JP2003319698A - Sensorless vector control inverter and rotating driver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the quick sensorless detection of locking of a stator of a motor or the abnormal drop of the number of revolutions. <P>SOLUTION: An estimated value of angular frequency of the stator is attained by controlling the armature current of a permanent magnet motor independently while separating the current into a d-axis current and a q-axis current and converging the estimated value of a d-axis induced voltage at the same time. A decision is made that the number of revolutions is abnormal when the difference between the estimated value of angular frequency and the command value of angular frequency exceeds a specified level. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensorless vector control inverter device for a permanent magnet motor in which a permanent magnet is provided in a rotor and an armature winding is provided in a stator, and in particular, the motor is locked or rotated by an external force or the like. The present invention relates to a technique for promptly detecting an abnormal decrease in speed.

[0002]

2. Description of the Related Art In recent years, for motors for compressors and fans for air conditioners, motors for fans, and drive motors for electric vehicles, there has been an increasing demand for variable speed control over a wide range, reduction of power consumption, and improvement of maintainability. Is coming. In order to respond to this, a permanent magnet motor using permanent magnets in the rotor, without installing a sensor for rotor position detection,
Vector control methods using an inverter device have been widely adopted.

However, for example, in a fan motor used in an outdoor unit of an air conditioner, etc., the motor is completely locked due to an external force or a failure of the motor to stop rotating, or the rotation speed is abnormally reduced. May occur. In such a case, if a sensor such as a Hall IC that can detect the motor rotor position is attached to the motor (see, for example, Japanese Patent Application Laid-Open No. 9-74790), rotation is detected by detecting the presence or absence of a signal from the sensor. It is possible to confirm that an abnormality has occurred.

[0004]

However, in the case of sensorless vector control (see, for example, Japanese Patent Application Laid-Open No. 2-124199), since a sensor for detecting the rotor position is not provided, abnormal rotation of the motor is detected. Difficult to detect. Therefore, conventionally, it has been difficult to apply the sensorless vector control to a product that may be locked by an external force or the like, such as a fan.

The present invention has been made in order to eliminate such inconvenience, and when a permanent magnet motor driven by sensorless vector control has a rotation abnormality such as a lock due to an external force or a decrease in rotation speed, An object of the present invention is to provide an inverter device for sensorless vector control that can detect this rapidly and a rotation drive device including the inverter device.

[0006]

In order to achieve the above object, the present invention according to claim 1 is characterized in that the electric current of a permanent magnet motor in which a rotor is provided with a permanent magnet is d parallel to the magnetic flux generated by the permanent magnet. A sensorless vector control inverter device for detecting the angular frequency of the rotor by separating the axial current and the q-axis current orthogonal thereto and controlling each independently and at the same time converging the estimated d-axis induced voltage value to zero. In addition, when the difference between the detected angular frequency and the angular frequency command value exceeds a predetermined value, it is determined that the rotation is abnormal. According to this, the motor angular frequency can be detected without a sensor, and when the motor has an abnormal rotation, the difference between the detected angular frequency and the angular frequency command value becomes large, so that the abnormal rotation can be promptly detected. .

According to a second aspect of the present invention, in the first aspect of the present invention, the q-axis induced voltage calculated from the angular frequency command value is used to determine the abnormal rotation, and the q-axis voltage equation is used to calculate the q-axis induced voltage.
This is performed when the difference from the shaft induced voltage exceeds a predetermined value. Also in this case, the abnormal rotation of the motor reduces the q-axis induced voltage calculated from the q-axis voltage equation and increases the difference from the q-axis induced voltage calculated from the frequency command value. can do.

According to the invention of claim 3, claim 1 or 2
In the invention described in (3), the current to the permanent magnet motor is stopped when the rotation abnormality is determined. When the rotation abnormality occurs, the supply of the overcurrent to the motor is promptly stopped, so that there is an effect that the burnout of the motor and the damage of the switching element in the inverter device can be prevented.

The invention according to claim 4 is the invention according to claims 1 to 3.
In any one of the inventions, the d-axis induced voltage estimated value is a d-axis current and a q-axis current calculated based on a measured current value of the permanent magnet motor, a d-axis voltage command value, and the angular frequency. It is characterized by being obtained from an estimated value and a motor circuit constant. By converging the estimated value of the d-axis induced voltage calculated from such a value to zero, the rotor angular frequency required for the rotation abnormality determination can be detected without using a sensor that detects the rotor angle.

The invention as defined in claim 5 is defined by claim 1 through claim 4.
In any one of the inventions described above, in order to converge the d-axis induced voltage estimated value to zero, an output obtained by calculating the d-axis induced voltage estimated value by a proportional-plus-integral calculator is further calculated by another proportional-integral calculator. It is characterized in that it includes means for giving the calculated output as a q-axis current command value. By using such means, the estimated value of the d-axis induced voltage can be converged to zero, and the rotor angular frequency necessary for the rotation abnormality determination can be detected without using the sensor for detecting the rotor angle. it can.

The invention according to claim 6 is defined by claims 1 to 5.
In any one of the inventions described above, the permanent magnet motor is a fan driving motor.
The fan drive motor is a motor that is prone to abnormal rotation, and each inverter device according to any one of claims 1 to 5,
Since abnormal rotation can be detected quickly without a sensor, it can be applied with confidence.

According to a seventh aspect of the present invention, there is provided a rotary drive device comprising the permanent magnet motor and an inverter device for driving the motor, wherein the inverter device is the rotary drive device.
The inverter device according to any one of 1 to 5 is used. Since each of the inverter devices according to claims 1 to 5 can quickly detect a rotation abnormality without a sensor,
A rotary drive device provided with this has an effect that it can be applied with confidence even to drive a load that is likely to cause abnormal rotation.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below based on examples with reference to the drawings. FIG. 1 is a functional block diagram showing the configuration of a sensorless vector control device for a three-phase permanent magnet motor (hereinafter, simply referred to as a motor) using an inverter device for sensorless vector control (hereinafter, referred to as the present inverter device) of the present invention. Is.

The motor 1 as a load is a rotating field type three-phase permanent magnet motor in which a permanent magnet is provided in a rotor and an armature winding is provided in a stator. Although a sensor for detecting the rotor position is not attached, a current corresponding to the rotor position is supplied from the inverter device to the armature winding, and is thereby driven to rotate.

The inverter device is composed of three means, a current control means 2, a rotor speed / angle estimation means 3 and a rotation abnormality detection means 4. The current control unit 2 is a unit that controls the phase and magnitude of the current flowing through the armature according to the rotor position. The rotor speed / angle estimation means 3 is a means for estimating the angular frequency (rotation speed) of the rotor and the rotor angle, and has a rotational coordinate system (hereinafter referred to as dq coordinate system) defined on the rotor. It is means for estimating an angular frequency and a phase angle with respect to a fixed coordinate system (hereinafter referred to as αβ coordinate system). The rotation abnormality detecting means 4 is means for detecting that the rotor is locked or the rotation speed is abnormally reduced.

Hereinafter, the operation of the entire vector control device will be clarified while explaining the configuration and operation of each means. The three-phase current flowing through the armature winding of the motor 1 is detected by the current detector 5 using a shunt resistor or the like. The detected three-phase currents Ia, Ib, and Ic are calculated by the abc / αβ converter 6 and equivalent two-phase currents Iα and Iα expressed in the αβ coordinate system.
converted to β. The converted two-phase currents Iα and Iβ are subsequently converted into currents Id and Iq expressed in the dq coordinate system by the operation of the αβ / dq converter 7. In the calculation of this coordinate conversion, a rotor angle estimated value (estimated value of the phase angle between the d axis and the α axis) θest estimated by the rotor speed / angle estimation means 3 described later is used.

Here, the dq coordinate system is a coordinate system in which the direction of the magnetic flux produced by the permanent magnets on the rotor is the d axis, and the direction advanced by π / 2 in the rotational direction is the q axis. Current I
d and Iq mean current components in the d-axis direction and the q-axis direction, respectively.

The currents Id and Iq calculated by such coordinate conversion are subtracted from the respective current command values Id-com and Iq-com in the subtracters 8 and 9 to obtain the current deviation ΔId,
ΔIq is calculated. Obtained current deviation ΔId, ΔIq
Is calculated by the corresponding proportional-plus-integral calculators 10 and 11 to generate the d-axis command voltage Vd and the q-axis command voltage Vq at the outputs, respectively. The output command voltages Vd and Vq are armature voltages expressed in the dq coordinate system that should be applied to bring the armature current closer to the current command values Id-com and Iq-com.

The command voltages Vd and Vq are converted by the dq / αβ converter 12 into command voltages Vα and Vβ on the αβ coordinate system. The rotor angle estimated value θest described later is also used in the calculation of the coordinate conversion. PWM former 13
Is the PWM inverter 1 based on the command voltages Vα and Vβ.
A signal for driving the switching element in 4 is generated.
The PWM inverter 14 performs a switching operation according to the signal, whereby a voltage proportional to the voltages Vd and Vq is applied to the armature winding of the motor 1, and the motor 1 is rotationally driven. In this way, the armature current I of the motor 1
The d and Iq are controlled by the adjusting operations of the proportional-plus-integral calculators 10 and 11 so as to match the current command values Id-com and Iq-com.

Here, the current Id-com is a command value of a component (exciting current component) that creates a magnetic flux, and this value is given from the outside. On the other hand, the current Iq-com is the command value of the component (torque current component) that generates the rotational torque, and the motor 1
It is a quantity that is directly related to the rotation speed of. This current command value Iq-com is given as the output of the proportional-plus-integral calculator 15.

The proportional-plus-integral calculator 15 functions together with the subtractor 16 to adjust the rotation speed of the motor 1. The + input terminal of the subtracter 16 has a rotor angular frequency command value ωcom, and the − input terminal has a rotor speed / angle estimation means 3 which estimates the angular frequency estimation value ωest of the motor 1.
Is entered. Then, the deviation is proportional to the proportional-plus-integral calculator 15.
The q-axis current command value Iq-com is generated in the output.

As described above, in order that the exciting current command value Id-com and the torque current command value Iq-com are given independently and the current according to the command value flows in the motor 1, the αβ / dq converter 7 and the It is necessary for the dq / αβ converter 12 to accurately perform coordinate conversion calculation. For that purpose, it is necessary to accurately grasp the rotor angle θ required for the calculation. In the present inverter device, the value of the rotor angle θ is not detected by using a sensor, but is calculated by the rotor speed / angle estimating means 3 using the electric motor model in the dq coordinate system. .

The d-axis induced voltage estimating means 17 calculates the d-axis component estimated value Ed of the induced voltage generated in the armature winding by the rotation of the magnetic flux generated by the permanent magnet attached to the rotor according to the following equation. . Ed = Vd− (R + P · Ld) · Id + ωest · Lq · Iq (1) where R is the winding resistance of the motor 1, Ld and Lq are d axes, and q
Axial inductance, ωest is the estimated angular frequency of the rotor,
P is a differential operator. For the currents Id and Iq, the values obtained by coordinate conversion of the measured current values are used, and for the voltage Vd, the command value is used instead of the measured values because the PWM inverter 14 has good responsiveness.

The angular frequency estimated value ωest is the angular frequency error estimated value ωerror obtained by calculating the d-axis component Ed of the induced voltage obtained by the equation (1) by the proportional-plus-integral calculator 18, and this value is sent to the subtracter 19. The angular frequency command value ωcom is subtracted from the angular frequency command value ωcom to obtain the following formula. ωest = ωcom−ωerror Equation (2) The rotor angle estimated value θest is obtained by integrating the angular frequency estimated value ωest by the integrator 20.

The induced voltage has a q-axis component Eq in addition to the d-axis component Ed calculated by the equation (1). In addition, the angular frequency error estimated value ω error is obtained by calculating the d-axis induced voltage Ed by the proportional-plus-integral calculator 1.
It is a value calculated only by 8. Therefore, the estimated angular frequency error ω error does not represent an accurate angular frequency error. However, the angular frequency estimated value ωest calculated by the equation (2) and the rotor angle estimated value θest obtained by integrating the same are used for coordinate conversion and induced voltage estimation calculation, and further with the help of the controller, the d-axis Considering the case where the induced voltage estimated value Ed can be converged to zero, the estimated value of the induced voltage is only the q-axis component at that time. In this state, the magnetic flux generated by the permanent magnet of the rotor can be estimated to be parallel to the d-axis, and the estimated rotor angle θest at this time is the same as the actual rotor angle θ. Can be estimated.

In the present inverter device, the proportional-plus-integral calculator 1
8 is an angular frequency estimated value ωest, a rotor angle estimated value θest, and a q-axis current command so that the induced voltage Ed is converged to its target zero value with the help of the proportional-plus-integral calculator 15 and the integrator 20. Adjust the value (torque current command value) Iq-com. On the other hand, with respect to the angular frequency of the rotor, the proportional-plus-integral calculator 15 performs an adjusting operation to converge the estimated angular-frequency error value ωerror to zero (the input signal of the proportional-plus-integral calculator 15 is ωerror). As a result of these adjustment operations, both the d-axis induced voltage estimated value Ed and the angular frequency error estimated value ω error converge to zero. Thus Ed
When both ωest and ωest converge to zero, the estimated angular frequency value ωest matches the angular frequency command value ωcom, and the motor 1 is rotationally driven at the angular frequency command value ωcom. That is, the angular frequency estimated value ωest at this time is estimated to be equal to the angular frequency ω of the motor 1, and the angular frequency ω of the motor 1 is detected without using a sensor.

In this way, the control is independently adjusted so that the rotor angular frequency ω matches the external angular frequency command value ωcom and the exciting current Id also matches the external exciting current command value Id-com. Is generally called vector control, and in the case of the present inverter device, a sensor is not used to detect the rotation angle of the rotor, and thus is particularly called sensorless vector control.

In the present inverter device, using the angular frequency estimated value ωest obtained as described above, the rotation abnormality detecting means 4 determines the rotation abnormality as follows. The first mode of determination is that the angular frequency command value ωcom and the angular frequency estimated value ωest
When the difference between and exceeds a predetermined value, that is, when the following equation is satisfied, it is determined that the rotation abnormality has occurred.

| Ωcom−ωest |> X (3) Expression X is a predetermined constant determined by the specifications of the PWM inverter 14 and the motor 1. When the motor 1 is locked by an external force or the like, or the rotation speed deviates from the command value and decreases, the estimated angular frequency value ωest decreases and the equation (3) is satisfied. Abnormal rotation can be detected. According to this criterion, there is an effect that the rotation abnormality can be detected promptly without attaching a sensor for detecting the rotor angle to the motor 1.

The second determination mode is a mode in which it is determined by the magnitude of the q-axis component of the induced voltage. The estimated value Eest1 of the q-axis component of the induced voltage is calculated as follows from the voltage equation for the q-axis. Eest1 = Vq− (R + P · Lq) · Iq−ωest · Ld · Id (4) Equation (4) where the voltage Vq is a q-axis voltage command value.

On the other hand, the induced voltage Eest2 when the motor rotates in conformity with the angular frequency command value ωcom can be expressed by the following equation when the induced voltage constant of the motor 1 is Ke. Eest2 = Ke · ωcom Equation (5) When the motor 1 locks or the rotational speed decreases, the d-axis induced voltage estimated value Eest1 calculated by Equation (4) decreases.
Therefore, it can be determined that the rotation abnormality has occurred when the following expression is established. | Eest2-Eest1 |> Y (6) Expression Y is a predetermined constant determined by the specifications of the PWM inverter 14 and the motor 1. Since the responsiveness of the control system is good, even in the case of this criterion, there is an effect that abnormal rotation can be detected promptly without attaching a sensor for detecting the rotor angle to the motor 1.

When it is determined that the rotation is abnormal according to the reference of the formula (3) or the formula (6), the switching operation of the PWM inverter 14 is stopped and the current supply to the motor 1 is stopped. This prevents the armature winding from being burnt out and the switching element of the PWM inverter 14 from being destroyed.

When the motor 1 is a fan driving motor for driving a fan, the motor may be locked or the rotation speed may be abnormally reduced due to external force or back wind. However, the above-described rotation abnormality detection means is provided. If this inverter device is used, sensorless vector control can be applied without anxiety.

When the permanent magnet motor is inverter-controlled, it is necessary to grasp various motor constants of the permanent magnet motor in order to optimize the control and reflect them in the inverter control. For this reason, today, a permanent magnet motor and an inverter device for driving the same are integrated and often sold as a rotary drive device. In this case, if the present inverter device is adopted as the inverter device, it can be applied with peace of mind even to a load that is apt to cause a lock or an abnormal reduction in rotation speed.

[0035]

As can be understood from the above description, according to the sensorless vector control inverter device of the present invention, it is possible to detect the rotor angle by detecting the rotation abnormality such as the lock of the motor or the abnormal reduction of the rotation speed. It is possible to detect quickly without attaching a sensor. Further, by stopping the current supply to the motor when the rotation abnormality is detected, there is an effect that it can be applied with confidence even to the load drive in which the rotation abnormality is likely to occur.

[Brief description of drawings]

FIG. 1 is a diagram showing functional blocks of an electrical configuration of a vector control inverter device according to an embodiment of the present invention.

[Explanation of symbols]

In the figure, 1 is a permanent magnet motor, 2 is current control means, 3 is rotor speed / angle estimation means, 4 is rotation speed abnormality detection means,
10, 11, 15, and 18 are proportional-plus-integral calculators, 17 is d-axis induced voltage estimation means, ωest is an angular frequency estimated value, Ed is a d-axis induced voltage estimated value, Id is a d-axis current, and Iq is a q-axis current. Show.

Continued front page    F term (reference) 5H560 AA01 BB04 BB12 DA14 DA19                       DB14 DC01 DC12 EB01 JJ02                       JJ05 XA04 XA12 XA15                 5H576 AA08 BB06 BB09 DD02 DD07                       EE01 EE11 EE19 GG02 HB01                       LL14 LL22 LL34 LL35 LL39                       MM05

Claims (7)

[Claims] 1. A current of a permanent magnet motor having a rotor provided with a permanent magnet is separated into a d-axis current parallel to a magnetic flux generated by the permanent magnet and a q-axis current orthogonal thereto, and each is independently controlled. At the same time, the sensorless vector control inverter device detects the angular frequency of the rotor by converging the estimated d-axis induced voltage value to zero, and the difference between the detected angular frequency and the angular frequency command value is a predetermined value. An inverter device for sensorless vector control, characterized in that when it exceeds, it is determined that the rotation is abnormal. 2. When the difference between the q-axis induced voltage calculated from the angular frequency command value and the q-axis induced voltage calculated from the q-axis voltage equation exceeds a predetermined value instead of the determination, abnormal rotation occurs. The sensorless vector control inverter device according to claim 1, wherein 3. When the rotation abnormality is determined,
The sensorless vector control inverter device according to claim 1 or 2, wherein the current to the permanent magnet motor is stopped. 4. The estimated value of the d-axis induced voltage is the d-axis current and the q-axis current calculated based on the measured current value of the permanent magnet motor, the d-axis voltage command value, the angular frequency estimated value, and the motor. The sensorless vector control inverter device according to any one of claims 1 to 3, wherein the inverter device is obtained from a circuit constant. 5. The d-axis induced voltage estimated value is converged to zero by inputting the output obtained by calculating the d-axis induced voltage estimated value by a proportional-plus-integral calculator to another proportional-plus-integral calculator. 5. The sensorless vector control inverter device according to claim 1, further comprising means for giving an output as a q-axis current command value. 6. The sensorless vector control inverter device according to claim 1, wherein the permanent magnet motor is a fan driving motor. 7. A rotation drive device comprising the permanent magnet motor and an inverter device for driving the motor, wherein the inverter device is the inverter device for sensorless vector control according to any one of claims 1 to 5. A rotary drive device characterized by the following.