JPS60121983A - Controlling method of synchronous motor - Google Patents

Abstract

PURPOSE:To reduce the capacity of a field input power source by reducing the radio of the rotating speed of a motor to the armature voltage at that time in a low speed rotating range lower than that of the rated rotating speed to the armature voltage at that time, thereby reducing the reactive power. CONSTITUTION:An exciting reference generator 25 inputs an output signal from a D/A converter 18, and an output is generated on the basis of a function of N/Va shown in the drawing. This output is compared with a signal of the armature voltage Va of a synchronous motor 15 detected by a voltage detector 23, and a voltage controller 24 controls a thyristor switch 22 so that the armature voltage Va is proportional to the rotating speed N as shown in the drawing on the basis of the compared result. Thus, the power source capacity of the field input power source 21 is reduced to largely improve the power factor of the power source.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Part of the Invention] The present invention relates to a method for controlling a synchronous motor in the case where a synchronous motor carrying a square torque load is operated at d1 variable speed using a frequency converter. [Technical background] Due to recent technological advances, various methods of variable speed operation of synchronous motors have been put into practical use, including methods that employ a forced commutation frequency converter and natural commutation (load commutation). There are methods that use a frequency conversion device. In addition, the field of application has expanded over the years, and it has come to be widely adopted from small and medium sized needles to medium and large sized needles. There are various load devices driven by these synchronous tKiJJ machines, but there are constant torque loads that require approximately constant torque regardless of the rotation speed, and constant torque loads that require approximately constant torque regardless of the rotation speed, and constant torque loads that require approximately constant torque regardless of the rotation speed. change 2
This was done by skillfully utilizing sea urchins, and the number of revolutions from 1 to
Pumps, blowers, fans, etc. whose negative torque changes with the square of the
Its features are utilized only in the contraction control system of synchronous motor WJ machines that drive loads such as compressors. First, the drive control system of synchronous motors will be explained. FIG. 5 shows an example of a conventional synchronous motor drive control system. Although there are various known systems depending on the type of frequency converter, FIG. 5 shows a DC type thyristor motor system called a thyristor motor system or a load commutation system. Since this detailed operating principle is already a well-known technique, the main points will be mainly explained with reference to FIG. 5 below. In this figure, 11 is the input exchange officer, source,
J2f'i rectifier, l:3 is current reactor, 14 is inverter, 15 is synchronous voltage! 11 machines, 151 is the field winding of the synchronous motor 15, 152 is the rotary rectifier, 15B is the induction frequency converter, 154i, t sensor, +6f′i speed reference setter, 17 is the speed controller, 18 is D/person converter,
19 is an α controller.

191 is a current detector, 21 is a Jrjβ controller, 21 is a field input power supply, 22 is a thyristor switch, 2:3 is a voltage detector, 24 is a voltage controller, 241 is a city, ? The AC' power of the zero-power AC power source 11, which is the IC1 detection output, is converted to DC power by the rectifier 12, 'rL, this'f! - The DC reactor 13 smoothes the power, and the inverter 14 converts it back into AC power of a different frequency, thereby operating the synchronous motor 15 at variable speed. At this time, the frequency of the AC power given to the synchronous motor 15 is set by the speed reference setting device 16, the rotational speed of the synchronous motor 15 is detected by the sensor 154, and this detection signal is converted into an analog signal by the A/A converter 18. Then, the speed controller 17 compares the speed with a speed reference and controls the rotation speed of the synchronous motor 5 in a closed loop. α controller 1 according to the output signal S2 of speed controller 17
The output DC power of the rectifier 12 is varied through the α controller 1 to variably control the power supplied to the synchronous motor a15.
Reference numeral 9 detects the input current of the rectifier 2 with a current detector 191, and controls the output current of the rectifier 12 in a closed loop.

On the other hand, the inverter 14 is controlled via the β control unit 20 by a detection signal obtained by detecting the rotational position of the field of the synchronous motor 15 by the sensor 154. At this time, the inverter 14 utilizes the back electromotive force of the synchronous motor 15 to perform load commutation (
The timing of this load commutation is controlled by the sensor 154 and the β controller 20. On the other hand, the magnetic flux of the synchronous motor 15 is generated by voltage-controlling the AC power of the field input power source 21 using the thyristor switch 22, and inputting this output to the induction frequency converter 15B.
It is generated by converting secondary side AC power into DC power with a rotary rectifier 152 and applying this to the field winding 151. At this time, the output signal (speed detection signal) of the D/A converter 18 and the voltage detection signal obtained by detecting the armature voltage of the synchronous W motor 15 by the voltage detector 23 are compared. The voltage controller 24 controls the voltage of the thyristor switch 22 based on the comparison result and the input current of the thyristor switch 22 detected by the eleventh current detector 241, thereby controlling the magnetic flux of the synchronous motor 15.

The characteristics of the drive control system for the synchronous motor 15 as described above will be explained with reference to FIGS. 6 and 7. In FIG. 6, the vertical axis shows the armature voltage Va (output voltage of the inverter 14) of the synchronous motor 15 and the load torque 1' of the synchronous motor [15], and the polar axis shows the rotational speed N of the synchronous motor U41i15.

As shown in this figure, when the load torque exhibits square torque characteristics, the conventional synchronous motor 15t/'i armature voltage Vn
It was common to control the ratio of the rotational speed N and the rotation speed N by one (two).The characteristics of the drive control system of the synchronous engine when controlling Va/N to a constant value in this way are explained in Fig. 7. do.

In FIG. 7, (R) is the armature current 1 of the synchronous motor 15.
a, (b) the field current If flowing through the field winding 151, and (C) the excitation input power Pf of the induction frequency converter 158.
1 and the excitation input voltage Bfl, and (d) the input power factor PFα of the Fi rectifier 12. For square torque load,
In Fig. 7, the armature current Ia is approximately proportional to the load torque T,
The field current If changes proportionally in the same way, but about 1/2 of the maximum rotational speed remains as the pace. Excitation input voltage Efl
Since the phase rotation direction of the excitation input voltage of the Tri induction frequency converter 158 and the rotation direction of the synchronous motor 15 are reversed, when the number of revolutions N is small, the maximum time is 1/2 of 100%. On the other hand, the excitation input power Pfl changes approximately in proportion to the square of the field current If. The input power factor PFα of the rectifier 12 changes approximately in proportion to the rotation speed N. This is shown in Figure 6 as Va/
This is because N is approximately constant.

[Problems with Background Art] The conventional drive control system for a synchronous motor that drives a square torque load, as described above with reference to FIGS. 5 to 7, often suffers from the first problem.

Generally, for a square torque load, the required power is the rotational speed N (7,)
Since it changes by the third power, the rotation speed of the synchronous motor 15 N<5
The period of operation at 50 to 80% of the rated value is relatively long. By the way, as is clear from FIG. 7(C) (when the rotation speed N of the two-synchronous electric model I5 is zero, the excitation input voltage Efl is maximum. Therefore, the excitation power supply capacity of the fat conduction frequency conversion Tachibana 158 at this time is 0 determined by the maximum value of the excitation input power Bfl and the current at the maximum of the excitation input power Pfl (when the rotation speed N is 100 degrees).As a result, the t source capacity of the field input power supply 21 is large. ``Purpose of the Invention'' The present invention was made in view of the above-mentioned shortcomings of the drive control system of the conventional synchronous force N aircraft. The purpose of this paper is to provide a control method for a synchronous motor that can reduce the rutting of the engine.

"Summary of the Invention" In order to achieve this object, the present invention provides a synchronous electric motor (a synchronous motor with a rotational speed N and its The ratio Va/N to the armature voltage Va at the time is the rated rotation speed N (100)
The ratio Va(
loo)/N(too).

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The system shown in FIG. C2 is characterized by the addition of an excitation reference generator 25. The excitation reference generator 25 inputs the output signal (speed detection signal) from the D/A converter 18, and generates a function having the relationship N-Va shown in FIG. 26 as a function of this input. It consists of a function generator. The system shown in Figure 5 (in the second case, the output signal of the D/A converter ■8)
Synchronous motor 1 detected by speed detection signal) and voltage detector
5C) The armature voltage Va is compared with the signal of the armature voltage Va, and as a result of this comparison, the voltage controller 24 performs two-closed loop control so that the t-state voltage Va is proportional to the rotational speed N as shown in FIG. 6 (2). By the way, the system C2 shown in FIG.
5 also generates an output for the function of N-Va shown in FIG. The output of the excitation reference generator 25 is compared with the signal of the voltage Va of the synchronous motor 15.Based on the result of this comparison, the sleeve pressure controller 24 is installed and the system shown in FIG. In exactly the same way, the root voltage Va is controlled to 1 in a closed loop. As a result, the armature voltage Va is controlled to the value of Va shown in FIG. The output signal of the synchronous motor 15
ti; jr! ! The operation of the excitation reference generator 25 will be explained using FIG. 2 since it is the same as the slave voltage Va.

Figure 2 shows the conventional figure 6 (two corresponding Va −N, '
It is an l'-N characteristic diagram. In this figure, load torque Tt/'i
T−N in FIG. 6 as a function of the rotational speed N of the synchronous motor 15
It changes in the same way as percentage. The field reference generator 25 and the b voltage are pattern-controlled so that Va-N is not constant over the entire range of the armature voltage Vaij and the rotational speed N. That is, in the example of Fig. 2, compared to Fig. 6, the rotational speed N is lower in the range of 0 to 25%, the voltage Va is lower, and Va/N is lower in the range of 25% to 75%. While maintaining the U armature voltage Va in a high direction, the U armature voltage Va is controlled to a substantially constant value in a high direction within a range of 75% to 100%. FIG. 3 shows the characteristics of the drive control system for the synchronous motor 15 when controlled in this manner. In FIG. 3, the characteristics of the conventional system shown in FIGS. 7(a) to (d) are shown by dotted lines, and the characteristics of the present invention are shown by solid lines. In this figure, the armature current 1a is roughly proportional to the cube of the rotation speed when the rotation speed N is 75% to 100 degrees, and when the rotation speed N is 25% to 75%, it is proportional to the negative torque T (
The load torque increases to 1 or more between 0 and 25%. The change in the field 'M161Elf is small in the range of 75% to 100 degrees to the rotation speed, and it is 25% to 1%.
In the range of 00%, the field current 1f increases as shown in FIG. 7(b). The excitation input power Pfl has a rotation speed N of 2b% to 10
It increases in the 0% range, but in this range the rotation speed is 100
% is the maximum and cannot be increased by 1 according to the present invention. On the other hand, excitation input pen pressure grl F1 rotation speed N is 0 to 25
In the range of %! The input power factor PFα of the zero rectifier 12, which decreases compared to FIG. 7(C), is almost the same as the maximum value in FIG. The range from 25 buns to 75 chips is much improved compared to FIG. 7(d).

As explained above, the excitation of the cotton frequency converter 15B is controlled by the source capacity excitation input Tlj and the maximum value of the pressure Efl is lower than that shown in FIG. Power supply 21 in 1! , the power supply capacity is also reduced, and the power supply power factor is also significantly improved. Such effects and advantages can be obtained because the present invention has two advantages.
This is because the multiplication torque is applied to the negative #I.

That is, in the range of rotation iN from 0 to 25%, as shown in FIG. 2, the armature voltage Va can be set lower than in FIG. 6 in the present invention because the load torque becomes small in this range. The torque generated by the synchronous motor 15 can also be reduced, and the above-mentioned advantages can be obtained only in the case of the squared torque negative f. As explained above, the present invention
The capacity of the synchronous motor 15, Th, and
The above effects and advantages can be obtained without increasing et or cost.

Characteristics according to another embodiment of the present invention are shown in FIG.

Compared to the conventional FIG. 6, which is another embodiment corresponding to FIG. It is not particularly limited as shown in FIG. 5, but can be set as shown in FIG. 7, and each range of the rotation speed N can be arbitrarily selected according to the normal operating range of the synchronous motor 15. Figures 2 and 4 above
As shown in the figure.

The present invention does not limit the magnitude of the armature'it (pressure Va) to the value of !'15' with respect to the rotational speed N. 1 motor 15, rated armature 17, pressure Va (100) and rated rotation speed N (1
00) (value of 100% point for anything 4)
It is clear that the above effect is diminished if the armature voltage Va is set to Va/N smaller than Va/N.00)/NBoo).

Further, the circuit configuration of the excitation reference generator 25 is not limited to a particular one, but is already known in the art of function generators capable of generating a desired output signal, and these function generators can be used as an excitation reference generator. It can be used as 25.

On the other hand, although a DC thyristor motor system is shown in FIG. 1 as a frequency converter for operating the synchronous motor 15 in an OL variable manner, it is clear that a cycloconverter or a forced commutation type inverter system can also be used. The configuration is not particularly limited.

In addition, within the scope of the present invention, (11)
A modified circuit of X? Can be configured.

"Effects of the Invention" As explained above, the present invention has advantages in that the synchronization i4i,
'Field human power of motive drive control system' Power statement 1 (
The three advantages are possible, and as a result of reducing the reactive force, the capacity of the field input power source can be reduced, etc.

[Brief explanation of drawings]

Figure 1 shows the same Jul'ft for carrying out the method of the present invention.
I', Diagram showing an example of the configuration of the motive drive system, 8I
42IA is the Va-N characteristic and T-N characteristic in the example of the present invention
Figure 3 is a characteristic diagram of a drive control system for a synchronous motor according to the present invention, and Figure 4 is a characteristic diagram of a drive control system for a synchronous motor according to another embodiment of the present invention.
a-N% characteristic and T-N characteristic diagram, Fig. 5 is a configuration diagram of a motion control system with a conventional synchronous motor, and Fig. 6 is a diagram of a conventional Va-
FIG. 7 is a characteristic diagram of a conventional drive control device for a synchronous motor. I1... Input AC power supply I2... Rectifier 13...
DC reactor 14... Inverter I5... Synchronous motor 151... Field winding 152... Rotating rectifier 15B... Induction frequency converter 154... Sensor 16... Speed reference 17... Speed controller 18...
・1)/A converter 19...α controller 191... Current detector 20... β controller 21... Field input power supply 22... Cyrisk switch 23... Voltage detector 24...East control system 241...Current detector 2b.
...Excitation reference generator T...Load torque Va...Electric power, pressure N...
Rotation Fila...Electrical budget 1st class If...Field current
Pf, ... Excitation force 'tonne force Efl ... Excitation input voltage PFα ... Input power of rectifier 12 agent Patent attorney Noriyuki Chika Takashi (one person) Fig. 1 Fig. 3 Fig. 4 Figure 5

Claims (1)

[Claims] In a synchronous motor drive7++/I control device that operates a synchronous motor that drives a square torque load at variable speed using a frequency converter that can variably control the output voltage and output frequency, the rotation speed N of the synchronous %N1FIl is sufficient. Number of revolutions N (1
In the low speed rotation speed range of 25% or less of the synchronous motor, the ratio Va/N between the rotation speed N of the synchronous motor and the 11th machine root voltage a at that time is equal to
100J and that time? 44. Root voltage va (Ioo
) The front armature storm pressure Va of the synchronous motor is set so that the ratio Va (100) / N (10G) is smaller than
A four-term electric train that is characterized by the control of! lI/l-like control method.