JP2014023310A - Converter system control method and control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device which, by actuating a PWM converter even at powering time, can ensure stable operation of the PWM converter at powering time and braking time and smooth transition of operation modes between powering and braking, without installing a DC current detector.SOLUTION: A converter system comprises a diode converter and a PWM converter 5 connected via a transformer 4 on the AC side to an AC power supply system N while being insulated from each other and, on the DC side, mutually connected in common to a load. In the converter system, a DC voltage 11 of the PWM converter 5 is obtained as a DC voltage detection value Vdc, an effective current component on the AC side of the PWM converter 5 is obtained as an effective current detection value Iq, and an effective current command value Iq* is generated on the basis of adjustment operation proportionate to a deviation between a DC voltage command value Vdc*2 equal to or greater than the full wave rectification peak voltage of the diode converter and the DC voltage detection value Vdc, and then limited to prescribed limiting values +IL1 and -IL1, whereby the PWM converter is operated by output of an effective current adjuster 14.

Description

  The present invention provides a converter system in which a diode converter and a PMW converter are insulated from each other by interposing a transformer on at least one of the alternating current sides and connected to an alternating current power supply system, and the direct current side is commonly connected to a load circuit. The present invention relates to a control method and a control device.

  FIG. 11 shows the main circuit configuration of this type of known converter system. A diode converter 2 is connected to an AC power supply system N via a transformer 1, and a DC side of the diode converter 2 is connected to a DC bus DC via a DC reactor 3 for smoothing a DC current. A load Z for power running / regenerative operation is connected to the DC bus DC. A PWM converter 5 is connected to the secondary side of the transformer 1 via another transformer 4, and the DC side of the PWM converter 5 is connected to the DC bus DC. In a typical converter system of this type, the PWM converter 5 is used as a regenerative converter, and the transformer 4 is used to convert the regenerative converter into a voltage suitable for regenerating power to the grid N. While the diode converter 2 exclusively supplies power to the load Z during power running operation, the diode converter 2 enters a blocking state due to the DC side voltage rising due to power regeneration from the load Z during regenerative operation. When the DC side voltage reaches a preset regeneration start voltage level, the PWM converter 5 becomes a regenerative converter and performs power regeneration to the system, thereby suppressing an increase in the DC side voltage.

  The output ratio of this type of conventional converter system is often 50% or less when the power running is 100%, and the regenerative converter is operated only at the time of regeneration. It is desirable to raise.

  A power converter that has an overload capability increased by operating a self-excited power converter that performs a regenerative operation at the time of power regeneration in parallel with a power diode rectifier is known (for example, Patent Document 1). . In this known device, in order to control the self-excited power converter, in addition to a DC voltage detector that detects a DC side voltage, a DC current detector (IL) that detects a DC current (IL) supplied to a load ( DCCT) is provided. Further, a changeover switch (SW) is provided to switch different control circuit routes between power running and regeneration according to the polarity of the load current detection value (IL) from the DC current detector (DCCT). . This change-over switch (SW) selects a control circuit route that commands the effective input current of the self-excited power converter by a current value proportional to the load current detection value (IL) during power running, and keeps the DC side voltage constant during regeneration. The control circuit route that commands the effective input current of the self-excited power converter is selected based on the voltage adjustment operation to be maintained at Therefore, this known converter system switches the operation mode of the self-excited power converter between power running and regeneration, and generates a command value for the effective input current during power running by using a direct current detector (DCCT). Must be used to detect the load current (IL).

JP 2005-318663 A

  It is an object of the present invention to operate a PWM converter as a self-excited power converter even during power running, and to achieve stable operation of the PWM converter during power running and regenerative (braking) and an operation mode between power running and regeneration. An object of the present invention is to provide a control method and a control apparatus for a converter system that realizes smooth mutual transition by simple means without detecting a load current with a DC current detector.

  As for the control method, the diode converter and the PMW converter are insulated from each other by interposing a transformer on at least one side on the AC side and connected to the AC power supply system, and are common to the load on the DC side. In the control method of the connected converter system, a DC voltage is obtained as a DC voltage detection value on the DC side of the PWM converter, and an effective current detection value having a polarity corresponding to the flow direction of the active power on the AC side of the PWM converter According to the flow direction of the active power based on the adjustment operation according to the voltage control deviation between the DC voltage command value corresponding to the voltage value equal to or higher than the full-wave rectification peak voltage of the diode converter and the DC voltage detection value An active current command value having a predetermined polarity is generated, and the active current command value is limited to a predetermined limit value. By generating a control signal for operating the PWM converter based on an adjustment operation according to an active current control deviation between the effective current command value to be limited and the active current detection value, the power running and regeneration in the PWM converter are generated. This is solved by a control method characterized in that the operation mode transition is performed based only on the change in polarity of the effective current command value.

  According to the control method of the present invention, the active current command value and the active current detection value have a polarity corresponding to the flow direction of the active power of the PWM converter. For example, positive polarity corresponds to the power running mode, and negative polarity corresponds to the regeneration mode. During powering in a low load state, DC voltage constant control is performed using a voltage value equal to or higher than the full-wave rectification peak voltage of the diode converter as a DC voltage command value, thereby preventing power supply by the diode converter and only by the PWM converter. Electric power is supplied. When the current limit operation region is entered as the load increases, the DC side voltage of the PWM converter is lowered in order to shift to the constant effective current control, whereby the PWM converter and the diode converter are operated in parallel. That is, the diode converter bears the excess load current exceeding the limit current level of the PWM converter. When the DC side voltage of the PWM converter rises due to regenerative power from the load side and the DC voltage detection value exceeds the DC voltage command value, the polarity of the effective current command value also turns negative due to the voltage control deviation turning negative. The control signal for operating the PWM converter based on the effective current adjustment operation shifts to the regeneration mode. During regeneration, the voltage constant control based on the adjustment operation according to the DC voltage command value and the DC voltage detection value set to a voltage value higher than the full-wave rectification peak voltage of the diode converter, and the inner loop as in power running With the current limit control by the effective current adjustment operation, the PWM converter operates in the regeneration mode and keeps the DC side voltage constant. Thus, according to the present invention, there is no need to change the control configuration between the power running mode and the regenerative mode, and without using a special switch for mutual transition between the modes. Power running and regenerative mode control is realized based only on the polarity of the effective current command value generated by the adjustment operation according to the voltage control deviation.

  In a preferred embodiment of the control method according to the present invention, the reactive current component is obtained as a reactive current detection value on the AC side of the PWM converter, and the reactive current control deviation between the reactive current command value given in advance and the reactive current detection value is determined. A control signal for operating the PWM converter is generated based on the adjustment operation according to the control signal, the control signal generated based on the adjustment operation according to the active current control deviation is a first component, and the control signal is generated according to the reactive current control deviation. A control signal generated based on the adjustment operation is used as a second component, and the first component and the second component are combined into a control signal for operating the PWM converter. The reactive current command value is fixed or variable, and at least a part of steady and / or transient reactive power fluctuations generated on the power supply system side can be compensated by the reactive power adjustment operation. Further, the first and second components can be given as orthogonal two-axis components based on the effective and ineffective directions of the system voltage vector. This orthogonal biaxial component is a DC amount signal, but can be converted into a gate pulse through an AC amount signal that can directly control the PWM converter by a known coordinate conversion technique.

  In another embodiment of the control method according to the present invention, the DC voltage command value is changed according to the voltage level detection value of the AC power supply system. In the case of a power supply system with a relatively small power supply capacity, a system voltage level rise exceeding the assumption may occur due to the sudden change of other loads connected to the power supply system, so the problem that occurs at that time is solved Is intended. If the DC voltage rises due to the power supply by the diode converter as the system voltage level rises, and the DC voltage detection value exceeds the DC voltage command value, it is generated by the adjustment operation according to the DC voltage control deviation. The PWM converter is shifted to the regeneration mode by reversing the polarity of the current command value. That is, even when the load is in a power running state, an operation may occur in which the diode converter supplies excess power exceeding the load demand and the PWM converter regenerates the excess power to the power supply system. As a result, the PWM converter may be overloaded. According to this embodiment, an undesired regenerative operation of such a PWM converter that is not based on a regenerative operation of the load is prevented. According to still another preferred embodiment, the DC voltage command value may be obtained by multiplying a fixed set value by a variable coefficient that changes according to a voltage level detection value of the AC power supply system.

  Furthermore, the said subject is connected to the AC power supply system by mutually insulating a diode converter and a PMW converter as a self-excited power converter by interposing a transformer on at least one side on the AC side, In the control system of the converter system that is connected to the load circuit in common on the DC side, the voltage detection means for obtaining the DC voltage as the DC voltage detection value on the DC side of the PWM converter and the effective current component on the AC side of the PWM converter are effective An effective current detection means for obtaining an effective current detection value having a polarity corresponding to the direction of power flow, a voltage command means for generating a DC voltage command value corresponding to a voltage value equal to or higher than the full-wave rectification peak voltage of the diode converter, and Active power based on the adjustment operation according to the control deviation between the DC voltage command value and the DC voltage detection value Voltage adjusting means for generating an effective current command value having polarity according to the flow direction, current limiting means for limiting the effective current command value to a predetermined limit value, the limited effective current command value, and An effective current adjusting means for generating a control signal for operating the PWM converter based on an adjusting operation according to a control deviation between the effective current detection value and a PWM converter based on the control signal from the effective current adjusting means This is solved by a control device for a converter system having PWM converter control means for generating a gate pulse.

  In a preferred embodiment of the control device according to the present invention, a reactive current detector means for obtaining a reactive current component as a reactive current detection value on the AC side of the PWM converter, a reactive current command value given in advance and the reactive current detection value Reactive current adjustment means for generating a control signal for operating the PWM converter based on an adjustment operation according to the reactive current control deviation between the PWM converter control means, the PWM converter control means for the adjustment operation according to the effective current control deviation The control signal generated based on the first component, the control signal generated based on the adjustment operation according to the reactive current control deviation is received as the second component, and the control signal obtained by combining the first component and the second component To generate a gate pulse for the PWM converter. The reactive current command value is fixed or variable, and at least a part of steady and / or transient reactive power fluctuations generated on the power supply system side can be compensated by the reactive power adjustment operation.

  In another embodiment of the control device according to the present invention, the voltage command means is configured to change the DC voltage command value in accordance with a voltage level detection value of an AC power supply system. As a result, the PWM converter can be prevented from shifting to an undesired regenerative mode due to an abnormal increase in the DC voltage that can occur in a power supply system having a relatively small power supply capacity. Furthermore, the voltage command means may be configured to obtain the DC voltage command value by multiplying a fixed set value by a variable coefficient that changes in accordance with a voltage level detection value of the AC power supply system.

  The features, advantages and details of other embodiments of the method and apparatus for controlling a converter system according to the invention will become apparent in the description of the exemplary embodiments with reference to the drawings and in the respective dependent claims.

  According to the converter system control method and the converter system according to the present invention, by causing the PWM converter to operate even during power running, the outflow of harmonics to the power supply system is reduced and the load current is detected as compared with the case where the diode converter is operated independently. Smooth operation between power running and regeneration based on the polarity of the effective current command value generated by the adjustment operation according to the voltage control deviation without providing a direct current detector or special operation mode changeover switch The mode transition is realized, and in any of the operation modes, a voltage adjustment loop having an effective current adjustment loop inside can be configured to stably operate the PWM converter.

It is a single line figure which shows the main circuit structure of the converter system of this invention. It is a block diagram which shows the 1st Example of the control structure of the converter system of this invention. It is a block diagram which shows the 2nd Example of the control structure of the converter system of this invention. It is a wave form diagram which shows the system side current of a diode converter. It is a wave form diagram which shows the synthetic system side current at the time of the parallel operation of a diode converter and a PWM converter. It is a characteristic view which shows the change of the PWM converter DC voltage depending on the load at the time of power running. It is a characteristic view which shows the change of the converter output depending on the load at the time of power running. It is a characteristic view which shows the relationship between DC voltage command value Vdc ^{* 2} and system voltage Vac in this invention. It is a figure explaining the flow of the active electric power at the time of power running in the converter system of this invention. It is a figure explaining the flow of the active electric power of the regeneration state in the converter system of this invention. It is a single line figure which shows the main circuit structure of the conventional converter system.

  Hereinafter, a converter system and a control method of the converter system according to the present invention will be described based on the embodiments of the present invention shown in the drawings. 1-4, the same code | symbol is attached | subjected to the same component as the conventional apparatus.

  According to the main circuit configuration of the converter system according to the present invention shown in FIG. 1, a diode converter 2 is connected to a three-phase AC power supply system N via a three-phase transformer 1, and the DC side of the diode converter 2 is a DC bus. Connected to DC. A DC reactor 3 is preferably connected between the diode converter 2 and the DC bus DC. A load Z is connected to the DC bus DC. A PWM converter 5 is connected to the secondary side of the three-phase transformer 1 via another three-phase transformer 4, and the DC side of the PMW converter 5 is connected to the DC bus DC. It is preferable to connect the smoothing capacitor 6 to the DC side of the PWM converter 5 and connect the filter circuit 7 and the AC reactor 8 between the transformer 4 and the PWM converter 5.

  The diode converter 2 is composed of, for example, a three-phase bridge connection of diodes. The PWM converter 5 includes a three-phase bridge connection of power semiconductor elements, for example, IGBT elements each having an antiparallel diode. The transformer 1 is used to convert the system voltage into a voltage suitable for the diode converter, and the transformer 4 is used to insulate and connect the AC side of the PWM converter 5 and the diode converter 2 to each other. The smoothing capacitor 6 is used to smooth the DC side voltage of the PWM converter 5, and the DC reactor 3 is used to smooth the output current of the diode converter 2. The filter circuit 7 operates to suppress the harmonic current output from the PWM converter 5. The AC reactor 8 is a step-up reactor for obtaining a predetermined DC voltage by the switching operation of the PWM converter 5. The load Z includes a power running and regenerative operation load, for example, an inverter-fed variable speed AC motor.

FIG. 2 shows a block diagram of an embodiment of the control device according to the invention. Between the DC terminals to which the smoothing capacitor 6 of the PWM converter 5 is connected, the DC voltage detection value Vdc is taken out by the DC voltage detector 11 and guided to the input part of the DC voltage regulator 12. The DC voltage regulator 12 determines a voltage control deviation (Vdc ^{* 2−} Vdc) by matching the given DC voltage command value Vdc ^{* 2} and the DC voltage detection value Vdc at the input unit, and determines the voltage control deviation. The active current command value Iq ^* is generated based on the corresponding adjustment operation, that is, by performing, for example, a proportional integration operation on the voltage control deviation. The output of the DC voltage regulator 12 is limited. The effective current command value Iq ^* output from the DC voltage regulator 12 has a polarity, and limit values + I _L1 and −I _L2 can be set separately for each polarity.

An AC input current of the PWM converter 5 is separated into a reactive current component Id and an active current component Iq and detected by a current detection circuit 13 including a current transformer inserted on the AC side of the PWM converter 5. This separation is performed based on a system voltage synchronization signal (not shown) detected on the AC side. The effective current detection value Iq and the reactive current detection value Id have polarity. For example, the flow of active power from the system side to the PWM converter side is selected as positive polarity, and the reverse flow is selected as negative polarity. Therefore, the positive polarity of the effective current detection value Iq and the effective current command value Iq ^* corresponds to the power running mode, and the negative polarity corresponds to the regeneration mode. For this reason, the mutual transition between the power running mode and the regenerative mode of the PWM converter is automatically performed based on the polarity of the effective current command value generated by the adjustment operation according to the DC voltage control deviation.

The active current adjuster 14 matches the effective current command value Iq ^* and the effective current detection value Iq at the input portion to obtain an effective current control deviation (Iq ^* −Iq), and is based on an adjustment operation according to the effective current control deviation. That is, a control signal for operating the PWM converter 5 is generated as a first component by performing, for example, a proportional integration operation on the control deviation. Similarly, the reactive current regulator 15 obtains a reactive current control deviation (Id ^* −Id) from the reactive current command value Id ^* and the reactive current detection value Id, and based on the adjusting operation according to the reactive current control deviation, that is, A control signal for operating the PWM converter 5 is generated as a second component by performing, for example, a proportional integration operation on the control deviation.

  In the control unit 16 of the PWM converter 5, the first component (q-axis component) from the active current regulator 14 and the second component (d-axis component) from the reactive current regulator 15 are combined to finally form a gate pulse. Converted. Therefore, in this embodiment, the coordinate converter 17 converts the d-axis component and the q-axis component into a two-phase AC amount signal based on a system voltage synchronization signal (not shown). The signal is converted into a three-phase alternating current signal by the phase converter 18 and then input to the gate pulse generation circuit 19. The gate pulse generation circuit 19 outputs a gate pulse signal pulse-shaped by PWM modulation to the PWM converter 5. The power semiconductor element of the PWM converter 5 is switched according to the gate pulse signal.

Thus, according to the present invention, there is no need to change the control configuration between the power running mode and the regenerative mode, and without using a special switch for mutual transition between the modes. Power running and regenerative mode control is realized based only on the polarity of the effective current command value generated by the adjustment operation according to the voltage control deviation.

FIG. 6 shows the course of the DC voltage Vdc depending on the load (effective current Iq) during power running, and FIG. 7 shows the total output P (power supplied to the diode converter) of both converters depending on the load (active current Iq) during power running. It shows the course of P the sum of the supply power _{P 5} of ₂ and PWM converter). During powering in a low load state, DC voltage constant control (see region (a) in FIG. 6) is performed with a voltage value higher than the full-wave rectification peak voltage of the diode converter 2 as the DC voltage command value Vdc ^{* 2} . Thus, the power supply from the diode converter 2 is blocked, and the power supply is performed only by the PWM converter 5 (see region (a) in FIG. 7). When the active current command value Iq ^* enters the current limiting operation region limited to the limiting value + _IL1 as the load increases, the DC side voltage Vdc of the PWM converter 5 decreases to shift to constant effective current control (FIG. 6). Thus, the PWM converter 5 and the diode converter 2 are operated in parallel (see the region (b) in FIG. 7). That is, the diode converter 2 supplies the excess load current exceeding the limit current level of the PWM converter 5.

  According to the present invention, the parallel operation of the PWM converter 5 and the diode converter 2 can be expected to reduce the lower harmonic components of the harmonics compared to the operation using only the diode converter 2. That is, in the case of operation using only the diode converter 2, the current flows in the waveform side in FIG. 4 on the system side, whereas the current waveform on the system side in the parallel operation of the PWM converter 5 and the diode converter 2 is as shown in FIG. become. 4 and 5, the horizontal axis represents time t, and the vertical axis represents the instantaneous current value iac.

In the parallel operation of the diode converter 2 and the PWM converter 5 during power running described above, the flow of active power from the system N to the load Z is as shown by a thick arrow line in FIG. However, since the diode converter 2 rectifies the system voltage and outputs a DC voltage, the DC voltage value increases as the system voltage rises. As a result, the DC voltage detection value Vdc becomes the DC voltage command value Vdc ^{* 2} . If exceeded, the polarity of the active current command value Iq ^* generated based on the adjustment operation according to the voltage control deviation (Vdc ^{* 2-} Vdc) turns negative, and the PWM converter 5 shifts to the operation in the regeneration mode. Therefore, as indicated by a thick arrow line in FIG. 10, the diode converter 2 takes out excess power exceeding the load demand from the system, and the PWM converter 5 always regenerates the excess power to the system. In the case of a power supply system with a relatively small power supply capacity, an abnormal increase of the DC side voltage more than expected can occur. In such a case, the PWM converter 5 may be overloaded by an undesired regenerative operation, so a countermeasure is necessary.

  FIG. 3 shows a main part of an embodiment of the control device according to the present invention in which the countermeasure is taken. According to this, the instrument transformer 20 is connected to the primary side of the transformer 4, and the three-phase system voltage detected by the transformer 20 is converted into a two-phase system voltage by the three-phase to two-phase converter 21. Converted to a signal. The system voltage signal of the two-phase amount of the three-phase to two-phase converter 21 is converted into a direct current amount by the coordinate converter 22. In the embodiment shown in FIG. 3, the instrument transformer 20, the 3-phase to 2-phase converter 21 and the coordinate converter 22 are not newly added components, but a phase reference for controlling the PWM converter. In order to derive a system voltage synchronization signal that gives

The system voltage level detection value Vac as the DC amount is preferably set to a level that does not cause an overvoltage or undervoltage of the PWM converter within the actual system voltage fluctuation range after passing through the noise elimination filter 23. The value may be limited to the value Vac _max and the system voltage compensation lower limit value Vac _min , and further divided by the system voltage compensation lower limit value Vac _min in the divider 24 to be converted into a unit amount.

In this embodiment, the DC voltage command value Vdc ^{* 2 that} is matched with the DC voltage detection value Vdc from the DC voltage detector 11 at the input portion of the DC voltage regulator 12 is a fixed DC voltage command value Vdc ^* given in advance in this embodiment ^{. 1} is generated by coefficient correction by the multiplier 25. That is, after the system voltage level detection value Vac is converted into a unit amount based on the system voltage compensation lower limit value Vac _min , the initial DC voltage command value Vdc given as a fixed set value in the multiplier 25 as a coefficient input. ^* Multiply by ¹ . Therefore, when the voltage level detection value Vac of the system is within the limits of the limit values Vac _max and Vac _min , the DC voltage command value Vdc ^{* 2} input to the DC voltage regulator 12 is
_{^{Vdc * 2 = (Vac / Vac}} min) · Vdc * 1 (1)
It becomes. Therefore, the DC voltage command value Vdc ^{* 2} is corrected as shown in FIG. 8 depending on the fluctuation of the system voltage Vac.

In this way, the DC voltage command value Vdc ^{* 2} input to the DC voltage regulator 12 is corrected according to the fluctuation amount of the voltage level detection value Vac of the system, so that the DC voltage command value Vdc ^{* 2} is always converted to the diode converter 2. Can be maintained at a voltage value equal to or higher than the full-wave rectification peak voltage. Therefore, it is possible to prevent the PWM converter 5 from performing a regenerative operation even during power running. That is, it is possible to always keep the flow of active power in the state shown in FIG. 9 during parallel operation during power running and prevent the flow of active power from being in the state shown in FIG.

The upper limit of the DC voltage is limited to a certain level due to the limit of the cutoff capability of the IGBT element. Even if the upper limit of the DC voltage command value Vdc ^{* 2} is determined by the system voltage compensation upper limit value Vac _max , the actual DC voltage Vdc may reach the above limit level due to an abnormality in the system side or the load side or the converter system itself. obtain. When the limit level is reached, the operation of the PWM converter is stopped and other protection means are activated to protect the device.

  In the embodiment of FIG. 3, the contents shown and described in the embodiment of FIG. 2 are valid for the configuration and operation of the subsequent stage after the voltage regulator 12 except for the above description. Illustration and detailed description are omitted.

DESCRIPTION OF SYMBOLS 1 Transformer 2 Diode converter 3 DC reactor 4 Transformer 5 PWM converter 6 Smoothing capacitor 7 Filter circuit 8 AC reactor 11 DC voltage detector 12 DC voltage regulator 13 Current detection circuit 14 Active current regulator 15 Invalid current regulator 16 PWM Converter control unit 17 Coordinate converter 18 Two-phase to three-phase converter 19 Gate pulse generator 20 Instrument transformer 21 Three-phase to two-phase converter 22 Coordinate converter 23 Noise removal filter 24 Divider 25 Multiplier DC DC bus N AC power supply system Z Load

Claims (14)

  In the control method of the converter system in which the diode converter and the PMW converter are insulated from each other by interposing a transformer on at least one side on the alternating current side and connected to the alternating current power supply system, and commonly connected to the load on the direct current side. Full-wave rectification of the diode converter by obtaining a DC voltage as a DC voltage detection value on the DC side of the PWM converter and obtaining an active current component as an effective current detection value having a polarity corresponding to the flow direction of the active power on the AC side of the PWM converter An effective current command value having a polarity corresponding to the flow direction of the active power based on an adjustment operation according to a voltage control deviation between the DC voltage command value corresponding to a voltage value equal to or higher than the peak voltage and the DC voltage detection value. The active current command value is limited to a predetermined limit value, and the limited effective current command value and the By generating a control signal for operating the PWM converter based on the adjustment operation according to the active current control deviation between the active current detection value and the active current in the PWM converter, the operation mode transition between the power running and the regeneration is the active current. A control method for a converter system, wherein the control method is performed only based on a change in polarity of a command value.   The reactive current component is obtained as a reactive current detection value on the AC side of the PWM converter, and the PWM converter is adjusted based on an adjustment operation according to the reactive current control deviation between the reactive current command value given in advance and the reactive current detection value. A control signal to be operated is generated, the control signal generated based on the adjustment operation according to the active current control deviation is a first component, and the control signal generated based on the adjustment operation according to the reactive current control deviation is 2. The converter system control method according to claim 1, wherein the control signal is a control signal for operating the PWM converter by combining the first component and the second component into two components.   3. The converter system control method according to claim 1, wherein the DC voltage command value is changed according to a voltage level detection value of an AC power supply system.   4. The converter according to claim 1, wherein the DC voltage command value is obtained by multiplying a fixed set value by a variable coefficient that changes in accordance with a voltage level detection value of the AC power supply system. How to control the system.   5. The converter system control method according to claim 1, wherein a smoothing reactor is connected in series on the DC side of the diode converter.   6. The method of controlling a converter system according to claim 1, wherein a smoothing capacitor is connected in parallel to the DC side of the PWM converter.   7. The method of controlling a converter system according to claim 1, wherein an AC reactor and / or a filter circuit is connected to the AC side of the PWM converter.   In a control device of a converter system in which a diode converter and a PMW converter are insulated from each other by interposing a transformer on at least one side on the AC side and connected to an AC power supply system, and are connected to a load circuit in common on the DC side. , A voltage detection means for obtaining a DC voltage as a DC voltage detection value on the DC side of the PWM converter, and an effective for obtaining an effective current detection value having a polarity corresponding to the flow direction of active power on the AC side of the PWM converter Current detection means, voltage command means for generating a DC voltage command value corresponding to a voltage value equal to or higher than the full-wave rectification peak voltage of the diode converter, and a control deviation between the DC voltage command value and the DC voltage detection value Generates an active current command value having a polarity corresponding to the flow direction of the active power based on the adjustment operation Voltage adjusting means, current limiting means for limiting the effective current command value to a predetermined limit value, and adjusting operation according to a control deviation between the limited effective current command value and the effective current detection value And an effective current adjusting means for generating a control signal for operating the PWM converter based on the control signal, and a PWM converter control means for generating a gate pulse for the PWM converter based on the control signal from the effective current adjusting means. A control device for the converter system.   Reactive current detector means for obtaining a reactive current component as a reactive current detection value on the AC side of the PWM converter, and an adjustment operation according to a reactive current control deviation between the reactive current command value given in advance and the reactive current detection value And a reactive current adjusting means for generating a control signal for operating the PWM converter based on the control signal, wherein the PWM converter control means uses the control signal generated based on the adjusting operation according to the effective current control deviation as a first component. The control signal generated based on the adjustment operation according to the reactive current control deviation is received as a second component, and the gate pulse for the PWM converter is generated based on the control signal obtained by synthesizing the first component and the second component. 9. The converter system control device according to claim 8, wherein the controller is generated.   10. The control device for a converter system according to claim 8, wherein the voltage command means is configured to change the DC voltage command value according to a voltage level detection value of an AC power supply system.   The voltage command means is configured to obtain the DC voltage command value by multiplying a fixed set value by a variable coefficient that changes according to a voltage level detection value of the AC power supply system. Item 11. The control device for the converter system according to one of Items 8 to 10.   12. The control device for a converter system according to claim 8, wherein a smoothing reactor is connected in series on the DC side of the diode converter.   13. The converter system control device according to claim 8, wherein a smoothing capacitor is connected in parallel to the DC side of the PWM converter.   14. The converter system control device according to claim 8, wherein an AC reactor and / or a filter circuit is connected to the AC side of the PWM converter.

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