JPS5937894A - Variable speed driving system for synchronous machine - Google Patents

Abstract

PURPOSE:To enable to control a vector without necessity of a magnetic flux detector or arithmetic circuit by employing a damperless synchronous machine. CONSTITUTION:A field current instruction value if* is obtained by calculating a torque current component instruction value iT* and a magnetic flux instruction value phi*. The phase difference phi1 of an armature coil crossing magnetic vector is calculated by a phi1 calculator 10. An arithmetic unit 8 obtains an armature current command value from a deviation angle theta to the armature coil axis of a field pole, the phase difference phi1 of the crossing magnetic flux vector, and torque current component instruction value iT*. This instruction value is compared with the actual value, and a frequency converter 1 is controlled so that the difference becomes zero. The field current instruction value if* is compared with the actual value, and a variable DC voltae power source 2 is controlled so that the difference bocomes zero.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable speed drive system for a synchronous machine, particularly a synchronous motor.

In recent years, the vector control method has become known as a new variable speed drive method for synchronous motors that can be handled as if it were a DC machine even though the power supplied to it is AC (for example, Japanese Unexamined Patent Publication No. 55-14
1993, JP-A-55-144793, etc.).

Such conventional vector control methods are based on the armature linkage flux, which is directly detected using a magnetic flux detector or calculated from the voltage and current of the synchronous motor, and this always matches the ± command value. This is based on a method that controls the armature current and field current. In other words, by decomposing the armature current into a magnetic flux current that is in phase with the armature interlinkage flux and a torque current that is orthogonal to this, and controlling these independently, the motor generated torque is controlled, and the control is equivalent to that of a DC machine. This is a method of trying to gain sex.

Here, the field current and the magnetic flux component current are controlled to 5 by feeding back the armature interlinkage magnetic flux obtained as described above and comparing it with the command value of the magnetic flux so that the two match. However, in this method, the armature flux linkage is determined and control is performed based on it, which requires a magnetic flux detection circuit or an arithmetic circuit, and since a magnetic flux feedback control loop is configured, the control circuit is extremely complex. It had the disadvantage of becoming a thing.

The present invention has been made to improve the drawbacks of the prior art as described above, and therefore, an object of the present invention is to
An object of the present invention is to provide a variable speed drive system for a synchronous motor that does not require a magnetic flux detection circuit or an arithmetic circuit, can simplify a control circuit, and can obtain control characteristics equivalent to a direct current machine.

Now, the damper winding installed on the rotor pole piece of a salient pole type synchronous machine has various useful effects such as blocking the field @ wire and preventing disturbance, but on the other hand, it When the magnetic current changes, the resulting magnetic flux change does not appear immediately, but appears with a time delay according to the time constant of the damper winding.When the field current and magnetic flux are transient, The disadvantage is that one-on-one correspondence is no longer possible. Therefore, assuming a damperless synchronous machine with the damper winding removed, changes in the field current will directly appear as changes in the magnetic flux, and the field current and magnetic flux will always correspond in a y1:1 relationship. It will be done.

Therefore, in such a synchronous machine, if you pay attention to the field current, you can also know the magnitude of the magnetic flux, so there is no need to detect the magnetic flux when performing vector control, and therefore, there is no need to use a magnetic flux detection circuit or An arithmetic circuit is also not required.

Furthermore, in order to effectively utilize a synchronous machine, it is necessary to keep the magnetic flux constant (the back electromotive force is constant above the base speed) and to make the load power factor 1. By the way, the generated torque of a synchronous machine is given by the vector product of the armature flux linkage vector 1 and the armature current vector i, and when F and i are orthogonal, all iH becomes an effective component, and in this case, the electric motor power steadily When the ratio becomes 1, the electric motor is used most effectively even in a transient manner. Furthermore, when the magnetic flux is kept constant, the magnitude of the armature current and the torque are proportional, making it possible to obtain control characteristics equivalent to those of a DC machine.

In view of the above, the present invention targets a synchronous machine such as a damperless synchronous machine where the field current and magnetic flux always have a g1:1 relationship, and the armature flux linkage command value F≠( (The command value is marked with an arrow) and the command 4rlL i# of the component perpendicular to the armature interlinkage flux of the armature current l (the command value i- of the parallel component is always zero). Using a simple control circuit that does not require a magnetic flux detection circuit or an arithmetic circuit, the aim is to realize a variable speed drive system for a synchronous machine that provides control characteristics equivalent to those of a DC machine.

The operating principle of the present invention will be explained below.

FIG. 1 is a vector diagram of various quantities in a synchronous motor. In the figure, the d-axis is an axis (magnetic pole axis) taken on the center line of the field magnetic pole, and the d-axis and the q-axis perpendicular thereto are fixed axes. On the other hand, assuming that the armature is rotating, and considering the central axis of the a-phase (one of three phases) winding in the armature winding, the central axis of the a-phase winding and the d-axis are Let the angle formed by θ be θ. Since the a-phase winding center axis is a rotation axis, the value of θ changes as the motor rotates.

The M axis (magnetic flux axis) taken in the direction of the armature interlinkage magnetic flux (effective magnetic flux) vector V and the T axis perpendicular to this are fixed axes.

Let Φ1 be the angle formed by the M axis and the d axis.

In addition, v'f is the armature linkage flux vector created by the field current if, FT is the reaction flux vector created by the armature current IT, υ, and as a result of the interference of Ff4CFT, the effective magnetic flux that actually exists is W. Become. jTq is the right q-axis component, and νTd is the d-axis component.

Note that the armature current 1 is generally decomposed into a component IM parallel to the armature interlinkage flux W and a component 1T perpendicular to the armature interlinkage flux W.
In the present invention, the parallel components iMt;j.

ITd is the d-axis component of IT.

The following equations are derived from the relationships among the vector quantities shown in FIG.

FsinΦ! -4'Tq -(+Laσ) 1TcO3Φ1 ・・・・・・・・・
・・・・・・(1) However, M(1t I'4q, ” d
From the relationship between equation (1) and equation (2), the sine and cosine of Φ1 are as follows.

Also, from Fig. 1, FcosΦt = Wt - FTd - M (1 if (Md + La, y) IT")
), and by substituting and rearranging equations (5)2K (3) and (4), we get the following.

Also, the current 1d and tq of d+q@ component is (3),
From equation (4), it is given in the next generation.

Based on the above, the present invention will be described in detail below.

FIG. 2 is a block diagram showing one embodiment of the present invention. In the figure, 1 is a frequency converter that supplies power to the armature circuit of a synchronous motor, and is a 2Fi homogeneous converter.

As the frequency converter 1, for example, a zychroconverter or the like is used. Reference numerals 6 and 7 designate current regulators (ACRs) that operate so that 6 and 7 match the armature current and field current of the synchronous motor 3 to desired values, respectively. 9 is a speed regulator (ASR) for making the rotational speed N of the synchronous motor 3 match a desired value N%, and the output of the regulator 9 is the torque current command value iT-%. to become a monk. 10 is a Φ1 arithmetic unit, and its arithmetic expression is given by the following expression, similar to the above-mentioned expression (2).

However, 1=current+I・aσ Note that the state is the armature linkage magnetic flux command value, and when field weakening control is performed, it is controlled according to the rotation speed. Reference numeral 11 is a calculator for the field current command value (Ifx), and its calculation formula is as follows from the above equation (6).

However, 2=Md K3= (Md +Lag) (Mq +Laσ)K4
= (Mq + Laσ)' 8 is 17%, Φ1 and the signal θ8 from the magnetic pole position detector 4.
Each of the arithmetic units 10 and 11 can be realized, for example, by storing input/output functions in a digital memory circuit and reading them out according to the input, or by using an analog circuit such as an adder or a multiplier, or by combining the digital circuit and an analog circuit. It is constructed by using together. The operation will be obvious without further explanation.

FIG. 3 is a block diagram showing another embodiment of the present invention.

The embodiment shown in FIG.
In A (#), the d and q axis components of the current command value IT, 1T
d7. A circuit 10 for calculating ITq■ is provided, and a three-phase current calculator 8 calculates the three-phase current command value 1 from the "T d"t i T layer and θ. +, ibv, and 1c4 are calculated; in other respects, there is no difference from the embodiment shown in FIG.

In FIG. 3, the torque current command value 6 included and the magnetic flux command value J-X are calculated by the calculator 10' to calculate the current command values for the d and q axis components! Td'', IT, and Kukaku are calculated.The calculation formula is as follows from the above equations (7) and (s).

Arithmetic unit 8' stroke 1. '! Td% + ITq” and the signal θ from the magnetic pole position detector 4, each phase current command value 1 of the synchronous motor is determined.
a■.

ib%, l. (1) is a q-operator which calculates (2), and its calculation formula (%) is used.The rest of the structure and operation of this embodiment are the same as those of the embodiment shown in FIG. 2, so a description thereof will be omitted.

According to the present invention, in a variable speed drive system for a synchronous machine using a current-controlled frequency converter, a simple control circuit can be used without constructing a complex magnetic flux feedback control loop using a magnetic flux detector or an arithmetic circuit. This enables highly efficient variable speed operation with constant armature flux linkage and motor power factor of 1.

[Brief explanation of drawings]

/Hi' (Figure 1 is a vector diagram of various quantities in a synchronous motor, and Figures 2 and 3 are block diagrams each showing an embodiment of the present invention. Description of symbols 1...Current control Type frequency converter, 2...
・Current control rectifier, 3...Synchronous motor, 4.
...Magnetic pole position detector, 5...Speed detector, 6,7...Current regulator, 8,8'...
・3-phase current command value calculator, 9...speed regulator,
10...Φ1 computing unit, 10...ITd
``+ 'Tq'' operator q- device, 11... if yellow operator agent Patent attorney Akio Namiki Agent Patent attorney Kiyoshi Matsuzaki Figure 1 'lr Shinyu l'F' Hiki Shin Mountain

Claims (1)

[Claims] 1) The armature circuit of the synchronous machine is supplied with power from a variable frequency variable voltage power supply that uses current as the manipulated variable, and the field circuit is supplied with power from a DC variable voltage power supply that uses current as the manipulated variable. This is a variable speed drive system for a synchronous machine in which the synchronous machine is driven at a variable speed by being given a torque current component command value i of the armature current and a command value 1 of the magnetic flux interlinked with the armature winding. The first element, which calculates and outputs the field current command value lfyellow from the torque current component command value iT+ and the magnetic flux command value F-%, is the same (the torque current component command value l- and A second element that calculates and outputs the phase difference Φ1 of the armature winding flux linkage vector with respect to the magnetic pole direction of the field pole from the magnetic flux command value 1, and the deviation angle of the field pole with respect to the armature winding axis. a magnetic pole position detector that detects and outputs θ; a phase difference Φ1 between the torque current component command value I$ and the interlinkage magnetic flux vector output from the second element; and a toilet position output from the position detector. The third element which calculates and outputs the armature current command value from the angle θ and the field current command value If output from the first element is compared with its actual value, and the difference is zero. 5, the means for controlling the DC variable voltage power supply compares the armature current command value outputted from the third element with its actual value, and controls the variable frequency control so that the difference becomes zero. A variable speed drive system for a synchronous machine, characterized in that it comprises means for controlling a voltage power supply. 2. In the variable speed drive system according to claim 1, the second element comprises: The torque current component command value l
d-axis component command value of torque current component from T- and magnetic flux command value W%! Td" and the q-axis component command value ITq-4 are determined and outputted, and the third element is the iTd"
A variable speed drive system for a synchronous machine, characterized in that the element is an element that calculates and outputs an armature current command value from ITq and θ.