JP2004064902A - Synchronous motor control device and equipment using it - Google Patents

Abstract

A good synchronous motor control device that suppresses an increase in current at the time of motor out-of-step and detects stop of out-of-step is provided.
A control device for a synchronous motor according to the present invention calculates an excitation current from a motor current detected by current detection means, and outputs an output voltage of an inverter circuit to a motor power generation constant, an excitation current command, and the excitation current. In addition to determining the voltage command, a voltage correction amount is created so that the excitation current command matches the excitation current, and the voltage correction amount is compared with a predetermined value to quickly step out of the synchronous motor. To be detected.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device that controls the rotation speed of a permanent magnet synchronous motor to a desired rotation speed, and an air conditioner, a refrigerator, and a vacuum cleaner using the control device.
[0002]
[Prior art]
Synchronous motors, especially permanent magnet synchronous motors combining permanent magnet rotors and stator windings, are maintenance-free and have been used in air conditioners, refrigerators, washing machines and the like. In the drive control of the permanent magnet synchronous motor, it is necessary to control the position of the magnetic pole of the rotor and the position of the stator winding to be energized closely. In a motor for a compressor such as an air conditioner, the motor and the compressor are housed in the same housing, and the temperature condition is severe. For this reason, a rotor position detection sensor such as a Hall element cannot be built in the motor. Therefore, a position sensorless driving method of estimating the magnetic pole position of the rotor and driving the motor is used.
[0003]
However, in the above-described position sensorless driving method, the magnetic pole position of the rotor is not directly detected, so that when the load of the motor suddenly changes, the motor may step out and stop.
[0004]
Japanese Patent Application Laid-Open No. 2001-25282 discloses a step-out detection device that compares a period of a reactive current and a period of a voltage when step-out is stopped to determine step-out.
[0005]
[Problems to be solved by the invention]
In the related art, when the motor loses synchronism, the reactive current increases. That is, during motor control and during normal operation, the applied voltage is determined in consideration of the induced voltage generated during motor rotation. However, when the motor stops synchronizing due to a sudden change in the load or the like, the control method of the related art considers that the induced voltage is generated even though the motor is stopped and the induced voltage is not generated. As a result, the exciting current, which is a reactive current, increases, and as a result, the motor current increases, and the motor and the power element generate heat.
[0006]
An object of the present invention is to provide a synchronous motor control device that detects a step-out stop by suppressing an increase in current at the time of motor step-out.
[0007]
[Means for Solving the Problems]
The synchronous motor control device of the present invention calculates the exciting current from the motor current detected by the current detecting means, and outputs the output voltage of the inverter circuit using the motor constant set value, the exciting current command, and the exciting current. A command is determined, a voltage correction amount is created so that the excitation current command matches the excitation current, and the voltage correction amount is compared with a predetermined value to immediately detect a step-out of the synchronous motor.
[0008]
The synchronous motor control device of the present invention selects a motor power generation constant as the above-mentioned motor constant set value, and corrects the motor power generation constant set value to correct the voltage command.
[0009]
As the motor current, a DC current flowing from the DC power supply to the inverter circuit is detected, and the motor current is detected from the DC current.
[0010]
The synchronous motor control module according to the present invention includes, in a package, an inverter circuit that drives a synchronous motor by converting a DC voltage into a three-phase AC voltage, a control circuit that performs control processing according to a command speed, and drives the inverter circuit. A control circuit for calculating an exciting current from a motor current, an exciting current command generating means, an output voltage of an inverter circuit, a motor constant set value, an exciting current command, and the exciting current. And a voltage command generator that determines a voltage correction amount so that the excitation current command matches the excitation current, and the voltage correction amount and a predetermined value set in advance. The step out of the synchronous motor is detected by comparison.
[0011]
Further, the synchronous motors of the air conditioner, refrigerator, washing machine, and vacuum cleaner are driven by the motor control device having the step-out detection function.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a synchronous motor control device of the present invention and a device using a synchronous motor driven by the control device will be described with reference to FIGS. 1 to 9.
[0013]
(Example 1)
FIG. 1 is a block diagram of the synchronous motor control device of the present embodiment. The synchronous motor 3 of the present embodiment is a synchronous motor having a permanent magnet as a rotor (hereinafter abbreviated as a permanent magnet synchronous motor). The synchronous motor control device according to the present embodiment converts the voltage of the DC power supply 1 into a three-phase AC voltage, supplies the three-phase AC voltage to the stator winding of the synchronous motor 3, and rotates the synchronous motor 3; A control circuit 4 for controlling the synchronous motor 3 according to the control signal, a driver 5 for driving the inverter circuit 2 in accordance with the control circuit 4, and a resistor 6 for detecting a direct current.
[0014]
The inverter circuit 2 converts the voltage of the DC power supply 1 into a three-phase AC voltage using a power semiconductor switching element such as an IGBT, a power MOSFET, or a bipolar power transistor.
[0015]
The control circuit 4 is a one-chip microcomputer or a hybrid IC. As shown in FIG. 1, the control circuit 4 outputs motor current information based on a detection voltage 6a generated at both ends of the resistor 6. Unit 7, a coordinate converter 8 for converting the three-phase motor current information 7a into an exciting current Idc and a torque current Iqc, which are current values on the dq coordinate axis, and an exciting current command generator for creating an exciting current command value Id ^* . 9, a torque current command generator 10 for generating a torque current command Iq ^* from the torque current Iqc, a motor constant setter 11 for setting a power generation constant set value Ke ^* and another motor constant set value group 11a, and an exciting current. create a corrected EMF constant ^{Ke **} from the exciting current command value Id ^* and the generator constant setting value Ke ^* Idc, also EMF constant set value Ke ^* and corrected EMF constant Ke ^* A back EMF constant correction operation and the step-out detector 12 outputs a PWM signal output stop signal 12a for blocking the PWM signal 15a to detect the out-of-step from a, the command speed ω and the other motor constant setting value group 11a and the torque A motor applied voltage generator 13 for outputting a d-axis voltage command Vdc ^* and a q-axis voltage command Vqc ^* from the current command Iq ^* , the excitation current command Id ^*, and the corrected power generation constant Ke ^** ; A dq inverse converter 14 for performing coordinate conversion from the command Vdc ^* and the q-axis voltage command Vqc ^* to a three-phase voltage command 14a; a PWM signal generator 15 for generating a PWM signal 15a from the three-phase voltage command 14a and outputting it to the driver 5; It has.
[0016]
Next, a description will be given of a power generation constant correction calculation and step-out detector 12, which is a main part of the present invention and is a voltage command correction means. FIG. 2 is a block diagram of the power generation constant correction calculation and step-out detector 12. The power generation constant correction calculation and out-of-step detector 12 includes a power generation constant correction value calculation unit 21 that calculates a power generation constant correction value ΔKe based on a difference 20a between the excitation current command value Id ^* and the excitation current Idc, and a power generation constant set value. Ke ^* and EMF constant correction value by adding the ΔKe seeking corrected EMF constant Ke ^**, power generation constant setting value Ke ^* and corrected EMF constant Ke ^** compares the in out-determining out-of-step judging unit 23. If the step-out determination unit 23 determines that there is step-out, it outputs a PWM signal output stop signal 12a.
[0017]
Next, the principle of step-out detection of this embodiment will be described. The motor applied voltage is determined from the d-axis voltage command Vdc ^* and the q-axis voltage command Vqc ^* created by the motor applied voltage generator 13 in FIG. The d-axis voltage command Vdc ^* and the q-axis voltage command Vqc ^* include a resistance setting value R ^* , dq-axis inductance setting values Ld ^* and Lq ^* , an excitation current command Id ^*, and a torque current command Iq ^* . It is created from the command speed ω ^* and the corrected power generation constant Ke ^{** by the} formulas (1) and (2).
[0018]
Vdc ^* = R ^* · Id ^* −ω ^* · Lq ^* · Iq ^* (Equation 1)
Vqc ^* = R ^* · Iq ^* + ω ^* · Ld ^* · Id ^* + ω ^* · Ke ^** (Equation 2)
In the prior art, the q-axis voltage command Vqc ^* is obtained by Expression (3) using the power generation constant set value Ke ^* instead of the corrected power generation constant Ke ^** of Expression (2).
[0019]
Vqc ^* = R ^* · Iq ^* + ω ^* · Ld ^* · Id ^* + ω ^* · Ke ^* (Equation 3)
The motor voltage waveform of the prior art, which is controlled by using the equation (2), the motor current waveform during normal rotation of the motor, the excitation current waveform during normal rotation, and the time when the motor stops due to step-out. FIG. 3 shows the motor current and the exciting current when the motor stops due to step-out.
[0020]
When the motor is stopped, the command speed ω ^* in the above-described equations (1) and (2) becomes 0, and the voltages shown in the following equations (4) and (5) should be used. Directive is required.
[0021]
Vdc ^* = R ^* · Id ^* (Equation 4)
Vqc ^* = R ^* · Iq ^* (Equation 5)
If a voltage command value is created by the above-described equations (1) and (2) without detecting step-out, the non-zero command speed ω ^* is used in the equations (1) and (2). Even if the motor stops, the same voltage command as during operation is created. On the other hand, the excitation current command Id ^* is almost zero because it is created from the detected torque current Iq. As a result, the voltage becomes excessively large by ω ^* · Ke ^{** in the} formula (1) and the motor current increases, so that the d-axis voltage command Vdc ^* and the q-axis voltage command are substantially obtained. Vqc ^* is as shown in the following Expression (6) and Expression (7).
[0022]
Vdc ^* = R ^* · Id ^* (Equation 6)
Vqc ^* = ω ^* · Ld ^* · Id ^* + ω ^* · Ke ^* (Equation 7)
As a result, the q-axis voltage command Vqc ^* has an unnecessarily large value in the positive direction, so that the exciting current Idc largely flows in the positive direction.
[0023]
In the present invention, step-out is detected quickly, and when step-out occurs, the voltage is lowered to lower the current. This will be described with reference to FIGS. First, in order to lower the voltage, reducing the product of the equation 2 with the q-axis voltage command Vqc ^* a form to which the command speed omega ^* and the generator constant setting value Ke ^*. For this purpose, a power generation constant correction value ΔKe is created so that the excitation current command value Id ^* and the excitation current Idc match, and then a corrected power generation constant that is the sum of the power generation constant set value Ke ^* and the power generation constant correction value ΔKe The command speed ω ^* is multiplied by Ke ^** to form a q-axis voltage command Vqc ^* . As a result, at the time of step-out, the exciting current Idc increases in the positive direction, the power generation constant correction value ΔKe becomes negative, and the q-axis voltage command Vqc ^* decreases, so that the voltage command also decreases and the increase in current can be suppressed.
[0024]
On the other hand, since the corrected power generation constant Ke ^** is smaller than the power generation constant set value Ke ^* , in this embodiment, 0 is selected as the predetermined value, and the corrected power generation constant Ke ^** is compared with 0 to determine the correction. If the post-generation constant Ke ^** is close to zero, it is determined that the motor is out of synchronization and the PWM signal output stop signal 12a is output.
[0025]
Depending on the application of the motor, the rotor of the motor may slightly vibrate without stopping completely at the time of step-out. In such a case, since the corrected power generation constant Ke ^** does not become close to 0, the predetermined value to be compared is set to a value of 60% or less with respect to the power generation constant set value Ke ^* , preferably a value of 40% or less. I do.
[0026]
FIG. 4 shows a waveform of a motor applied voltage and a waveform of a motor current when the motor stops synchronizing in this embodiment. By correcting the power generation constant as shown in FIG. 4, the motor current at the time of step-out can be reduced, and after the detection of step-out, the PWM signal is cut off to make the motor current zero.
[0027]
In the above embodiment, the motor is controlled by obtaining the motor current information from the DC current flowing in the inverter circuit 2. However, the motor current information may be obtained directly from the motor winding.
[0028]
(Example 2)
FIG. 5 is a schematic diagram of a module 50 in which the inverter circuit 2, the control circuit 4, and the driver 5 (not shown) of the synchronous motor control device shown in the first embodiment are incorporated in one package. The lid on the top is omitted. In the module 50 of the present embodiment, the inverter circuit 2, the control circuit 4, and the driver 5 are housed in a substantially rectangular resin mold package having two sets of opposing sides. The control circuit 4 is mounted on another substrate, and is connected to the substrate on which the inverter circuit 2 and the driver 5 are mounted by lead wires. Further, a smoothing capacitor can be mounted on the lid on the upper surface of the module.
[0029]
On the bottom surface of the resin mold package, a metal heat radiating plate having good heat conductivity such as an aluminum alloy or a copper alloy is disposed via an electric insulating layer such as a resin or ceramic plate. On one side of the module, an output terminal portion 51 for connecting three cables for connecting the output of the inverter circuit 2 to the synchronous motor 3 is integrally molded with a resin mold package.
[0030]
A terminal for inputting the voltage of the DC power supply 1, a terminal for inputting the speed command, a power supply terminal for the control circuit 4 and the driver 5, and the like are arranged in a row on the side opposite to the side on which the output terminal portion is disposed. As shown in FIG. 5, a notch is provided between the input terminal 52 of the DC power supply and the terminal 53 for inputting the speed command and the control terminal 53 such as the power supply terminal of the control circuit 4 and the driver 5. It is a passage for electric wires connected to the connector provided inside the module. Although the resistor 6 for detecting a direct current is externally attached to the module 50 in FIG. 5, it may be built in the module 50.
[0031]
As described above, since the control circuit 4, the driver 5, and the inverter circuit 2 are built in the module, no noise enters the signal line from the control circuit 4 to the driver 5, and the motor stops synchronizing with a sudden change in load. However, the motor stop state can be determined without increasing the motor current, and the motor current can be stopped quickly based on the determination result.
[0032]
(Example 3)
FIG. 6 is a schematic diagram of an outdoor unit 60 of an air conditioner provided with a synchronous motor control device 60a including the control circuit 4 of the present invention as a drive source of a compressor. The air conditioner according to the present embodiment includes an outdoor unit including a compressor that compresses a refrigerant, and an indoor unit that adiabatically expands the compressed refrigerant to absorb heat, or that compresses the refrigerant to generate heat and radiates heat. In the present embodiment, the synchronous motor control device 60a is the module shown in the second embodiment.
[0033]
When the synchronous motor control device of the present invention is applied to a permanent magnet synchronous motor that is a driving source of a compressor, even when the motor loses synchronism due to a sudden change in load, the motor current does not increase and the motor stop state is determined. The motor current can be stopped based on this determination result, and good motor control can be realized. In addition, since the reactive current unrelated to the torque does not increase, a high-quality air conditioner with low loss can be realized. Furthermore, since the motor stop state can be determined, the capacity of the air conditioner can be quickly restored by restarting, and a high-performance air conditioner can be realized. In this embodiment, the first and second embodiments are applied to the operation control of the motor of the compressor. However, the first and second embodiments may be applied to a fan motor of an outdoor unit and a fan motor of an indoor unit. Needless to say. Further, instead of the module of the second embodiment, a printed wiring board on which individual components are mounted may be used.
[0034]
(Example 4)
FIG. 7 is a schematic diagram of a refrigerator 70 including a synchronous motor control device 70a including the control circuit 4 of the present invention as a drive source of a refrigerator compressor. Although not shown in FIG. 7, the refrigerator of the present embodiment includes a refrigerator compartment and a freezer compartment, and further includes a compressor, a condenser, a freezer compartment evaporator, and a refrigerator compartment evaporator. . In this embodiment, the compressor and the permanent magnet synchronous motor are housed in the same case, and the motor has no rotor position sensor. In the refrigerator of the present embodiment, the synchronous motor control device 70a is the module shown in the second embodiment.
[0035]
When the control device of the synchronous motor of the present invention is used as a drive source of a compressor for a refrigerator, it is possible to determine the motor stop state, and it is possible to quickly recover the capacity of the refrigerator by restarting, so that the internal temperature change It is possible to realize a refrigerator with less damage and less damage to foods and the like. Instead of the module of the second embodiment, a printed wiring board on which individual components are mounted may be used.
[0036]
(Example 5)
FIG. 8 shows a schematic diagram of a washing machine 80 in which the motor control device of the present invention is applied to a motor control device of a washing machine. The washing machine of the present embodiment includes a substantially cylindrical washing tub and dewatering tub, a stirring blade disposed at the bottom of the washing tub and dewatering tub, an outer tub containing the washing tub and dewatering tub, a stirring blade or a washing tub. A permanent magnet synchronous motor for rotating the tub / dehydration tub. In the washing machine of this embodiment, the synchronous motor control device 80a is the module shown in the second embodiment, and the module is arranged above the motor which is hardly wetted by water.
[0037]
When the control device for a synchronous motor of the present invention is used as a drive source of a washing machine, the motor stop state can be determined, so that the performance of the washing machine can be quickly restored by restarting, and the washing performance can be reduced without reducing the washing capacity. Can be continued.
[0038]
Instead of the module of the second embodiment, a printed wiring board on which individual components are mounted may be used.
[0039]
(Example 6)
FIG. 9 is a schematic diagram of a cleaner 90 provided with the synchronous motor control device 90a of the present invention as a drive source of the cleaner. The vacuum cleaner of the present embodiment includes a vacuum cleaner main body including a blower for sucking dust, a suction port for sucking dust, and a hose or a pipe portion communicating the suction port with the main body, and the blower is driven by a permanent magnet synchronous motor. Drive. In the vacuum cleaner of this embodiment, the module shown in Embodiment 2 was used as the synchronous motor control device 90a.
[0040]
When the control device for a synchronous motor of the present invention is applied to control of a motor of a vacuum cleaner, the motor current does not increase, so that a low-loss vacuum cleaner can be realized. In particular, a battery-driven vacuum cleaner having a secondary battery built in the main body. In this case, a vacuum cleaner that can be operated for a long time while suppressing the consumption of the secondary battery can be realized. Further, since the motor stop state can be determined, it is possible to realize a cleaner capable of quickly recovering its capacity as a cleaner by restarting.
[0041]
Instead of the module of the second embodiment, a printed wiring board on which individual components are mounted may be used.
[0042]
【The invention's effect】
According to the present invention, even at the time of motor out-of-synchronization stop due to a sudden change in load, the motor stop state can be determined without increasing the motor current, and the excitation current can be stopped based on the determination result.
[Brief description of the drawings]
FIG. 1 is a block diagram of a synchronous motor control device according to a first embodiment.
FIG. 2 is a block diagram of a power generation constant correction calculation and a step-out detector according to the first embodiment.
FIG. 3 is an explanatory diagram of a voltage / current waveform at the time of stopping out-of-step by control according to the related art.
FIG. 4 is an explanatory diagram of a power generation constant correction calculation and an operation of a step-out detector according to the first embodiment.
FIG. 5 is a schematic diagram of a synchronous motor control device module according to a second embodiment.
FIG. 6 is a schematic diagram of an air conditioner according to a third embodiment.
FIG. 7 is a schematic view of a refrigerator according to a fourth embodiment.
FIG. 8 is a schematic view of a washing machine according to a fifth embodiment.
FIG. 9 is a schematic view of a vacuum cleaner according to a sixth embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... DC power supply, 2 ... Inverter circuit, 3 ... Synchronous motor, 4 ... Control circuit, 5 ... Driver, 6 ... Resistor, 6a ... Detection voltage, 7 ... Motor current information reproduction part, 7a ... Motor current information, 8 ... Coordinate conversion unit, 9: excitation current command generator, 10: torque current command generator, 11: motor constant setting unit, 11a: motor constant setting value group, 12: power generation constant correction calculation and step-out detector, 12a: PWM Signal output stop signal, 13 ... motor applied voltage generator, 14 ... dq inverse converter, 14a ... 3-phase voltage command, 15 ... PWM signal generator, 15a ... PWM signal, 21 ... power generation constant correction value calculator, 23 ... Step-out determination unit, 50 module, 51 output terminal unit, 52 input terminal, 53 control terminal, etc. 60 outdoor unit of air conditioner, 60a, 70a, 80a, 90a synchronous motor control device, 70 refrigerator , 80 Washing machines, 90 ... vacuum cleaner, Idc ... the excitation current, Iqc ... torque current, Id * ^... the excitation current command value, Ke * ^... power generation constant setting value, ΔKe ... power generation constant correction value, Ke ^{** ...} correction after the power generation constant, Vdc ^* : d-axis voltage command, Vqc ^* : q-axis voltage command.

Claims (11)

An inverter circuit that converts a DC voltage into a three-phase AC voltage to drive a synchronous motor; a current detection unit that detects a current flowing through the synchronous motor; a control circuit that performs control processing according to a command speed; and drives the inverter circuit. In a control device for a synchronous motor including a driver,
The control circuit is a coordinate conversion means for calculating an exciting current from the motor current detected by the current detecting means, an exciting current command generating means, an output voltage of the inverter circuit, a motor constant set value, an exciting current command, Voltage command generating means for determining using the exciting current, and voltage command correcting means for creating a voltage correction amount so that the exciting current command and the exciting current coincide with each other. A synchronous motor control device for detecting step-out of the synchronous motor by comparing 2. The control device for a synchronous motor according to claim 1, wherein the motor constant setting value is a motor power generation constant setting value, and the voltage correction amount is a motor power generation constant correction value for correcting the motor power generation constant setting value. A control device for a synchronous motor, characterized in that: 3. The synchronous motor control device according to claim 2, wherein the current detecting means detects a DC current flowing from the DC power supply to the inverter circuit, and detects a motor current from the DC current. Control device. 3. The synchronous motor control device according to claim 2, wherein the motor power generation constant correction value as the voltage correction amount is 0 to 60% of the motor power generation constant set value. A synchronous motor control module including a package, an inverter circuit that converts a DC voltage into a three-phase AC voltage and drives a synchronous motor, a control circuit that performs control processing according to a command speed, and a driver that drives the inverter circuit. ,
The control circuit determines the coordinate conversion means for calculating the exciting current from the motor current, the exciting current command generating means, and the output voltage of the inverter circuit by using the motor constant set value, the exciting current command and the exciting current. Voltage command generating means for performing voltage synchronization, and a voltage command correcting means for generating a voltage correction amount such that the exciting current command matches the exciting current. A synchronous motor control module for detecting step-out of a motor. 6. The synchronous motor control module according to claim 5, wherein said control module includes a current detecting means for detecting a current flowing through the synchronous motor. 6. The synchronous motor control module according to claim 5, wherein the semiconductor switching element of the inverter circuit is an IGBT. In an air conditioner including an outdoor unit including a compressor that compresses a refrigerant and an indoor unit that adiabatically expands the compressed refrigerant,
A control device for the synchronous motor driving the compressor, an inverter circuit for converting the DC voltage into a three-phase AC voltage to drive the synchronous motor, current detecting means for detecting a current flowing through the synchronous motor, and controlling according to a command speed A control circuit that performs processing, and a driver that drives the inverter circuit;
The control circuit is a coordinate conversion means for calculating an exciting current from the motor current detected by the current detecting means, an exciting current command generating means, an output voltage of the inverter circuit, a motor constant set value, an exciting current command, Voltage command generating means for determining using the exciting current, and voltage command correcting means for creating a voltage correction amount so that the exciting current command and the exciting current coincide with each other. Wherein the step-out of the synchronous motor is detected by comparing In a refrigerator including a refrigerator compartment, a freezer compartment, a compressor that compresses a refrigerant, a condenser, a freezer compartment evaporator, and a refrigerator compartment evaporator,
A control device for the synchronous motor driving the compressor, an inverter circuit for converting the DC voltage into a three-phase AC voltage to drive the synchronous motor, current detecting means for detecting a current flowing through the synchronous motor, and controlling according to a command speed A control circuit that performs processing, and a driver that drives the inverter circuit;
The control circuit is a coordinate conversion means for calculating an exciting current from the motor current detected by the current detecting means, an exciting current command generating means, an output voltage of the inverter circuit, a motor constant set value, an exciting current command, Voltage command generating means for determining using the exciting current, and voltage command correcting means for creating a voltage correction amount so that the exciting current command and the exciting current coincide with each other. Wherein the step-out of the synchronous motor is detected by comparing A washing tub and spin-drying tub, a stirring blade disposed at the bottom of the washing tub and spin-drying tub, an outer tub containing the washing tub and spin-drying tub, and a synchronous motor for rotating the stirring blade or the washing tub and spin-drying tub. In the equipped washing machine,
An inverter circuit for converting the DC voltage into a three-phase AC voltage to drive the synchronous motor, a current detecting means for detecting a current flowing through the synchronous motor, and a control circuit for performing control processing according to a command speed And a driver for driving the inverter circuit,
The control circuit is a coordinate conversion means for calculating an exciting current from the motor current detected by the current detecting means, an exciting current command generating means, an output voltage of the inverter circuit, a motor constant set value, an exciting current command, Voltage command generating means for determining using the exciting current, and voltage command correcting means for creating a voltage correction amount so that the exciting current command and the exciting current coincide with each other. Wherein the step-out of the synchronous motor is detected by comparing In a vacuum cleaner having a main body having a blower for sucking dust, a suction port for sucking dust, and a hose or a pipe portion communicating the suction port with the main body,
A control device for the synchronous motor that drives the blower, an inverter circuit that converts the DC voltage into a three-phase AC voltage to drive the synchronous motor, current detection means that detects a current flowing through the synchronous motor, and control processing according to the command speed. And a driver for driving the inverter circuit,
The control circuit is a coordinate conversion means for calculating an exciting current from the motor current detected by the current detecting means, an exciting current command generating means, an output voltage of the inverter circuit, a motor constant set value, an exciting current command, Voltage command generating means for determining using the exciting current, and voltage command correcting means for creating a voltage correction amount so that the exciting current command and the exciting current coincide with each other. Wherein the step-out of the synchronous motor is detected by comparing

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