JP2008118801A - Control method for sensorless permanent magnet synchronous motor (pmsm) - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method capable of assuring the synchronous start of at least two sensorless PMSMs by one inverter device, preventing oscillation generation during stable rated operation and low speed rotation, and controlling safe stop in case of failure. <P>SOLUTION: This synchronous start method provides for at least two sensorless permanent magnet synchronous motors (PMSM) which use a three-phase alternate power source as power. The three-phase alternate current with ultra-low frequency is temporarily applied to at least two PMSMs by one inverter device for a certain period to ensure that the motors can be synchronously started with low rotation, then their rotational speeds can be raised by gradually increasing the frequency of the power source to reach the rated rotation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control method of a sensorless permanent magnet synchronous motor (hereinafter referred to as PMSM), more specifically, two or more sensorless PMSMs are synchronously started by a single inverter device at a rated speed. Sensorless PMSM control method that enables continuous operation, starting from the reverse rotation state, preventing vibrations, etc. that occur during rotation operation at a speed lower than the rated value, and stopping safely when a failure occurs It is about.

  Conventionally, a PMSM that uses a three-phase alternating current as a power source is equipped with a sensor (position detection device) that detects the position of the magnetic pole of the rotor, and detects the position of the magnetic pole of the rotor using this sensor. Depending on the position, a starting method is adopted in which a current is passed through each phase of the stator winding to generate a rotating magnetic field, torque is generated by interaction with the magnetic field generated from the magnetic pole, and power is transmitted to the load. Yes.

The total cost of such a PMSM with a sensor, a control circuit, and an inverter device is considerably higher than the total cost of an induction motor and an inverter device, which is a typical example of an AC motor, and there is also a problem that a failure occurs in the sensor. For this reason, for example, a PMSM of a sensorless type in which the cost is reduced by eliminating a sensor is used in a PMSM used under conditions of a certain rotational speed or more such as a blower fan. In this sensorless PMSM, in order to keep the control during continuous operation at the same level as that with a sensor, various data appearing at the stator winding terminals are detected, and the characteristics are calculated and controlled in a complicated manner. (For example, refer to JP-A-2001-268974 and JP-A-2002-272195).
JP 2001-268974 A JP 2002-272195 A

  However, when starting the sensorless PMSM by the conventional method, a separate special control device for starting is required or it is necessary to control from the start by further complicated the control method. As a result, there has been a problem that starting may fail. In addition, there is a problem that one inverter device for supplying power is required for each PMSM, which hinders cost reduction.

  The present invention is a synchronous start method of two or more sensorless PMSMs powered by a three-phase AC power source, and an ultra-low frequency three-phase AC current is applied to the two or more PMSMs from a single inverter device. After applying for a certain period of time and synchronously starting at a low speed, the frequency of the power supply is gradually increased to increase the rotational speed and reach the rated speed. The problem was solved by making sure that the system was started.

  The present invention enables a simple control method to control two or more sensorless PMSMs from a synchronous start to a continuous operation with a single inverter device, so that a significant cost reduction can be achieved. Arise.

  There is an effect that a sensorless PMSM including two or more units can be started from a reverse rotation state.

  This produces an effect that stable and quiet low-speed operation can be realized by preventing vibrations and the like from rotating at a lower speed than the rated rotation of the sensorless PMSM.

  It produces the effect that it can be safely stopped by detecting and controlling the abnormal rotation state due to failure of sensorless PMSM etc.

The present invention is a synchronous start method of two or more sensorless PMSMs powered by a three-phase AC power source, and an ultra-low frequency three-phase AC current is applied to the two or more PMSMs from a single inverter device. After applying for a certain period of time and synchronously starting at low rotation, the frequency of the power supply is gradually increased to increase the rotation speed and reach the rated rotation, so that two or more PMSMs can be achieved by a single inverter device. Was made to start reliably.
Alternatively, the rotor magnetic poles are attracted by applying a direct current from the inverter device to any two of the three or more PMSM three-phase windings to create a stator magnetic axis, and two or more After the PMSMs were synchronized at the same time, the frequency of the three-phase AC voltage was gradually increased to reach the rated rotation so as to start synchronously.
When the PMSM is rotating in reverse due to an external cause, the three-phase windings of two or more PMSMs are connected for each phase, and an electric braking current is generated between the PMSMs to reverse all PMSMs. By synchronizing to the same rotation speed in the state of rotation, detecting the voltage / frequency of PMSM generated at the synchronized rotation speed, and applying the voltage / current of the frequency of the angular speed ± allowable angular speed from the inverter device After being synchronized with the power supply, it is switched to a rotating magnetic field in the positive rotation direction so that the synchronous rotation is started so as to reach the rated rotation across the stop state.
When operating in a state where the rotational speed of two or more PMSMs during synchronous operation is reduced and the load torque is reduced, the generated voltage, frequency and current value are detected on the output side of the IGBT circuit of the inverter device, and the inverter device The phase of the current to be supplied is advanced by 15 ° or more from the voltage generated by the PMSM, and the internal phase difference angle δ is increased so that two or more PMSMs can be operated without causing vibration, turbulence, step-out, etc. It was.
The frequency, voltage and current generated corresponding to the rotation speed of the PMSM are detected by the IGBT circuit of the inverter device, and the voltage and current of the different frequency generated from the PMSM where the abnormality has occurred are detected by the IGBT circuit to synchronize. The IGBT circuit detects an abnormal frequency current that occurs when one of the two or more PMSMs in operation is out of the synchronous speed due to a failure or the like and the rotational speed decreases, and the output of the inverter device And the PMSM rotation is stopped safely.

The synchronous start method is one of the methods for starting a synchronous motor powered by a three-phase AC power source. As shown in FIG. 6, the synchronous generator G on the driving side and the synchronous motor M on the driven side are synchronized. When the machine is stopped, the three-phase terminals of the two are connected to each other and the excitation currents are made to flow. When the drive machine D directly connected to the synchronous generator G is slowly rotated at the start, the synchronous generator G By rotating and supplying a very low frequency current to the synchronous motor M, the synchronous motor M is synchronized with the synchronous motor G by the action of the rotating magnetic field generated on the synchronous motor M side and the magnetic field generated by the excitation current, and thereafter In this method, the rotation on the side of the synchronous motor G is increased, and the rotation continues to increase while being synchronized and is increased to a high rated rotation speed.
Such a synchronous start system is used to start a large capacity synchronous motor, for example, a generator motor directly connected to a pump turbine of a pumped storage power plant, or a large capacity turbine generator. This method is used as a method that can start smoothly without applying a large load, and detailed analysis is performed in various practical examples to confirm the possible range of synchronous starting with various parameters.

When the synchronous start method is to be applied to the PMSM, the output of the PMSM is 100 W to several kW first, so it has a very small capacity compared to the general motor, and the resistance value R of the armature winding. Is 0.04 to 0.2 pu (4 to 20%) in the unit method, and because the excitation is a permanent magnet, the PMSM excitation E ₂ is a fixed and constant value, and the power supply is synchronized. There is a difference in that an inverter power supply using an IGBT (Insulated Gate Bipolar Transistor) circuit or the like instead of the generator G is used. Since the detailed calculation for these is very complicated, the rotational speed N ₁ (or angular speed ω ₁ ) within which the synchronous start is possible by a simple calculation that omits parameters that have little influence from the parameters that have been clarified. Asked. It is assumed that the power of ω ₁ is applied to PMSM for a certain time from the inverter device.

1) In the case of 1C1M (starting one PMSM with one inverter device) (a) Circuit and current FIG. 1 shows an angular velocity ω ₁ (unit method) corresponding to a very low frequency f ₁ from the power source (inverter device). This shows a state where a voltage of 0.01 order) is being supplied to the PMSM.
When V ₀ is the rated phase voltage, the rated current is I ₀ (A), and f ₀ is the rated frequency, the voltage V when rotating at N ₁ min ^-1 at ultra-low speed is
V = V ₀ · (f ₁ / f ₀ ) = V ₀ · (ω ₁ / ω ₀ ) (1)
Here, Lm is an inductance corresponding to the reactance of the motor.
The impedance _{Z m} of the circuit, omega ₁ Lm is very small compared with Rm,

The current I ₁ (A) flowing through the circuit of FIG. 1 is I ₁ ≈V / Rm = V ₀ · (ω ₁ / ω ₀ ) · (1 / Rm) (3)
If the resistance of the power supply is ignored, Rm becomes the resistance of PMSM.

(B) Calculation of torque (a) F ₀ generated when the synchronous machine is rated is expressed by the following formula: F ₀ = 0.707 · Bm ₁ · A ₁ · Kw · cos δ [N / m ² ] (4 )
Bm ₁ ; Crest value of fundamental wave magnetic flux density [T] among magnetic fluxes generated by permanent magnets
A ₁ : Electric loading by armature winding A ₁ = (I ₀ · ΣZ) / (πD) (A / m)
It is represented by (ΣZ is the number of all series conductors of the three-phase winding, D is the inner diameter of the stator (m))
Kw: Winding coefficient, δ: Internal phase difference angle cos δ≈1.

An approximate value of F ₀ can be obtained by putting a numerical value applied in the case of a PMSM of several hundred W class into the above equation (4).
F ₀ ≒ 0.707 ・ 0.3 ・ 10 ⁴・ 1.0 ・ 1.0 ＝ 0.212 ・ 10 ⁴ [N / m ² ] ・ ・ ・ （5）
On the other hand, I ₁ is calculated for two specific types of PMSM (200 W and 150 W output).
200W; resistance of one phase Rm = 7Ω
150W; resistance of one phase Rm = 20Ω
Since the terminal voltage of the phase voltage of the above equation (3) is 200V,
V ₀ = 200 / √3 = 115.5 V (6)
I ₁ is obtained for each of ω ₁ / ω ₀ = 0.005, 0.01, 0.02, 0.03, and 0.06 (pu).

(B) Generated torque of 200W machine Rated current of 200W machine I ₀ = 1.0 (A), Surface area of rotor S = 0.01 (m ² ), Rated rotation speed N ₀ = 1300min ⁻¹ , Rotor radius r = 0.033m Therefore, the force F ₁ and the generated torque T of the entire PMSM are calculated using the above equation (5).
F ₁ = F ₀ · (I ₁ /1.0)·S[N], T = F ₁ · r [Nm] (7)

(C) Generated torque of 150W machine Rated current of 150W machine I ₁ = 0.7 (A), rotor surface area S = 0.008 (m ² ), rated rotational speed N ₀ = 1300min ⁻¹ , rotor radius r = 0.0285m , F ₁ and T can be calculated similarly.

3) energy and torque rotating body required to GD ² has a flywheel effect of GD ² (kgm ^2), the energy E ₀ held when rotating at a rotational speed of N ₀ (min ^-1), the
^{_{E 0 = 1.37 · GD 2 ·}} (N 0/1000) 2 (kWS)
= (1/730) · GD ² · N ₀ ² (WS or J) (8)
GD ² is assumed that the fan GD ² which is the load of PMSM is much larger than PMSM, and the same 200 W machine and 150 W machine are used.
GD ² = 0.124 [kgm ² ]
Therefore, E ₀ = (1/730) · 0.124 · 1300 ² = 287 (WS or J) (9)
The energy E held at the rotational speed of ω ₁ / ω ₀ is
E = E ₀ · (ω ₁ / ω ₀ ) ² (WS or J) (10)
On the other hand, when a three-phase current flows through the stator winding (low frequency of ω ₁ / ω ₀ ) and a slow rotating magnetic field is generated, N and S magnetic fields magnetized on the surface of the rotor by this magnetic field A force is generated between the two, and synchronization is impossible unless the first N and S poles are synchronized.
If the rotor magnetic pole has an 8-pole configuration, the mechanical angle θ ₁ per pole is
θ ₁ = 2π / 8 = 0.785 [rad] (11)
If the torque required to move the rotor θ ₁ is Tm, the energy W required for it is
W = Tm · θ ₁ [Nm or J] = 0.785 · Tm (12)
If (10) = (12) above,
W = 287 · (ω ₁ / ω ₀ ) ² = 0.785 · Tm (13)
Therefore, Tm = 365 · (ω ₁ / ω ₀ ) ² (14)
The required Tm for the 200 W machine is compared with the generated torque T obtained in (b).

From this calculation result, it can be seen that if the value of (ω ₁ / ω ₀ ) is about 0.03 pu (that is, 3%) or less, synchronization is achieved, and if it is more than that, synchronization is difficult.

  Similarly, the calculation is performed for the 150 W machine.

From this calculation result, it can be seen that synchronization is difficult even when the value of ω ₁ / ω ₀ is about 0.01 pu (ie, 1%).

4) Conditions under which synchronous start is possible Based on the above calculation results, conditions under which synchronous start is possible are that a voltage of a certain low frequency (corresponding to ω ₁ ) is applied to the PMSM from the power source and supplied to the PMSM by the flowing current. It can be seen that the torque and energy produced can exceed the rotor energy required to reach ω ₁ including GD ² within a certain period and can be supplied with a margin.

In the above 200W machine, omega ₁ is if secure the omega ₁ within 0.03Pu (or 3%), it is possible to synchronize.
On the other hand, since ω ₁ of the 150 W machine is 0.01 pu (ie, 1%) or less and the synchronization range is narrow and stable synchronization is difficult, stable startup is possible by increasing the power supply voltage V in this case.
Therefore, in order to synchronize stably, methods such as reducing the resistance value of PMSM or increasing the power supply voltage within an allowable range can be considered, but these must be considered as [motor cost + inverter cost] = total cost. Don't be. Although it is important to determine whether it is better to increase the physique of PMSM to lower the resistance value or to provide a margin for the inverter device, it may be selected according to the use conditions and the like.
The above example is for 1C1M (starting one PMSM with one inverter device), and for 1CXM (starting two or more PMSMs with one inverter device) As the problem is added, further margin is required.

  According to the starting methods shown in the above 1) to 4), the PMSM does not require a sensor (sensorless), and the voltage / current of the output frequency of the three-phase inverter device is in a low frequency state (several percent or less, mainly 3% or less), if applied to the PMSM for a fixed time of several seconds, it becomes possible to synchronize with two or more PMSMs as shown in FIG. 2, and then increase the power frequency of the inverter device to increase the speed. Thus, it can be increased while being synchronized up to the rated rotational speed.

  Next, a second embodiment of the synchronous start method will be described. As shown in FIG. 3, among the three-phase windings, a DC current is first passed through the two-phase windings (between UV in the figure), and the rotor magnetic poles are attracted by the stator magnetic axis (not rotating) generated thereby. Then, the magnetic axes are aligned and synchronized, and then the phase is switched between VW and WU as in a normal inverter device, and the frequency is increased. Also in this case, in order to align the first magnetic pole with the magnetic axis, a certain time Δt of several seconds (until the rotor is synchronized and stabilized while vibrating due to natural vibration) is required.

FIG. 3 is for one PMSM. When this method is applied to the start of two or more PMSMs, the synchronization condition is somewhat severe, but the PMSM resistance value GD ^2. Reliable synchronization can be achieved by examining the applied voltage. Which synchronous start method is selected in the first and second embodiments may be determined by examining the overall balance including the control method and the number of units.

When starting PMSM with 1CXM (X units with one inverter device), as described above, the most important factor for determining whether or not simultaneous starting is possible is the armature resistance value of PMSM, then GD ² , power supply Voltage affects. In other words, when two or more PMSMs are started at the same time, there is a margin in their resistance values, and the starting current (synchronous) is maintained by slowly maintaining the voltage and frequency (low voltage, low frequency) supplied by the inverter device and its holding period. Current) flows into the PMSM, and in the case of two, it is important to start the two simultaneously and synchronize completely. If this synchronization is completely implemented, in the process of further increasing the power supply frequency and increasing the rotational speed of the PMSM, the synchronization force acts on each other, so that it rises stably. The operation control after the ascending process and reaching the rated rotational speed can be stably operated by switching to closed loop control based on detection of voltage and frequency of PMSM. Since two or more PMSMs can be reliably started by a single inverter device, the overall cost including the cost of the sensorless PMSM can be greatly reduced.

When the sensorless PMSM is used in, for example, a large air conditioner, the load directly connected to the PMSM is a blower fan, and a PMSM set (two or more PMSMs operated by a single inverter device) When the power is turned off to stop the air), pressure is applied to the air blower fan that has stopped due to the influence of the positive pressure environment created by the air blower fan during other operations, and the fan rotates in the reverse rotation opposite to normal. The rotational speed may reach 40% of the rated rotational speed.
The present invention proposes a method for reliably synchronizing with a single inverter power source and stably starting even in the case of two or more sensorless PMSMs in such a reverse rotation situation.

If the two blower fans are of different power sources (inverter devices for each unit), they rotate at different rotational speeds (for example, one is -N ₃ min ^-1 and the other is -N ₄ min ^-1 ). In the case of 1C1M, by connecting the windings of each phase of both PMSMs, dynamic braking occurs due to the current flowing between the two PMSMs caused by the reverse rotation, and the two PMSMs are connected to the respective rotations of the two PMSMs. It is possible to achieve a state of being synchronized at the same rotational speed of approximately -N ₅ min ⁻¹ , that is, two PMSMs can be regarded as one PMSM.
In this state, the voltage / frequency generated from the PMSM is detected, and a corresponding voltage is applied from the IGBT circuit to simultaneously synchronize the two PMSMs, and the rotation is -N ₅ min ^-1 (reverse rotation) to It can be increased from ₀ min ^-1 (stop) to N ₀ min ^-1 (rated rotational speed).

More specifically, in the case of two PMSMs (a) and (b) (1C2M), the three-phase terminals of both PMSMs are respectively connected to the output terminals from the IGBT circuit. Therefore, when the output of the IGBT circuit is turned off to stop this set for some reason, PMSM (a) (b) becomes N ₀ min ⁻¹ (rated speed) to ₀ min ⁻¹ (stop) to reverse rotation. Since the two machines are electrically connected, even if they rotate in the reverse direction, they remain synchronized and rotate at the same rotational speed of −N ₅ min ⁻¹ . If there is no connection between the two PMSMs, the PMSMs (a) and (b) have different rotation speeds of -N ₃ min ^-1 and -N ₄ min ^-1 due to differences in fan characteristics, etc. However, when electrically connected, the braking current flows, so the electric braking torque works, and the rotational speed of -N ₅ min ^-1 between -N ₃ min ^-1 and -N ₄ min ^-1 Will rotate in synchronization.
Therefore, the generated voltage and frequency of the PMSM at that time (PMSM acts as a generator) are detected from the power supply base, and the inverter device applies the three-phase voltage and frequency of the reverse rotating magnetic field corresponding to the voltage V ₅ to determine a predetermined value. The current can be made to synchronize with the power source, and then the two phases of the power source can be switched to produce a rotating magnetic field in the positive direction, thereby shifting to a state of 0 min ⁻¹ .

  In the above process, the sensorless PMSM can be started from the reverse rotation state. This is a great feature that it is possible not only with one PMSM but also with many PMSMs.

The synchronization phenomenon at the time of reverse rotation is almost similar to the synchronization phenomenon at the time of starting from 0 min ^-1 . As shown in FIG. 4, when the forward rotation direction is clockwise, the reverse rotation direction is counterclockwise. In the case of two PMSMs, a counter-rotating magnetic field that rotates at -N ₅ min ^-1 synchronously as described above is applied. since making the frequency f ₅ induced in the stator windings _{f 5 = PN 5/120 (} Hz) (P is the number of poles)
And
ω ₅ = 2πf ₅
Therefore, with respect to the angular velocity ω ₅ obtained from the frequency detected from the winding terminal, the power supply applied from the inverter device is synchronized within the range of angular velocity ω ₅ ± (0 to ω ₁ ) in the reverse rotating magnetic field. It turns out that is possible. ω ₁ is the synchronization allowable angular velocity. In practice, it is important to apply an angular velocity of ω ₅ ± Δω ₁ (Δω ₁ <ω ₁ ) to make synchronization easier and more reliable. Naturally, the applied voltage is a voltage that allows the current necessary for the synchronization described in 1) to flow. See vector in FIG.

FIG. 4B shows the direction of the current that generates the reverse rotating magnetic field of the output of the inverter device at the time of synchronization. Thus synchronization after is immediately return V as in FIG. 4 (c), the by interchanging W phase the rotational speed by changing the forward rotation field until 0min ^-1 from -N ₅ min ^-1. The above process can be performed easily and reliably even with a large number of PMSMs. For starting from 0 min ⁻¹ , the synchronous starting method described in 1) is applied.

In this embodiment, a control method will be described as a stabilization measure at a rotational speed of 70% or less of the rated rotational speed.
When the rotation speed is lower than the rated rotation speed, particularly in the case of a load such as a blower fan, the load torque decreases in proportion to the square of the rotation speed. Therefore, the current required by the PMSM is also reduced in proportion to the torque. This means that the internal phase difference angle δ of the PMSM becomes smaller. In the case of 1CXM, when two or more PMSMs are connected to one inverter power supply, the current value is greatly reduced. In some cases, vibrations caused by the difference in internal phase difference angle due to a slight difference in the fan fan load characteristics may occur, resulting in a phenomenon in which stable operation is not possible. Therefore, the voltage, frequency, and current values of two or more PMSMs in synchronous operation are detected at the output side of the IGBT (Insulated Gate Bipolar Transistor) circuit of the inverter device, and the phase of the current supplied from the inverter device is determined from the PMSM generated voltage. The current was increased by increasing the internal phase difference angle δ as a phase advance of 15 ° or more, and two or more PMSMs were operated without causing vibration, turbulence, step-out, etc.

In general, during rated operation (rated rotational speed), in order to operate PMSM most efficiently, direct axis current Id = 0 control (control in which the phase of the motor-generated voltage and current is in phase) is often employed. In this case, since the current becomes the minimum value, when two or more units are operated in parallel, there is a high possibility of vibration or turbulence when operating at a reduced rotational speed as described above. In order to improve this, if the phase angle of the current is advanced from the generated voltage, the internal phase difference angle δ increases to δ + Δδ and the current value also increases, so both PMSMs (in the case of two units) caused by the difference in load characteristics Effective current input / output is reduced by an increase in I ² R loss, etc., and vibration or turbulence can be suppressed. A stable suppression effect can be expected by setting the phase advance angle to 15 ° or more, preferably 20 ° or more.

In this embodiment, a method for safely stopping PMSM in the event of a failure will be described.
The voltage / current generated at the frequency corresponding to the rotational speed of the PMSM is detected by the IGBT circuit of the inverter device, and one of the two or more PMSMs in synchronous operation is out of synchronization due to failure or the like. The current of a different frequency generated when the rotational speed is reduced is detected by the IGBT circuit, the output of the inverter device is shut off, and the rotation of the other healthy PMSM is safely stopped.
For example, when two PMSMs are operating, if one of them falls out of the synchronous speed due to bearing damage or the like and the rotational speed decreases toward the stop, PMSM generates a voltage with a frequency corresponding to the rotational speed, Since the current flows to the IGBT circuit of the inverter device and another unit as a current of a different frequency, if this current is detected at the output side of the IGBT circuit and the output of the inverter device is turned off, this set can be safely stopped. Will be able to. Note that if one of the malfunctioning machines is completely stopped early, a large current flows from the IGBT circuit, so that it can be stopped by an OCR (Over Current Relay) circuit.

  The control method of the present invention is reliable and easy to configure in an environment where two or more sensorless PMSMs are used, and can be widely used with the advantage of cost reduction.

Example of equivalent circuit at start-up in 1C1M Circuit example in 1CXM Principle diagram of the synchronous start method of the second embodiment Principle of synchronization during reverse rotation Vector diagram of voltage applied during reverse rotation Principle of synchronous start method

Claims (5)

  A synchronous start method of two or more sensorless permanent magnet synchronous motors (PMSM) powered by a three-phase AC power source, and the two or more PMSMs have a three-phase AC that is ultra-low frequency than a single inverter device. Two or more three-phase alternating currents characterized in that after applying a current for a certain period of time and synchronously starting at low rotation, the frequency of the power supply is gradually increased to increase the rotation speed and reach the rated rotation A synchronous start method for a sensorless permanent magnet motor powered by a power source.   The rotor magnetic poles are attracted by applying a direct current from the inverter device to any two-phase winding of each of the three or more PMSM three-phase windings to form a stator magnetic axis, 2. The synchronous start method for a sensorless permanent magnet synchronous motor according to claim 1, wherein the PMSM is simultaneously synchronized, and then the frequency of the three-phase AC voltage is gradually increased to reach the rated rotation.   By connecting two or more PMSM three-phase windings for each phase and generating an electric braking current between the PMSMs, all PMSMs are synchronized to the same rotational speed in the reverse rotation state, The PMSM generated voltage and frequency at the synchronized rotational speed are detected, and the voltage and current of the angular speed ± permissible angular speed are applied from the inverter device to synchronize with the power source. The synchronous start method of the sensorless permanent magnet synchronous motor from the reverse rotation state that reaches the rated rotation across the stop state by switching to   When operating with the load torque reduced by reducing the rotational speed of two or more PMSMs in synchronous operation, the generated voltage, frequency and current values are output on the IGBT (Insulated Gate Bipolar Transistor) circuit side of the inverter. The phase of the current supplied from the inverter device is advanced by 15 ° or more from the voltage generated by the PMSM, and the internal phase difference angle δ is increased, so that two or more PMSMs can be vibrated, turbulent or step out. A method for operating a sensorless permanent magnet synchronous motor that is operated without being generated.   The frequency, voltage and current generated corresponding to the rotation speed of the PMSM are detected by the IGBT circuit of the inverter device, and the voltage and current of the different frequency generated from the PMSM where the abnormality has occurred are detected by the IGBT circuit to synchronize. The IGBT circuit detects an abnormal frequency current that occurs when one of the two or more PMSMs in operation is out of the synchronous speed due to a failure or the like and the rotational speed decreases, and the output of the inverter device Is a sensorless permanent-magnet synchronous motor that safely shuts down PMSM rotation.

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