JP2001165965A - Dc-current detecting method and dc-current detecting apparatus for power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC-current detecting method, in which a DC current is detected by using a Rogowski current converter composed of a Rogowski coil and an integrator without being influenced by the pulse shape of the DC current and in which the responsiveness and the accuracy of the detection of the DC current can be improved, and to provide a DC-current detecting apparatus for power conversion device. SOLUTION: A no-current period estimation means 6, which estimates the no-current period for the DC current I, is provided. A switch 4 is closed at its estimated timing by reset pulses which are output from a rest pulse generator 5. The output of the integrator 3 is reset to zero. Thereby, detection errors due to discharging of a capacitor C1 inside the integrator 3 is offset by a reset operation, and the detection accuracy of the DC-current detecting apparatus is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the detection of a direct current in a power converter or the like using a self-extinguishing element.

[0002]

2. Description of the Related Art Conventional types of current detectors include a DCCT using an iron core, a Hall CT using a Hall element and an iron core, and a shunt resistor. In such a case, there is a problem that it is large and expensive. On the other hand, a current detector using a Rogowski coil (hereinafter abbreviated as Rogowski current converter) is used as a detector for measuring a single pulse current of a high-power semiconductor element. As this Rogowski current converter, for example, DEPEOPMENTS IN ROGOWSKI CURRENT on pages 3.308 to 3.312 of EPE '97 (1997).
This is introduced in TRANSDUCERS. Attention is paid to the selection of circuit constants.

The operation of this Rogowski current converter when applied as a DC current detector of a power converter will be described. FIGS. 21 and 22 show a Rogowski current converter and operation waveforms of respective parts thereof, respectively. The DC current I flowing through the DC bus 1 of the power converter and the output voltage Vin of the Rogowski coil 2 (Vin = μ ₀ NAdI / dt) , N is the number of turns, A is the coil cross-sectional area), and the operations of the output voltage Vout of the integrator 3 are compared in correspondence with the pulse width of the DC current. As shown in FIG. 22, the direct current has a pulse shape having a non-current period. If the direct current is a continuation of a narrow pulse current, good responsiveness and accuracy can be ensured. Is continuous, the capacitor C1 of the integrator is partially discharged by the resistor R1 during the current peak period.
Accuracy deteriorates.

In other words, the circuit configuration of the integrator is not a pure integrator, but a resistor R1 is added to a DC to low frequency input signal to lower the gain of the integrator and reduce the error due to the drift of the AMP itself. Has been reduced. By the action of this resistor, if the DC current level at the input of the integrator is zero in a steady state, the output of the integrator becomes zero. Therefore, in the case of the same switching interval, since the period of zero current is long in the narrow pulse, the output of the integrator can be easily attenuated to zero in the zero current period by selecting the time constant of the integrator. Furthermore, if the period during which the current is flowing is short, the output of the integrator during that period will not decrease much. Conversely, in the case of a wide pulse, the integrator output is hardly attenuated to zero during the DC zero period because the current zero period is short. If the time constant of the integrator is shortened and the attenuation is accelerated, the output of the integrator during the current supply period attenuates quickly.

[0005]

When a conventional Rogowski current converter is applied to the detection of a direct current of a power converter, the on-pulse width of the power converter is controlled by a PWM control for performing a switching operation. And sufficient accuracy as a DC current detector could not be obtained. Conversely, if the detection accuracy is to be ensured, the pulse width of the DC current is limited, and the AC output voltage of the power conversion device is reduced, and the output capacity of the power conversion device is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is not affected by the pulse shape of a direct current, and can improve the responsiveness and accuracy of a current detection method and a power converter. An object is to provide a direct current detection device.

[0007]

According to a first aspect of the present invention, there is provided a method for detecting a direct current, comprising means for predicting a non-current period of a direct current. It is to reset.

According to a second aspect of the present invention, there is provided a DC current detecting device for a power converter, wherein a non-current period predicting means for predicting a non-current period of a DC current; Reset means for resetting the output to zero.

The DC current detecting device according to a third aspect of the present invention is configured such that when the current to be detected of the Rogowski current converter rises due to the turn-on operation of the self-turn-off device to which the gate pulse-on signal is applied, The current period prediction means outputs the timing of turning on the gate pulse.

According to a fourth aspect of the present invention, there is provided a DC current detecting device, comprising: a series connection body of a diode and a self-extinguishing element connected between both poles of an input DC power supply; A reactor connected in series with the
And a power converter comprising a step-down chopper by a gate pulse generator for supplying a gate pulse to the self-extinguishing element, comprising a Rogowski current converter for detecting a current flowing through the self-extinguishing element. Detecting the timing of turning on the gate pulse from the gate pulse generator to reset the output of the integrator of the Rogowski current converter to zero.

Further, the DC current detecting device according to claim 5 of the present invention is configured such that when the detected current of the Rogowski current converter rises due to the turn-off operation of the self-extinguishing element to which the gate pulse off signal is applied, The current period prediction means outputs the gate pulse off timing.

A DC current detecting device according to a sixth aspect of the present invention is a DC current detecting device, comprising: a series-connected body of a reactor connected between both poles of an input DC power supply and a self-extinguishing element; A power converter comprising a diode connected in series with an output DC power supply and a gate pulse generator for supplying a gate pulse to the self-extinguishing element, comprising a boost chopper, wherein a Rogowski detects a current flowing through the diode. In the apparatus having a current converter, the timing of turning off the gate pulse from the gate pulse generator is detected, and the output of the integrator of the Rogowski current converter is reset to zero.

A direct current detecting apparatus according to a seventh aspect of the present invention comprises a positive self-extinguishing element connected for each phase between both poles of an input DC power supply, and a diode connected in anti-parallel to the self-extinguishing element. A positive electrode side arm and a negative electrode side self-extinguishing element and a series connection body of a negative electrode side arm composed of a diode connected in anti-parallel thereto, and a gate pulse generator for supplying a gate pulse to the two self-extinguishing elements. A power conversion device comprising a two-level inverter for extracting an AC output from a connection point between both arms, comprising a Rogowski current converter for detecting a current flowing through the positive side arm, wherein Detects the timing of turning off the gate pulse supplied to the negative side self-extinguishing element and resets the output of the integrator of the Rogowski current converter to zero Is shall.

A DC current detecting device according to claim 8 of the present invention is a power conversion device constituting a two-level inverter, comprising a Rogowski current converter for detecting a current flowing through the negative arm. In this device, an output of an integrator of the Rogowski current converter is reset to zero by detecting a timing of turning off a gate pulse supplied from the gate pulse generator to the self-extinguishing element on the positive electrode side.

According to a ninth aspect of the present invention, there is provided a DC current detecting apparatus according to the first to fourth aspects, wherein the input DC power supply having a positive electrode, a neutral electrode, and a negative electrode is connected for each phase between the positive and negative electrodes. A series connection of self-extinguishing elements, first to fourth diodes connected in anti-parallel with the self-extinguishing elements to form first to fourth arms, and a neutral pole of the input DC power supply, respectively Supplying a gate pulse to the fifth and sixth diodes connected between the connection point of the first and second arms and the connection point of the third and fourth arms, and to each of the self-extinguishing elements A power conversion device comprising a three-level inverter for extracting an AC output from a connection point between the second and third arms, the Rogowski current detecting the current flowing through the first arm. Converter The output of the integrator of the Rogowski current converter is reset to zero by detecting the timing of turning off the gate pulse supplied from the gate pulse generator to the third self-extinguishing element. .

A DC current detecting device according to a tenth aspect of the present invention is a power conversion device constituting a three-level inverter, comprising a Rogowski current converter for detecting a current flowing through the fourth arm. Wherein the timing of turning off the gate pulse supplied from the gate pulse generator to the second self-extinguishing element is detected, and the output of the integrator of the Rogowski current converter is reset to zero. .

According to a twelfth aspect of the present invention, there is provided a DC current detecting device, comprising a three-level inverter, comprising a neutral pole of the input DC power source, the fifth and sixth diodes, A Rogowski current converter for detecting a current flowing between the gate pulse generator and the first and fourth self-extinguishing elements. This resets the output of the integrator of the Rogowski current converter to zero.

According to a twelfth aspect of the present invention, there is provided a DC current detecting apparatus according to the present invention, wherein the self-extinguishing element to which the gate pulse-off signal is supplied is turned off by the turn-off operation of the first Rogowski current converter. Falls and the detected current of the second Rogowski current converter rises,
A composite current is obtained by adding the detection current of the second Rogowski current converter and the output current detection value of the power converter that does not change due to the turn-off operation of the self-turn-off device,
The non-current period predicting means for resetting the output of the integrator of the first Rogowski current converter to zero outputs the timing at which the zero level of the combined current is detected.

According to a thirteenth aspect of the present invention, there is provided a DC current detecting device, comprising a two-level inverter, a positive-side Rogowski current converter for detecting a current flowing through the positive-side arm, The negative-side Rogowski current converter for detecting the current flowing through the negative-side arm, and the one provided with an AC current detector for detecting the AC output current, wherein the negative-side Rogowski current converter and the AC current detector A positive-side reset circuit for detecting a timing at which the output sum of the positive-side becomes zero level and generating a reset signal for resetting the output of the integrator of the positive-side Rogowski current converter to zero; and the positive-side Rogowski current converter The output of the integrator of the above-mentioned negative side Rogowski current converter is reset to zero by detecting the timing at which the output sum of the current and the AC current detector becomes zero level. Those comprising a negative electrode side reset circuit for generating a that reset signal.

According to a fourteenth aspect of the present invention, there is provided a DC current detecting device, comprising a three-level inverter, wherein the positive side Rogowski current converter detects a current flowing through the first arm. A negative side Rogowski current converter for detecting a current flowing through the fourth arm, a neutral side detecting a current flowing between a neutral pole of the input DC power supply and the fifth and sixth diodes; Rogowski current converter, and in those having an AC current detector for detecting the AC output current, the output of the negative side Rogowski current converter and the polarity inversion output of the neutral side Rogowski current converter and A positive signal for generating a reset signal for resetting the output of the integrator of the Rogowski current converter on the positive side to zero by detecting the timing when the sum with the output of the AC current detector becomes zero level The reset circuit detects the timing at which the sum of the output of the positive-side Rogowski current converter, the output of the neutral-side Rogowski current converter, and the polarity inversion output of the AC current detector becomes zero level. A negative-side reset circuit for generating a reset signal for resetting the output of the integrator of the negative-side Rogowski current converter to zero; a polarity-inverted output of the positive-side Rogowski current converter and the negative-side Rogowski current converter; And a reset signal for resetting the output of the integrator of the Rogowski current converter on the neutral pole side to zero by detecting the timing when the sum of the output of the AC current detector and the output of the AC current detector becomes zero level. It has a pole-side reset circuit.

According to a twelfth aspect of the present invention, there is provided a DC current detecting apparatus which detects a timing at which an AC output current becomes a zero level and inhibits the output of the reset circuit for a predetermined time from the timing. .

A DC current detecting device according to a sixteenth aspect of the present invention adds the output of the Rogowski current converter according to the seventh aspect to the output of the Rogowski current converter according to the eighth aspect, Alternatively, there is provided an adder for adding the output of the Rogowski current converter on the positive side and the output of the Rogowski current converter on the negative side to detect the AC output current of the two-level inverter.

According to a seventeenth aspect of the present invention, there is provided a DC current detecting apparatus, comprising: an output of the Rogowski current converter according to the ninth aspect; an output of the Rogowski current converter according to the tenth aspect; 15. The output of the Rogowski current converter on the positive electrode side, the output of the Rogowski current converter on the negative electrode side, and the Rogowski current converter on the neutral pole side according to claim 14. And an adder for detecting the AC output current of the three-level inverter by adding the outputs of the three levels.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In FIG.
4 is a switch for short-circuiting the capacitor C1 of the integrator 3;
Is a reset pulse generator for generating an ON command to the switch 4, and 6 is a non-current period predicting means for determining the generation timing of the reset pulse generator 5.

Next, the operation will be described with reference to the operation waveforms of FIG. The no-current period estimating means 6 predicts a no-current period of the DC current, and outputs a reset pulse (FIG. 10C) from the reset pulse generator 5 during the no-current period of the DC current I as shown in the operation waveform of each section. generate. If the DC current I is a wide pulse, the output Vout of the integrator 3 becomes the DC current I
Is attenuated by a time constant determined by the capacitor C1 and the resistor R1 of the integrator 3 during the occurrence period of the integrator 3, and when the current is switched to no current, the level is rapidly attenuated to the level of the opposite polarity, but the switch 4 is closed by the reset pulse. Then, the capacitor C1 of the integrator 3 is rapidly discharged through the switch 4, and the output Vout ((d) in the figure) of the integrator 3 becomes zero. Subsequently, when the DC current I rises, the output Vout of the integrator 3 rises from zero and responds to the DC current I. In the first embodiment, the integrator 3 is reset at each occurrence timing of the non-current period of the DC current I. Therefore, the responsiveness and accuracy are low even when a DC current having a repetitive waveform of a wide pulse is detected. Since a Rogowski current converter that does not require an iron core can be applied, unlike a current detector with a conventional iron core, a small and inexpensive current detector can be obtained.

Embodiment 2 FIG. In the first embodiment, the method of resetting the integrator during the no-current period based on a signal from the no-current period prediction means for predicting the no-current period of the direct current by some method has been described. A description will now be given of a specific non-current period predicting means when the present invention is applied. FIG. 3 shows an example of application to a step-down chopper, where 10a is an input DC power supply having a positive electrode P and a negative electrode N, 11a is a self-extinguishing type semiconductor element such as GTO (hereinafter abbreviated as a self-extinguishing element), 12a Is a diode between the intermediate connection point between the self-extinguishing element 11a and the diode 12a and the negative electrode N of the input DC power supply 10a.
3a and the output DC power supply 14a are connected in series to form a well-known step-down chopper. Reference numerals 2a and 3a denote a Rogowski coil and an integrator, which detect a DC current on the positive electrode P side of the DC input power supply 10a, that is, a DC current Ip flowing through the self-extinguishing element 11a. Reference numeral 6a denotes a gate pulse generator of the step-down chopper, which outputs a gate signal to the self-extinguishing element 11a and, for example, a reset pulse generator 5 comprising a one-shot multivibrator.
a is also output. Reference numeral 4a denotes a switch of the integrator 3a, which is closed by the output of the reset pulse generator 5a.

When a gate pulse ON signal (hereinafter referred to as an ON pulse) is supplied from the gate pulse generator 6a to the self-extinguishing element 11a, the self-extinguishing element 11a conducts and the input DC power supply 10a supplies the self-extinguishing element. 11a, the reactor 13a, and the output DC power supply 14a.
p flows. When the gate pulse is turned off, self-extinguishing element 1
1a becomes non-conductive, and the output DC current Io is
3a, the output DC power supply 14a, and the diode 12a. Accordingly, as shown in the operation waveform of FIG. 4C, the input DC current Ip has a pulse-like waveform according to the switching state of the self-extinguishing element 11a. Strictly speaking,
The turn-on and turn-off operations of the self-extinguishing element 11a have a time delay of several microseconds to several tens of microseconds, so that the input DC current Ip is delayed later than the on / off timing of the gate pulse (FIG. 10A). Rises and falls. The generation timing of the reset pulse is based on the operation time difference between the gate pulse and the DC input current Ip.
The on-pulse generation timing of FIG.
As shown in the operation waveform of (b), a reset pulse (with a pulse width of, for example, about 2 μS) having a width within the operation time difference is applied to the reset switch 4a of the integrator 3a at the rising (on) timing of the gate pulse. ing. By configuring the non-current period predicting means as described above, the responsiveness and accuracy of the DC current detector can be secured.

Embodiment 3 Further, specific non-current period prediction means when applied to another power converter will be described. FIG. 5 shows an example of application to a step-up chopper, where 10b is an output DC power supply having a positive electrode P and a negative electrode N,
1b is a self-extinguishing element, 12b is a diode, and a reactor 13b is provided between an intermediate connection point between the self-extinguishing element 11b and the diode 12b and the negative electrode N of the output DC power supply 10b.
And the input DC power supply 14b are connected in series to form a well-known step-up chopper. 2b and 3b are a Rogowski coil and an integrator, respectively.
, Ie, the DC current Ip flowing through the diode 12b. Reference numeral 6b denotes a gate pulse generator of the step-up chopper, which outputs a gate signal to the self-extinguishing element 11b and also outputs it to the reset pulse generator 5b. Reference numeral 4b denotes a switch of the integrator 3b, which is closed by an output of the reset pulse generator 5b.

When an on-pulse is applied from gate pulse generator 6b to self-extinguishing element 11b, self-extinguishing element 11
b conducts and the input DC power supply 14b
b, DC input current Io flows through the path of self-extinguishing element 11b. When the gate pulse is turned off, the self-extinguishing element 11b becomes non-conductive, and the input DC current Io is
It flows through the path of the output DC power supply 10b. Accordingly, the output DC current Ip has a pulse-like waveform according to the switching state of the self-extinguishing element 11b as shown in the operation waveform of FIG. 6C. Strictly speaking, the turn-on and turn-off operations of the self-extinguishing element 11b have a time delay of several microseconds to several tens of microseconds, so that the gate pulse ((a) in FIG.
The output DC current Ip rises and falls later than the OFF timing. The generation timing of the reset pulse utilizes the operation time difference between the gate pulse and the current Ip. That is, here, the generation timing of the gate pulse off signal of the gate pulse generator 6b is adopted as the no-current period prediction means. As shown in the operation waveform of FIG. 6B, a reset pulse having a width within the operation time difference is given to the reset switch 4b of the integrator 3b at the timing of the fall (off) of the gate pulse. By configuring the non-current period predicting means as described above, the responsiveness and accuracy of the DC current detector can be secured.

Embodiment 4 Further, a specific non-current period prediction unit when applied to another power converter will be described. FIG. 7 shows an example of application to a two-level inverter, where 10c is an input DC power supply having a positive electrode P and a negative electrode N, 11P and 11N are self-extinguishing elements connected in series and Connected between the positive electrode P and the negative electrode N, 12P and 12N are diodes which are connected in anti-parallel to the self-extinguishing elements 11P and 11N, respectively, from the intermediate connection point between the self-extinguishing elements 11P and 11N. One phase of a well-known two-level inverter is obtained so as to obtain an AC output terminal AC (an AC power supply or an AC motor generally including an inductance element is connected to the AC terminal side, but is omitted in the drawing). Minutes are configured.
Reference numerals 2P and 3P denote a Rogowski coil and an integrator, respectively, which detect a DC current Ip flowing through a positive arm formed by a self-extinguishing element 11P and a diode 12P. Reference numerals 2N and 3N denote a Rogowski coil and an integrator, respectively, which detect a DC current In flowing through a negative arm formed by a self-extinguishing element 11N and a diode 12N. Reference numeral 6c denotes a gate pulse generator of the two-level inverter, which outputs a gate signal to the self-extinguishing elements 11P and 11N as well as to the reset pulse generators 5P and 5N. 4P and 4N are switches of the integrators 3P and 3N, respectively, and perform a closing operation by the outputs of the reset pulse generators 5P and 5N.

In the operation waveform shown in FIG. 8, when the output current Io of the power converter flows with the polarity shown in FIG. 7 (hereinafter, defined as positive polarity) ([I] in FIG. 8) In the state where an ON pulse is applied from gate pulse generator 6c to self-extinguishing element 11P, input DC power supply 10
An output current Io of the power converter flows from the positive pole P of the power supply c through the self-extinguishing element 11P. Next, when a gate-pulse-off signal (hereinafter, referred to as an off-pulse) is applied to the self-arc-suppressing element 11P, the self-arc-suppressing element 11P becomes non-conductive, and the power is converted from the negative electrode N of the input DC power supply 10c through the diode 12N. The output current Io of the device flows. Self-extinguishing element 11
An on-pulse is given to the self-turn-off element 11N after the DC short-circuit prevention period Td from the point of occurrence of the off-pulse to P, but the output current Io of the power converter continues to flow through the diode 12N, and When the self-extinguishing element 11P is turned on by the ON pulse, the current of the diode 12N commutates to the self-extinguishing element 11P.

Next, when the polarity of the output current Io of the power converter is opposite to that shown in FIG. 8 ([II] in FIG. 8), the output current Io is reduced to the diode 12P even if an ON pulse is given to the self-extinguishing element 11P. Through the positive pole P of the input DC power supply 10c.
To the next self-extinguishing element 11N,
When the self-extinguishing element 11N conducts, the current of the diode 12P commutates to the self-extinguishing element 11N. Thereafter, due to the off-pulse of the self-extinguishing element 11N, the current of the self-extinguishing element 11N is diverted to the diode 12P.
It keeps flowing through the diode 12P until an ON pulse is given to 1N. Thus, the P-side and N-side DC currents Ip
As shown in FIGS. 8 (e), (f), (i) and (j), In has a pulse-like waveform in accordance with the switching state of the self-extinguishing elements 11P and 11N. Due to the switching operation delay of 11N, the rising and falling operations of the DC currents Ip and In also have a time delay from the gate pulse generation time.

The generation timing of the reset pulse is shown in FIG.
(C) As shown in the operation waveforms of (d), for the switch 4P of the integrator 3P that detects the DC current Ip on the P side, the falling timing of the ON pulse to the self-extinguishing element 11N (that is, self-extinguishing) The reset pulse is generated by the reset pulse generator 5P at the timing of the off pulse to the element 11N), the circuit is closed, and the switch 4N of the integrator 3N that detects the N-side DC current In is connected to the self-extinguishing element 11P.
A reset pulse is generated by the reset pulse generator 5N at the falling timing of the ON pulse to P (that is, the timing of the OFF pulse to the self-extinguishing element 11P) to close the circuit. By configuring the non-current period prediction means in this manner, the reset operation of the integrator can be reliably performed during the non-current period of the DC current regardless of the polarity of the AC output current Io, and the responsiveness and accuracy of the DC current detector can be improved. Can be secured.

Embodiment 5 Further, a specific non-current period prediction unit when applied to another power converter will be described. FIG. 9 shows an example of application to a three-level inverter, where 10p and 10n are connected in series in an input DC power supply having a positive pole P, a neutral pole C and a negative pole N, 11P1, 11P.
P2, 11N2, and 11N1 are first to fourth self-extinguishing elements which are connected in series and connected between the positive pole P of the input DC power supply 10p and the negative pole N of the input DC power supply 10n. 12N2 and 12N1 are first to fourth diodes which are connected in anti-parallel to the self-turn-off devices 11P1, 11P2, 11N2 and 11N1, respectively. Between the neutral pole C, which is an intermediate connection point between the DC power supply 10p and the input DC power supply 10n, and the intermediate connection point between the self-extinguishing elements 11P1 and 11P2, and between the neutral pole C and the self-extinguishing element 11N2. 11N1
The self-extinguishing element 1
AC output terminal AC from the intermediate connection point between 1P2 and 11N2
(An AC power supply or an AC motor including an inductance element is generally connected to the AC terminal side, but is omitted from the drawing.) One phase of a well-known three-level inverter is configured so as to be obtained. You.

Reference numerals 2P and 3P denote a Rogowski coil and an integrator, respectively, which are a self-extinguishing element 11P1 and a diode 1P.
The DC current Ip flowing through the first arm composed of 2P1 is detected. 2N and 3N are a Rogowski coil and an integrator, respectively.
The DC current In flowing through the fourth arm composed of N1 is detected. Reference numerals 2C and 3C denote a Rogowski coil and an integrator, respectively, which detect a DC current Ic flowing between the neutral pole C, which is an intermediate connection point between the input DC power supplies 10p and 10n, and the diodes 15P and 15N. 6d
Is a gate pulse generator of the above three-level inverter, and includes self-extinguishing elements 11P1, 11P2, 11N2, 11
It is output to N1 as a gate signal and is also output to reset pulse generators 5P, 5N, and 5C. 4P, 4
N, 4C are switches of the integrators 3P, 3N, 3C, respectively, and the reset pulse generators 5P, 5N,
The circuit is closed by the output of 5C.

In the operation waveform shown in FIG. 10, when the output current Io of the power converter flows in the polarity shown in FIG. 9 (hereinafter, defined as positive polarity) ([I] in FIG. 10).
The self-extinguishing element 11P from the gate pulse generator 6d.
2 and 11N2, the output current Io of the power converter flows from neutral side C of input DC power supplies 10p and 10n through diode 15P and self-extinguishing element 11P2. Next, the self-extinguishing element 11
When an off-pulse is applied to N2, the self-extinguishing element 11N2 becomes non-conductive, but the output current Io continues to flow through the diode 15P and the self-extinguishing element 11P2,
DC short circuit prevention period T from the time of off pulse generation to 1N2
When an ON pulse is given to the self-extinguishing element 11P1 after d,
The output current Io of the power converter is commutated from the diode 15P to the self-extinguishing element 11P1, and the output current Io flows from the positive pole P of the input DC power supply 10p through the self-extinguishing elements 11P1 and 11P2.

Next, when an off-pulse is applied to the self-turn-off device 11P1, the self-turn-off device 11P1 becomes non-conductive, and the output current Io is again commutated to the diode 15P and flows. Even if the on-pulse is again applied to the self-extinguishing element 11N2 after Td from the time of generation of the off-pulse to the self-extinguishing element 11P1, the flow path of the output current Io does not change. Next, when an off-pulse is given to the self-extinguishing element 11P2,
Becomes non-conductive, the output current Io flows from the negative electrode N of the input DC power supply 10n through the diodes 12N1 and 12N2, and even if an on-pulse is given to the self-extinguishing element 11N1 after Td, the flow path of the output current Io Does not change, and when an off-pulse is applied to the self-extinguishing element 11N1 and an on-pulse is applied again to the self-extinguishing element 11P2 after Td, the output current Io changes from the neutral pole C to the diode 15P and the self-extinguishing element 11P2. Flow through.

Next, when the polarity of the output current Io of the power converter is opposite to that shown in FIG. 10 ([II] in FIG. 10), the output is maintained when the on-pulse is given to the self-extinguishing elements 11P2 and 11N2. Current Io flows to neutral pole C through self-extinguishing element 11N2 and diode 15N. Next, when an off-pulse is applied to self-turn-off element 11N2, self-turn-off element 11N2 becomes non-conductive, and output current Io flows to positive pole P of input DC power supply 10p through diodes 12P2 and 12P1. Even if an on-pulse is applied to the self-extinguishing element 11P1 after Td, the flow path of the output current Io does not change.
When the ON pulse is again applied to the self-extinguishing element 11N2 after d, the output current Io flows to the neutral pole C through the self-extinguishing element 11N2 and the diode 15N. Next, even if an off-pulse is applied to self-turn-off element 11P2, the flow path of output current Io does not change, and after Td, self-turn-off element 11N1
When an on-pulse is applied, the diode 15N commutates to the self-extinguishing element 11N1, and the output current Io becomes
It flows to the negative electrode N of the input DC power supply 10n through 1N2 and 11N1.

Next, when an off-pulse is applied to the self-turn-off element 11N1, the self-turn-off element 11N1 becomes non-conductive, and the output current Io is again increased by the self-turn-off element 11N2 and the diode 15N.
Through the neutral pole C side. Even if an on-pulse is applied to the self-extinguishing element 11P2 after Td, the flow path of the output current Io does not change. As described above, the DC currents Ip, Ic, and In on the P, C, and N sides are illustrated (FIG. 10H).
As shown in (i) (j) (n) (o) (p)), a pulse-like waveform is formed according to the switching state of the self-extinguishing elements 11P1, 11P2, 11N2, 11N1, and the self-extinguishing elements 11P1, Due to the switching operation delay of 11P2, 11N2, and 11N1, the rising and falling operations of DC currents Ip, Ic, and In also have a time delay from the gate pulse generation time.

The generation timing of the reset pulse is shown in FIG.
As shown in the operation waveforms of (e), (f), and (g), for the switch 4P of the integrator 3P that detects the P-side DC current Ip, the falling timing of the ON pulse to the self-extinguishing element 11N2 (ie, The reset pulse is generated by the reset pulse generator 5P at the timing of the off-pulse of the self-extinguishing element 11N2), the circuit is closed, and the switch 4N of the integrator 3N for detecting the DC current In on the N side is self-extinguishing element 11P2. The reset pulse is generated by the reset pulse generator 5N at the falling timing of the ON pulse (ie, the timing of the OFF pulse of the self-turn-off device 11P2), the switch is closed, and the switch 4C of the integrator 3C detects the DC current Ic on the C side. Self-extinguishing element 11P
1 (that is, the timing of the off-pulse of the self-turn-off element 11P1) and the reset pulse generated by the reset pulse generator 5CP and the falling timing of the on-pulse to the self-turn-off element 11N1 (that is, the self-turn-off element) At the timing of the off pulse of 11N1, a reset pulse is generated by the output of the OR circuit 5CO of the reset pulse generated by the reset pulse generator 5CN and the circuit is closed. By configuring the no-current period prediction means in this way, the AC output current Io
Irrespective of the polarity of the DC current, the reset operation of the integrator can be reliably performed during the non-current period of the DC current, and the responsiveness and accuracy of the DC current detector can be secured.

Embodiment 6 FIG. Embodiment 2 above
In No. 5, a non-current period predicting means based on switching timing from a gate pulse generator in various types of power conversion devices is described as a non-current period predicting means. Specific non-current period predicting means based on other principles will be described. .
FIG. 11 shows an example of application to a two-level inverter.
The main circuit is the same as that of FIG. 7 except that an output current detector 16 which is a conventional AC current detector is added to the output terminal AC side. 17P is an adder for adding the output VoutN of the integrator 3N for detecting the N side DC current In and the output VoutO of the output current detector 16, and 18P is a 0 level for detecting the 0 level of the output of the adder 17P. A detector whose output is a reset pulse generator 5P
Given to. Reference numeral 19 denotes a polarity inverter which inverts the polarity of the output VoutO of the output current detector 16. 17
N is the output V of the integrator 3P for detecting the DC current Ip on the P side.
An adder 18N for adding outP to the output of the polarity inverter 19 is a 0 level detector for detecting a 0 level of the output of the adder 17N, and the output is supplied to a reset pulse generator 5N.

Next, the operation will be described with reference to FIG. Although the polarity of the output current Io is assumed to be constant at the illustrated positive polarity, the same operation is performed in the case of the negative polarity. The operation of the main circuit is omitted to avoid duplication of the description. In the two-level inverter, as will be understood from the detailed description of the operation of the main circuit in FIGS. Io = Ip-In (1) From the above equation (1), the direct currents Ip and In can be expanded as follows. Ip = Io + In (2) In = Ip−Io (3)

The non-current period predicting means according to the sixth embodiment is based on the above equations (2) and (3).
This is to estimate the non-current period of p and In. When an off-pulse is applied from the gate pulse generator 6C to the self-extinguishing element 11P, the self-extinguishing element 11P becomes non-conductive,
When the DC current Ip on the P side becomes 0 and the AC output current I
o flows through the diode 12N. As a result, Io
By setting = −In, if Io and In are known, the timing at which Ip = 0 can be predicted from the above equation (2).
When the polarity of the AC output current Io is positive, the self-arc-extinguishing element 1N is gated off and the self-arc-extinguishing element 1N is turned on after Td.
When the gate of 1P is turned on, the AC output current Io commutates from the diode 12N to the self-extinguishing element 11P and flows. As a result, when Io = Ip, if Io and Ip are known, the timing at which In = 0 can be predicted from the above equation (3).

The adder 17P uses the calculation of the above equation (2) for the prediction of Ip and Vou, which is the detected value of Io and In.
This is performed by using tO and VoutN.
7N performs the operation of the above equation (3) for the prediction of In using the detected values VoutO and VoutP of Io and Ip. As a result, the adders 17P and 17P
As the output of N, the same waveform as the actual DC currents Ip and In is obtained (FIG. 12 (h) (i)). 0 level detector 1
8P and 18N detect the 0 level of the outputs of the adders 17P and 17N and output L (FIG. 12 (j)).
(K)). The reset pulse generators 5P and 5N generate reset pulses immediately after the falling points of the outputs of the 0-level detectors 18P and 18N (that is, the points at which the currents of Ip and In change to 0) (FIG. 12 (l)).
(M)). By configuring the non-current period predicting means in this manner, the reset operation of the integrator can be reliably performed at the beginning of the non-current period of the DC current, and the responsiveness and accuracy of the DC current detector can be secured.

It is also conceivable to determine a no-current period from the output of the own integrator itself and reset the own integrator. However, a desired result cannot be obtained for the following reasons. That is, in the method of resetting at the timing of the falling edge of the output of the integrator, the current does not become zero when the ripple fluctuation of the current is considered. There is a disadvantage that it increases. In the method of detecting the zero level of the output of the integrator, the current zero point may not be accurately detected due to the accumulated error during the integration of the conducting current having a complicated waveform. On the other hand, in the method according to the sixth embodiment, the AC output current Io to be added does not change when the DC current changes abruptly. Prediction of the no-current period for resetting 3P is performed by detecting the timing at which the output rises from zero for the integrator 3N on the opposite side, so that the error of the integrator is small and accurate prediction is possible. That is,

Embodiment 7 FIG. In the sixth embodiment described above, the non-current period predicting means in the two-level inverter is configured to predict by calculation from each detection value of the AC output current and the DC current on the pole side of the DC power supply pair. However, a specific non-current period predicting means that can cope with a case where an instantaneous fluctuation occurs in the AC output current Io will be described.

The following are conceivable factors for the instantaneous variation of the AC output current. (1) Ripple component of AC output current Occurs depending on the switching frequency of the inverter and converter. Especially near the zero point of the instantaneous value of the AC output current, the influence of the ripple always occurs. If the switching frequency of the GCT is 1 kHz, the ripple frequency is generally 1 k
Hz. If applied to an IGBT, it will be about 10 kHz. (2) Sudden change of AC power supply voltage, sudden change of load (3) Hunting frequency of current control system such as current hunting due to malfunction of output current control
Hz.

FIG. 13 shows an example of application to a two-level inverter. The following circuit is added to the circuit configuration of FIG. That is, reference numeral 180 denotes a 0 level detector, which is the output VoutO of the output current detector 16 on the output terminal AC side.
Detect level. 20 is an off delay circuit,
The output of the 0-level detector 180 is output as a signal obtained by extending the 0-period of the current by a predetermined time by an off-delay operation. Reference numerals 21P and 21N denote AND circuits, which perform an AND operation between the output of the off-delay circuit 20 and the reset pulse generators 5P and 5N, respectively, and the outputs are supplied to switches 4P and 4N, respectively.

Next, the operation will be described with reference to FIG. The figure shows a case where the AC output current Io suddenly changes from the positive polarity to the negative polarity and returns once during each operation mode period of the two-level inverter. DC current Ip, I
The output waveforms of the adders 17P and 17N for predicting n (FIG. 14)
(H) (i)) is similar to the actual current, and the frequency of passing the current zero point increases. Therefore, the 0 level detector 18
The frequency of the outputs of the P and 18N drop from the H level to the L level increases, and the number of reset pulses of the outputs of the reset pulse generators 5P and 5N increases (FIG. 14 (n)).
(O)). If the polarity inversion time of the AC output current Io is short, the current detection accuracy deteriorates because the zero period of the forcibly generated current increases, depending on the reset pulse width. In order to eliminate such a problem, the AC output current Io
From the output VoutO of the output current detector 16 to the 0 level detector 180 and the AC output current I
A signal (FIG. 14 (m)) obtained by extending the zero period of o is obtained, and an AND operation with the outputs of the reset pulse generators 5P and 5N is performed to generate a reset pulse signal (FIG. 14 (p)) to the switches 4P and 4N. q)) to prohibit an extra reset operation.

The off-delay time of the off-delay circuit 20 is set according to the zero-point setting level and the time rate of change of the current. To prevent the generation of two consecutive reset pulses at the zero detection point, at least the The pulse width needs to be twice or more the pulse width, and an off-delay time of about 5 to 10 μS is set.

By configuring the non-current period estimating means in this way, even when the polarity of the AC output current is suddenly changed, an unnecessary reset operation can be suppressed and a necessary reset operation can be reliably performed. Responsiveness and accuracy can be secured.

Embodiment 8 FIG. Note that the sixth embodiment,
In FIG. 7, the case where the no-current period prediction means using the AC output current detector is applied to a two-level inverter is described. However, the case where it is applied to a three-level inverter will be described. FIG. 15 shows an example of application to a three-level inverter, which has the same main circuit as that of FIG. 9 except that a conventional output current detector 16 is added to the output terminal AC side. 17P1 is an integrator 3 for detecting the DC current In on the N side.
A signal obtained through a polarity inverter 19C of the output VoutC of the integrator 3C for detecting the output VoutN of N and the DC current Ic on the C side, and the output Vout of the output current detector 16
O and an adder 17C1 are a DC current Ip on the P side.
Polarity inverter 1 of output VoutP of integrator 3P for detecting
9P, the VoutO and the Vo
utN and 17N1 are the above-mentioned VoutO.
And the signal obtained through the polarity inverter 19O of FIG.
adders for adding tP and VoutC, 180, 18
P, 18C, and 18N are 0 level detectors, each of which is the VoutO and the adders 17P1, 17C1, and 17P, respectively.
N1 is provided as an input signal. Reference numeral 20 denotes an off delay circuit, which is connected to the output of the 0 level detector 180. Reference numerals 5P, 5C, and 5N denote reset pulse generators, which are the 0-level detectors 18P, 18C, and 1P, respectively.
Connected to 8N output. 21P, 21C, 21N are A
An ND circuit, which performs an AND operation on the output of the off-delay circuit 20 and the output of each of the reset pulse generators 5P, 5C, and 5N, and outputs the outputs to the switches 4P, 4C, and 4N, respectively.

Next, the operation will be described with reference to FIG. It is assumed that the polarity of the AC output current Io is positive in the figure and a sudden change to negative polarity occurs momentarily during a constant current. The same operation is performed when the polarity of the AC output current Io is negative. The operation of the main circuit is omitted to avoid duplication of the description. In the three-level inverter, as will be understood from the detailed description of the operation of the main circuit in FIGS.

Io = Ip−In + Ic (4) From the above equation (4), the direct currents Ip, Ic and In can be expanded as follows. Ip = Io + In-Ic (5) Ic = Io-Ip + In (6) In = -Io + Ip + Ic (7)

The non-current period predicting means in the eighth embodiment is based on the above equations (5), (6) and (7).
The current-free period of p, Ic and In is predicted. From the gate pulse generator 6d to the self-extinguishing element 11P1
And 11P2 are supplied with an on-pulse to change the state of the P-side DC current Ip = AC output current Io from
When an off pulse is applied to P1, the self-extinguishing element 11P
1 becomes non-conductive, the P-side DC current Ip becomes 0, and the AC output current Io flows through the diode 15P and the self-extinguishing element 11P2, and Io = Ic. Subsequently, when an on-pulse is applied to the self-extinguishing element 11N2 and then an off-pulse is applied to the self-extinguishing element 11P2, the self-extinguishing element 11P2 becomes non-conductive, and the AC output current Io flows through the diodes 12N1 and 12N2, Io = -In
become.

As described above, the AC output current Io flows to one of the P side, C side, and N side of the DC power supply according to the switching state of the self-extinguishing elements 11P1, 11P2, 11N1, and 11N2. The adders 17P1, 17C1, and 17N1 output current detection signals VoutO, VoutP, and V
Using outC and VoutN, Ip, Ic, and In are calculated based on the above equations (5), (6), and (7), respectively.
(FIG. 16 (l) (m))
(N)). Zero level detectors 18P, 18C and 18N
Are omitted in FIG. 16, but the adders 17P1, 1P
Detects the 0 level of the outputs of 7C1 and 17N1, and outputs L. The reset pulse generators 5P, 5C and 5N generate reset pulses immediately after the falling points of the outputs of the 0-level detectors 18P, 18C and 18N (that is, when the currents of Ip, Ic and In change to 0). (FIG. 16 (q) (r) (s)).

Next, a case where the AC output current Io suddenly changes to the negative polarity for a moment will be described. In FIG. 16, when the AC output current Io fluctuates as shown in FIG. 16 (e) during the period in which the ON pulses are applied to the self-turn-off devices 11P2 and 11N2, the zero level detector 1 of the AC output current Io
The output of 80 drops twice to L level (FIG. 16)
(O)), a reset signal is generated at the same timing as the output of the reset pulse generator 5C (FIG. 16 (r)).
However, the output of the OFF delay circuit 20 (FIG. 16 (p)) prohibits the generation of the reset pulse at the output of the AND circuit 21C (FIG. 16 (u)).

By configuring the non-current period predicting means in this way, the reset operation of the integrator can be reliably performed at the beginning of the non-current period of the DC current, and the extra operation can be performed even when the polarity of the AC output current suddenly changes. Reset operation can be suppressed, and the responsiveness and accuracy of the DC current detector can be secured.

Embodiment 9 In the fourth embodiment, the case where the non-current period predicting means using the off timing of the self-turn-off device is applied to the two-level inverter has been described. A method for detecting the AC output current of the two-level inverter will now be described. FIG. 17 is obtained by adding a circuit for detecting the AC output current Io to FIG.
Reference numeral 2 denotes an adder for adding a detection signal VoutP of the P-side DC current Ip and a signal obtained through the polarity inverter 19N of the detection signal VoutN of the N-side DC current In, and outputs an AC output current detection signal Io2. The relational expression of each part in the two-level inverter is obtained by the above equation (1), and the detection signal Io2 of the AC output current is calculated based on this relational expression. That is, Io2 = VoutP−V
outN.

FIG. 18 shows this operation waveform. In the thus obtained AC output current detection signal Io2 (FIG. 18 (j)), an offset immediately before the reset operation of the integrators 3P and 3N appears. . In this operation waveform diagram, the offset is exaggerated, but in practice, the offset can be reduced to 1% or less by appropriate selection of the integrator and the repetitive reset means according to the present invention. However, the detection accuracy of the AC output current of the inverter is sufficiently acceptable. By configuring the detection circuit for the AC output current in this way, the responsiveness can be improved even when the AC output has a low frequency.
Since the accuracy can be ensured and the conventional AC current detector using the iron core can be omitted, the power converter can be inexpensive.

Embodiment 10 FIG. The ninth embodiment
In the above, the case where the method of detecting the AC output current using the DC current detector by the no-current period prediction means using the timing of turning off the self-extinguishing element is applied to the two-level inverter, but the output current of the three-level inverter is described. The method for detecting the error will be described. FIG. 19 is obtained by adding a circuit for detecting the AC output current Io to FIG.
17O3 is the detection signal VoutP of the P-side DC current Ip and N
Polarity inverter 19 of detection signal VoutN of side DC current In
An adder that adds a signal obtained through N and a detection signal VoutC of the C-side DC current Ic outputs an AC output current detection signal Io3. The relational expression of each part in the three-level inverter is obtained by the above equation (4), and the detection signal Io3 of the AC output current is calculated based on this relational expression. That is, Io3 = VoutP-Vout
N + VoutC.

FIG. 20 shows this operation waveform. In the output current detection signal Io3 ((o) in FIG. 20) obtained in this manner, an offset just before the reset operation of the integrators 3P and 3N appears. In this operation waveform diagram, the offset is exaggerated, but in practice, the offset can be reduced to 1% or less by appropriate selection of the integrator and the repetitive reset means according to the present invention. However, the detection accuracy of the AC output current of the inverter is sufficiently acceptable. By configuring the detection circuit for the AC output current in this way, the responsiveness can be improved even when the AC output has a low frequency.
Since the accuracy can be ensured and the conventional AC current detector using the iron core can be omitted, the power converter can be inexpensive.

It should be noted that in Embodiments 2 to 10 above,
Although all cases have been described in which the present invention is applied to a power converter using a self-extinguishing element, if it is possible to predict the non-current period of DC current by any method, the present invention
As described in the first embodiment, the present invention can be applied to the detection of a direct current in a device that is not particularly related to the power converter, and has the same effect.

In the second embodiment, the case where the present invention is applied to the detection of a predetermined direct current of the step-down chopper as the power converter has been described. However, the present invention is not limited to this. In the case where the detected current of the Rogowski current converter rises due to the turn-on operation of the self-turn-off device, the output of the integrator is reset to zero at the timing of the gate pulse on, The present invention can be applied in the same manner and has the same effect.

In the third to fifth embodiments, the case where the present invention is applied to the detection of a predetermined direct current of a boost chopper, a two-level inverter, and a three-level inverter has been described. However, the present invention is not limited to this. In the case where there is an operation relationship in which the detected current of the Rogowski current converter rises due to the turn-off operation of the self-extinguishing element to which the pulse-off signal is given, the output of the integrator is set to zero at the timing of the gate pulse-off. By resetting to, the present invention can be similarly applied, and the same effect can be obtained.

Further, in Embodiments 6 to 8 described above, 2
The case where the present invention is applied to the detection of a predetermined direct current of a level inverter and a three-level inverter has been described. However, the present invention is not limited to this. 1
In the case where there is an operation relationship in which the detected current of the Rogowski current converter falls and the detected current of the second Rogowski current converter rises, the above-mentioned timing is detected at the timing when the zero level of the combined current is detected. By resetting the output of the integrator of the first Rogowski current converter to zero, the present invention can be applied in the same way, with the same effect.

[0067]

As described above, the DC current detecting method according to the first aspect of the present invention includes the means for predicting the non-current period of the DC current, and makes the output of the integrator zero during the predicted non-current period. , The error in the integrator, which occurred during the period of the direct current pulse width, is settled to zero by the reset operation, the phenomenon that the error is accumulated is prevented, and the detection of the DC current with high accuracy Becomes possible.

According to a second aspect of the present invention, there is provided a DC current detecting device for a power converter, comprising: a non-current period predicting means for predicting a non-current period of a DC current; Since the reset means for resetting the output of the power converter to zero is provided, the DC current of each part of the power converter can be detected with high accuracy.

Further, the DC current detecting device according to the third aspect of the present invention is configured such that when the detected current of the Rogowski current converter rises due to the turn-on operation of the self-extinguishing element to which the gate pulse ON signal is applied, Since the current period estimating means outputs the timing of turning on the gate pulse, it is possible to detect the DC current with good responsiveness and high accuracy by using the signal of turning on the gate pulse to the self-extinguishing element.

A DC current detecting device according to a fourth aspect of the present invention is a DC current detecting device, comprising: a series connection of a self-extinguishing element and a diode connected between both poles of an input DC power supply; A reactor connected in series with the
And a power converter comprising a step-down chopper by a gate pulse generator for supplying a gate pulse to the self-extinguishing element, comprising a Rogowski current converter for detecting a current flowing through the self-extinguishing element. Since the output of the integrator of the Rogowski current converter is reset to zero by detecting the timing of turning on the gate pulse from the gate pulse generator, the signal of turning on the gate pulse to the self-extinguishing element is used. In addition, the direct current flowing through the self-extinguishing element in the step-down chopper can be detected with excellent responsiveness and accuracy.

Further, the DC current detecting device according to claim 5 of the present invention provides a DC current detecting device in which the detected current of the Rogowski current converter rises due to the turn-off operation of the self-extinguishing element to which the gate pulse-off signal is applied. Since the current period prediction means outputs the gate pulse off timing, it is possible to detect a DC current with good responsiveness and high accuracy by using the gate pulse off signal to the self-extinguishing element.

A direct current detecting device according to a sixth aspect of the present invention is a direct current detecting device, comprising: a series connection of a reactor connected between both poles of an input DC power supply and a self-extinguishing element; A power converter comprising a diode connected in series with an output DC power supply and a gate pulse generator for supplying a gate pulse to the self-extinguishing element, comprising a boost chopper, wherein a Rogowski detects a current flowing through the diode. In a device provided with a current converter, the timing of the gate pulse off from the gate pulse generator is detected and the output of the integrator of the Rogowski current converter is reset to zero. Utilizing the signal, the direct current flowing through the diode in the boost chopper can be detected with excellent responsiveness and accuracy.

A direct current detecting device according to a seventh aspect of the present invention comprises a positive self-extinguishing element connected between the two poles of an input DC power supply for each phase and a diode connected in anti-parallel to the self-extinguishing element. A positive electrode side arm and a negative electrode side self-extinguishing element and a series connection body of a negative electrode side arm composed of a diode connected in anti-parallel thereto, and a gate pulse generator for supplying a gate pulse to the two self-extinguishing elements. A power conversion device comprising a two-level inverter for extracting an AC output from a connection point between both arms, comprising a Rogowski current converter for detecting a current flowing through the positive side arm, wherein Detects the timing of turning off the gate pulse supplied to the negative side self-extinguishing element and resets the output of the integrator of the Rogowski current converter to zero Runode, by using the signal of the gate pulse off into self-turn-off devices, the DC current flowing to the positive electrode-side arm of the two-level inverter, it is possible to responsiveness, accuracy of better detection.

According to an eighth aspect of the present invention, there is provided a DC current detecting apparatus, comprising a two-level inverter, comprising a Rogowski current converter for detecting a current flowing through the negative arm. In this device, the output of the integrator of the Rogowski current converter is reset to zero by detecting the timing of turning off the gate pulse supplied from the gate pulse generator to the positive electrode self-extinguishing element. Utilizing the signal of the gate pulse off to the element, it is possible to detect the DC current flowing in the negative arm of the two-level inverter with excellent responsiveness and accuracy.

The DC current detector according to claim 9 of the present invention is characterized in that the input DC power supply having a positive electrode, a neutral electrode, and a negative electrode is connected between the positive and negative electrodes for each phase. A series connection of self-extinguishing elements, first to fourth diodes connected in anti-parallel with the self-extinguishing elements to form first to fourth arms, and a neutral pole of the input DC power supply, respectively A gate pulse is supplied to the fifth and sixth diodes connected between the connection point of the first and second arms and the connection point of the third and fourth arms, and to each of the self-extinguishing elements. A power conversion device comprising a three-level inverter for extracting an AC output from a connection point between the second and third arms, the power conversion device including a gate pulse generator that performs a switching operation, and detecting a current flowing through the first arm. Converter In this case, the output of the integrator of the Rogowski current converter is reset to zero by detecting the timing of turning off the gate pulse supplied from the gate pulse generator to the third self-extinguishing element. Utilizing the gate pulse-off signal to the arc-extinguishing element, it is possible to detect the DC current flowing through the first arm of the three-level inverter with excellent responsiveness and accuracy.

A DC current detecting apparatus according to a tenth aspect of the present invention is a power conversion apparatus constituting a three-level inverter, comprising a Rogowski current converter for detecting a current flowing through the fourth arm. In this case, the output of the integrator of the Rogowski current converter is reset to zero by detecting the timing of turning off the gate pulse supplied from the gate pulse generator to the second self-extinguishing element. Utilizing the gate pulse off signal to the arc-extinguishing element, it is possible to detect the DC current flowing through the fourth arm of the three-level inverter with excellent responsiveness and accuracy.

According to a twelfth aspect of the present invention, there is provided a DC current detecting device, comprising a three-level inverter, comprising a neutral pole of the input DC power source, the fifth and sixth diodes, A Rogowski current converter for detecting a current flowing between the first and fourth self-turn-off devices from the gate pulse generator. Since the output of the integrator of the Rogowski current converter is reset to zero, the neutral pulse of the input DC power supply of the three-level inverter and the fifth and sixth power supplies are utilized by utilizing the gate pulse off signal to the self-extinguishing element. , A highly accurate detection of the direct current flowing between the diode and the diode.

According to a twelfth aspect of the present invention, there is provided a DC current detecting apparatus, wherein the self-turn-off device to which the gate pulse-off signal is supplied is turned off by the turn-off operation of the first Rogowski current converter. Falls and the detected current of the second Rogowski current converter rises,
A composite current is obtained by adding the detection current of the second Rogowski current converter and the output current detection value of the power converter that does not change due to the turn-off operation of the self-turn-off device,
The non-current period predicting means for resetting the output of the integrator of the first Rogowski current converter to zero outputs the timing at which the zero level of the combined current is detected. The first Rogowski current converter utilizing the rising phenomenon of the detection output enables current detection with excellent responsiveness and accuracy.

According to a thirteenth aspect of the present invention, there is provided a DC current detecting device, comprising a two-level inverter, a positive-side Rogowski current converter for detecting a current flowing through the positive-side arm, The negative-side Rogowski current converter for detecting the current flowing through the negative-side arm, and the one provided with an AC current detector for detecting the AC output current, wherein the negative-side Rogowski current converter and the AC current detector A positive-side reset circuit for detecting a timing at which the output sum of the positive-side becomes zero level and generating a reset signal for resetting the output of the integrator of the positive-side Rogowski current converter to zero; and the positive-side Rogowski current converter The output of the integrator of the above-mentioned negative side Rogowski current converter is reset to zero by detecting the timing at which the output sum of the current and the AC current detector becomes zero level. A negative reset circuit that generates a reset signal is provided, so that the DC current flowing through the positive arm and the negative arm of the two-level inverter is utilized by utilizing the rising phenomenon of the detection output of each of the other related Rogowski current converters. Current can be detected with excellent responsiveness and accuracy.

According to a fourteenth aspect of the present invention, there is provided a DC current detecting device, comprising a three-level inverter, wherein the positive side Rogowski current converter detects a current flowing through the first arm. A negative side Rogowski current converter for detecting a current flowing through the fourth arm, a neutral side detecting a current flowing between a neutral pole of the input DC power supply and the fifth and sixth diodes; Rogowski current converter, and in those having an AC current detector for detecting the AC output current, the output of the negative side Rogowski current converter and the polarity inversion output of the neutral side Rogowski current converter and A positive signal for generating a reset signal for resetting the output of the integrator of the Rogowski current converter on the positive side to zero by detecting the timing when the sum with the output of the AC current detector becomes zero level The reset circuit detects the timing at which the sum of the output of the positive-side Rogowski current converter, the output of the neutral-side Rogowski current converter, and the polarity inversion output of the AC current detector becomes zero level. A negative-side reset circuit for generating a reset signal for resetting the output of the integrator of the negative-side Rogowski current converter to zero; a polarity-inverted output of the positive-side Rogowski current converter and the negative-side Rogowski current converter; And a reset signal for resetting the output of the integrator of the Rogowski current converter on the neutral pole side to zero by detecting the timing when the sum of the output of the AC current detector and the output of the AC current detector becomes zero level. Since the pole-side reset circuit is provided, the first arm of the three-level inverter is utilized by utilizing the rising phenomenon of the detection output of each of the other associated Rogowski current converters. The fourth arm and the input DC power source neutral pole and the fifth, the DC current flowing between the sixth diode, it is possible to responsiveness, accuracy of better detection.

Further, the direct current detecting device according to the fifteenth aspect of the present invention detects the timing when the AC output current becomes zero level and inhibits the output of the reset circuit for a predetermined time from the detected timing. An erroneous reset operation based on the instantaneous fluctuation of the output current can be prevented, and the DC current detection accuracy can be kept high.

A DC current detecting apparatus according to claim 16 of the present invention adds the output of the Rogowski current converter according to claim 7 and the output of the Rogowski current converter according to claim 8, Or an adder for adding the output of the Rogowski current converter on the positive electrode side and the output of the Rogowski current converter on the negative electrode side to detect the AC output current of the two-level inverter. It has excellent responsiveness and accuracy even in the range, and can detect the AC output current of the two-level inverter at low cost.

According to a twelfth aspect of the present invention, there is provided a DC current detecting apparatus, comprising: an output of the Rogowski current converter according to claim 9; an output of the Rogowski current converter according to claim 10; 15. The output of the Rogowski current converter on the positive electrode side, the output of the Rogowski current converter on the negative electrode side, and the Rogowski current converter on the neutral pole side according to claim 14. With the addition of the adder which detects the AC output current of the three-level inverter by adding the output of
In addition, it is possible to detect the AC output current of the three-level inverter at low cost.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram showing a DC current detection device according to a first embodiment of the present invention.

FIG. 2 is an operation waveform diagram illustrating an operation of the DC current detection device of FIG.

FIG. 3 is a circuit configuration diagram showing a DC current detection device according to a second embodiment of the present invention.

4 is an operation waveform diagram illustrating an operation of the DC current detection device in FIG.

FIG. 5 is a circuit configuration diagram showing a DC current detection device according to a third embodiment of the present invention.

FIG. 6 is an operation waveform diagram illustrating an operation of the DC current detection device in FIG. 5;

FIG. 7 is a circuit configuration diagram showing a DC current detection device according to a fourth embodiment of the present invention.

8 is an operation waveform diagram illustrating an operation of the DC current detection device in FIG.

FIG. 9 is a circuit diagram showing a DC current detection device according to a fifth embodiment of the present invention.

FIG. 10 is an operation waveform diagram illustrating an operation of the DC current detection device of FIG.

FIG. 11 is a circuit diagram showing a DC current detection device according to a sixth embodiment of the present invention.

12 is an operation waveform diagram illustrating an operation of the DC current detection device in FIG.

FIG. 13 is a circuit configuration diagram showing a DC current detection device according to a seventh embodiment of the present invention.

14 is an operation waveform diagram illustrating an operation of the DC current detection device in FIG.

FIG. 15 is a circuit diagram showing a DC current detection device according to an eighth embodiment of the present invention.

FIG. 16 is an operation waveform diagram illustrating an operation of the DC current detection device in FIG.

FIG. 17 is a circuit diagram showing a DC current detection device according to a ninth embodiment of the present invention.

18 is an operation waveform diagram illustrating an operation of the DC current detection device in FIG.

FIG. 19 is a circuit diagram showing a DC current detection device according to a tenth embodiment of the present invention.

20 is an operation waveform diagram illustrating an operation of the DC current detection device in FIG.

FIG. 21 is a circuit configuration diagram showing a conventional DC current detection device.

FIG. 22 is an operation waveform diagram illustrating an operation of the DC current detection device in FIG. 21.

[Explanation of symbols]

1 DC bus, 2, 2a, 2b, 2P, 2N, 2C Rogowski coil, 3, 3a, 3b, 3P, 3N, 3C
Integrator, 4, 4a, 4b, 4P, 4N, 4C switch, 5, 5a, 5b, 5P, 5N, 5C Reset pulse generator, 6 No-current period prediction means, 6a, 6b, 6
c, 6d Gate pulse generator, 10a, 10b, 10
c, 10p, 10n DC power supply, 11a, 11b, 11
P, 11N, 11P1, 11P2, 11N1, 11N2
Self-extinguishing element, 12a, 12b, 12P, 12N, 12
P1, 12P2, 12N1, 12N2 diode, 13
a, 13b reactor, 15P, 15N diode, 16 AC output current detector, 17P, 17N, 17
P1, 17C1, 17N1 adder, 18P, 18N,
18C, 18O 0 level detector, 19, 19P, 19
C, 19N, 19O Polarity inverter, 20 off delay circuit, 21P, 21N, 21C AND circuit.

Claims (17)

[Claims] 1. A method for detecting a direct current having a non-current period by a Rogowski current converter comprising a Rogowski coil and an integrator for integrating an output of the Rogowski coil, wherein the non-current period of the direct current is predicted. And resetting the output of the integrator to zero during the predicted no-current period. 2. A direct current having a no-current period flowing through a power converter using a self-turn-off device, which is detected by a Rogowski current converter including a Rogowski coil and an integrator for integrating its output. In the current detection device, there is provided a non-current period prediction unit for predicting a non-current period of the DC current, and a reset unit for resetting an output of the integrator to zero at a prediction timing of the non-current period. DC current detector for power converter. 3. When the current to be detected of the Rogowski current converter rises due to the turn-on operation of the self-turn-off device to which the gate pulse on signal is applied, the no-current period estimating means outputs the gate pulse on timing. The direct current detection device for a power conversion device according to claim 2, wherein 4. A series connection of a self-extinguishing element and a diode connected between both poles of an input DC power supply, a reactor connected in series with an output DC power supply between both poles of the diode, and the self-extinguishing element A power converter that constitutes a step-down chopper by a gate pulse generator that supplies a gate pulse to the self-turn-off device, comprising a Rogowski current converter that detects a current flowing through the self-extinguishing element. 3. The DC current detecting device for a power converter according to claim 2, wherein an output of an integrator of said Rogowski current converter is reset to zero by detecting a timing of turning on a gate pulse from said device. 5. The non-current period estimating means outputs the gate pulse off timing when the detected current of the Rogowski current converter rises due to the turn-off operation of the self-turn-off device to which the gate pulse off signal is applied. The direct current detection device for a power conversion device according to claim 2, wherein 6. A series connection of a reactor and a self-extinguishing element connected between both poles of an input DC power supply, a diode connected in series with an output DC power supply between both poles of the self-extinguishing element, and What is claimed is: 1. A power conversion device comprising a step-up chopper comprising a gate pulse generator for supplying a gate pulse to an arc-extinguishing element, comprising a Rogowski current converter for detecting a current flowing through the diode. 3. The DC current detecting device according to claim 2, wherein an output of an integrator of the Rogowski current converter is reset to zero by detecting a timing of turning off a gate pulse from the DC converter. 7. A positive-side arm and a negative-side self-extinguishing element comprising a positive-side self-extinguishing element and a diode connected in anti-parallel to the positive-side self-extinguishing element connected between the two poles of the input DC power supply for each phase, and vice versa. A two-level inverter comprising a series connection with a negative electrode arm composed of a diode connected in parallel, and a gate pulse generator for supplying a gate pulse to the two self-extinguishing elements and taking out an AC output from a connection point between the two arms; A power converter comprising: a Rogowski current converter for detecting a current flowing to the positive electrode arm; wherein a gate pulse is supplied from the gate pulse generator to the negative electrode self-extinguishing element. 3. The power converter according to claim 2, wherein an output of the integrator of the Rogowski current converter is reset to zero by detecting the timing of the power converter. Flow current detecting device. 8. A positive arm and a negative self-extinguishing element, each comprising a positive self-extinguishing element and a diode connected in anti-parallel with the positive self-extinguishing element connected between the two poles of the input DC power supply. A two-level inverter comprising a series connection with a negative electrode arm composed of a diode connected in parallel, and a gate pulse generator for supplying a gate pulse to the two self-extinguishing elements and taking out an AC output from a connection point between the two arms; A power converter comprising: a Rogowski current converter for detecting a current flowing through the negative arm; wherein a gate pulse supplied from the gate pulse generator to the positive self-extinguishing element is turned off. 3. The power converter according to claim 2, wherein an output of the integrator of the Rogowski current converter is reset to zero by detecting the timing of the power converter. Flow current detecting device. 9. A series connection of first to fourth self-extinguishing elements connected for each phase between the positive and negative poles of an input DC power supply having a positive electrode, a neutral electrode, and a negative electrode, and each of the self-extinguishing devices. First to fourth diodes respectively connected in antiparallel with the element to form first to fourth arms, a neutral point of the input DC power supply and a connection point of the first and second arms, respectively, and 3, the fifth and sixth diodes connected between the connection point of the fourth arm and the gate pulse generator for supplying a gate pulse to each of the self-extinguishing elements. What is claimed is: 1. A power conversion device comprising a three-level inverter for extracting an AC output from a connection point of an arm, comprising a Rogowski current converter for detecting a current flowing through the first arm. Up 3. The power converter according to claim 2, wherein an output of an integrator of the Rogowski current converter is reset to zero by detecting a timing of turning off a gate pulse supplied to the third self-extinguishing element. DC current detector. 10. A series connection of first to fourth self-extinguishing elements connected for each phase between the positive and negative electrodes of an input DC power supply having a positive electrode, a neutral electrode, and a negative electrode, First to fourth diodes respectively connected in antiparallel with the element to form first to fourth arms, a neutral point of the input DC power supply and a connection point between the first and second arms and the 3, the fifth and sixth diodes connected between a connection point of the fourth arm and a gate pulse generator for supplying a gate pulse to each of the self-extinguishing elements; What is claimed is: 1. A power conversion device comprising a three-level inverter for extracting an AC output from a connection point of an arm, comprising a Rogowski current converter for detecting a current flowing through the fourth arm. 3. The power converter according to claim 2, wherein an output of an integrator of said Rogowski current converter is reset to zero by detecting a timing of turning off a gate pulse supplied to said second self-turn-off device. DC current detector. 11. A series connection of first to fourth self-extinguishing elements connected for each phase between the positive and negative electrodes of an input DC power supply having a positive electrode, a neutral electrode, and a negative electrode, and each of the self-extinguishing devices. First to fourth diodes respectively connected in antiparallel with the element to form first to fourth arms, a neutral point of the input DC power supply and a connection point of the first and second arms, respectively, and 3, the fifth and sixth diodes connected between the connection point of the fourth arm and the gate pulse generator for supplying a gate pulse to each of the self-extinguishing elements. A Rogowski detecting a current flowing between a neutral pole of said input DC power supply and said fifth and sixth diodes, said power converter comprising a three-level inverter for extracting an AC output from a connection point of an arm. Equipped with current converter In the above method, the timing of turning off the gate pulse supplied from the gate pulse generator to the first and fourth self-extinguishing elements is detected, and the output of the integrator of the Rogowski current converter is reset to zero. 3. The direct current detection device for a power converter according to claim 2, wherein: 12. The detected current of the first Rogowski current converter falls by the turn-off operation of the self-turn-off device to which the gate pulse off signal is applied, and the second
When the detected current of the Rogowski current converter rises, the detection current of the second Rogowski current converter and the output current detection value of the power converter that does not change by the turn-off operation of the self-extinguishing element are added. Find the combined current
3. The electric power according to claim 2, wherein the non-current period estimating means for resetting the output of the integrator of the first Rogowski current converter to zero outputs a timing at which the zero level of the combined current is detected. DC current detector for converter. 13. A positive-side arm and a negative-side self-turn-off element comprising a positive-side self-extinguishing element and a diode connected in anti-parallel to the positive-side self-turn-off element and a diode connected between the two poles of the input DC power supply. A two-level inverter comprising a series connection with a negative electrode side arm consisting of a diode connected in parallel, and a gate pulse generator for supplying a gate pulse to the two self-extinguishing elements and taking out an AC output from a connection point between the two arms. A power converter comprising: a positive-side Rogowski current converter for detecting a current flowing to the positive-side arm; a negative-side Rogowski current converter for detecting a current to flow to the negative-side arm; and the AC output current. And an AC current detector for detecting an output current, wherein the output sum of the negative side Rogowski current converter and the AC current detector becomes zero level. Positive-side reset circuit for generating a reset signal for detecting an output of the integrator of the positive-side Rogowski current converter and resetting the output of the integrator to zero, and outputs of the positive-side Rogowski current converter and the AC current detector 3. A negative reset circuit for detecting a timing when the sum becomes zero level and generating a reset signal for resetting an output of an integrator of the negative Rogowski current converter to zero. DC current detector of power converter. 14. A series connection of first to fourth self-extinguishing elements connected for each phase between the positive and negative poles of an input DC power supply having a positive pole, a neutral pole, and a negative pole, and each of said self-extinguishing arcs First to fourth diodes respectively connected in antiparallel with the element to form first to fourth arms, a neutral point of the input DC power supply and a connection point of the first and second arms, respectively, and 3, the fifth and sixth diodes connected between the connection point of the fourth arm and the gate pulse generator for supplying a gate pulse to each of the self-extinguishing elements. What is claimed is: 1. A power converter comprising a three-level inverter for extracting an AC output from a connection point of an arm, comprising: a Rogowski current converter on the positive electrode side for detecting a current flowing through the first arm; Negative electrode to detect Side Rogowski current converter, Neutral pole side Rogowski current converter for detecting a current flowing between the neutral pole of the input DC power supply and the fifth and sixth diodes, and detecting the AC output current Wherein the sum of the output of the negative-side Rogowski current converter, the polarity-inverted output of the neutral-side Rogowski current converter, and the output of the AC current detector is zero level. A positive-side reset circuit for detecting a timing at which the output of the positive-side Rogowski current converter is reset to zero and resetting the output of the integrator of the positive-side Rogowski current converter to zero; The timing at which the sum of the output of the negative Rogowski current converter and the polarity inverted output of the AC current detector becomes zero level is detected, and the output of the integrator of the negative Rogowski current converter is reset to zero. A negative reset circuit for generating a reset signal to be set, and a zero level sum of a polarity inverted output of the positive Rogowski current converter, an output of the negative Rogowski current converter, and an output of the AC current detector. 3. A neutral pole side reset circuit for detecting a timing at which the output of said neutral pole side Rogowski current converter is reset to generate a reset signal for resetting the output of said integrator to zero. DC current detector of power converter. 15. The power converter according to claim 13, wherein a timing at which the AC output current becomes zero level is detected, and the output of the reset circuit is inhibited for a predetermined time from the timing. DC current detector. 16. The Rogowski current converter according to claim 13, wherein the output of the Rogowski current converter according to claim 7 and the output of the Rogowski current converter according to claim 8 are added. A DC current detection device for a power converter, comprising: an adder for adding the output of the two-level inverter and the output of the Rogowski current converter on the negative side to detect the AC output current of the two-level inverter. 17. An output of the Rogowski current converter according to claim 9, an output of the Rogowski current converter according to claim 10, and an output of the Rogowski current converter according to claim 11, Or adding the output of the Rogowski current converter on the positive side, the output of the Rogowski current converter on the negative side, and the output of the Rogowski current converter on the neutral side according to claim 14 to obtain 3
A DC current detecting device for a power converter, comprising an adder for detecting an AC output current of a level inverter.