JP2000166294A - Group operation control method and system of synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a group operation control method of a synchronous motor for satisfying both the reliability and economy of a system. SOLUTION: A plurality of synchronous motors 51-5n are subjected to variable speed control operation. With one portion 51 of the plurality of synchronous motors 51-5n as a pilot motor, the magnetic pole position of the rotor of the pilot motor 51 is detected by a magnetic pole position detection sensor 6. The output voltage and the output frequency of a power circuit part 3 are controlled so that the phase angle formed by the magnetic pole position of the detected pilot motor 51 and the rotary magnetic field generated by stator coil winding is within a specific range. Also, by commonly supplying the output power of the power circuit part 3 to the plurality of synchronous motors 51-5n, the plurality of synchronous motors 51-5n are subjected to variable speed control operation so that they reach the same speed. When either one of the plurality of synchronous motors 51-5n fails, overcurrent detection protection devices 81-8n stop power supply to the synchronous motor that failed. The other synchronous motors continue to operate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous motor group operation control method and system for stably controlling a plurality of synchronous motors connected to the same power supply at a variable speed.

In a special building or clean room where strict temperature control is required, in order to uniformly and accurately control the temperature of the entire room, instead of a general batch flow control method, blow-off / discharge fans are dispersed. A system that can finely control the flow rate of each fan is used. In this type of air conditioning system, it is necessary to perform distributed group operation control in order to control a large number of distributed fans at the same speed.

As this kind of group operation control system, a system for driving a plurality of induction motors at a variable speed by using a power converter that converts power (for example, Japanese Patent Laid-Open No. 59-9689).
No. 6) and a system for driving a plurality of synchronous motors at a variable speed (for example, Japanese Patent Publication No. 51-3046). However, an induction motor generally has a lower operating efficiency than a synchronous motor, and a current of about five times that at a steady state flows at the time of startup. Therefore, a large-capacity power converter is used for group operation of a large number of motors. There is a problem that must be. In particular,
Synchronous motors are overwhelmingly more advantageous than induction motors in terms of operating efficiency for motors with several hundred watts per unit, such as variable speed drive motors for air conditioning fans in buildings and clean rooms. . This is necessary in terms of energy-saving operation regardless of the presence or absence of the variable speed operation.

On the other hand, synchronous motors are advantageous in terms of operating efficiency, but have the disadvantage that they tend to lose synchronism due to vibration, overload, transient phenomena, and the like. In order to prevent this step-out phenomenon and realize stable control, a magnetic pole position detection sensor (PPS: Pole Position Sensor) is provided to constantly monitor the magnetic pole position of the rotor, and the magnetic pole position and the stator winding are monitored. In order to control the phase angle (torque angle) with the rotating magnetic field generated by the motor to an optimum angle of about 90 °, a synchronous motor that controls the voltage and frequency of the electric power supplied to the stator winding with a power converter is used. Used. Such a synchronous motor is generally known as a brushless DC motor (BLDC motor).

FIG. 11 is a block diagram showing a configuration of a group operation control system in which a plurality of BLDC motors are connected.
AC three-phase commercial power supplied from an AC commercial power supply line 101 is converted into a DC voltage by a rectifier (CON) 102, and then a plurality of BLDC motors 103 ₁ ,
103 _2, 103 _3, ..., it is supplied to 103n. Each of the BLDC motors 103 _{1 to} 103 n is a synchronous motor (S
_{M) 104 1, 104 2,} 104 3, ..., 104n and an inverter for variable speed controls the synchronous motor _{104 1 ~104n (INV) 105 1} , 105 2, 105 3, ..., 10
5n and a magnetic pole position detection sensor (PPS) 10 for detecting the magnetic pole position of the rotor of each of the synchronous motors 104 _{1 to} 104n.
6 _1, 106 _2, 106 _3, ..., it is constituted by a 106n. The inverters 105 _{1 to} 105 n control the output voltage and the output frequency according to the outputs of the magnetic pole position detection sensors 106 _{1 to} 106 n. Thereby, each synchronous motor 104
Variable speeds _{1 to} 104n are independently controlled based on the detection values of the magnetic pole position detection sensors 106 _{1 to} 106n provided so as to maintain the optimum torque angle. Here, when performing the group control, by adding a common signal to the speed command signal system, each synchronous motor (BLDC motor) performs the variable speed control operation at substantially the same speed.

[0006]

However, in the above-described conventional group operation control system for BLDC motors, each synchronous motor is provided with a magnetic pole position detection sensor and a dedicated electronic control circuit, and each of them is a complete BLDC motor. They are running in parallel. For this reason, in each synchronous motor, it is necessary to connect three Hall sensors for magnetic pole position detection and eight to nine sensor signal lines for connecting the Hall sensors in addition to the driving three-phase power line. This has been a major cause of a reduction in circuit reliability. Further, the cost of the wiring and the cost of the magnetic pole position detection sensor and the inverter are not negligible in terms of economy in a distributed control type air conditioning system in which a large number of fans, such as tens to hundreds, are installed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a synchronous motor group operation control method and system that can satisfy both system reliability and economy.

[0008]

According to the present invention, there is provided a group operation control method for a synchronous motor, wherein the plurality of synchronous motors are controlled at a variable speed by power conversion means. Some of the motors
The output voltage and the output of the power conversion means are set so that the phase angle between the detected magnetic pole position of the rotor and the detected magnetic pole position and the periodically changing magnetic field generated by the stator winding falls within a predetermined range. A pilot motor for controlling the frequency is provided, and the output power of the power conversion means is supplied to the plurality of synchronous motors in common, so that the plurality of synchronous motors are controlled to operate at the same speed,
Abnormality detection protection means provided in each of the power supply paths, for detecting when an operation abnormality has occurred in any of the plurality of synchronous motors, and for stopping power supply to the synchronous motor in which the operation abnormality has occurred; And the operation of other synchronous motors is continued.

According to the present invention, the magnetic pole position of the rotor is directly or indirectly detected by the magnetic pole position detecting means in a part of the plurality of synchronous motors which are controlled in group operation, and is transmitted to the power converting means. By providing the pilot motor for feedback, torque angle control of the pilot motor is performed, and at the same time, output voltage and frequency-controlled output power of the power conversion means are supplied to other synchronous motors. As long as the motors are operated under substantially the same specifications and under similar load conditions, the same control as when the torque angle control is performed on all the synchronous motors can be performed.

However, according to the present invention, since all synchronous motors are operated at the same speed based on the torque angle control of the pilot motor, any one of the synchronous motors is stopped due to restraint or step-out. If so, the effect is on all other synchronous motors. Therefore, in the present invention, when it is detected that an operation abnormality has occurred in any of the synchronous motors, the power supply to the synchronous motor is stopped.
The same control is performed as when the synchronous motor is not connected. For this reason, other normal synchronous motors are continuously operated without being affected.

According to the present invention, even in a system having a large number of synchronous motors, only some of the synchronous motors are provided with a pilot motor for controlling magnetic pole position detecting means and power conversion means, and the other synchronous motors are provided with these. Since there is no need, the overall cost can be reduced while ensuring the reliability of the system. Further, even if one of the synchronous motors becomes abnormal in operation, it is possible to prevent the synchronous motor from affecting the operation of the other synchronous motors. it can.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a synchronous motor group operation control system according to one embodiment of the present invention. AC three-phase commercial power supplied from the AC commercial power supply line 1 is converted into DC power by the rectifier circuit (CON) 2, and the power circuit unit (PW) 3 achieves an ideal power factor and operating efficiency. Is converted into a three-phase AC output power of a variable voltage variable frequency (VVVF) controlled as described above, and the three-phase AC output voltage is transmitted via a common VVVF output line 4 to a plurality of synchronous motors (SMs) 5 ₁ , 5. ₂ ,
5 _3, ..., it is supplied to 5n. Multiple synchronous motors 5
Some of the ₁ through 5n, one in this example synchronous motor 5 ₁
Pole position detection sensor (PPS) 6 and control circuit 7
Is provided, the pilot motor 1 by these synchronous motor 5 _1, the magnetic pole position detecting sensor 6 and the control circuit 7
0 is configured. Magnetic pole position detecting sensor 6 detects a magnetic pole position of the motor 5 ₁ of the rotor. Control circuit 7, the synchronous motor 5 ₁ a detected value is controlling the power circuit part 3 so that the operation efficiency and the ideal power factor. Power circuit unit 3 supplies under the control of the control circuit 7, a common VVVF output voltage whose voltage and frequency are adjusted to the synchronous motor 5 ₁ through 5n.

[0013] The power supply side of the plurality of synchronous motor 5 ₁ through 5n, overcurrent detection and protection apparatus 8 ₁ ~8n curtailing power supply path instantly detect an overcurrent is inserted. The overcurrent detection and protection apparatus 8 ₁ ~8n, for example, can be used no-fuse breaker (NFB) and fast trip fuse like. Detection signal from the overcurrent detection and protection apparatus 8 ₁ ~8n is displayed in the form of identifying the synchronous motor there example abnormality on the display device 9 provided on the operation panel or the like.

FIG. 2 is a diagram showing a configuration example of the pilot motor 10. As shown in FIG. A stator 13 on which a stator winding 12 is applied is mounted on an inner peripheral surface of a cylindrical case 11 whose inside is sealed, and a rotor 14 is arranged so as to be surrounded by the stator 13. The rotating shaft 15 of the rotor 14 is connected to the case 1 via bearings 16 and 17 mounted at the center of both ends of the case 11.
1 rotatably supported. The rotor 14 forms a magnetic pole portion 18 that is magnetized or excited in the radial direction so as to follow the rotating magnetic field generated by the stator winding 12. The magnetic pole portion 18 may be formed by appropriately embedding and arranging a plurality of permanent magnets 22 in a rotor core 21 as shown in FIGS. 3A to 3C, for example, or as shown in FIG. As shown in (1), a magnetic pole may be formed by exciting the excitation coil 24 wound around the iron core 23 by supplying a direct current thereto. Further, as shown in FIG. 5E, a configuration may be adopted in which only the iron core 25 formed so that the magnetic resistance in the rotation direction increases or decreases. This is known as a VR (Variable Reluctance) type motor.

The above-described magnetic pole position detection sensor 6 is provided near the magnetic pole portion 18 of the rotor 14 and is mounted on a substrate 32 of a control device 31 arranged on one side of the case 11. The control device 31 receives VVV from the magnetic pole position detection signal.
A control circuit 7 for generating the F output is built in.
Incidentally, the synchronous motor 5 ₂ through 5n other than the pilot motors, magnetic pole position detection sensor 6, the control device 31 and the substrate 32
Is not provided, and the VVVF output is directly supplied to the stator winding 12. Therefore, the power circuit part 3, which is controlled by the control circuit 7, to use a capacity capable of supplying sufficient power for the total number of the group controlling the synchronous motor 5 ₁ through 5n of interest. Although this example shows an example in which the control circuit 7 is housed in the control device 31 inside the case 11, it is needless to say that the control circuit 7 may be disposed outside the case 11 or may be the same device as the power circuit unit 3. Needless to say, it may be housed inside. Further, if the power circuit section 3 and the control device 7 are arranged inside the case 11, it will be configured as a BLDC motor.

FIG. 4 shows a rectifier circuit 2 and a pilot motor 1.
FIG. 3 is a block diagram showing details of circuits relating to a power circuit unit 0 and a power circuit unit 3; The rectifier circuit 2 includes a bridge circuit including diodes D1 to D6 for rectifying a three-phase commercial power supply voltage or a thyristor having a voltage adjusting function, and a smoothing capacitor C for removing pulsation from its output to obtain stabilized DC power.
And a power consuming energy consuming circuit including a Zener diode ZD, a resistor R, and a transistor TR0. The power circuit unit 3 includes the rectifier circuit 2
A power transistor TR1 for converting the DC power supplied from the
To the protection flywheel diodes D11 to D6 connected in anti-parallel to the transistors TR1 to TR6.
D16. The control circuit 7 controls the power transistors TR1 to TR of the power circuit unit 3 based on the magnetic pole position signal of the rotor 14 detected by the magnetic pole position detection sensor 6.
6 is turned on and off.

Next, the operation of the group operation control system configured as described above will be described. In startup of the synchronous motor 5 ₁ through 5n, gradually increased from 0Hz to VVVF output frequency of the power circuit unit 3. Thus, the rotational speed of the synchronous motor 5 ₁ through 5n gradually rises. By starting in this manner, the starting current can be reduced, so that the capacity of the power control converter can be reduced, and the economical efficiency of the device can be greatly increased. In the case of a synchronous motor, the ideal torque angle (permanent magnet 22 or exciting coil 2
4 and the VVVF output voltage are applied to the stator winding 1
2 is a 90 ° electrical angle. This is because the maximum power factor is obtained when the torque angle is 90 °. However, when a load is applied to the synchronous motor and the torque angle exceeds 90 °, the synchronous motor easily loses synchronization. For this reason, some margin of control safety is expected,
The control circuit 7 controls the VVVF output of the power circuit section 3 so that the torque angle falls within a range of about 90 °, preferably in a range of 60 ° to 120 ° including a transition time. In this system, fundamentally different from the conventional synchronous motor of the commercial power supply operation, the synchronous motor 5 ₁ a torque angle (phase angle) to control the, also control torque angle of the other synchronous motor 5 ₂ through 5n ing.

[0018] Now, the voltage applied to the synchronous motor 5 ₁ through 5n to V, induce k voltage constant, main magnetic flux amount [Phi, when the IZ and motor impedance voltage drop (vector quantity), the rotational speed n of the motor , Can be expressed as:

[0019]

(Equation 1)

Therefore, the number of rotations can be controlled by adjusting the applied voltage V applied to the synchronous motor. The adjustment of the applied voltage V is performed by adjusting the DC output voltage of the rectifier circuit 2 or the control circuit 7 and the power circuit unit 3 perform PWM
(Pulse width modulation) When the control method is used, the PW
It can also be performed by adjusting the M pulse width. Further, both functions can be used in combination.

[0021] Now, the synchronization when either the load of the motor 5 ₁ through 5n is increased, the torque angle of the synchronous motor load is increased is reduced. The so-called difference voltage between the applied voltage applied to the synchronous motor and the back electromotive force increases with an increase in the torque angle, so that the current value of the synchronous motor with the increased load increases,
As a result, the output current of the power circuit section 3 and, consequently, the current value flowing through the power supply line 1 also increase. If the circuit impedance moderate exists, the increase in the power supply line 1 and the VVVF current value such as the output line 4 results in an increase of the voltage drop due to their impedance, the synchronous motor 5 ₁ through 5n
Is reduced. Further, the synchronization force acting (generated) between the parallel-connected synchronous motor 5 ₁ through 5n, the voltage of the same phase and the motor is also loaded to the synchronous motor other than a synchronous motor under load is applied Because
Rotational speed also decreases, and decreases the speed of all of the synchronous motor 5 ₁ through 5n, and the torque angle is controlled to stabilize.

[0022] Thus, in this system, synchronization does not have the magnetic pole position detecting sensor 6 and the control circuit 7 motor 5 ₂
With respect to ~ 5n, the operation is basically different from the operation of the general synchronous motor with the torque margin (the operation condition under the maximum possible torque), and it is equivalent to the feedback control operation as a kind of BLDC motor. . This point has been confirmed in experiments performed by the present inventors. That is, according to the experiment of the present inventor, in a motor group that performs group operation control with no load, a constant load is applied to one of the synchronous motors having no magnetic pole position detection sensor and control circuit 7 in the group. Although the number of rotations decreased by that amount, all the motors in the same group including the pilot motor did not vibrate (oscillate) and were operated at the same speed without loss of synchronism.

Further, in the example of the group control operation of a total of three synchronous motors, one pilot motor and two synchronous motors without the magnetic pole position detection sensor 6 and the control circuit 7, a magnetic pole position detection sensor and a The load applied from the outside to the output shaft of one synchronous motor having no control circuit 7 is adjusted to gradually increase the load from the no-load state. A restraining experiment was performed. As a result, as the load increased, the rotation speed of all motors in the group gradually decreased, and finally all the motors stepped out and stopped.

Therefore, if one of the synchronous motors in the group
If the bearings 16 and 17 are damaged or stepped out due to damage or the like and stop, all the motors in the group will stop if they are stopped. Therefore, in this system, the occurrence of such an operation abnormality is notified by the overcurrent detection protection device 8.
_{1 to} 8n are detected in the form of overcurrent to the motor, and the power supply path to the motor is immediately cut off. At the same time, an abnormality occurrence signal is output to the display 9 to indicate that an abnormality has occurred.

By doing so, the operation of another normal motor can be continued. For example, 20 to one group
In the case of a distributed group operation control system in which a large number of synchronous motors such as 30 are operated in parallel, the effect of stopping one of the synchronous motors is smaller than the effect of stopping all synchronous motors. Much smaller. Therefore, by applying this system, it is possible to avoid a situation in which all the synchronous motors of the air conditioning system temporarily stop, and the reliability of the air conditioning system is improved.

For example, in a system in which 10 to 20 fans are connected in one group, the capacity of the power circuit section 3 must be a capacity that can drive all of these motors stably. However, such a control method can be dealt with simply by slightly increasing the size of the power element in the output stage or amplifying the output stage. No special skills are required for that. As a result, by performing group control of a large number of synchronous motors using a pilot motor, the number of signal lines and the number of parts can be significantly reduced, greatly contributing to improved system reliability and economy. can do.

The present invention is not limited to the embodiment described above. As a synchronous motor to be used, for example, as shown in FIG. 5, the rotor 14 may include a cage rotor 19 coaxially arranged with the magnetic pole portion 18 in the axial direction. The cage rotor 19 functions as a torque generating means and a vibration absorbing damper of the induction motor by interaction with the rotating magnetic field generated by the stator winding 12. For this reason, by using this synchronous motor,
It is possible to select two types of starting methods, starting by the output frequency of the power circuit unit 3 and starting by the induction motor. In the group control using the pilot motor, even if one of the synchronous motors in the group stops, it is necessary to restart all the synchronous motors in the group. By using a motor, self-starting by an induction motor becomes possible.

When the induction motor is activated, when the rotation speed n of the rotor 14 approaches the synchronous speed from the asynchronous speed, the magnetic pole portion 18 attracts the rotating magnetic field and draws in the synchronous speed. Thereafter, the cage rotor 19 functions as a vibration absorbing damper to prevent out-of-step or the like due to vibration or transient response, thereby ensuring stable operation of the system. FIG.
(F) is an example of a type in which a permanent magnet 22 and a rotor conductor 26 are embedded in a rotor core 21 to integrally form a magnetic pole portion 18 and a cage-shaped rotating portion 19.

Further, the present invention is not limited to a system in which only one synchronous motor in a group is used as a pilot motor. You may do it.

As described above, it is not essential for the present invention to use a magnetic pole position detecting sensor (PPS) such as a Hall element or a proximity switch. Instead of using these magnetic pole position detecting sensors directly, Using the induced voltage of the armature winding generated with the rotation of the rotor as the magnetic pole position signal of the rotor, indirectly extracting the magnetic pole position signal of the rotor,
The present invention can also be applied to a system using a BLDC motor without a magnetic pole position detector (PPSL: Pole Position Sensor Less) that performs operation control using this signal.

In the above description, the "rotating magnetic field type motor" of the type that generates a normal rotating magnetic field from the multi-phase AC winding has been described, but the present invention is not limited to this type.
The present invention can also be applied to different types of “magnetic pole concentrated winding type motor” and “excitation phase switching type motor”.

That is, as shown in FIG. 6 (a), in the conventional rotating magnetic field type motor, a coil is wound around a slot so that each phase winding of a multi-phase AC winding is overlapped on each magnetic pole. It is. In this case, the composite magnetic field or magnetomotive force distribution of the three-phase machine is substantially as shown in Expression 2.

[0033]

(Equation 2)

Where B ₀ is the combined magnetic flux of the gap, Ba, B
b and Bc are instantaneous values of magnetic flux components generated by the respective phases a, b and c,
ω ₀ is the rotation speed, t is time, and φ is the phase angle.

However, in the case of the magnetic pole concentrated winding method, as shown in FIG. 3B, each coil is wound independently so that the phase windings do not overlap each other on the magnetic poles of the iron core having the salient pole structure. The magnetomotive forces of the phase windings are not combined with each other. However, there is an advantage that the coil circumference can be reduced. In the magnetic pole concentrated winding type, since the synthetic magnetic flux Φ ₀ does not become a rotating magnetic field of a fixed value, even if a normal cage type rotor is inserted as a rotor, it does not rotate and no rotational force is obtained. However, when the rotor is a permanent magnet or a DC excitation magnet, the magnetic flux at each position in the circumferential direction is periodically changed, and the attracting / repelling force of the NS magnetic poles is utilized for the purpose of smooth rotation. Can be generated.

The VR type (Variable Reluctance Typ.)
e) The rotor of the motor also rotates as a synchronous motor according to substantially the same principle. However, since only a suction force is generated and no repulsive force can be expected, the rotation is not smooth. Further, even if the cage rotor is attached as described above, no rotational force is generated and the cage rotor does not rotate. A motor called a VR type stepping motor or an SR (Switched Reluctance Motor: trademark) motor or the like corresponds to this, and in general, driving by a square wave of the same polarity or a pulsating current is often performed without positive and negative AC excitation. In such a case, the expression “magnetic pole concentrated winding phase switching type” may be used.

FIG. 7 is a diagram showing an example of the iron core structure of these motors. The illustrated one is referred to as a 6/4 structure, and a pair of salient poles 82 of each of the six salient poles 82 of the stator 81 are symmetrical with each other.
Are in-phase, three-phase windings of u, v, w are wound. The rotor 82 has four salient poles 84. In general,
Assuming that the number of poles (number of teeth) of the stator 81 is N1 and the number of poles (number of teeth) of the rotor 83 is N2, these motors have N1 ± 2.
= N2. These motors can also be used as synchronous motors including the pilot motor of the present invention.

FIG. 8 is a diagram showing typical operating characteristics of a synchronous motor, which is called a "V curve". The vertical axis is the armature current I, and the horizontal axis is the exciting current If or the applied voltage V.
The solid line (V curve below 0'-n ') shows the actual motor operating range. The dotted V curve above 0'-n 'is
This shows an unstable region. Strictly speaking, the horizontal axis represents If
Is different from the case where the applied voltage V is applied, but the shapes are almost the same, so they are referred to as V curves without distinction. In this graph, the solid line 0-n connects the bottoms of the V curves and is the point where the armature current is the minimum, indicating the condition where the power factor is almost 100%. The left side of this vertical 0-n line is the lag power factor region,
The right side is the operation area of the advance power factor area.

A normal BLDC motor detects the magnetic pole position and operates under the torque angle condition (θ = δ = 90 °, cosψ = 1.0), that is, on the 0-n line in FIG. As the distance from the 0-n line increases, cosψ <1.0, and the driving power factor sharply decreases.

FIG. 9 shows the torque curve of the electric motor. The vertical axis represents the generated torque, and the horizontal axis represents the center of the rotor magnetic pole and the center position of the magnetomotive force generated by the stator armature current (center position of the rotating magnetic field).
Are shown. When the torque angle is 0,
The point is that the magnetic poles of the stator and the rotor under the no-load condition are attracted and in a balanced state. FIG. 9 shows an example of a non-salient pole machine. When the phase angle (torque angle) = 0, the generated torque becomes zero, and the generated torque increases in a sine (wave) function as the phase angle (θ = δ) increases. However, the maximum value is shown when θ = 90 °, and the generated torque is reduced at a phase angle larger than θ. Where φ
Is the phase angle between the terminal voltage and the current of the motor, the relationship between the torque angle θ and the power factor ψ is as shown in FIG.

FIG. 9 also shows a change in the torque curve when the applied voltage V is changed. The solid line is the torque curve under the condition of the rated voltage or less, and the dotted line is the torque curve under the condition of exceeding the rated voltage. The generated torque increases and decreases substantially in proportion to the square of the voltage as the applied voltage increases and decreases. When these relationships are expressed by mathematical formulas, the following Expression 3 is obtained.

[0042]

(Equation 3)

Here, Pin and Pout are input and output, and V
As shown in FIG. 10, a and Ea are terminal voltages and internal induced voltages of the motor, and Xs is a synchronous reactance.

Under the same applied voltage, as shown in the torque curve of FIG. 9, the generated torque changes almost sinusoidally with respect to the torque angle. Therefore, in this figure, the maximum load torque is Tmax when the torque angle δ = 90 °, and the motor cannot withstand a load torque greater than this, and the torque angle advances and loses synchronism. In general, a synchronous machine (generator or motor) cannot operate stably in this Tmax state and loses synchronism due to vibration or resonance due to a sudden change in load. That is, usually, it is necessary to operate within a safe range with an allowance for the torque angle or the maximum generated torque value (Tmax). This safe range has a torque angle of 45
About 60 °. To achieve this, the load torque must be
It is necessary to operate with a margin of about 13.5%.
However, this is an average value (steady state).

[0045]

As described above, according to the present invention, even in a system provided with a large number of synchronous motors, only a part of the synchronous motors is provided with a control circuit for controlling the magnetic pole position detecting means and the power converting means. Since it is not necessary to provide these for other synchronous motors, it is possible to reduce the overall cost while securing the reliability of the system. Can be prevented from affecting the operation of other synchronous motors, so that, for example, the operation state of the air conditioning system can be maintained as it is.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a synchronous motor group operation control system according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an example of a pilot motor used in the system.

FIG. 3 is a diagram illustrating an example of a rotor of a synchronous motor.

FIG. 4 is a circuit block diagram of a pilot motor and a power circuit unit.

FIG. 5 is a sectional view of a synchronous motor according to another embodiment of the present invention.

FIG. 6 is a diagram for explaining a distributed winding and magnetic pole concentrated winding motor to which the present invention is applied.

FIG. 7 is a cross-sectional view of a stator and a rotor of the motor having the same magnetic pole concentrated winding.

FIG. 8 is a diagram showing a V-curve showing a typical operation characteristic of the synchronous motor.

FIG. 9 is a diagram showing a torque curve for each applied voltage of the synchronous motor.

FIG. 10 is an equivalent circuit diagram and a vector diagram of the synchronous motor.

FIG. 11 is a block diagram showing a configuration of a conventional group operation control system for a BLDC motor.

[Explanation of symbols]

1,101 ... AC commercial power lines, 2,102 ... rectifier circuit, 3 ... power circuit unit, 4 ... VVVF output lines, 5 ₁ to 5
n, 104 _{1 to} 104 n ... synchronous motor, 6,106 ₁ to 10
6n ... magnetic pole position detection sensor, 7 ... control circuit, 8 ₁ ~8n ...
Overcurrent detection / protection device, 9: display, 10: pilot motor, 103 _{1 to} 103 n: BLDC motor, 105 ₁ to
105n ... Inverter.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H021 AA06 BA06 BA21 CA04 CA07 DA02 DA06 EA07 EA18 3H045 AA06 AA09 AA16 AA26 BA19 BA42 CA08 CA21 DA02 DA07 EA34 5H572 AA10 BB10 CC05 DD03 DD05 EE04 FF01 HC08 H08B HC08 H08B MM02

Claims (4)

[Claims] 1. A group operation control method for a synchronous motor in which a plurality of synchronous motors are controlled at a variable speed by power conversion means, wherein a position of a magnetic pole of a rotor is detected and detected in a part of the plurality of synchronous motors. A pilot motor for controlling the output voltage and output frequency of the power conversion means so that the phase angle between the magnetic pole position of the motor and the periodically changing magnetic field generated by the stator winding falls within a predetermined range. By supplying the output power of the power conversion means to the plurality of synchronous motors in common, the plurality of synchronous motors are controlled so as to be operated at the same speed. When an operation error occurs, the power supply to the synchronous motor where the operation error occurred is stopped, and the operation of other synchronous motors is continued. Group operation control method of the synchronous motor, characterized. 2. The group operation control method for synchronous motors according to claim 1, wherein the plurality of synchronous motors are of the same type and are of the same type with substantially the same load. 3. A plurality of synchronous motors, a part of these synchronous motors, and a magnetic pole position of the rotor detected by magnetic pole position detecting means for detecting a magnetic pole position of the rotor, and a stator winding. A pilot motor for controlling an output voltage and an output frequency so that a phase angle between the magnetic field and the periodically generated magnetic field falls within a predetermined range; and an output power whose output voltage and output frequency are controlled by the pilot motor. Power conversion means for supplying power to a plurality of synchronous motors in common; provided in each of the power supply paths to the plurality of synchronous motors, when an operation abnormality occurs in the synchronous motor, detecting this, Synchronous motor group operation control system, comprising: abnormality detection protection means for stopping power supply to the motor. 4. The synchronous motor according to claim 2, further comprising a display unit for identifying and displaying the synchronous motor in which the operation abnormality has occurred when the abnormality detection protection unit detects an operation abnormality. Group operation control system.