JPH0531394B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a synchronous motor.

Conventionally, when controlling the speed of a servo mechanism, etc., a DC motor has often been used for reasons such as ease of operation and controllability. However, DC motors are equipped with brushes and commutators,
The drawback is that regular maintenance and inspections are required to maintain normal operation. In recent years, due to remarkable progress in power semiconductors such as power transistors and control technology, and also due to the desire for maintenance-free motors, control of AC motors has been actively researched and is beginning to be used in practice.

1 and 2 show an example of the structure of a conventional electromagnet field type synchronous motor 10 and its control device, and the synchronous motor 10 has three phases (U phase, V phase) wound around a stator. , W phase) armature winding 11
A field winding 13 is wound around the rotor 12. Figure 2 shows such a conventional synchronous motor 1.
0, a laminated electromagnetic core 15 for a stator is installed in a cylindrical casing 16, and an armature winding 11 is wound on the inner circle side of this electromagnetic core 15. A plurality of slots 14 for turning are provided at equal intervals, and the armature winding 11 is formed in the slots 14 by distributed winding (or concentrated winding). Furthermore, a two-pole salient pole type rotor 12 is rotatably arranged in the space of the electromagnetic core 15 of the stator, and a field winding 13 wound around the rotor 12 is connected to the field winding 13 through a slip ring. Current is supplied from a field circuit outside the motor.

Such a synchronous motor 10 is controlled by a control device as shown in FIG. 4 are coupled, and the detection signal DS from the detector 4 is input to the rotor position detection circuit 5 and the speed detection circuit 6,
The position and rotational speed of the rotor 12 are respectively detected. Then, the speed command SI is sent to the subtracter 1 from another control device (for example, a computer).
and the speed signal SD from the speed detection circuit 6
The speed deviation ES from the proportional/integral/derivative compensation circuit 9
The output torque command ESA is input to the armature current command circuit 2 to form three-phase armature current commands SIu, SIv, and SIw, and these current commands SIu to SIw are The current is input to the armature current control circuit 3 and supplied to the three-phase armature winding 11 of the synchronous motor 10 as armature currents Iu, Iv, and Iw. Further, the field winding 13 of the rotor 12 is supplied with a current from the field current control circuit 8 according to the field current command FS from the field current command circuit 7 via a slip ring. It's summery. The details of the armature current command circuit 2 are as shown in FIG.
A memory (for example, ROM) 22 that stores the phase, V phase, and W phase sine waves as digital values.
The memory address setting circuit 21 selects the memory 22U according to the value of the rotor position signal RP from the rotor position detection circuit 5.
~22W of stored sine wave data is accessed. The sine wave data accessed from memories 22U to 22W is sent to DA converters 23U to 23.
W and is converted into an analog signal, and these analog sine wave signals are input to multipliers 24U to 2, respectively.
Input to 4W. Further, the torque command ESA obtained by the compensation circuit 9 is
4W and is multiplied by the sine wave signal from the DA converters 23U, 23V and 23W, and the current corresponding to the position and speed deviation ES, which is the multiplication result, is the armature current command SIu, SIv and SIw. Armature currents Iu, Iv, and Iw, which are input to the control circuit 3 and subjected to current control, are supplied to the synchronous motor 10.

In such a configuration, the armature current command circuit 2 receives the rotor position signal from the rotor position detection circuit 5.
The digital value of the sine wave stored in the memories 22U to 22W is read out according to RP, and after being converted into an analog signal by the DA converters 23U to 23W, the speed command SI is actually detected by the multipliers 24U to 24W. Since it is multiplied according to the speed deviation ES from the speed signal SD from the speed detection circuit 6, the armature current command circuit 2 outputs the speed command SI and the rotor 1.
Armature current command so that rotation speed of 2 matches
SIu to SIw will be output, and the synchronous motor 10 will output the rotor 12 through the armature current control circuit 3.
The rotation of can be controlled according to the speed command SI.

Here, the generated torque T of the synchronous motor 10 is determined by the position of the rotor 12 being θ, the relative phase between the armature current I and the magnetic flux density B being α, and the magnetic flux density B being a cosine wave centered around the position θ of the rotor 12. If we assume that each phase armature current Iu~Iw also has a cosine wave distribution synchronized with the intersecting magnetic flux density B, then T∝Bu・Iu＋Bv・Iv＋Bw・Iw = B ₀ cosθ・I ₀ cos(θ+α)+B ₀ cos(θ+2/
3・π)・I ₀ cos(θ+α+2/3・π)+B ₀ cos
(θ+4/3・π)・I ₀ cos(θ+α+4/3・π)
=B ₀ I ₀・3/2・cosα……(1). Note that B ₀ and I ₀ indicate the maximum values of magnetic flux density and armature current. At this time, if the magnetic flux density B and the three-phase currents are synchronized, α=0°, and T∝3/2・B ₀ I ₀ ...(2). Therefore, when ideal control is performed, the output torque T of the synchronous motor 10 is related only to the magnetic flux density B and the magnitude of the armature current I. Therefore, for example, if the magnetic flux density B is constant, the output torque T of the motor depends only on the magnitude of the armature current I, so good controllability similar to that of a DC motor can be expected. I can do it.

However, such a conventional synchronous motor 1
0 has a field winding 13 on the rotor 12, so the field loss is large, and a power amplifier and control circuit are required to control the field current, and in order to supply the field current to the rotor 12 side. The disadvantage is that it requires a slip ring or a rotating transformer.
Furthermore, when permanent magnets are used in the rotor as the field of a synchronous motor, the cost of the permanent magnets themselves is high, and the structure is complicated because the permanent magnets must be fixed to the rotating shaft, etc. The disadvantages are that the cost is high and it is difficult to increase the capacity. In this case, since the field size is constant, the induced voltage in the stator winding is proportional to the rotation speed,
There is also a drawback that there is an upper limit to the control rotation speed.
This also applies when direct current is passed through the field winding.

Therefore, an object of the present invention is to eliminate the drawbacks of conventional synchronous motors as described above, to be able to exhibit good controllability similar to that of a DC motor, to be not as complicated as a DC motor, and to have a rectification limit. The purpose of the present invention is to provide a highly reliable synchronous motor.

The above-mentioned object of the present invention is to provide a stator winding, which serves as an armature and a field, wound around a stator of an electric motor.
The rotor is made of a salient pole-shaped magnetic material having multiple magnetic poles, and each magnetic pole is provided with a hole to prevent magnetic deviation. A rotational position detector is connected to the rotor, and a sinusoidal three-phase armature current command value,
3 according to the sum of the sinusoidal three-phase field current command value
This is achieved by providing a control device that outputs phase currents.

FIG. 4 shows an example of the structure of a synchronous motor 30 of the present invention with concentrated winding, and a stator 31 has stator windings (hereinafter referred to as windings) 32 that serve both as an armature and a field wound in three phases. It's being passed around. A two-pole rotor 34 made of a salient pole type magnetic material (for example, silicon steel plate, magnetic steel strip, soft ferrite, etc.) is disposed in the space within the stator 31 .
The winding 32 is wound as shown in Fig. 5, and the U-phase winding of the winding 32 is connected from the input terminal U1 through the windings UP and UN to the connection point NA, and the V-phase winding is connected to the connection point NA through the windings UP and UN. is connected from the input terminal V1 to the connection point NA via the windings VP and VN, and the W-phase winding is connected from the input terminal W1 to the connection point NA via the windings WP and WN. Note that although concentrated winding is shown in this figure for convenience of explanation, distributed winding may also be used.

On the other hand, FIG. 6 shows an example of the structure of the rotor 34 of the synchronous motor 30 of the present invention, and the axially central part of the cylindrical rotor shaft 341 is equipped with a magnetic material such as a long silicon steel plate with curved ends. A rotor magnetic pole 342 formed by laminating body material plates is provided, and a plurality of rotor magnetic poles 342 are arranged at both ends of the rotor magnetic pole 342 in the axial direction and are perforated in the rotational direction. A rectangular hole 343 is provided to prevent the rotor 34 from being magnetically biased, thereby preventing a decrease in rotational torque and deterioration of controllability. In addition, although the above is a three-phase winding,
It is also possible to have two phases or a polyphase of four or more phases.

On the other hand, FIG. 7 shows another structural example of the two-pole rotor of the synchronous motor of the present invention, in which the rotor 34
In order to prevent magnetic bias, a hole 344 is formed in a rectangular or trapezoidal shape in the thrust direction.
A plurality of these are arranged in the rotation direction. Further, FIG. 8 shows an example of the structure of a four-pole rotor of a synchronous motor according to the present invention, and in this case also, 342A of laminated magnetic materials such as cross-shaped silicon steel plates are used.
A plurality of circular holes 348 aligned in the rotational direction and drilled in the thrust direction are provided at each tip of the rotor to prevent magnetic deflection of the rotor. Note that the protrusion 347 is provided for fixing a non-magnetic material, which will be described later. Furthermore, the rotor 34A of FIG. 9 is equipped with a thin plate cylindrical member 346 on the outside of the rotor in order to reduce wind resistance during rotation compared to the rotor 34 of FIG. The space between the mold rotor and the laminated plate 342 is filled with a non-magnetic material 345 such as synthetic resin, thereby allowing the rotor 34A to rotate smoothly. Further, the example shown in FIG. 10 is similar, and a thin cylindrical member 346 is attached to the outside of the four-pole salient pole rotor 34 shown in FIG. A non-magnetic material 349 is filled in the space between the rotor 34B and the rotor 34B so that the rotor 34B can rotate smoothly.

Next, the synchronous motor 3 of this invention as described above
11 shows a control device for controlling the rotor 34. A detector 4 for detecting the rotor position and rotational speed is connected to the rotor 34, and a rotor position signal RP from the rotor position detection circuit 5 is connected to the rotor 34. are input to the armature current command circuit 2 and the field current command circuit 50, and the armature current commands SAIu, SAIv, SAIw from the armature current command circuit 2 are converted into the field current commands SFIu, SFIu, SAIw from the field current command circuit 50. SFIv, SFIw are added by adders 72, 73, 74, respectively, and the added currents are used as current commands SIu, SIv, SIw to pass through the current control circuit 60 and drive currents Iu (FIu + AIu), Iv (FIv
+AIv) and Iw (FIw+AIw) are supplied to the winding 32. Here, the armature current command circuit 2 has the same configuration as that shown in FIG. 3, and the details of the field current command circuit 50 are as shown in FIG. 12. SD is input to a conversion circuit 51 having characteristics as shown in FIG.
It is designed to be input to 55W. That is,
The conversion circuit 51 outputs a constant value S ₀ when the input speed signal SD is smaller than the constant value N ₀ , and forms an inversely proportional curve of SDA=1/SD when it is larger than the constant value N ₀ . Therefore, when the rotational speed N of the rotor 34 is greater than a constant value N ₀ , the field magnetic flux density B is inversely proportional to the field speed v, so the induced voltage V of the motor is V=vBl∝v・1/ v·l=l, which is a constant value. As a result, even when the electric motor 30 rotates at high speed, the motor induced voltage V does not exceed a certain constant value, so that it is possible to control the rotation speed up to a high speed using a commercial power source. At this time, if the field current
When FIu to FIw are constant regardless of the rotational speed N of the electric motor 30, the motor induced voltage V is proportional to the rotational speed N, so high-speed rotation exceeding the power supply voltage becomes uncontrollable.

Furthermore, the rotor position signal RP from the rotor position detection circuit 5 is input to the memory address setting circuit 52 as described above, and
Memories 53U to 53 with the address signal set in
The digital value of the sine wave stored in W is read out, and the read digital value corresponding to the rotor position is converted into an analog signal by DA converters 54U to 54W and input to multipliers 55U to 55W, respectively. It's getting old. Therefore, this field current command circuit 50 has the same configuration as the armature current command circuit 2 described above except for the conversion circuit 51. The current control circuit 60 has a configuration as shown in FIG.
Armature current commands SAIu, SAIv, SAIw from the field current command SFIu, SAIw from the field current command circuit 50,
The addition currents SIu, SIv, and SIw with SFIv and SFIw are input to subtracters 61U, 61V, and 61W, respectively.
The feedback current from the current transformers 64U, 64V, 64W is subtracted, and the deviation is applied to the PID amplifier 62.
It is designed to be input to U, 62V, and 62W, respectively. And PID amplifier 62U~62W
The amplified signals are each powered by a power amplifier 63U to 63W.
The amplified currents Iu, Iv, and Iw are supplied to the motor windings 32, respectively.

The operation of such a configuration will be explained with reference to the waveform diagrams in FIGS. 15A to 15G and the timing charts in FIGS. 16A to D.

Figure 15 shows the rotation angle θ of the rotor 34, the components FIu to FIw of the drive currents Iu to Iw corresponding to the three-phase field currents SFIu to SFIw, and the magnetic flux density of the U-phase winding at the position of θ = 0. It shows the relationship between Bu and the components AIu~AIw of the drive current Iu~Iw corresponding to the three-phase armature current commands SAIu~SAIw when outputting a constant motor torque, and rotates in synchronization with the rotor 34. When the magnitude of the field magnetic flux component is constant, the field current components FIu, FIv, and FIw become as shown in A to C in the figure. That is, B∝Iuf・sinθ＋Ivf・sin(θ−2/3・π)＋Iwf・sin(θ−4/3・
π)=I ₀ sinθ・sinθ＋I ₀ sin(θ−2/3・
π)・sin(θ−2/3・π)＋I ₀ sin(θ−4/3・
π)・sin(θ−4/3・π)=I ₀ sin ² θ+I ₀
{sinθ・(−1/2)−cosθ・√3/2} ² +I ₀
{sinθ・(−1/2)−cosθ・(√3/2)} ² = I ₀
sin ² θ+I ₀ {1/4・sin ² θ+2√3/4sinθ・
cosθ+3/4cos ² θ}+I ₀ {1/4・sin ² θ−2√
3/4sinθ・cosθ＋3/4cos ² θ}=6/4・I ₀
(sin ² θ + cos ² θ) = 3/2I ₀ ...(3) Therefore, even if the winding 32 that also serves as the field winding is provided on the stator side, the magnetic flux density B generated in the salient pole rotor 34 remains a constant value. It is clear that Also,
The magnetic flux density Bu of the U-phase winding UP at the position θ = 0 is shown in Fig. 15D, and when the output torque T of the motor is constant, the armature current components AIu, AIv, AIw
are as shown in Fig. 15E to G, respectively, and since the above equations (1) and (2) hold true for the variation of the motor output torque T, the armature current corresponding to the armature current components AIu, AIv, AIw This can be achieved by changing the magnitude of the commands SAIu, SAIv, and SAIw. Note that the magnetomotive force due to the armature current components AIu, AIv, and AIw is perpendicular to the magnetic pole direction of the salient pole type rotor 34, and is controlled so that the magnetomotive force acts in the direction of greater magnetic resistance. The influence of AIu, AIv, and AIw on magnetic flux is small. As a result, Figures 4 to 6
The salient pole type rotor synchronous motor of the present invention shown in the figure has almost the same characteristics as a conventional electromagnet field type or permanent magnet field type synchronous motor.

Note that FIGS. 16A to 16D show timing charts of the main parts, and when the torque command ESA from the compensation circuit 9 decreases at time t1 as shown in FIG. The armature current commands SAIu to SAIw also decrease in level after time t1, as shown in FIG. Further, the field current commands SFlu to SFIw from the field current command circuit 50 do not change with respect to changes in the torque command ESA as shown in FIG. 16B, but the armature current commands SAIu to SAIw and the field current command SFIu The driving currents Iu to Iw from the current control circuit 60 obtained by adding the values .about.SFIw change as shown in FIG. It will change depending on the ESA.

On the other hand, in the above-mentioned control device, the armature current command circuit 2 and the field current command circuit 50 are each configured with a digital circuit using a memory, but they can also be configured with an analog circuit using a function generator. It is. That is, FIG. 17 shows another example of the armature current command circuit 2, which is a sine wave generating circuit that generates a sine wave signal sinθ in response to the position signal RP (θ) from the rotor position detection circuit 5. 25U
, a sine wave signal sin(θ
+2/3・π) 25V sine wave generator circuit,
A sine wave signal sin(θ+4/
The sine wave signal from the sine wave generation circuits 25U to 25W is input to multipliers 24U to 24W, respectively, and multiplied by the torque command ESA in an analog manner.
The multiplication results are output as armature current commands SAIu to SAIw. This allows all operations to be processed in an analog manner. 18 shows another example of the field current command circuit 50, in which the position signal RP from the rotor position detection circuit 5 is
(θ) is subtracted by π/2 by a subtracter 56, and the subtracted value (θ−π/2) is applied to each sine wave generation circuit 5.
By inputting to 7U to 57W, a sine wave signal sin(θ-π/2) is generated from the sine wave generation circuit 57U.
However, from the sine wave generation circuit 57V, the sine wave signal sin
(θ−π/2+2/3・π) is the sine wave generation circuit 57
From W is a sine wave signal sin (θ−π/2+4/3・π)
are output respectively. These sine wave signals are sent to multipliers 55U to 55W together with the speed signal SDA from the conversion circuit 51 having the characteristics shown in FIG.
The multiplication result is the field current command SFIu
~Output as SFIw. This allows all operations to be processed in an analog manner.

Next, another example of a control device for controlling a synchronous motor according to the present invention will be described with reference to FIG. 19 and subsequent figures.

FIG. 19 shows a control device equipped with a table 70 containing armature current commands SAIu to SAIw and a memory table 71 storing field current commands SFIu to SFIw in the table. The armature current command circuit 2A reads the corresponding armature current command SAIu~ from the memory table 70 at a predetermined timing based on the torque command ESA and the rotor position signal RP.
Read and output SAIw, field current command circuit 50
A reads out and outputs the corresponding field current commands SFlu to SFIw from the memory table 71 at a predetermined timing based on the speed signal SD and the rotor position signal RP. In this way, the armature current and field current are stored as a memory table, and the torque command is
Since armature current commands SAIu to SAIw are output by ESA and rotor position signal RP, and field current commands SFIu to SFIw are output by speed signal SD and rotor position signal RP, only linear control is possible. It is also possible to easily realize nonlinear control.

Further, FIG. 20 shows an example in which the motor current commands MIu to MIw input to the current control circuit 60 are formed by the motor current command circuit 80 and the memory 90, and the details are shown in FIGS. 21 and 22. show. That is, in FIG. 21, the address setting of the memory 90 is performed using the torque command ESA and the speed signal SD, and a phase-shifted sine wave is generated from the sine wave generation circuits 84U to 84W in accordance with the rotor position signal RP (θ). It's becoming like that. The data read from the memory 90 is converted into an analog signal by the DA converter 86 and then input to the multipliers 85U to 85W, where it is multiplied by the sine wave signals from the sine wave generation circuits 84U to 84W, respectively. Therefore, motor current commands MIu to MIw are formed.
Moreover, FIG. 22 is an example in which the contents of the memory 90 are divided into an amplitude memory 91 and a phase memory 92. Both the amplitude memory 91 and the phase memory 92 receive the torque command ESA, speed signal SD, and rotor position signal RP. be addressed. The amplitude data from the amplitude memory 91 is input to the multipliers 87U to 87W, and the phase data from the phase memory 92 is once latched to the latch circuits 88U to 88W, and then controlled in terms of timing to the multipliers 87U to 87W. is input. The multiplication results of multipliers 87U to 87W are each DA
It is converted into an analog quantity by converters 86U to 86W, and outputted as motor current commands MIu to MIw. Also,
Multiplying type DA converters are easily available these days, so the DA conversion stage and the multiplier can be realized with a single multiplying type DA converter.

Furthermore, FIG. 23 shows the motor current command circuit 100.
In addition to the motor current commands MIu to MIw, the three-phase voltages PVu to PVw of the motor are generated, and the three-phase voltages PVu to PVw are added to adders 65u to 65w in the current control circuit 60. It's becoming like that. FIG. 24 shows the details of the motor current command circuit 100, and the memory 90 stores the torque command.
The three-phase voltage data accessed by the address setting circuit 101 and read from the memory 90 based on the ESA and speed signal SD is converted into an analog signal by the DA converter 104, inputted to the multipliers 106U to 106W, and then read from the memory 90. The read current command data is
The signal is converted into an analog signal by the DA converter 105 and then input to the multipliers 107U to 107W. The rotor position signal RP is generated by the sine wave generation circuits 108 to 11.
3, is converted into a sine wave signal corresponding to the U phase to W phase, and is input to multipliers 106U to 106W and 107U to 107W, respectively.
From U~107W, the motor current command MIu~MIw is
Three-phase voltage PVu from multiplier 106U~106W
PVw is output respectively.

As described above, according to the synchronous motor of the present invention,
It is possible to achieve good controllability equivalent to that of a DC motor, and in principle, the controllability is superior to that of an induction motor. In addition, the rotor is made of a salient pole type magnetic material, which eliminates the need to supply current to the rotor via a slip ring, etc., and improves the reliability of the motor as there are no mechanical contact parts. In addition, since holes are provided in the magnetic pole portions of the rotor to prevent magnetic deviation, reduction in rotational torque can be suppressed. Furthermore, since the field current is passed through the stator windings, the heat generated by the field current can be easily dissipated, making it possible to downsize the motor. Furthermore, since the stator winding is wound as a conventional field winding and armature winding, there is no centrifugal force that acts when the field winding is on the rotor side. This has the advantage of being easier. Furthermore, since there is no need to use expensive permanent magnets in the rotor, it is possible to realize an electric motor that is inexpensive and has a simple structure, and it is also easy to increase the capacity.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an example of the structure of a conventional synchronous motor and its control device, Fig. 2 is a diagram showing the structure of a conventional electromagnetic field type synchronous motor, and Fig. 3 is a part of Fig. 1. 4 is a diagram showing an example of the structure of the synchronous motor of the invention, FIG. 5 is a diagram showing the state of the winding, and FIG. 6 is a perspective view showing the structural order of the rotor of the invention. 7 to 10 are structural diagrams showing other examples of the rotor of the synchronous motor of the present invention, FIG. 11 is a structural diagram showing an example of the structure of the synchronous motor of the invention and an example of its control device, and FIG. 14 are block circuit diagrams showing some details thereof, FIG. 13 is a diagram showing characteristics of some of the circuits in FIG. 12, and FIGS. 15A to 15G are waveform diagrams showing operation examples of FIG. 11. , FIGS. 16A to 16D are timing charts showing an example of the operation of the device in FIG. 11, and FIGS. 17 and 18
The figures are block configuration diagrams showing other examples of partial circuits of the control device shown in FIG. 11, and FIGS. 19 and 20 are block diagrams showing other examples of the control device for a synchronous motor according to the present invention, respectively. 21 and 22 are block configuration diagrams showing other examples of the motor current command circuit, FIG. 23 is a configuration diagram showing still another example of the synchronous motor control device of the present invention, and FIG. FIG. 3 is a block configuration diagram showing another example of a motor current command circuit. 1... Subtractor, 2... Armature current command circuit, 3
... Armature current control circuit, 4 ... Detector, 5 ...
Rotor position detection circuit, 6... Speed detection circuit, 7...
...Field current command circuit, 8...Field current control circuit,
10...Synchronous motor, 11...Armature winding, 12
... Rotor, 13 ... Field winding, 30 ... Synchronous motor, 31 ... Stator, 32 ... Stator winding, 34, 34A, 34B ... Rotor, 50 ...
Field current command circuit, 60...Current control circuit, 8
0,100...Motor current command circuit, 90...Memory.

Claims (1)

[Claims] 1. A multiphase stator winding that serves as both an armature winding and a magnetic field winding is wound around the stator of the electric motor, and a salient pole-shaped magnetic body having a plurality of magnetic poles corresponding to the multiphase stator winding is wound on the stator of the electric motor. Each magnetic pole of a rotor made of a laminate of materials is provided with a hole to prevent magnetic deviation, and the output of a rotational position detector connected to the rotor and a speed command signal of the electric motor are inputted,
according to the sum of a sinusoidal polyphase armature current command value that corresponds to the rotational position and rotational speed deviation of the electric motor, and a sinusoidal polyphase field current command value that corresponds to the rotational position and rotational speed of the electric motor. A synchronous motor characterized in that the multiphase current from a control device that outputs multiphase current is supplied to the multiphase stator windings.