JP4765272B2 - Method for estimating initial magnetic pole position of permanent magnet brushless motor and permanent magnet brushless motor control device - Google Patents

Description

  The present invention relates to detection of an initial magnetic pole position of a permanent magnet type brushless motor, and more particularly to a method of detecting a magnetic pole position of a rotor at the time of activation of the brushless motor and a permanent magnet type brushless motor control apparatus for executing the method.

As a method for detecting the magnetic pole position of the rotor at the time of starting the conventional brushless motor, a method disclosed in Patent Document 1 related to the present applicant is known.
This is because the δ axis is arbitrarily set on the spatial coordinates and the δ axis is set in a direction advanced by 90 ° from the γ axis, and the current control system in the γ axis direction is configured by a closed loop and the current control system in the δ axis direction Is formed as an open loop, and the interference current generated in the δ-axis direction when the current command in the γ-axis direction is given as a stepped alternating current command is observed. From the state equation of the permanent magnet motor at zero speed Of the derived formulas (1) and (2), when the sign of the product (fγ) of the integrated value of the interference current and the γ-axis current command value is positive from the formula (1), the γ-axis is set to a small angle Δθ1. When the sign is negative, the phase is delayed by a small angle Δθ1 so that the γ axis coincides with the true magnetic axis d axis or the −d axis advanced 180 ° from the true magnetic axis.
Japanese Patent No. 3282657

Specifically, in the equations (1) and (2), the current command in the γ-axis direction is iγ _Ref , the interference current in the δ-axis direction is iδ, the q-axis inductance is L _q , the d-axis inductance is L _d , The child winding resistance is R _s , and the electrical angle error between the γ-axis and the d-axis is θe.
fγ = sign (iγ _Ref ) · lim∫0∞iδdt (1)
fγ = sign (iγ _Ref ) · ((L _q −L _d ) / 2R _S ) · sin 2θ _e · iγ _Ref
... (2)

In the initial magnetic pole position estimation method described in Patent Document 1, when the sign of the product (fr) of the integral value of the interference current and the γ-axis current command value is positive from equation (1), the γ-axis is advanced by a small angle Δθ1. When the sign is negative, the phase is delayed by a small angle Δθ ₁ so that the γ axis coincides with the true magnetic axis d axis or −d axis advanced 180 ° from the true magnetic axis. In the range of 0 to 2π, when the electrical angle error θ _e between the γ axis and the d axis is 0 °, π / 2, π, 3π / 2 or 2π, the integral value of the interference current and the γ axis current command value Product (fr) becomes 0.
When the phase of 0 °, π, or 2π is the magnetic pole position estimation start phase θ _S , the true magnetic axis d axis or the −d axis advanced by 180 ° from the true magnetic axis coincides with the estimation process. No problem to complete.
However, when the phase of π / 2 or 3π / 2 is the magnetic pole position estimation start phase θ _S , the establishment time until the γ axis coincides with the true magnetic axis d axis or the −d axis advanced 180 ° from the true magnetic axis. There was a problem that it took a long time.
In addition, when the establishment time is fixed, there is a problem that the magnetic pole position estimation accuracy is deteriorated.
The present invention has been made in view of such problems, and by estimating the magnetic pole position estimation start phase θ _S in advance, regardless of the electrical angle of the reference phase θ ₀ at which the estimation of the initial magnetic pole is started, γ It is an object of the present invention to provide an apparatus and a method that can fix the establishment time until the axis is matched with the true magnetic axis d-axis or the -d-axis advanced 180 ° from the true magnetic axis and improve the magnetic pole position estimation accuracy. .

In order to solve the above problem, the present invention is as follows.
The invention of the method for estimating the initial magnetic pole position of a permanent magnet type brushless motor according to claim 1 is characterized in that a δ axis is arbitrarily set in spatial coordinates and a δ axis is set in a direction advanced from the γ axis by an electrical angle of 90 °. The current control system is configured in a closed loop and the current control system in the δ-axis direction is configured in an open loop, and is generated in the δ-axis direction when the current command in the γ-axis direction is given as a stepped alternating current command. A magnetic pole position estimation method for a permanent magnet type brushless motor that observes an interference current and estimates a magnetic pole position based on a sign of a product of an integral value of the interference current and a γ-axis current command value,
First, the interference current is observed for each phase shifted by Δθ in the range of the rotor electrical angle of 0 to 2π from an arbitrary reference phase θ0, and from the observed interference current, the equations (3) and (4) ) To calculate and store the interference current amount fγs by
Of the phases shifted by Δθ, the phase at which the stored interference current amount fγs is maximum is defined as a magnetic pole position estimation start phase θS .
Thereafter, the magnetic pole position is estimated from the magnetic pole position estimation start phase θS.
fγs = | lim∫0∞iδdt | (3)
fγs = | ((Lq−Ld) / 2RS) · sin 2θe · iγRef | (4)
Where i δ is the interference current in the δ axis direction,
Lq is q-axis inductance,
Ld is d-axis inductance,
Rs is the armature winding resistance,
θe is an electrical angle error between the γ axis and the d axis.
iγRef is a current command in the γ-axis direction.

That is, when the current command value in the γ-axis direction is constant, the interference current amount fγ _s is an electrical angle error between the γ-axis and the d-axis from the equation (4) in the range of the rotor electrical angle 0 to 2π. θ _e reaches the maximum value when n · π / 2 + π / 4 (n = 0, 1, 2, 3). That is, although there is a maximum value of the interference current amount fγ _s for each electrical angle π / 2 of the rotor, it is only necessary to find the phase of the maximum value of the interference current amount fγ _s closest to the reference phase θ ₀ . The phase is shifted by Δθ in the range of the electrical angle 0 to π / 2 of the rotor from an arbitrary reference phase θ _0, and the interference current amount fγ _s for each phase is observed and stored, and the stored interference current amount fγ _s The phase having the maximum value is used as the magnetic pole position estimation start phase θ _S.
Further, Δθ is not required to be accurate because it is only necessary to avoid the case where the phase of θ _e is π / 2 as the magnetic pole position estimation start phase θ _S.

The invention described in claim 2 is a γ-axis current generation circuit that generates a step-like γ-axis current command, and a γ-axis voltage command that generates a γ-axis voltage command by inputting a difference between the γ-axis current command and a later-described γ-axis current iγ. An axis current control unit, a δ axis current control unit that generates a δ axis voltage command, a vector control unit that calculates a magnitude V * and an output phase θv of the voltage command from the γ axis voltage command and the δ axis voltage command, , An inverter unit that outputs a three-phase current to a permanent magnet type brushless motor from the magnitude V * of the voltage command and an output phase θv, and a three-phase that calculates a γ-axis current and a δ-axis current from the two phases of the three-phase current A two-phase conversion unit; and a γ-axis angle θγ and a magnetic pole position estimation start phase θS creation circuit that creates the γ-axis angle θγ and the magnetic pole position estimation start phase θS by inputting the γ-axis current command and the δ-axis current. A permanent magnet type brushless motor control device comprising:
The γ-axis angle θγ and the magnetic pole position estimation start phase θS creation circuit step the γ-axis current command for each phase shifted by Δθ in the range of the electrical machine angle of the rotor from 0 to 2π from an arbitrary reference phase θ0. A storage unit for observing an interference current generated in the δ-axis direction when given as an alternating current command, and calculating and storing an interference current amount fγs from the observed interference current according to equations (3) and (4) If, in the respective phases shifted by the [Delta] [theta], it is characterized in that the interference current amount fγs that the storage is equipped with a start phase estimator for a magnetic pole position estimation start phase θS phase having the largest.
fγs = | lim∫0∞iδdt | (3)
fγs = | ((Lq−Ld) / 2RS) · sin 2θe · iγRef | (4)
Where i δ is the interference current in the δ axis direction,
Lq is q-axis inductance,
Ld is d-axis inductance,
Rs is the armature winding resistance,
θe is an electrical angle error between the γ axis and the d axis.
iγRef is a current command in the γ-axis direction.
According to the permanent magnet type brushless motor control device having such a configuration, the initial magnetic pole position estimation method according to the present invention can be implemented, and the accuracy of magnetic pole position estimation is improved.

Thus, according to the present aspect, it sets the δ axis direction advanced electrical angle 90 ° from the γ axis and γ-axis arbitrarily in space coordinates, electrical angle 0 of the rotor from the arbitrary reference phase theta ₀ The amount of interference current fγ _s generated in the δ-axis direction when the current command in the γ-axis direction is given as a stepped alternating current command for each phase shifted by Δθ within a range of ˜π / 2 is observed. The maximum phase of the stored interference current amount fγ _s is set as the magnetic pole position estimation start phase θ _S , so that the initial magnetic pole estimation starts regardless of the electrical angle of the reference phase θ ₀ γ axis Can be fixed to the true magnetic axis d-axis or the −d-axis advanced 180 ° from the true magnetic axis, and the magnetic pole position estimation accuracy is improved.

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

1 is a conceptual block diagram of an initial magnetic pole position estimation method for a permanent magnet type brushless motor according to an embodiment of the present invention, FIG. 2 is a flowchart of the initial magnetic pole position estimation method for the brushless motor shown in FIG. 1, and FIG. FIG. 4 is a diagram showing the relationship between the γ-axis and the d-axis shown in FIG. 1, and FIG. 5 is a characteristic diagram showing the θ _e characteristic shown in FIG.
In Figure 1, a stepped γ-axis current command i? _Ref as shown in FIG. 3 for outputting the γ axis current generating circuit 1, a current i _u of the inverter section 5 for driving a brushless motor 8, i _v a current sensor or the like Is input to the γ-axis current control unit 2 to generate a voltage command vγ ^* .
On the other hand, the δ-axis current control unit 3 also generates a δ-axis direction voltage command vδ ^* from the difference between the δ-axis current command and the δ-axis current iδ, but the control system in the δ-axis direction is an open loop and the gain is 0. Therefore, vδ ^* = 0.
Next, the correction angle θ _e is determined from the γ-axis current command iγ _Ref and the δ-axis current i δ by the γ-axis angle θγ and the magnetic pole position estimation start phase θ _S creation circuit (abbreviated as “θγ · θ _s creation circuit”) 7. Then (see FIG. 4), the angle θγ of the γ axis is updated.
As a result, the magnitude V ^* of the voltage command and the output phase θ _v are given from the vector control unit 4 to the inverter unit 5, but because vδ ^* = 0, V ^* = | vγ ^* | and θV = θγ. .

Next, the operation will be described.
Referring to the flowchart of FIG. 2, first, the initial phase θγ is set to an arbitrary reference phase θ0 whose relative relationship with the magnetic pole of the motor is not known (S100).
Next, the current of at least two phases of the three-phase current of the permanent magnet type brushless motor 8, here, the U-phase current and the v-phase current (which may be other combinations) at K · T _s seconds (T _s Currents i _u (K) and i _v (K) of current loop sampling time) are input (S101).
Next, two-phase three-phase conversion is executed according to the position of the γ-axis from the α-phase (see FIG. 4) θγ (K) to derive iγ (K) and iδ (K) (S102).
Subsequently, fγ _s (t) = ∫iδdt is calculated based on the equation (3) (S103), and θγ (K) and fγ _s (t) at this time are stored (S104).
Next, the phase is updated by a predetermined phase update amount Δθ (S105), and the integral term of i δ is reset for the routine of S101 to S104 (S106).
Further, a current command for (K + 1) Ts seconds is created by a timer interrupt (S107).
As described above, the processing of S101 to S107 is repeated n times (S108).
Then, θγ (K) at the maximum value of fγ _s (t) stored in S104 is set to the magnetic pole position estimation start phase θ _S (S109).
Thereafter, a process of estimating the true magnetic pole of the motor is executed with reference to the phase θ _S set in S109.
The number of repetitions S108 is the number of times the rotor electrical angle 0 to π / 2 is engraved, and the phase update amount Δθ in S105 is also determined by the number of repetitions.
If it is assumed that n = 9 times and iδ integration time = 4 ms based on FIG. 3, the phase update amount Δθ is 20 deg each, and the magnetic pole position estimation start phase θ _S can be determined in 0.1 s or less.

As described above, according to the present invention, the γ-axis is arbitrarily set on the space coordinates, and the δ-axis is set in a direction advanced by 90 ° from the γ-axis, and the current control system in the γ-axis direction is configured in a closed loop. In addition, the current control system in the δ-axis direction is configured as an open loop, and the current command in the γ-axis direction with respect to each phase shifted from the arbitrary reference phase θ ₀ by Δθ in the range of the rotor electrical angle ₀ to 2π. Is observed and stored in the δ-axis direction when given as a stepped alternating current command, and the magnetic pole position estimation start phase θ _S is estimated in advance from the stored magnitude relation of the interference current. ing.
The amount of interference current fγ _s generated in the δ-axis direction when the current command in the γ-axis direction is given as a stepped alternating current command is defined as (3) and ( 4) It is characteristic that it is shown by Formula.
fγ _s = | lim∫ ₀ ∞iδdt | (3)
fγ _s = | ((L _q −L _d ) / 2R _S ) · sin 2θ _e · i γ _Ref | (4)
Where i δ is the interference current in the δ-axis direction, L _q is the q-axis inductance,
L _d is d-axis inductance, R _s is armature winding resistance,
θe is an electrical angle error between the γ-axis and the d-axis, and iγ _Ref is a current command in the γ-axis direction.

As described above, according to the present invention, the γ-axis is set in the spatial coordinate system and the δ-axis is set in a direction advanced from the γ-axis by an electrical angle of 90 deg. Compared to a method in which the control system is configured as an open loop and the initial magnetic pole position is detected by observing the interference current iδ generated in the δ direction when the current command iγ _Ref in the γ-axis direction is given as a stepped alternating current command. , the reference phase theta high speed can be detected magnetic pole position estimation starting phase theta _S regardless of _0, the reference phase theta ₀ to a true magnetic axis of the γ-axis regardless d-axis or the true magnetic axis from 180 ° advanced -d The establishment time until it matches the axis can be fixed, and the magnetic pole position estimation accuracy is improved.
In this way, since no additional sensor is required and the initial magnetic pole position can be detected at high speed and with high accuracy, it can be applied to applications that require torque accuracy from the start.

It is a conceptual block diagram of the initial magnetic pole position estimation method of the permanent magnet type brushless motor which concerns on embodiment of this invention. It is a flowchart of the initial magnetic pole position estimation method of the brushless motor shown in FIG. FIG. 2 is a waveform diagram of a γ-axis current command shown in FIG. 1. It is a figure which shows the relationship between the (gamma) axis | shaft and d-axis which are shown in FIG. It is the characteristic curve of (theta) _e and f (gamma) _s shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 γ-axis current generation circuit 2 γ-axis current control unit 3 δ-axis current control unit 4 Vector control unit 5 Inverter unit 6 Three-phase two-phase conversion unit 7 θγ, θ _s creation circuit 8 Brushless motor

Claims (2)

The δ axis is set arbitrarily in the spatial coordinates, and the δ axis is set in a direction advanced by 90 ° from the γ axis, and the current control system in the γ axis direction is configured in a closed loop and the current control system in the δ axis direction is opened. An interference current generated in the δ-axis direction when the current command in the γ-axis direction is given as a stepped alternating current command is observed, and an integral value of the interference current and a γ-axis current command value are A magnetic pole position estimation method for a permanent magnet type brushless motor that estimates a magnetic pole position based on a sign of a product,
First, the interference current is observed for each phase shifted by Δθ in the range of the rotor electrical angle of 0 to 2π from an arbitrary reference phase θ0, and from the observed interference current, the equations (3) and (4) ) To calculate and store the interference current amount fγs by
Of the phases shifted by Δθ, the phase at which the stored interference current amount fγs is maximum is defined as a magnetic pole position estimation start phase θS .
Thereafter, the magnetic pole position is estimated from the magnetic pole position estimation start phase θS, and the initial magnetic pole position estimation method for the permanent magnet type brushless motor is characterized.
fγs = | lim∫0∞iδdt | (3)
fγs = | ((Lq−Ld) / 2RS) · sin 2θe · iγRef | (4)
Where i δ is the interference current in the δ axis direction,
Lq is q-axis inductance,
Ld is d-axis inductance,
Rs is the armature winding resistance,
θe is an electrical angle error between the γ axis and the d axis.
iγRef is a current command in the γ-axis direction. A γ-axis current generation circuit for generating a step-like γ-axis current command, a γ-axis current control unit for generating a γ-axis voltage command by inputting a difference between the γ-axis current command and a γ-axis current iγ described later, and a δ-axis A δ-axis current control unit for generating a voltage command, a vector control unit for calculating a voltage command magnitude V * and an output phase θv from the γ-axis voltage command and the δ-axis voltage command, and a voltage command magnitude V * And an inverter part that outputs a three-phase current from the output phase θv to a permanent magnet brushless motor, a three-phase two-phase converter that calculates a γ-axis current and a δ-axis current from two phases of the three-phase current, and the γ Permanent magnet type brushless motor comprising a γ-axis angle θγ and a magnetic pole position estimation start phase θS creation circuit for creating a γ-axis angle θγ and a magnetic pole position estimation start phase θS by inputting an axis current command and the δ-axis current A control device,
The γ-axis angle θγ and the magnetic pole position estimation start phase θS creation circuit step the γ-axis current command for each phase shifted by Δθ in the range of the electrical machine angle of the rotor from 0 to 2π from an arbitrary reference phase θ0. A storage unit for observing an interference current generated in the δ-axis direction when given as an alternating current command, and calculating and storing an interference current amount fγs from the observed interference current according to equations (3) and (4) If, in the respective phases shifted by the [Delta] [theta], permanent magnet, characterized in that the interference current amount fγs that the storage is equipped with a start phase estimator for a magnetic pole position estimation start phase θS phase which maximizes Brushless motor control device.
fγs = | lim∫0∞iδdt | (3)
fγs = | ((Lq−Ld) / 2RS) · sin 2θe · iγRef | (4)
Where i δ is the interference current in the δ axis direction,
Lq is q-axis inductance,
Ld is d-axis inductance,
Rs is the armature winding resistance,
θe is an electrical angle error between the γ axis and the d axis.
iγRef is a current command in the γ-axis direction.

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