JP2003230280A - Power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power converter capable of suppressing an eddy current in short-circuiting a load while keeping a power factor of a voltage-type inverter high in feeding power to the load by utilizing impedance phenomena of a capacitive impedance and an inductive impedance. <P>SOLUTION: The power converter comprises: the voltage-type inverter 2 that converts a DC voltage to a square-wave AC by on/off-controlling a switching element; and an impedance circuit that is formed of the inductive impedance 3 and the capacitive impedance 4 that are connected in series between output terminals of the voltage-type inverter 2, and forms a series resonance circuit using the inductive impedance 3, the capacitive impedance 4 and the load 5 with both ends of the capacitive impedance 4 as connecting ends. The voltage-type inverter 2 outputs an AC of a frequency proximate to a resonance frequency of a series resonance circuit. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention utilizes the resonance phenomenon of capacitive impedance and inductive impedance to, for example, a capacitive load such as an ozone generator or an inductive load or a resistive load such as a high frequency heating furnace. The present invention relates to a power converter that supplies power.

[0002]

2. Description of the Related Art For example, since an ozone generator is a load having a capacitive impedance, two power supply systems are adopted. One of them is a current source converter in which the AC current waveform does not change when the power factor of the AC load is changed.
The other is a voltage source converter whose AC voltage waveform does not change when the power factor of the AC load is changed. FIG. 12 shows an application example of the voltage source converter disclosed as an ozonizer device in Japanese Patent Laid-Open No. 9-2806. In the figure, the voltage source inverter 101 supplies a rectangular wave voltage. The primary winding of the transformer 102 is connected to the output terminal of the voltage source inverter 101. The secondary winding of the transformer 102 is connected in parallel to an inductive impedance 104 and a capacitive impedance 105, which are connected in parallel, and further connected in parallel to an ozonizer 106 as a load, and is connected to a filter 103 having an overall filter function. ing.

Here, the voltage source inverter 101 outputs a rectangular wave voltage having an amplitude of E. The transformer 102 boosts this voltage according to the primary and secondary turns ratio. Filter 103
, The inductance L of the inductive impedance 104 and the capacitance C of the capacitive impedance 105
A parallel resonance circuit is formed by the capacitance Cs of the ozonizer 106, and the voltage source inverter 101 outputs a rectangular wave voltage having a frequency close to its resonance frequency. This causes a sinusoidal voltage to be applied across the ozonizer 106.

[0004]

As shown in FIG. 12, in a power converter in which an inductive impedance 104 and a capacitive impedance 105 are connected in parallel to form a resonance circuit, when a load is short-circuited, Type inverter 1
There is a problem that an excessive current flows because there is only leakage impedance of the transformer 102 as an element for suppressing the rising of the current of 01.

The present invention has been made to solve the above problems, and utilizes the resonance phenomenon of the capacitive impedance and the inductive impedance to supply the power to the load, thereby increasing the power factor of the voltage source inverter. While keeping high
An object of the present invention is to provide a power conversion device capable of suppressing overcurrent when a load is short-circuited.

[0006]

The invention according to claim 1 is
By controlling the switching element on / off, a voltage source inverter that converts a DC voltage into a square wave alternating current and outputs it, and an inductive impedance and a capacitive impedance connected in series between the output terminals of the voltage source inverter. And a impedance circuit that forms a series resonance circuit by the inductive impedance, the capacitive impedance and the load, with both ends of the capacitive impedance as the connection terminals of the load, and the voltage source inverter has a frequency close to the resonance frequency of the series resonance circuit. It is a power converter that outputs the alternating current.

According to a second aspect of the present invention, in the power converter according to the first aspect, the primary winding is connected between the output terminals of the voltage source inverter, and the inductive impedance and the capacitance are provided between the terminals of the secondary winding. This is provided with a transformer in which the sex impedance is connected in series.

According to a third aspect of the present invention, in the power converter according to the first aspect, the primary winding is connected in series with the inductive impedance between the output terminals of the voltage source inverter, and the secondary winding has a capacitance. It has a transformer in which the characteristic impedance is connected in series.

According to a fourth aspect of the present invention, in the power conversion device according to any one of the first to third aspects, the current detecting means for directly or indirectly detecting the output current of the voltage type inverter, and the voltage type Voltage detection means for detecting the output voltage of the inverter, reactive power detection means for detecting the output reactive power of the voltage-type inverter based on the output current signal of the current detection means and the output voltage signal of the voltage detection means, and the detected reactive power And a reactive power control means for adjusting the output frequency of the voltage source inverter so that the power is minimized.

According to a fifth aspect of the present invention, in the power converter according to any one of the first to third aspects, the current detecting means for directly or indirectly detecting the output current of the voltage type inverter, and the voltage type A signal generating means for generating a reactive power detection signal whose phase is delayed by 90 degrees with respect to the output voltage of the voltage source inverter based on an on / off control signal for a switching element forming the inverter, and an output current of the current detecting means Reactive power detection means for detecting the output reactive power of the voltage type inverter based on the signal and the reactive power detection signal of the signal generation means, and adjusting the output frequency of the voltage type inverter so that the detected reactive power is minimized. And a reactive power control means.

According to a sixth aspect of the present invention, in the power conversion device according to any one of the first to fifth aspects, the current detecting means for directly or indirectly detecting the output current of the voltage type inverter, and the voltage type Voltage detection means for directly or indirectly detecting the output voltage of the inverter; and active power detection means for detecting the output active power of the voltage source inverter based on the output current signal of the current detection means and the output voltage signal of the voltage detection means. And an active power control means for adjusting the output voltage of the voltage source inverter so that the detected active power becomes equal to the active power command value.

According to a seventh aspect of the present invention, in the power conversion device according to any one of the first to fifth aspects, the current detecting means for directly or indirectly detecting the output current of the voltage type inverter, and the voltage type A signal generating means for generating an active power detection signal synchronized with the output voltage of the voltage source inverter based on an on / off control signal for a switching element forming the inverter; and an output current signal and a signal generating means of the current detecting means. Active power detecting means for detecting the output active power of the voltage inverter based on the active power detection signal, and active power for adjusting the output voltage of the voltage inverter so that the detected active power becomes equal to the active power command value. And a control means.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail based on the preferred embodiments shown in the drawings.

FIG. 1 is a circuit diagram showing the configuration of a first embodiment of a power conversion device according to the present invention. In the figure, 1A is a power converter, which is connected in series between a voltage source inverter 2 in which switching elements such as IGBTs are bridge-connected, and a diode is connected in antiparallel to each switching element, and an output terminal of the voltage source inverter 2. And an impedance circuit composed of the generated inductive impedance 3 and capacitive impedance 4. In this impedance circuit, both ends of the capacitive impedance 4 are connected to the load 5, and when the load is capacitive such as an ozone generator, the inductance of the inductive impedance 3 and
The capacitance of the capacitive impedance 4 and the capacitance of the load 5 form a series resonance circuit. The voltage source inverter 2 generates a rectangular wave voltage having a frequency close to the resonance frequency of the series resonance circuit. This causes the series resonant circuit to resonate and the reactive power to circulate between the inductive impedance 3 and the capacitive impedance 4.

With such a configuration, the voltage-source inverter 2 only needs to supply the active power consumed by the resistance of the load 5, and the inverter output can be increased in power factor. Further, due to the resonance of the series resonance circuit, it is possible to supply the load 5 with a high voltage that is twice as high as the voltage output from the voltage source inverter 2. Further, since the inductive impedance 3 exists between the voltage source inverter 2 and the load 5, even when the load 5 is short-circuited, the overcurrent of the voltage source inverter 2 due to a failure can be suppressed.

FIG. 2 is a circuit diagram showing the configuration of the second embodiment of the power conversion device according to the present invention. In the figure, the same elements as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In the power converter 1B according to this embodiment, the primary winding of the transformer 6 is connected between the output terminals of the voltage source inverter 2, and the secondary winding of the transformer 6 has an inductive impedance 3 and a capacitive impedance 4. Are connected in series, and both ends of the capacitive impedance 4 are connected to the load 5.

With this configuration, the output voltage of the voltage source inverter 2 can be converted into a value required for the load 5, and the voltage and current rating of the voltage source inverter 2 can be selected most economically. The insulation performance between the voltage source inverter 2 and the load 5 can be improved.

FIG. 3 is a circuit diagram showing the configuration of a third embodiment of the power conversion device according to the present invention. In the figure, the same elements as those in FIG. 2 are designated by the same reference numerals and their description is omitted. To do. The power converter 1C according to this embodiment is the same as the transformer 6 described above.
2 is different from that of FIG. 2 in that is connected between the inductive impedance 3 and the capacitive impedance 4. That is, the inductive impedance 3 and the primary winding of the transformer 6 are connected in series between the output terminals of the voltage source inverter 2, and the capacitive impedance 4 is connected in series to the secondary winding of the transformer 6, A series resonance circuit is formed by the inductive impedance 3, the capacitive impedance 4, and the load 5 including the transformer 6.

The ozone generator, which is a capacitive impedance, needs to apply a voltage of several kV to 10 kV. In this case, the primary winding of the transformer 6 is connected to the inductive impedance 3
The voltage on the primary winding side of the transformer 6 can be suppressed to a low level by connecting in series with the output terminals of the voltage source inverter 2. As a result, the size of the entire device including the size of the transformer 6 can be reduced.

FIG. 4 is a circuit diagram showing the configuration of a fourth embodiment of the power conversion device according to the present invention. In the figure, the same elements as those in FIG. 3 are designated by the same reference numerals and their description is omitted. To do. The power conversion device 1D according to this embodiment has a large output capacity of a power source and is applied to a case where a plurality of inverters (only two are shown in FIG. 4) are connected in parallel, and a voltage source inverter 2A is used. One end of the inductive impedance 3A is connected to one end of the output terminal of the
One end of the inductive impedance 3B is connected to one end of the output terminal of B, the other ends of these inductive impedances 3A and 3B are connected to one end of the primary winding of the transformer 6, and the other end of the primary winding is connected. Is connected to each of the other ends of the voltage source inverters 2A and 2B.

In general, when voltage source inverters are connected in parallel, a reactor for balancing the parallel connected inverters may be required. By adopting the configuration shown in FIG. 4, the inductive impedances 3A and 3B forming the series resonance circuit can also have the function of the reactor.

FIG. 5 is a circuit diagram showing the configuration of a fifth embodiment of the power conversion device according to the present invention. In the figure, the same elements as those in FIG. 2 are designated by the same reference numerals and their description is omitted. To do. The power converter 1E according to this embodiment differs from that of FIG. 2 in that a function for controlling reactive power is provided. That is, in order to control the reactive power, the output voltage of the voltage source inverter 2 is detected by the voltage detector 7, and the output current of the voltage source inverter 2 is detected by the current detector 8. And
Based on the voltage detection signal and the current detection signal, the reactive power detection circuit 60 detects the reactive power of the circuit elements including the transformer 6 and the load 5, and adds the reactive power detection value 61 to the reactive power control circuit 50. The reactive power control circuit 50 outputs an output frequency command value 51 that minimizes the reactive power detection value 61.

As described above, when the circuit including the leakage impedance of the transformer 6, the inductive impedance 3, the capacitive impedance 4 and the load 5 is in a resonance state,
The power factor of the voltage source inverter 2 becomes high. However,
The resonance frequency also fluctuates due to manufacturing errors and characteristic fluctuations of the transformer 6, the inductive impedance 3, the capacitive impedance 4, and the load 5. In the present embodiment, in order to suppress the reactive power that increases due to the variation of the resonance frequency and improve the power factor,
The output frequency of the voltage source inverter 2 is controlled so that the reactive power is minimized.

In the fifth embodiment shown in FIG. 5,
Although the output current of the voltage source inverter 2 is directly detected on the primary winding side of the transformer 6, even if it is indirectly detected on the secondary side of the transformer 6 or the output section of the power converter 1E, The reactive power control can be performed in the same manner as described above, and thereby the power factor can be improved.

FIG. 6 is a circuit diagram showing the configuration of a sixth embodiment of the power conversion device according to the present invention. In the figure, the same elements as those in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted. To do. The power converter 1F according to this embodiment is different from FIG. 5 only in that the voltage detector 7 is provided on the secondary winding side of the transformer 6 in order to control the reactive power. It is configured exactly the same as 5.

Even with this configuration, when the leakage impedance of the transformer 6 is smaller than that of the inductive impedance 3, the same effect as that of the embodiment shown in FIG. 5 can be obtained.

FIG. 7 is a circuit diagram showing the configuration of a seventh embodiment of the power conversion device according to the present invention. In the figure, the same elements as those in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted. To do. The power converter 1G according to this embodiment differs from that in FIG. 5 in that a reactive power detection signal generator 70 is provided instead of the voltage detector 7 for controlling the reactive power.

FIG. 8 is a circuit diagram showing the configuration of an eighth embodiment of the power converter according to the present invention. The current detector 8 shown in FIG. 7 detects the secondary winding current of the transformer 6. Figure 7
And the configuration is different. In the power converter 1H shown in FIG. 8, the reactive power detection signal generator 7 is used.
In order to explain the principle of 0, the detailed configuration of the voltage source inverter 2 is shown in a circuit diagram, and the connection relationship of the inductive impedance 3 and the capacitive impedance 4 with respect to the secondary winding of the transformer 6 is shown in detail. It is a thing.

Here, the power converter 1G shown in FIG. 7 uses a reactive power detecting signal generator 70 in place of the voltage detector 7 shown in FIG. 5, and the power converter shown in FIG. The device 1H uses a reactive power detection signal generator 70 in place of the voltage detector 7 shown in FIG. 6, and is otherwise configured the same as the power conversion device 1E or 1F. Therefore, the principle of the reactive power detection signal generator 70 will be described with reference to the detailed circuit diagram of FIG. 8 and the time chart of FIG.

The voltage source inverter 2 is, as shown in FIG.
A series connection circuit of switching elements Q1 and Q2 such as an IGBT and a series connection circuit of switching elements Q3 and Q4 are connected in parallel, and a DC power supply V
DC is connected. Switching elements Q1 and Q2
The primary winding of the transformer 6 is connected between the interconnection point of the transformer 6 and the interconnection point of the switching elements Q3 and Q4. A series connection circuit of the inductive impedance 3 and the capacitive impedance 4 is connected to both ends of the secondary winding of the transformer 6. The switching elements Q1, Q2, Q
Diodes for freewheeling are connected in antiparallel to 3 and Q4, respectively.

In the voltage source inverter 2, the switching elements Q1 and Q2 connected in series do not turn on at the same time as shown in FIG.
Switching elements Q3 and Q4, as shown in FIG.
It does not turn on at the same time. Further, while the switching elements Q1 and Q4 are in the ON state, the positive voltage Vinv is generated across the primary winding of the transformer 6, and the transformer 6 is in the ON state while the switching elements Q2 and Q3 are in the ON state. A negative voltage Vinv is generated at both ends of the primary winding. Therefore, this voltage Vinv is equal to Vin shown in FIG.
It changes like v. Reactive power detection signal generator 70
Is a voltage signal Vinv90 whose phase is delayed by 90 degrees from the voltage Vinv based on the phase difference and frequency of the ON / OFF control signals for the switching elements Q1 to Q4 (FIG. 9).
(Refer to FIG. 3) is generated and added to the reactive power detection circuit 60. At this time, a signal having a pulse width corresponding to the phase difference may be output with a delay of 1/4 cycle of the frequency command value.

It should be noted that the reactive power detection circuit 60 does not control the reactive power to a constant value but may be operated so as to make the reactive power as small as possible, and the reactive power detection needs to be accurate as an absolute amount. Absent. Therefore, as shown by VQ in FIG. 9, there is no problem even with a signal waveform that does not accurately reflect the pulse width of the voltage.

Thus, according to the seventh embodiment shown in FIG. 7 and the eighth embodiment shown in FIG. 8, by using the reactive power detection signal generator 70, for example, a voltage for high voltage is used. A new effect is obtained in that the detector 7 can be eliminated.

FIG. 10 shows a ninth embodiment of the power conversion device according to the present invention.
9 is a circuit diagram showing a configuration of the embodiment of the present invention. In the figure, the same elements as those of FIG.
The power converter 1J shown in FIG. 10 controls active power to a preset value and simultaneously controls reactive power to the minimum. In this case, the current detector 8 is connected to the path connecting the voltage source inverter 2 and the primary winding of the current detector 8.
Is provided, and the voltage detector 7 is provided on the path connecting the load 5 to both ends of the capacitive impedance 4. Then, the current detection signal is applied to both the reactive power detection circuit 60 and the active power detection circuit 80, and the voltage detection signal is applied to the active power detection circuit 80. Further, the reactive power detection signal of the reactive power detection signal generator 70 described above is added to the reactive power detection circuit 60.

Here, the reactive power detection circuit 60 multiplies the current detection signal from the current detector 8 and the reactive power detection signal to calculate the reactive current, and when the output of the voltage source inverter 2 is a single phase. In order to reduce the increased ripple component, the reactive power detection value 61 is output via the low pass filter 62. The reactive power detection value 61 output from the reactive power detection circuit 60 is compared with a set value of zero by the reactive power control circuit 50, and an output frequency command value 51 that minimizes the deviation is output here. To be done.

On the other hand, the active power detection circuit 80 multiplies the voltage detection signal from the voltage detector 7 and the current detection signal from the current detector 8 to calculate active power, and then the output of the voltage source inverter 2 The active power detection value 81 is output via the low-pass filter 62 in order to reduce the amount of ripple that increases in the case of a single phase. The active power detection value 81 output from the active power detection circuit 80 is the active power control circuit 90.
Active power setting value (Pref) 9 preset by
The inverter pulse width command value 93 which is compared with 1 to set the deviation to zero is output here, and the phase difference φ shown in the time chart of FIG. 9 is controlled.

Next, the reactive power detection signal generator 70 outputs the output frequency command value 51 and the inverter pulse width command value 93.
A reactive power detection signal is generated based on the above, and applied to the reactive power detection circuit 60.

Thus, according to the ninth embodiment shown in FIG. 10, the output frequency of the voltage source inverter 2 is controlled so that the reactive power is minimized, and the voltage source is controlled so that the active power matches the set value. Since the pulse width of the inverter 2 is controlled, it is possible to constantly improve the power factor of the voltage source inverter 2 while controlling the output active power. As a result, the capacity of the voltage source inverter is reduced and the capacity of the transformer is reduced. It is possible to reduce the power consumption and provide an economical power conversion device.

Further, since the inductive impedance 3 is connected to the load 5 in series, even if the load is short-circuited, the rise of the fault current can be suppressed and overcurrent protection becomes possible. Although the current detector 8 is provided on the primary winding side of the transformer 6 in the ninth embodiment shown in FIG. 10, it may be provided on the secondary winding side of the transformer 6 in a substantially similar manner. The effect is obtained.

FIG. 11 shows the first embodiment of the power conversion device according to the present invention.
10 is a circuit diagram showing a configuration of an embodiment of No. 0, and FIG.
The same elements as those of the ninth embodiment shown in are attached with the same notations and an explanation thereof will be omitted. The power conversion device 1K shown here is one in which the voltage detector 7 in FIG. 10 is removed and an active power detection signal generator 71 is provided in its place. As described above, the output voltage of the voltage source inverter 2 is as shown in FIG.
As described with reference to the time chart of, the calculation can be performed based on the ON / OFF control signal for the switching element forming the voltage inverter, that is, the gate waveform. The active power detection signal generator 71 generates the voltage Vi generated in the primary winding of the transformer 6 based on this gate waveform.
Calculate and output nv.

Among the above, the active power calculated based on the output voltage waveform of the voltage source inverter 2 and the active power calculated based on the output voltage waveform of the power converter 1J or 1K are the transformer 6 and the inductive property. Only the loss of impedance 3 is different. This loss is usually 3% or less. If these losses are negligible in terms of control, the voltage active power detection signal generator 71 calculates the output voltage of the voltage source inverter 2. However, substantially the same control as detecting the output voltage of the power converter 1J or 1K by the voltage detector 7 can be performed.

Thus, according to the tenth embodiment, when a high voltage is output as in the power supply device for an ozone generator, the voltage detector for the high voltage can be omitted and economical power consumption can be achieved. A conversion device can be provided.

Although each of the above-described embodiments has been described with respect to the case where AC power is supplied to a capacitive load such as an ozone generator, the present invention is not limited to this and the inductive property is not limited thereto. It can be applied whether it is a load or a resistive load.

[0044]

As is apparent from the above description, according to the present invention, the inductive impedance and the capacitive impedance are connected in series between the output terminals, and both ends of the capacitive impedance are connected to the load, Since the series resonant circuit is formed by the capacitive impedance, the capacitive impedance, and the load, it is possible to suppress the overcurrent when the load is short-circuited while maintaining a high power factor.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a first embodiment of a power conversion device according to the present invention.

FIG. 2 is a circuit diagram showing a configuration of a second embodiment of a power conversion device according to the present invention.

FIG. 3 is a circuit diagram showing a configuration of a third embodiment of a power conversion device according to the present invention.

FIG. 4 is a circuit diagram showing a configuration of a fourth embodiment of a power conversion device according to the present invention.

FIG. 5 is a circuit diagram showing a configuration of a fifth embodiment of a power conversion device according to the present invention.

FIG. 6 is a circuit diagram showing a configuration of a sixth embodiment of a power conversion device according to the present invention.

FIG. 7 is a circuit diagram showing a configuration of a seventh embodiment of a power conversion device according to the present invention.

FIG. 8 is a circuit diagram showing a configuration of an eighth embodiment of a power conversion device according to the present invention.

9 is a time chart for explaining the principle and configuration of a reactive power detection signal generator in each of the embodiments shown in FIGS. 7 and 8. FIG.

FIG. 10 is a circuit diagram showing a configuration of a ninth embodiment of a power conversion device according to the present invention.

FIG. 11 is a circuit diagram showing a configuration of a tenth embodiment of a power conversion device according to the present invention.

FIG. 12 is a circuit diagram showing a conventional power conversion device together with a load.

[Explanation of symbols]

1A-1H, 1J, 1K power converter 2,2A, 2B voltage source inverter 3,3A, 3B Inductive impedance 4 Capacitive impedance 5 load 6 transformer 7 Voltage detector 8 Current detector 50 Reactive power control circuit 60 Reactive power detection circuit 62,82 Low pass filter 70 Reactive power detection signal generator 80 Active power detection circuit 90 Active power control circuit

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Claims (7)

[Claims] 1. A voltage-type inverter for converting a DC voltage into a square-wave AC and outputting the AC voltage by controlling a switching element to be turned on and off, and an inductive connected in series between output terminals of the voltage-type inverter. An impedance circuit comprising impedance and capacitive impedance, wherein both ends of the capacitive impedance are connected to a load and a series resonance circuit is formed by the inductive impedance, the capacitive impedance and the load; A power converter that outputs alternating current having a frequency close to the resonance frequency of the series resonance circuit. 2. A transformer having a primary winding connected between output terminals of the voltage source inverter and a transformer in which the inductive impedance and the capacitive impedance are connected in series between terminals of a secondary winding. The power converter according to. 3. A primary winding is connected in series with the inductive impedance between output terminals of the voltage source inverter,
The power converter according to claim 1, further comprising a transformer in which the capacitive impedance is connected in series to a secondary winding. 4. A current detecting means for directly or indirectly detecting an output current of the voltage source inverter, a voltage detecting means for detecting an output voltage of the voltage source inverter, an output current signal of the current detecting means and the Reactive power detecting means for detecting output reactive power of the voltage-type inverter based on an output voltage signal of the voltage detecting means, and reactive power for adjusting the output frequency of the voltage-source inverter so that the detected reactive power is minimized. The power conversion device according to claim 1, further comprising a power control unit. 5. An output of the voltage source inverter based on a current detecting means for directly or indirectly detecting an output current of the voltage source inverter, and an on / off control signal for a switching element forming the voltage source inverter. A signal generating means for generating a reactive power detecting signal whose phase is delayed by 90 degrees with respect to the voltage; and an output current signal of the current detecting means and a reactive power detecting signal of the signal generating means for the voltage source inverter. 4. Reactive power detection means for detecting output reactive power, and reactive power control means for adjusting the output frequency of the voltage source inverter so that the detected reactive power is minimized. The power converter according to item 1. 6. A current detecting means for directly or indirectly detecting an output current of the voltage source inverter, a voltage detecting means for directly or indirectly detecting an output voltage of the voltage source inverter, and a current detecting means of the current detecting means. Active power detection means for detecting the output active power of the voltage source inverter based on the output current signal and the output voltage signal of the voltage detection means; and the voltage so that the detected active power becomes equal to the active power command value. A power converter according to any one of claims 1 to 5, further comprising active power control means for adjusting an output voltage of the inverter. 7. An output of the voltage source inverter based on a current detecting means for directly or indirectly detecting an output current of the voltage source inverter, and an on / off control signal for a switching element forming the voltage source inverter. Signal generating means for generating an active power detection signal synchronized with the voltage; and detecting the output active power of the voltage source inverter based on the output current signal of the current detecting means and the active power detection signal of the signal generating means. 7. An active power detection means, and an active power control means for adjusting the output voltage of the voltage source inverter so that the detected active power becomes equal to an active power command value. The power converter according to the item.