JPH08237963A - Controller and control method for power converter - Google Patents

Abstract

PURPOSE: To suppress the increase of DC voltage by switching the function of a second power converter for converting the power required for the speed control and torque control of a load to the function for controlling the DC voltage upon occurrence of abnormality in a first power converter for converting AC voltage to DC voltage. CONSTITUTION: The inventive controller is different from a conventional one in that the DC voltage from a voltage detector 10 is fed to the controller (CD) 9A for normal system A and the controller CD9B for stand-by system B and when the power converter(PC) 2 side is abnormal, an abnormality signal is transmitted from a diagnostic section 28 to the controllers CD9A, CD9B for both systems. Similarly to a conventional controller, the CD9A (or CD9B) normally receives a speed signal and a current signal from a speed detector 6 and a current detector 7B and controls a PC4 of speed control function. Upon occurrence of an abnormal signal on the PC2 side, a diagnostic section 28 transmits an abnormality signal to the CD9A (or 9B). The CD9A (or 9B) makes a switching from speed control function to DC voltage control function and controls the PC4 to suppress the increase of DC voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method and an apparatus for a power conversion device which performs AC-DC-AC power conversion using a self-extinguishing element.

[0002]

2. Description of the Related Art A conventional power converter using a self-extinguishing element (PWM GTO converter) has a power supply 1, a first PWM power converter 2, a smoothing capacitor 3, as shown in FIG.
The second PWM power converter 4, the induction motor 5, the speed detection encoder 6, the current detector 7, the controller 8 for the first power converter 8, the normal A system 8A of the dual systems, the standby B system 8B. ,
Control device 9 of the second power converter, normal A system 9-1A and standby B system 9-1B of the dual system, DC voltage detector 10, and A system and B system of the first power converter Switching unit 26,
Diagnosis unit 2 for determining an abnormality of the A system and B system switching unit 27 of the second power converter, the control device regular A system 8A, and the standby B system 8B
8, a control unit regular A system 9-1A, and a standby B system 9-1B for diagnosing an abnormality. In this power conversion device, the first power converter and the second power converter are publicly known examples (Hitachi review VOL75, NO6, 1993-1993).
6, PP31-34), the first power converter side controls the power factor on the power supply side and the DC voltage is controlled to be constant, and the second power converter side generates the electric current of the electric motor. Torque and speed control is performed. That is, as shown in FIG. 4, the electric power controlled by the control device 9 (9-1A or 9-1B) of the second power converter and converted by the second power converter 4 (necessary for speed control of the electric motor). Corresponding power P _I or P _I ′, equal power P _O (= P _I ) or P _O ′ (= P _I ′) is applied to the controller 8 (8) of the first power converter.
-1A or 8-1B) is used to control the power by the first power converter 2. here,
P _I and P _O are electric power regenerated from the induction motor 5 to the power source 1, P _O
I ′ and P _O ′ represent electric power supplied from the power source 1 to the induction motor 5. However, in this conventional control method, as shown in FIG. 5, when the control device 8A in operation becomes abnormal, the first control
Pause power conversion of the power converter 4 (P _O = 0),
Meanwhile, the power P _I from the second power converter 4 continues to be converted, and the smoothing capacitor 3 is overcharged, resulting in an overvoltage. Therefore, a method is adopted in which the second power converter 4 is temporarily stopped, switched to the standby control device 8B, and then restarted. In this way, the conventional control method is
When an abnormality occurs, both power converters will be suspended. By the way, when both power converters are temporarily stopped, the DC voltage becomes a voltage due to the uncontrollable rectification action of both converters, and the excitation component current (reactive force) of the induction motor controlled by the second power converter 4 is controlled. Since the electric power component) is also stopped, the establishment of the magnetic flux of the electric motor is disrupted. Therefore, the conventional control method has a drawback that it takes time to perform a pre-start operation for establishing the DC voltage and establishing the magnetic flux of the electric motor when restarting after control switching.

[0003]

As described above, in the conventional control method, when an abnormality occurs on the side of the first power converter 2 for controlling the DC voltage, the second power converter 4 also receives the DC voltage. You have to stop to control the rise of. Therefore, even if the control devices 8 and 9 are configured as a dual system, both converters are temporarily stopped, and after switching, it is necessary to perform a starting operation such as establishment of a DC voltage and a magnetic flux of the induction motor, which causes a problem in operation continuity. there were. Further, when the DC voltage rises due to the abnormality of the first power converter 2, the second power converter 4 has only the function of stopping the overcharge power, so that the DC voltage rise is reduced. There is a problem that control, that is, overvoltage control cannot be performed. Even if the first power converter 2 does not become abnormal, if the load of the second power converter 4 suddenly changes, P _I > Po due to the power conversion delay of the first power converter 2. The smoothing capacitor 3 is overcharged and becomes overvoltage. Therefore, there is a problem that the capacity of the smoothing capacitor must be increased in order to reduce the overvoltage to a predetermined level or less.

An object of the present invention is, in a power converter having first and second power converters, a direct current due to an abnormality on the first power converter side, a switching of its control device, or a sudden change in load. An object of the present invention is to provide a control method and device for a power conversion device that is suitable for suppressing an increase in DC voltage when the voltage rises and continuing the operation of the load.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to provide a power conversion device comprising a first power converter and a second power converter, in which the first power converter for converting AC of the power supply into DC voltage is abnormal. In case of the above, by switching the second power exchanger that converts the power required for speed control and torque control of a load such as an electric motor to the function of controlling the DC voltage,
Achieved. In addition, when the control device of the first power converter is configured in a dual system and the switching from one control device to the other control device is required, the second power converter controls the DC voltage. It is achieved by switching to the voltage control function of the second power converter, switching the control device of the first power converter, and then restoring the control function of the second power converter. Further, when the converted DC voltage exceeds a predetermined value, the second power converter is switched to a voltage control function for controlling the DC voltage, and when the converted DC voltage becomes a predetermined value or less, the second It is achieved by restoring the control function of the power converter. Further, when the converted DC voltage becomes equal to or higher than a predetermined set voltage, a command for speed control is corrected by a deviation between the DC voltage and the set voltage as a control function of the control device of the second power converter. This is achieved by controlling the DC voltage based on this corrected command.

[0006]

According to the present invention, when the abnormality of the first power converter side or the switching of the control device is performed, the second power converter is operated by the function of controlling the voltage to suppress the rise of the DC voltage. Further, the fluctuation of the DC voltage caused by the sudden change of the load is suppressed within a predetermined value, and the capacity of the smoothing capacitor is greatly reduced.
Further, even if the control switching on the side of the first power converter occurs, the second power converter continuously controls the exciting current of the load to keep the magnetic flux constant and the DC voltage within a predetermined range. After the abnormal recovery due to the switching, the second power converter is returned to the original control and the operation of the load is continued.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a PWM power converter using a GTO element showing an embodiment of the present invention. 1 is the power supply,
2 is a first power converter, 3 is a smoothing capacitor, 4 is a second
Power converter, 5 is an induction motor, 6 is a speed detector (encoder) for detecting speed, 7A and 7B are first and second
Current detectors for respectively detecting the AC side currents of the power converters 2 and 4 of the power converter, 8 is a controller of the first power converter, 26 and 2
7 is a switching unit for switching between A system and B system described later, and 9 is a second
Power converter controller, 10 is a DC voltage detector, 28
Is a regular A system controller 8A and a standby B system controller 8 which will be described later.
Reference numeral 29 denotes a diagnosis unit for diagnosing an abnormality of B, and numeral 29 denotes a diagnosis unit for diagnosing an abnormality of a regular A-system control device 9A and a standby B-system control device 9B described later. The control device 8 of the first power converter is composed of a regular A system control device 8A and a standby B system control device 8B of the dual system configuration, and the DC voltage detected by the DC voltage detector 10 becomes constant. The control device mainly has the function of controlling as described above. The control device 9 for the second power converter includes a normal A system control device 9A and a standby B system control device 9B in the dual system configuration.
The control device is mainly composed of a function of controlling the generated torque of the electric motor 5 by the detection signals of the speed detector 6 and the current detector 7B to control the speed, and the first power converter 2 side is abnormal. In this case, the control device has a voltage control function of suppressing the DC voltage within a predetermined value by the signal of the voltage detector 10. In this embodiment, the difference from the conventional example of FIG. 4 is that the DC voltage detected by the voltage detector 10 is input to the regular A system control device 9A and the standby B system control device 9B, and the first power converter is used. When the second side is abnormal, the abnormality signal of the diagnosis unit 28 is sent to the normal A system control device 9A and the standby B system control device 9
This is the point of transmission to B. The operation of this embodiment is normally the same as that of the conventional example of FIG.
B) inputs the speed signal of the electric motor 5 from the speed detector 6 and the current signal from the current detector 7B, and controls the second power converter 4 by the function of speed control. by the way,
When an abnormality occurs on the first power converter 2 side, the diagnosis unit 28
Detects an abnormality and outputs an abnormality signal to the control device 9A (and 9
B). Control device 9A (and 9B) switches the function of speed control to the voltage control function of controlling DC voltage, and controls second power converter 4. This allows
Suppresses the rise of DC voltage.

FIG. 2 shows detailed blocks of the control devices 8 and 9 shown in FIG. 1 to 10 are the same as those in FIG.
A and 11B are PWM control units, 12A and 12B are d axes, and q.
A two-phase / three-phase conversion control unit that converts the two-phase shaft into three-phase alternating current,
13A and 13B are d-axis current control units that control d-axis component currents, 14A and 14B are q-axis current control units that control q-axis component currents, and 15A and 15B are AC current detections detected by current detectors 7A and 7B. 16A is a d-axis component current command unit that converts and detects the d-axis and q-axis component current signals from the value, and the current command when the first power converter 2 is operated at a power factor of 1 The power factor control command signal sets the value Id * to 0. Reference numeral 16B is a d-axis component current command unit, which is a signal that becomes an excitation current command Im * for the induction motor. 18A,
18B is a voltage command unit, 17A and 17B are voltage command units 18
Voltage detector 1 for A, 18B voltage command values Ed *, Ed ₂ *
A DC voltage control unit for controlling so that the voltage becomes 0, 19 is a speed detection unit, and 20 corresponds to the speed and generated torque of the electric motor by the speed signal ωr of the speed detection unit 19 and the q-axis current command Iq *. A primary frequency calculation unit that calculates a frequency command ω ₁ * of a voltage applied to the electric motor, 23 is a speed command unit, 22 is a torque current command so that the speed of the electric motor is controlled to a command value ωr * of the speed command unit 23. A speed control unit 21 that generates a certain q-axis current command Iq ₁ * is a speed / voltage control switching unit that selects speed control when the first power converter 2 side is normal and selects voltage control when it is abnormal. 25A and 25B are abnormality detection units. The characteristic feature of the present embodiment is that a DC voltage control unit 17B, a voltage command unit 18B, and a speed / voltage control switching unit 21 are provided.

Here, the controller 8 of the first power converter
Is the voltage on the DC side of the first power converter 2 (voltage detector 10
The DC voltage control unit 17A controls the voltage so that the detected value Ed) becomes the voltage command value Ed *, outputs the q-axis current command Ιq * that is the active component current, and the q-axis current control unit 14A outputs the active component current. The q-axis current is controlled so that the command becomes Ιq *. Moreover, since the power source side power factor of the first power converter 2 is controlled to 1.0, the d-axis current Id which is the reactive component current is set to "0".
As described above, the d-axis current control unit 13A controls the d-axis current. Then, the q-axis current control unit 14A and the d-axis current control unit 1
The control output of 3A is vector-calculated by the 2-phase / 3-phase conversion control unit 12A to perform 2-phase / 3-phase conversion control.
A creates a PWM control signal to control the first power converter 2. The control device 9 of the second power converter normally
The speed control unit 22 performs speed control so that the speed of the electric motor 5 (detected value ωr of the speed detector 19) becomes the speed command value ωr *, and the q-axis current command Ιq ₁ * becomes the torque component current of the electric motor.
(Normally, Ιq * = Ιq ₁ *) is output, and the q-axis current control unit 14B controls the q-axis current so that the torque component current command is Ιq *. Further, the d-axis current control unit 13B performs d-axis current control which is an exciting current component so that the exciting current of the electric motor 5 becomes the exciting current command value Im *. Then, the control outputs of the d-axis current control unit 13B and the q-axis current control unit 14B are vector-calculated by the 2-phase / 3-phase conversion control unit 12B,
Performs 2-phase / 3-phase conversion control, and PW is performed by the PWM control unit 11B.
The M control signal is generated, and the second power converter 4 is controlled so as to have the command value of the speed of the electric motor 5 and the exciting current. In the calculation in the 2-phase / 3-phase conversion control unit 12B, the frequency command ω ₁ * calculated in the primary frequency calculation unit 20 is used as the reference signal. The current component detectors 15A and 15B detect the currents of the q-axis and d-axis components of the first and second power converters and detect the feedback values of the q-axis and d-axis current control. On the other hand, at the time of abnormality, the abnormality detection unit 25A detects the abnormality, and the speed / voltage control switching unit 21 switches from the speed control unit 22 to the DC voltage control unit 17B by this abnormality signal, and the DC voltage Ed is the second voltage command. The DC voltage control unit 17B controls the voltage so that the value becomes Ed ₂ *, and outputs the q-axis current command Iq ₂ *. The Iq ₂ * the Iq ₁ * instead of a torque component current, the Iq ₂ * and torque component current command Iq * as the active component current for voltage control, q-axis current control. Im *, which is an exciting current component, is a reactive component current.

FIG. 3 is a detailed configuration diagram of the first power converter 2 and the second power converter 4 shown in FIGS. 1 and 2. Three
0UP to WN are GTO elements, 31UP to WN are diodes, 1 (or 5) is a power source (or electric motor), 3
Indicates a smoothing capacitor.

The operation when the control unit 8A in operation becomes abnormal and the control unit 8B is switched to the standby control unit 8B will be described with reference to FIG. When an abnormality occurs in the control device 8A, the first power converter is stopped, so the power P _O regenerated by the power supply 1 from the smoothing capacitor 3 side becomes 0. '
At the same time as stopping the first power converter, the control device 8A
Is transmitted to the control device 9A of the second power converter via the diagnostic unit 28, and the control device 9A of the second power converter is transmitted.
The function of A is switched from speed control to voltage control. That is, in FIG. 2, an abnormality signal is transmitted from the abnormality detection unit 25 that detects the abnormality of the control device 8A to the speed / voltage control switching unit 21 of the control device 9A of the second power converter, and the q-axis current command Iq ₁ The speed control unit 22 generating * is switched to the DC voltage control unit 17B. The DC voltage control unit 17B determines that the DC voltage value Ed detected by the voltage detector 10 is the voltage command value Ed *.
The q-axis current command Iq ₂ * is output so as to be controlled by.
“On the side of the second power converter 4, the control device 9A is switched to the function of controlling the DC voltage.
Power P that enters the smoothing capacitor 3 side that attempts to overcharge
Control _I to 0. Therefore, when the first power converter 2 is temporarily stopped by switching from the control device 8A to the control device 8B, an increase in the DC voltage is suppressed. In this period, the d-axis current control system 16B that controls the exciting current,
In 13B, since the exciting current is an ineffective component, the direct current voltage does not fluctuate, and by continuously controlling the exciting current, the exciting current can be kept constant and the operation of the electric motor with constant magnetic flux continues. Thereby, after switching from the control device 8A to 8B, the control device 9A is switched from the voltage control to the speed control, and when the control function of the second power converter 4 is restored, the DC voltage and the magnetic flux are constantly established. As a result, smooth normal operation can be resumed.

FIG. 7 shows another embodiment of the present invention. 1 to
25 is the same as FIG. 2 is different from FIG. 2 in that when the DC voltage exceeds a predetermined value exceeding the voltage command value Ed * on the first power converter 2 side, an overvoltage detector 50 for detecting this voltage is provided. The overvoltage level signal detected by the detector 50 is transmitted to the speed / voltage control switching unit 21 of the control device 9A of the second power converter, and the q-axis current command Iq is transmitted.
₁ * generating speed control unit 22 to DC voltage control unit 17B
In other words, switching from speed control to voltage control. If an abnormality occurs in the control device 8A, the first
Since the power converter of 1 is stopped, the power P _O regenerated from the smoothing capacitor 3 side to the power source 1 becomes 0. on the other hand,
The power P _I flows from the second power converter 4 into the smoothing capacitor 3 and tries to overcharge the smoothing capacitor 3 (FIG. 6).
See). The overvoltage detector 50 detects the overvoltage, and when the direct current voltage exceeds a predetermined value exceeding the voltage command value Ed *, the overvoltage level signal is used to control the speed / voltage of the control device 9A of the second power converter. The speed control unit 22 which transmits the q-axis current command Iq ₁ * to the switching unit 21 is switched to the DC voltage control unit 17B, and the DC voltage value Ed detected by the voltage detector 10 is controlled to the voltage command value Ed *. To output the q-axis current command Iq ₂ *. Hereinafter, as described in the operation of FIG. 6, on the second power converter 4 side, since the control device 9A switches to the function of controlling the DC voltage, the smoothing capacitor 3
Power P that enters the smoothing capacitor 3 side that attempts to overcharge
Suppress _I. Therefore, when the DC voltage becomes equal to or higher than a predetermined value that exceeds the voltage command value Ed *, the increase of the DC voltage is suppressed. Further, in this period, since the d-axis current control system 16B, 13B that controls the exciting current has the exciting current as an ineffective component, there is no fluctuation of the DC voltage, and the exciting current is kept constant by controlling continuously. Therefore, the operation of the motor with constant magnetic flux continues. As a result, after the control device 8A is switched to the control device 8B, when the DC voltage returns to the predetermined value exceeding the voltage command value Ed * or less, the control device 9A is switched from the voltage control to the speed control, and the second power converter 4 is operated. When the control function of is restored to its original value, the DC voltage and the magnetic flux are constantly established, so that smooth normal operation can be resumed.

FIG. 8 shows another embodiment of the present invention. 1 to
25 is the same as FIG. 2 is different from the speed / voltage control switching unit 21 in that the DC voltage control unit 17B sends a q-axis current command Ιq ₁ * output from the speed control unit 22 when the DC voltage becomes a predetermined level or higher. A correction controller 21B for correcting the q-axis current command Iq ₂ * to be output is provided,
It is to control the DC voltage. In FIG. 9, the correction controller 2
1B shows a detailed block of 1B. 51 limiter portion a DC voltage to output a signal proportional to the deviation voltage set value Ed ₂ * or more, the voltage setting value Ed ₂ * The following outputs "0", 52
Is a DC voltage control unit 17B based on the output signal of the speed control unit 22.
Is a deviation widening unit for giving priority to the output signal of, and 53 is a subtracting unit. In the present embodiment, even if the first power converter 2 side is not abnormal, when the load of the second power converter 4 suddenly changes, power flows from the second power converter 4 to the smoothing capacitor 3. Then, the smoothing capacitor 3 tries to be overcharged. The correction control unit 21B inputs the q-axis current command Ιq ₁ * from the speed control unit 22 and the q-axis current command Iq ₂ * from the DC voltage control unit 17B, and the DC voltage becomes the voltage set value Ed ₂ * or more. In this case, a signal proportional to the deviation is output via the deviation widening unit 52 with priority over the q-axis current command Ιq ₁ and the subtraction unit 53 outputs the DC voltage and the voltage set value Ed ₂ from the q-axis current command Ιq ₁ *. A signal proportional to the deviation of * is subtracted, that is, the q-axis current command Ιq ₁ * is corrected, and Iq * is output as an active component current for voltage control. Therefore, the second power converter 4 is voltage-controlled based on the corrected q-axis current command Iq *, and suppresses the electric power that enters the smoothing capacitor 3 side that attempts to overcharge the smoothing capacitor 3. When the load returns to the normal state and the DC voltage in the limiter unit 51 becomes equal to or lower than the voltage setting value Ed ₂ *, the q-axis current command Iq ₂ * is output as "0", and the control device 9 of the second power converter 4 is output. The control function of is restored to its original value, and the speed of the second power converter 4 is controlled. As a result, it is possible to control the rise of the DC voltage that occurs due to a sudden change in the load to a fixed value or less, and it is possible to greatly reduce the capacity of the smoothing capacitor. Further, as shown in FIG. 10, when the characteristics of the limiter section 51 are set to the upper and lower limiter characteristics with the upper limit limiter value Ed ₂ and the lower limit limiter value Ed ₁ , the DC voltage shown in FIG. It can also have functions.

In the embodiment described above, the GTO is used as the self-extinguishing element, but the present invention is
Even if all self-extinguishing elements such as GBTs, transistors, IGCTs, and SI thyristors are used, the same effect can be obtained by the same control method. Further, in the embodiment described above, an example is shown in which the normal A-system control device 8A of the first power converter is switched to the standby B-system control device 8B when an abnormality occurs on the first power converter side or when the load changes suddenly. However, the present invention can be applied even when the control is switched from the regular A system 8A to the standby B system 8B or vice versa for normal maintenance or the like.

[0015]

As described above, according to the present invention,
When the abnormality of the first power converter side or the switching of the control device is performed, the second power converter is operated by the function of controlling the voltage, so that the rise of the DC voltage can be suppressed. Further, since the fluctuation of the DC voltage caused by the sudden change of the load is suppressed within a predetermined value, the capacity of the smoothing capacitor can be greatly reduced. Even if the control switching on the first power converter side occurs,
Since the exciting current of the load is continuously controlled by the power converter of No. 2, the magnetic flux can be kept constant and the DC voltage can be kept within a predetermined range. There is an effect that the operation can be continued by returning to the control.

[Brief description of drawings]

FIG. 1 shows a P using a GTO element showing an embodiment of the present invention.
Block diagram of WM power converter

FIG. 2 is a detailed block diagram of the control device shown in FIG.

FIG. 3 is a configuration diagram of a power converter

FIG. 4 is an explanatory diagram of a conventional technique.

FIG. 5 is an explanatory diagram of a conventional technique.

FIG. 6 is an operation explanatory diagram of the present invention.

FIG. 7 is another embodiment of the present invention.

FIG. 8 is another embodiment of the present invention.

FIG. 9 is a partial detailed block diagram of FIG.

FIG. 10 is a limiter characteristic diagram of FIG.

[Explanation of symbols]

 1 Power Supply 2, 4 Power Converter 5 Induction Motor 8, 9 Control Device 8A, 9A Regular A System Control Device 8B, 9B Standby B System Control Device 10 DC Voltage Detector 28 Diagnostic Unit 17 DC Voltage Control Unit 18 Voltage Command Unit 21 Speed / voltage control switching unit 21B Correction control unit 22 Speed control unit 23 Speed command unit 25 Abnormality detection unit 50 Overvoltage detector 51 Limiter unit

Claims (11)

[Claims] 1. A first power converter and a second power converter for supplying electric power from a power supply to a load such as an electric motor using the self-extinguishing element and for regenerating electric power from the load such as the electric motor to the power supply. In a power conversion device including a power supply device, a second power conversion device that converts an alternating current of a power supply into a direct current voltage into electric power required for speed control and torque control of a load such as an electric motor when an abnormality occurs A method for controlling a power conversion device, characterized in that the power exchanger is switched to a function for controlling a DC voltage to suppress an increase in the DC voltage. 2. A first power converter and a second power converter, which use a self-extinguishing element to supply electric power from a power supply to a load such as an electric motor and to regenerate electric power from the load such as an electric motor to the power supply. And a control device for the first power converter in a dual system, the second power converter when it is necessary to switch from one control device to the other control device. Is switched from a speed control function for controlling the speed and torque of a load such as an electric motor to a voltage control function for controlling a DC voltage, and after switching the control device of the first power converter,
A method of controlling a power converter, wherein the control function of the second power converter is returned to the original state and the operation of the load is continued. 3. A first power converter and a second power converter, which use a self-extinguishing element to supply electric power from a power supply to a load such as an electric motor and to regenerate electric power from the load such as an electric motor to the power supply. In a power conversion device including a voltage converter, when the converted DC voltage exceeds a predetermined value, the second power converter controls the DC voltage from a speed control function that controls the speed and torque of a load such as an electric motor. A control method for a power conversion device, comprising switching to a control function and suppressing a rise in a DC voltage. 4. The electric power according to claim 3, wherein when the DC voltage to be converted becomes equal to or lower than a predetermined value, the control function of the second power converter is restored to continue the operation of the load. Control method of converter. 5. A first power converter and a second power converter, which use a self-extinguishing element to supply electric power from a power supply to a load such as an electric motor and to regenerate electric power from the load such as an electric motor to the power supply. In a power conversion device including a power converter, when the DC voltage to be converted becomes equal to or higher than a predetermined set voltage, a command for speed control is set to the DC voltage and the setting as a control function of the control device of the second power converter. A control method for a power conversion device, characterized in that the voltage is corrected by a deviation of the voltage, and the direct current voltage is controlled based on the corrected command to suppress an increase in the direct current voltage. 6. The predetermined set voltage according to claim 5,
A control method for a power conversion device, characterized in that the upper limit and the lower limit of the converted DC voltage are set. 7. The method for controlling a power conversion device according to claim 3, wherein the control device of the first power converter is configured in a dual system. 8. A first power converter and a second power converter for supplying electric power from a power supply to a load such as an electric motor using the self-extinguishing element and regenerating electric power from the load such as an electric motor to the power supply. In a power converter comprising a power converter, the controller for the first power converter detects an abnormality, and the controller for the second power exchanger has a speed control function for performing speed control and torque control of a load such as an electric motor. Switching means for switching between a voltage control function for controlling a DC voltage converted to
2. The control device for a power converter, wherein the control function of the controller for the second power exchanger is switched to the voltage control function when the power converter is abnormal. 9. A first power converter and a second power converter that use a self-extinguishing element to supply electric power from a power supply to a load such as an electric motor and to regenerate electric power from the load such as an electric motor to the power supply. In a power conversion device including a switch, when the converted DC voltage exceeds a predetermined value, a means for detecting this and a control device for the second power exchanger perform speed control and torque control of a load such as an electric motor. A switching means for switching between the speed control function and the voltage control function for controlling the DC voltage is provided, and when the DC voltage exceeds a predetermined value, the control function of the control device of the second power exchanger is switched to the voltage control function. A control device for a characteristic power converter. 10. The first power converter according to claim 8 or 9, wherein the control device is configured in a dual system.
The control device of the power conversion device, wherein the switching means restores the control function of the second power converter after switching from one control device to the other control device. 11. A first power converter and a second power converter that use a self-extinguishing element to supply electric power from a power supply to a load such as an electric motor and regenerate electric power from the load such as an electric motor to the power supply. In a power conversion device including a power supply, when the converted DC voltage is equal to or higher than a predetermined set voltage or lower than or equal to a predetermined set voltage, a means for correcting a command for speed control by a deviation between the DC voltage and the set voltage is provided. A control device for a power converter, wherein the control device for a second power converter controls DC voltage based on the corrected command.