JP2008312384A - Motor control unit and control method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor control unit and its control method, which can estimate the rotational position angle of a motor, with respect to set errors of the accuracy of voltage and current, and the electrical constants of the motor. <P>SOLUTION: The motor control unit is provided with a voltage superimposing machine (25) which superimposes an AC voltage command on a voltage command to the motor (24); a current coordinate converter (26), which coordinate-converts motor current into a phase command, an in-phase component (γ-axis current) and an in-phase component (δ-axis current) advanced by 90 degrees; a current extraction unit (27) for extracting the current of the frequency a component which is the same as that of the AC voltage command from δ-axis current; and a phase correction machine (28) that calculates the phase correction amount, by using the current extracted and correcting it to the phase command. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric motor control device that performs speed control without a speed sensor and a control method thereof.

A conventional motor control device that performs speed control without a speed sensor superimposes an AC voltage signal, and estimates it from the estimated position using the superimposed AC voltage signal and the output current that flows at that time, and the voltage-current equation of the motor. Two estimated values of the position estimated value are switched according to the driving situation (see Patent Document 1).
FIG. 3 is a schematic block diagram of a conventional motor control device, in which 5 is an inverter, and voltage command values v ^* _{1, α} , v ^* _{1, β} are _added to high-frequency voltage command values v ^* _{h, α} , v ^* _h, A voltage with _β superimposed is input. Reference numeral 6 denotes a 3/2 phase conversion unit, which converts the voltages vu, vv, vw and currents iu, iv, iw detected from the inverter 5 to obtain voltages v _α , v _β and currents i _α , i _β . . Reference numeral 11 denotes a λ _d calculation unit, which is based on the voltages v _α and v _β , the currents i _α and i _β , and the q-axis inductance L _q of the salient pole motor 2, and the flux linkage number λ _{d, α} , λ _{d, β} Ask for. Reference numeral 12 denotes a BPF unit which filters the number of magnetic flux linkages in the vicinity of the angular frequency ω _h to obtain high frequency components λ _{d, h, α} , λ _{d, h, β} . _{Reference numeral} 15 denotes an identification signal generator, which obtains a high frequency component i _dh of the d-axis current. Reference numeral 13 denotes a position angle calculation unit which obtains the rotational position angle θ _re of the salient pole motor 2 from the high frequency components λ _{d, h, α} , λ _{d, h, β} , i _dh .
As described above, the conventional motor control device superimposes the high frequency voltage on the inverter, obtains the number of magnetic flux linkages from the voltage and current at that time, and the inductance of the salient pole motor. The first high-frequency component is obtained by filtering near the angular frequency, a second high-frequency component having an angular frequency near the angular frequency is obtained, and the salient pole motor is determined from the first high-frequency component and the second high-frequency component. The rotational position angle is estimated.
Japanese Patent Laying-Open No. 2005-160287 (FIG. 1)

The conventional motor control device superimposes the high-frequency voltage, and uses the set values of the voltage, current and salient pole motor inductance at that time to determine the number of magnetic flux linkages to estimate the rotational position angle. Since the motor electric constants to be set are required to be accurate and accurate values, there has been a problem that normal driving cannot be performed depending on the degree of error of these values.
The present invention has been made in view of such problems, and an electric motor control apparatus capable of robustly estimating the rotational position angle of an electric motor with respect to setting errors of voltage and current accuracy and electric constants of the electric motor. And it aims at providing the control method.

In order to solve the above problem, the present invention is configured as follows.
The invention according to claim 1 is a voltage command device that outputs a voltage command corresponding to a speed command to the motor, an integrator that generates a phase command using the speed command, and a motor current that flows through the motor. And a power converter for supplying a voltage based on the voltage command and the phase command to the motor, and a voltage superimposing device that superimposes an AC voltage command on the voltage command to the motor A current coordinate converter that converts the motor current into a phase component (γ-axis current) that is the same phase as the phase command (γ-axis current) and a phase component that is advanced 90 degrees (δ-axis current), and the AC voltage command from the δ-axis current. A current extractor that extracts a current having the same frequency component and a phase corrector that calculates a phase correction amount using the extracted current and corrects the phase command are provided.

According to a second aspect of the present invention, in the first aspect of the present invention, the AC voltage command superimposed by the voltage superimposing device is a high-frequency signal.
According to a third aspect of the present invention, the power converter uses the AC voltage command as a command of the same phase component (γ-axis voltage) as the phase command, and the output of the voltage command device is advanced by 90 degrees. A voltage command supplied to the electric motor is generated as a component (δ-axis voltage) command.

In order to solve the above problem, the present invention is as follows.
According to a fourth aspect of the present invention, a voltage command unit that outputs a voltage command corresponding to a speed command to the motor, an integrator that generates a phase command using the speed command, and a motor current flowing through the motor are detected. And a power converter for supplying a voltage based on the voltage command and the phase command to the electric motor, wherein the motor current is the same phase component current ( γ-axis current) and a phase component current (δ-axis current) advanced by 90 degrees, an AC voltage command is superimposed on the voltage command to the motor, and the δ-axis current has the same frequency component as the AC voltage command. A current is extracted, a phase correction amount is calculated using the extracted current, the phase command is corrected using the phase correction amount, and the voltage command, the AC voltage command, and the corrected phase command are corrected. Based on The procedure of supplying voltage to the motor was taken.

The invention according to claim 5 is the invention according to claim 4, wherein the AC voltage command superimposed on the voltage command to the electric motor is a high-frequency signal.
The invention according to claim 6 is the invention according to claim 4, wherein the AC voltage command is a command of the same phase component (γ-axis voltage) as the phase command, and the output of the voltage command device is 90 degrees. As a command for the advanced phase component (δ-axis voltage), a procedure for generating a voltage command to be supplied to the electric motor was taken.

  According to the invention described in the claims, the rotational position angle of the electric motor can be estimated robustly with respect to the setting error of the accuracy of the voltage and current and the electric constant of the electric motor. The speed control of the motor can be performed robustly.

  Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic block diagram of an electric motor control device of the present invention. In the figure, a voltage command device 21 performs FV conversion and outputs an induced voltage command proportional to a speed command ωref to the motor 24 as a δ-axis voltage command Vδref. The integrator 22 integrates the speed command ωref to generate a phase command θref. The current detector 30 detects motor currents Iu and Iw flowing through the motor 24, and the power converter 23 is a phase command in which a voltage command of Vδref is given as a δ-axis voltage command and a voltage command of Vγref as described later is a γ-axis voltage command. Although it is converted into a three-phase voltage command, and further not shown, three-phase voltages Vu, Vv, and Vw that are pulse width modulated using a carrier wave signal are generated and supplied to the motor 24 that is a load.

  The voltage superimposing unit 25 superimposes the AC voltage command on the γ-axis voltage command and outputs the γ-axis voltage command Vγref. The current coordinate converter 26 inputs the motor currents Iu and Iw detected by the current detector 30 and the phase component current (γ-axis current) and the phase component current advanced by 90 degrees (δ-axis current). ) And output as Iγ and Iδ, respectively. The current extractor 27 extracts a current Iδinj having the same frequency component as the γ-axis voltage command Vγref superimposed on the γ-axis voltage command from the δ-axis current Iδ. The phase corrector 28 calculates the phase correction amount Δθ using the extracted δ-axis current Iδinj. The adder 29 adds the phase command θref generated by the integrator 22 and the phase correction amount Δθ calculated by the phase corrector 28. In this way, the speed control of the electric motor 24 is performed.

  The difference between the present invention and the prior art is that two estimated values, a position estimated value estimated based on the superimposed AC voltage signal and the motor current at that time, and a position estimated value estimated based on the voltage-current equation of the motor are used as driving conditions. And the phase command is obtained as an addition value of the correction value Δθ calculated using the current value of the same frequency component as the AC voltage command superimposed with the integral value θref of the speed command. It is a part that.

In the following, the differences from the prior art will be described focusing on the calculation processing of the phase correction value Δθ.
The current coordinate converter 26 obtains the γ-axis current Iγ and the δ-axis current Iδ by the coordinate conversion shown in the equation (1) using the motor currents Iu and Iw detected by the current detector 30. At this time, Kirchhoff's law is obtained. The detection of one phase of the motor current (Iu, Iv, Iw) may be used as Iv = − (Iu + Iw). It should be noted that θ shown in equation (1) represents a corrected phase command θref ′ output from an adder 19 described later.

Next, the current extractor 27 has the configuration shown in FIG. 2, and the δ-axis current Iδ output from the current coordinate converter 26, the sin ωt signal, and the cos ωt signal (ω: the frequency of the superimposed AC voltage command). The product is multiplied using multipliers 41 and 42, and the multiplication results are input to low-pass filters 43 and 44, respectively, and the amplitude is obtained by the amplitude calculator 45 to obtain the extracted δ-axis current Iδinj. A current having the same frequency component ω as the superimposed γ-axis voltage command Vγref is obtained as the extracted δ-axis current Iδinj.
This process can be expressed as in equation (2), where T is the time constant of the low-pass filters 43 and 44, t is the time, and s is the Laplace transform operator. The time constant T of the low-pass filters 43 and 44 is desirably set to 10 / ω or less with respect to the frequency ω of the superimposed AC voltage command.

  Next, the phase corrector 28 performs PI (proportional / integral) control so that the extracted δ-axis current Iδinj becomes zero, and outputs a phase correction amount Δθ. The magnitude of the extracted δ-axis current Iδinj is based on the finding that it is proportional to the error between the control phase and the motor phase. This process can be expressed as in equation (3).

The adder 29 adds the phase correction amount Δθ obtained by the equation (3) and the phase command θref obtained by integrating the speed command ωref. This added value is input to the power converter 23 and the current coordinate converter 26 as a phase command θref ′.
In order to easily extract only the current component in the vicinity of the frequency ω of the AC voltage command Vγref superimposed by the current extractor 27, it is desirable that the frequency of the speed command has a difference as large as possible. That is, the frequency ω of the voltage command to be superimposed is desirably a high frequency.
In the above description, the output of the voltage command device 21 is the δ-axis voltage command Vδref, and the AC voltage command that is the output of the voltage superimposing device 25 is the γ-axis voltage command Vγref, but the motor electrical constant, motor current, and speed command The present invention is similarly applied to a configuration in which a voltage command for a γ-axis component is created using some and added to an AC voltage command that is an output of the voltage superimposing unit 25 to be a new γ-axis voltage command Vγref. Can be implemented.

In this way, the phase command is the integral value of the speed command value that is not affected by the motor electrical constant, current, and voltage information as the main phase information, and only the phase command and motor position correction amount are extracted by the voltage superposition method. Since the configuration is such that the calculation is performed based on the information, the speed control of the motor can be performed very robustly with respect to the setting error of the accuracy of the voltage and current and the electric constant of the motor.
In addition, in embodiment mentioned above, it can also apply to the reluctance motor which does not have a saliency motor which has a magnet, or a magnet.

1 is a schematic block diagram of an electric motor control device showing a first embodiment of the present invention. Configuration diagram of current extractor 27 of the present invention Schematic block diagram of a conventional motor control device

Explanation of symbols

2 Salient pole motor 5 Inverter 6 3/2 phase conversion unit 11 λ _d calculation unit 12 BPF unit 13 Position angle calculation unit 15 Identification signal generation unit 21 Voltage command unit 22 Integrator 23 Power converter 24 Electric motor 25 Voltage superimposer 26 Current Coordinate converter 27 Current extractor 28 Phase corrector 29 Adder 30 Current detector 41, 42 Multiplier 43, 44 Low-pass filter 45 Amplitude calculator

Claims (6)

A voltage command device that outputs a voltage command corresponding to a speed command to the motor, an integrator that generates a phase command using the speed command, a current detector that detects a motor current flowing through the motor, and a motor In an electric motor control device comprising a power converter that supplies a voltage based on the voltage command and the phase command,
A voltage superimposing device that superimposes an AC voltage command on a voltage command to the electric motor;
A current coordinate converter for converting the motor current into a phase component (γ-axis current) and a phase component advanced by 90 degrees (δ-axis current) as the phase command;
A current extractor that extracts a current having the same frequency component as the AC voltage command from the δ-axis current;
An electric motor control device comprising: a phase corrector that calculates a phase correction amount using the extracted current and corrects it to the phase command.   The electric motor control apparatus according to claim 1, wherein the AC voltage command superimposed by the voltage superimposing device is a high-frequency signal.   The power converter uses the AC voltage command as a command of the same phase component (γ-axis voltage) as the phase command, and a command of a phase component (δ-axis voltage) advanced 90 degrees from the output of the voltage command device. The motor control device according to claim 1, wherein a voltage command to be supplied to the motor is generated. A voltage command device that outputs a voltage command corresponding to a speed command to the motor, an integrator that generates a phase command using the speed command, a current detector that detects a motor current flowing through the motor, and a motor In a control method of an electric motor control device comprising a power converter that supplies a voltage based on the voltage command and the phase command,
Coordinates the motor current into a phase component current (γ-axis current) that is the same as the phase command and a phase component current (δ-axis current) advanced by 90 degrees,
Superimposing an AC voltage command on the voltage command to the motor,
Extract the current of the same frequency component as the AC voltage command from the δ-axis current,
A phase correction amount is calculated using the extracted current,
Correct the phase command using the phase correction amount,
A method for controlling an electric motor control device, comprising: processing according to a procedure for supplying a voltage to the electric motor based on the voltage command, the AC voltage command, and the corrected phase command.   The control method for the motor control device according to claim 4, wherein the AC voltage command superimposed on the voltage command to the motor is a high-frequency signal.   The AC voltage command is a command of the same phase component (γ-axis voltage) as the phase command, and the voltage command supplied to the electric motor is a command of the phase component (δ-axis voltage) advanced by 90 degrees. The method for controlling an electric motor control device according to claim 4, wherein: