JPH08298796A - Method and device for controlling permanent magnet type electric motor - Google Patents

Abstract

PURPOSE: To accurately control the torque of a permanent magnet type electric motor in a simple control configuration. CONSTITUTION: A square wave current with 120 deg. conduction width is supplied from an inverter 10 to an electric motor 1, the current level of the electric motor 1 is detected by a three-phase full-wave rectification circuit 7, and a voltage command V1 * is given from a current regulator 9 to an inverter 10 so that the current detection value i1 matches a current command absolute value i1 * which is the level of the vector sum of a magnetization current command id * and a torque current command iq *. Also, a phase command θv * is obtained from the magnetization current command id * and the torque current command iq * and a value obtained by adding a phase compensation command Δθv * obtained as a function of an electric motor speed ω is added to it is given to the inverter 10, thus controlling the level and phase of the terminal voltage of the electric motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a permanent magnet type electric motor for PW.
A technique of supplying an equivalent three-phase electric motor current from an M-type inverter and controlling the magnitude and phase of the electric motor current based on a torque current command and a magnetizing current command, and performing highly accurate torque control with a particularly simple control configuration. It was devised so that it could be done.

[0002]

2. Description of the Related Art With reference to FIG. 4, a conventional representative permanent magnet type motor controller will be described. In this conventional control device, an equivalent three-phase current is supplied from an inverter 30 to a three-phase permanent magnet type electric motor (PM motor: hereinafter also simply referred to as an electric motor) 1 to detect a torque current detection value i _q and a magnetization current detection value i.
By feeding back _d , the three-phase voltage commands Vu ^* , Vv ^* , Vw are calculated from the torque current command i _q ^* and the magnetizing current command i _d ^*.
* Is made and the three-phase voltage command is given to the PWM modulation section 31 of the inverter 30 to control the magnitude and phase of the motor terminal voltage, thereby making the magnitude and phase of the motor current a desired value and improving the accuracy of torque control. I am trying to Reference numeral 33 indicates a DC power source.

Therefore, in the conventional device, in addition to the PWM inverter 30, the current control unit 34 and the current transformers 35 and 36 are provided.
The AD converters 37 and 38, the encoder 39, the position calculator 40, the coordinate converters 41 and 42, the magnetic flux weakening calculator 43, and the speed calculator 44.

Further, the inverter 30 is a sine wave approximation PWM.
A PWM modulator 31 such as a square or square wave approximate PWM type,
It is composed of the main circuit section 32. As is well known, PWM is pulse width modulation.

The current control section 34 uses an electric motor as a current command.
Rotation based on the magnetic flux axis that rotates in synchronization with the rotor of machine 1.
Torque current command expressed in transposed coordinate system (dq coordinate system)
i_q ^*And magnetizing current command i_d ^*And given that the current
Torque current detection expressed in the same rotating coordinate system as the detected value
Outgoing price i_qAnd magnetizing current detection value i_dAnd are given.

As is well known, the magnetizing current is a parallel component of the motor current with the magnetic flux axis (d axis), and the torque current is a parallel component of the torque axis (q axis) orthogonal to the magnetic flux axis ( In other words, it is a component orthogonal to the magnetic flux axis).

The current controller 34 controls the torque current command i _q ^*.
And integral between the torque current detection value i _q and proportional deviation (PI)
The torque voltage command V _q in the rotating coordinate system is calculated by calculation.
^* , And the deviation between the magnetizing current command i _d ^* and the detected magnetizing current value i _d is proportionally / integrally calculated to find the magnetizing voltage command V _d ^* in the rotating coordinate system. Give to.

Here, the detected torque current value i _q and the detected magnetizing current value i _d are obtained as follows.

First, the current transformers 35 and 36 detect the u-phase current i _u and the w-phase current i _w (both AC amounts) of the motor current, and the A / D converters 37 and 38 detect the analog amount to the digital amount. To the coordinate conversion unit 41. Further, the encoder 39 rotates together with the rotor of the electric motor 1 to generate a pulse signal P, and based on the pulse signal P, the position (phase) θ of the rotor of the electric motor 1 is detected by the position calculation unit 40, and coordinate conversion is performed. It is given to the parts 41 and 42.

The coordinate conversion unit 41 uses the u-phase current detection value i_uWhen
w-phase current detection value i_wRemaining v phase current i_v(Not shown)
Is calculated, and these three-phase current detection values i_u,
i_v, I _wTwo-phase current in the stationary coordinate system by three-phase to two-phase conversion
Converted to the detected value and considering the rotor phase angle θ
From the detected torque current i in the rotating coordinate system_qAnd magnetizing charge
Flow detection value i_dAsk for.

The coordinate conversion section 42 is a torque voltage command V _q ^* expressed in a rotating coordinate system given by the current control section 34 ^.
And the magnetizing voltage command V _d ^* is subjected to two-phase / three-phase conversion in consideration of the rotor phase angle θ, and the three-phase voltage commands Vu ^* , Vv ^* , Vw in the stationary coordinate system are calculated from V _q ^* and V _d ^{*. *} (Both AC amount) is obtained and given to the inverter 30.

In the inverter 30, the three-phase voltage command V
The PW conversion unit 31 performs pulse width modulation based on u ^* , Vv ^* , and Vw ^* , and controls the main circuit unit 32. As a result, the magnitude and phase of the electric motor current are determined by the torque current command i _q.
The magnitude and phase of the electric motor terminal voltage are controlled so that the values will correspond to ^* and the magnetizing current command i _d ^* .

The torque current command i _q ^* is generated by, for example, a speed control loop (not shown). The magnetizing current command i _d ^* is generated, for example, by the weakening magnetic flux calculator 43 based on the torque current command i _q ^* and the motor speed (electrical angular speed) ω using a predetermined algorithm.
The motor speed ω is calculated and detected by the speed calculator 44 based on the pulse signal P from the encoder 39.

[0014]

In the above-mentioned prior art, the control structure is complicated in the following points (1) and (2), and it is necessary to solve the problems. (1) The u-phase current i _u and the w-phase current i _w are used to detect the motor current separately by the coordinate conversion unit 41 into the torque axis component i _q and the magnetic flux axis component i _d. Two circuits of A / D converters 37 and 38 are required. Moreover,
Input i _u of these A-D converter 37 and 38, since i _w is an alternating current amount, requires expensive A-D converter of high speed operation. (2) Further, since the current adjustment is performed in parallel and independently for each of the torque axis component and the magnetization axis component, the current control unit 3
4 is required to operate at high speed.

An object of the present invention is to perform highly accurate torque control of a permanent magnet type electric motor with a simple control configuration.

[0016]

SUMMARY OF THE INVENTION A permanent magnet type motor control method of the present invention which solves the above problems is a permanent magnet for supplying a motor current from an inverter to a permanent magnet type motor and controlling the magnitude and phase of this motor current. Type electric motor control method, the magnitude of the electric motor current is detected, and the current detection value and the vector sum of the magnetizing current command of the magnetic flux axis component and the torque current command of the torque axis component orthogonal to the magnetic flux axis are calculated. The magnitude of the motor terminal voltage is adjusted so that the absolute value of the current command matches, the phase command of the motor terminal voltage is determined from the torque current command and the magnetizing current command, and the phase of the motor terminal voltage is controlled. It is characterized by:

Further, in the permanent magnet type motor control method of the present invention, the motor current supplied by the inverter is a square wave current having a conduction width of 120 °, and the magnitude of the motor current is detected by full-wave rectification. Or the phase command is determined from the torque current command and the magnetizing current command, and the motor speed.

On the other hand, the permanent magnet type motor control device of the present invention which solves the above problems supplies a square wave current of 120 ° conduction width to the permanent magnet type motor as a motor current from the square wave PWM type inverter, and this motor is driven. In a permanent magnet type motor control device that controls the magnitude and phase of a current based on a magnetizing current command of a magnetic flux axis component and a torque current command that is a torque axis component orthogonal to the magnetic flux axis, the magnitude of the motor current is a full wave. Current detection means for detecting by rectification, current command absolute value calculation means for calculating current command absolute value from vector sum of the torque current command and magnetizing current command, current detection value obtained by the current detection means and the above A current command that outputs a voltage command for adjusting the magnitude of the motor terminal voltage so that the current command absolute value obtained by the current command absolute value calculation means matches. Means, a speed detecting means for detecting the electric motor speed, a speed detected value obtained by the speed detecting means, the torque current command, and the magnetizing current command, to calculate a phase command of the motor terminal voltage. It is characterized by comprising a phase command calculation means and the square wave PWM inverter for controlling the magnitude and phase of the electric motor terminal voltage based on the voltage command and the phase command.

Further, in the permanent magnet type motor controller of the present invention, the current adjusting means calculates the absolute value of the current command and the detected current value, and the absolute value of the calculated value is used as the square wave PWM type. The square wave PWM modulator of the inverter is converted into an on-off duty command, and this duty is output as a voltage command, or a polarity monitoring means for monitoring the polarity change of the torque current command is provided, The current adjusting means outputs the voltage command by performing a proportional integral calculation on the deviation between the absolute value of the current command and the detected current value, and outputs the integrated value and the output value of the voltage command when the polarity of the torque current command changes. Is set to zero, or the PW is such that the operation cycle of the current adjusting means is a square wave.
It is characterized by being a positive integer multiple of the period of the M-modulated wave, or a phase compensation command for compensating the delay current phase of the current actually flowing in the permanent magnet type motor is added in advance to the phase command of the motor terminal voltage. It is characterized in that it is provided with an addition means, or is provided with a phase compensation command calculation means for calculating the phase compensation command as a function of the motor speed.

[0020]

In the present invention, the adjustment of the motor terminal voltage is divided into the magnitude adjustment and the phase adjustment, and the former uses the absolute value of the current command calculated by the vector sum of the magnetizing current command and the torque current command. The magnitude of the motor terminal voltage is adjusted so that the absolute value and the detected current value match, and the latter adjusts the phase of the motor terminal voltage by determining the phase command from the magnetizing current command and the torque current command. Therefore, since only one current adjusting system is required, the calculation is simpler than the conventional one, and the control configuration is simplified. Further, since the detected current value is the magnitude of the motor current and is not related to the number of phases, only one A-D converter is required for digitizing the current control system.

In particular, when a square wave current having a 120 ° conduction width is supplied as the motor current, the current detection value obtained by full-wave rectifying the motor current is the maximum value (peak value) of the three-phase current.
Since it is a DC signal ideally, there is an advantage that both the current control system and the AD converter can operate at low speed, and it is possible to easily realize digital control by a one-chip microcomputer or the like. Become.

Further, the phase command of the motor terminal voltage can be basically determined from the relational expressions of the magnetic flux axis voltage and the torque axis voltage and the magnetizing current and the torque current, but the phase of the actually flowing motor current is Since the current phase is later than that, it is necessary to compensate. Since this lag current phase changes depending on the motor speed, by preparing a phase compensation command as a function of the motor speed and determining the phase command from the magnetizing current command and the torque current command, and the motor speed, the control accuracy can be improved. Is improved.

Further, when the voltage command is the absolute value of the value obtained by the calculation of the current command absolute value and the current detection value, the voltage command value has no polarity, and the drive mode or the regenerative mode, which is the control mode of the motor, is eliminated. Only the magnitude of the current command is controlled regardless of the mode. Therefore, there is an advantage that the calculation of the current adjustment system is further simplified and a low speed operation is sufficient. Further, by using the ON / OFF duty command as the voltage command having no polarity, the voltage command to the inverter becomes much simpler than the conventional one.

Since the voltage command is determined on the basis of the absolute value of the current command as described above, for example, during the operation in the drive mode under the torque current command of a certain value, the regenerative torque current command of the same magnitude is suddenly changed. When the magnitude is the same and only the polarity of the torque current command changes, the voltage command does not change immediately, but only the phase command changes instantaneously by about 180 °. Therefore, the motor terminal voltage does not change immediately, but only the phase changes abruptly. In this state, an overcurrent may occur in the electric motor depending on the magnitude relationship between the induced voltage of the permanent magnet type electric motor and the inverter output voltage. This tendency is due to the cushion calculation process that gently suppresses the change in the torque current command. Great if not done.

As a countermeasure against this, in the present invention, the polarity change of the torque current command is monitored, and when the polarity is changed, the voltage command is set to zero, the inverter output voltage is once set to zero, and then the current adjusting operation is restarted. Further, when the voltage command is calculated by the proportional / integral calculation, not only the voltage command but also the integral value is set to zero to prevent the integral value from affecting the current adjusting operation after the restart.

Further, in the present invention, the number of pulse trains of the same duty in the square wave PWM modulation wave is always a constant value because the calculation cycle for calculating the voltage command is set to a positive integer multiple of the cycle of the square wave PWM modulation wave. (The positive integral multiple), and the operation of the voltage control system is stabilized.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings with reference to the accompanying drawings. In the drawings, FIG. 1 shows a configuration of a permanent magnet type motor control device according to an embodiment of the present invention. Also, FIG.
(A)-(d) shows the voltage-current vector of each operation mode in 4-quadrant operation. FIG. 3 shows a time chart of the gate signal during normal rotation driving. Reference numeral 1 in FIG. 1 denotes a three-phase permanent magnet electric motor (PM motor), which may be abbreviated as an electric motor in the following description.

As shown in FIG. 1, the permanent magnet type motor controller of the present embodiment mainly comprises a polar coordinate converter 2, a deviation calculator 3, a current detector 4, an AD converter 8, and a current converter. A regulator 9, a square wave PWM inverter 10, a polarity monitor 17, an adder 18, a phase compensation command calculator 19,
It is composed of a speed calculation unit 20 and an encoder 21, and the control is digitized as much as possible. In the drawings, reference numeral 16 is a DC power supply, 22 is a cushion calculation unit, 23 is a weak magnetic flux calculation unit, 24 is an operation mode determination unit, and 25 is a torque command calculation unit.

First, the inverter 10 will be described, and then the current detector 4 will be described.

The inverter 10 supplies a square wave current of 120 ° conduction width to the electric motor 1, and the electric motor terminal voltage is
The adjustment is performed so as to have the magnitude of the voltage command V ₁ ^* given from the current regulator 9 and the phase of the phase instruction θ _1V ^* given from the adder 18. Therefore, the inverter 1
0 is a carrier wave generator 11, a position counter converter 12,
Gate generator 13, PWM modulator 14, and main circuit 15
It consists of

The carrier wave generator 11 generates a square wave, changes the duty of the square wave according to the duty command given as the voltage command V ₁ ^* from the current regulator 9, and outputs it to the square wave PWM modulator 14.

The position counter converter 12 outputs the phase command θ _1V ^*
Is converted into a voltage phase amount CN (θ _1V ^* + Δθ _1V ^* ) representing a position counter amount (leading phase from the induced voltage phase) and given to the gate generation unit 13.

Based on the voltage phase amount CN, the position detection pulses P _U , P _V , P _W and the speed detection pulse P _S from the encoder 21, and the determination result 24A of the operation mode determination unit 24, the gate generation unit 13 permanently A gate firing phase signal 13 having a width of 120 ° in electrical angle as a phase signal advanced by the amount of the advanced phase from the induced voltage phase with reference to the detected phase of the magnet.
A is generated, and this signal 13A is supplied to the square wave PWM modulator 14
And to the main circuit 15.

Here, the encoder 21 rotates together with the rotor of the electric motor 1 to detect a position detection pulse P _{U having} a width of 120 ° corresponding to the U, V, and W phase magnet positions for representing the magnetic flux axis.
It outputs P _V and P _W and a speed detection pulse P _S having a frequency proportional to the motor speed. In addition, the operation mode determination unit 24
Is based on the gear information, the polarity of the torque current command i _q ^* , and the polarity of the electric motor speed (electrical angular velocity) ω, the driving mode in the normal rotation of the electric motor 1 in operation as shown in FIGS. It is determined whether the control is performed in the regenerative mode for reverse rotation, the regenerative mode for normal rotation, or the drive mode for reverse rotation, and the determination result 24A is output. The motor speed ω is calculated by the speed calculator 2
0 is an electrical angle given from the gate generator 13 and is calculated based on the pulse 13B having a cycle of 60 °.

In this embodiment, the square wave PWM modulator 14 controls the lower arm phase (X, Y,
(Z-phase) is input, and the square wave of each phase having a duty of the voltage command V ₁ ^* is PWM-modulated. As a result, 14
A is given to the main elements of the X, Y, and Z phases of the main circuit 15 as a main element gate signal.

In the main circuit 15, of the gate firing phase signal 13A from the gate generator 13, the upper arm phase (U, V,
(W phase) is directly input as the main element gate signal, and the main element gate signal 14A of the lower arm phase that has passed through the PWM modulator 14 is input to input the X, Y, Z, U, V, and W phases. The main element _fires, and a three-phase voltage corresponding to the voltage command V ₁ ^* and the phase command θ _1V ^* is applied to the electric motor 1. As an example, a time chart of the gate signal at the time of normal rotation driving is shown in FIG.

The current detection unit 4 is connected to the electric motor from the inverter 10.
Detecting the magnitude of the current (motor current) flowing through 1
And the u-phase current i due to the two converters 5 and 6_uAnd w phase
Current i_w(Both analog AC amounts) are detected and
Full-wave rectification by a three-phase full-wave rectification circuit 7 based on
An analog amount of current that indicates the maximum current value (zero peak value)
Detected value i_aGet. This current detection value i_aDigital control
In order to detect the digital amount of current by the AD converter 8,
Value i₁To the deviation calculation unit 3. In this case,
Since the motive current is a square wave current with a 120 ° conduction width,
The output of the wave rectifier circuit 7 is extremely close to direct current. Note that v-phase electric
The flow iv is the expression (i_u+ I _V+ I_w= 0)
Find more.

Next, the functions of other parts will be described in order.

The polar coordinate conversion unit 2 has two functions. The magnetizing current command i _d ^* and the torque current command i _q ^* are input, and first, the current command absolute value i ₁ ^* is calculated by a predetermined calculation. Secondly, the phase command θ _V ^* is calculated by a predetermined calculation. Needless to say, the magnetizing current command i _d ^* is a component parallel to the magnetic flux axis in the rotating coordinate system (dq coordinate system) with the magnetic flux axis as the reference, and the torque current command i _q ^* is orthogonal to the magnetic flux axis. It is a component (a component parallel to the torque axis).

The torque current command i _q ^* is given from a higher order such as a speed control system, but here, it is calculated by the torque command calculation unit 25 from the accelerator amount, the electric motor speed ω and the gear information. Further, since the torque current command i _q ^* generally changes in a step-like manner in many cases, in the present embodiment, the cushion calculation unit 22 suppresses the change to a smooth change before the polar coordinate conversion unit 2.
Is given to.

Further, regarding the magnetizing current command i _d ^* , in the present embodiment, the weak magnetic flux calculating section 23 causes the torque current command i _d ^*.
It is calculated from _q ^* and the motor speed ω, the details of which will be described later.

The current command absolute value i ₁ ^* is the magnetizing current command i
_{Since d} ^* and the torque current command i _q ^* are orthogonal, they are calculated as the absolute value of these vector sums | i _d ^* + i _q ^* |.

The phase command θ _V ^* indicates the phase of the motor terminal voltage when the motor current flows according to the magnetizing current command i _d ^* and the torque current command i _q ^*. From the magnetic flux axis voltage V _d given by 1) and the torque axis voltage V _q given by equation (2), equation (3)
It is calculated by the calculation of. R, L _d , L _q , ψ _a , ψ
_e is a motor constant of the electric motor 1.

[0044]

[Number 1] ^{_{V d = R · i d *}} -ωL q · i q * ... formula (1)

[Number 2] ^{_{V q = R · i q *}} + ωL d · i d * + ωψ a ... formula (2) However, ψ _a = √3 · ψ _e

(Equation 3)

In equations (1) and (2), R: armature resistance for one phase ω: motor speed (electrical angular velocity) L _d : flux axis armature self-inductance L _q : torque axis armature self-inductance ψ _e : Effective value of armature flux linkage by permanent magnet

However, the actual phase of the electric motor current is the phase command θ _V calculated by the equations (1) to (3).
^The current phase will be slightly delayed from ^* .

Therefore, in order to compensate the delay current phase, in the present embodiment, the adding unit 18 adds the phase compensation command Δθ _V ^* in advance to the phase command θ _V ^* , and as a result, θ _V ^* + Δθ _V ^* is the final value for the inverter 10. Phase command θ _1V ^* . The phase compensation command Δθ _V ^* is determined based on the knowledge that the lagging current phase depends on the motor speed ω, and is prepared in advance as a function of the motor speed ω in the form of a table or the like. Shall be decided.

The deviation calculator 3 obtains the deviation Δi ₁ ^* (= i ₁ ^* -i ₁ ) between the current command absolute value i ₁ ^* and the detected current value i _1, and supplies it to the current controller 9.

The current controller 9 has a calculation cycle which is a positive integer multiple of the cycle of the square wave used as the modulation wave, and is proportional to the deviation Δi ₁ ^*.
An integral (PI) operation is performed, and the absolute value of the calculated value is converted into an on / off duty and output as a voltage command V ₁ ^* for the inverter 10.

However, when the polarity monitor 17 detects a change in the polarity of the torque current command i _q ^* , the current controller 9 outputs the output value (voltage command (duty command) V ₁ ^* ) and the integrated value during the PI calculation. To zero.

In this embodiment, the polarity monitoring unit 17 inputs the output value of the cushion calculation unit 22 as the torque current command i _q ^* and monitors the presence or absence of a polarity change.

Next, the calculation of the magnetizing current command i _d ^* will be described.

As is well known, when a magnetizing current is passed through a permanent magnet type motor, there is a demagnetizing action due to a d-axis (flux axis) armature reaction in the same motor, and this action causes a gap magnetic flux between the stator and the rotor. Has the effect of reducing
By controlling the magnetizing current, an increase in the armature terminal voltage can be suppressed and the speed control range can be expanded. So-mentioned Expression (1), the magnetization current command i _d ^* as the motor terminal voltage is calculated ^{_{(V d 2 + V q 2}} ) 1/2 is within the possible output voltage of the inverter 10 from (2) decide. However, there are various methods depending on how to demagnetize.

[0054] For example, basically magnetized to the maximum torque is obtained current command with the minimum current at low speed i _d ^* and determining the magnetization current command i _d so as to suppress the motor terminal voltage within the limit range at high speed ^* Decide.

From the above equations (1) and (2), the armature reaction
Induced voltage V₀Is given by the following equation (4)
And Also, depending on the rating of the inverter 10, etc.
The upper limit of the flow is I_am, The upper limit of the output terminal voltage is V_amAnd
Then, the induced voltage V₀Upper limit V _{0 m}Is given by the following equation (5)
It As a result, the magnetizing current command i_d ^*And torque current command i
_q ^*The relationship between and is within the range shown in the following equations (6) and (7).
Subject to the restrictions. However, R, ω, ψ_a, L_a, L_dIs
As defined above, and ρ = L_q/ L_dAnd

[0056]

[Number 4] ^{_{V 0 2 = (ωL d ·}} i d * + ωψ a) 2 + (ωL q · i q *) 2 = ω 2 ((L d · i d * + ψ a) 2 + ((L q / L _d ) L _d · i _q ^* ) ² ) = ω ² ((L _d · i _d ^* + ψ _a ) ² + (ρL _d · i _q ^* ) ² ) ... Formula (4)

[Equation 5] V _0m = V _am −R · I _am (Equation 5)

## EQU6 ## (i _d ^* ) ² + (i _q ^* ) ² = I _am Equation (6)

[Equation 7] ^{_{(L d · i d * +}} ψ a) 2 + (ρL d · i q *) 2 = (V 0m / ω) 2 ... (7)

At a sufficiently low speed, the voltage-limiting ellipse of equation (7) is large, so that the magnetization is determined from the current-limiting circle of equation (6) and the maximum torque / minimum current curve determined by the relationship between copper loss and torque. The current command i _d ^* is determined by the following equation (8).
However, K ₁ = K _f / (2 (ρ−1)), K _f = ψ _a / L _d
Is.

[0058]

(Equation 8)

If the magnetizing current command i _d ^* determined by the equation (8) is used as it is at a high speed as well, the voltage limiting ellipse of the equation (7) becomes narrower as the speed ω increases, so that the induced voltage V ₀ exceeds the limiting range. Will end up. Then, using the magnetizing current command i _d ^* determined by the equation (8), the induced voltage V ₀ is calculated from the equation (9) which is a modification of the equation (4), and if V ₀ ≦ V _0m , it is used as it is. To do. If V ₀ > V _0m , the magnetizing current command i _d ^* is calculated by the following expression (10) derived from the expression (7) of the voltage limiting ellipse, and this is used instead. However, K _V
= V _0m (ωL _d ), i _q ^* ≦ K _V / P.

[0060]

[Equation 9]

[Equation 10]

Next, the operation of the entire control device will be described.

First, based on the torque current command i _q ^* input through the cushion calculator 22 and the magnetizing current command i _d ^* obtained by the weakening flux calculator 23, the polar coordinate converter 2 calculates the absolute current command value (i _q ^*). And the absolute value of the vector sum of i _d ^* ) i ₁ ^* and the phase command θ _V ^* of the motor terminal voltage are calculated.

Regarding the current command absolute value i ₁ ^* , A-D
The deviation Δi ₁ from the detected current value i ₁ by the three-phase full-wave rectification input through the converter 8 is calculated by the deviation calculation unit 3, and the current controller 9 proportionally integrates the cycle of the square wave modulated wave with a positive integer multiple. Calculation is performed, the absolute value of the calculated value is converted into a duty, and this is given to the inverter 10 as a voltage command V ₁ ^* . However, the polarity monitoring unit 17 causes the torque current command i _q
^When the polarity change of ^* is detected, the integrated value and the voltage command V ₁
^Set both ^* to zero. As a result, the voltage command V ₁ ^* gradually rises from zero after the polarity of the torque current command i _q ^* changes, at a time determined by the response characteristic of the current regulator 9. Therefore, the output voltage of the inverter 10 also gradually increases from zero.

For the phase command θ _V ^* , the phase compensation command Δθ _V ^* obtained as a function of the motor speed ω by the phase compensation command calculation unit 19 is added by the addition unit 18, and the result θ
_1v ^* is given to the inverter 10.

In the inverter 10, the magnitude of the motor terminal voltage is adjusted to a desired value by PWM-modulating the square wave with the voltage command V ₁ ^* (duty command), and the gate firing from the phase command θ _1v ^*. The phase of the motor terminal voltage is adjusted to the desired value by determining the phase.

As a result, a square wave current having a magnitude and phase corresponding to the magnetizing current command i _q ^* and the torque current command i _q ^* and having a 120 ° conduction width is supplied to the electric motor 1 as an equivalent three-phase current.

[0067]

According to the present invention, the adjustment of the motor terminal voltage is divided into the magnitude adjustment and the phase adjustment, and the former is given a current command calculated by the vector sum of the magnetizing current command and the torque current command. The magnitude of the motor terminal voltage is adjusted so that the absolute value and the detected current value match, and in the latter case, the phase command is determined from the magnetizing current command and the torque current command to adjust the phase of the motor terminal voltage. , The current regulation system is 1
Computation is easier than before and the control configuration is simplified. Further, since the detected current value is the magnitude of the motor current and is not related to the number of phases, only one A-D converter is required for digitizing the current control system.

In particular, when a square wave current having a 120 ° conduction width is supplied as the motor current, the current detection value obtained by full-wave rectifying the motor current is the maximum value (peak value) of the three-phase current.
Since it is a DC signal ideally, there is an advantage that both the current control system and the AD converter can operate at low speed, and it is possible to easily realize digital control by a one-chip microcomputer or the like. Become.

Further, the phase command of the motor terminal voltage is prepared as a function of the motor speed, and the phase compensation command is prepared.
By determining from the magnetizing current command and the torque current command and the motor speed, the control accuracy is improved.

Further, by setting the voltage command to the absolute value of the value obtained by the calculation of the current command absolute value and the current detection value,
Since the voltage command value has no polarity and only the magnitude of the current command is controlled regardless of the drive mode or regeneration mode, the calculation of the current adjustment system is further simplified, and
It has the advantage that it can be operated at low speed. Further, by using the ON / OFF duty command as the voltage command having no polarity, the voltage command to the inverter becomes much simpler than the conventional one.

Further, in the present invention, the polarity change of the torque current command is monitored, and when the polarity is changed, the voltage command is set to zero, the inverter output voltage is once set to zero, and the current adjusting operation is restarted. When calculating by integral calculation, not only the voltage command but also the integral value is set to zero.
It is possible to prevent overcurrent when the polarity of the torque current command changes.

Further, in the present invention, the number of pulse trains of the same duty in the square wave PWM modulation wave is always a constant value by setting the calculation cycle for calculating the voltage command to be a positive integer multiple of the cycle of the square wave PWM modulation wave. Therefore, the operation of the voltage control system is stabilized.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a permanent magnet type electric motor control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a voltage / current vector in each control mode of four-quadrant operation.

FIG. 3 is a diagram showing a time chart of a gate signal during normal rotation driving.

FIG. 4 is a diagram showing a conventional example.

[Explanation of symbols]

1 Permanent Magnet Motor 2 Polar Coordinate Converter 3 Deviation Calculator 4 Current Detector 5, 6 Current Transformer 7 Three-Phase Full-Wave Rectifier Circuit 8 AD Converter 9 Current Controller 10 Inverter 11 Carrier Wave Generator 12 Position Counter Conversion Part 13 Gate generation part 13A Gate firing phase signal 14 PWM modulation part 15 Main circuit 16 DC power supply 17 Polarity monitoring part 18 Addition part 19 Phase compensation command calculation part 20 Speed calculation part 21 Encoder 22 Cushion calculation part 23 Weak magnetic flux calculation part 24 Operation mode determination unit 25 Torque command calculation unit i _d ^* Magnetizing current command i _q ^* Torque current command i ₁ ^* Current command absolute value i ₁ Current detection value Δi ₁ ^* Deviation V ₁ ^* Voltage command θ _V ^* , θ _1V ^* Phase Command Δθ _V ^* Phase compensation command ω Motor speed

Claims (9)

[Claims] 1. A permanent magnet type motor control method for supplying a motor current from an inverter to a permanent magnet type electric motor to control the magnitude and phase of the electric motor current, wherein the magnitude of the electric motor current is detected. Adjust the magnitude of the motor terminal voltage so that the value matches the absolute value of the current command calculated by the vector sum of the magnetizing current command of the magnetic flux axis component and the torque current command of the torque axis component orthogonal to the magnetic flux axis. A phase command of the motor terminal voltage is determined from the torque current command and the magnetizing current command, and the phase of the motor terminal voltage is controlled. 2. The permanent magnet according to claim 1, wherein the motor current supplied by the inverter is a square wave current having a 120 ° conduction width, and the magnitude of the motor current is detected by full-wave rectification. Magnet type motor control method. 3. The permanent magnet type motor control method according to claim 1, wherein the phase command is determined from the torque current command, the magnetizing current command, and the motor speed. 4. A square-wave PWM type inverter supplies a square-wave current of 120 ° conduction width to the permanent magnet type motor as a motor current, and the magnitude and phase of this motor current are the magnetizing current command and the flux axis of the magnetic flux axis component. In a permanent magnet type motor control device that controls based on a torque current command that is a torque axis component that is orthogonal to, a current detection unit that detects the magnitude of the motor current by full-wave rectification, the torque current command and the magnetizing current. The current command absolute value calculation means for calculating the current command absolute value from the vector sum of the command, the current detection value obtained by the current detection means and the current command absolute value obtained by the current command absolute value calculation means Current adjusting means for outputting a voltage command for adjusting the magnitude of the motor terminal voltage so as to match, speed detecting means for detecting the motor speed, and this speed detecting means. Based on the speed detection value obtained by the means, the torque current command, and the magnetizing current command, the phase command calculation means for calculating the phase command of the motor terminal voltage, based on the voltage command and the phase command And a square-wave PWM inverter for controlling the magnitude and phase of the electric motor terminal voltage, and a permanent magnet type electric motor control device. 5. The current adjusting means calculates the absolute value of the current command and the detected current value, and the absolute value of the calculated value is turned on / off of a square wave PWM modulator of the square wave PWM inverter. 5. The permanent magnet type electric motor control device according to claim 4, wherein the duty command is converted into the duty command and the duty is output as a voltage command. 6. A polarity monitoring means for monitoring a polarity change of the torque current command is provided, and the current adjusting means performs a proportional integral calculation on a deviation between an absolute value of the current command and a detected current value to output the voltage command. The permanent magnet type electric motor control device according to claim 5, wherein the integrated value and the output value of the voltage command are set to zero at the time when the polarity of the torque current command changes. 7. The permanent magnet type electric motor control device according to claim 4, wherein the operation cycle of the current adjusting means is a positive integer multiple of the cycle of the PWM modulated wave which is a square wave. 8. An addition means for adding in advance a phase compensation command for compensating for the delay current phase of the current actually flowing in the permanent magnet type motor to the phase command of the motor terminal voltage. Alternatively, the permanent magnet type electric motor control device according to 5 or 6 or 7. 9. The permanent magnet type motor controller according to claim 8, further comprising phase compensation command calculation means for calculating the phase compensation command as a function of the motor speed.