JP2011125100A - Controller for permanent-magnet synchronous motors - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine a phase correction value for obtaining a d-axis phase as the permanent magnet position of the rotor of a permanent-magnet synchronous motor, without having to attach an electromagnetic contactor between a power converter and the permanent-magnet synchronous motor. <P>SOLUTION: The power converter supplies power to the permanent-magnet synchronous motor and makes the synchronous motor rotate at a predetermined number of rotations. Thereafter, the motor is kept in rotation, and the current is controlled to a current with a magnitude of zero or near zero; to thereby timewise integrating the terminal-to-terminal voltage of the motor, to determine the magnetic flux of a permanent magnet existing in the rotor of the motor. When the phase of the magnetic flux is determined, since the magnetic flux phase agrees with the d-axis phase as the permanent magnet position of the motor, the phase correction value is obtained by subtracting the magnetic flux phase from the phase output of a phase detector; and the controller of the permanent-magnet synchronous motor is provided with a phase correction value detector that carries out the computation and a phase correction value storage device that stores the phase correction value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a function of automatically measuring a phase correction value used when obtaining a d-axis phase which is a permanent magnet position of a rotor of a permanent magnet synchronous motor from a phase detector output and storing the phase correction value in the apparatus.

  Permanent magnet synchronous motors have been widely used in recent years because they are smaller and more efficient than induction motors in which excitation is obtained from a permanent magnet by attaching a permanent magnet to a rotor and excitation is supplied from a power source. In order to control the permanent magnet synchronous motor, it is necessary to know the d-axis phase that is the permanent magnet position of the rotor. For this purpose, as shown in FIG. 1, there is a method of detecting by attaching a phase detector for detecting the d-axis phase which is the position of the permanent magnet.

  However, since the phase detector may be attached to an arbitrary phase regardless of the d-axis phase that is the permanent magnet position of the rotor of the permanent magnet synchronous motor, the d-axis phase that is the permanent magnet position and the phase detector. An error may occur in the phase output indicated by. Therefore, it is necessary to know the correct phase by subtracting a predetermined value (hereinafter referred to as a phase correction value) from the output of the phase detector. A conventional technique for measuring this phase correction value is disclosed in Japanese Patent Laid-Open No. 9-47066. According to this publication, an electromagnetic contactor is attached between a permanent magnet synchronous motor and a power converter that drives the permanent magnet synchronous motor, and when driving the permanent magnet synchronous motor, the electromagnetic contactor is closed. Drive. When measuring the phase correction value, the power converter supplies power to the permanent magnet synchronous motor with the electromagnetic contactor closed, and rotates the permanent magnet synchronous motor at a predetermined rotational speed. The voltage between terminals of the permanent magnet synchronous motor is measured by opening the magnetic contactor, and the phase of the voltage obtained by converting the voltage between the terminals into a square wave and the absolute value of the rotation angle on the rotating shaft of the permanent magnet synchronous motor A phase detector for output is attached, and a phase difference from the phase output of the phase detector is detected to obtain a phase correction value. Therefore, if the electromagnetic contactor is not attached between the power converter and the permanent magnet synchronous motor, the voltage obtained by converting the terminal voltage of the permanent magnet synchronous motor into a square wave cannot be measured, and the phase correction value Cannot be detected.

JP-A-9-47066

  The problem to be solved is that the phase correction value of the d-axis phase that is the permanent magnet position of the permanent magnet synchronous motor cannot be obtained unless an electromagnetic contactor is attached between the power converter and the permanent magnet synchronous motor. is there.

  According to the first aspect of the present invention, the phase detector for detecting the rotational phase of the rotor of the permanent magnet synchronous motor, and the permanent magnet position of the rotor by subtracting the phase correction value from the output of the phase detector. In a control apparatus for a permanent magnet synchronous motor, comprising: a phase corrector for obtaining a d-axis phase; and a power converter that supplies power to the permanent magnet synchronous motor based on the d-axis phase that is an output of the phase corrector. After supplying electric power to the permanent magnet synchronous motor and rotating the permanent magnet synchronous motor at a predetermined number of revolutions, the input current of the permanent magnet synchronous motor is set to zero or a value close thereto while maintaining the rotated state. The power converter is controlled so that the voltage of the permanent magnet synchronous motor is integrated to obtain a magnetic flux, and since the phase of the magnetic flux coincides with the d-axis phase, the level of the magnetic flux is determined from the output of the phase detector. It is necessary to update the phase correction value by providing a phase correction value detector for obtaining the phase correction value by subtracting and a phase correction value storage for storing the phase correction value obtained by the phase correction value detector. The controller for a permanent magnet synchronous motor is characterized in that the phase correction value detector is operated when there is any.

  In the present invention, without attaching an electromagnetic contactor between a power converter and a permanent magnet synchronous motor, the power converter supplies power to the permanent magnet synchronous motor to rotate the permanent magnet synchronous motor at a predetermined rotational speed. The rotor of the permanent magnet synchronous motor is maintained by maintaining the rotated state, controlling the current to zero or a minute current close thereto, and integrating the voltage between the terminals of the permanent magnet synchronous motor over time. When the magnetic flux of the permanent magnet is obtained and the phase of the magnetic flux is obtained, the magnetic flux phase coincides with the d-axis phase that is the permanent magnet position of the permanent magnet motor, so the magnetic flux phase is calculated from the phase output of the phase detector. The phase correction value is obtained by subtraction.

  In the present invention, a power converter supplies electric power to a permanent magnet synchronous motor and rotates the permanent magnet synchronous motor at a predetermined rotational speed, and then maintains the rotated state so that the current is small or close to zero. The voltage between terminals of the permanent magnet synchronous motor can be detected without attaching an electromagnetic contactor between the power converter and the permanent magnet synchronous motor to control the current to a magnitude, and the voltage between the terminals is integrated over time. Thus, when the magnetic flux of the permanent magnet in the rotor of the permanent magnet synchronous motor is obtained and the phase of the magnetic flux is obtained, the magnetic flux phase matches the d-axis phase which is the permanent magnet position of the permanent magnet motor. The phase correction value is obtained by subtracting the magnetic flux phase from the phase output of the phase detector, and the permanent magnet position of the rotor of the permanent magnet synchronous motor is obtained by subtracting the phase correction value from the phase output of the phase detector. There d axis phase is that it can be detected.

It is explanatory drawing which showed the implementation method by this invention. Example 1 It is explanatory drawing which showed the phase correction value detection procedure of the permanent magnet synchronous motor. FIG. 5 is a diagram showing a time integral of a voltage vector of a permanent magnet synchronous motor using a complex number.

  Embodiments of the present invention will be described below.

FIG. 1 is a diagram showing an embodiment of the present invention. The power converter 1 supplies power to the permanent magnet synchronous motor 2. The d-axis phase detector 3 outputs a d-axis phase θd that is a permanent magnet position of the rotor of the permanent magnet synchronous motor 2. The current detector 4 detects the current output from the power converter 1, and the voltage detector 5 detects the voltage output from the power converter 1. Based on the d-axis phase θd, the current component converter 6 outputs the input current i of the permanent magnet synchronous motor 2 from the current detector 4 to the q-axis component current iq orthogonal to the d-axis component current id. The command converter 7 receives the torque command T ^* and outputs current commands id ^* and iq ^* for each axis such that the output torque of the permanent magnet synchronous motor follows the torque command T ^* . The current controller 8 outputs a voltage command v ^* such that each axis current id, iq of the output of the current component converter 6 follows their command values id ^* , iq ^* . When the output torque of the permanent magnet synchronous motor follows the torque command T ^* , the switch 11 selects the voltage command v ^* of the current controller 8, and the current controller 8 causes the power converter 1 to Controlled to output v ^* power. The d-axis phase detector 3 subtracts the phase correction value θx stored in the phase correction value storage 9 by the phase corrector 32 from the rotor phase θr of the permanent magnet synchronous motor 2 detected by the phase detector 31. The d-axis phase θd is obtained.

For example, when the contents of the phase correction value storage 9 must be updated when the phase detector 31 is replaced, the switch 11 selects the voltage command v1 ^* of the phase correction value detector 10, and the phase correction value detector 10, the power converter 1 is controlled to output power according to the voltage command v 1 ^* . The phase correction value detector 10 uses the current i from the current detector 4 and the voltage v from the voltage detector 5 to control the power converter 1 so that a predetermined current flows through the permanent magnet synchronous motor 2 to correct the phase. The value θx is obtained.

A method for detecting the phase correction value θx will be described below. FIG. 2 shows the inside of the phase correction value detector 10. When the switch 11 selects the output v1 ^* of the phase correction value detector 10, the phase correction value detection current controller 101 rotates the permanent magnet synchronous motor 2 to the rotation angular frequency ω0, and then the rotation angular frequency ω0. The power converter 1 is controlled so that a current of zero or a minute magnitude close to it is allowed to flow while maintaining the rotating state. The voltage integrator 102 calculates the inter-terminal voltage v detected when the phase correction value detection current controller 101 controls the power converter 1 so that the current flows through the power converter 1 with a minute current close to or close to zero. The integrated value S (v) obtained by the integration is output to the phase converter 103. The phase converter 103 converts the integrated value S (v), which is the output of the voltage integrator 102, into a phase, and outputs an integrated phase value θs to the phase correction value calculator 104. The phase correction value calculator 104 calculates the phase correction value θx by subtracting the integral phase value θs from the phase θr that is the output of the phase detector 31, and outputs it to the phase correction value storage 9. The phase correction value storage 9 stores the input phase correction value θx immediately before the switch 11 selects the voltage command v ^* and the current controller 8 controls the power converter 1.

  A method for detecting the phase correction value θx will be described below. Generally, the voltage v of the permanent magnet synchronous motor is expressed as shown in Equation 1.

(Equation 1)
v = R1 · i + L · D (i) + D (φ2) Equation 1

Here, R1 is a primary winding resistance, L is an inductance, v is an input voltage vector, i is an input current vector, φ2 is a secondary magnetic flux vector, and D () represents time differentiation. The phase correction value detection current controller 101 maintains the rotated state after rotating the permanent magnet synchronous motor 2 when the switch 11 selects the output v1 ^* of the phase correction value detector 10 In order to control the power converter 1 so that a current of zero or a very small current flows therethrough, the first term and the second term on the right side of Equation 1 can be ignored, so the input voltage vector v is given by Equation 2. become.

(Equation 2)
v = D (φ2) Equation 2

Here, assuming that the secondary magnetic flux vector φ2 rotates at the rotational angular frequency of ω0, the secondary magnetic flux vector φ2 can be expressed as shown in Equation 3.

(Equation 3)
φ2 = φ0 · EXP {j · (ω0 · t + α)} Equation 3

Here, φ0 represents the magnitude of the secondary magnetic flux vector φ2, EXP () represents an exponential function, t represents time, and j represents an imaginary unit. Α represents an initial value of the rotational phase of the secondary magnetic flux vector rotating at the rotational angular frequency of ω0, and is an arbitrary value. As shown in Equation 3, the vector is expressed using complex numbers. Next, when the secondary magnetic flux vector φ2 of Expression 3 is substituted into Expression 2, Expression 4 is obtained.
(Equation 4)
v = j · ω0 · φ0 · EXP {j · (ω0 · t + α)} Equation 4

  From Equation 4, it can be seen that the phase of the input voltage vector v is 90 degrees ahead of the secondary magnetic flux vector φ2, and is the rotational angular frequency ω0. Next, when Expression 4 is integrated, Expression 5 is obtained.

(Equation 5)
S (v) = φ0 · EXP {j · (ω0 · t + α)} + S0 Equation 5

  Here, S () represents time integration, and S0 represents an integration constant vector in time integration. The integral value S (v) obtained by time-integrating the voltage from Equation 5 is a vector rotating at the center S0 with the magnitude φ0 and the rotation angular frequency ω0. FIG. 3 shows Equation 5 in the coordinates where the vertical axis is the complex imaginary axis, the horizontal axis is the complex real axis, and the point where the intersection of the real axis and the imaginary axis is zero. When the center S0 is placed at an arbitrary point on the coordinates, the integral value S (v) rotates from the center S0 at a rotational angular frequency ω0 while drawing a circular locus as shown by a dotted line with a size φ0. When the real axis is defined as a reference axis, the integral phase value θs of the integral value S (v) is a phase difference from the reference axis. Since the integral value S (v) is obtained by time-integrating the voltage v of the permanent magnet synchronous motor, it coincides with the translation of the secondary magnetic flux vector of the permanent magnet synchronous motor. Therefore, since the integral phase value θs coincides with the d-axis phase θd that is the permanent magnet position of the rotor of the permanent magnet synchronous motor, the phase is obtained by subtracting the integral phase value θs from the phase θr that is the output of the phase detector 31. A correction value θx is obtained.

  In the present invention, after the power converter supplies electric power to the permanent magnet synchronous motor and rotates the permanent magnet synchronous motor, the rotating state is maintained and the current is controlled to zero or a minute current close thereto. Then, the voltage between the terminals of the permanent magnet synchronous motor is detected from the voltage detector, and the magnetic flux of the permanent magnet in the rotor of the permanent magnet synchronous motor is obtained by time integration, and the phase output of the phase detector is calculated from the phase of the magnetic flux. Since the phase correction value is obtained, there is no need to attach an electromagnetic contactor between the power converter and the permanent magnet synchronous motor. Furthermore, the voltage between the terminals of the permanent magnet synchronous motor is detected from the voltage detector, but since the power converter is controlled to output power according to the voltage command by the voltage command, the voltage command and the voltage detector The detected voltages are equal and the voltage detector can be omitted. Therefore, it leads to cost reduction.

DESCRIPTION OF SYMBOLS 1 Power converter 2 Permanent magnet synchronous motor 3 d-axis phase detector 31 Phase detector 32 Phase corrector 4 Current detector 5 Voltage detector 6 Current component converter 7 Command converter 8 Current controller 9 Phase correction value memory | storage device DESCRIPTION OF SYMBOLS 10 Phase correction value detector 101 Phase correction value detection current controller 102 Voltage integrator 103 Phase converter 104 Phase correction value calculator 11 Switch

Claims (1)

A phase detector for detecting the rotational phase of the rotor of the permanent magnet synchronous motor, and a phase corrector for obtaining a d-axis phase which is a permanent magnet position of the rotor by subtracting a phase correction value from the output of the phase detector; In the control device for a permanent magnet synchronous motor that includes a power converter that supplies power to the permanent magnet synchronous motor based on the d-axis phase that is the output of the phase corrector, power is supplied to the permanent magnet synchronous motor. The permanent magnet synchronous motor is rotated at a predetermined rotational speed, and the power converter is controlled so that the input current of the permanent magnet synchronous motor becomes zero or close to the value while maintaining the rotated state. Then, the voltage of the permanent magnet synchronous motor is integrated to obtain a magnetic flux, and since the phase of the magnetic flux matches the d-axis phase, the phase complement is obtained by subtracting the phase of the magnetic flux from the output of the phase detector. A phase correction value detector for obtaining a value and a phase correction value storage for storing the phase correction value obtained by the phase correction value detector are provided, and the phase correction is required when the phase correction value needs to be updated. A control device for a permanent magnet synchronous motor, wherein a value detector is operated.

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