JP4667741B2 - Induction motor control device - Google Patents

Description

  The present invention relates to a control device for driving induction motors such as trains, machine tools, fans, and pumps, and in particular, stable from a state where power supply to a power converter is stopped and the induction motor is free-running. This relates to a control device that is restarted.

  Conventionally, a residual magnetic flux detection circuit that detects a line voltage generated by the residual magnetic flux of the motor when power supply is stopped and outputs a pulse signal corresponding to the positive / negative of the line voltage, and a voltage that determines the output of the inverter Command, output frequency command, storage means for storing the phase rotation direction, and timer for managing the power supply stop time, the speed signal is obtained from the pulse signal obtained from the positive and negative of the line voltage, the speed signal and power supply stop It is shown that the residual voltage magnitude is estimated and acquired from the period and the voltage command value at the time of power supply stop, and the initial voltage value at restart is based on the estimated voltage magnitude, frequency, and phase angle. (See, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 1-194492 (FIG. 1)

  However, the technique disclosed in Patent Document 1 detects the residual voltage during the power supply suspension period to restart the inverter from the free-run state, and applies the same voltage as the phase, frequency, and amplitude of the residual voltage. Rebooting has been shown, which requires a means for detecting the residual voltage, which has hindered cost reduction. On the other hand, if the restart is performed after a period in which the residual magnetic flux is sufficiently attenuated, it is possible to restart with the overcurrent suppressed, but in this case, the residual magnetic flux decay period must be set from the time when the power supply is stopped. There is a problem that it is necessary to provide a restriction on the restart control.

  The present invention has been made to solve the above-described problems, and does not provide voltage detection means, does not depend on the length of the power suspension period, and does not generate an excessive current or torque shock. It is another object of the present invention to provide a control device for an induction motor that stably controls restart of an inverter.

The control apparatus for an induction motor according to the present invention comprises power conversion means, speed detection means, voltage command value calculation means, magnetic flux command value calculation means, magnetic flux command value change rate limiter, and torque command value calculation means. Is for supplying power to the induction motor, the speed detecting means is for detecting the rotational speed of the induction motor, and the magnetic flux command value calculating means is for calculating a desired magnetic flux command value for controlling the induction motor. The torque command value calculating means outputs a desired torque command value for controlling the induction motor to the voltage command value calculating means, and the voltage command value calculating means The means calculates a magnetic flux current command value and a torque current command value from the magnetic flux command value and the torque command value, and supplies power to the power conversion means based on the magnetic flux current command value and the torque current command value. The command value is calculated and output. During the period when the power conversion means stops operating and the power supply to the induction motor is stopped, the magnetic flux command value calculation means determines the rotation speed, circuit constants, and power supply stoppage of the induction motor. Based on the magnetic flux command value , the calculation of the magnetic flux command value at the time of resuming power supply is continued and output to the magnetic flux command value change rate limiter. The magnetic flux command value change rate limiter When the power supply to the induction motor is resumed, the flux command value change rate limiter controls the rate of change of the flux command value and outputs it to the voltage command value calculation means. The command value calculation means continuously executes the calculation of the reference phase angle of the voltage command value based on the torque command value and the rotation speed output by the speed detection means even when the operation of the power conversion means is stopped. Magnetic flux command value and Obtain a voltage command value at the time of resumption of power supply by calculating based on the quasi phase angle, and set this voltage command value as an initial value of the voltage command value to the power conversion means at the time of resumption of power supply to the induction motor, Thereafter, an output is made to increase the amplitude of the voltage command value to a desired value.

In the control device for an induction motor according to the present invention, the voltage command value calculation means calculates a magnetic flux component current command value and a torque component current command value from the magnetic flux command value and the torque command value, and the magnetic flux component current command value and the torque component current command. The voltage command value to the power conversion means is calculated and output based on the value, and during the period when power supply to the induction motor is stopped, the rotation speed, circuit constants, and magnetic flux command value when power supply is stopped Based on the above, the calculation of the magnetic flux command value at the time of resuming power supply is continued and output to the magnetic flux command value change rate limiter. The magnetic flux command value change rate limiter When the power supply to the induction motor is resumed, the magnetic flux command value change rate limiter controls the change rate of the magnetic flux command value and outputs it to the voltage command value computing means. Is power conversion Even when the stage is stopped, the reference phase angle of the voltage command value is calculated based on the torque command value and the rotation speed output by the speed detection means, and is calculated based on the magnetic flux command value and the reference phase angle when power supply is resumed. Since the voltage command value at the time of resumption of power supply is acquired, this value is set as the initial value of the voltage command value to the power conversion means at the time of resumption of power supply, and then the amplitude of the voltage command value is increased to a desired value. Without using the voltage detection means, it is possible to suppress the overcurrent and the torque shock and stably restart regardless of the length of the power supply stop period (the magnitude of the residual magnetic flux).

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a control device 100 for an induction motor according to Embodiment 1, in which an induction motor 1, a power conversion unit 2, a voltage command value calculation unit 3, a magnetic flux command value calculation unit 4, a speed detection unit 5, It comprises a sequence management means 6 and a torque command value calculation means 7.
First, the torque control method of the induction motor 1 will be described. The magnetic flux command value calculation means 4 and the torque command value calculation means 7 output the desired magnetic flux command value Φr_ref and torque command value τ_ref for controlling the induction motor 1 to the voltage command value calculation means 3. Further, the speed detection means 5 detects the rotational speed wr of the induction motor 1, and this is also output to the voltage command value calculation means 3. Hereinafter, in the embodiment of the present invention, the electrical angular rotational speed obtained by multiplying the mechanical angular rotational speed by the number of pole pairs of the induction motor is expressed as a rotational speed wr.
Before describing the control method of the induction motor 1, that is, the operation of the voltage command value calculation means 3, the notations used in the description of the present invention are summarized below.
Notation of state quantity of induction motor dq axis: orthogonal biaxial coordinate system rotating in synchronization with magnetic flux vector of induction motor Φd, Φq: d-axis magnetic flux and q-axis magnetic flux (usually, Φq to match d-axis with magnetic flux vector = 0)
id, iq: d-axis current and q-axis current vd, vq: d-axis voltage and q-axis voltage vu, vv, vw: u-phase voltage, v-phase voltage, w-phase voltage in three phases wr: electrical angular rotation speed w: Rotational frequency of magnetic flux vector ws: slip (w-wr)
θ: d-axis phase angle from the fixed axis (reference phase angle for vector control)
Notation of induction machine constant Rs: Primary resistance value Ls: Primary inductance value Rr: Secondary resistance value Lr: Secondary inductance value M: Mutual inductance value σ: Leakage coefficient (1-M ² / Ls / Lr)

The voltage command value calculation means 3 calculates a command value of a voltage to be output to the induction motor 1 based on the magnetic flux command value Φr_ref, the torque command value τ_ref, and the rotation speed wr, and outputs it to the power conversion means 2. As an example, calculation means when using so-called vector control will be described below.
The slip frequency command ws_ref is calculated from the magnetic flux command value Φr_ref and the torque command value τ_ref, and at the same time, the dq coordinate system that rotates in synchronism with the magnetic flux of the induction motor 1 is used to regard the voltage and current as a direct current, and the magnetic flux current command The value ids_ref and the torque current command value iqs_ref are calculated once. A d-axis voltage command value vd_ref and a q-axis voltage command value vq_ref are calculated based on the magnetic flux current command value ids_ref and the torque current command value iqs_ref, and further converted into an amplitude value and a phase angle of the voltage command value. In this case, vd_ref and vq_ref are coordinate-converted into three-phase AC voltage command values Vu_ref, Vv_ref, and Vw_ref on the stator coordinates, thereby calculating a three-phase AC voltage command value.
The three-phase AC voltage command value obtained in this way is output to the power conversion means 2. Specifically, the power conversion means 2 performs PWM modulation based on the voltage command value, outputs a gate drive signal, and performs a switching operation of a so-called main circuit of the inverter based on the gate signal. Is output to the induction motor 1 to drive it.

  Next, the power supply stop and restart sequence of the induction motor 1 will be described. The sequence management means 6 is based on a command from a higher-level controller (not shown), for example, an operation stop command and an operation restart command issued from a means for monitoring power failure and power recovery of the power conversion means 2. Thus, a gate-off signal and a gate-on signal are output to the power converter 2, the magnetic flux command value calculator 4, and the torque command value calculator 7. By the way, in the electric railway application, in order to suppress power loss due to the switching operation of the main circuit itself, the period during which no torque is generated is a period in which the power supply operation is suspended by actively shutting off the gate. Operation is frequent and important.

FIG. 2 schematically shows the gate-off signal output from the sequence management means 6, and the timing of the gate-on signal and each command value. First, a gate-off sequence for stopping power supply will be described.
When a gate-off signal is output from the sequence management means 6 during normal operation, the power conversion means 2 shuts off the gate, and the supply of current to the induction motor 1 stops accordingly. However, as already described, magnetic flux remains in the induction motor 1 and a residual voltage resulting from this is generated between the terminals.
Specifically, the secondary magnetic flux (d-axis component) Φdr as seen in the dq-axis coordinates behaves as shown in the following formula 1 (usually, since the secondary magnetic flux vector is adopted for the d-axis, the q-axis component Φqr is 0. is there).

However, (PHI) dr_off shows the magnitude | size of the magnetic flux at the time of gate interruption | blocking, and s is a Laplace operator. Other constants are as described above.
Equation 1 can be derived from the following equations 2 and 3, which show the characteristics of the secondary circuit of the induction motor, since the d-axis current id and the q-axis current iq become 0 from the moment of gate interruption.

  In the first embodiment, as shown in FIG. 2, the magnetic flux command value calculation means 4 calculates a restart magnetic flux command value Φdr_ref_on that coincides with the residual magnetic flux shown in Equation 1 while the gate is shut off. Here, Φdr_ref_on is calculated by the following Expression 4 based on Expression 1.

Here, Φdr_off is a magnetic flux command value at the time of gate interruption, and Rr ^* and Lr ^* are set values of the secondary resistance Rr and the secondary inductance Lr preset in the magnetic flux command value calculation means 4.
Further, in order to maintain the reference coordinate axis of the vector control even while the gate is shut off, the calculation of the angle θ formed by the d axis from the stator coordinate reference axis (for example, the u phase of the three phases of uvw) is continued. However, the difference between the actual slip, that is, the rotational frequency of the magnetic flux and the electrical angular rotational frequency of the rotor is 0 during the gate interruption so that there is no error between the actual d-axis and the d-axis managed by the voltage control means. Taking this into consideration, the slip command ws_ref is set to 0, and θ is calculated by the following equation 5. Needless to say, even if the torque command value calculating means outputs the torque command value τ_ref = 0, it is possible to indirectly calculate the slip command ws_ref = 0.

  Then, the calculation in the voltage command value calculation means 3 is continued using the restarting magnetic flux command value Φdr_ref_on, the d-axis phase angle θ, and the torque command τ_ref = 0 obtained by continuing the calculation even while the gate is shut off. Then, a voltage command value equal to the induced voltage caused by the residual magnetic flux can be calculated.

Next, a sequence when the gate is turned on to resume power supply will be described.
When a gate-on signal is output from the sequence management means 6 during the gate cutoff period during which the power supply is suspended, the magnetic flux control and torque control of the induction motor are resumed. In the magnetic flux command value calculation means 4, the magnetic flux command value Φdr_ref is raised to a desired target value. As an initial value at that time, the value at the end of the gate cutoff period of Φdr_ref_on calculated during gate cutoff is adopted. The calculation output of the value Φdr_ref is started. Similarly, with respect to the d-axis phase angle θ obtained by continuing the calculation while the gate is cut off, the integration operation of the above equation 5 is continued without resetting the same, and the slip command ws_ref corresponding to the rising edge of the torque command τ_ref is set. It is assumed that the normal vector control phase angle is calculated while reflecting. Thus, by calculating the voltage command value in the voltage command calculation means 3 based on the magnetic flux command value Φdr_ref and the d-axis phase angle θ when the power supply is resumed, the initial voltage value equal to the induced voltage value during gate shut-off can be smoothly obtained. It is possible to shift to voltage command value calculation for restart. That is, by restarting the PWM modulation operation of the power conversion means 2 in synchronization with the gate-on signal in this state, the induction motor 1 can be restarted without generating a current shock and a torque shock.

As described above, as shown in FIGS. 1 and 2, in the first embodiment, during the period when the power supply is stopped, the rotation speed output by the speed detection means 5, the magnetic flux command value when the power conversion is stopped, By obtaining the operation restarting magnetic flux command value as vector information by calculation based on the circuit constants of the induction motor 1, it is possible to perform an operation for making the residual magnetic flux in the induction motor 1 coincide with the operation restarting magnetic flux command value. For,
When resuming the operation of the power conversion means 2 and resuming the power supply to the induction motor 1, the operation resumption magnetic flux command value is set as the initial value of the magnetic flux command value, and then the magnitude of the magnetic flux command value is desired. By increasing the value to the value, it becomes possible to perform the magnetic flux rise control in consideration of the residual magnetic flux, and stable current control and torque control can be performed without using a voltage detector regardless of the power supply stop period.

Embodiment 2. FIG.
Next, the second embodiment will be described with reference to the drawings.
FIG. 3 shows a control device 100 for an induction motor according to a second embodiment, which is obtained by adding a saturation characteristic table 40 to the configuration of the first embodiment shown in FIG.
The inductance value of the induction motor 1 varies depending on the magnitude of the magnetic flux. Specifically, the relationship between the d-axis current ids, which is a magnetic flux component current, and the secondary magnetic flux Φdr is not linear, and Φdr has a characteristic that saturates as ids increases, and the larger ids and Φdr, The mutual inductance M, the primary side inductance Ls, and the secondary side inductance Lr of the induction motor 1 have characteristics that become small.
Due to the above, Rr / Lr, which is a constant related to the first-order lag characteristic in Equation 1, changes according to the magnitude of the secondary magnetic flux Φdr. For example, when the secondary inductance value Lr_100 in the rated magnetic flux is set as a fixed value as the secondary inductance value Lr ^* in the magnetic flux command value calculation means 4, the actual magnetic flux decreases with the decrease in the magnitude of the magnetic flux during the gate interruption period. Since the secondary inductance Lr increases relative to Lr_100 and Lr ^* , there is a strict difference between the expression 1 that represents the true magnetic flux and the output result of the expression 4 that is the calculation content of the magnetic flux command value calculation means 4. The difference as shown in FIG. If the magnetic flux startup sequence is entered using the calculation result of Φdr_ref_on of Expression 4, a current or torque shock is generated due to a control error caused by the difference between the operation resumption magnetic flux command value and the actual magnetic flux.
Therefore, in the second embodiment, a saturation characteristic table 40 in which a saturation characteristic between the actual magnetic flux magnitude Φdr and the actual secondary inductance Lr is recorded is provided, and the magnitude of Φdr_ref changing every moment and the saturation characteristic table are provided. 40, the secondary inductance set value Lr ^* is obtained and reflected as Lr ^* during the calculation of Expression 4 in the magnetic flux command value calculation means 4. By doing so, Φdr in Equation 1 describing the actual behavior of the magnetic flux and the operation resumption magnetic flux command value Φdr_ref_on in the magnetic flux command value calculation means 4 coincide with each other with high accuracy. It becomes possible to further suppress the current shock and torque shock at the time.

As described above, as shown in FIG. 3, the saturation characteristic table 40 in which the relationship between the magnetic flux and the inductance of the induction motor 1 is recorded is provided for the configuration of FIG. 1 and reflected in the calculation of the operation resumption magnetic flux command value Φdr_ref_on. In addition to the effects of the first embodiment,
Since it is possible to calculate a flux command value for resuming operation that more accurately matches the behavior of the actual residual magnetic flux, the magnetic flux startup control considering the residual magnetic flux becomes smoother, and the current shock and torque shock are further increased. The effect which can be reduced is acquired.

In the above, the method of avoiding the influence on the calculation of Equation 4 by the secondary inductance fluctuating due to the saturation characteristic among the induction motor constants has been described. Similarly, it is caused by the temperature change. If the value of the secondary resistance Rr that fluctuates in this way is detected by the resistance value detection means added to the induction motor 1, and this is reflected in Rr ^* of equation 4, the operation resumption magnetic flux command value Φdr_ref_on and the actual magnetic flux ΦRd are Needless to say, they match with high accuracy. The resistance value detecting means is not shown.
As the secondary resistance value detecting means, the temperature of the rotor of the induction motor 1 is measured to obtain the actual Rr from a table in which the temperature characteristic of the secondary resistance R2 is recorded, or Rr without using a thermometer. Is already known, and by combining these, the calculation accuracy of the operation resumption magnetic flux command value Φdr_ref_on of Equation 4 can be improved.

Embodiment 3 FIG.
Next, Embodiment 3 will be described with reference to the drawings.
FIG. 5 shows a control device 100 for an induction motor according to a third embodiment, in which a magnetic flux command value change rate limiter 41 is added to the configuration of the first embodiment shown in FIG. As described with reference to FIG. 2, when the gate is turned on, the magnetic flux command value Φdr_ref is increased to the target value using the magnetic flux command value Φdr_ref_on for restarting operation as an initial value, but the magnetic flux command value change rate limiter 41 Output to the voltage command value calculation means 3. It will be described below that the current shock and torque shock that occur during the period from when the gate is turned on until the magnetic flux command value Φdr_ref reaches the target value can be further reduced.
Of Expressions 2 and 3 indicating the characteristics of the secondary side circuit of the induction motor, Expression 6 below is a result of the shift operation performed on Expression 2 regarding the magnitude of the secondary magnetic flux Φdr.

According to Equation 6, it can be said that the larger the change rate of the magnetic flux, the larger the d-axis current ids is generated.
Next, the voltage equation of the primary side circuit of the induction motor 1 is as the following Expression 7. Similar to Equations 2 and 3, it is a notation on rotational coordinates with the secondary magnetic flux vector as the d-axis.

The state quantity and the constant notation of the induction motor 1 are as already described.
When attention is paid to the q-axis equation, it can be seen that (w · σLs · ids) exists as an interference term from the d-axis. That is, when the change rate of the magnetic flux is large, it can be said that a large d-axis current ids is generated according to Equation 6 and an interference voltage (w · σLs · ids) with respect to the q-axis voltage is generated. In the voltage command value calculation means 3, if the interference voltage is accurately reflected in the command value, that is, the d-axis phase angle θ is accurately controlled and the non-interference control can be performed accurately, the interference voltage becomes a current transient response. Although there is no disturbance, in practice, θ becomes a value that is transiently deviated from the actual secondary magnetic flux vector, or the set value of the leakage inductance in the voltage command value calculation means has an error relative to the actual σLs. It is difficult to make it completely non-interfering by having it. As a result, when the interference voltage (w · σLs · ids) with respect to the q-axis voltage is abruptly generated as a disturbance, a q-axis current is transiently generated, and a transient torque is generated by the product with the magnetic flux. It will be.

From the above, if the magnetic flux is suddenly changed, a transiently large d-axis current is generated, which generates an interference voltage as a disturbance to the q-axis, which also causes a transient q-axis current control, and thus transient. It can be said that a torque control error also occurs. In other words, if the change in magnetic flux is gradual, the above transient current and transient torque are unlikely to occur.
Therefore, a magnetic flux command value change rate limiter 41 is provided at the output of the magnetic flux command value generating means 4 to limit the change rate of the magnetic flux command value. As a result, it is possible to reduce current shock and torque shock that occur when the magnetic flux command value is increased to the target value after gate-on.
As described above, as shown in FIG. 5, the magnetic flux command value change rate limiter 41 for limiting the change rate of the magnetic flux command value is provided in the configuration of FIG. In addition to the effects in
Since it is possible to suppress the d-axis current ids from becoming transiently large, and to suppress the generation of transient disturbance voltage to the q-axis, the transient q-axis current control error, and the torque control error at the same time, Current shock and torque shock during restart can be further reduced.

Embodiment 4 FIG.
Next, a fourth embodiment will be described with reference to the drawings.
FIG. 6 shows an induction motor control apparatus 100 according to the fourth embodiment, and the components 1 to 7 are the same as those in the first embodiment, and the description thereof is omitted. The fourth embodiment is characterized in that, in the configuration of the control device provided with the magnetic flux estimation means 9, the magnetic flux control is performed when the gate is turned on based on the magnetic flux estimation value that is the output. The operation will be described below.
First, the current detection means 8 detects the current flowing through the primary circuit of the induction motor 1. When the current detection means 8 is installed in this way, a so-called current loop is formed in which the detected current is fed back to the voltage command value calculation means 3 and the voltage command value is adjusted based on the difference from the current command value. It is well known as a general technique in motor control that the current control response and control accuracy are improved, and consequently the torque control accuracy is improved.
The magnetic flux estimation means 9 is based on the rotation speed of the induction motor 1 obtained by the speed detection means 5, the current value obtained by the current detection means 8, and the voltage command value that is the output of the voltage command value calculation means 3. 1 magnetic flux is estimated. An example of the configuration of the magnetic flux estimation means 9 is shown, for example, in the Institute of Electrical Engineers, Industrial Application Division, Vol. 121, No. 8 (2001) Kanehara et al., “Vector Control Method of Induction Motor Using an Optimal Observer Robust to Resistance Variation”. Yes. The arithmetic expression is cited below.

  The phase angle information of the secondary magnetic flux estimated value is output as the d-axis phase angle θ to the voltage command value calculation means 3 and used for coordinate conversion. In the above document, the rotational frequency w of the secondary magnetic flux is calculated as follows, and θ is calculated using it.

The estimated value of the secondary magnetic flux is output to the magnetic flux command value calculating means 4 and used for controlling the magnetic flux.
Here, the operation of the magnetic flux estimation means 9 accompanying gate-off and gate-on will be described.
During a period in which power is supplied to the power conversion means 2 and the induction motor 1, that is, a period in which a voltage is output to the induction motor 1 by a desired PWM operation, the primary terminal voltage of the induction motor 1 is almost equal to the voltage command. It is equal to the output of the value calculation means 3. Therefore, by substituting the voltage command value as the primary terminal voltage signal necessary for the magnetic flux estimation means 9, it is possible to perform magnetic flux estimation while omitting the hardware for detecting the voltage and suppressing costs. is there. Of course, since not only the magnitude information but also the phase angle information of the secondary magnetic flux can be estimated, the d-axis phase angle θ can be calculated, and a coordinate conversion operation for vector control is possible.
On the other hand, the primary terminal voltage of the induction motor 1 and the output of the voltage command value calculation means 3 do not necessarily match during the period when power is not supplied to the power conversion means 2 and the induction motor 1 and during the gate cutoff period. Therefore, if the method of substituting the voltage command value as described above is used for the input of the magnetic flux estimation means 9, the accuracy of the magnetic flux estimation value that is the output of the magnetic flux estimation means 9 will be significantly reduced. Therefore, during the gate cut-off period, the magnetic flux estimation calculation method that does not use the primary terminal voltage is switched. In the example in the above document, by substituting the feedback gain H with H_off in Equation 9 below, the estimation calculation of the secondary magnetic fluxes Φdr and Φqr becomes equivalent to Equations 2 and 3 used in the description of Embodiment 1. It is possible to adopt a magnetic flux estimation calculation format that does not use a voltage value.

Thus, by switching the feedback gain matrix H to H_off for the gate interruption period and continuing the magnetic flux estimation calculation by the magnetic flux observer of the above formulas 9 and 10, the secondary magnetic flux during the gate interruption period, so-called residual magnetic flux, is estimated. This is output to the magnetic flux command value calculation means 4 and set as a power supply resumption magnetic flux command value. Further, since not only the information on the magnitude of the magnetic flux but also the information on the phase angle of the secondary magnetic flux can be estimated, it is possible to calculate the d-axis phase angle θ during the interruption period.
Note that during the gate cutoff period, it is almost equivalent to opening the terminal of the induction motor 1, and the primary currents ids and iqs are both 0 in principle. After all, the calculation of Expressions 9 and 10 during the gate cutoff period using H_off of Expression 12 is based only on the estimated magnetic flux at the gate-off time, the rotational speed wr, and the circuit constants of the induction machine. Therefore, the same magnetic flux estimation calculation can be performed even when switching to a simple arithmetic expression that omits the calculation of adding zero, and is implemented in the magnetic flux estimation means 9 in consideration of the balance with the simplification of the sequence by omitting the switching items. It ’s fine.
As described above, the secondary magnetic flux estimation calculation and the d-axis phase angle θ can be calculated regardless of the power supply period and the gate cutoff period. Accordingly, when the gate is turned on, if the estimated magnetic flux value Φdr at that time is set as the initial value of Φdr_ref of the magnetic flux command value calculation means 4 as the operation resumption magnetic flux command value, the voltage command value calculation means 3 is a voltage that takes into account the residual magnetic flux. The command value can be output, and if the operation of the power conversion means 2 is resumed from this state, the operation of the induction motor 1 and the power conversion means 2 can be stably resumed without generating a current shock and a torque shock. Thereafter, if the magnetic flux command value Φdr_ref is increased to a desired target value, it is possible to shift to a desired operation state.

As described above, as shown in FIG. 6 of the fourth embodiment, the estimated magnetic flux when the power conversion means 2 is stopped, the rotational speed output by the speed detection means 5, and the induction motor during the period when the power supply is stopped. Since the operation restarting magnetic flux command value as vector information is obtained by the calculation based on the circuit constant of 1, the calculation of matching the residual magnetic flux in the induction motor 1 with the operation restarting magnetic flux command value becomes possible.
When resuming the operation of the power conversion means 2 and resuming the power supply to the induction motor 1, the operation resumption magnetic flux command value is set as the initial value of the magnetic flux command value, and then the magnitude of the magnetic flux command value is desired. By increasing the value up to this value, it becomes possible to control the rise of magnetic flux in consideration of the residual magnetic flux, and it is possible to carry out stable current control and torque control without using a voltage detector regardless of the power supply stop period. can get.

  As described above, the control apparatus for induction motors according to the first to fourth embodiments of the present invention can be applied to induction motors used for driving trains, machine tools, fans, pumps, and the like.

It is a block diagram which shows the control apparatus of the induction motor of Embodiment 1 of this invention. It is a figure which shows typically the signal timing of Embodiment 1 of this invention. It is a block diagram which shows the control apparatus of the induction motor of Embodiment 2 of this invention. It is a figure which shows typically the signal timing of Embodiment 2 of this invention. It is a block diagram which shows the control apparatus of the induction motor of Embodiment 3 of this invention. It is a block diagram which shows the control apparatus of the induction motor of Embodiment 4 of this invention.

Explanation of symbols

1 induction motor, 2 power conversion means, 3 voltage command value calculation means,
4 magnetic flux command value calculating means, 5 speed detecting means, 7 torque command value calculating means,
8 current detection means, 9 magnetic flux estimation means, 40 saturation characteristic table,
41 Magnetic flux command value change rate limiter, 100 Induction motor control device.

Claims (4)

A control device for an induction motor,
Power conversion means, speed detection means, voltage command value calculation means, magnetic flux command value calculation means, magnetic flux command value change rate limiter, torque command value calculation means,
The power conversion means supplies power to the induction motor, and the speed detection means detects a rotation speed of the induction motor,
The magnetic flux command value calculating means calculates a desired magnetic flux command value for controlling the induction motor, and outputs it to the voltage command value calculating means.
The torque command value calculation means outputs a desired torque command value for controlling the induction motor to the voltage command value calculation means,
The voltage command value calculating means calculates a magnetic flux current command value and a torque current command value from the magnetic flux command value and the torque command value, and based on the magnetic flux current command value and the torque current command value, Calculates and outputs the voltage command value to the power conversion means,
During the period in which the power conversion means stops operating and stops feeding the induction motor,
The magnetic flux command value calculation means continues the calculation of the magnetic flux command value at the time of resuming the power supply based on the rotational speed of the induction motor, the circuit constants, and the magnetic flux command value at the time of the power supply stop. Output,
The magnetic flux command value change rate limiter limits the rate of change of the magnetic flux command value when the power supply is resumed, which is output from the magnetic flux command value calculation means, and when the power supply to the induction motor is resumed, the magnetic flux command value change rate The limiter controls the rate of change of the magnetic flux command value and outputs it to the voltage command value calculating means,
The voltage command value calculation means continuously calculates a reference phase angle of the voltage command value based on the torque command value and the rotation speed output by the speed detection means even when the operation of the power conversion means is stopped. A voltage command value at the time of resuming power feeding is obtained by calculating based on the magnetic flux command value at the time of resuming power feeding and the reference phase angle, and the power at the time of resuming power feeding to the induction motor is obtained from this voltage command value. A control device for an induction motor, which is set as an initial value of a voltage command value to a conversion means and then outputs to increase the amplitude of the voltage command value to a desired value. In addition, the control device for the induction motor is provided with a saturation characteristic table attached to the magnetic flux command value calculation means, and the saturation characteristic table is a saturation characteristic between the magnetic flux and the inductance of the induction motor. Is recorded,
2. The induction motor control device according to claim 1, wherein when the magnetic flux command value calculation means calculates a magnetic flux command value when power supply is resumed, the saturation characteristic table is reflected in the calculation. In addition to the induction motor control device, a resistance value detection means is provided,
The resistance value detecting means estimates a resistance value associated with a temperature change of the secondary winding circuit and outputs the estimated resistance value to the magnetic flux command value calculating means. The magnetic flux command value calculating means feeds the estimated resistance value. The control apparatus for an induction motor according to claim 1 or 2, wherein a magnetic flux command value at the time of restart is reflected in a circuit constant at the time of calculation. A control device for an induction motor,
Power conversion means, speed detection means, current detection means, voltage command value calculation means, magnetic flux command value calculation means, magnetic flux estimation means and magnetic flux command value change rate limiter,
The power conversion means supplies power to the induction motor, and the speed detection means detects a rotation speed of the induction motor,
The current detection means detects a primary circuit current of the induction motor and feeds back to the voltage command value calculation means.
The magnetic flux command value calculating means calculates a desired magnetic flux command value for controlling the induction motor, and outputs it to the magnetic flux command value change rate limiter.
The voltage command value calculation means calculates a magnetic flux current command value and a torque current command value from the magnetic flux command value and the torque command value, and the electric power based on the magnetic flux current command value and the torque current command value. While calculating and outputting the voltage command value to the conversion means, the reference phase angle of the voltage command value is calculated,
The magnetic flux command value change rate limiter limits the rate of change of the magnetic flux command value when the power supply is resumed, which is output from the magnetic flux command value calculation means, and when the power supply to the induction motor is resumed, the magnetic flux command value change rate The limiter controls the rate of change of the magnetic flux command value and outputs it to the voltage command value calculating means, and the magnetic flux estimating means calculates the magnetic flux estimated value for controlling the induction motor, and the voltage command value calculating means And output to the magnetic flux command value calculation means,
During the period in which the power conversion means stops operating and stops feeding the induction motor,
The magnetic flux command value calculation means continues the calculation of the magnetic flux command value at the time of resuming the power supply based on the rotation speed of the induction motor, the circuit constant, and the estimated magnetic flux value at the time of power supply stop, and outputs it to the voltage command value calculation means And
The voltage command value calculation means continuously calculates a reference phase angle of the voltage command value based on the rotation speed output by the speed detection means even when the operation of the power conversion means is stopped, and resumes the power supply A voltage command value at the time of resuming power supply is obtained by calculating based on the magnetic flux command value at the time and the reference phase angle, and this voltage command value is a voltage command value to the power conversion means at the time of resuming power feeding of the induction motor. And the induction motor is restarted. After starting, the magnetic flux estimation means estimates the magnetic flux based on the rotational speed, the primary side circuit current, and the voltage command value output from the voltage command value calculation means. Is output to the voltage command value calculation means, and the voltage command value calculation means outputs a voltage command value calculated based on the estimated magnetic flux value and a reference phase angle to the power conversion means. Control device for an induction motor and outputs to increase the amplitude of the voltage command value to the trailing desired value.

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