JPS6087686A - Inverter drive permanent magnet exciting rotary electric machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical field to which the invention pertains] The present invention relates to a rotating electrical machine that is supplied with power via an inverter and is excited by a permanent magnet disposed in a rotor, in which the current busyness of the electrical machine windings is Relates to those with an influencing adjustment device.

[Prior art and its problems]

Kakaru Denki is a specialized magazine 11! ITZ Volume 100 (1979
Year).

Known from pages 1382 to 1386.

In this machine, the excitation and therefore the induced voltage (electromotive force) at a given rotational speed are not affected. - The range of torque rotation speed of this electric machine is determined based on the maximum terminal voltage of the inverter and the electromotive force of the electric machine which is proportional to the rotation speed.

Dr. H. Grotstol len's university teaching qualification thesis ``Introduction to three-phase AC technology in electric servo drive'' (1
982), it has been known to apply a steady current for demagnetization in the direct direction of the electric machine in order to widen the range of torque rotation speed in the case of a permanent magnet excitation rotation-i machine. At this time, reversible demagnetization of the permanent magnet is performed only when the current is flowing, and the permanent magnet returns to its original excitation state after the current is stopped. The disadvantage of this method of field weakening is that it imposes a strong thermal overload on the electrical machine. This is because the loss due to the additionally required large constant diameter in the vertical axis direction far exceeds the loss during rated continuous rotation.

[Purpose of the invention]

This invention is based on a permanent magnet-excited rotating electrical machine and an attached adjustment device that can change the torque and rotational speed range without using a steady current that imposes a strong heat load on the electrical machine and causes large losses. The purpose is to configure.

[Means for achieving the purpose]

According to the invention, this purpose is achieved in the R machine mentioned at the outset:
Depending on one or more operating variables, the regulating device is controlled by a progress control device connected in front of it, so that the electrical windings can be supplied with a current To for a short time in the normal axis of the machine via the inverter. This is achieved by making the current flow such that the ampere turns produced in the vertical direction by this current cause an irreversible change in the magnetization state of the permanent magnet. Since it is possible to demagnetize a permanent 6B stone by applying a demagnetizing current in the vertical direction for a short period of time, the permanent magnet adopts a new (E) state with less permanent flux density. Even after stopping the demagnetization 1W flow, this new (magnetized state) is maintained. Due to the weakened excitation field of the electric machine, it is possible to extend the range of torque and 180 to higher oral numbers. .

By supplying a current in the opposite direction to the vertical axis of the electric machine, the permanent magnet can be magnetized again, thereby increasing the excitation magnetic flux, so
The torque and speed ranges gradually return to their original limits.

The principle of the present invention of field weakening by irreversibly changing the magnetization state of the permanent magnets is independent of whether the electric machine is operated as an electric motor or as an Fk generator. The type of regulating device, ie current regulator or voltage regulator, is also not important. However, it must be medically proven that a current can be applied based on the above-mentioned principle, and this can be achieved particularly easily by means of a current regulator.

[Embodiments of the invention]

In principle, it is possible to use a single permanent magnet whose magnetization state can be irreversibly influenced for the excitation of an electric machine, but the advantage of manufacturing technology 11 is that it is possible to The magnets (IB magnetically arranged in parallel or in series, with a small
At best, this is achieved by causing the magnetization state of one sub-magnet, which has a smaller coercivity than the remaining sub-magnets, to be irreversibly altered by a direct-axis current. In addition, for each magnetic pole, at least three sub-magnets are provided magnetically in parallel, and one of these sub-magnets has a centrally located part 1-.
It has been found to be advantageous for the stones to have a smaller coercive force than the externally arranged partial magnets. The magnetic field for demagnetization or magnetization appears above all in the center of the magnetic poles, so that the above-mentioned partial magnets are completely contained in this magnetic field.

Since the outer partial magnets do not undergo an irreversible change in their magnetization state, the minimum excitation field is ensured. This also applies in the case of a series arrangement of partial magnets.

The partial magnet with smaller coercive force is kl N t,
C.

It is preferable to use magnetic material or Fe Cr Co magnetic material. Since magnets made of these powerful materials have a high residual magnetic flux density, a high excitation magnetic flux can be obtained in the magnetized state of the partial magnet. However, these magnets can be easily demagnetized or magnetized due to their low coercivity. - Ferrite material is advantageous as a magnet whose magnetization state should be switched when economics are important.

The structure of the permanent magnet can be modified so that pole pieces made of soft magnetic material are mounted on all or part of the permanent magnet.

These pole pieces keep the armature field generated by the torque-generating transverse currents away from the permanent magnet, so that the armature transverse field is especially taken into account when sizing magnets whose magnetization state is to be irreversibly switched. Bamboo wood will run out. Moreover, each a-pole of the u-trochanter can be configured in various ways, for example, by selectively using partial magnets in series or parallel configuration for each magnetic pole, or by using different magnet lateral slopes. I can do it.

It is expedient for the magnetization state switching process in the electrical machine to be regulated in a coordinated manner by means of a control device which influences the regulating device. In this case, the magnetization state switching process can be initiated depending on a predetermined limit rotational speed or depending on the terminal voltage of the electric machine. Various values can be selected as limit values for the magnetizing and demagnetizing operations.

Any interference that the current operating state of the electrical machine has on the switching of the magnetization state is eliminated in that during the magnetization state switching process, at least only one set point of the current in the vertical axis is provided by the curve i1i control device. The magnitude of this target value can be selected depending on the desired magnetization state, or its value can be made equal to the maximum value. This setpoint value can be given by a progress control device for a fixed but selectable period of time depending on the excitation flux desired in each case, or it can be given by the value of the difference between the setpoint value and the actual value of the current in the vertical axis. is given until it falls below a fixed but selectable value. Furthermore, it has been found that it is better to lower the target value of the horizontal axis current to zero during the magnetization state switching process.

Furthermore, a second adjustment is prefixed with a sustained current acting in the vertical direction which, even after irreversible demagnetization of the permanent magnet or its sub-magnets, additionally still brings about a reversible change of the magnetization state of the magnet. Advantageously, the armature windings are supplied by means of a device. This allows the torque rotational speed range to be further expanded.

Since this further weakening of the excitation field takes place in the demagnetized state of the permanent magnets, only a correspondingly low sustained current is required for reversible demagnetization, which causes the electrical machine to be subject to thermal overload. You will not receive any.

[Embodiments of the invention]

Next, embodiments of the present invention will be described in detail with reference to drawings showing two embodiments of a rotating electric machine and an embodiment of a drive circuit thereof based on the present invention.

In FIG. 1, reference numeral 1 denotes a three-phase AC rotating electric machine having a rotor with permanent magnet excitation, which is supplied with power via an inverter 2 from a 380cm three-phase AC power source.

A current regulator 3 is attached to the inverter 2, and this current regulator is connected to a transient control device 4 that receives a target value jdw' for the direct axis 'j (-1) and a target value i1w' for the horizontal axis current.
and is supplied with. During the operating period in which no magnetization changes are carried out, the progress control device 4 receives from the upstream second regulating device 4 the setpoint value id□ for the direct-axis current and the setpoint value 1q1v for the horizontal-axis current and changes these setpoint values. is passed on to the current regulator 3 as it is. Rotation speed measuring device 5 coupled to electric machine
The progress control device 4 is notified of the current rotational speed of the electric machine via. When the electric machine rotation speed reaches the limit, the progress control device 4
starts working and gives the current regulator 3 a new target value 1dw' for the direct axis current. The permanent magnets disposed in the rotor are irreversibly demagnetized or magnetized by the current controlled in the vertical axis direction of the electric machine 1 via the inverter 2 based on the target value of the current regulator 3. . Direct axis current target value 1d
When the value of the difference between w' and the actual value id falls below a predetermined value, the progress control device 4 ends the magnetization state switching operation. A rotational angle measuring device 6 (rotor position sensor) is coupled to the electric machine 1, and its output signal is supplied to a coordinate axis converter 7. This converter also has three electrical currents 'an lb
, lc are supplied. Actual value l of the current in the coordinate system fixed to the stator by coordinate axis transformation
a, tb, tc are transformed into the actual values of the currents id, i, in a coordinate system fixed to the rotor. Since the output end of the coordinate axis converter 7 is coupled to the current regulator 3, 'I
! The controller receives the actual value at the time.

In order to realize a specific characteristic, it is of course necessary to supply the current regulator 3 with the output signal of the angle correction measuring device 6 in addition to the above.

The input signal to the second upstream regulator 8 consists of the rotational speed setpoint value nW and the rotational error actual division value n. The output signal of the rotational a-measuring device 5 serves the latter role. This upstream second regulating device 8 has an output signal transducer for setting the horizontal axis current.
and a controller that generates an output signal 1 dw to provide a sustained current that does not irreversibly change the magnetization state of the permanent magnet according to the rotation speed. Become.

In the structure shown in FIG. 2, three partial magnets 11 for one excitation mwLy with a pole pitch of 1.

12 and 13 are magnetically connected in parallel. The two outer partial magnets 11, 12 are made of a magnetic material with high integrity. The magnetization edges of these partial magnets are not irreversibly affected by the magnetization state switching operation.

On the other hand, the centrally relocated partial magnet consists of a material with a low coercive force. If the outer partial magnets 11, 12 are made of ferrite material, the central partial magnet 13 can be an alnico magnet. When rare earth cobalt magnets are used for the outer partial magnets, the central partial magnet can be made of ferrite material or alnico.

The width of the central partial magnet 13 is approximately equal to one quarter of the pole pitch t. This dimension of the central sub-magnet 13 makes it possible to generate a magnetic field of sufficient strength for an irreversible switching of the magnetization state even at the ends of this sub-magnet. Magnetization and demagnetization are performed by short-term current impulses in the vertical direction of the machine. The magnitude of the current depends on the desired state of magnetization and the coercive force of the permanent magnet. Furthermore, in the structure consisting of multiple partial magnets as shown in FIG. 2, due to the relatively high residual magnetic flux density of the central partial magnet 13, when the electric machine is sufficiently magnetized, the magnetic flux distribution along the magnetic pole face becomes very sinusoidal. It has the advantage of being a good approximation. Such a good approximation is generally not applicable to permanent magnet excited rotating electric machines.

FIG. 3 shows a series connection of two partial magnets 31, 32. The partial magnet 32 has a coercive force /J1 smaller than that of the partial magnet 31, and is arranged closer to the stator of the electric machine 1.

Thereby, it is easily demagnetized by the magnetic field generated by the direct axis current. In FIGS. 2 and 3, the structure of the magnet is shown as a developed view of a rotor and a stator, respectively, with line 9 indicating the stator and line 10 indicating the rotor.

In the transient control device 4 for regulating magnetization state switching shown in FIG. 4, the magnetization state switching operation is opened when a given limit rotational speed is exceeded. The magnitude of the actual value of the rotational speed I
n+ is supplied to the first comparator 21. This comparator circuit has hysteresis. The I signal at the output of the first comparator 21 means that the machine should be operated with a reduced excitation field; the L signal means that the machine should be operated with a sufficient excitation field. It is better to select the limit rotation speed for magnetization of the electric machine to be lower than the limit rotation speed for demagnetization.This is because during magnetization, the increasing electromotive force will hinder the magnetization process, while during demagnetization, This is because the decreasing electromotive force favorably affects the demagnetization process.The progress control device in the present invention ends the magnetization state switching process when the actual value id of the direct axis current reaches a predetermined limit value. So,
A second comparison 64 for the direct axis current is required. At the output of this second comparator n, a direct current actual value signal id
When reaches the limit value determined by the threshold value of the second comparison 64, the L signal appears and the output of the second comparison 6B appears, as long as the actual value signal ld has not yet reached this limit value. An H signal appears at the end. The second comparator n can have different threshold values depending on the desired magnetization state of the permanent magnet.

The demagnetizing operation is started when the magnitude In+ of the actual rotational speed value reaches the threshold 1 of the first comparator 21.

This causes a transition from the L signal to the H signal at the output end of the first comparator 21. The H signal sets the D-tine's free, negative, and 7th stages to demagnetizing operation. Depending on the output of Furi, Pflo, and Fustage, the changeover switch is controlled via the 011 game) 25.
The setpoint value 1dw supplied by the upstream second regulator is disconnected from the current regulator 3. At the same time, the maximum value is fixed at -10V in this embodiment by using a changeover switch.
A new target value 1dw'l is input to the target value input terminal of the current regulator 3. The polarity of the new target value 21 is preset by a further changeover switch n controlled by the output of the first comparator 21, so that this target value 1dw
Magnetization or demagnetization is performed depending on the polarity of l.

As already mentioned, the second changeover switch valley is switched in dependence on the output signal of the first comparator 21.

When the actual value id of the direct axis current reaches the desired value, the second
The signal L-1δ at the output terminal of the comparator n resets the free, negative, and bustagem from the deceleration operation. This causes the change-over switch (a, fI) to be switched to the position opposite to that shown, so that the setpoint value idwy 'l for the direct and transverse flow from the second upstream regulating device.
qw is again given to the current regulator 3.

In principle, the magnetization process proceeds in exactly the same way. However, at this time, the FRI, 1F, and FSTAGE rows, which are similarly configured in the D type, are set for the magnetization process. This pretend,
The output signals of Fufuro and Fstage Sae similarly control the changeover switch A via the 011 gate 5. With this changeover switch, the new target value 1dwl is changed again to the current-tube device [3
connected to. During the magnetization process, an L signal appears at the output terminal of the first comparator 21, so the second switch, trough, is controlled to a position opposite to that shown. For this purpose, the current regulator 3 is supplied with the maximum value +lO■ as the new setpoint value i, IWl.

In order to reduce the load on the inverter 2, the target value iqwI of the horizontal axis current is set to zero during the magnetization state switching process.

This is done by means of another contact on the changeover leg, by means of which the setpoint value 1qvr is disconnected from the current regulator.

It should be noted that in this embodiment, the magnetization changing operation is started when a predetermined limit rotational speed is reached, and is ended when the direct axis current jd reaches a predetermined value. In some other applications, it may be advantageous if the above-mentioned limit values for rotational speed and current are provided as a function of one or more operating variables of the electrical machine. Of course, in this case both comparators 21. The threshold voltage must be set by means of an additional input signal corresponding to such operation.

〔Effect of the invention〕

The range of torque and rotational speed of variable speed rotation 'K'rRJ obtained by supplying variable frequency power via an inverter to a synchronous machine whose rotor has magnetic poles made of permanent magnets is the maximum terminal voltage of the inverter and It is determined by the electric power of the electric machine, which is proportional to the rotation speed. In order to increase this torque rotation range to even higher rotational speeds, the field must be weakened to reduce the electromotive force of the electric machine.

In this invention, a progress control device is provided before the regulator that controls the 961f supplied to the TEMA winding from the inverter, and for example, when the rotation speed of the electric machine reaches a certain limit value, the progress control device controls the Based on the directive 'IE fi
A large current is supplied to the direct axis of g for a short period of time, and the permanent magnet is irreversibly demagnetized by this current. Even after this demagnetizing current is cut off by the progress control device, the field weakening is maintained, so there is no need to continue supplying the direct axis current to maintain the field weakening as in the past. It is possible to avoid thermal overload on electrical equipment and avoid power loss. In order to restore the value state of the permanent magnet to its original state, use transient control or another command from the device. i! It is sufficient to supply reverse current for a short period of time to the straight axis of the machine.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of an inverter-driven permanent magnet-excited rotating electrical machine and its adjustment device according to the present invention, and FIGS. 2 and 3 are diagrams showing a plurality of partial magnets of the rotating electrical machine shown in FIG. 1. Schematic diagrams showing different embodiments of excitation poles,
FIG. 4 is a circuit diagram showing an embodiment of the progress control device shown in FIG. M1. In the drawings, l is a permanent magnet excited rotating electric machine, 2 is an inverter, 3 is a current regulator, 4 is a passing side 4IiI device, 8 is a second regulator, 11 , 12 , 13 , 31 , 32
is the partial magnet, ldw' is the target value for the direct axis current during the magnetization state switching process, and i1w/ is the target value for the horizontal axis current during the magnetization state switching process.

Claims (1)

[Scope of Claims] l) A rotating electrical machine supplied with power via an inverter and excited by a permanent magnet disposed in the rotor, which is equipped with a regulating device that influences the current in the electrical machine windings, As a function of one or more operating variables, this regulating device is controlled by an upstream progress control device such that the electric machine windings are briefly supplied with a current in the direction of the vertical axis of the electric machine via an inverter, and this current An inverter-driven permanent magnet-excited rotating electric machine, characterized in that the size of the current is selected to irreversibly change the magnetization state of the permanent magnet due to the ampere turn generated in the vertical axis direction by this current. 2. An inverter-driven permanent magnet excited rotating electrical machine as set forth in claim 1, wherein the regulating device is a current regulator. 3) Claim 1 or 2. In the electric machine described above, a plurality of partial magnets provided per pole are magnetically arranged in parallel or in series, and at least the magnetization state of the partial magnet having a coercive force smaller than that of the remaining partial magnets is changed by a direct-axis current. An inverter-driven permanent magnet-excited rotating electrical machine characterized by being irreversibly changed. 4) In the electric machine according to claim 3, at least three partial magnets are provided magnetically in parallel between the magnetic poles, and the partial magnet located at the center of these partial magnets is placed on the outside. An inverter-driven permanent magnet-excited rotating electric machine characterized by having a coercive force smaller than that of a partial magnet. 5) The electric machine according to claim 3, characterized in that for each magnetic pole, at least two partial magnets are arranged magnetically in series, and one of these partial magnets has a smaller coercive force. Inverter-driven permanent magnet excited rotating electric machine. 6) In the electric machine according to any one of claims 1 to 5, an inverter-driven permanent magnet excitation characterized in that a magnetic pole piece made of a soft magnetic material is attached on the permanent magnet. Rotating electric machine. 7) An inverter-driven permanent magnet-excited rotating electrical machine according to claim 4 or 6, characterized in that a magnetic pole piece is provided only on the central partial magnet. 8) An inverter-driven permanent magnet-excited rotating electric machine according to any one of claims 1 to 7, characterized in that each magnetic pole of the electric machine is configured in a different manner. 9) The electric machine according to any one of claims 1 to 8, characterized in that the magnetization state switching process is introduced by a progress control device depending on a predetermined limit rotation speed. Inverter-driven permanent magnet rotating electric machine. 10) In the electric machine according to any one of claims 1 to 9, the magnetization state switching process is introduced by a transition type control device depending on a predetermined limit value of the electric machine terminal voltage. An inverter-driven permanent magnet-excited rotating electric machine characterized by: 11) The electric machine according to any one of claims 1 to 1O, characterized in that only a target value for the direct axis current is given by the progress control device even if there is no snacking in the magnetization state switching process. Inverter driven permanent magnet excited rotating electric machine. 12. In the electric machine according to claim 11, the target value for the direct axis current during the magnetization state switching process is such that the value of the difference between the target value and the actual value is a predetermined but freely selectable value. An inverter-driven permanent magnet-excited rotating electric machine that is energized by a progress control device until the temperature drops below 4'. 13) An inverter 1 in the electric machine according to claim 11, characterized in that the target value for the direct axis current during the magnetization state switching process is given for a predetermined but selectable time. Drive permanent magnet excited rotating electric machine. 14) An inverter-driven permanent magnet-excited rotating electric machine according to claim 12 or 13, wherein the target value of the horizontal axis current is set to zero during the magnetization state switching process. . 15) In the electric machine according to any one of claims 1 to 14, ``in a demagnetized state of the permanent magnet or its partial magnet, a second an inverter-driven permanent magnet, characterized in that the target value is of such a magnitude that the corresponding direct-axis current causes only a reversible change in the magnetization state of the permanent magnet or its sub-magnets. Excited rotating electric machine.