JP3080813B2 - Motor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for controlling torque or speed of a motor by vector control.

[0002]

2. Description of the Related Art Conventionally, for controlling torque or speed of an AC motor, a vector for detecting an electric angle of a motor and independently controlling a torque current component and an exciting current component based on the detected electric angle. Controlled inverters are often used.

FIG. 6 is a block diagram showing a circuit of a conventional inverter 80. In the inverter 80 of FIG. 6, the electric angular velocity fn of the motor M is detected by the encoder RE, and the command angular velocity f1 obtained by adding the slip angular velocity fs to the electric angular velocity fn.
Based on *, the sine wave signals shifted from each other by 120 ° are output from the oscillator 85. This sine wave signal and the motor M
The excitation current Id and the torque current Iq are separated and detected by the current component calculation circuit (3 / 2-phase conversion circuit) 83 based on the phase current I.

The current control circuits 86 and 87 operate according to the deviations ΔId and ΔIq between the detected currents Id and Iq and the respective command values Id * and Iq *, and the command values Vd of the respective voltage components are obtained. *, Vq * are obtained. Based on these command values Vd * and Vq *, a voltage command calculation circuit (2 /
A three-phase conversion circuit) 84 calculates a command value v1 * of the voltage of each phase, a voltage proportional to the calculated command value v1 * is output from the power converter 81, and the driving of the motor M is controlled.

Conventionally, the circuit of the inverter 80 is as follows:
An analog circuit using an operational amplifier, or a combination of logic elements or a high-speed DS called software servo
A digital circuit using a P (digital signal processor) or the like, and a hybrid circuit thereof (Japanese Patent Application Laid-Open Nos. 64-23792 and 57).
-199489).

[0006]

However, in consideration of the performance, such as the calculation accuracy and the calculation speed, and the cost, the main circuit of the inverter may be constituted by a digital circuit using hard wires. Conceivable.

In such a case, the current control circuits 86 and 87
Is a proportional operator for multiplying the input deviation values ΔId and ΔIq by a proportional gain, an integral operator for performing an integrating operation, and output data of the proportional operator and output data of the integral operator. It is composed of an adder to be added, an output limiter for limiting output data of the adder, and the like,
A PI operation (proportional integration operation) is performed on the deviation value to calculate and output a control voltage (output data) that makes the deviation value zero.

In the current control circuit having such a configuration, when the output data of the adder is limited by the output limiter, that is, when the output of the circuit is saturated, the operation of the proportional operation unit and the integration operation unit is performed. Will be repeated even though is invalid.
In particular, in the integration calculator, when the output becomes saturated, not only the original control operation cannot be performed, but also the deviation value is accumulated as an error with the passage of time.
Then, when the target value changes next time,
The error accumulated from before becomes the initial offset of the integration calculator, so that the saturated state cannot be easily eliminated, and it takes time to follow the target value and the responsiveness is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a motor control device capable of improving the following performance and obtaining good responsiveness even when the output is saturated. I do.

[0010]

According to a first aspect of the present invention, there is provided an apparatus for detecting a phase current flowing through a motor, comprising: a current detector for detecting a phase current flowing through the motor; A 3 / 2-phase converter for obtaining a current, a current controller for obtaining a vector voltage command value based on a deviation value between the obtained vector component current and the vector current command value,
A motor control device comprising: a 2 / 3-phase converter for obtaining a phase voltage command value based on the vector voltage command value; and an inverter unit for supplying power to the motor based on the phase voltage command value. A unit that uses the deviation value as input data, multiplies the input data by a proportional gain, an integral operator that performs an integration operation on the input data, and an output of the proportional operator. An adder for adding data to the output data of the integration calculator; an output limiter for limiting the output data of the adder; and a saturation detection for detecting an amount of data limited by the output limiter And a subtracter for subtracting output data of the saturation detector from output data of the integration calculator.
Has a register inside, and outputs data of the subtractor.
The data is stored in the register, and the output data of the integrator is output.
Data is stored in the register and the value corresponding to the input data.
It is obtained by adding the stored data.

According to another aspect of the present invention, the register length of the register of the integral operation unit is multiplied by the proportional operation unit .
It is configured to be longer than the register length of the register used in the device . According to a third aspect of the present invention, the current detector is provided with a multiplier for multiplying the phase current converted into a digital value by a correction coefficient.

[0012] In the apparatus according to the fourth aspect of the present invention, the phase detector, which is converted into a digital value, is provided to the current detector.
An intermediate value filter is provided for extracting an intermediate value as data from a plurality of sampling data.

[0013]

In the current control section, when the output data of the adder becomes saturated and is limited by the output limiter, the saturation is detected and subtracted from the data in the integration calculator. This prevents errors from accumulating in the integration calculator during saturation.

When the register length of the register of the integral operation unit is made longer than the register length of the register of the proportional operation unit, the integral operation is performed with high accuracy despite the small register length as a whole, resulting in insufficient accuracy. Never be.
When an intermediate value filter is provided, so-called beard noise is effectively removed.

[0015]

FIG. 1 is a block diagram showing a circuit of an inverter 1 according to the present invention. The motor M used here is a three-phase induction motor, but can be applied to a synchronous motor by setting the slip angular velocity θs to zero.

The motor M has a magnetic pole position detection signal φu, which corresponds to the angular position (magnetic pole position or magnetic flux position) of the rotor shaft.
A plurality of magnetic pole position detectors MP that output φv and φw, and a pulse signal S1 (A phase, B
Phase, Z-phase).

The inverter 1 includes an inverter unit 11, an AD
Converter 12, 3/2 phase converter 13, 2/3 phase converter 1
4, current control unit 15, electric angle detection unit 16, magnetic pole position detection unit 17, trigonometric function generation unit 18, and current command setting unit 19
It is composed of

The inverter unit 11 includes a thyristor or an MO
It comprises a switching circuit or the like in which switching elements such as SFETs are connected in a three-phase bridge form, converts DC power into AC power and supplies the AC power to the motor M. Control the currents of phases U, V, W.

The A / D converter 12 converts the currents Iu and Iv of the respective phases U and V detected by the current transformer into digital values, corrects the converted values by multiplying them by coefficients, and performs correction. Performs filtering to remove noise. Details will be described later.

Based on the phase currents Iu and Iv from the AD converter 12, the 3/2 phase converter 13 outputs a d-axis current component (excitation current component) Id and a q-axis current component (torque current component) Id.
q is calculated by calculation. In calculating the d-axis current component Id and the q-axis current component Iq, a trigonometric function from the trigonometric function generator 18 is referred to. Further, the calculation requires the phase current Iw, which is obtained from the other phase currents Iu and Iv as Iw = − (Iu + Iv).

The 2/3 phase converter 14 includes a d-axis voltage command Vdc and a q-axis voltage command Vq output from the current controller 15.
c, voltage commands Vuc, Vv of each phase U, V, W
c and Vwc are calculated by calculation. Note that the calculation refers to the trigonometric function from the trigonometric function generator 18.

The current control unit 15 receives the d-axis current command Idc and the q-axis current command Iq input from the current command setting unit 19.
Based on c and the d-axis current component Id and the q-axis current component Iq from the 3/2 phase converter 13, a d-axis voltage command Vdc and a q-axis voltage command Vqc for making these deviations zero are output. I do.

The electrical angle detector 16 detects the electrical angle θE based on the pulse signal S1 output from the encoder RE and the magnetic pole position detection signals φu, φv, φw of the magnetic pole position detector. The electrical angle detector 16 counts the pulse signal S1, monitors the electrical angle θpn based on the count value in an electrical angle range θR detected by the magnetic pole position detection signals φu, φv, φw, and determines whether the electrical angle θpn is electrical. Angle range θR
If the electrical angle θpn is within the electrical angle range θR, the electrical angle θpn is output as the electrical angle θE. The corrected electrical angle after the correction is output as the electrical angle θE.

The magnetic pole position detecting section 17 includes an electric angle detecting section 16.
The electric angle θ is obtained by correcting the electric angle θE output from the control unit 101 with the slip angular velocity θs. The electrical angle θ is given by the following equation (1).

Θ = (θs + s · θE) / s (1) where s is a Laplace operator. The trigonometric function generator 18 generates a sin corresponding to the electrical angle θ.
It outputs the values of (θ) and cos (θ), receives the electrical angle θ, and outputs a trigonometric function value by a Taylor expansion series operation. The coefficients A1, A2,... Required for the development are stored in the memory.

The current command setting section 19 receives the torque command τ and converts it into a d-axis current command Idc and a q-axis current command Iqc.
Output as Except for the inverter section 11, the inverter 1 is constituted by a digital circuit formed into an LSI by hard wires.

FIG. 2 is a block diagram showing a part of the circuit of the current control unit 15 of the inverter 1. The current control unit 15
The deviation values ΔId and ΔIq of the input d-axis current component Id and torque current component Iq and the d-axis current command Idc and the q-axis current command Iqc are obtained, and a proportional integral operation is performed on each of the deviation values ΔId and ΔIq. Then, a d-axis voltage command Vdc and a q-axis voltage command Vqc that make the deviation value zero are calculated and output as output data. These are expressed by the following equations (2) and (3).

Vdc = GPd · ΔId + Σ (GId · ΔId) (2) Vqc = GPq · ΔIq + Σ (GIq · ΔIq) (3) In FIG. 2, only the arithmetic circuit for the d-axis component is shown. The operation circuit for the q-axis component is the same as that described above, and is omitted.

In FIG. 2, the arithmetic circuit for the d-axis component of the current controller 15 includes a deviation detector 31, a multiplier 32, a proportional gain register 33, a limiter 34, a multiplier 35, an integral gain register 36, and an integrator 37. , Limiter 38, adder 39, output limiter 40, saturation detector 41 and the like.

The deviation detector 31 obtains these deviation values ΔId by subtracting the d-axis current component Id from the d-axis current command Idc. The multiplier 32 multiplies the deviation value ΔId by a proportional gain GPd stored in the proportional gain register 33 by a fixed-point operation, and the result (GPd · ΔId)
Is output.

The limiter 34 limits the absolute value of the output of the multiplier 32 to a constant value when the output of the multiplier 32 exceeds a certain value in each of the positive and negative directions. For example, if the register of the multiplier 32 is 16 bits, the output is limited to 16 bits even if the multiplication result is larger.

The multiplier 35 multiplies the deviation value ΔId by the integral gain GId stored in the integral gain register 36 by a fixed-point operation, and calculates the result (GId · ΔId).
d) is output.

The integrator 37 integrates the output of the multiplier 35. That is, the input value is stored in the integration register 5 every predetermined period.
2, the integrated value is temporarily stored in the latch 53, and is added to the input value. This gives Σ (G
Id · ΔId) is obtained.

The integrating register 52 and the latch 53 are
A register (for example, a double-precision register) having a greater number of significant digits than the register used for the multiplier 32 of the proportional operation is used. This prevents waste such as insufficient precision or excessive precision in the calculation or the proportional calculation. Further, the influence of the delay due to the integration operation is prevented from being increased by the discrete processing.

The limiter 38 is, like the limiter 34,
When the output of the integrator 37 exceeds a certain value, the absolute value is limited to a certain value and limited. The adder 39 is for adding the output of the limiter 34 and the output of the limiter 38, whereby the result of the proportional operation (G
The sum SUM of Pd · ΔId) and the integration operation result Σ (GId · ΔId) is obtained.

The output limiter 40 is for limiting the absolute value of the output of the adder 39 to a constant value when the output of the adder 39 exceeds a certain value, similarly to the limiter 34 and the like. The output of the output limiter 40 is the d-axis voltage command Vdc
Is output as Incidentally, since the input to the output limiter 40 is one in which the outputs of the limiter 38 of the limiter 34 is added, even if the limiter 34 or 38 data is not restricted, the restriction by the output limiter 40 May receive it.

The saturated component detector 41 detects the component limited by the output limiter 40 (saturated component).
Input data SUM and output data Vd of output limiter 40
The difference DSA from c (= SUM−Vdc) is obtained as a saturation, and this is given as a subtraction input to the subtractor 42.

In the integrator 37, when performing the integrating operation, the subtracter 42 subtracts the saturated amount DSA. Therefore, when the output becomes saturated in the adder 39 and the output is limited by the output limiter 40, the saturation DSA is subtracted from the integration operation in the integrator 37, and the accumulation of errors in the integration register 52 is prevented. Is done.

As a result, a decrease in responsiveness due to accumulation of errors at the time of saturation can be prevented, and when the target value changes next time, the target value can be followed in a short time.

FIG. 5 is a diagram showing how the q-axis current component Iq responds to a change in the q-axis current command Iqc. Among these figures, FIG. 5A shows the case where the subtraction process of the saturated component DSA is performed, and FIG. 5B shows the case where the subtraction process is not performed.

In these figures, the q-axis current command (target value) Iqc is given in a sine wave shape so as to be saturated at a constant cycle. In the saturated state, FIG.
Although there is no difference in (b), it is understood that the followability to the target value is greatly improved by performing the subtraction processing of the saturation DSA after the point A where the saturation is no longer applied.

FIG. 3 is a block diagram showing a circuit of the AD converter 12. The AD conversion unit 12 outputs the current I of each phase U and V
AD converters 61a for converting u and Iv into digital values,
61b, multipliers 62a and 62b for multiplying the digital value by the correction coefficient KI stored in the coefficient register 63, and an intermediate value filter 64.

The multipliers 62a and 62b eliminate irregularities in data due to different detection values according to the type of current transformer used, and provide the phase current I / D output from the AD converter 12.
This is for making the full scale values of the data u and Iv uniform. Therefore, the correction coefficient KI is determined by the phase current I
The number of turns of the current transformer for detecting u and Iv, the sensitivity of the Hall element used in the current transformer, and the AD converter 61a,
The value is determined according to the number of bits of the bit 61b, etc., and is set by being input from an input device (not shown). by this,
In the subsequent arithmetic processing, the range width can be unified, the gain setting and tuning can be simplified, and the circuit of the inverter 1 can be standardized to have versatility.

The intermediate value filter 64 is for removing narrow pulse noise (so-called beard noise, see FIG. 4) contained in the data of the detected phase currents Iu and Iv. The intermediate value filter 64 includes the multipliers 62a and 62
The data output from b is sampled at a high speed to accumulate the data, and the past three sampling data are compared with each other, and only an intermediate value of the three data is adopted as each data. Thereby, the data of the maximum value or the minimum value affected by the beard noise or the like is excluded, and as a result, the beard noise is removed.

In general, whisker noise is mixed in from, for example, a switching power supply. Such a special noise cannot be removed without using a considerable number of samples and a calculation order in the case of a normal filter. But,
According to the intermediate value filter 64 of the present embodiment, harmful whisker noise can be effectively removed by a hardware circuit having a relatively small circuit size.

In the above-described embodiment, the circuit for the proportional operation or the integral operation in the current control unit 15 and the circuit for detecting the saturation DSA can be variously modified in addition to the above. In the intermediate value filter 64,
Although the intermediate value of the sampling data every three times in the past is adopted, the intermediate value or the average value of the intermediate data may be adopted from the sampling data of four or more times. In addition, the configuration of each part or the whole of the inverter 1, the processing content, the order, and the like can be variously changed in accordance with the gist of the present invention.

[0047]

According to the present invention, even when the output is saturated, the following ability is improved and good responsiveness can be obtained.

According to the second aspect of the present invention, there is no waste such as insufficient precision or excessive precision in the integral operation or the proportional operation with a small register length as a whole. According to the third aspect of the invention, the range width can be unified in the subsequent arithmetic processing, the gain setting and tuning can be simplified, and the circuit can be standardized to have versatility.

According to the fourth aspect of the present invention, harmful beard noise can be effectively removed by a hardware circuit having a relatively small circuit scale.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit of an inverter according to the present invention.

FIG. 2 is a block diagram showing a part of a circuit of a current control unit.

FIG. 3 is a block diagram illustrating a circuit of an AD conversion unit.

FIG. 4 is a diagram illustrating an example of a beard noise mixed in a phase current.

FIG. 5 is a diagram showing a response of a q-axis current component Iq to a change in a q-axis current command Iqc.

FIG. 6 is a block diagram showing a circuit of a conventional inverter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inverter (motor control apparatus) 11 Inverter part 12 AD conversion part (current detector) 13 3/2 phase conversion part 14 2/3 phase conversion part 15 Current control part 32 Multiplier (proportional calculator) 35 Multiplier (integration) Arithmetic unit) 37 integrator (integral arithmetic unit) 39 adder 40 output limiter 41 saturation detector 42 subtractor 62a, 62b multiplier 64 intermediate value filter M motor

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiharu Nishida 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel, Ltd. Kobe Research Institute (72) Inventor Nobuyuki Odera Nishi-ku, Kobe-shi, Hyogo 1-5-5 Takatsukadai Kobe Steel, Ltd.Kobe Research Institute (72) Inventor Atsuo Tachikawa 1-3-18 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo Kobe Steel Ltd. Inventor Tohru Takahashi 1-3-18, Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo Kobe Steel, Ltd.Kobe Head Office (72) Inventor Yuzo Takamon 150 Motoyashiki, Sanyacho, Toyohashi-shi, Aichi Prefecture Inside the factory (72) Inventor Kenji Inoue 100 Takegahana-cho, Ise City, Mie Prefecture Inside the Shinko Electric Co., Ltd. Ise Works (56) References JP-A-1-315295 ( P, A) (58) investigated the field (Int.Cl. ^7, DB name) H02P 5/408

Claims (4)

(57) [Claims] 1. A current detector for detecting a phase current flowing in a motor, a 3 / 2-phase converter for obtaining a vector component current based on the detected phase current, a vector component current obtained and a vector current command value A current control unit that obtains a vector voltage command value based on a deviation value from the current value; a 2/3 phase conversion unit that obtains a phase voltage command value based on the vector voltage command value
A motor control device having an inverter unit that supplies power to the motor based on the phase voltage command value, wherein the current control unit uses the deviation value as input data and multiplies the input data by a proportional gain Arithmetic unit for performing an integration operation on the input data, an adder for adding output data of the proportional arithmetic unit and output data of the integration arithmetic unit, and an output of the adder an output limiter for limiting the data, and saturated component detector for detecting the amount of data that is limited by the output limiter, the output <br/> of saturates the detector the integral calculator output data A subtractor for subtracting the data from the data , wherein the integration calculator has a register therein,
The output data of the arithmetic unit is stored in the register,
The output data of the arithmetic unit is a value corresponding to the input data and
By adding the data stored in the register
A motor control device characterized by what is required . 2. The motor control device according to claim 1, wherein the register length of the register of the integral arithmetic unit is longer than the register length of the register used for the multiplier of the proportional arithmetic unit. 3. The motor control device according to claim 1, wherein the current detector is provided with a multiplier for multiplying the phase current converted into a digital value by a correction coefficient. 4. The current detector is provided with an intermediate value filter for extracting, as data, an intermediate value of a plurality of sampling data of the phase current converted into a digital value. The motor control device according to claim 1, wherein