JP4855274B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device including a power converter that drives an induction machine such as an induction motor, and in particular, the AC output of the power conversion device is interrupted due to a power failure or the like during operation, so that it is in a free-running state. This technology relates to a technology for quickly restarting the induction machine at.

When restarting an induction rotating machine that is rotating without being driven by the power converter, the frequency, phase, and amplitude of the output voltage supplied from the power converter are set to the rotational frequency of the induction rotating machine in the free-run state. It is necessary to match the residual voltage phase and amplitude.
If there is a difference in voltage phase and amplitude, a large current flows through the power converter, and if there is a difference in frequency, a sudden torque is generated in the induction rotating machine.
For this reason, based on the rotational speed detected by some means, the frequency of the power converter (inverter) is fixed at a frequency commensurate with the detected rotational speed, and the voltage corresponding to the frequency is returned to normal operation. There has been proposed a method of gradually increasing the distance (see Patent Document 1, for example).

JP-A-61-98188

  Thus, in the method shown in the conventional patent document 1, after detecting the rotation frequency of the induction rotating machine during free run, the output frequency of the power conversion device is fixed to a frequency commensurate with the detected rotation speed, The voltage is gradually increased to return the voltage to the value during normal operation. For this reason, it takes a long time to return to the normal operation state after the restart is instructed.

  The present invention has been made to solve the above-described problem, and provides a power conversion device capable of restarting an induction machine in a free-run state in a minimum short time without a torque shock. The purpose is to do.

The power conversion device according to the present invention includes a power converter that outputs a voltage based on a predetermined voltage command and drives the induction machine, and the power converter stops the output and starts the induction machine in a free-run state. In the power conversion device that restarts the power converter based on the
Speed detection means for detecting the free-run speed, which is the speed of the induction machine in the free-run state under the condition that the induction machine does not generate torque based on the start command, and according to the free-run speed based on the predetermined operation control characteristics of the induction machine Second voltage command calculation means for calculating the second voltage command to be set, and the power command at which the power converter is restarted and the voltage command to the power converter is detected when the free-run speed is detected by the speed detection means. A means for performing transition control from the first voltage command, which is a voltage command to the converter, to the second voltage command, wherein the transition of the voltage command is determined by a circuit constant of the induction machine in a free-run state. This is provided with voltage command transition means for performing constant primary delay transmission control.

  As described above, in the present invention, the transition from the first voltage command at the time when the free-run speed is detected to the second voltage command corresponding to the free-run speed, that is, from the free-run state to the operating state. Since the return control is performed by the first-order lag transmission control of the second-order time constant determined by the circuit constant of the induction machine, the phenomenon of the electric circuit including the induction machine changes critically, resulting in torque shock. Without restarting, it can be restarted in a minimum amount of time.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a configuration diagram illustrating a power conversion device according to Embodiment 1 of the present invention. A power converter 2 that converts direct current into alternating current at an arbitrary frequency applies a three-phase voltage to the induction machine 1 that is an induction rotating machine.
The AC side current detection means 3a, 3b, 3c detect the phase currents iu, iv, iw flowing through the induction machine 1. Although FIG. 1 describes what detects the electric current which flows through the connection which connects the power converter 2 and the induction machine 1 by CT etc. as the current detection means 3 by the side of alternating current, other well-known methods are used. Thus, the phase current may be detected from the current flowing in the power converter 2 such as the bus current.
Further, since the relationship of iu + iv + iw = 0 is established, the w-phase current detection means 3c may be omitted because the w-phase current can be obtained from the detected currents for the u and v2 phases.

  Hereinafter, a case where an induction rotating machine such as an induction motor is applied as the induction machine 1 will be described. However, the present invention is also applied to an induction linear machine such as a linear induction motor and an induction machine that drives and controls an actuator such as a solenoid. Needless to say, the same effect can be expected in the same principle.

Note that, as is commonly used, when coordinate conversion of three-phase voltage or three-phase current to rotation orthogonal two axes is required, a control coordinate axis is required, but the rotation two-axis coordinates are based on a predetermined angular frequency ω. Let the phase of the control coordinate axis be θ. This phase θ is a value obtained by integrating the predetermined angular frequency ω by the phase calculating means 7.
This phase calculation means 7 integrates a predetermined angular frequency ω to obtain a phase θ, which is a three-phase / dq axis conversion means 10 in the first voltage command calculation means 5 and a dq axis / three-phase in the voltage command switching means 4. Output to the conversion means 15.

The power converter of the present invention is characterized by speed detecting means 9 for detecting a free-run speed ωe, which is the speed of the induction machine 1 in a free-run state on the condition that the induction machine 1 does not generate torque based on the start command, First voltage command calculation means 5 for calculating first voltage commands Vd1 and Vq1, which are voltage commands to the power converter 2 at the time when the free-run speed ωe is detected by the detection means 9, and a predetermined voltage of the induction machine 1 The second voltage command calculation means 6 for calculating the second voltage commands Vd2 and Vq2 set according to the free-run speed ωe based on the operation control characteristics of the power converter 2 and the voltage command to the power converter 2 are A means for performing transition control from the voltage commands Vd1, Vq1 to the second voltage commands Vd2, Vq2, and the primary time constant Ts determined by the circuit constant of the induction machine 1 in the free-run state. Lateness In that a voltage command switching means 4 as the voltage command shifting unit to perform the control.
Hereinafter, each part will be described in detail.

  The first voltage command calculation means 5 shown in FIG. 1 integrates phase currents iu, iv, iw flowing in the induction machine 1 detected by the current detection means 3a, 3b, 3c on the AC side with a predetermined angular frequency ω. Three-phase / dq-axis conversion means 10 for converting the detected d-axis current value id of the rotation biaxial coordinates (dq axes) and the q-axis current detection value iq based on the phase θ obtained in this way, and speed detection And means 9.

FIG. 2 is a configuration diagram showing the speed detection means 9 in the first voltage command calculation means 5 according to the first embodiment of the present invention. The speed detection means 9 operates immediately after the activation signal indicating that the power converter is activated. In that case, similarly, the power converter 2 operates in response to the activation signal or is in an operable state.
The speed detection means 9 calculates the magnetic flux amplitude based on the value obtained by subtracting the d-axis resistance voltage drop from the d-axis voltage on the rotating two axes (dq axes) rotating in synchronization with the angular frequency of the output voltage, The value obtained by subtracting the q-axis resistance voltage drop from the q-axis voltage is divided by the magnetic flux amplitude to calculate the angular frequency ω of the induction machine during the free run.
In the figure, the angular frequency output from the speed detecting means 9 uses the sign of ωe to distinguish it from the angular frequency ω output from the angular frequency generating means 29 described later. Is simply referred to as ω.

  The calculation of the angular frequency ω calculated by the speed detection means 9 will be described. When the rotating two axes (dq axes) are rotating at a predetermined angular frequency ω, the d-axis component φd and the q-axis component φq of the armature magnetic flux of the induction machine 1 are expressed by equations (1) and (2). it can.

  Here, R is an armature resistance. The torque τm output from the induction machine 1 is proportional to the magnitude of the outer product of the armature magnetic flux and the armature current, and can be expressed by the equation (3).

  When the d-axis direction of the two rotating shafts matches the direction of the armature magnetic flux, φq = 0. Therefore, when φq = 0 is substituted into the equations (1) and (2), equations (4) and (5) are obtained.

That is, if the rotating two axes (dq axes) are rotated in synchronization with the angular frequency ω calculated according to the equations (4) and (5), the d-axis direction of the rotating two axes and the armature magnetic flux The direction matches.
Therefore, as shown in FIG. 2, the speed detection means 9 performs the calculation of the right side of the equation (4) by the resistance value gain (multiplier) 17d, the subtractor 14d, and the integrator 18, and the resistance value gain (multiplier). 17q, the subtracting means 14q, and the divider 19 calculate the right side of the equation (5) to obtain the angular frequency ω (ωe).
Since the two rotation axes (dq axes) are determined so as to rotate in synchronization with the angular frequency ω obtained in this way, the d axis direction and the direction of the armature magnetic flux are made to coincide, and the q axis armature magnetic flux is determined. φq = 0 can be maintained.

FIG. 3 shows an internal configuration example of the current control means 16. In the current control means 16, the d-axis current id and the q-axis current iq are controlled to follow the d-axis current command id ^* and the q-axis current command iq ^* by the equations (6) and (7), First voltage commands Vd1 and Vq1 are calculated.

Here, p1 and p2 are gains of the respective transfer elements.
The q-axis current command iq ^* is set to zero, so that the q-axis current iq can be kept zero, and the speed of the induction machine 1 during free run can be detected without generating unnecessary torque. There is. Note that a predetermined value may be given to the d-axis current command id ^* , and for example, it may be given by a step-like or first-order lag characteristic having a predetermined value.

The speed detection means 9 receives a start signal and operates only for a predetermined time set by the first voltage command calculation means selection time setting means 28 in the switching condition setting means 8 shown in FIG. The time set here is set as a time necessary and sufficient for calculating an accurate angular frequency ωe in consideration of the operating time characteristics of the speed detecting means 9 including the equations (6) and (7).
As a specific setting example of this time, for example, setting to about 30 ms to 100 ms is conceivable. The lower limit of 30 ms is set from the time required to obtain a steady solution in consideration of the current control response of the current control means 16 expressed by equations (6) and (7).
For the upper limit of 100 ms, the speed needs to be detected in a state where no current flows through the secondary side of the induction machine 1, and therefore, it is determined by the circuit constant of the induction machine 1. This upper limit is set because it should be kept at the following time.
FIG. 5 is a diagram illustrating an example of the relationship between the activation signal and the switching condition signal.

  As described above, the voltage command to the power converter 2 at the time when the angular frequency ωe that is the free-run speed is obtained by the speed detection unit 9 is the first voltage command Vd1, Vq1 output from the current control unit 16. It is. However, the values of the first voltage commands Vd1 and Vq1 do not necessarily match the voltage corresponding to the free run speed ωe on the operation control characteristics of the induction machine 1. In the present application, the latter voltage is referred to as a second voltage command, and the purpose of the present application is to promptly make a transition from the first voltage command to the second voltage command. A method for obtaining the voltage command will be described.

  FIG. 6 shows an example of the internal configuration of the second voltage command calculation means 6. 6 calculates the second d-axis voltage command Vd2 by multiplying the primary resistance value Rs of the induction machine 1 by a predetermined coefficient k by the multiplier 20. The coefficient k may be a d-axis current command value determined by the characteristics of the induction machine 1. The second q-axis voltage command Vq2 is a V / f pattern 21 in which a pattern of a predetermined voltage and speed (angular frequency) is set by table data with the angular frequency ωe output from the speed detecting means 9 as an input. The voltage command is output from.

  Needless to say, the second voltage command calculation means 6 may use the following equations (8) and (9) as vector control.

Next, after the speed detecting means 9 can accurately detect the speed during the free run, the second voltage command calculating means 6 calculates from the first voltage command (Vd1, Vq1) which is the output of the speed detecting means 9. The voltage command switching means 4 shown in FIG. 7, which is a means for shifting to the second voltage command (Vd2, Vq2), will be described.
7 includes subtractors 14d and 14q, adders 12d and 12q, switchers 13d and 13q, first-order lag transmission means 11d and 11q, and dq axis / three-phase conversion means 15.

First, the operation of the q-axis voltage command Vq will be described using the operation example of FIG. When the activation signal is input (time t1 in FIG. 8), the power conversion device calculates the q-axis voltage command Vq1 by the speed detection unit 9 and sets the predetermined voltage set by the first voltage command calculation unit selection time setting unit 28. (Time t2 in FIG. 8), the speed detector 9 stops and holds the value of the q-axis voltage command Vq1 at that time.
When a predetermined time set by the first voltage command calculation means selection time setting means 28 has passed since the start signal was input (time t2 in FIG. 8), the switching condition signal is turned ON, and the voltage command switching means 4 The switch 13q is switched to the upper side, Vq1 is subtracted from the Vq2 calculated by the second voltage command calculation means 6 by the subtractor 14q, and the subtracted value is the primary of the induction machine 1 by the primary delay transmission means 11q. The time constant (primary inductance / primary resistance) is output through the primary delay with the secondary time constant Ts, and the value obtained by adding the first voltage command Vq1 to the value by the adder 12q is output as the q-axis voltage command Vq. To do.

  The d-axis voltage command Vd is also switched by the same operation as the q-axis voltage command Vq when a predetermined time set by the first voltage command calculation means selection time setting means 28 has passed since the start signal was input. The condition signal is turned ON, and the voltage command switching means 4 switches the switch 13d to the upper side, subtracts Vd1 from Vd2 calculated by the second voltage command calculation means 6 by the subtractor 14d, and subtracts the subtracted value. The primary delay transmission means 11d outputs the primary time constant (primary inductance / primary resistance) of the induction machine 1 through the primary delay with the secondary time constant Ts, and the first voltage command Vd1 is added to the value as an adder 12d. The value added at step d is output as the d-axis voltage command Vd.

  Then, the d-axis voltage command Vd and the q-axis voltage command Vq are changed from the voltage commands Vd and Vq of the rotating biaxial coordinates (dq axes) to the three-phase voltage command based on the phase θ which is the output of the phase calculation means 7. It is converted into three-phase voltage commands Vu, Vv, Vw by the dq axis / three-phase conversion means 15 that converts and outputs it, and is output to the power converter 2.

  Next, a voltage command is given from the first voltage command by using the primary time constant (primary inductance / primary resistance) of the induction machine 1 as a time constant by the first-order lag transmission means 11, which is a feature of the present invention. The theoretical basis for the quick transition to the voltage command 2 will be described.

  FIG. 9 is a general equivalent circuit of the induction machine 1, but when the speed detection means 9 detects the number of rotations of the induction machine 1 during free run, it is considered that the slip slip = 0 in FIG. Therefore, the equivalent circuit of the induction machine 1 is in a state where the secondary side circuit of FIG. 9 is opened, and can be regarded as an equivalent circuit of only the primary side as shown in FIG.

  Next, using the equivalent circuit of FIG. 10, the primary inductance Ls = ls + M is set, and the current that flows when the next AC voltage Vs is applied to the RsLs series circuit is calculated. That is, after the speed is detected by the speed detector 9, the current i when the AC voltage is step-applied is calculated.

  Let the flowing current be i, and the differential equation (11) of the equivalent circuit of FIG. 10 is established.

  When formula (11) is Laplace transformed, formula (12) is obtained.

  When I (s) is expanded into partial fractions using the initial condition i (0) = 0, the result is as follows.

  Therefore, Expression (17) is obtained from Expressions (13) to (16).

  Therefore, when the current i is obtained by reverse conversion, the equation (18) is obtained.

  From the equation (18), when the initial phase θ of the AC voltage is θ = 0 and the analysis is simplified, the following equation is obtained.

  Equation (19) is the result of obtaining the current i when the AC voltage of the step after the speed detection by the speed detection means is applied.

  From equation (19), the first term on the right side

Is a steady term of the current i that flows when an AC voltage of equation (10) is applied to the induction machine 1.
Second term on the right side

Becomes the transient term when the AC voltage is stepped, and this second term

By applying a voltage that minimizes the current flowing, the flowing current can be minimized.
Therefore, next

As a formula (20), a voltage amplitude Em that minimizes the formula (20) is examined.

  In order to minimize the equation (20), the equation (20)

Than

It is sufficient that the product of is minimized. That is, when Rs / Ls> 0, the time when the following expression (21) holds is considered to be the minimum.

  The voltage amplitude Em that satisfies the equation (21) is the equation (22).

  Further, when Formula (22) is Laplace converted, Formula (23) is obtained.

From the above, by giving the voltage amplitude Em of the first order lag with the time constant (secondary time constant) Ls / Rs of the circuit constant of the induction machine 1 (primary inductance Ls / primary resistance), torque shock can be achieved in the shortest time. It was theoretically proved that the induction machine 1 can be restarted without the need.
Therefore, the present invention has an effect that it is possible to provide a power converter that restarts the induction machine without torque shock in the shortest time regardless of whether the induction machine is stopped or free running.

  FIG. 11 shows the result of confirming the operation by simulation in order to confirm the effect. FIG. 11 shows that the power converter that controls the induction machine that is free running at 60 Hz is activated by the activation signal at time 0.01 sec, detects the speed during free run by the speed detection means 9 until time 0.11 sec, From time 0.11 sec, the voltage command switching means 4 outputs the first voltage commands Vd1 and Vq1 output from the speed detection means 9 to the second voltage commands Vd2 and Vq2 calculated by the second voltage command calculation means 6. The voltage is switched by time 0.75 sec by the first-order lag transmission of the constant Ls / Rs. Then, the power converter is controlled by the second voltage command calculated by the second voltage command calculation means 6 from time 0.75 sec.

  As can be confirmed from FIG. 11 of the simulation result, the U-phase voltage waveform applied to the induction machine 1 and the U-phase current waveform flowing through the induction machine 1 are stable, and the induction machine 1 without torque shock in the shortest time. Can be confirmed.

By the way, after shifting to the voltage commands Vd2 and Vq2 calculated by the second voltage command calculation means 6, the angular frequency ωe is set to a predetermined angular frequency command ω set from the original operating characteristics of the induction machine 1. ^It is necessary to move to ^* . Similarly to the voltage command, the angular frequency ω is shifted by the first-order lag transmission unit 31 using the predetermined angular frequency command ω ^* as a target value by the angular frequency generation unit 29 shown in FIG.

  The voltage command transition time setting means 30 of the angular frequency generation means 29 shown in FIG. 12 is a means for setting a predetermined time until the second voltage command calculated by the second voltage command calculation means 6 is reached. The predetermined time set here may be set to a time longer than the secondary time constant Ls / Rs of the circuit constant of the induction machine 1 (primary inductance Ls / primary resistance). For example, Tv = Ls / Rs By setting the time of x5, it can be said that the transition of the voltage command is completed with certainty and is the second voltage command calculated by the second voltage command calculation means 6.

Immediately after starting or restarting the power converter 2, the angular frequency generation means 29 shown in FIG. 12 outputs the angular frequency calculation value ωe, which is the output of the first voltage command calculation means 5, as the angular frequency ω. After the switching condition signal, which is the output of the condition setting means 8, is input and set in the voltage command transition time setting means 30, a predetermined time until the voltage command becomes the second voltage command elapses, then the angular frequency calculation The value ωe is set as an initial value, a predetermined angular frequency command ω ^* is set as a target value, and is increased by first-order lag transmission to shift the angular frequency ω to the predetermined angular frequency command ω ^* .

That is, after a predetermined time until the voltage command becomes the second voltage command after the switching condition signal is turned ON and set in the voltage command transition time setting unit 30, the switch 13 switches to the upper side, The angular frequency calculation value ωe is subtracted from the predetermined angular frequency command ω ^* by the subtractor 14, and the subtracted value is passed through the primary delay transmission means 31 of the time constant Tv, and the angular frequency calculation is performed on the value output through the primary delay transmission means 31. The value ωe is added by the adder 12, and the value is shifted to the angular frequency ω. As a result, it is possible to shift to the predetermined angular frequency command ω ^* by first-order lag transmission, to shift to the predetermined angular frequency command ω ^* in a short time, and to quickly return to normal control. The time constant Tv of the primary delay transmission means 31 is a predetermined constant close to the time constant Ls / Rs of the circuit constant (primary inductance Ls / primary resistance) of the induction machine 1 or the secondary time constant Ls / Rs. A value should be set.

  As described above, according to the first embodiment of the present invention, the speed detector that directly detects the rotation of the induction machine is not required, and the shortest time can be obtained regardless of whether the induction machine is stopped or free running. The induction machine can be restarted without torque shock in time.

Embodiment 2. FIG.
FIG. 13 is a configuration diagram illustrating a configuration example of the power conversion device according to the second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Only different parts will be described here.
Here, the voltage command transition processing is performed on the voltage amplitude command as the transition target. Therefore, the first voltage amplitude command calculating means 25, the second voltage amplitude command calculating means 24, the voltage amplitude command switching means 22, and the three-phase voltage command calculating means 23 are provided. Hereinafter, these will be mainly described.

  The first voltage amplitude calculation means 25 receives the first voltage commands Vq1 and Vd1 that are the outputs of the first voltage command calculation means 5, and calculates the first voltage amplitude command V1 by the following equation (24). To do.

  The second voltage amplitude command calculation means 24 has the configuration shown in FIG. 14 and receives an angular frequency ωe that is the output of the speed detection means 9 in the first voltage command calculation means 5 as an input, and a predetermined voltage and speed (angle). The second voltage amplitude command V2 is output from the V / f pattern 27 in which the frequency) pattern is set by table data.

  The voltage amplitude command switching means 22 has the configuration shown in FIG. 15, and a predetermined time set by the first voltage command calculation means selection time setting means 28 of the switching condition setting means 8 has passed after the activation signal is input. Then, the switching condition signal is turned ON and input to the voltage amplitude switching means 22. Thereby, the switch of the switch 13 is switched to the upper side, and the first voltage amplitude command calculating means 25 calculates the first voltage amplitude command V2 calculated by the second voltage amplitude command calculating means 24. The voltage amplitude command V1 is subtracted by the subtractor 14, and the subtracted value is output by the primary delay transmission means 11 through the primary delay transmission with the primary time constant (primary inductance / primary resistance) of the induction machine as the time constant Ts. The value obtained by adding the first voltage amplitude command V1 to the added value by the adder 12 is output to the three-phase voltage command calculation means 23 as the voltage amplitude command V. Therefore, the induction machine 1 can be restarted in the shortest time without torque shock by shifting the optimal control constant (primary inductance / primary resistance) as the secondary time constant Ts by the first-order lag transmission of the voltage command amplitude. It is possible to realize a power converter that performs the above.

  The configuration shown in FIG. 16 is an example of the configuration of the three-phase voltage command calculation means 23. The three-phase sine wave generation means 26 generates a three-phase sine wave based on the phase θ output from the phase calculation means 7, and the multiplier The voltage amplitude command V, which is the output of the voltage amplitude command switching means 22, is multiplied by the three-phase sine wave by 20u, 20v, and 20w. The three-phase voltage commands Vu, Vv, Vw calculated by the three-phase voltage command calculating means 23 can be expressed as the following equation (25) as the voltage amplitude V and the phase θ.

  Three-phase voltage commands Vu, Vv, Vw calculated by the three-phase voltage command calculation means 23 are output to the power converter 2. The power converter 2 operates based on the three-phase voltage commands Vu, Vv, and Vw.

  As described above, according to the second embodiment of the present invention, the speed detector that directly detects the rotation of the induction machine is not required, and the shortest time can be obtained regardless of whether the induction machine is stopped or free running. The induction machine can be restarted without torque shock in time. Further, there is an advantage that the configuration of the voltage amplitude command switching means 22 that is the voltage command transition means is simpler than the configuration of the voltage command switching means 4 that is the voltage command transition means in the first embodiment.

Embodiment 3 FIG.
In any of the previous embodiments, the speed and angular frequency are obtained by calculation by the speed detection means 9 without providing a speed detector that directly detects the rotation of the induction machine 1, but the speed detector is used. Thus, the present invention can also be applied to the case where the speed and angular frequency are directly obtained, and the same effects as described above can be obtained.
In this case, when the angular frequency in the free-run state is detected by the speed detector, the voltage of the power converter 2 is zero, the first voltage command is set to zero, and this is set to the initial value. Then, the transition process to the second voltage command is performed by the voltage command switching means 4 or the voltage amplitude command switching means 22.

  Further, in each modification of the present invention, the speed detecting means restarts the power converter under the condition that the induction machine does not generate torque based on the start command, and the speed calculating means detects the free run speed from the operation characteristics by calculation. The voltage command transition means uses the first voltage command as the voltage command to the power converter at the time when the free-run speed is detected by the speed calculation means. The voltage command can be obtained by calculation without requiring a speed detector that directly detects the speed of the induction machine.

Further, a phase calculating means for calculating the phase θ of the rotating biaxial coordinates (dq axes) based on the output of the speed detecting means, and the three-phase current detection value of the induction machine based on the phase θ, the rotating biaxial coordinates (d− (q-axis) d-axis current id, three-phase / dq-axis conversion means for converting to q-axis current iq, and d-axis current command id ^* and zero that d-axis current id and q-axis current iq are set to predetermined values, respectively. Since the first voltage command calculation means for outputting the first voltage commands Vd1 and Vq1 of the rotating biaxial coordinates (dq axes) so as to follow the q-axis current command iq ^* set to The first voltage commands Vd1 and Vq1 on the rotating biaxial coordinates corresponding to the accurate speed in the free-run state can be obtained without generating torque.

  Further, the speed detection means calculates the magnetic flux amplitude φd based on the value obtained by subtracting the d-axis resistance voltage drop due to the d-axis current id from the first voltage command Vd1, and based on the q-axis current iq from the first voltage command Vq1. Since the free run speed is calculated by dividing the value obtained by subtracting the q-axis resistance voltage drop by the magnetic flux amplitude φd, the free run speed can be obtained by calculation without requiring a speed detector.

  Further, the speed detection means is a speed detector that directly detects the speed of the induction machine in the free-run state, and the voltage command transition means sets the first voltage command to zero. Based on the free-run speed, the induction machine can be restarted without torque shock in the shortest time regardless of whether the induction machine stops or is free-running.

  In addition, the second voltage command calculating means has a predetermined value of Vd2 and the output of the speed detecting means of the rotating biaxial coordinates (dq axes) rotating in synchronization with the output from the speed detecting means and a predetermined value. Since Vq2 based on the voltage / frequency (V / f) pattern is output as the second voltage command, the second voltage command that is the target value for the voltage command shift can be obtained easily and reliably.

  The voltage command transition means inputs a d-axis subtracter that subtracts the first voltage command Vd1 from the second voltage command Vd2, and inputs the output of the d-axis subtractor to obtain the first-order lag characteristic of the secondary time constant. D-axis primary delay transmission means for output, d-axis adder for adding the output of the d-axis primary delay transmission means and the first voltage command Vd1, and set after the time when the free-run speed is detected by the speed detection means. A d-axis voltage command switch that outputs the d-axis voltage command Vd to the power converter by switching from the first voltage command Vd1 so far to the output of the d-axis adder at a predetermined switching time, a second voltage command Q-axis subtractor for subtracting the first voltage command Vq1 from Vq2, q-axis primary delay transmission means for inputting the output of the q-axis subtractor and outputting the first-order lag characteristic of the second-order time constant, and this q-axis primary The output of the delay transmission means and the first voltage command Vq1 Q-axis adder to be added, and q-axis voltage command switching to output the q-axis voltage command Vq to the power converter by switching from the first voltage command Vq1 so far to the output of the q-axis adder at a predetermined switching time Since the device is provided, the transition process from the first voltage command to the second voltage command is quickly performed on the rotating biaxial coordinates.

  The second voltage command calculation means outputs a second voltage amplitude command V2 as a second voltage command based on the output of the speed detection means and a predetermined voltage / frequency (V / f) pattern. Since the voltage amplitude command calculation means is used, the second voltage amplitude command, which is the target value for the voltage command transition, can be obtained easily and reliably.

  In addition, a first voltage amplitude command calculating unit that calculates the voltage amplitude of the first voltage command and outputs the first voltage command as the first voltage amplitude command V1 is provided. A subtractor for subtracting the voltage amplitude command V1 of the first order, a first order lag transmission means for inputting the output of the subtractor and outputting a first order lag characteristic of the second order time constant, an output of the first order lag transmission means and the first voltage amplitude An adder for adding the command V1 and an output of the adder from the first voltage amplitude command V1 so far at a predetermined switching time set after the time when the free-run speed is detected by the speed detection means. Since the voltage command switching device for outputting the voltage amplitude command V to the power converter is provided, the transition process from the first voltage amplitude command to the second voltage amplitude command is quickly performed.

  In addition, when the induction machine is controlled based on a predetermined speed command, a subtractor that subtracts the free-run speed from the predetermined speed command, and the output of this subtractor is input to output the first-order lag characteristic of the secondary time constant. Set after the time when the voltage command to the power converter is shifted to the second voltage command by the voltage command shifting means. Since there is provided a speed command switching means equipped with a speed command switch that outputs the speed command by switching from the free run speed up to that point to the output of the adder at the predetermined switching time, the change from the free run speed to the speed command is provided. Transition is made promptly.

It is a figure which shows the structure of the power converter device by Embodiment 1 of this invention. It is a figure which shows the internal structure of the speed detection means 9 of FIG. It is a figure which shows the internal structure of the current control means 16 of FIG. It is a figure which shows the internal structure of the switching condition setting means 8 of FIG. It is a figure which shows the relationship between a starting signal and a switching condition signal. It is a figure which shows the internal structure of the 2nd voltage command calculating means 6 of FIG. It is a figure which shows the internal structure of the voltage command switching means 4 of FIG. It is a figure which shows the operation | movement waveform in Embodiment 1 of this invention. It is a figure which shows the equivalent circuit per phase of the induction machine. It is a figure which shows the equivalent circuit per phase of the induction machine 1 in case of slip = 0. It is a figure which shows the operation | movement waveform by the simulation in Embodiment 1 of this invention. It is a figure which shows the internal structure of the angular frequency generation means 29 of FIG. It is a figure which shows the structure of the power converter device by Embodiment 2 of this invention. It is a figure which shows the internal structure of the 2nd voltage amplitude command calculating means 24 of FIG. It is a figure which shows the internal structure of the voltage amplitude command switching means 22 of FIG. It is a figure which shows the internal structure of the three-phase voltage command calculating means 23 of FIG.

Explanation of symbols

1 induction machine, 2 power converter, 3a, 3b, 3c current detection means,
4 voltage command switching means, 5 first voltage command calculating means, 6 second voltage command calculating means,
7 phase calculation means, 8 switching condition setting means, 9 speed detection means,
10 three-phase / dq axis conversion means, 11, 11d, 11q, 31 first order lag transmission means,
12, 12d, 12q adder, 13, 13d, 13q switch,
14, 14d, 14q subtractor, 15 dq axis / three-phase conversion means, 16 current control means,
17 resistance gain, 18 integrator, 19 divider, 20 multiplier,
21, 27 V / f pattern, 22 voltage amplitude command switching means,
23 three-phase voltage command calculation means, 24 second voltage amplitude command calculation means,
25 first voltage amplitude command calculating means, 26 three-phase sine wave generating means,
28 first voltage command calculation means selection time setting means, 29 angular frequency generation means,
30 Voltage command transition time setting means.

Claims (10)

A power converter for driving the induction machine by outputting a voltage based on a predetermined voltage command, wherein the power converter stops outputting and the power converter is in a free-running state; In the power converter that restarts and returns to the driving state,
Speed detecting means for detecting a free-run speed, which is the speed of the induction machine in a free-run state on the condition that no torque is generated in the induction machine based on the start command, and the free-running based on a predetermined operation control characteristic of the induction machine Second voltage command calculation means for calculating a second voltage command set in accordance with the run speed, and restarting the power converter, the voltage command to the power converter is transferred to the free by the speed detection means. Means for controlling transition from the first voltage command, which is a voltage command to the power converter at the time when the run speed is detected, to the second voltage command, wherein the transition of the voltage command is determined by the free run. A power converter comprising voltage command transition means for performing first-order lag transmission control of a second-order time constant determined by a circuit constant of the induction machine in a state. The speed detection means is speed calculation means for restarting the power converter under a condition that does not generate torque in the induction machine based on the start command, and detecting the free run speed from its operation characteristics by calculation,
2. The voltage command transition means, wherein the first voltage command is a voltage command to the power converter when the free-run speed is detected by the speed calculation means. Power conversion device. Phase calculating means for calculating a phase θ of rotating biaxial coordinates (dq axes) based on the output of the speed detecting means, and a three-phase current detection value of the induction machine based on the phase θ, rotating biaxial coordinates (d -Q axis) d-axis current id, three-phase / dq-axis conversion means for converting to q-axis current iq, and d-axis current command id ^{* in which the} d-axis current id and q-axis current iq are set to predetermined values, respectively ^. And a first voltage command calculation means for outputting the first voltage commands Vd1 and Vq1 of the rotating biaxial coordinates (dq axes) so as to follow the q-axis current command iq ^* set to zero. The power converter according to claim 2 characterized by things. The speed detecting means calculates a magnetic flux amplitude φd based on a value obtained by subtracting a d-axis resistance voltage drop due to the d-axis current id from the first voltage command Vd1, and the q-axis is calculated from the first voltage command Vq1. 4. The power converter according to claim 3, wherein the free-run speed is calculated by dividing a value obtained by subtracting a q-axis resistance voltage drop caused by a current iq by the magnetic flux amplitude φd. The speed detection means is a speed detector that directly detects the speed of the induction machine in the free-run state,
2. The power converter according to claim 1, wherein the voltage command transition means sets the first voltage command to zero. The second voltage command calculation means has a predetermined value of Vd2 of the rotating biaxial coordinates (dq axes) that rotate in synchronization with the output from the speed detection means and the output of the speed detection means. 6. The power converter according to claim 1, wherein Vq <b> 2 based on a voltage / frequency (V / f) pattern is output as the second voltage command. 7. The voltage command transition means inputs a d-axis subtractor for subtracting the first voltage command Vd1 from the second voltage command Vd2, and inputs the output of the d-axis subtractor to input a first-order delay of the second-order time constant. The free-run speed is detected by the d-axis primary delay transmission means for outputting the characteristics, the d-axis adder for adding the output of the d-axis primary delay transmission means and the first voltage command Vd1, and the speed detection means. D-axis voltage command for switching from the first voltage command Vd1 up to that point to the output of the d-axis adder and outputting the d-axis voltage command Vd to the power converter at a predetermined switching time set after the time A switch, a q-axis subtractor that subtracts the first voltage command Vq1 from the second voltage command Vq2, and an output of the q-axis subtractor is input to output a first-order lag characteristic of the second-order time constant. q-axis primary delay transmission means, this q-axis A q-axis adder for adding the output of the next delay transmission means and the first voltage command Vq1, and switching from the first voltage command Vq1 so far to the output of the q-axis adder at the predetermined switching time. The power converter according to claim 6, further comprising a q-axis voltage command switching unit that outputs a q-axis voltage command Vq to the power converter. The second voltage command calculation means outputs a second voltage amplitude command V2 as the second voltage command based on the output of the speed detection means and a predetermined voltage / frequency (V / f) pattern. 6. The power conversion device according to claim 1, wherein the voltage amplitude command calculation means is used. A first voltage amplitude command calculating means for calculating the voltage amplitude of the first voltage command and outputting it as the first voltage amplitude command V1;
The voltage command transition means is a subtracter that subtracts the first voltage amplitude command V1 from the second voltage amplitude command V2, and inputs the output of the subtractor to obtain the first-order lag characteristic of the secondary time constant. The first-order lag transmission means for outputting, the adder for adding the output of the first-order lag transmission means and the first voltage amplitude command V1, and the time point when the free run speed is detected by the speed detection means are set. A voltage command switch that outputs the voltage amplitude command V to the power converter by switching from the first voltage amplitude command V1 so far to the output of the adder at a predetermined switching time is provided. The power conversion device according to claim 8. When the induction machine is controlled based on a predetermined speed command,
A subtractor for subtracting the free-run speed from the predetermined speed command, a first-order lag transmission means for inputting the output of the subtractor and outputting a first-order lag characteristic of the second-order time constant, and an output of the first-order lag transmission means And an adder for adding the free-run speed, and until a predetermined switching time set after the time when the voltage command to the power converter is shifted to the second voltage command by the voltage command shifting means. 10. A speed command shift means provided with a speed command switching device for switching the free run speed to the output of the adder and outputting the speed command is provided. Power conversion device.

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