JP4859576B2 - Method and apparatus for calculating phase error of synchronous motor - Google Patents

Description

  The present invention relates to a phase estimation of a rotor of a synchronous motor, and particularly proposes a method for determining a rotation angular frequency to be switched when the phase error calculation means is switched according to the rotation angular frequency of the rotor of the synchronous motor.

FIG. 2 shows a phase estimation apparatus for a permanent magnet synchronous motor as an example, and the prior art will be described based on this figure.
The estimated phase θ of the permanent magnet of the rotor of the permanent magnet synchronous motor 2 is the γ axis, and the axis orthogonal to the γ axis is the δ axis.
The power converter 1 supplies power to the permanent magnet synchronous motor 2. The current detector 3 detects a primary current i flowing through the permanent magnet synchronous motor 2. The voltage detector 4 detects the primary voltage v applied to the permanent magnet synchronous motor 2. The current component converter 6 performs rotational coordinate conversion on the primary current i based on the estimated phase θ, and outputs the γ-axis component current iγ and the δ-axis component current iδ. The voltage component converter 7 performs rotational coordinate conversion on the primary voltage v based on the estimated phase θ, and outputs it by dividing it into a γ-axis component voltage vγ and a δ-axis component voltage vδ. The current controller 5 outputs a control signal to the power converter 1 such that the γ-axis component current iγ and the δ-axis component current iδ follow a predetermined γ-axis component current command and a δ-axis component current command, respectively. .

  The first phase error calculator 8 inputs iγ, iδ, vγ, vδ and the estimated rotational angular frequency ω of the rotor of the permanent magnet synchronous motor 2,

Thus, a phase error ΔθL obtained by subtracting the phase θ of the γ axis from the phase θR of the d axis, which is the phase of the permanent magnet of the rotor of the permanent magnet synchronous motor 2, is calculated and output. Here, R is the armature winding resistance of the permanent magnet synchronous motor 2, Ld is the d axis inductance of the permanent magnet synchronous motor 2, Lq is the q axis inductance of the permanent magnet synchronous motor 2, and φ is the rotation of the permanent magnet synchronous motor 2. This is the magnetic flux of the permanent magnet of the child, and p () means time differentiation within () .

  The second phase error calculator 9 inputs iγ, iδ, vγ, vδ and the estimated rotational angular frequency ω of the rotor of the permanent magnet synchronous motor 2,

Thus, the phase error ΔθH obtained by subtracting the phase θ of the γ axis from the phase θR of the d axis, which is the phase of the permanent magnet of the rotor of the permanent magnet synchronous motor 2, is calculated and output.

  The switch 12 selects ΔθH if the estimated rotational angular frequency ω of the rotor of the permanent magnet synchronous motor 2 is greater than a predetermined value ωch, and selects and outputs ΔθL if it is smaller. ΔθL is obtained from equation (1), but the denominator may be zero. Therefore, a signal that causes a high-frequency current to flow through the permanent magnet synchronous motor 2 is output from the high-frequency generator 13, and, similar to the switch 12, when the estimated rotational angular frequency ω is smaller than the predetermined value ωch, high-frequency generation occurs. A switch 14 is provided for selecting the output of the device 13 and selecting 0 if it is larger and outputting it. Further, when the permanent magnet synchronous motor 2 is operated at high speed, it becomes impossible to flow a high-frequency current due to voltage saturation of the power converter 1, so that the first phase error calculator 8 and the second phase error calculator 9 Is provided.

The speed calculator 10 receives the primary current i, the primary voltage v, the estimated phase θ, and the output of the switch 12, and estimates and outputs the rotational angular frequency ω of the rotor of the permanent magnet synchronous motor 2. The position estimator 11 receives the estimated rotational angular frequency ω, estimates and outputs the phase θ of the permanent magnet of the rotor of the permanent magnet synchronous motor 2. (For example, Patent Document 1)

Japanese Patent No. 3509016

  If the power converter 1 does not become voltage saturated, the second phase error calculator 9 is not necessary. However, if the first phase error calculator 8 is used, a problem of loss and sound generation occurs because a high-frequency current flows. Therefore, it is preferable to switch to the second phase error calculator 9 as low as possible. However, since ΔθH calculated by the second phase error calculator 9 uses the rotational angular frequency ω estimated in the denominator of equation (2), if ω is low, ΔθH cannot be calculated. Therefore, the rotational angular frequency ωch for switching between the first phase error calculator 8 and the second phase error calculator 9 is determined by the rotational angular frequency at which ΔθH can be calculated, but there is no method for determining ωch and adjustment is required. Become.

  In order to solve the above problems, the present invention provides a phase estimation apparatus for a synchronous motor having a method for determining a rotational angular frequency ωch for switching between a first phase error calculator 8 and a second phase error calculator 9. There is.

In order to solve the above-described problems, at least two kinds of means for calculating the phase error between the actual phase of the rotor of the synchronous motor and the estimated phase of the rotor are prepared , and the phase error is calculated. In the method for calculating the phase error of the synchronous motor configured to switch the means at the rotational angular frequency of the rotor of the synchronous motor, the rotational angular frequency to be switched is determined by the resistance of the armature winding of the synchronous motor and the rated current of the synchronous motor. the synchronous motor is proportional to the rated frequency of, characterized that you calculated is inversely proportional to the rated voltage of the synchronous motor with.
Further, at least two kinds of means for calculating the phase error between the actual phase of the rotor of the synchronous motor and the estimated phase of the rotor are provided, and the means for calculating the phase error is provided as the rotor of the synchronous motor. In the phase error calculation apparatus for a synchronous motor configured to be switched at a rotational angular frequency of And calculating means for calculating in inverse proportion to the rated voltage of the synchronous motor.

  According to the present invention, the rotational angular frequency of the rotor of the permanent magnet synchronous motor and the phase of the permanent magnet of the rotor can be estimated in a wide speed range without adjustment.

  It was possible to determine the rotational angular frequency that can be used for phase error calculation without adjustment.

FIG. 1 is a block diagram of one embodiment of the present invention.
What is different from the prior art of FIG. 2 is a switch 12 'and a switch 14'. The switch 12 ′ selects ΔθH if the estimated rotational angular frequency ω of the rotor of the permanent magnet synchronous motor 2 is larger than the predetermined value ωch, and selects and outputs ΔθL when it is smaller, and the switch 14 ′ is estimated. When the rotation angular frequency ω is smaller than the predetermined value ωch, the output of the high-frequency generator 13 is selected, and if it is larger, 0 is selected and output, but the rotation angular frequency ωch of the predetermined value is

And Here, Ir is a rated current of the permanent magnet synchronous motor 2, Fr is a rated frequency of the permanent magnet synchronous motor 2, Vr is a rated voltage of the synchronous motor, and K is a proportional gain.

The rotation angular frequency ωch to be switched will be described below.
The second phase error calculator 9 calculates ΔθH by equation (2). In equation (2), motor constants of various permanent magnet synchronous motors are used. Among them, the resistance R of the armature winding of the permanent magnet synchronous motor varies greatly with temperature. Therefore, especially when the rotational angular frequency is low, if the accuracy of R is poor, the calculation of ΔθH is affected, and the estimation accuracy of the rotational angular frequency ω and phase θ of the permanent magnet synchronous motor is degraded.
R is used for the numerator of formula (2), and the numerator of formula (2) is a voltage. Therefore, by introducing the ratio of the voltage drop of R with respect to the rated voltage as an evaluation value, the rotational angular frequency ωch that is as low as possible and the switching rotational angular frequency ωch that does not affect the calculation of ΔθH is expressed by the equation (3). It can be obtained.

In the description, a permanent magnet synchronous motor is used, but a similar effect can be obtained with a synchronous motor.

  According to the present invention, since the rotational angular frequency and phase of the rotor of the synchronous motor can be estimated without adjustment, there is great industrial applicability.

It is explanatory drawing which showed Example 1 of this invention. It is explanatory drawing which showed an example of the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power converter 2 Permanent magnet synchronous motor 3 Current detector 4 Voltage detector 5 Current controller 6 Current component converter 7 Voltage component converter 8 1st phase error calculator 9 2nd phase error calculator 10 Speed estimator 11 Position estimator 12, 12 'switch 13 High frequency generator 14, 14' switch

Claims (2)

At least two types of means for calculating the phase error between the actual phase of the rotor of the synchronous motor and the estimated phase of the rotor are prepared , and the means for calculating the phase error is the rotation of the rotor of the synchronous motor. In the phase error calculation method of the synchronous motor configured to switch at the angular frequency,
In proportion to the rotational angular frequency in which the switching to the rated frequency of the synchronous motor to the rated current of the synchronous motor and the resistance of the armature winding of the synchronous motor, characterized that you calculated it is inversely proportional to the rated voltage of the synchronous motor A phase error calculation method for a synchronous motor. At least two types of means for calculating the phase error between the actual phase of the rotor of the synchronous motor and the estimated phase of the rotor are provided, and the means for calculating the phase error is the rotation of the rotor of the synchronous motor. In the phase error calculation device of the synchronous motor configured to switch at the angular frequency,
Computation means for making the rotation angular frequency to be switched proportional to the resistance of the armature winding of the synchronous motor, the rated current of the synchronous motor, and the rated frequency of the synchronous motor, and inversely proportional to the rated voltage of the synchronous motor. A phase error calculation device for a synchronous motor characterized by the above.

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