WO2013073026A1

WO2013073026A1 - Power conversion device

Info

Publication number: WO2013073026A1
Application number: PCT/JP2011/076432
Authority: WO
Inventors: 誠司石田; 金子　悟; 戸張　和明
Original assignee: 株式会社日立製作所
Priority date: 2011-11-16
Filing date: 2011-11-16
Publication date: 2013-05-23

Abstract

The purpose of the present invention is to suppress the mutual interference between current controllers, and suppress a response to a motor current command and a low-frequency component of a motor current due to the voltage error of a power converter and the like to thereby control the torque of a motor by an adequate response and suppress the low-frequency component of the motor current. To this end, a power conversion device is provided with a power converter for outputting alternating-current voltage on the basis of a voltage command and driving a motor, and a control means for outputting the voltage command such that the torque of the motor matches a torque command, the control means being configured such that when the torque command changes, the rise times of the torque when an angular frequency corresponding to a rotation speed is higher than an angular frequency corresponding to a torque response and when the angular frequency corresponding to the rotation speed is lower become equal, and direct-current components superimposed on an output current on the condition that direct-current disturbance is applied to the output voltage of the power converter become equal.

Description

Power converter

The present invention relates to a power converter, and more particularly to a power converter suitable for controlling an electric motor.

Patent Document 1 is a background art of a power converter suitable for controlling an electric motor. Here, “a control system that performs high-speed current control processing can be configured with a relatively small amount of computation, and for the purpose of obtaining a control device for a power converter having good current control performance, A low-speed calculation unit that performs calculation once per cycle and calculates a voltage command integral term by integral control calculation processing based on a current error between the current command value and the current output value, and 1/5 of the cycle of the low-speed calculation unit The voltage command proportional term is calculated by the proportional control calculation process based on the current error, and the voltage command value is created by the addition process of the voltage command integral term and the voltage command proportional term. It has a high-speed calculation unit. "

Further, Patent Document 2 discloses that “a means for suppressing low-frequency pulsation generated in a motor current is realized by feedback control that can be applied even at a modulation rate of 100%, so that a DC power source, a smoothing capacitor, In the power converter comprised of the power converter, the AC motor, the AC current detecting means, the first coordinate converting means, and the first current control means, the AC current detection detected by the AC current detecting means Means for detecting a low frequency component of the value, and second current control means for operating the AC voltage output from the first power converter so that the low frequency component of the AC current detection value becomes zero. Is described.

JP 2006-296055 A JP-A-11-243700

In the technology of the above-mentioned patent document, a current controller on the rotating coordinate axis that controls the motor current by converting the rotating current coordinate and a current controller on the fixed coordinate axis by converting the motor current command by rotating the coordinate system are used together. As a result, for the motor current command, a highly responsive control can be realized by the current controller on the fixed coordinate axis, and the low frequency component of the motor current caused by the DC component of the voltage due to the conversion error of the power converter is It is expected that the current controller on the fixed coordinate axis will be suppressed.

However, in reality, the two sets of current controllers interfere with each other, so that a sufficient response cannot be obtained. For this reason, when a low frequency component is superimposed on the output voltage due to a conversion error of the power converter, the motor current also includes a low frequency component, which causes torque ripple.

On the other hand, the object of the present invention is to suppress the mutual interference of the current controllers, and to sufficiently reduce the motor torque by suppressing the low frequency component of the motor current due to the response to the motor current command and the voltage error of the power converter. The purpose is to control the low frequency component of the motor current while controlling with a simple response.

In order to solve the above problems, in the present invention, a power converter that outputs an AC voltage based on a voltage command and drives the motor, and a control unit that outputs a voltage command so that the torque of the motor matches the torque command are provided. In the power converter provided, when the torque command is changed, the control means provides torque when the angular frequency corresponding to the rotational speed is higher than the angular frequency corresponding to the torque response and when the angular frequency corresponding to the rotational speed is low. The DC components superimposed on the output current under the condition that the rise times are equal and the DC voltage is applied to the output voltage of the power converter are made equal.

In order to solve the above problems, in the present invention, a power converter that outputs an AC voltage based on a voltage command and drives the motor, and a current command calculation means that calculates a current command so that the torque of the motor matches the torque command. A first current control means for controlling the output current of the power converter on the rotation coordinate axis based on the current command, a second current control means for controlling the output current on the fixed coordinate axis, and a first current control means When the torque command changes, the angular frequency corresponding to the rotational speed is greater than the angular frequency corresponding to the torque response when the torque command changes. The rise time of torque is equal when the frequency is high and when the angular frequency corresponding to the rotational speed is low.

In order to solve the above problems, in the present invention, a power converter that outputs an AC voltage based on a voltage command, a first current control unit that controls a current of the power converter on a rotating coordinate axis, and a fixed coordinate axis In a power conversion device comprising: a second current control unit that controls a current of a power converter; and a voltage calculation unit that calculates a voltage command based on outputs of the first current control unit and the second current control unit. First correction means for correcting the current command for the second current control means based on the current command for the first current control means is provided.

Also, a current command computing unit that obtains a torque command and determines a current command on the rotation coordinate axis is provided, and the current command of the current command computing unit is given to the first current control means and the first correction means.

In addition, the voltage calculation means includes a first voltage signal obtained by converting the output signal on the rotational coordinate axis provided by the first current control means onto the fixed coordinate axis, and a fixed coordinate axis provided by the second current control means. A voltage command for the AC voltage is obtained using the sum signal of the second voltage signal.

In addition, a conversion circuit for converting the AC current of the power converter into a current on the fixed coordinate axis and further converting it into a current on the rotary coordinate axis is provided, and the current on the fixed coordinate axis is used as a feedback signal for the second current control means, The current on the coordinate axis is used as a feedback signal for the first current control means.

Further, it comprises second correction means for correcting the input given to the first current control means based on the output of the second current control means.

In order to solve the above problems, in the present invention, a power converter that outputs an AC voltage based on a voltage command, a first current control unit that controls a current of the power converter on a rotating coordinate axis, and a fixed coordinate axis In a power conversion device comprising: a second current control unit that controls a current of a power converter; and a voltage calculation unit that calculates a voltage command based on outputs of the first current control unit and the second current control unit. The input of the second current control means is corrected based on the current command that is the input of the first current control means, and the input of the first current control means is corrected by the output of the second current control means.

Further, the first correction means corrects the current command based on the control response of the first current control means.

Further, the second correction means obtains the estimated current of the power conversion device with respect to the output of the second current control means, and corrects the current command of the first current control means based on the estimated current.

According to the power converter of the present invention, it is possible to suppress the mutual interference of the current controllers, control the torque of the motor with a sufficient response, and suppress the low frequency component of the motor current.

The figure which shows the structural example of the power converter device of this invention. The block diagram showing the control characteristic of a present Example equivalent to (16) Formula. The time chart which shows the command response when a rotational speed is slow. The time chart which shows the disturbance response when a rotational speed is quick. The time chart which shows the command response when a rotational speed is slow. The time chart which shows the disturbance response when a rotational speed is quick.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram illustrating a configuration example of a power conversion apparatus according to the present embodiment. 1, 1 is an AC power source, 2 is a rectifier, 3 is a smoothing capacitor, 4 is a power converter, 5 is a current detector, 6 is a synchronous motor, 7 is a position detector, and 100 is a control device. is there.

According to this power converter, the AC voltage of the AC power source 1 is converted into a DC voltage by the rectifier 2 and the smoothing capacitor 3, and the output of the control device 100 (three-phase AC voltage commands V _u ^* , V _v ^* , and V _w ^* ) The synchronous motor 6 is driven by converting the DC voltage into an AC voltage having a variable frequency and a variable voltage based on ^* ). The three-phase alternating currents i _u , i _v , and i _w flowing through the synchronous motor 6 are detected by the current detector 5, the magnetic pole position θ of the synchronous motor 6 is detected by the position detector 7, and input.

Based on the torque command T ^* , the three-phase AC currents i _u , i _v , i _w, and the magnetic pole position θ, the control device 100 controls the three-phase AC voltage command so that the torque of the synchronous motor 6 matches the torque command T ^*. V _u ^* , V _v ^* , and V _w ^* are calculated and supplied to the power converter 4.

Hereinafter, a specific circuit configuration of the control device 100 will be described. 101, 102, 110, 111, 115, and 116 are subtractors, 103 is a current controller on the rotational coordinate axis, 104, 109, and 114 are rotational coordinate converters, 105 and 106 are adders, and 107 is two-phase three-phase. The phase converter, 113 is a first compensator, 112 is a current controller on a fixed coordinate axis, 108 is a second compensator, 117 is a three-phase two-phase converter, and 118 is a current command calculator.

In describing the processing in the control device 100, the current i and voltage V are treated as a three-phase AC amount, a fixed coordinate axis amount, and a rotating coordinate axis amount. For this reason, in order to distinguish these, the three-phase alternating current amount is represented by adding signs of U, V, and W meaning each phase, and the quantities on the fixed coordinate axes are signs of a and b meaning the α phase and the β phase. The amount on the rotation coordinate axis is represented by the d and q signs indicating the d axis and the q axis.

In addition, there is one in which a second-digit code is added following these codes applied to the current i and the voltage V. This second-digit code specifies the part that generates the current i and the voltage V. For example, the sign “a” in the second digit is given to the output of the current controller 112 and the output of the first compensator 113 on the fixed coordinate axis. Similarly, “c” is a three-phase to two-phase converter. 117, “d” is given to the output of the current controller 103 on the rotational coordinate axis, the output of the first compensator 108, and the output of the rotational coordinate converter 104, and e is the rotational coordinate converter 114. Is given to the output. Furthermore, “ ^* ” given to the current i and the voltage V means that this is a command value.

The configuration and operation of each part will be described below in accordance with the promise of symbol assignment. First of all, the current command calculator 118 calculates a rotation coordinate current command ( _id ^* , _iq ^* ) based on the torque command T ^* . Here, i _d ^* is a rotation coordinate d-axis current command, and i _q ^* is a rotation coordinate q-axis current command. In the control of FIG. 1, for example, the rotation coordinate d-axis current command i _d ^* is set to 0, and the rotation coordinate q-axis current command i _q ^* is output in proportion to the torque command T ^* .

However, when the rotor of the synchronous motor 6 has saliency, reluctance torque is generated. Therefore, the rotational coordinate d-axis current command i _d ^* is operated so that the loss is minimized, and the rotational coordinate q-axis current command i _q ^* is controlled so that the torque coincides with the torque command T ^* accordingly. Is also possible.

In the present invention, two sets of current controllers are operated based on the rotational coordinate current commands ( _id ^* , _iq ^* ) calculated by the current command calculator 118. One of them is the current controller 103 on the rotation coordinate axis.

Current control on the rotational coordinate axis is performed by the

subtractor

101 and 102 so that the rotational coordinate current (i _de , i _qe ) matches the rotational coordinate current command ( _id ^* , _iq ^* ). And the rotation coordinate current deviation is calculated, and the rotation coordinate voltage commands V _dd ^* and V _qd ^* are calculated by the current controller 103 on the rotation coordinate axis by the equation (1).

In Equation (1), R is the winding resistance of the synchronous motor 6, L _d is the inductance in the magnetic pole position direction (d axis), L _q is the inductance in the direction orthogonal to the magnetic pole (q axis), φ is the magnetic flux, ω Is a rotational angular velocity that can be calculated from the magnetic pole position θ, ω _d is a response angular frequency of the current controller 103 on the rotational coordinate axis, and s is a differential operator.

In the equation (1), the rotational coordinate currents i _de and i _qe are obtained by performing rotational coordinate conversion on the fixed coordinate currents i _ae and i _be after compensation by the rotational coordinate converter 114. The fixed coordinate currents i _ae and i _be after compensation are subtracted from the fixed coordinate currents i _ac and i _bc by the

subtractors

115 and 116, respectively, from the fixed coordinate current compensation amounts i _aa and i _ba that are the outputs of the first compensator 113. It is what I asked for.

Among these, the fixed coordinate currents i _ac and i _bc are obtained by two-phase converting the three-phase alternating currents i _u , i _v , and i _w by the three-phase to two-phase converter 117. In the three-phase to two-phase converter 117, the fixed coordinate currents i _ac and i _bc are obtained from the three-phase alternating currents i _u , i _v and i _w using the equation (2).

On the other hand, in the first compensator 113, the fixed coordinate current compensation amount is calculated from the second rotational coordinate voltage commands V _aa ^* and V _ba ^* , which are the outputs of the current controller 112 on the fixed coordinate axis, by the equation (3). i _aa and i _ba are calculated.

However, the inductances L ₀ and L ₁ are obtained by equations (4) and (5), respectively.

In the rotating coordinate converter 114, the compensated fixed coordinate currents i _ae and i _be which are the outputs of the

subtractors

115 and 116 are converted using the magnetic pole position θ by the equation (6), and the rotating coordinate current i _de , _Find i _qe .

Next, of the two sets of current controllers that operate based on the rotational coordinate current command ( _id ^* , _iq ^* ) calculated by the current command calculator 118, the current on the fixed coordinate axis that is the other current controller. The controller 112 will be described.

The current control on fixed axes, the fixed coordinate current command _{_i} ^a _^*, _i ^b * in a fixed coordinate current _i _ac, so _{i bc} match each fixed coordinate current command and the fixed coordinate

current subtracter

110, 111 This is realized by calculating the second rotation coordinate voltage commands V _aa ^* and V _ba ^* by the equation (7) by the current controller 112 on the fixed coordinate axis.

The fixed coordinate current commands i _a ^* and i _b ^* are derived from the rotational coordinate current commands (i _d ^* and i _q ^* ) guided to the second compensator 108 and compensated for the rotational coordinate current commands (i _dd ^* and i _qd ^*). ), And the rotation coordinate converter 109 further performs rotation coordinate conversion.

Among these, the second compensator 108 obtains the post-compensation rotational coordinate current commands i _dd ^* and i _qd ^* from the rotational coordinate current commands i _d ^* and i _q ^{* using the} equation (8).

Further, the rotational coordinate converter 109 performs coordinate transformation of the compensated rotational coordinate current commands i _dd ^* and i _qd ^* using the magnetic pole position θ according to the equation (9) to obtain fixed coordinate current commands i _a ^* and i _b ^*. Ask for.

Note that the fixed coordinate current compensation amounts i _aa and i _ba were calculated by the first compensator 113 based on the equation (3) using the inverse matrix, but the equation (7) was substituted into the equation (3). It is also possible to calculate from the deviation of the fixed coordinate current commands i _a ^* , i _b ^* and the fixed coordinate currents i _ac , i _bc using the equation (10).

In the embodiment of FIG. 1, the three-phase AC voltage commands V _u ^* and V _v ^* are finally obtained as the sum of the outputs of the two sets of current controllers operated based on the rotational coordinate current commands ( _id ^* , _iq ^* ) ^. , And V _w ^* .

The three-phase AC voltage commands V _u ^* , V _v ^* , and V _w ^* are obtained by converting the third fixed coordinate voltage commands V _a ^* , V _b ^* into three phases by the three-phase two-phase converter 107. It is done. The third fixed coordinate voltage commands V _a ^* and V _b ^* are obtained by adding the second fixed coordinate voltage commands V _aa ^* and V _ba ^* to the first fixed coordinate voltage commands V _ad ^* and V _bd ^* , respectively. It is obtained by adding in the

units

105 and 106.

Here, the second rotation coordinate voltage commands V _aa ^* and V _ba ^* are obtained by executing the expression (7) in the current controller 112 on the fixed coordinate axis.

On the other hand, the first fixed coordinate voltage commands V _ad ^* and V _bd ^* are output from the rotation coordinate voltage commands V _dd ^* and V _qd ^* , which are outputs of the current controller 103 on the rotation coordinate axis, by the rotary coordinate converter 104. Coordinate transformation.

Of the series of processes that finally calculate the three-phase AC voltage commands V _u ^* , V _v ^* , and V _w ^* , the rotary coordinate converter 104 determines from the rotary coordinate voltage commands V _dd ^* and V _qd ^* ( The first fixed coordinate voltage commands V _ad ^* and V _bd ^* are calculated by performing rotational coordinate conversion using the magnetic pole position θ according to equation (11).

In the three-phase to two-phase converter 107, three-phase to two-phase conversion is performed from the third rotation coordinate voltage commands V _a ^* and V _b ^* by the equation (12), and the three-phase AC voltage commands V _u ^* , V _v ^* , And V _w ^* are calculated.

Next, the operation and characteristics of the present embodiment configured as shown in FIG. 1 will be described. First, a response (command response) when the torque command T ^* is changed when control is performed by the control device 100 will be described.

The torque of the synchronous motor 6 is determined by the current. For this reason, the response of the actual torque to the torque command T ^* is determined by the rotation coordinate current commands i _d ^* and i _q ^* and the response of the current of the synchronous motor 6 to the disturbance. Therefore, the current control will be described below.

In this embodiment, the current controller 103 on the rotating coordinate axis performs control for causing the current of the synchronous motor 6 to follow the rotating coordinate current commands i _d ^* and i _q ^* , and the direct current due to the conversion error of the power converter 1 or the like. The current controller 112 on the fixed coordinate axis compensates for low-frequency voltage disturbances including.

Hereinafter, the response when the command is changed will be described as control by the two sets of current controllers. Here, it is assumed that a low-frequency voltage disturbance has not occurred. Further, it is assumed that the second fixed coordinate voltage commands V _aa ^* and V _ba ^{* which} are outputs of the current controller 112 on the fixed coordinate axis are zero. At this time, in the first compensator 113 to which the outputs V _aa ^* and V _ba ^* of the current controller 112 are input, the fixed coordinate current compensation amounts i _aa and i _ba are also 0 as is apparent from the equation (3). Become. As a result, the post-compensation fixed coordinate currents i _ae and i _be coincide with the current on the rotational coordinates of the synchronous motor 6, and the equation (13) is established from the voltage equation of the synchronous motor.

On the other hand, since the characteristic of the current controller 103 on the rotation coordinate axis is expressed by equation (1), the loop gain G (s) is expressed by equation (14).

Further, the rotational coordinate currents i _de and i _qe respond to the rotational coordinate current commands i _d ^* and i _q ^{* by the} equation (15).

The above description shows the characteristics of the current controller 103 on the rotating coordinate axis when it is assumed that no low-frequency voltage disturbance has occurred and the output of the current controller 112 on the fixed coordinate axis is zero. However, when the current controller 112 on the fixed coordinate axis is operated, it becomes a disturbance to the current control on the rotating coordinate axis, and thus the response to the rotating coordinate current command is disturbed. That is, the current control (current controller 112) on the fixed coordinate axis interferes with the current control (current controller 103) on the rotating coordinate axis.

Therefore, in the present invention, the second compensator 108 compensates the current command for the current controller 112 on the fixed coordinate axis. Compared (8) and (15), the rotating coordinate current command _i ^d _*, with respect to _i ^{q *,} the compensated rotational coordinate current command _{_i} ^dd _^*, _i _qd * are rotating coordinate current _i de, i _Since the characteristics of _qe are matched, the deviation is zero. Since this holds even when converted to a fixed coordinate axis, the outputs of the

subtractors

110 and 111 become 0 with respect to the rotational coordinate current commands i _d ^* and i _q ^* .

Thereby, the operation of the current controller 112 on the fixed coordinate axis is suppressed with respect to the rotational coordinate current commands i _d ^* and i _q ^* , and the current control on the fixed coordinate axis (current controller 112) The disturbance to the operation amount of the control (current controller 103) is suppressed, and unnecessary compensation of the fixed coordinate current compensation amounts i _aa and i _ba is also suppressed.

Next, the operation | movement with respect to the low frequency disturbance containing the direct current | flow by the conversion error etc. of the power converter 1 is demonstrated. In the embodiment of FIG. 1, when a low frequency component is superimposed on the three-phase alternating currents i _u , i _v , i _w and fixed coordinate currents i _ac , i _bc due to disturbance, the current controller 112 on the fixed coordinate axis operates, The second rotation coordinate voltage commands V _aa ^* and V _ba ^* are operated.

However, the second rotation coordinate voltage commands V _aa ^* and V _ba ^* are voltage disturbances for the current control (current controller 103) on the rotation coordinate axis. For this reason, the current control on the rotating coordinate axis interferes with the current control on the fixed coordinate axis (current controller 112), and the desired response performance (disturbance response) by the current controller 112 cannot be obtained. Therefore, in the present invention, the first compensator 113 suppresses the operation of the current control (current controller 103) on the rotation coordinate axis with respect to the second rotation coordinate voltage commands V _aa ^* and V _ba ^* .

When the current flowing through the synchronous motor 6 changes in response to the voltage according to the second rotation coordinate voltage command (current controller 103), the current fed back to the current controller 103 on the rotation coordinate axis changes and is suppressed. Thus, the current controller 103 on the rotation coordinate axis operates. For this reason, interference with the current control (current controller 112) on the fixed coordinate axis due to the current control on the rotating coordinate axis occurs.

Therefore, in the present invention, the current of the synchronous motor 6 with respect to the second rotational coordinate voltage commands V _aa ^* and V _ba ^{* is} estimated by the second compensator 113 and fed back to the current controller 103 on the rotational coordinate axis. By subtracting from, current changes with respect to the second rotation coordinate voltage commands V _aa ^* and V _ba ^* are canceled out, and the operation of the current controller 103 on the rotation coordinate axis can be suppressed.

Next, specific current control characteristics by the current controller 103 on the rotation coordinate axis in the present embodiment will be described. When the synchronous motor 6 is modeled by the equation (13), the rotational coordinate motor currents i _d and i _{q with} respect to the rotational coordinate current commands i _d ^* and i _q ^* and the three-phase disturbance voltages ΔVu, ΔVv, and ΔV _w are (16 ).

However, the rotational coordinate motor currents i _d and i _q are values obtained by converting the three-phase alternating currents i _u , i _v , and i _w into the three-phase two-phase conversion and the rotational coordinate conversion based on the magnetic pole position θ according to the equation (17). .

FIG. 2 shows a block diagram equivalent to the equation (16), that is, a block diagram showing the control characteristics of this embodiment. In the block diagram of FIG. 2, the same functions as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 2, 201 is a three-phase to two-phase converter, 202, 203, 207, and 208 are adders, 204 is a motor model on a fixed coordinate axis, 205 is a rotary coordinate converter, and 206 is a motor model on a rotary coordinate axis. is there.

Of these, the three-phase to two-phase converter 201 calculates equation (18).

The motor model 204 on the fixed coordinate axis calculates (19).

Rotational coordinate converter 205 calculates equation (20).

The motor model 206 on the rotation coordinate axis calculates the equation (21).

Next, it will be explained that the equation (16) is the characteristic of the block diagram of FIG. First, when the current control response on the fixed coordinate axis is calculated using the equations (7) and (19), the equation (22) is obtained.

Also, when the current control response on the rotating coordinate axis is calculated using the equations (1) and (21), the equation (23) is obtained.

(16) is obtained by substituting (20) and (22) into (23), it can be seen that the characteristics of (16) and the block diagram of FIG. 2 match. This means that the configuration of FIG. 2 represents the response characteristics of the configuration of FIG.

Next, the response of the rotary coordinate motor currents i _d and i _q to the rotary coordinate current commands i _d ^* and i _q ^* and the three-phase disturbance voltages ΔVu, ΔVv, and ΔV _w will be described with reference to the block diagram of FIG.

The configuration of FIG. 2 can be grasped by dividing it into a lower half rotational coordinate system and an upper half fixed coordinate system. Of these, the lower half rotation coordinate system shows the response to the rotation coordinate current commands i _d ^* and i _q ^* . If this configuration is grasped from the rotation coordinate current commands i _d ^* and i _q ^* , the current controller 103 on the rotation coordinate axis is used as a compensator, the motor model 206 on the rotation coordinate axis is used as a plant, and the rotation coordinate axis currents i _d and i _{q are obtained.} Is a feedback control system using as a feedback signal. Here, it can be seen that there is no interference due to the current control response on the fixed coordinate axis, and a desired control response can be obtained.

On the other hand, the fixed coordinate system of the upper half, the three-phase disturbance voltages ΔVu, ΔVv, shows a response to [Delta] V _w. This arrangement three-phase disturbance voltages ΔVu, ΔVv, when grasped from [Delta] V _w, the current controller 112 on the fixed axis and the compensator, a motor model 204 on the fixed axis and the plant, the second rotating coordinate voltage command V _aa ^This is a disturbance to the manipulated variable of the feedback control system with ^* and V _ba ^* as command values. Therefore, the three-phase disturbance voltages ΔVu, ΔVv, current _i ac for [Delta] V _{_w, i bc} is suppressed by the disturbance suppression characteristics of the fixed coordinate current control.

Furthermore, the currents i _da and i _{qa that} have _undergone rotational coordinate conversion are disturbances to the output of current control on the rotational coordinate axis. From the above, the three-phase disturbance voltages ΔVu, ΔVv, for the [Delta] V _w, act without rotating coordinate current control with a fixed coordinate current control from interfering with each other, the rotating coordinate motor current i _d, i _q is fixed coordinate current It can be seen that the disturbance suppression characteristics of the control and the rotational coordinate current control are characteristics connected in series.

Next, specific response characteristics according to the present embodiment will be described using simulation results. FIG. 3, FIG. 4, FIG. 5 and FIG. 6 show the simulation results of this example. In these figures, time is shown on the horizontal axis. On the vertical axis, as various quantities in FIG. 1, the rotation coordinate d-axis current command i _d ^* , the rotation coordinate d-axis current i _d , the rotation coordinate q-axis current command i _q ^* , the rotation coordinate q-axis current iq, and the three-phase The disturbance voltage ΔV _u and the three-phase current i _u are taken to show the relationship between them.

3, 4, 5, and 6, (a) is a simulation result showing the response of the device of the present invention. (B) and (c) are described for reference in order to clarify the difference in comparison with the response (a) of the device of the present invention. (B) shows only current control on the rotating coordinate axis, and (c) uses both current control on the rotating coordinate axis and current control on the fixed coordinate axis, and compensates by the second compensator 113 and the first compensator 108. It is a simulation result when not performing.

Of these diagrams showing the simulation results, FIGS. 3 and 4 show the characteristics when the torque command T ^* is raised stepwise and the rotational coordinate current command i _q ^* is raised stepwise accordingly. 3 shows a case where the rotation speed is low, and FIG. 4 shows a case where the rotation speed is high. 5 and 6 show characteristics when a step-like three-phase disturbance voltage ΔV _u is applied. FIG. 5 shows a case where the rotational speed is low, and FIG. 6 shows a case where the rotational speed is high.

Current controller on the rotating coordinate axis 103 controls the current of the following angular frequency response angular frequency omega _d. On the other hand, the direct current on the stationary coordinate axes, since the rotation axis is converted to a current of a frequency corresponding to the rotational speed, the angular frequency corresponding to the rotational speed in response angular frequency omega _d greater condition, on fixed coordinate axes The direct current component cannot be controlled.

Therefore, the slow rotational speeds in FIGS. 3 and 5 are cases where the corresponding angular frequency is smaller than the response angular frequency ω _d , and the fast rotational speeds in FIGS. 4 and 5 are equivalent to the response angular frequency ω. _This is the case when it is larger than _d .

As shown in the equation (15), the response of the torque and the rotational coordinate current i _q of the synchronous motor 6 when the torque command T ^* and the rotational coordinate current command i _q ^* are raised in a step shape are the response angular frequency ω. determined by _d . 3 to 6, the torque command T ^* and the torque of the synchronous motor 6 are proportional to the rotational coordinate current command i _q ^* and the rotational coordinate current i _q , respectively, under the simulated conditions ^. The torque characteristics of the synchronous motor 6 are not shown.

In FIG. 3, the horizontal axis is time, and the waveform is the rotational coordinate current i determined from the rotational coordinate current command i _d ^* and the three-phase alternating currents i _u , i _v , and i _w using the equation (17) from the top. _d , rotational coordinate current command i _q ^* , rotational coordinate current iq, three-phase disturbance voltage ΔV _u , and three-phase alternating current _iu . This figure shows the characteristics when the torque command T ^* is raised stepwise at time T1, and the rotational coordinate current command iq ^* is raised stepwise accordingly.

In the present embodiment (a), as in the case of only current control on the rotation coordinate axis (b), the rotation coordinate current i _q rises as designed. On the other hand, in the case where not performed compensation (c), the rotating coordinate current i _q by the interference of the current control on the fixed coordinate axes, and too rise quickly, even for the rotating coordinate current i _d, the interference is seen.

FIG. 4 shows a case where the rotational speed of the synchronous motor 6 is high, and the conditions and waveforms are the same as those in FIG. In particular, the time scale on the horizontal axis is matched with FIG. In this case as well, in this embodiment (a), the rotation coordinate current i _q rises as designed, as in the case of only current control on the rotation coordinate axis (b). On the other hand, when the compensation is not performed (c), the response of the rotational coordinate current _iq is disturbed due to the interference of the current control on the fixed coordinate axis.

Further, from FIGS. 3 and 4, according to this embodiment (a), the rotational speed is faster or slower than the rotational speed corresponding to the response angular frequency ω _d of the current controller on the rotational coordinate axis. When the torque command T ^* and the rotation coordinate current command i _q ^{* with} respect to the torque command T ^* and the rotation coordinate current command i _q ^* are stepped up, the torque and the rotation coordinate current i _q of the synchronous motor 6 have similar responses. To do. For this reason, the index which evaluates a step response is the same value, for example, it will become the same value if the rise time until the torque of the synchronous motor 6 changes from 10% to 90% is compared.

FIG. 5 shows a case where a stepwise three-phase disturbance voltage ΔV _u is applied at time T2 instead of the rotation coordinate current command i _q ^* , and the conditions and waveforms are the same as those in FIG. However, the horizontal axis represents a longer time than that in FIGS. In this embodiment (a), it can be seen that the rotational coordinate currents i _d and i _q are hardly affected by the three-phase disturbance voltage ΔV _u , and the disturbance is sufficiently suppressed. On the other hand, in the case of only current control on the rotation coordinate axis (b), large vibrations are generated in the rotation coordinate currents _id and _iq . Even in the case where the compensation is not performed (c), the vibration remains in the rotational coordinate currents _id and _iq , although it is smaller than in the case of only the current control on the current rotational coordinate axis (b).

FIG. 6 shows a case where the rotational speed of the synchronous motor 6 is faster than that in FIG. 4, and the conditions and waveforms are the same as those in FIG. In this example if you did not (a) and compensation (c), the three-phase disturbance voltage [Delta] V _u According affect little the rotating coordinate current i _d and i _q, that disturbance suppression with adequate Recognize. On the other hand, when only the current control of the current rotational axis (b), a large vibration is generated in the rotating coordinate current i _d and i _q, the DC component is superimposed to the three-phase alternating currents i _u.

Further, from the steady state of FIGS. 5 and 6, according to this embodiment (a), even when the rotational speed is faster than the rotational speed corresponding to the response angular frequency ω _d of the current controller on the rotational coordinate axis, it is slow. Even in this case, it can be seen that the DC component of the three-phase alternating current i _u is equal to the three-phase disturbance voltage ΔV _u .

In summary, in this embodiment (a), good command response and disturbance response can be realized regardless of the rotational speed. On the other hand, in the case of only current control on the rotation coordinate axis (b), the suppression of the disturbance response is insufficient, particularly when the rotation speed is high. Further, when the compensation is not performed (c), there is a problem in the command response, and the disturbance response when the rotational speed is slow is also inferior to the present embodiment.

4: power converter, 103: current controller on rotating coordinate axis, 112: current controller on fixed coordinate axis, 104: rotating coordinate converter, 105, 106: adder, 107: two-phase three-phase converter, 113 : Second compensator, 108: first compensator

Claims

In a power converter including a power converter that outputs an AC voltage based on a voltage command and drives the motor, and a control unit that outputs the voltage command so that the torque of the motor matches the torque command.
When the torque command changes, the control means has an equal torque rise time when the angular frequency corresponding to the rotational speed is higher than the angular frequency corresponding to the torque response and when the angular frequency corresponding to the rotational speed is low, The power converter is characterized in that the DC component superimposed on the output current under the condition that a DC disturbance is added to the output voltage of the power converter is equalized.
A power converter that outputs an AC voltage based on the voltage command and drives the motor, a current command calculation means that calculates a current command so that the torque of the motor matches the torque command, and a rotational coordinate axis based on the current command First current control means for controlling the output current of the power converter, second current control means for controlling the output current on a fixed coordinate axis, the first current control means and the second current control means In a power conversion device comprising voltage calculation means for calculating a voltage command based on the output of
When the torque command changes, the power is characterized in that the rise time of the torque is equal when the angular frequency corresponding to the rotational speed is higher than the angular frequency corresponding to the torque response and when the angular frequency corresponding to the rotational speed is low Conversion device.
A power converter that outputs an alternating voltage based on a voltage command; first current control means for controlling the current of the power converter on a rotating coordinate axis; and a second that controls the current of the power converter on a fixed coordinate axis. In the power conversion device comprising: the current control means; and the voltage calculation means for calculating the voltage command based on the outputs of the first current control means and the second current control means,
A power conversion apparatus comprising: a first correction unit that corrects a current command to the second current control unit based on a current command to the first current control unit.
The power conversion device according to claim 3,
A current command computing unit that obtains a torque command and determines a current command on the rotational coordinate axis is provided, and the current command of the current command computing unit is given to the first current control means and the first correction means. A power converter.
In the power converter device according to claim 3 or claim 4,
The voltage calculation means includes a first voltage signal obtained by converting an output signal on the rotational coordinate axis provided by the first current control means onto a fixed coordinate axis, and a fixed coordinate axis provided by the second current control means. A power converter that obtains a voltage command of the AC voltage using a sum signal of the second voltage signal.
In the power converter device in any one of Claims 3-5,
A conversion circuit that converts the alternating current of the power converter into a current on a fixed coordinate axis, and further converts it into a current on a rotary coordinate axis, and uses the current on the fixed coordinate axis as a feedback signal of the second current control means; A power conversion apparatus characterized in that the current on the rotation coordinate axis is used as a feedback signal of the first current control means.
In the power converter device in any one of Claims 3-6,
A power converter comprising: second correction means for correcting an input given to the first current control means based on an output of the second current control means.
A power converter that outputs an alternating voltage based on a voltage command; first current control means for controlling the current of the power converter on a rotating coordinate axis; and a second that controls the current of the power converter on a fixed coordinate axis. In the power conversion device comprising: the current control means; and the voltage calculation means for calculating the voltage command based on the outputs of the first current control means and the second current control means,
Correcting the input of the second current control means based on the current command which is the input of the first current control means, and correcting the input of the first current control means with the output of the second current control means. A power conversion device.
In the power converter device in any one of Claims 3-8,
The power converter according to claim 1, wherein the first correction unit corrects a current command based on a control response of the first current control unit.
In the power converter device in any one of Claims 3-9,
The second correction unit obtains an estimated current of the power conversion device with respect to an output of the second current control unit, and corrects a current command of the first current control unit based on the estimated current. Power converter.