JP2003164191A - Control device for permanent magnet synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To discriminate a magnetic pole of a permanent magnet synchronous motor without utilizing magnetic saturation. <P>SOLUTION: A control device comprises a q-axis pulse current controller 6 which controls the current of the permanent magnet synchronous motor 2, assuming an estimated d-axis current instruction as zero and an estimated q-axis current instruction as a predetermined value, upon converging a phase difference 0 degree or 180 degrees by a d-axis estimator 3 after starting; and a q-axis pulse magnetic pole discriminator 71 which changes an estimated d-axis phase θ of the output of the d-axis estimator 3 by 180°, when the sign of the estimated d-axis voltage component applied to the permanent magnet synchronous motor 2, while the q-axis pulse current controller 6 is operated, is the same as the sign of q-axis current instruction of the q-axis pulse current controller. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for estimating a d-axis which is a direction of a permanent magnet in a controller for a permanent magnet synchronous motor without a position sensor.

[0002]

2. Description of the Related Art FIG. 6 is an example of a block diagram for controlling the torque of a permanent magnet synchronous motor. Hereinafter, description will be given with reference to FIG. The power converter 1 supplies power to the permanent magnet synchronous motor 2 based on the input signal S. The d-axis estimator 3 is
From the input current i and the input voltage v of the permanent magnet synchronous motor 2,
Assuming that the phase of the N pole of the permanent magnet of the rotor of the permanent magnet synchronous motor 2 (hereinafter referred to as d axis) is θr and the phase of the estimated direction (hereinafter estimated d axis) is θ, the phase difference Δθ = θr−θ Estimating that the phase difference can be converged to 0 degree when the initial value of the absolute value is less than 90 degrees, and the phase difference can be converged to 180 degrees when the initial value of the phase difference is 90 degrees or more. The phase θ of the d axis is output. The torque controller 4 converts the current S of the permanent magnet synchronous motor 2 based on the estimated d-axis phase θ into an estimated d-axis component and a component in the direction perpendicular to the estimated d-axis (hereinafter, estimated q-axis) for power conversion. The output torque of the permanent magnet synchronous motor 2 is made to follow the torque command Tref.

The principle by which the d-axis estimator 3 can estimate the d-axis phase will be described below. The characteristic formula of the permanent magnet synchronous motor is represented by [Equation 1]. Here, the estimated d axis is represented by the γ axis, and the estimated q axis orthogonal to the estimated d axis is represented by the δ axis.

[0004]

[Equation 1]

Ld is the d-axis inductance, Lq
Is the q-axis inductance, and R is the winding resistance. p represents a time derivative, ω is a rotational angular frequency, and φ is a magnetic flux generated by a permanent magnet. Further, iγ and iδ are currents of the γ-axis and δ-axis components, respectively, and vγ and vδ are voltages of the γ-axis and δ-axis components, respectively. In the second line of equation (1), (2), (3),
Substituting equation (4), cos (2 · Δθ) = 1, sin
When approximated as (2 · Δθ) = 2 · Δθ, as shown in [Equation 2],

[0006]

[Equation 2]

Is obtained. Adjust the estimated d-axis phase θ,
The d-axis phase can be estimated by the d-axis estimator 3 by setting the phase error Δθ in the equation (5) to zero.

However, as shown in the equations (3), (4) and (5), the phase error Δθ is used by being doubled. Therefore, in these equations, the phase error is 180 degrees and the phase error is 0 degree. Can not be distinguished. That is, if the absolute value of the initial phase error is less than 90 degrees, the phase error can be set to 0 degree by adjusting θ so that Δθ obtained by the equation (5) becomes 0. If the absolute value of the error exceeds 90 degrees, the phase error will converge to 180 degrees. Since normal torque control cannot be performed with this, when starting
As shown in FIG. 6, first, the d-axis is estimated, then the magnetic pole is determined, and then the normal operation shown in FIG. 6 is performed. The magnetic pole discrimination is to determine whether the phase error is 180 degrees or 0 degrees,
In the case of 0 degree, it is a means for correcting θ to 180 degrees so that the phase error becomes 0 degree. Conventionally, this magnetic pole discrimination is performed by the method shown in the block diagram of FIG. 5, and the following description will be made with reference to FIG.

The d-axis pulse generator 9 applies a rectangular wave voltage alternating in the direction of the phase θ estimated by the d-axis estimator 3 and in the opposite direction to the permanent magnet synchronous motor 2 via the power converter 1. To do. The d-axis pulse magnetic pole discriminator 8 sets ΔI1 to the absolute value of the slope of the current at the last time when the d-axis pulse generator 9 applies the voltage in the θ direction, and determines the last value when the voltage is applied in the reverse direction of θ. When the current gradient at the time point is ΔI2, ΔI2
When> ΔI1, the phase error is determined to be 180 degrees, and the command signal C for correcting θ by 180 degrees is output to the d-axis estimator 3. When the signal C is input, the d-axis estimator 3 corrects the output θ by 180 degrees.

At the time when ΔI1 is measured when the phase error is 0 degree, the magnetic flux inside the permanent magnet synchronous motor 2 is
The sum of the magnetic flux of the permanent magnet and the magnetic flux of the windings causes magnetic saturation, resulting in a smaller inductance. On the contrary, when ΔI2 is measured when the phase error is 0 degree, the magnetic flux inside the permanent magnet synchronous motor 2 becomes the difference between the magnetic flux of the permanent magnet and the magnetic flux due to the winding, so that the magnetic saturation is relaxed and the inductance is reduced. Grows. Therefore, ΔI2 <ΔI1
Becomes However, when the phase error is 180 degrees, the above description is completely reversed, and therefore ΔI2> ΔI1. That is, if ΔI2> ΔI1, the phase error is found to be 180 degrees.

As described above, the d-axis estimator 3 has a phase error of 1
Although it may converge to 80 degrees, it is possible to correct the phase error to 0 degree by correcting it by the magnetic pole discrimination as shown in FIG. 5 at the time of starting, and with the configuration of FIG. It becomes possible to control.

[0012]

As described above, as shown in FIG.
In the magnetic pole discrimination shown in (1), the magnetic saturation phenomenon of the permanent magnet synchronous motor is used. However, when the gap between the rotor and the stator of the permanent magnet synchronous motor is large, or when a current that causes magnetic saturation cannot flow due to insufficient current capacity of the power converter 1, magnetic saturation does not occur, and FIG. With the conventional method shown in FIG. 2, accurate magnetic pole discrimination cannot be performed.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in claim 1, the direction of the N pole of the permanent magnet of the rotor of the permanent magnet synchronous motor (hereinafter d).
The initial value of the absolute value of the phase difference θr−θ is 9 where θr is the phase of the axis) and θ is the phase of its estimated direction (hereinafter, the estimated d axis).
If the phase difference is within 0 degrees, the phase difference can be converged to 0 degree, and if the initial value of the phase difference is 90 degrees or more, the estimated phase θ of the d-axis is converged to 180 degrees. A d-axis estimator that outputs the current of the permanent magnet synchronous motor and a component of the estimated d-axis and a direction perpendicular to the component (hereinafter estimated q-axis)
In a controller for a permanent magnet synchronous motor, which comprises a torque controller that controls the divided d-axis components, the estimated d-axis is adjusted after the phase difference is converged to 0 degree or 180 degrees by the d-axis estimator after starting. Of the estimated q
A q-axis pulse current controller that controls the current of the permanent magnet synchronous motor with a current command for the axis as a predetermined value, and the estimated d-axis applied to the permanent magnet synchronous motor while the q-axis pulse current controller is operating. When the sign of the voltage component (hereinafter referred to as the d-axis voltage) is the same as the sign of the q-axis current command of the q-axis pulse current controller, the estimated θ-axis phase θ that is the output of the d-axis estimator
And a first q-axis pulse magnetic pole discriminator that changes the angle by 180 degrees.

In the present invention, the d-axis voltage integrator for time-integrating the d-axis voltage while the q-axis pulse current controller is operating, and the absolute value of the d-axis voltage integrated value of the output of the d-axis voltage integrator are absolute. When the sign of the d-axis voltage integrated value is the same as the sign of the q-axis current command of the q-axis pulse current controller when the value exceeds a predetermined value, the estimated d-axis phase that is the output of the d-axis estimator and a second q-axis pulse magnetic pole discriminator that changes θ by 180 degrees.

In the third aspect, the d-axis voltage Vd1 after a lapse of a predetermined time t1 from the start of the operation of the q-axis pulse current controller and the d after a lapse of a predetermined time t2 from the time point t1.
The axis voltage Vd2 is measured, and when the sign of Vd2-Vd1 is the same as the sign of the q-axis current command of the q-axis pulse current controller, the phase θ of the estimated d-axis that is the output of the d-axis estimator is 18
And a third q-axis pulse magnetic pole discriminator that changes 0 degree.

In the present invention, the d-axis voltage is time-integrated with an initial value of 0 for each predetermined minute cycle Δt, and the minute time d is output.
The output φd1 of the minute d-axis voltage integrator after a lapse of a predetermined time t3 from the start of the operation of the axis voltage integrator and the q-axis pulse current controller is stored, and the minute time d-axis voltage is stored for each cycle Δt. It is judged whether or not the absolute value of the difference between the output φdn of the integrator and the φd1 exceeds a predetermined value, and at the time when the absolute value of the difference is subtracted from the φdn from the φd1, the sign is the q-axis of the q-axis pulse current controller. When the sign of the current command is the same, the estimated d-axis phase θ output from the d-axis estimator is 18
And a fourth q-axis pulse magnetic pole discriminator that changes 0 degree.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention according to claim 1 is shown in FIG. 1 and will be described based on this drawing. This figure shows the magnetic pole discrimination in place of FIG. 5 described in the prior art, and is executed at the time of the magnetic pole discrimination in FIG. 7. The q-axis pulse current controller 6 is a current command of the estimated d-axis component in the phase θ direction estimated by the d-axis estimator 3 (hereinafter, the estimated d-axis current command).
Is 0 and the current command of the estimated q-axis component perpendicular to the estimated d-axis (hereinafter, estimated q-axis current command) is set to a predetermined value I, and the power converter 1
The current control of the permanent magnet synchronous motor 2 is performed via. First
The q-axis pulse magnetic pole discriminator 71 includes the q-axis pulse current controller 6
When the sign of the estimated d-axis voltage component (hereinafter referred to as the d-axis voltage) applied to the permanent magnet synchronous motor 2 during operation is the same as the sign of the q-axis current command of the q-axis pulse current controller 6, the d-axis estimator Three
The command C for changing the estimated phase θ of the d-axis, which is the output of, by 180 degrees is output. When the signal C is input, the d-axis estimator 3 corrects the output θ by 180 degrees.

In equation (1), the estimated d axis is the γ axis, and the estimated d axis is
Since the estimated q axis orthogonal to the axis is represented as the δ axis,
By the q-axis pulse current controller 6, iγ = 0 and iδ = I, and since the respective DC amounts, the differential term becomes 0, so Δθ
Is 0 degrees or 180 degrees, the first line of equation (1) is [Equation 3]
It is expressed by the formula.

[0019]

[Equation 3]

If Δθ = 0 degrees, and if I> 0, the permanent magnet synchronous motor 2 generates a torque in the positive direction.
The permanent magnet synchronous motor 2 accelerates in the positive direction. That is ω
> 0 and the d-axis voltage vγ <0 from the equation (6). That is, the d-axis voltage vγ has the opposite sign to the estimated q-axis current command, and the first q-axis pulse magnetic pole discriminator 71 does not output the 180-degree change command C. In the case of Δθ = 180 degrees, if I> 0, the permanent magnet synchronous motor 2 generates torque in the negative direction, so the permanent magnet synchronous motor 2 accelerates in the negative direction. That is, ω <0 and the d-axis voltage vγ> 0 is obtained from the equation (6).
That is, the d-axis voltage vγ has the same sign as the estimated q-axis current command I, and the first q-axis pulse magnetic pole discriminator 71 outputs the 180-degree change command C, and Δθ = 0 can be set.

An embodiment of the invention according to claim 2 is shown in FIG. 2, which will be described below with reference to FIG.
The description of the same items as those will be omitted. The d-axis voltage integrator 10 time-integrates the d-axis voltage during operation of the q-axis pulse current controller 6 and outputs it. Second q-axis pulse magnetic pole discriminator 72
Is the sign of the q-axis current command of the q-axis pulse current controller 6 when the absolute value of the d-axis voltage integrated value of the output of the d-axis voltage integrator 10 exceeds a predetermined value. When the same as the above, the estimated d-axis phase θ which is the output of the d-axis estimator 3 is
A command C for changing 0 degree is output.

The principle of magnetic pole discrimination by the second q-axis pulse magnetic pole discriminator 72 is as follows.
Same as 1, but d in the first q-axis pulse magnetic pole discriminator 71
While the sign of the axial voltage vγ is used, the sign of the time integral value of the d-axis voltage vγ is used in the second q-axis pulse magnetic pole discriminator 72. Therefore, when the d-axis voltage vγ has a high frequency component or a noise component due to the power converter 1, the first q-axis pulse magnetic pole discriminator 71 is likely to erroneously detect the sign of the d-axis voltage vγ. However, in the second q-axis pulse magnetic pole discriminator 72, it is possible to reduce the possibility of erroneous detection of the code by using the integrated value in which the high frequency component is suppressed.

An embodiment of the invention according to claim 3 is shown in FIG. 3, which will be described below with reference to FIG.
The description of the same items as those will be omitted. The third q-axis pulse magnetic pole discriminator 73 sets the d-axis voltage to Vd1 after a predetermined time t1 has elapsed since the q-axis pulse current controller 6 started to operate,
The d-axis voltage after a lapse of a predetermined time t2 from the time point t1 is Vd
2, when the sign of Vd2-Vd1 is the same as the sign of the q-axis current command I of the q-axis pulse current controller 6, the d-axis estimator 3
The command C for changing the estimated phase θ of the d-axis, which is the output of, by 180 degrees is output.

Since the magnetic pole discrimination in the configuration of FIG. 1 is equivalent to the magnetic pole discrimination in the rotational direction in which the q-axis pulse current controller 6 is operating, the q-axis pulse current controller 6 is started from the state where the electric motor 2 is stopped. Is assumed to start operating, and if the electric motor 2 is already rotating when the q-axis pulse current controller 6 starts operating, the magnetic pole determination will be incorrect. Claim 3 shown in FIG. 3 solves this problem, and magnetic pole discrimination is performed by a change in speed during operation of the q-axis pulse current controller 6. Since the d-axis voltage vγ is proportional to the speed ω as shown in the equation (6),
It is possible to know the speed from the magnitude of the d-axis voltage. Therefore, in the third q-axis pulse magnetic pole discriminator 73, it is possible to know the direction of speed change by the sign of the difference between the d-axis voltage Vd1 at time t1 and the d-axis voltage Vd2 at time t2.
When I> 0 and Δθ = 0 degree, the electric motor 2 outputs a positive torque, and therefore the change in speed should be positive.
When θ = 180 degrees, the electric motor 2 outputs a negative torque, so the change in speed becomes negative. Therefore, when the change in speed is negative, that is, when Vd2-Vd1> 0, it is necessary to correct Δθ by 180 degrees.

An embodiment of the invention according to claim 4 is shown in FIG. 4, which will be described below with reference to FIG.
The description of the same items as those will be omitted. The minute time d-axis voltage integrator 11 time-integrates the d-axis voltage at an initial value 0 for each predetermined minute period Δt and outputs the d-axis voltage. The fourth q-axis pulse magnetic pole discriminator 74 stores the output φd1 of the d-axis voltage integrator 11 for a minute time after a predetermined time t3 has elapsed since the q-axis pulse current controller 6 started to operate, and for each cycle Δt, a minute time. It is determined whether or not the absolute value of the difference between the output φdn of the d-axis voltage integrator 11 and the φd1 exceeds a predetermined value, and when it exceeds, φdn
When the sign of −φd1 is the same as the sign of the q-axis current command I of the q-axis pulse current controller 6, the command C for changing the estimated d-axis phase θ, which is the output of the d-axis estimator 3, is output by 180 degrees.

In FIG. 1 according to claim 1, as described above, there are two problems, that is, erroneous detection of magnetic pole discrimination due to noise and the like, and erroneous detection of magnetic pole discrimination due to rotation of the electric motor, and only the former problem is solved. FIG. 2 according to claim 2 is intended to solve the problem, and FIG. 3 according to claim 3 is intended to solve only the latter problem. FIG. 4 according to claim 4 solves both of the problems described above. Minute time d-axis voltage integrator 1
By using 1 output, the former problem is solved by the effect of suppressing high frequency noise components by integration, and the direction of change in speed is known from the direction of change in the output of the d-axis voltage integrator 11 for a minute time by the same principle as in FIG. It is possible and the latter problem has been solved.

[0027]

According to the present invention, since the magnetic poles can be discriminated without utilizing the magnetic saturation phenomenon, for example, when the gap between the rotor and the stator of the permanent magnet synchronous motor is large, or the current capacity of the power converter is insufficient. When a large current cannot flow, the magnetic pole can be discriminated even if the magnetic saturation phenomenon does not occur.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the invention according to claim 1.

FIG. 2 is a block diagram showing an embodiment of the invention according to claim 2;

FIG. 3 is a block diagram showing an embodiment of the invention according to claim 3;

FIG. 4 is a block diagram showing an embodiment of the invention according to claim 4;

FIG. 5 is a block diagram showing magnetic pole discrimination according to a conventional technique.

FIG. 6 is a block diagram showing a normal operation of a permanent magnet synchronous motor.

FIG. 7 is a flowchart at the time of starting the permanent magnet synchronous motor.

[Explanation of symbols]

1 ... Power converter 2 ... Permanent magnet synchronous motor 3 ... d-axis estimator 4 ... Torque controller 6 ... q-axis pulse current controller 71 ... 1st q-axis pulse magnetic pole discriminator 72 ... Second q-axis pulse magnetic pole discriminator 73 ... Third q-axis pulse magnetic pole discriminator 74 ... 4th q-axis pulse magnetic pole discriminator 8 ... d-axis pulse magnetic pole discriminator 9 ... d-axis pulse generator 10 ... D-axis voltage integrator 11. Micro time d-axis voltage integrator

Claims (4)

[Claims] 1. A phase difference θr−θ, where θr is the phase in the direction of the N pole of the permanent magnet of the rotor of the permanent magnet synchronous motor (hereinafter, d axis), and θ is the phase in the estimated direction (hereinafter, estimated d axis).
When the initial value of the absolute value of is within 90 degrees, the phase difference is set to 0.
The initial value of the phase difference is 90
If it is equal to or more than 0 degree, a d-axis estimator that outputs an estimated d-axis phase θ that converges the phase difference to 180 degrees, a current of the permanent magnet synchronous motor, and a component of the estimated d-axis and a direction perpendicular thereto ( In a controller for a permanent magnet synchronous motor, which comprises a torque controller that controls each component of an estimated q-axis below, after the phase difference is converged to 0 degree or 180 degrees by the d-axis estimator after starting, , The estimated d-axis current command is 0 and the estimated q-axis current command is a predetermined value to control the current of the permanent magnet synchronous motor, and the q-axis pulse current controller is operating. If the sign of the estimated d-axis voltage component (hereinafter referred to as d-axis voltage) applied to the permanent magnet synchronous motor is the same as the sign of the q-axis current command of the q-axis pulse current controller, the d-axis estimator The estimated d-axis of the output Controller for a permanent magnet synchronous motor, characterized by comprising a first 1q axis pulse pole discriminator to change the phase theta 180 deg. 2. A d-axis voltage integrator for time-integrating the d-axis voltage during operation of the q-axis pulse current controller, and an absolute value of a d-axis voltage integrated value output from the d-axis voltage integrator is predetermined. When the sign of the d-axis voltage integrated value is the same as the sign of the q-axis current command of the q-axis pulse current controller when the value exceeds the value, the estimated d-axis phase θ which is the output of the d-axis estimator is 180. 2. The controller for a permanent magnet synchronous motor according to claim 1, further comprising a second q-axis pulse magnetic pole discriminator that changes the degree. 3. The d-axis voltage Vd1 and the t-axis after a lapse of a predetermined time t1 from the start of the operation of the q-axis pulse current controller.
The d-axis voltage Vd2 after a lapse of a predetermined time t2 from time 1 is measured, and when the sign of Vd2-Vd1 is the same as the sign of the q-axis current command of the q-axis pulse current controller, the output of the d-axis estimator 3. The controller for a permanent magnet synchronous motor according to claim 1, further comprising a third q-axis pulse magnetic pole discriminator that changes the estimated d-axis phase θ by 180 degrees. 4. A minute time d-axis voltage integrator for time-integrating and outputting the d-axis voltage at an initial value of 0 for each predetermined minute cycle Δt, and a predetermined time t3 after the q-axis pulse current controller starts operating. Output φ of the d-axis voltage integrator for the minute time after the passage
d1 is stored, and it is determined whether or not the absolute value of the difference between the output φdn of the d-axis voltage integrator and the φd1 for a minute time exceeds a predetermined value for each period Δt, and when it exceeds, the φdn
The fourth q-axis for changing the phase θ of the estimated d-axis, which is the output of the d-axis estimator, by 180 degrees when the sign of the value obtained by subtracting φd1 from the same as the sign of the q-axis current command of the q-axis pulse current controller The controller for a permanent magnet synchronous motor according to claim 1, further comprising a pulse magnetic pole discriminator.