JPS61132096A - Controller for ac motor - Google Patents

Abstract

PURPOSE:To accurately control the phase of an AC motor by compensating the delay of a current command in a low pass filter by providing a function generator. CONSTITUTION:A function generator 60 obtain a correcting phase angle thetad corresponding to the rotating speed of a detecting motor. The angle thetad always coincides with a delay phase angle DELTAtheta varying in response to the rotating speed of the motor. The angle thetad is added by a calculator 52 together with a phase angle theta0 from a rotor position detector 30, a phase angle tan<-1>(i1d/i1q) from a calculator 50 and a load angle command from a calculator 40. Thus, the phase delay theta of the current command in a low pass filter 43 is compensated by the angle thetad.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an AC motor control device in which a drive if flow of an AC motor is controlled in accordance with a current command.

(Prior art and its problems) In this type of device, a stepped sine wave current command is obtained through digital processing using a microcomputer, etc., and conventionally, an AC motor is controlled according to this command as follows. It was done.

FIG. 4 shows a conventional device used in an electric vehicle, in which the DC output 'III current of the vehicle battery 10 is PWM.
The PWM inverter main circuit 12A of the inverter 12 converts the current into a three-phase alternating current.

And that alternating current is driving! 1JTi flow is supplied to the synchronous motor 14, and the synchronous motor 14 is used as a driving source for the vehicle.

In this device, power transistors are used for each main switching element of the PWM inverter main circuit 12A, and these transistors are switched and driven by a driver circuit 12B.

This switching drive is performed by P of the PWM circuit 12C-.
The PWM signal is obtained based on the current control signal obtained by the current control circuit 1201'.

Roughly speaking, the current control circuit 12D obtains a current control signal based on the current command, and a detection signal of the motor drive current detected by the current detection 1115 is supplied to the current control circuit 12 as a feedback signal.

Here, the current command is obtained by a current command generator 36, and the current command is generated by digital processing using a microcomputer or the like.

The current command generator 36 is supplied with a motor rotation speed detection signal from a speed sensor 37, a rotor rotation detection signal from a rotation sensor 28, and a torque command from a torque command generator 32. A current command is being generated.

This current command is a stepped sine wave as shown by the characteristic 10o in FIG. occurs, so by removing the harmonic components of the current command with the low-pass filter 43, the command 100 is made into a sinusoidal current command 102 shown by the characteristic 102 in FIG.

However, in this type of conventional device, as can be understood from FIG. 5, the phase of the command 102 is delayed by the phase angle Δθ by the low-pass filter with respect to the command 100, so accurate phase control cannot be performed. In particular, the conventional device shown in FIG. 4 has a problem in that the load angle decreases and the motor torque corresponding to the torque command cannot be obtained.

As can be understood from FIGS. 6 and 7, the phase angle Δθ increases according to the rotational speed of the rotor, so the error in the phase control increases as the rotor rotates at high speed. Ta.

(Object of the invention) The present invention has been made in view of the above-mentioned conventional problems,
The purpose is to control the phase of all by the low-pass filter.
An object of the present invention is to provide an AC motor control device that can eliminate errors.

(Structure of the Invention) In order to achieve the above object, the present invention includes: current command generation means for generating a stepped sinusoidal current command to be applied to an AC motor based on a torque command; and removing high frequency components of the current command. In the AC motor control rB device having a low-pass filter, the current command generating means includes: a phase delay compensating means for compensating for a phase delay of the current command caused by the low-pass filter according to the rotational speed of the AC motor. do.

(Embodiments of the Invention) Hereinafter, preferred embodiments of the apparatus according to the present invention will be described based on the drawings.

In Fig. 1, the DC output current of the on-vehicle valve 10 is PW.
It is converted into a three-phase alternating current by an M inverter 12, and the alternating current is supplied as a drive current to a permanent magnet disk synchronous motor 14.

FIG. 2 shows a side cross section of the permanent 11-stone disc type synchronous motor 14, and its rotating shaft 16 has a rotor 1B.
and a permanent magnet 20 are fixed.

The rotor 18 is made up of magnetically permeable materials formed in a substantially tray shape that are opposed to each other, and a magnetic circuit 22 is formed by the magnetomotive force of a permanent magnet 20 inserted between the two.

Furthermore, a stator 24 is inserted into a gap formed on the circumferential side of the rotor 18, and a motor torque is generated by the flow of a current 26, and a reaction force is applied to the rotor 18.
is rotated.

Further, the rotation of the rotor 18 is detected by the rotation sensor 28, and the rotor rotation angle θ0 is detected by the rotor position detector 30 shown in FIG. 1 by monitoring the detection signal.

In FIG. 1, this device is provided with a torque command generator 32 and a magnetic flux command generator 34, whose torque command T 63 and magnetic flux command Φ are supplied to a divider 38.

In this W divider 38, the torque component current command i1d is determined by the calculation process of equation (1): i+d=T/Φ.

Note that the torque command generator 32 performs delay processing on the detected value of the accelerator pedal depression amount, thereby making it possible to soft start the vehicle, and the magnetic flux command generator 34 performs delay processing on the detected value of the accelerator pedal depression amount, and the magnetic flux command generator 34 uses the sensor 37 based on the speed-magnetic flux characteristic. A magnetic flux command Φ corresponding to the motor rotational speed detection signal is determined, and so-called field weakening control of the motor 14 is performed using this command.

The command i1d is supplied to a computing unit (inverse sine function generator) 40, and the computing unit (inverse sine function generator) 40 calculates the primary inductance L of the permanent magnet disk type synchronous motor 14 and the effective magnetic flux φ of the permanent magnet. With this command i1d, the load angle command δ becomes δ-5in'(1-/φ-i'd
)-sin' (L/φ-T/φ)... determined by the calculation process of equation (2).

The command δ obtained by the arithmetic unit (inverse sine function generator) 40 is supplied to the arithmetic unit (inverse cosine function generator) 42, where the value φC
OSδ is required.

The value φCOSδ is subtracted from the command Φ' in the arithmetic unit 44, and this subtraction value is supplied to the arithmetic unit n546.

In the computing unit 46, the magnetic flux component current command 11q is calculated using the pull vltll of the computing unit 44 and the primary inductance L of the permanent magnet disk type synchronous motor 14 as i + Q = (
Φ−φCOSδ)/L ... It is determined by Equation (3).

Furthermore, the above magnetic flux component current command i+Q and torque component i
! The flow command i1d is supplied to an arithmetic unit 48 and an arithmetic unit (tangent inverse function generator) 50.

In this calculator 48, the current amplitude command C-q? +1l
d2 is obtained, and the arithmetic unit 50 calculates the phase angle tab'
(i Id/i +Q) is required.

Further, the phase angle tan' (i+d/i+Q) is calculated by the computing unit 52 along with the load angle command δ and the rotor detection rotation angle θa.
In this arithmetic unit 52, the phase angle command θ is determined by θ=θ0+δ+θ1...Equation (4).

This phase angle command θ is supplied to a vector multiplier 54 together with the current amplitude command 11, and in this vector multiplier 54, current commands iu, iv,
iw is iu se 11q'+1 1'5in(
θ 0 + δ + θl)...Equation (5) %Equation % 1+2π/3)...Equation (6) iw= zq +++ 5in(θ+δ+θ1
+4π/3) ... determined by equation (7).

Note that in this vector multiplier 54, the values sinθ,
sin (θ+2π/3) is first determined, then the command iu= IIQ +++ , Sfnθ, iv
-Ilq +++ 5in (θ+2π/3) is obtained, and finally the command iv=l+q -zId2si
n (θ4-2π/3) gives the command iw-(T”DingT
7+1Id2sin(θ+4/37r) Kakume'3
I'm going to try it.

These current commands iu, iv, iw are supplied to the PWM inverter 12 via the low-pass filter 43, and three-phase alternating currents corresponding to these current commands iu, iv, iw are used as driving currents to drive a permanent magnet disk type motor. It is supplied to the synchronous motor 14.

Here, the current command generator 36 is provided with a function generator 60, and a motor rotation speed-correction phase angle characteristic is set in this function generator 60.

The motor rotation speed detection signal from the speed sensor 37 is supplied to the function generator 60, and the corrected phase angle θd corresponding to the detected motor rotation speed is obtained from the above characteristics.

Furthermore, this corrected phase angle θd matches the delayed phase angle Δθ of the low-pass filter 43, and the phase angle θ, ), jan-'(ild/i+Q),
It is added to δ.

As described above, in this embodiment, the phase angle command θ is advanced by the phase angle θd.

This embodiment has the above configuration, and its operation will be explained below.

As can be understood from the explanation of the permanent magnet disk type synchronous motor 14 in FIG.
The relationship is reversed.

Here, when the two-pole model shown in FIG. 3 is assumed for the permanent magnet disk type synchronous motor 14, the torque is generated as follows.

In Figure 3, the coordinates (q, d) are the effective magnetic flux Φ^
The magnetic flux φ^ is obtained by the permanent magnet.

At this time, the magnetic flux components in each direction are as follows: Φ＾−φ^cosδ+Li+Q ...Equation (8) θ−φsinδ+L i 1d ...(9th
) can be expressed by the following formula.

And the torque T^ generated by this motor is T^-Φx
-i+d...M It is possible to express by the formula (,10).

□ Therefore, when the torque command T and the magnetic flux command Φ are given, the equation (1) can be obtained from the equation (10), and the command i+d can be obtained from this equation.

Further, the load angle command δ can be obtained from the equations (10) and (1).

Furthermore, the above-mentioned equation (3) is obtained from the above-mentioned equation (8), and the command ilq is obtained from this equation.

Since these commands i+q and i+cl are orthogonal, their vector absolute value becomes the current amplitude command 11, and this command 1
1 corresponds exactly to the torque command T.

Also, the phase angle at that time is the rotor rotation angle and load angle.

Then, since it is the sum of the phase angles, if the phase angle command θ obtained by the above equation (4) is used together with the current amplitude command 11 to calculate the current command i, it will accurately match the torque command T. A torque T^ is generated in the permanent magnet disk type synchronous motor 14, and the torque T^ does not lag behind the command T.

Therefore, as in this embodiment, the current command iu is determined by the equations (5), (6), and (7).

When iv and iw are given to the PWM inverter 12,
Motor control with extremely high responsiveness and efficiency becomes possible, and motor controllability is significantly improved.

Here, from the vector multiplier 54 to the PWM inverter 12
When the current command is supplied to the original command 100, the command 102 is delayed by the phase angle Δθ in the low-pass filter 43 as described above, but in this embodiment, the delayed phase angle coincides with the delayed phase angle Δθ.

The phase angle (command) θ of the original command 100 is advanced by the phase angle θd.

That is, the numerical value generator 60 obtains a corrected phase angle θd corresponding to the detected motor rotation speed, and this phase angle θd
always matches the delay phase angle Δθ, which changes depending on the motor rotation speed.

The corrected phase angle θd is the phase angle θ. , tan(i
+d/i+Q), is added together with δ to obtain the phase angle (command)
θ is advanced by this corrected phase angle θd.

Therefore, the phase delay Δθ of the current command in the low-pass filter 43 is compensated by the corrected phase angle θ.

Therefore, the synchronous motor 14 is operated at the initial phase angle, and as a result, the load angle control is performed accurately and a torque corresponding to the torque command T is obtained in the synchronous motor 14.

As explained above, according to this embodiment, since the phase delay of the current command in the low-pass filter is compensated for, accurate motor phase control is possible. 1 in 14! P is received.

(Effects of the Invention) As described above, according to the present invention, the delay in the current command in the low-pass filter is compensated for, so that accurate phase control of the AC motor becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a device to which the present invention is applied, and FIG. 2 is a diagram of a permanent magnet disk type synchronous motor. The side sectional view, Figure 3, shows the permanent magnet disk type synchronous motor.
Figure 4 is an explanatory diagram of the configuration of the conventional device;
6 and 7 are waveform diagrams illustrating the phase delay effect of the current command in the low-pass filter. 12・・・・・・・・・PWM inverter 14・
...... Permanent magnet disk type synchronous motor 28 ...... Rotation sensor 30 ...
......Rotor position detector 32...
...Torque command generator 34...
...Magnetic flux command generator 36...Current command generator 37... Speed sensor 4
3・・・・・・・・・・・・Low pass filter 50.5
2... Arithmetic unit

Claims (1)

[Claims] (1) An AC motor control device comprising: current command generation means for generating a stepped sinusoidal current command to be applied to an AC motor based on a torque command; and a low-pass filter for removing high frequency components of the current command; An AC motor control device characterized in that the command generation means includes a phase delay compensating means for compensating for a phase delay of the current command caused by the low-pass filter according to a rotational speed of the AC motor.