to quantify this, a harmonic analysis of the torque waveform was performed, and the results are shown in FIG. 6 and FIG. 15 for the case of this embodiment and the prior art, respectively. As is clear from these analytical characteristics, the harmonics of torque pulsation are as high as approximately 7 in the conventional technology.
While it was about 0%, according to this example, it was about 40%.
It can be seen that it is %.

Moreover, FIG. 7 shows the commutation advance angle β in the present invention. 0°, 30
These are the results of harmonic analysis of torque pulsation when set to
corresponds to the low speed region. As is clear from the figure, in this example, the torque pulsation is almost constant at any commutation advance angle.

As explained above, the commutation setting advance angle at startup is set in the range of 0° to 60° for one frequency converter, and the energization start angle of the other frequency converter is delayed by 30°, and the thyristor power converter By commutating the inverter every 60 degrees, torque pulsation in the intermittent starting region can be reduced. This can be easily achieved by adjusting the relationship between the line voltage and the output of the position detection terminal as shown in FIG.

As a result, various methods have been used to reduce torsional vibration due to torque pulsation in the intermittent starting region of non-commutated motors, such as (a) electrical reduction of pulsating torque, that is, increasing the number of si-risk converters; Use a multi-phase thyristor motor.

(b) Control the acceleration rate when passing the resonance point, that is, reduce the resonance magnification of torque.

(C) Adoption of a coupling with pulsating torque absorption characteristics.

(D) Enhancement of mechanical shaft strength.

(E) Mechanical system - movement of the next resonance frequency.

It is possible to suppress torque pulsation during intermittent operation of a non-commutated motor by simply changing the set position of the mechanical position detector installed in the synchronous motor, without considering special methods or countermeasures such as mechanical measures such as I can do it.

Furthermore, in the present invention, the commutation timing signal and speed feedback signal of the inverter of the thyristor frequency converter of the non-commutated motor are obtained from a mechanical position detector in the intermittent starting region, and are obtained by electrical position detection in the load commutation region. Even with a control method in which these switches are configured so as to be obtained from the rated speed and are switched at around 10% of the rated speed, it is possible to reduce torque ripple only during intermittent starting without depending on the load characteristics in the load commutation region. It becomes possible.

〔Effect of the invention〕

As described above, according to the present invention, torque pulsations during intermittent starting of a non-commutator motor can be suppressed, and the motor can be controlled to a highly reliable state with little mechanical vibration.

[Brief explanation of the drawing]

Fig. 1 is a time chart showing the effect when the non-commutator motor control method of the present invention is applied to the device having the configuration shown in Fig. 11, and Fig. 2 is a time chart showing the electrical phases of phase voltages and phase currents. , FIGS. 3(a) and 3(b) are a side view and an X-X arrow view showing the configuration of the position detector, respectively, FIG. 3(c),
(d) is the output signal of the position detector and β, respectively. Figures 4 and 5 are torque waveform diagrams of this embodiment, and Figures 6 and 7 (a) and (b) are frequency analysis results of torque pulsation according to the present invention, respectively. FIG. 8 is a schematic configuration diagram showing an example of a conventional non-commutator motor, FIG. 9 is a time chart for explaining the control operation of the non-commutator motor shown in FIG. 8, and FIG. 10 is a β . Figure 11 is a block diagram of a multiplexed commutatorless motor with two sets of Cyrisk power converters, and Figure 12 is a conventional 12-pulse type intermittent start. A time chart showing starting; FIGS. 13 and 14 are torque waveform diagrams according to the prior art, and −23= FIG. 15 is an explanatory diagram of harmonic analysis results according to the prior art. 1.14.1-2...Converter, 2...DC reactor, 3.3-1.3-2...Inverter, 4...
・Synchronous motor, 4A... Armature winding, 4B... Rotor, 5... Mechanical position detector, 6... Speed detector,
7...Speed reference setter, 8...Speed deviation amplifier, 9
...Current detector, 10...Current deviation amplifier, 11.
... α control circuit, 12 ... β control circuit, 13 ... electrical position detector, 14 ... switching circuit, 31 ... first
frequency converter, 32... second frequency converter. Applicant's agent Sato -Yoshi himself- Figure 2 OFF Choro Ii Closed 1 - Figure 6 Figure 7 (α) Figure 7 (b)

Claims (1)

[Claims] A non-commutator motor control method in which a synchronous motor is controlled by first and second frequency converting means that convert AC power into DC power using a converter and convert this DC power into AC power using an inverter. In the intermittent start region, the set commutation advance angle of the inverter of the first frequency conversion means is set in the range of 0° to 60°, and the energization start angle of the inverter of the second frequency conversion means is set to the range of 0° to 60°. Non-commutator motor control characterized in that each phase current conduction period of each inverter of the first and second frequency converting means is delayed by 30 degrees from the inverter of the first frequency converting means and is 60 degrees. Method.