JP2008141824A - Synchronous motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve control reliability and control accuracy by making it possible to simply calculate a d-axis current command value Id<SP>*</SP>close to a theoretical value in a synchronous motor controller. <P>SOLUTION: As a current command value converter, which calculates a q-axis current command value Iq<SP>*</SP>and a d-axis current command value Id<SP>*</SP>from a torque command value T<SP>*</SP>, it is configured to calculate the q-axis current command value Iq<SP>*</SP>by multiplying the torque command value T<SP>*</SP>by a proportional constant K<SB>TI</SB>, compare this with a reference q-axis current value Iq<SB>base</SB>, calculate the d-axis current value Id<SP>*</SP>as a first linear function of the q-axis current command value Iq<SP>*</SP>, when the q-axis current command value Iq<SP>*</SP>is equal to or lower than the reference q-axis current value Iq<SB>base</SB>. When the q-axis current command value Iq<SP>*</SP>exceeds the reference q-axis current value Iq<SB>base</SB>as a result of the comparison, the converter calculates the d-axis current command value Id<SP>*</SP>as a second linear function of the q-axis current command value Iq<SP>*</SP>. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a synchronous motor control device, and more particularly to a technique for controlling an input current of a synchronous motor.

As conventional techniques related to the present invention, for example, Japanese Patent Application Laid-Open No. 2000-9284 (Patent Document 1), Japanese Patent Application Laid-Open No. 2000-358400 (Patent Document 2) and Japanese Patent Application Laid-Open No. 10-191700 (Patent Document 3). There is what is described in. Japanese Patent Laid-Open No. 2000-92984 discloses a control device that controls the current phase angle of a servo motor to a constant value other than 0 °, and takes into account reluctance torque and has high accuracy constant torque and constant output drive characteristics. In the DC brushless motor drive having the reverse saliency, the motor primary current is controlled so that the phase angle viewed from the torque current Iq becomes a constant value, and the fluctuation of the q-axis inductance Lq is compensated, describes a technique to calculate a torque current command value Iq ^* and the excitation current command value Id ^* to have a good constant torque and constant output drive characteristics precision, base speed of the excitation current command value Id ^* motor omega _b The two control ranges are determined separately. Japanese Patent Laid-Open No. 2000-358400 discloses a method of calculating the q-axis current command value Iq ^* and the d-axis current command value Id ^* according to the magnitude relationship between the input torque command value Tq ^* and the predetermined value Tref. When the torque command value Tq ^* is smaller than the predetermined value Tref, the q-axis current command value Iq ^* is calculated by Iq ^* = Kq1 × Tq ^* (Kq1 is a coefficient), and the d-axis current command value Id ^* Is calculated as Id ^* = 0, and when the torque command value Tq ^* is larger than the predetermined value Tref, Iq ^* = Kq1 × Tref is calculated, and the d-axis current command value Id ^* is calculated as Id ^* = Kd1 × computed by (Tq ^* -Tref) (Kd1 coefficient) that is to linearize the relationship between the output torque and the torque command value, always technique wherein was to allow the torque control with high precision In JP-A-10-191700, in a three-phase synchronous motor having a permanent magnet in a rotor, a high-speed response in a low-speed rotation region is satisfied without impairing characteristics that can widen a constant output range, and an output is provided. In order to provide a control method for preventing a decrease in torque, the d-axis current command value Id ^* and the q-axis current command Iq ^* are set based on the torque command T ^* and the speed feedback signal N _fb, and the operation mode switching signal is A technique is described in which the q-axis current command Iq ^* is switched to K1Iq ^* (K1 ≧ 1) and the d-axis current command Id ^* is switched to a constant value when given.

Japanese Patent Laid-Open No. 2000-92984 JP 2000-358400 A JP 10-191700 A

For example, in the above Japanese Patent Laid-Open No. 2000-92984, the excitation current command value (d-axis current command value) Id ^* is calculated by the following equation 1 when β is the constant current phase angle.
Id ^* = tan ⁻¹ β × Iq ^* (Equation 1)
The current phase angle β for generating the maximum torque with the same current is given by the following equation 2 by differentiating the torque equation with β. Here, Ф is a flux linkage by a permanent magnet, Lq is a q-axis inductance, Ld is a d-axis inductance, and Ia ^* is a current command execution value.
β = sin ^{-1 [[-Фa + {Фa 2 +8 (Lq} -Ld) Ia * 2} ] / 4 (Lq-Ld) Ia *] ... ( Equation 2)
As shown in Equation 2 above, β varies with Ia ^* . In the above Japanese Patent Laid-Open No. 2000-92984, the excitation current command value Id ^* is calculated with β being the angle at which the motor has the maximum efficiency at the current value Ia ^* . Thus, Id ^* calculation methods using various approximations are conceivable. However, recently, it is common to use a microcomputer for calculation, and the results obtained differ depending on the calculation capability of the microcomputer. For this reason, it is necessary to consider the capability of the microcomputer.

The problem of the present invention is that in the synchronous motor control device in view of the state of the prior art,
It is to make it possible to calculate the d-axis current command value Id ^* close to the theoretical value more easily than in the past, and to improve the control reliability and control accuracy.

In order to solve the above problems, the synchronous motor control device of the present invention is a current command value converter that calculates a q-axis current command value Iq ^* and a d-axis current command value Id ^* based on a torque command value T ^*. , is multiplied by a proportionality constant K _TI to the torque command value T ^* is calculated the q-axis current command value Iq ^*, which is compared with a reference of the q-axis current value Iq _base, the q-axis current command value Iq ^* is If the reference q-axis current value Iq _base or less, the d-axis current command value Id ^* is calculated as a first linear function of the q-axis current command value Iq ^* . If the axis current command value Iq ^* exceeds the q-axis current value Iq _base of the reference, a configuration that calculates the d-axis current command value Id ^* as the second primary function of the q-axis current command value Iq ^* Shall be. The first primary function is one obtained by multiplying the proportional constant a ₁ on the q-axis current command value Iq ^*, the second primary function, the q-axis current command value Iq ^* to the proportionality constant a ₂ And a constant b is added. With this configuration, the synchronous motor is caused to output a maximum torque close to the theoretical value at the same current value.

Further, as the current command value converter multiplies the proportional constant K _TI to the torque command value T ^* is calculated the q-axis current command value Iq ^*, which is compared with a reference of the q-axis current value Iq _base, As a result of the comparison, when the q-axis current command value Iq ^* is less than or equal to the reference q-axis current value Iq _base , the first d-axis current command value Id ^* _{1 is set} to the _first q-axis current command value Iq ^* . On the other hand, when the q-axis current command value Iq ^* exceeds the reference q-axis current value Iq _base , the second d-axis current command value Id ^* ₂ is calculated as the q-axis current command value Iq ^*. Is calculated from the DC voltage Vdc that is AC-converted, and a reference electrical angular velocity ω _base is calculated and compared with the electrical angular velocity ω of the synchronous motor. D-axis current command increase value Id proportional to the electrical angular velocity ω when the electrical angular velocity ω _base or more _ω is calculated, the d-axis current command increase value Id _ω is added to the first d-axis current command value Id ^* ₁ or the second d-axis current command value Id ^* ₂ , and the addition result is d The shaft current command value Id ^* is output. With this configuration, the synchronous motor is rotated at a high speed with a maximum torque or a torque close to the maximum torque under heavy load, and a stable torque is output even when voltage saturation occurs.

  ADVANTAGE OF THE INVENTION According to this invention, the synchronous motor control apparatus which can drive a synchronous motor with the stable high torque can be provided.

Embodiments of the present invention will be described below with reference to the drawings.
1 to 3 are explanatory views of a first embodiment of the synchronous motor control device of the present invention. 1 is a configuration example diagram of a synchronous motor control device as a first embodiment, FIG. 2 is a configuration example diagram of a current command value converter constituting the synchronous motor control device of FIG. 1, and FIG. It is explanatory drawing of the relationship between the q-axis current command value Iq ^* and the d-axis current command value Id ^{* in} the synchronous motor control apparatus.

In FIG. 1, 1 is a synchronous motor control device, 100 is a synchronous motor, 11 is an encoder as a position detector that detects the rotational position of a rotor (not shown) of the synchronous motor 100, and 12 is an output of the encoder 11. A speed calculator 13 for calculating the rotational speed of the rotor, a torque command value T from the current rotational speed N of the rotor obtained from the speed calculator 12 and a preset speed command value N ^{*. *} the calculated signal corresponding to the torque command value T ^* (for convenience, referred to the torque command value T ^*) the speed control calculator which outputs a, 14, based on the torque command value T ^*, q-axis current command value Iq ^* And the d-axis current command value Id ^* are calculated and signals corresponding to the q-axis current command value Iq ^* and the d-axis current command value Id ^* (for convenience, the q-axis current command value Iq ^* and the d-axis current command value current command value converter d ^* hereinafter) formed by the output, 15, synchronous current detector for detecting the input current value of the motor 100, 16, an input current value the detected q-axis current value Iq and d A UVW / dq converter, 17a serving as an axial current value converter for converting into an axial current value Id, is a q-axis current command value Iq ^* output from the current command value converter 14; In addition to the q-axis current value Iq output from the UVV / dq converter 16 and adding the q-axis current value Iq to the q-axis current command value Iq ^*, an adder 17b The d-axis current command value Id ^* output from the command value converter 14 and the d-axis current value Id output from the UVW / dq converter 16 are added to the d-axis current command value Id. An adder 17c for subtracting the d-axis current value Id from ^* A signal corresponding to the speed command value N ^* of the rotor of the electric motor 100 (for convenience, the speed command value N ^* ) and a signal corresponding to the current speed N of the rotor output from the speed calculator 12 (for convenience, the current speed) N), and an addition unit 18 that subtracts the current speed N from the speed command value N ^* and outputs speed deviation information, and 18 adds the q-axis current value Iq from the q-axis current command value Iq ^*. Based on the subtracted current value deviation information and the current value deviation information obtained by subtracting the d-axis current value Id from the d-axis current command value Id ^*, a current control calculation for calculating and outputting the input current value of the synchronous motor 100 It is a vessel. The controlled input current output from the current control arithmetic unit 18 is input to a stator coil (not shown) of the synchronous motor 100, and the synchronous motor 100 is driven. The speed control calculator 13 forms and outputs the torque command value T ^* based on the speed deviation information output from the adder 17c. The current detector 15 and the UVW / dq converter 16 form a feedback control system for the current control calculator 18.

In the configuration of FIG. 1, the current value detected from the three-phase current detector 15 is input to the UVV / dq converter 16. The W-phase current may be detected, and the V-phase current Iv may be calculated as Iv = Iu−Iw with the difference between the U-phase current Iu and the W-phase current Iw.
1 used in the following description are given the same reference numerals as in FIG.

FIG. 2 is a configuration example diagram of the current command value converter 14 constituting the synchronous motor control device 1 of FIG.
2, 141, by multiplying the proportionality constant _{K TI} to the torque command value ^{T *} q-axis current command value calculator that calculates and outputs the q-axis current command value Iq ^*, 142 was the output q The comparison unit 143 compares the level of the axis current command value Iq ^{* with} the level of the reference q-axis current value Iq _base. As a result of the comparison by the comparison unit 142, the level of the q-axis current command value Iq ^* is A first linear function calculator that calculates the d-axis current command value Id ^* as a first linear function of the q-axis current command value Iq ^* when the level is equal to or lower than the reference q-axis current value Iq _base . , 143a are proportional constant setting unit for setting a proportional constants _{a 1} multiplied to the q-axis current command value Iq ^*, 144 as a result of the comparison in the comparison unit 142, the q-axis current command value Iq ^* is the reference When the q-axis current value Iq _base exceeds the d-axis current command Second primary function calculator for calculating the value Id ^* as the second primary function of the q-axis current command value Iq ^*, 144a may set the proportionality constant _{a 2} is multiplied to the q-axis current command value Iq ^* proportionality constant setting unit which, 144b is a constant setting unit for setting a constant b to be added to the product of the q-axis current command value Iq ^* and the proportionality constant a _2. The comparing unit 142, the result of the comparison, the q-axis current when the command value Iq ^* level is below level of q-axis current value Iq _base of the criteria, the q-axis current command value Iq ^* is the first When the level of the q-axis current command value Iq ^* exceeds the level of the reference q-axis current value Iq _base as a result of the comparison, the q The shaft current command value Iq ^* is input to the second linear function calculator 144. When the q-axis current command value Iq ^* is input to the first linear function calculator 143, the first linear function calculator 143 uses the proportional constant a ₁ to the q-axis current command value Iq ^*. And the product is output as the d-axis current command value Id ^* . When the q-axis current command value Iq ^* is input to the second linear function calculator 144, the second linear function calculator 144 uses the proportional constant to the q-axis current command value Iq ^*. Multiplying a _{2 and} adding a constant b to the product is output as a d-axis current command value Id ^* .

The proportional constants a ₁ and a ₂ used in the current command value converter 14, the calculation and calculation method of the reference q-axis current value Iq _base , the first linear function calculator 143, and the second The processing contents of the linear function calculator 144 will be described below.
In general, the relationship between the d-axis current command value Id ^* and the q-axis current command value Iq ^* when the maximum torque is generated for the same current is obtained from the above formulas 1 and 2 and the following formulas 3 and 4. It is shown by the derived number 5. However, the q-axis inductance Lq and the d-axis inductance Ld of the synchronous motor 100 are assumed to be Lq> Ld.
Iq ^* = − Ia ^* × sin β (Equation 3)
Id ^* = Ia ^* × cosβ (Expression 4)
Id ^* = Фa / {2 (Lq−Ld)}
-[Фa ² / {4 (Lq−Ld) ² } + Iq ^{* 2} ] ^1/2 (Expression 5)
Strictly speaking, the q-axis current command value Iq ^* for generating the maximum torque at the same current is calculated from the above equation 5. However, since the calculation process takes time, the equation 5 is approximated as follows. Then, the q-axis current command value Iq ^* is calculated. That is,
In Equation 5,
Фa / {2 (Lq−Ld)} = A (Expression 6)
From the above formulas 5 and 6, O point (Iq ^* , Id ^* ) = (0, 0), X point (Iq ^* , Id ^* ) = (Iq _base , Id _base ) = (A, (1 −2 ^1/2 ) A), Y point (Iq ^* , Id ^* ) = (Iq _max , Id _max ) = (Iq _max , A− (A ² + Iq _max ² ) ^1/2 ). As shown below, Iq ^* is divided into two ranges and is calculated from a linear function indicating straight lines between the O point and the X point and between the X point and the Y point.

(1) In the range of 0 ≦ Iq ^* ≦ Iq _base ,
Id ^* = (1-2 ^1/2 ) × Iq ^* (Expression 7)
Thus, (1-2 ^1/2 ), which is the slope of the straight line of Equation 7, is set as the proportionality constant a ₁ . Equation 7 is calculated by the first linear function calculator 143.
(2) In the range of Iq _base ≦ Iq ^* ≦ Iq _max ,
Id ^* = [{Id _max − (1-2 ^1/2 ) × A} / (Iq _max −A)] × Iq <sup>*
+ A × {(1-2 1/2)</sup> × Iq max -Id max}} / (Iq max -A) ... ( 8)
Then, [{Id _max − (1-2 ^1/2 ) × A} / (Iq _max −A)], which is the slope of the straight line of Formula 8, is set as the proportionality constant a ₂ , and Iq ^* of the straight line of Formula 8 is set ^. A × {(1-2 ^1/2 ) × Iq _max −Id _max )} / (Iq _max −A), which is the intersection with the axis, is set as a constant b. The number 8 is calculated by the second linear function calculator 144.
The above Iq _max is obtained by using the above equation 3 from β _max when the maximum current value limit value I _{max in} the control device is obtained from the above equation 2.

2, the torque command value T * is inputted to the current command value converter 14, the q-axis current command value Iq ^* is calculated by multiplying the proportional constant K _TI in the q-axis current command value calculator 141. The calculated level of the q-axis current command value Iq ^* is compared with the level of the reference q-axis current value Iq _{base in} the comparison unit 142. As a result of the comparison, when the level of the q-axis current command value Iq ^* is equal to or lower than the level of the reference q-axis current value Iq _base , the first linear function calculator 143 uses the q-axis current command value Iq ^*. Is multiplied by a proportional constant a ₁ , which is output as a d-axis current command value Id ^* . As a result of the comparison, when the q-axis current command value Iq ^* level exceeds the reference q-axis current value Iq _base, in the second linear function calculator 144, the q-axis current command value Iq ^* proportionality constant a ₂ is multiplied by and further the constant b in the laminate has been added is output as a d-axis current command value Id ^* to. The proportionality constant _{K TI} is the q-axis current command value calculator 141, the proportional constant _{a 1} is the proportionality constant setting unit 143a is the proportionality constant _{a 2} is the proportional constant setting section 144a is constant b the constant The setting unit 144b sets the time when the synchronous motor control device 100 is initialized.
2 used in the following description are given the same reference numerals as in FIG.

FIG. 3 is an explanatory diagram of the relationship between the q-axis current command value Iq ^* and the d-axis current command value Id ^{* in} the synchronous motor control device 100 of FIG.
In FIG. 3, the solid line is the characteristic line according to Equations 7 and 8, the dotted line is the characteristic line calculated from the case of Equation 5, which is the theoretical value, and the alternate long and short dash line is irrespective of the range of the q-axis current command value Iq ^* . This is a characteristic line when the d-axis current command value Id ^* is calculated by multiplying the q-axis current command value Iq ^* by a constant proportional constant.

In the synchronous motor control device 100 of FIG. 1, the characteristic line is a solid line in FIG. 3, and when the q-axis current command value Iq ^* is in the range of 0 ≦ Iq ^* ≦ Iq _base , Id ^* = a ₁ × Iq ^* = ( 1-2 ^1/2 ) × Iq ^* , and in the range of Iq _base ≦ Iq ^* ≦ Iq _max , Id ^* = a ₂ × Iq ^* + b = [{Id _max − (1-2 ^1/2 ) × A} / (Iq _max −A)] × Iq ^* + A × {(1-2 ^1/2 ) × Iq _max −Id _max )} / (Iq _max −A).

According to the synchronous motor control device 1 as the first embodiment, the d-axis current command value Id ^* close to the theoretical value can be easily calculated, and the control reliability and control accuracy can be improved. As a result, the synchronous motor 100 can be operated with a stable high torque.

4-5 is explanatory drawing of the 2nd Example of the synchronous motor control apparatus of this invention. FIG. 4 is a configuration example diagram of a synchronous motor control device as a second embodiment, and FIG. 5 is a configuration example diagram of a current command value converter constituting the synchronous motor control device of FIG.
The synchronous motor control device of the second embodiment has a configuration that enables suppression of voltage saturation that occurs when the synchronous motor is operated at high speed or when it is operated under heavy load.

In FIG. 4, 1 ′ is a synchronous motor control device, 100 is a synchronous motor, 11 is an encoder as a position detector that detects the rotational position of a rotor (not shown) of the synchronous motor 100, and 12 ′ is an output of the encoder 11. A speed calculator 13 for calculating the rotational speed and electrical angular speed ω of the rotor of the synchronous motor 100 from the current rotational speed N of the rotor obtained from the speed calculator 12 ′ and a preset speed command value. The speed control computing unit 14 ′, which calculates and outputs the torque command value T ^* from N ^* , calculates the q-axis current command value Iq ^* and the d-axis current command value Id ^* based on the torque command value T ^*. A current command value converter for calculating and outputting, 15 a current detector for detecting the input current value of the synchronous motor 100, and 16 for converting the detected input current value into a q-axis current value Iq and a d-axis current value Id. Axis Current values converter as the U-V-W / d- q converter, 17a is the current command value converter 14 q-axis current command value output from 'and Iq ^*, the U-V-W / d -An addition unit 17b that adds the q-axis current value Iq output from the q-axis converter 16 and subtracts the q-axis current value Iq from the q-axis current command value Iq ^*. The output d-axis current command value Id ^* is added to the d-axis current value Id output from the UVV / dq converter 16, and the d-axis current command value Id ^* is added to the d-axis current. An adding unit 17c for subtracting the value Id adds the preset rotor speed command value N ^* of the synchronous motor 100 and the current speed N of the rotor output from the speed calculator 12, adder for outputting a speed deviation information by subtracting the current speed N from the speed command value N ^*, 1 'Includes a current value deviation information from the q-axis current command value Iq ^* obtained by subtracting the q-axis current value Iq, and a current value deviation information from the d-axis current command value Id ^* obtained by subtracting the d-axis current value Id This is a current control calculator that calculates and outputs the input current value of the synchronous motor 100 based on the above. The controlled input current output from the current control calculator 18 ′ is input to a stator coil (not shown) of the synchronous motor 100, and the synchronous motor 100 is driven. The speed control calculator 13 forms and outputs the torque command value T ^* based on the speed deviation information output from the adder 17c. The current detector 15 and the UVW / dq converter 16 form a feedback control system for the current control calculator 18 ′.

In addition to the torque command value T ^* , the DC voltage Vdc from the current control calculator 18 ′ and the electrical angular velocity ω from the speed calculator 12 ′ are input to the current command value converter 14 ′. As described above, the current control arithmetic unit 18 ′ forms and outputs the q-axis current command value Iq ^* and the d-axis current command value Id ^* . The d-axis current command value Id ^* In this way, it forms and outputs. That is, when the q-axis current command value Iq ^* is less than or equal to the reference q-axis current value Iq _base, first linear function of the first d-axis current command value ^Id _{* 1} of the q-axis current command value Iq ^* calculated as while, q-axis current command value Iq ^* If exceeds the reference q-axis current value Iq _base, the second d-axis current command value ^Id _{* 2} the q-axis current command value Iq ^* of the second Further, a reference electrical angular velocity ω _base is calculated from the DC voltage Vdc, and compared with the electrical angular velocity ω input from the speed calculator 12 ′. When the electrical angular velocity is equal to or higher than ω _base , the d-axis current command increase value Id _ω proportional to the electrical angular velocity ω is calculated, and the first d-axis current command value Id ^* ₁ or the second d-axis current command value is calculated. The d-axis current command increase value Id _ω is added to Id ^* ₂ , and the addition result is added to the d-axis current index. Output as normal value Id ^* .

FIG. 5 is a configuration example diagram of a current command value converter 14 ′ constituting the synchronous motor control device 1 ′ of FIG.
5, 141, multiplies the proportional constant _{K TI} to the torque command value ^{T *} q-axis current command value calculator that calculates and outputs the q-axis current command value Iq ^*, 142 was the output q The comparison unit 143 ′ that compares the level of the shaft current command value Iq ^{* with} the level of the reference q-axis current value Iq _base indicates that the q-axis current command value Iq ^* is the reference value as a result of the comparison by the comparison unit 142. if: q-axis current value Iq _base of the first linear function calculator that calculates a first d-axis current command value Id ^* ₁ as a first linear function of the q-axis current command value Iq ^*, 143a 'is a proportionality constant _{a 1} is multiplied to the q-axis current command value Iq ^*' proportionality constant setting unit for setting a, 144 'a result of the comparison in the comparison unit 142, the q-axis current command value Iq ^* is If the q-axis current value Iq _base is exceeded, the second d-axis current command value Id ^A _second linear function computing unit 144a ′ that calculates ^* 2 as a second linear function of the q-axis current command value Iq ^* has a proportional constant a ₂ ′ multiplied by the q-axis current command value Iq ^*. The proportional constant setting unit 144b ′ for setting sets the constant b ′ to be added to the product of the q-axis current command value Iq ^* and the proportional constant a ₂ ′. A reference electrical angular speed ω _base is calculated from the voltage Vdc and compared with the electrical angular speed ω of the rotor of the synchronous motor. If the electrical angular speed ω exceeds the reference electrical angular speed ω _base as a result of the comparison, The d-axis current command increase value Id _ω proportional to the difference between the angular velocity ω and the reference electrical angular velocity ω _base is calculated and output. As a result of the comparison, the electrical angular velocity ω is less than or equal to the reference electrical angular velocity ω _base . If the third of the d-axis current command increment value Id _omega zero level Linear function calculator, 145a is the electrical angular velocity omega absolute value | omega | absolute value converter for converting the, 145b, the reference angular velocity calculating section for calculating the electrical angular velocity omega _base reference from the DC voltage Vdc, 145c is The absolute value | ω | of the electrical angular velocity ω is compared with the reference electrical angular velocity ω _base, and when the absolute value | ω | exceeds the reference electrical angular velocity ω _base , the difference signal (for convenience, the angular velocity difference On the other hand, when the absolute value | ω | is equal to or less than the reference electrical angular velocity ω _base , the angular velocity comparison unit 145d that makes the output signal zero outputs the angular velocity difference (| ω | -ω it is a proportionality constant setting unit for setting a proportional constant K _omega to multiply the _base). The proportional constant setting unit 145d outputs a d-axis current command increase value Id _{ω of} K _ω × (| ω | −ω _base ). 146 adds the d-axis current command increase value Id _ω to the first d-axis current command value Id ^* ₁ or the second d-axis current command value Id ^* ₂ , and adds the addition result to the d-axis current command. An adder that outputs the value Id ^* .

In the reference velocity calculation unit 145b, the electrical angular velocity omega _base reference for calculating the following Equation 9 from the DC voltage Vdc using a conversion coefficient K _f.
ω _base = K _f × Vdc (Equation 9)
Here, the q-axis inductance of the synchronous motor 100 is Lq, the d-axis inductance is Ld, the linkage flux by the permanent magnet is Φ, the maximum value of the q-axis current value is Iq _max , and the maximum value of the d-axis current value is Id _max , When the voltage utilization factor is λ, the conversion coefficient K _f is
K _f = λ / {(Φa + Ld × Id _max ) ² + (Lq × Iq _max ) ² } ^1/2 (Equation 10)
The value represented by The conversion coefficient _{K f} is set to the reference angular velocity calculating unit 145b. As is clear from the above formula 9, the reference electrical angular velocity ω _base varies with the DC voltage Vdc.

In the angular velocity comparator unit 145c, the rotor of the synchronous motor 100, the electrical angular velocity omega determines whether or the following criteria electrical angular velocity omega _base or exceeds the electrical angular velocity omega _base of the reference. When the electrical angular velocity ω is equal to or less than the reference electrical angular velocity ω _base , the voltage saturation state is not reached, so that the d-axis current command increase value Id _ω output from the third linear function calculator 145 becomes zero level. To. When the electrical angular velocity ω exceeds the reference electrical angular velocity ω _base , the third linear function calculator 145 generates an angular velocity difference (| ω | −ω _base ) to avoid a voltage saturation state. A proportional d-axis current command increase value Id _ω is output. That is,
(1) In the case of 0 ≦ | ω | ≦ ω _base , since the voltage is not saturated, the d-axis current command increase value Id _ω output from the third linear function calculator 145 is
Id _ω = 0 (Expression 11)
It is said.
(2) In the case of ω _base <| ω | ≦ ω _max , in order to avoid a voltage saturation state, the d-axis current command increase value Id _ω output from the third linear function calculator 145 is
Id _ω = K _ω × (| ω | −ω _base ) (Equation 12)
It is said.

The d-axis current command increase value Id _ω calculated by the above equations 11 and 12 is selectively output from the third linear function calculator 145, and the adder 146 outputs the first linear function calculator 143. Is added to the first d-axis current command value Id ^* ₁ output from 'or the second d-axis current command value Id ^* ₂ output from the second linear function calculator 144'.

Similarly to the synchronous motor control device 1 of the first embodiment, the synchronous motor control device 1 'as the second embodiment can easily calculate the d-axis current command value Id ^* close to the theoretical value. Thus, the reliability and accuracy of control can be improved. As a result, the synchronous motor 100 can be operated with a stable high torque. In particular, in the case of the synchronous motor control apparatus 1 ′ according to the second embodiment, a stable high torque operation is possible by avoiding a voltage saturation state even at high speed rotation.

It is a structural example figure of the synchronous motor control apparatus as a 1st Example. It is an example of a structure of the electric current command value converter which comprises the synchronous motor control apparatus of FIG. It is explanatory drawing of the relationship between q-axis current command value Iq ^* and d-axis current command value Id ^{* in} the synchronous motor control apparatus of FIG. It is a structural example figure of the synchronous motor control apparatus as a 2nd Example. It is an example of a structure of the current command value converter which comprises the synchronous motor control apparatus of FIG.

Explanation of symbols

1, 1 '... synchronous motor control device,
100 ... Synchronous motor,
11: Encoder,
12, 12 '... speed calculator,
13 ... Speed control calculator,
14, 14 '... current command value converter,
15 ... current detector,
16 ... U-V-W / dq converter,
17a, 17b, 17c, 146 ... adder,
18, 18 '... current control arithmetic unit,
141... Q-axis current command value calculator,
142 ... comparison part,
143, 143 '... the first linear function calculator,
143a, 144a, 143a ', 144a', 145d ... proportional constant setting unit,
144, 144 '... a second linear function calculator,
144b, 144b '... constant setting unit,
145 ... third linear function calculator,
145a ... absolute value converter,
145b: Reference angular velocity calculation unit,
145c ... Angular velocity comparison unit.

Claims (7)

A synchronous motor control device for controlling an input current of a synchronous motor,
A position detector for detecting the rotational position of the rotor of the synchronous motor;
A speed calculator that calculates the rotational speed of the rotor from the output of the position detector;
A speed control calculator for calculating a torque command value T ^* from a current rotational speed of the rotor obtained from the speed calculator and a preset speed command value;
A current command value converter for calculating a q-axis current command value Iq ^* and a d-axis current command value Id ^* based on the torque command value T ^* ;
A current detector for detecting an input current value of the synchronous motor;
An axial current value converter for converting the detected input current value into a q-axis current value Iq and a d-axis current value Id;
Based on the current value information obtained by subtracting the q-axis current value Iq from the q-axis current command value Iq ^* and the current value information obtained by subtracting the d-axis current value Id from the d-axis current command value Id ^*. A current control calculator that calculates the input current value of the motor and outputs the input current;
Comprising
The current command value converter is
And the q-axis current command value calculator for calculating the q-axis current command value Iq ^* is multiplied by a proportionality constant K _TI to the torque command value T ^*,
A comparison unit that compares the calculated q-axis current command value Iq ^* with a reference q-axis current value Iq _base ;
Result of the comparison, if the q-axis current command value Iq ^* is less than or equal to the q-axis current value Iq _base of the reference, the d-axis current command value Id ^* and the q-axis current command value Iq ^* first of 1 A first linear function calculator that operates as a secondary function;
Result of the comparison, if the q-axis current command value Iq ^* exceeds the q-axis current value Iq _base of the reference, the d-axis current command value Id ^* and the q-axis current command value Iq ^* second of 1 A second linear function calculator that operates as a secondary function;
A synchronous motor control device characterized by comprising: Said first linear function calculator calculates a d-axis current command value Id ^* is multiplied by the proportional constant a ₁ on the q-axis current command value Iq ^*, the second linear function calculator, said q _2. The synchronous motor control device according to claim 1, wherein the d-axis current command value Id ^* is obtained by multiplying a shaft current command value Iq ^* by a proportional constant a2 and further adding a constant b. The reference q-axis current value Iq _base , the proportionality constant a ₂ or the constant b is a function of the linkage flux 永久 by the permanent magnet, the q-axis inductance Lq, the d-axis inductance Ld, and the maximum q-axis current value Iq _max . The synchronous motor control device according to claim 2, which is required.   4. The synchronous motor control device according to claim 1, wherein the current detector and the shaft current value converter form a feedback control system for the current control arithmetic unit. A synchronous motor control device for controlling an input current of a synchronous motor,
A position detector for detecting the rotational position of the rotor of the synchronous motor;
A speed calculator that calculates the rotational speed of the rotor from the output of the position detector;
A speed control calculator for calculating a torque command value T ^* from a current rotational speed of the rotor obtained from the speed calculator and a preset speed command value;
A current command value converter for calculating a q-axis current command value Iq ^* and a d-axis current command value Id ^* based on the torque command value T ^* ;
A current detector for detecting an input current value of the synchronous motor;
An axial current value converter for converting the detected input current value into a q-axis current value Iq and a d-axis current value Id;
Based on the current value information obtained by subtracting the q-axis current value Iq from the q-axis current command value Iq ^* and the current value information obtained by subtracting the d-axis current value Id from the d-axis current command value Id ^*. A current control calculator that calculates the input current value of the motor and outputs the input current;
Comprising
The current command value converter is
And the q-axis current command value calculator for calculating the q-axis current command value Iq ^* is multiplied by a proportionality constant K _TI to the torque command value T ^*,
A comparison unit that compares the calculated q-axis current command value Iq ^* with a reference q-axis current value Iq _base ;
As a result of the comparison, if the q-axis current command value Iq ^* is less than or equal to the reference q-axis current value Iq _base , the first d-axis current command value Id ^* _{1 is changed} to the q-axis current command value Iq ^* . A first linear function calculator that operates as a linear function of 1;
Result of the comparison, if the q-axis current command value Iq ^* exceeds the q-axis current value Iq _base of the reference, the second d-axis current command value Id ^* ₂ of the q-axis current command value Iq ^* A second linear function calculator that operates as a linear function of 2;
When the reference electrical angular velocity ω _base is calculated from the DC voltage Vdc to be converted into AC, and compared with the electrical angular velocity ω of the synchronous motor. As a result of the comparison, when the electrical angular velocity ω exceeds the reference electrical angular velocity ω _base The d-axis current command increase value Id _ω proportional to the difference between the electrical angular velocity ω and the reference electrical angular velocity ω _base is calculated and output. As a result of the comparison, the electrical angular velocity ω is converted into the reference electrical angular velocity ω. _In the case of _base or less, a third linear function calculator that sets the d-axis current command increase value Id _ω to zero level;
The d-axis current command increase value Id _ω is added to the first d-axis current command value Id ^* ₁ or the second d-axis current command value Id ^* ₂ , and the addition result is used as the d-axis current command value Id ^*. An adder that outputs as
A synchronous motor control device characterized by comprising: It said first linear function calculator calculates the first d-axis current command value Id ^* ₁ is multiplied by a proportionality constant alpha ₁ to the q-axis current command value Iq ^*, the second primary function operation 6. The apparatus according to claim 5, wherein the _second multi-axis current command value Id ^* ₂ is obtained by multiplying the q-axis current command value Iq ^* by a proportional constant α2 and adding a constant β to the product. Synchronous motor control device. 6. The configuration according to claim 5, wherein the third linear function calculator is configured to obtain the d-axis current command increase value Id _ω from K _ω (ω−ω _base ) when K _ω is a proportional constant. Synchronous motor control device.

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