JPH08223931A - Power conversion apparatus - Google Patents

Abstract

PURPOSE: To obtain a power conversion apparatus which can be operated stably even when an overload capacity is very large or a large overload is changed suddenly. CONSTITUTION: In a power conversion apparatus, switching energy in GTO thyristors S1, S2 is collected once by a regenerative capacitor CC1, and the energy is regenerated to a main DC power supply Ed via chopper circuits (SC1, SC2, DC1, DC2). In the power conversion apparatus, a voltage in the regenerative capacitor CC1 whose voltage is controlled by the chopper circuits after the level of a main circuit current has been detected by a load-current level discriminator LD changes a regenerative-voltage reference value to REF2 from REF1 by a changeover device CH when the level of the main circuit current is at a prescribed value or higher. Thereby, a chopper voltage reference REFC is lowered, and the continuity period the GTO thyristors for the chopper circuits is controlled by a chopper voltage reference REFC via the lowered chopper voltage reference REFC so as to be controlled to a low voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power conversion device which is composed of a power device such as a GTO (gate turn-off thyristor) or an electrostatic induction type device and which can convert power and can be used for applications in which load fluctuations are severe.

[0002]

2. Description of the Related Art As an example of this type of conventional power conversion device, there is an inverter device for converting DC power into AC power. FIG. 8 shows the main circuit of the inverter device shown in US Pat. No. 4,566,051. As shown in FIG. 8, it is composed of a main DC power source Ed, a DC filter capacitor C1, regenerative reactors LC1 and LC2, regenerative GTOSC1 and SC2, regenerative capacitors CC1 and CC2, a load motor M1, and an inverter circuit INV.

The inverter circuit INV is composed of GTOS1 and S2 constituting one phase, diodes D1 and D2, snubber diodes DS11 and DS12 and DS21 and DS22.

Although FIG. 8 shows only one phase, 3
In the case of the phase inverter circuit INV, three sets of the illustrated circuits are provided, which converts DC power into three-phase AC power and outputs this three-phase AC power.

In the main circuit having such a configuration, the regenerative capacitors CC1 and CC2, the regenerative GTOSC1 and SC
2, the regenerative diodes DC1 and DC2, and the regenerative reactors LC1 and LC2 each recover the energy generated when the GTOS1 and S2 are turned on and off to the regenerative capacitors CC1 and CC2 respectively. The regenerative GTOSC1 (SC2) and the regenerative Diode DC
1 (DC2) and the regenerative reactor LC1 (LC2), which is a chopper circuit and is regenerated by the main DC power source Ed.

FIG. 9 is for explaining the control circuit of the inverter device described above. Here, since the operations of the regeneration capacitor CC1 side and CC2 side are the same, the control operation of only the regeneration capacitor CC1 side will be explained. To do. GT
When OS1 is turned off, the switching energy determined by the main circuit current and the wiring inductance of the main circuit is transferred to the snubber capacitor CS1 and the regeneration capacitor CC1. On the other hand, when the GTOS1 is turned on, the charging energy of the snubber capacitor CS1 is regenerated by the regenerative capacitor CC.
Go to 1. The voltage Ecc1 of the regeneration capacitor CC1 is compared and controlled by the chopper voltage reference REFC and the comparator AMP of the chopper control circuit CNTC, and the regeneration GTOSC1
The conduction period of is controlled. That is, GTOSC for regeneration
1 and regenerative diode DC1 and regenerative reactor LC1
The regenerative capacitor C is formed by the chopper circuit formed by
The switching energy transferred to C1 is the main DC power source Ed
Regenerated to.

The average value of the voltage of the regeneration capacitor CC1 is controlled in accordance with the chopper voltage reference REFC, and the voltage fluctuation of the regeneration capacitor CC1 changes depending on the current flowing through GTOS1. In addition, regeneration capacitor CC2
The side is also controlled in the same manner and operates in the same manner, and therefore its explanation is omitted.

Since the switching energy of the regeneration capacitor CC1 and GTOS1 is regenerated to the main DC power source Ed side, the operating efficiency of the inverter circuit INV can be improved by about 20% in the circuit configuration of FIG. Further, when the inverter circuit INV has a three-phase configuration, the regenerative capacitor CC1 is generally provided with a common set of three phases.

The method of regenerating the switching energy of the regenerative condens CC1 and GTOS1 is very effective for improving the operating efficiency, but the overload capacity of the load motor M1 is 2%.
When the load motor M is very large, such as 100-300%,
When the sudden overload change of 1 is extremely severe, the inverter device of FIG. 8 has many problems in terms of operation stability.

[0010]

In the inverter device of FIG. 8, the overload capacity is determined by the conditions on the load side. For example, when the load motor M1 drives a steel rolling mill,
The overload capacity is required to be rated at 200 to 300% to 1 second, and for example, 250% load is suddenly applied or 25
It is general that the 0% load suddenly becomes zero.

When the load motor M1 is applied to such an application, in the inverter circuit INV, the current flowing through GTOS1 changes substantially in proportion to the overload capacity. Therefore, the switching energy of GTOS1 collected in the regenerative capacitor CC1 also changes in accordance with the overload capacity, and the charging voltage of the regenerative capacitor CC1 also changes in almost proportion to the current flowing in the GTOS1.

That is, in the inverter device having a large overload capacity, the fluctuation of the charging voltage of the regenerative capacitor CC1 becomes very large, and if the overload capacity is 125% and the overload capacity is 250%, the regenerative capacitor CC1 is regenerated.
The voltage fluctuation of is doubled.

When the voltage fluctuation of the regenerative capacitor CC1 is large as described above, the regenerative current of the chopper circuit fluctuates greatly and the control of the chopper circuit becomes unstable. Also, GTO
The current flowing through S1 suddenly drops from zero to 250%,
When it becomes 250% to 250%, the fluctuation of the regenerative current of the chopper circuit becomes the largest, and the control of the chopper circuit becomes more unstable.

On the other hand, the fluctuation of the charging voltage of the regenerative capacitor CC1 can be suppressed by increasing the capacity of the regenerative capacitor CC1. However, when the overload capacity is doubled, the capacity of the regenerative capacitor CC1 is reduced to 2 It is uneconomical to double the number, the external dimensions of the regenerative capacitor CC1 also increase, and the inverter device becomes expensive and large-sized.

That is, in an inverter device provided with regeneration capacitors CC1 and CC2 for regenerating switching energy of a power device such as a GTO, when the overload capacity is very large or the load changes abruptly. Had the following problems.

1) The fluctuation range of the output capacity of the inverter device is large, and the fluctuation range and the maximum value of the charging voltage of the regenerative capacitor CC1 are correspondingly large, and the control of the regenerative circuit such as the chopper circuit is also very unstable. It was easy to become.

2) When the load changes abruptly, the charging voltage of the regenerative capacitor fluctuates more drastically, and the control of the regenerative circuit tends to become very unstable. 3) If the capacity of the regenerative capacitor is increased in order to control the control instability of the regenerative circuit, the inverter device becomes large and expensive.

4) Due to the unstable control of the regenerative circuit, the voltage control of the main DC power source Ed is likely to be unstable, and it is difficult to stably control the output voltage of the inverter device. An object of the present invention is to provide an economical power conversion device that can be stably operated even when the overload capacity is very large or a large overload changes abruptly.

[0019]

In order to achieve the above-mentioned object, the invention according to claim 1 makes the regenerative capacitor once collect the switching energy accompanying the on / off operation of the power device constituting the power conversion circuit, In a power conversion device that regenerates energy to a main DC power supply through a chopper circuit, a level of a main circuit current flowing from the power conversion circuit to a load is detected by a load level discriminator, and the level of the main circuit current is a predetermined value or more. Is a power conversion device configured to control the voltage of the regeneration capacitor, which is voltage-controlled by the chopper circuit, to a low value.

In order to achieve the above object, the invention according to claim 2 causes the regenerative capacitor to once recover the switching energy accompanying the on / off operation of the power device constituting the power conversion circuit, and the energy is passed through the chopper circuit. In the power converter that regenerates the main DC power source by the load level discriminator, the level of the electric control signal corresponding to the effective portion of the main circuit current flowing from the power converter circuit to the load is detected by the load level discriminator. The power converter is configured to control the voltage of the regeneration capacitor, which is voltage-controlled by the chopper circuit, to a low value when the voltage is equal to or higher than a predetermined value.

In order to achieve the above object, the invention according to claim 3 makes the regenerative capacitor once collect the switching energy accompanying the on / off operation of the power device constituting the power conversion circuit, and the energy is passed through the chopper circuit. In a power converter that regenerates the main DC power source by the main DC power supply, an electric control signal corresponding to a main circuit current flowing from the power converter circuit to a load or an effective component of the main circuit current is changed at a rate of change in either an increasing direction or a decreasing direction. A load fluctuation detector that detects that there is a load fluctuation detector is provided, and when the change rate detected by this load fluctuation detector is in the increasing direction, the chopper control circuit that controls the voltage of the chopper circuit charges the regeneration capacitor. In order to decrease the average value of the voltage, and to give a correction signal according to the rate of change, by the load fluctuation detector When the output rate of change is in the decreasing direction, the chopper control circuit is configured to increase the average value of the charging voltage of the regenerative capacitor and to supply a correction signal according to the rate of change. It is a conversion device.

In order to achieve the above object, the invention according to claim 4 makes the regenerative capacitor once collect the switching energy accompanying the on / off operation of the power device constituting the power conversion circuit, and the energy is passed through the chopper circuit. In a power converter that regenerates power into a main DC power source by a load level discriminator, the chopper circuit detects the level of a main circuit current flowing from the power converter circuit to a load by a load level discriminator. The voltage of the regenerative capacitor, which is voltage-controlled by, is configured to be controlled to a low value, the charging current of the regenerative capacitor is detected by the regenerative current detector, and the charging current detected by this regenerative current detector increases. Direction, the load fluctuation detector is set to the chopper control circuit that controls the voltage of the chopper circuit. A correction signal for decreasing the average value of the charging voltage of the regeneration capacitor according to the rate of change of the regenerative capacitor, and when the charging current detected by the current detector is decreasing, the voltage of the chopper circuit is controlled. The power converter is configured to give a correction signal to the chopper control circuit for increasing the average value of the charging voltage of the regeneration capacitor according to the rate of change from the load fluctuation detector.

In order to achieve the above-mentioned object, the invention according to claim 5 causes the regenerative capacitor to once recover the switching energy accompanying the on / off operation of the power device constituting the power conversion circuit, and the energy is passed through the converter circuit. In a power converter that regenerates an AC power source by a load level discriminator, the converter circuit detects the level of an electric control signal corresponding to a main circuit current flowing from the power converter circuit to a load or an effective portion of the main circuit current. Is a power conversion device configured to control the voltage of the regeneration capacitor whose voltage is controlled by a low value when the level of the electric control signal is equal to or higher than a predetermined value.

In order to achieve the above-mentioned object, the invention according to claim 6 causes the regenerative capacitor to once recover the switching energy accompanying the on / off operation of the power device constituting the power conversion circuit, and the energy is passed through the converter circuit. In a power converter that regenerates an AC power source by providing a load fluctuation detector that detects a rate of change of an electric control signal corresponding to an effective portion of a main circuit current or the main circuit current flowing from the power conversion circuit to a load, A current detector for detecting the charging current of the regenerative capacitor is provided, and when the charging current detected by the current detector is in the increasing direction, the load fluctuation is applied to the converter control circuit controlling the voltage of the converter circuit. Providing a correction signal to decrease the average value of the charging voltage of the regeneration capacitor according to the rate of change from the detector When the discharge current detected by the current detector is decreasing, the converter control circuit increases the average value of the charging voltage of the regenerative capacitor according to the rate of change from the load change detector. The power converter is configured to provide a direction correction signal.

In order to achieve the above object, the invention according to claim 7 is a power converter in which a main converter circuit for controlling the voltage of a main DC power supply is provided on the input side of an inverter circuit for converting DC power into AC power. The apparatus is provided with a load fluctuation detector for detecting a rate of change of an electric control signal corresponding to a main circuit current flowing from the inverter circuit to a load or an effective portion of the main circuit current, and the load fluctuation detector is a change in a decreasing direction. The power conversion device is configured to control the output voltage of the main DC power supply in a direction to narrow it down when a state in which the rate is equal to or higher than a predetermined value is detected.

In order to achieve the above-mentioned object, the invention according to claim 8 is provided with an inverter circuit for converting the DC power obtained from the main DC power supply through a chopper circuit or a converter circuit into AC power, In a power conversion device that smoothes the power of a DC power supply with a DC filter capacitor and supplies it to the inverter circuit, the discharge current of the DC filter capacitor is detected by a current detector, and the discharge current detected by this current detector is in the increasing direction. When, for the chopper control circuit for controlling the voltage of the chopper circuit or the converter control circuit for controlling the voltage of the converter circuit, the average of the charging voltage of the regeneration capacitor according to the detection value of the current detector. A correction signal for decreasing the value is given, and the discharge current detected by the current detector decreases. In this case, the electric power configured to give the chopper control circuit or the converter control circuit a correction signal in the direction of increasing the average value of the charging voltage of the regeneration capacitor according to the detection value of the current detector. It is a conversion device.

[0027]

According to the invention corresponding to claim 1, when the level of the main circuit current is equal to or higher than a predetermined value, the voltage of the regenerative capacitor is controlled to a low value, so that the voltage control of the chopper circuit is performed. Since it can be stabilized and there is no need to increase the capacity of the regeneration capacitor, a small and inexpensive power conversion device can be obtained.

According to the invention corresponding to claim 2, when the level of the electric control signal is equal to or higher than a predetermined value, the voltage of the regeneration capacitor is controlled to a low value, so that the voltage control of the chopper circuit is performed. Since it can be stabilized and there is no need to increase the capacity of the regeneration capacitor, a small and inexpensive power conversion device can be obtained.

According to the invention of claim 3, the control response of the chopper control circuit for controlling the voltage of the chopper circuit is improved in accordance with the rate of change detected by the load fluctuation detector. The recovered energy can be regenerated stably even if the load changes rapidly.

According to the invention of claim 4, an electric signal corresponding to the charging current of the regeneration capacitor is detected, and the control response of the chopper control circuit for controlling the voltage of the chopper circuit in accordance with the detected signal is detected. Since it is configured to improve, stable power regeneration is possible with the chopper circuit.

According to the invention corresponding to claim 5, since the voltage of the regenerative capacitor is controlled to a low value when the level of the electric control signal is equal to or higher than a predetermined value, the control response is improved, Recovered energy can be regenerated stably even if the load changes rapidly.

According to the sixth aspect of the invention, the average value of the charging voltage of the regenerative capacitor is increased or decreased in accordance with the rate of change of the electric control signal corresponding to the effective amount of the main circuit current. Since the correction signal of 1 is given to the converter control circuit, the control response is improved and the recovered energy can be regenerated stably even if the load changes rapidly.

According to the invention of claim 7, a load fluctuation detector for detecting the rate of change of the main circuit current or the electric control signal corresponding to the effective portion of the main circuit current is provided, and the load fluctuation detector is reduced by a predetermined value or more. When the rate of change in direction is detected, the output voltage of the main DC power supply is controlled to be narrowed down, so that the voltage rise of the main DC power supply can be suppressed and stabilized.

According to the invention corresponding to claim 8, the discharge current of the DC filter capacitor is detected to improve the control response of the control circuit of the chopper circuit or the converter circuit.
Since the discharge current of the DC filter capacitor is detected and the detection is performed in response to this detection signal, power regeneration can be stabilized.

[0035]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment (Embodiment Corresponding to Claim 1)> As shown in FIG. 1, the point different from FIGS. 8 and 9 is that the main circuit current detector is used to control the voltage of the regeneration capacitor CC1. CT1, load level discriminator LD, regenerative voltage reference value REF
Regenerative voltage reference EREF having a switch CH capable of switching and outputting either 1 or REF2 and a comparator C
A chopper control circuit CNTC having an OM, an amplifier AMP, and a gate GATE is newly added, and in order to control the voltage of the regeneration capacitor CC2 in the same manner, although not shown, a main circuit current detector (CT1 which is the same as in FIG. 1), Regenerative voltage reference having a switch (same CH as in FIG. 1) that can switch and output either a load level discriminator (same LD as in FIG. 1) or a regenerative voltage reference (same values REF1 and REF2 as in FIG. 1) With a new container (the same EREF as in Fig. 1),
Other than that, the same parts as those in FIG. 8 have the same functions.

Here, these configurations will be described, but since the regeneration capacitor CC1 side and the CC2 side have the same configuration, only the regeneration capacitor CC1 side will be described. That is, the main circuit current detector CT1 detects the main circuit current flowing from the inverter circuit INV to the load motor M1, and the load level discriminator LD detects the main circuit current detector CT1.
A signal is output when the current detected by exceeds a predetermined value.

The switching device CH of the regenerative voltage reference device EREF switches the regenerative voltage reference value from REF1 to REF2 when the output signal is output from the load level discriminator LD, and outputs the output signal from the load level discriminator LD. If not, the regenerative voltage reference value is not switched and REF1 in FIG.
It remains as it is.

Then, in the comparator COM of the chopper control circuit CNTC, the output of the regenerative voltage reference device EREF, REFC, is compared with the regenerative voltage ECC1 applied to the regenerative capacitor CC1, and this deviation is compared with the amplifier AMP and the gate. It is given to the gate of the regenerative GTOSC1 via GATE, so that the conduction period of the GTOSC1 is controlled.

In FIG. 1, the main circuit current corresponding to the output power of the inverter circuit INV is detected by the current detector CT1. In this case, the switching energy accompanying the ON / OFF operation of GTOS1 or S2 is recovered by the regeneration capacitor CC1 or CC2, and
This energy is regenerated to the main DC power source Ed via the chopper circuit by turning on and off the regeneration GTO SC1 or SC2.

The switching energy in this case is detected by the main circuit current detector CT1 and the load level discriminator LD determines whether or not the detected value exceeds a predetermined level. An output signal is generated from the load level discriminator LD when the switching energy exceeds a predetermined level. When an output signal is obtained from the load level discriminator LD,
The switch CH of the regenerative voltage reference device EREF operates to switch the regenerative voltage reference value from REF1 to REF2, and the chopper voltage reference REFC is lowered. This chopper voltage reference REFC and the regenerative voltage ECC of the regenerative capacitor CC1
1 is compared by the comparator COM of the chopper control circuit CNTC, and this deviation is amplified through the amplifier AMP and the gate GATE and a signal is given to the gate of the regenerative GTOS1. As a result, the maximum value of the charging voltage of the regeneration capacitor CC1 is also lowered, and the voltage control of the chopper circuit is stabilized.

According to the first embodiment described above, the average value of the charging voltage of the regeneration capacitor CC1 is variably controlled in response to a large overload capacity and a sudden change in the main circuit current. Therefore, the operation of the chopper circuit becomes stable, and the power conversion device can be operated stably.

The first embodiment can be modified and implemented as follows. That is, the chopper voltage reference REFC that is changed by the regenerative voltage reference device EREF may be switched in a plurality of stages stepwise, or continuously changed, as in the above-described embodiment. In addition, the main circuit current detector CT1
Need only be provided in the loop for detecting the current flowing through GTOS1 and is not limited to the position shown in FIG.

<Second Embodiment (Embodiment Corresponding to Claim 2)> As shown in FIG. 2, the main circuit current detector CT1, the load level detector LD, and the inverter circuit I of the embodiment shown in FIG.
The difference from the embodiment of FIG. 1 is that a main control circuit CNTM is added between NVs. The main control circuit CNTM extracts an electric control signal Iq corresponding to an effective portion of the main circuit current detected by the main circuit current detector CT1, which is a known vector control technique for the load motor M1. It was used.

The electric control signal Iq extracted by the main control circuit CNTM is input to the load level discriminator LD, and it is discriminated whether or not the electric control signal Iq exceeds a predetermined level. When the electric control signal Iq exceeds the predetermined level, regeneration is performed. Voltage reference device EREF
A switching command is given to the switching device CH.

In the configuration as described above, the electric control signal Iq corresponding to the effective portion of the main circuit current obtained in the main control circuit CNTM is input to the load level discriminator LD,
The regenerative voltage reference EREF can be variably controlled.

As a result, even if the overload capacitance changes or the main circuit current fluctuates abruptly, this is indirectly detected by the electric control signal Iq, so the regeneration capacitor CC1
The average value of the charging voltage can be variably controlled, the operation of the chopper circuit becomes stable, and the power converter can be operated stably.

<Third Embodiment (Embodiment Corresponding to Claim 3)> As shown in FIG. 3, the load level discriminator LD of FIG.
In addition, the regenerative voltage reference device EREF is not provided, and the load variation detector DI and the regenerative voltage reference device EREF having only one regenerative voltage reference REF1 are newly provided.

In this case, the load change detector DI obtains the rate of change (di / dt) of the main circuit current detected by the main circuit current detector CT1 and the obtained rate of change (di / d).
t) is input to the amplifier AMP of the chopper control circuit CNTC, and a correction signal is given to the chopper control circuit CNTC. And the regenerative voltage reference device ERE
The regenerative voltage reference REF1 of F and the regenerative voltage ECC1 of the regenerative capacitor CC1 are input to the comparator COM of the chopper control circuit CNTC.

In the embodiment constructed as shown in FIG. 3, for example, when the main circuit current makes a large change in the rapid increase direction,
A correction signal is sent to the chopper control circuit CNTC to decrease the average value of the charging voltage of the regeneration capacitor CC1 quickly or to increase the average value of the charging voltage of the regeneration capacitor CC1 slowly when the main circuit current decreases. input. As a result, the chopper control circuit CNTC can improve and stabilize the control response even if the main circuit current fluctuates rapidly.

In the embodiment shown in FIG. 3, the current detected by the main circuit current detector CT1 is input to the load variation detector DI. The current detected by the main circuit current detector CT1 is shown in FIG. Thus, even if the electric control signal Iq corresponding to the effective portion of the main circuit current obtained by inputting to the main control circuit CNTM is input to the load change detector DI, the same effect as the embodiment of FIG. 3 can be obtained. it can.

<Fourth Embodiment (Embodiment Corresponding to Claim 4)> As shown in FIG. 4, the regeneration capacitor CC of FIG.
The charge / discharge current of 1 is detected by the regenerative current detector CT2, and the detected current is the amplifier AM of the chopper control circuit CNTC.
The only difference from FIG. 1 is that it is configured to input to P.

With this configuration, when the charging current of the regenerative capacitor CC1 increases, the detection current of the regenerative current detector CT2 detecting this changes in an increasing direction. Then, the correction signal is input to the chopper control circuit CNTC in the direction of rapidly reducing the average value of the charging voltage.

When the charging current of the regenerative capacitor CC1 decreases, the regenerative current detector CT2 that detects this decreases.
The detected current changes to decrease and the correction signal is input to the chopper control circuit CNTC in the direction of increasing the average value of the charging voltage quickly. Therefore, the operation of the chopper circuit can be stabilized and the power converter can be operated stably.

<Fifth Embodiment (Embodiment Corresponding to Claim 5 or Claim 6)> As shown in FIG. 5, the regenerative diodes DC1 and DC2 and the regenerative GTOSC1 and SC2 shown in FIG.
Chopper circuit and chopper control circuit CNT
AC is omitted, AC power supplies AC1 and AC2, converters CNV1 and CNV2 are newly added, and a regeneration capacitor CC1 is added.
1 is different from FIG. 1 in that the recovered energy of CC2 is connected to the AC power supply AC1 or AC2 via the converter CNV1 or CNV2 so as to be regenerated, and the other points are the same as in FIG.

In the circuit shown in FIG. 5, when the detection signal of the main circuit current detector CT1 exceeds a predetermined value, an output signal is generated from the load level discriminator LD, and this output signal causes the switching device CH to operate and the regenerative voltage. Reference value is from REF1 to RE
Switching to F2, which causes regeneration capacitor CC1
The maximum value of the charging voltage of is also limited as in FIG. 1, and the voltage control of the converter CNV1 is also stabilized.

Similar effects can be obtained by modifying the circuit shown in FIG. 5 as follows. That is, as in FIG. 2, a main control circuit CNTM for extracting the electric control signal Iq corresponding to the effective component of the main circuit current may be provided between the main current detector CT1 and the load level discriminator LD.

Further, similarly to FIG. 3, the load fluctuation detector DI
May be provided to input the output signal of the load fluctuation detector DI to the converter control circuit CNTR, whereby the voltage control of the converter CNV1 can be stabilized.

Further, as in FIG. 4, the regenerative current detector C
The correction signal can be input to the converter control circuit CNTR by the detection signal of T2. Even when the energy recovered from the regenerative capacitor CC1 is regenerated to the AC power supply AC1 by the converter CNV1, even when the overload capacity changes or the main circuit current fluctuates rapidly, it is possible to regenerate the energy in the chopper circuit. Similarly, the regeneration of the converter CNV1 can be stably operated, and the power conversion device can be stably operated.

<Sixth Embodiment (Embodiment Corresponding to Claim 7)> As shown in FIG. 6, the main DC power source Ed1 is reduced in voltage by the output signal of the load fluctuation detector DI shown in FIG. In order to control the output voltage of the DC power source Ed1,
It is different from FIG. 3 in that it is configured by a main converter circuit, and is otherwise the same as FIG.

With this configuration, when the main circuit current is rapidly reduced, the energy stored in the inductance of the main circuit flows into the DC filter capacitor C1 and the voltage of the main DC power source Ed1 is about to rise rapidly. However, by detecting this, the voltage change of the main DC power supply Ed1 is controlled so as to be narrowed, whereby the voltage rise of the main DC power supply Ed1 can be suppressed, and the voltage control of the power conversion device can be stabilized.

In the embodiment of FIG. 6, the current detected by the main circuit current detector CT1 is input to the load fluctuation detector DI. The current detected by the main circuit current detector CT1 is shown in FIG. Even when the electric control signal Iq corresponding to the effective component of the main circuit current obtained by inputting to the main control circuit CNTM is input to the load change detector DI, the same effect as that of the embodiment of FIG. 6 can be obtained. it can.

<Seventh Embodiment (Embodiment Corresponding to Claim 8)> As shown in FIG. 7, the main circuit current detector CT1, the load level discriminator LD and the regenerative voltage reference EREF of the circuit of FIG. Instead of using the regenerative voltage reference device EREF having a regenerative voltage reference value REF1, the connection position of the DC filter capacitor C1 is moved from the connection point between the main DC power supply Ed and the regenerative reactors LC1 and LC2. Current detector C which is connected between the capacitors CC1 and CC2 for detecting the discharge current of the DC filter capacitor C1
T3 is provided and this detected current is supplied to the chopper control circuit CNTC.
1 is different from that of FIG. 1 in that the amplifier AMP of FIG.

In the circuit of FIG. 7 configured as above,
Since the discharge current of the DC filter capacitor C1 detected by the current detector CT3 and the charging current detected by the regenerative current detector CT2 of the regenerative capacitor CC1 change in relation to each other, the detection signal of the regenerative current detector CT2 becomes Instead, it is possible to stabilize the voltage control of the chopper control circuit CNTC and converter control circuit CNTR of the current detector CT3.
The power converter can be operated stably.

<Modifications of the Invention> The present invention is not limited to the above-described embodiments, but can be applied to the following, for example. In the embodiment, the example in which the main circuit has the inverter circuit INV for converting DC power into AC power has been described. However, the switching accompanying the ON / OFF operation of a power device used in a converter circuit for converting AC power into DC power is performed. It may be a power conversion device that recovers energy in a regeneration capacitor and regenerates this recovered energy.

[0065]

According to the present invention, it is possible to provide a power conversion device which can be stably operated even if the overload capacity is very large or a large overload changes abruptly.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram for explaining a first embodiment of a power conversion device according to the present invention.

FIG. 2 is a schematic configuration diagram for explaining a second embodiment of the power conversion device according to the present invention.

FIG. 3 is a schematic configuration diagram for explaining a third embodiment of the power conversion device according to the present invention.

FIG. 4 is a schematic configuration diagram for explaining a fourth embodiment of the power conversion device according to the present invention.

FIG. 5 is a schematic configuration diagram for explaining a fifth embodiment of the power conversion device according to the present invention.

FIG. 6 is a schematic configuration diagram for explaining a sixth embodiment of the power conversion device according to the present invention.

FIG. 7 is a schematic configuration diagram for explaining a seventh embodiment of the power conversion device according to the present invention.

FIG. 8 is a schematic configuration diagram for explaining a main circuit of a conventional inverter device.

FIG. 9 is a schematic configuration diagram for explaining a control circuit of a conventional inverter device.

[Explanation of symbols]

Ed, Ed1 ... Main DC power supply, C1 ... DC filter capacitor, INV ... Inverter circuit, S1, S2 ... GTO,
D1, D2 ... Diode, DS11, DS12, DS21, D
S22 ... Snubber diode, CS1, CS2 ... Snubber capacitor, CC1CC2 ... Regeneration capacitor, SC1, SC2
… Regeneration GTO, DC1, DC2… Regeneration diodes, LC1, LC2… Regeneration reactor, M1… Load motor, REFC… Chopper voltage reference, ECC1… Regeneration voltage, CNTC… Chopper control circuit, CT1… Main circuit current detector , LD ... Load level discriminator, EREF ... Regenerative voltage reference device, Iq ... Electrical control signal, DI ... Load fluctuation detector, C
T2 ... Regenerative current detector, CNTR ... Converter control circuit, REFR ... Converter voltage reference, CT3 ... Current detector.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location H02M 3/155 H02M 3/155 R H02P 7/63 302 H02P 7/63 302C

Claims (8)

[Claims] 1. A power converter in which switching energy associated with on / off operation of a power device that constitutes a power converter circuit is once recovered by a regenerative capacitor, and the energy is regenerated to a main DC power source via a chopper circuit, The level of the main circuit current flowing from the conversion circuit to the load is detected by the load level discriminator, and when the level of the main circuit current is equal to or higher than a predetermined value, the voltage of the regeneration capacitor controlled by the chopper circuit is lowered. A power converter configured to control the value. 2. A power converter in which switching energy associated with on / off operation of a power device constituting a power converter circuit is once recovered by a regenerative capacitor, and the energy is regenerated to a main DC power source through a chopper circuit, The level of the electric control signal corresponding to the effective portion of the main circuit current flowing from the conversion circuit to the load is detected by the load level discriminator, and the voltage is controlled by the chopper circuit when the level of the electric control signal is a predetermined value or more. A power conversion device configured to control the voltage of the regeneration capacitor to a low value. 3. A power converter in which switching energy associated with on / off operation of a power device constituting a power converter circuit is once recovered by a regenerative capacitor, and the energy is regenerated to a main DC power source via a chopper circuit, A load fluctuation detector is provided for detecting whether the main circuit current flowing from the conversion circuit to the load or the electrical control signal corresponding to the effective portion of the main circuit current has a change rate in either an increasing direction or a decreasing direction. When the rate of change detected by the fluctuation detector is in the increasing direction, with respect to the chopper control circuit that controls the voltage of the chopper circuit, in the direction of decreasing the average value of the charging voltage of the regeneration capacitor, and in the rate of change. A corresponding correction signal is given, and when the rate of change detected by the load change detector is decreasing, the chopper control is performed. The circuit, the power conversion device in the direction increasing the average value of the charging voltage, and configured to constitute Ni will give a correction signal corresponding to the rate of change of the regenerative capacitor. 4. A power converter in which switching energy associated with on / off operation of a power device constituting a power converter circuit is once recovered by a regenerative capacitor, and the energy is regenerated to a main DC power source via a chopper circuit. The level of the main circuit current flowing from the conversion circuit to the load is detected by the load level discriminator, and when the level of the main circuit current is equal to or higher than a predetermined value, the voltage of the regeneration capacitor controlled by the chopper circuit is lowered. When the charging current detected by the regenerative current detector is in the increasing direction, the chopper for controlling the voltage of the chopper circuit is used. For the control circuit, the charging voltage of the regeneration capacitor according to the rate of change from the load change detector When the charging current detected by the current detector is in the decreasing direction, the load fluctuation detector is supplied to the chopper control circuit that controls the voltage of the chopper circuit. A power conversion device configured to give a correction signal in a direction of increasing the average value of the charging voltage of the regeneration capacitor according to the rate of change from. 5. A power conversion device in which switching energy associated with on / off operation of a power device that constitutes a power conversion circuit is once recovered by a regenerative capacitor, and the energy is regenerated to an AC power supply via a converter circuit. A main circuit current flowing from a circuit to a load or a level of an electric control signal corresponding to an effective portion of the main circuit current is detected by a load level discriminator, and the voltage of the regeneration capacitor voltage-controlled by the converter circuit is A power converter configured to control to a low value when the level of an electric control signal is equal to or higher than a predetermined value. 6. A power conversion device in which switching energy associated with on / off operation of a power device that constitutes a power conversion circuit is once recovered by a regenerative capacitor, and the energy is regenerated to an AC power source via a converter circuit. Provided is a load fluctuation detector that detects the rate of change of an electric control signal corresponding to a main circuit current flowing from a circuit to a load or an effective portion of the main circuit current, and a current detector that detects a charging current of the regeneration capacitor. When the charging current detected by the current detector is in the increasing direction, the converter control circuit that controls the voltage of the converter circuit is controlled by the regenerative capacitor according to the rate of change from the load change detector. A correction signal is given to decrease the average value of the charging voltage, and the charging current detected by the current detector is reduced. When the direction is small, a power conversion configured to give the converter control circuit a correction signal in a direction of increasing the average value of the charging voltage of the regeneration capacitor according to the rate of change from the load fluctuation detector. apparatus. 7. A power converter in which a main converter circuit for controlling the voltage of a main DC power supply is provided on the input side of an inverter circuit for converting DC power into AC power, wherein a main circuit current flowing from the inverter circuit to a load or A load change detector for detecting a change rate of the electric control signal corresponding to the effective portion of the main circuit current is provided, and the load change detector detects the main change when the change rate in the decreasing direction is equal to or more than a predetermined value. A power conversion device configured to control the output voltage of a DC power supply in a direction to narrow it down. 8. An inverter circuit for converting the DC power obtained from the main DC power supply through a chopper circuit or a converter circuit into AC power, the power of the main DC power supply being smoothed by a DC filter capacitor, and the inverter being provided. In a power converter to be applied to a circuit, a discharge current of the DC filter capacitor is detected by a current detector, and when the discharge current detected by the current detector is in an increasing direction, a chopper control for controlling the voltage of the chopper circuit is performed. Circuit or a converter control circuit for controlling the voltage of the converter circuit is provided with a correction signal for decreasing the average value of the charging voltage of the regeneration capacitor according to the detection value of the current detector, and the current detection When the discharge current detected by the container is decreasing, the chopper control circuit or the converter Against motor control circuit, said current detector of the detection value power conversion device configured to provide a correction signal in the direction of increasing the average value of the charging voltage of the regenerative capacitor according to.