JP4615336B2 - Single-phase power converter and three-phase power converter - Google Patents

Description

  The present invention relates to a single-phase power converter and a three-phase power converter. Specifically, in a power conversion device that converts DC power into AC power, a single-phase power conversion device that suppresses a DC component contained in AC power by extracting a DC component from the output terminal voltage and correcting the target current. And a three-phase power converter.

  Many power converters have a transformer to insulate the converter from the load or to match the output of the converter to the system voltage of the load. On the other hand, if a DC component is included in the input voltage of the load-side transformer due to temperature drift or offset in the control system, the iron core of the transformer is magnetized in one direction by the DC component, and the magnetic flux distribution is Unbiased magnetism occurs. As a result, the exciting inductance of the transformer is extremely reduced, an excessive exciting current flows, the output voltage is distorted, the transformer is locally heated, the electromagnetic noise is increased, and the AC power supplied by the power converter is reduced. There was a problem of becoming unstable.

  As a method for solving such a problem, for example, a saturable reactor and a reactor that supplies an exciting current proportional to the number of flux linkages are connected in parallel to the primary side of the transformer, and a DC component is detected from the exciting current flowing through the reactor. However, a DC component suppression method is disclosed that compensates for the bias of the transformer by reducing the control to the inverter control circuit of the converter. When the DC power is not included in the AC power output from the converter, a positive / negative target current flows through the reactor, and no DC component is generated at the output of the operational amplifier that integrates the current flowing through the reactor. However, when a DC component is included, a positive and negative asymmetric current flows through the reactor, and a DC component proportional to the magnetic saturation is detected at the output of the operational amplifier. Therefore, the saturable reactor and the exciting current of the reactor Is detected and a DC component proportional to the magnetic saturation is detected by integrating for one period by an integrating circuit to compensate for the bias of the transformer. (For example, see Patent Documents 1 and 2)

  On the other hand, as a current control method for the power converter, an error tracking AC current that generates a target current by the target current generating means and performs PWM (pulse width modulation) control of the converter so that the output current tracks the target current. Control schemes have been proposed by the inventors. (For example, see Non-Patent Documents 1 and 2)

FIG. 11 shows an example of a circuit configuration of a single-phase power converter that employs an error tracking type AC current control method. Reference numeral 1 denotes a DC power source 1 (electromotive voltage E _B ) for supplying DC power. The main circuit 100 mainly includes a converter 2 that converts DC power supplied from the DC power source 1 into AC power, and wiring that allows current to flow from the converter 2 to the output terminals u1 and u2 through the inductor 3 (inductance component L _P ). and a filter circuit 5 connected between the inductor 3 and the output terminals u1 and u2 and between the output terminals u1 and u2 (between the wirings a1 and a2). The filter circuit 5 is a circuit in which a resistor R _F and a capacitor C _F are connected in series, and removes a switching frequency component included in the AC power generated by the converter 2. The converter 2 has a full bridge circuit composed of power devices (semiconductor switching elements). For example, an IGBT (insulated gate bipolar transistor) can be used as the semiconductor switch element. Reference numeral 4 denotes a load connected between the output terminals u1 and u2.

Reference numeral 18 denotes voltage detection means for detecting the filter voltage v (t) applied between the connection points of the filter circuit 5 and the wirings a1 and a2 as the output terminal voltage. Reference numeral 19 denotes first current detecting means for detecting an output current i _P (t) flowing from the converter 2 to the inductor 3. Reference numeral 7 denotes second current detecting means for detecting a load current i _S (t) flowing from the output terminals u 1 and u 2 to the load 4. The output current i _P (t) is detected from the wiring a1 or a2 near the converter 2, and the load current i _S (t) is detected from the wiring a1 or a2 near the output terminal u1 or u2. The inductor 3 is used for current control of the output current i _P (t). Reference numeral 17 denotes PWM (pulse width modulation) control means (converter control means) for controlling the converter 2, which is controlled by supplying ON / OFF signals to the gates of a plurality of semiconductor switch elements of the converter 2 in pulses. The output current i _P (t) is controlled by gate control in PWM (pulse width modulation) control means 17.

Reference numeral 110 denotes target current generating means, which calculates and generates a target current j (t) as a target value of the output current i _P (t). In the target current generating unit 110, reference numerals 13, 9, and 14 denote first, second, and third amplifiers having amplification degrees α, β, and γ that amplify a given input signal.
10 the filter voltage command means for generating a filter voltage command Vc (t) as a target value of the output terminal voltage or filter voltage v (t), 11 is a target value of the filter capacitor current C _F constituting the filter A filter current command means for generating a filter current command i _CF (= C _F (dv _c / dt), and 12 is a deviation compensation for compensating for a deviation between the output current i _P (t) and the target current j (t). PWM current deviation compensating means for generating a command D (t).

  FIG. 12 shows a processing flow of a power conversion control method in the single-phase power converter. As a process of converting DC power into AC power supplied to a load, the converter 2 converts DC power into single-phase AC power (step S001) and supplies AC power to the load 4 (step S002).

The voltage between the output terminals applied to the load 4 by the voltage detection means 18, that is, the filter voltage v (t) applied between the connection points between the filter circuit 5 and the wirings a1 and a2 is detected (step S003). The second current detection means 7 detects the load current i _S (t) flowing through the load 4 (step S004), and the first current detection means 19 converts the converter 2 to the inductor 3 (inductance component L _P the output current _i to detect the P (t) flowing in) (step S005).

Next, the control process of the target current generation unit 110 will be described.
The filter voltage command V _C (t) (step S006) generated by the filter voltage command means 10 and the filter voltage v (t) detected by the voltage detection means 18 are subtracted by the second adder 15. Then, an error is obtained (step S007), multiplied by α by the first amplifier 13 (step S008), and input to the fourth adder 16.

The load current i _S (t) detected by the second current detection means 7 is multiplied by β by the second amplifier 9 (step S 009) and input to the fourth adder 16, whereby the load current i _S (t) is input. Acts as feed forward for i _S (t).

The filter current command i _CF (step S010) generated by the filter current command means 11 is multiplied by γ by the third amplifier 14 (step S011) and input to the third adder 21.

The deviation compensation command D (t) (step S012) generated by the PWM current deviation compensation means 12 is a deviation between the target current j (t) and the actual output current i _P (t) flowing from the converter 2 to the inductor 3. intended to compensate for, is input to the third adder 21, and is added to the γ multiplied by filter current command i _CF (step S013).

In the fourth adder 16, the filter voltage error multiplied by α (filter voltage command Vc (t) −filter voltage v (t)), the load current i _S (t) multiplied by β, and the third The addition results from the adder 21 are added, and the target current j (t) is obtained as the output (step S014). The output current i _P (t) detected by the first current detector 19 is subtracted from the target current j (t) by the first adder 20 to obtain an error Δ (t) (step S015). ). The PWM control means 17 generates an on / off signal with a pulse based on the error Δ (t) obtained by the first adder 20, and supplies it to the gate of the semiconductor switch element of the converter 2. Is controlled (step S016).

Next, the case of three phases will be described. The voltage detection means 18 detects line voltages v _ab (t), v _bc (t), v _ca (t) between the three output terminals u, v, w as the output terminal voltage v (t), The output current i _p (t) detected by the first current detection means 19 has three components i _pa (t), i _pb (t), i _pc (t) corresponding to the three phases, The load current i _s (t) detected by the current detection means 7 has three components i _sa (t), i _sb (t), and i _sc (t) corresponding to the three phases. Correspondingly, the target current j (t) also has three components j _a (t), j _b (t), j _c (t), and the target current generating means 110 also performs processing for these three components.

FIG. 13 shows an example of a circuit configuration of a three-phase power converter that employs an error tracking AC current control method. In the figure, parts having the same functions as those in FIG. Differences compared to FIG. 11 will be mainly described. The converter 2 outputs a three-phase alternating current as alternating current power. The main circuit 100 includes a converter 2, three wires a, b, and c that pass current from the converter 2 to the output terminals u, v, and w through the inductor 3 (inductance components L _Pa , L _Pb , and L _Pc ), and the inductor 3. And a filter circuit 5 connected between the output terminals u, v, and w (between the wirings a, b, and c). The filter circuit 5 is constituted by a circuit connected to the resistor R _F respectively between the three capacitors C _F 3 terminals and each of the three wires a circuit connected to the delta, b, is c, single-phase As in the case, it functions as a filter that removes switching frequency components between the phases.

The voltage detection means 18 is provided in the vicinity of the filter circuit 5, and as a voltage v (t) between the output terminals, between the connection points of the filter circuit 5 and the wirings a, b, and c (that is, between ab, bc, and ca. ) To detect the filter voltage v (t) (v _ab (t), v _bc (t), v _ca (t)) applied to the first current detecting means 19 Output currents i _P (t) (i _pa (t), i _pb (t) provided in the wirings a, b, c and flowing from the converter 2 to the three inductors 3 (inductance components L _pa , L _pb , L _pc ) ), I _pc (t)), and the second current detection means 7 is provided in three wirings a, b, c near the output terminals u, v, w, and the load current i _S (t ) (I _sa (t), i _sb (t), i _sc (t)) are detected.

The signal converter 120 is a first dq converter 24 that performs dq conversion on the filter voltage v (t) (v _ab (t), v _bc (t), v _ca (t)) detected by the voltage detector 18. , And inserted between the first dq converter 24 and the second adder 15 in the target current generating means 110 and detected by the low-pass filter 25 for removing high frequency components and the second current detecting means 7. A second dq converter 26 that performs dq conversion on the generated load current i _s (t) (i _sa (t), i _sb (t), i _sc (t)), and a fourth in the target current generating unit 110. An inverse dq converter that outputs a target current j (t) (j _a (t), j _b (t), j _c (t)) by performing inverse dq conversion on the output value j _dq (t) of the adder 16 27. The first adder 20 corresponds to the three phases and outputs a three-component output current i _p (t) (i _pa (t), i _pb (t), i _pc (t)) and a target current j (t) ( _{j a (t), j b} (t), the error of the j c (t)) Δ ( t) (Δ a (t), Δ b (t), subtracts calculates Δ _c (t)), PMW control Output to means 17.

For the target current generating means 110, the filter voltage command generated by the filter voltage command means 10, the filter current command generated by the filter current command means 11, and the deviation compensation command generated by the PWM current deviation compensating means 12 are dq space. The calculation until the output value j _dq (t) is input to the inverse dq converter 27 is performed on the dq space. As for the flow of calculation, as compared with FIG. 12, the output value j _dq (t) is calculated between the calculation by the fourth adder 16 (step S014) and the calculation by the first adder (step S015). Is input to the inverse dq converter 27 and output as a target current j (t) (j _a (t), j _b (t), j _c (t)). Note that the processing in the dq space is performed for convenience of calculation.

  Note that the second current detection means 7, the first current detection means 19 and the voltage detection means 18 do not need to detect in all three phases, but may detect at least two phases, and FIG. The inside () means that it can be omitted.

JP-A-5-316754 (paragraphs 0007 to 0014, FIGS. 1 to 6 etc.) JP-A-6-217559 (paragraphs 0007-0013, FIGS. 1-7, etc.) Masaaki Oshima, “Error tracking AC current waveform control method in single-phase self-excited voltage-type AC / DC converter”, IEEJ Transactions, Vol. 114, No. 3, pages 289-298, 1994 Masaaki Oshima, Bunori Nakamura, Shinzo Tamai, Kazumasa Yamamoto, Koichi Yoshida, “Inverter for three-phase UPS with error-following PWM as a minor loop”, IEEJ Journal, Vol. 125, February 163-173, 2005

  However, in the conventional DC component suppression method using a saturable reactor or the like, the peak value of the positive and negative asymmetrical values of the saturable reactor and the exciting current of the reactor is detected, and the integration circuit is integrated for one period and is proportional to the magnetic saturation amount. Since the component was detected, there was a problem that the response was slow. Further, since there is variation in the production of the saturable reactor and the reactor, it is difficult to improve the accuracy of correcting the DC component. Furthermore, since the saturable reactor and the reactor are large, there is a problem that the apparatus is enlarged.

  In addition, power converters that employ an error-following AC current control system precisely control the current flowing through the load, so large parts such as reactors are not used, resulting in high-speed response, high accuracy, and downsizing of the device. Although it is suitable, there is a problem that during operation of the power converter, a DC component is also generated due to temperature drift of the current loop, and the DC component is amplified by the control means, and a DC component is generated at the output of the main circuit. It was found. Generally, in order to obtain a desired voltage required for a load connected to the output terminal of the main circuit, a transformer is often provided between the main circuit and the load. If there is a direct current component in the transformer, problems such as transformer biasing will occur. For this reason, it was necessary to suppress the direct current component.

Here, the influence of a direct current component is demonstrated about a single phase power converter device.
In the conventional example, the target current j (t) obtained in step S014 of FIG. 12 is expressed as (Equation 1).
j (t) = α (v _C (t) −v (t)) + βi _S (t) + γC _F (dv _C / dt) + D (t) (Equation 1)
When the direct current component _ID is generated in the target current j (t) represented by the above formula, it is represented by the following formula.
j (t) = α (v _C (t) −v (t)) + βi _S (t) + γC _F (dv _C / dt) + D (t) + _ID (Expression 2)
When the above equation is expanded, it is expressed as (Equation 3).
j (t) = α ((v _C (t) + ( _ID / α)) − v (t)) + βi _S (t) + γC _F (d / dt (v _C (t) + ( _ID / α) ))) + D (t) (Formula 3)
Therefore, the effect of the DC component _ID generated on the target current j (t) is equivalent to biasing the filter voltage command v _C (t) by _ID / α [V].

On the other hand, the filter voltage v ₀ (t) at the time of no load of the single-phase power converter is expressed as (Equation 4).
v ₀ (t) = v _C (t) + R _F C _F (dv _C / dt) (t) (Equation 4)
Since the target filter voltage v _C (t) becomes v _C (t) + I _D / α, the filter voltage v ₀ (t) at the time of no load is expressed as (Equation 5).
v ₀ (t) = v _C (t) + R _F C _F (dv _C / dt) (t) + I _D / α (Formula 5)
Eventually, the DC component V _D generated in the no-load filter voltage v ₀ (t) is expressed as (Equation 6).
V _D = I _D / α [V] (Formula 6)
As a result, it can be seen that a larger feedback gain α is more advantageous from the viewpoint of DC component suppression.

From the above, how much the DC component V _{D of the} voltage between the output terminals of the single-phase power converter changes due to the DC component _ID existing in the target current j (t), that is, the DC component V _D is suppressed. To this end, it is understood how much the target current j (t) should be changed.

The influence of the direct current component in the case of three phases can be estimated in the same manner as in the case of a single phase.
When the direct current components of the target currents ja (t), jb (t), and jc (t) are I _aD , I _bD , and I _cD (I _aD + I _bD + I _cD = 0), respectively, the line of the three-phase power converter DC components V _abD , V _bcD , and V _caD generated in the inter-voltages (inter-terminal output voltage, filter voltage) v _ab (t), v _bc (t), and v _ca (t) are _expressed by (Equation 7a) to (Expression 7c)
V _abD = (I _aD −I _bD ) / α [V] (Formula 7a)
V _bcD = (I _bD −I _cD ) / α [V] (Formula 7b)
V _caD = (I _cD −I _aD ) / α [V] (Formula 7c)

FIG. 14 shows the experimental results when the DC component is added to the target current in the three-phase power converter that does not take the DC component suppression measure of FIG. The load condition is no load. The lower column shows the pulse signal (on / off signal) supplied to the gate of the semiconductor switch element of the converter 2, and the upper column shows the line voltages v _ab (t), v _bc (t), v _ca (t) and the line voltage. Shows a d-axis component V _d and a q-axis component V _q obtained by dq conversion. The horizontal axis is time (ms). The waveform before adding the DC component is indicated by a solid line, and the waveform after adding the DC component is indicated by a dotted line. As can be seen from FIG. 14, the DC voltage is biased to the positive side of the line voltage v _ab (t) and the negative side of v _ca (t) (the bias direction is indicated by an arrow). It can be considered that v _bc (t) is not biased. Further, the average value of _{V d} component corresponding to the DC component _{V D} was _applied, V d, the _{V q} component has arisen 50Hz component.

  From the above, it can be understood that in order to suppress the DC component of each line voltage of the power conversion device, correction for removing the DC component from the target current of each phase may be performed.

  The present invention provides a power converter that can suppress the DC component contained in the AC power output from the power converter without using a large component such as a reactor, and can reduce the size of the device with high speed response and high accuracy. The purpose is to do.

In order to solve the above-described problem, a single-phase power converter according to a first aspect of the present invention generates single-phase AC power from a DC power source 1 and outputs it to output terminals u1 and u2, for example, as shown in FIG. A single-phase power converter for supplying power to a connected load 4, a converter 2 for converting DC power from a DC power source 1 into single-phase AC power, and an inductor connected to the AC side of the converter 2 3, first current detection means 19 for detecting the output current i _P (t) flowing through the inductor 3, and voltage detection means for detecting the output terminal voltage v (t) applied between the output terminals u 1 and u 2. 18, a target current generation means 110 for generating a target current j as the target value of the output current _{i P (t) (t)} , the output current _i P (t) and the error between the target current j (t) delta ( converter control means for controlling the pulse width of the converter 2 based on t) 7, the target current generation means 110 amplifies the integrated value of the output terminal voltage v (t) detected by the voltage detection means 18 and corrects the target current j (t), thereby obtaining a single phase. DC component suppression means 8 for suppressing a DC component included in AC power is included.

Moreover, the invention according to the second aspect of the present invention is the single-phase power converter according to the first aspect . For example, as shown in FIG. 1, the single-phase AC power is connected between the output terminals u1 and u2. The voltage detecting means 18 detects the filter voltage applied to the filter circuit 5 as the output terminal voltage v (t), and the first DC component suppressing means. 8 amplifies the integral value of the filter voltage v (t) to correct the target current j (t).

In addition, the single-phase power converter according to the third aspect of the present invention generates a single-phase AC power from the DC power source 1 and applies it to the load 4 connected to the output terminals u1 and u2, as shown in FIG. A single-phase power converter for supplying power, comprising a converter 2 for converting DC power from a DC power source 1 into single-phase AC power, an inductor 3 connected to the AC side of the converter 2, and an inductor 3 First current detection means 19 for detecting the flowing output current i _P (t), voltage detection means for detecting the output terminal voltage v (t) applied between the output terminals u1, u2, and the output current i _P Based on the target current generating means 110 for generating the target current j (t) as the target value of (t) and the error Δ (t) between the output current i _P (t) and the target current j (t) Converter control means 17 for controlling the pulse width modulation of the device 2, 18 is composed of a capacitor C _d between the output terminals u1, u2 and resistance R _d from the circuit connected in series, the DC voltage detecting means for detecting a DC voltage component V _D applied between the output terminals u1, u2 6 And the target current generating means 110 corrects the target current j (t) based on the DC voltage component V _D , thereby providing the DC component suppressing means 8 that suppresses the DC component included in the single-phase AC power. Have.

Further, the invention according to the fourth aspect of the present invention is the single-phase power conversion device according to the third aspect . For example, as shown in FIG. 8, the DC component suppression means 8 is detected by the DC voltage detection means 6. Amplifying means 34 for amplifying the direct current component, and determination means 39 for judging the polarity of the voltage value of the direct current component, adding a sign based on the judgment result, and outputting the result.

Moreover, the three-phase power converter according to the fifth aspect of the present invention generates a three-phase AC power from a DC power source 1 and is connected to output terminals u, v, and w as shown in FIG. 4 is a three-phase power converter for supplying power to a converter 2, which converts DC power from a DC power source 1 into three-phase AC power, an inductor 3 connected to the AC side of the converter 2, and an inductor 3 is applied between the current detection means 19 for detecting the output current i _P (t) (i _pa (t), i _pb (t), i _pc (t)) flowing through the output terminals u, v, and w. Voltage detection means 18 for detecting the output terminal voltage v (t) (v _ab (t), v _bc (t), v _ca (t)), and the output current i _P (t) (i _pa (t), Target current generating means for generating a target current j (t) as a target value of i _pb (t), i _pc (t)) 110 and an error Δ (t) (Δ _a (t),) between the output current i _P (t) and the target current j (t) (j _a (t), j _b (t), j _c (t)). Based on Δ _b (t), Δ _c (t)), the converter 2 is provided with converter control means 17 for controlling the pulse width of the converter 2, and the target current generation means 110 is output detected by the voltage detection means 18. The integrated value of the inter-terminal voltage v (t) (v _ab (t), v _bc (t), v _ca (t)) is amplified, and the target current j (t) (j _a (t), j _b ( By correcting t), j _c (t)), there is a DC component suppression means 8 that suppresses a DC component included in the three-phase AC power.

Further, the invention according to the sixth aspect of the present invention is the three-phase power converter according to the fifth aspect , wherein the three-phase power converter is connected between the output terminals u, v, and w, for example, as shown in FIG. The filter circuit 5 for removing the switching frequency component contained in the AC power is provided, and the voltage detection means 18 is used as a voltage between the output terminals between the connection points of the filter circuit 5 and the wirings a, b, c (that is, between ab, bc The filter voltage v (t) (v _ab (t), v _bc (t), v _ca (t)) applied between the dc component and _ca is detected, and the DC component suppression means 8 detects the filter voltage v (t ) (V _ab (t), v _bc (t), v _ca (t)) is amplified to obtain a target current j (t) (j _a (t), j _b (t), j _c ( t)) is corrected.

Moreover, the three-phase power converter according to the seventh aspect of the present invention is a load that generates three-phase AC power from a DC power source 1 and is connected to output terminals u, v, and w, for example, as shown in FIG. 4 is a three-phase power converter for supplying power to a converter 2, which converts DC power from a DC power source 1 into three-phase AC power, an inductor 3 connected to the AC side of the converter 2, and an inductor 3 between the output terminals u, v, w and the first current detection means 19 for detecting the output current i _P (t) (i _pa (t), i _pb (t), i _pc (t)) Voltage detection means for detecting the applied output terminal voltage v (t) (v _ab (t), v _bc (t), v _ca (t)), and output current i _P (t) (i _pa (t _), i pb _(t), the target current _j as the target value of _{i pc (t)) (t} ) (j a (t), j b ( _), J and the target current generation means 110 for generating a c (t)), the output current _{i P (t) (i pa} (t), i pb (t), i pc (t)) between the target current j (t ) (J _a (t), j _b (t), j _c (t)) and an error Δ (t) (Δ _a (t), Δ _b (t), Δ _c (t)), Converter control means 17 for controlling the converter 2 for pulse width modulation, and the voltage detection means 18 is composed of a circuit in which a capacitor _Cd and a resistor _Rd are connected in series between output terminals u, v, and w. A DC voltage detection unit 6 that detects a DC voltage component V _D (V _abD , V _cbD ) applied between the output terminals u, v, and w is _provided , and the target current generation unit 110 includes a DC voltage component V _D (V _ABD, based on _{V CBD),} the target current _{j (t) (j a (} t), j b (t), to correct the j c (t)) More has a suppressing DC component suppression means 8 the DC component included in the three-phase AC power.

Further, the invention according to the eighth aspect of the present invention is the three-phase power converter according to the seventh aspect , wherein the DC component suppression means 8 is detected by the DC voltage detection means 6 as shown in FIG. are two DC component _{V ABD,} a first addition means 37a for adding the amplification means 34a, 34b for amplifying the _{V CBD,} and 2 times the first DC component _{V ABD} and second DC component _{V CBD} The second adding means 37b for adding the first DC component V _abD and twice the second DC component V _cbD and the polarity of the voltage value added by the first adding means 37a are determined and determined. The polarity of the voltage value added by the first determination means 39a and the second addition means 37b, which are attached with a sign based on the result and output, is determined, and the sign is output based on the determination result. 2 determination means 39b.

In the claims of the present application, the output terminal voltage v (t) refers to a voltage applied between the output terminals, but a voltage substantially equivalent to this, for example, the filter circuit 5 connected between the output terminals, etc. The voltage applied to is included. In this case, for example, if there is no substantial influence on the output terminal voltage v (t) in the middle of the wiring connecting the output terminals u 1 and u 2 and the inductor 3, the output terminals u 1 and u 2 and the inductor 3 are connected. You may provide the filter circuit 5 in the arbitrary positions of wiring. Further, the detection of the output terminal voltage v (t) may be configured to detect the DC component V _D directly. Further, the target current generation unit 110 includes the DC component suppression unit 8. In this case, the DC component suppression unit 8 may be physically provided outside the target current generation unit 110. Further, even when a transformer is connected as the load 4 and the wiring is directly connected to the winding of the transformer, it is assumed that there is an output terminal between the power converter and the transformer.

  Further, regarding the three-phase power converter, the three phases are represented in correspondence with the currents, that is, the wirings a, b, and c. Further, the output terminal voltage, the filter voltage, the output current, the target current, and the error refer to a voltage and current including three components. Further, the filter circuit 5 may exist independently as a separate circuit between the wirings, and one circuit is connected to each wiring and functions to remove the switching frequency component between the respective wirings, that is, between the phases. But it ’s okay. Each means such as the integrating means and the multiplying means in the DC component suppressing means 8 may exist as a separate circuit, or may be integrated or divided.

  According to the present invention, the target current is generated by using the target current generating unit, the DC component contained in the AC power is detected by the voltage detecting unit, and the target current is corrected, so that a large component such as a reactor is used. Therefore, it is possible to provide a power conversion device that can suppress a direct current component included in the AC power output from the power conversion device and can downsize the device with high speed response and high accuracy.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a circuit configuration example of a single-phase power converter according to the first embodiment of the present invention. 1, parts having the same functions as those in FIG. Compared to FIG. 11, the output of the fourth adder 16 is changed from the target current to the primary target current j ₁ (t), and is filtered as a detection signal from the voltage detection means 18 in the target current generation means 110. type voltage v a (t), the target current and the DC component suppression means 8 calculates a correction amount _j h (t) of j (t), the correction amount _j h (t) of the primary target current _j 1 (t ), And a fifth adder 22 for outputting the target current j (t) to the first adder 20 is added. Correction filter voltage v (t), i.e., is performed in order to suppress the DC component V _D included in the voltage between the output terminals.

That is, the power conversion device according to the present embodiment is a single-phase power conversion device that generates single-phase AC power from a DC power source 1 and supplies power to a load 4 connected to output terminals u1 and u2. A converter 2 that converts DC power from the power source 1 into single-phase AC power, an inductor 3 connected to the AC side of the converter 2, and a first current that detects an output current i _P (t) flowing through the inductor 3 A current detection means 19, a voltage detection means 18 for detecting a voltage v (t) between the output terminals applied between the output terminals u1 and u2, and a target current j (t as a target value of the output current i _P (t) ), And converter control means 17 for performing pulse width modulation control on the converter 2 based on the error Δ (t) between the output current i _P (t) and the target current j (t). The target current generating means 110 includes a voltage detection DC component suppression means 8 that suppresses the DC component contained in the single-phase AC power by correcting the target current j (t) based on the integrated value of the output terminal voltage v (t) detected in the stage 18. Have

The characteristic feature of the DC component suppression in the present embodiment, integrated by detecting the output terminal voltage v (t), obtains a value obtained by multiplying the integrated value by the gain 1 / L _F, the DC component A correction amount j _h (t) to be corrected is added, and the correction amount j _h (t) is added (substantially reduced) to the target current j (t), and further, an error between the target current j (t) and the output current. Δ (t) is obtained and input to the PWM control means 17, and the converter 2 is controlled based on the error Δ (t). In this integration, sampling values may be integrated digitally, or voltage values may be integrated analogically. In this way, the DC component V _D can be suppressed by adding (substantially subtracting) the correction amount j _h (t) to the primary target current j ₁ (t).

  If comprised in this way, the power converter which can suppress the direct current component contained in the alternating current power output from a power converter device without using big parts like a reactor, and can miniaturize a device with high-speed response and high accuracy Can provide.

The filter circuit 5 is composed of a circuit in which a capacitor C _F and a resistor R _F are connected in series, and the voltage detection means 18 is connected between the connection points of the filter circuit 5 and the wirings a1 and a2 as the output terminal voltage v (t). The filter voltage applied to is detected. In addition, second current detection means 7 for detecting a load current i _S (t) flowing through the load 4 is provided. Target current generation means 110 includes a filter voltage command means 10 for generating a filter voltage command v _{C (t)} as the target value of the filter voltage v (t), as the target value of the filter current i _Cf flowing through the capacitor C _F Deviation compensation to compensate for the current deviation between the filter current command means 11 for generating the filter current command i _CF (= C _F (dv _C / dt)) and the output current i _P (t) and the target current j (t). Current deviation compensation means 12 for generating a command D (t), based on a filter voltage command v _C (t), a filter current command i _CF , a deviation compensation command D (t), and a correction amount j _h (t). The target current j (t) is calculated. The PWM control means 17 (converter control means) supplies on / off signals to a plurality of semiconductor switch elements based on the error Δ (t). Here, the second current detection means 7, the filter current command i _CF , and the deviation compensation command D (t) can be omitted. Further, the filter circuit 5 may be a circuit obtained by removing the resistor R _F from the circuit of this embodiment.

In addition, the target current generation unit 110 includes a second adder 15 that performs subtraction between the primary voltage v (t) detected by the voltage detection unit 18 and the filter voltage command v _C (t), and a second addition. A first amplifier 13 for amplifying the error output from the multiplier 15 by a factor, a second amplifier 9 for amplifying the load current i _S (t) detected by the first current detector 7 by a factor of β, and a filter The third amplifier 14 for amplifying the current command i _CF by γ times, the third adder 21 for adding the output signal from the third amplifier 14 and the deviation compensation command D (t), and the first amplifier 13 A fourth adder 16 for adding the output signal from the second amplifier 9, the output signal from the second amplifier 9, and the output signal from the third adder 21 to calculate the primary target current j ₁ (t); primary target current _j 1 (t) of the correction amount _j adds h (t) and the target current j (t) Calculated by the first adder 20 having a fifth adder 22 and supplies. In addition, the power converter performs subtraction between the output current i _P (t) detected by the first current detection unit 19 and the target current j (t) outside the target current generation unit 110, and the difference is obtained. There is provided a first adder 20 that supplies the converter control means 17 as an error Δ (t).

FIG. 2 shows an example of a processing flow of the DC component suppression method for the power conversion device in the present embodiment. First, the process added to FIG. 12 is demonstrated and the overlapping description is abbreviate | omitted. The added flow is indicated by a double line in the figure. In order to suppress the DC component V _D generated in the filter voltage v (t), the DC component suppression means 8 integrates the filter voltage v (t) detected by the voltage detection means 18 to obtain an integrated value (step S017). ), The obtained integral value is multiplied by a gain (−1 / L _F ) to obtain a correction amount j _h (t) (step S018). That is, the AC component is canceled by integrating the filter voltage v (t) detected by the voltage detection means 18, and the DC component is extracted. The correction amount j _h (t) is expressed as (Equation 8a), and when j _h (t) is converted into a function using the Laplace operator s as a variable, it is expressed as (Equation 8b). The fifth adder 22 adds the correction amount j _h (t) to the primary target current j ₁ (t) and outputs the target current j (t) (step S019).

Here, L _F is the inverse of the gain, with the dimensions of the inductance. When a transformer is connected to the load 4, the value of L _F needs to be smaller than the exciting inductance of the transformer, while it needs to be greater than a certain predetermined value so as not to cause resonance with the filter circuit 5. There is also. The value of L _F is a main circuit configuration, the operating conditions of the power converter, for varies depending on the load conditions, but categorically can not decide, because alpha · L _F is the time constant of the DC component suppression gain the value of 1 / L _F, it is desirable that the value of alpha · L _F is set to be about 1 second from about 0.01 seconds in terms of the polarization磁耐of the transformer.

That is, the direct current component suppression method for the power conversion device according to the present embodiment is a direct current component suppression method for a power conversion device that converts direct current power and supplies alternating current power. The converter 2 converts the direct current power into alternating current power. Conversion step (step S001) for conversion, power supply step (step S002) for supplying AC power to the load 4, and voltage detection for detecting the output terminal voltage v (t) applied between the output terminals u1 and u2. A step (step S003), a current detection step (step S005) for detecting the output current i _P (t) flowing from the converter 2 to the inductor 3 on the wiring, and a target as a target value of the output current i _P (t) A target current generating step (step S014) for outputting the current j (t), and a converter for controlling the converter 2 based on the error Δ (t) between the output current i _P (t) and the target current j (t) System And the target current generation step (step S014) includes a target current j (t) for suppressing a DC component contained in the AC power based on the detection signal detected in the voltage detection step. correction amount _j h (t) correction amount calculating step of calculating (step S017~ step S018), the correction amount _j h correcting step for correcting the target current j (t) using (t) (step S019) Have

  If comprised in this way, the direct-current component contained in the alternating current power output from a power converter device can be suppressed.

Next, a three-phase power conversion device will be described as a second embodiment of the present invention. In the case of three phases, the basic countermeasures for DC component suppression are the same as in the case of a single phase. In the case of a three-phase power converter, correction amounts j _ha (t) and j _hb (t) are respectively applied to the three target currents j _a (t), j _b (t), and j _c (t). , J _hc (t) may be calculated and corrected, and the same DC component suppression measures as in the case of a single phase can be applied.

Corresponding to the three phases, the voltage detection means 18 uses the line voltages v _ab (t), v _bc (t), v _ca between the three output terminals u, v, w as the output terminal voltage v (t). (T) is detected, and the output current i _p (t) detected by the first current detection means 19 has three components i _pa (t), i _pb (t), i _pc (t), The load current i _s (t) detected by the current detection means 7 has three components i _sa (t), i _sb (t), and i _sc (t). The target current generating unit 110 also performs processing for these three components.

FIG. 3 shows a circuit configuration example of the three-phase power converter in the second embodiment. In the figure, portions having the same functions as those in FIGS. 1 and 13 are denoted by the same reference numerals, and different points will be mainly described. 3 differs from FIG. 13 in that the direct current component suppression unit 8 and the fifth adder 22 are inserted in the output side of the inverse dq converter 27 in the target current generation unit 110. Also, the target current j _dq (t) output from the fourth adder 16 in the dq space is _subjected to inverse dq conversion by the primary target current j _dq1 (t) in the dq space and the inverse dq converter 27. The target current j (t) output in this way is paraphrased as the primary target current j ₁ (t) (j _a1 (t), j _b1 (t), j _c1 (t)). The signal conversion means 120 is functionally similar to FIG. When the output component voltage v (t) detected by the voltage detection unit 18 is input, the direct current component suppression unit 8 calculates the target current correction amount j _h (t) and supplies it to the fifth adder 22. Then, the fifth adder 22 adds the correction amount j _h (t) to the primary target current j ₁ (t) output from the inverse dq converter 27 to obtain the target current j (t). Output. The first embodiment (see FIG. 1) is different from the first embodiment in that the target current j (t) has three components, and for the convenience of calculation, the target current generation unit 110 and the like perform calculation processing in the dq space. The point is different. In addition, () in FIG. 3 means that it can be omitted.

That is, the power conversion device in the present embodiment is a three-phase power conversion device that generates three-phase AC power from a DC power source 1 and supplies power to the load 4 connected to the output terminals u, v, and w. , A converter 2 for converting DC power from the DC power source 1 into three-phase AC power, an inductor 3 connected to the AC side of the three-phase converter 2, and an output current i _P (t) (i) flowing through the inductor 3 first current detecting means 19 for detecting _pa (t), i _pb (t), i _pc (t)), and output terminal voltage v (t) (v _ab (t), v _bc (t), voltage detection means 18 for detecting v _ca (t)), and target current j () as a target value of output current i _P (t) (i _pa (t), i _pb (t), i _pc (t)) t) (target current generating means 110 for generating (j _a (t), j _b (t), j _c (t)); , Pulse the converter 2 based on the error Δ (t) (Δ _a (t), Δ _b (t), Δ _c (t)) between the output current i _P (t) and the target current j (t). PWM control means 17 (converter control means) that performs width modulation control, and the target current generation means 110 outputs the output terminal voltage v (t) (v _ab (t), v _bc detected by the voltage detection means 18. By correcting the target current j (t) (j _a (t), j _b (t), j _c (t)) based on the integral value of (t), v _ca (t)), three-phase DC component suppression means 8 for suppressing a DC component included in AC power is included.

  With this configuration, even in three-phase AC, the DC component contained in AC power output from the power conversion device can be suppressed without using large components such as a reactor, and the device can be operated with high speed response and high accuracy. A power converter that can be miniaturized can be provided.

In describing the three phases, notations such as target current j (t), output current i _P (t), load current i _s (t), output terminal voltage v (t), error Δ (t), etc. As described above, it is assumed that three components are included even if three components are not particularly described.

The filter circuit 5 is connected three capacitors C _F in delta, have circuitry connected each wire (a, b, c) and through a respective resistor R _F each of its terminals, the voltage detecting means 18 detects the filter voltage applied between the connection points of the filter circuit 5 and the wirings a, b, and c as the output terminal voltage v (t). In addition, second current detection means 7 for detecting a load current i _S (t) flowing through the load 4 is provided. Also, the target current generation means 110 includes a filter voltage command means 10 for generating a filter voltage command as the target value v of the filter voltage _{v (t) C (t)} , as the target value of the filter current flowing through the capacitor C _F Filter current command means 11 for generating a filter current command i _CF, and current deviation compensation means for generating a deviation compensation command D (t) to compensate for a deviation between the output current i _P (t) and the target current j (t) The target current j (t) is calculated based on the filter voltage command v _C (t), the filter current command i _CF , the deviation compensation command D (t), and the correction amount j _h (s). The PMW control means 17 supplies an on / off signal to the plurality of semiconductor switch elements based on the error Δ (t).

Further, the target current generation means 110 performs subtraction between the output terminal voltage v (t) output from the voltage detection means 18 via the first dq converter 24 and the filter voltage command v _C (t). 2 adder 15, first amplifier 13 that amplifies the error Δ (t) output from second adder 15 by α, and load current i _s (output from second dq converter 26). The second amplifier 9 for amplifying t) by β times, the third amplifier 14 for amplifying the filter current command i _CF by γ times, the deviation compensation command D (t) and the output signal from the third amplifier 14 are added. The third adder 21, the output signal from the first amplifier 13, the output signal from the second amplifier 9, and the output signal from the third adder 21 are added to obtain a first order in the dq space. fourth adder to calculate target current _{j dq1} a (t) is output to the inverse dq converter 27 6, the first adder calculates the target current j (t) by adding the correction amount j _{h (t)} in the primary target current j ₁ is the output signal from the inverse dq converter 27 _(t) And a fifth adder 22 that supplies the signal 20. In addition, the power converter performs subtraction between the output current i _P (t) detected by the first current detection unit 19 and the target current j (t) outside the target current generation unit 110, and an error Δ A first adder 20 for supplying (t) to the converter control means 17 is provided.

The first current detection means 19 only needs to detect two or more output currents out of the output current i _p (t) flowing through each phase, and the second current detection means 7 is the load current flowing through each phase. It is only necessary to detect two or more load currents out of i _S (t), and the voltage detecting means 18 is between two or more output terminals among the output terminal voltage (line voltage) v (t) applied between the lines. What is necessary is just to detect a voltage. Further, the second current detecting means 7, the filter current command i _CF , and the deviation compensation command D (t) can be omitted. In addition, the filter circuit 5 has been described as being configured by a circuit in which a resistor R _F is connected between each terminal in which three capacitors C _F are connected in a delta shape and three wirings a, b, c. You may comprise by the circuit which connected resistance R _F between each terminal which connected three capacitor | condensers _CF in star shape, and each three wiring a, b, c. The filter circuit 5 may be the circuit of the present embodiment or a circuit obtained by removing the resistor R _F from the above circuit. In addition, the order of the first dq converter 24 and the low-pass filter 25 can be changed. Further, the order of the fifth adder 22 and the inverse dq converter 27 is changed, and the signal of the output terminal voltage v (t) detected by the voltage detection means 18 is passed through the first dq converter 24 and then DC. The target current j (t) may be input to the first adder 20 by supplying the component suppression means 8 and correcting the target current j _dq1 (t) in the dq space and performing inverse dq conversion. Further, αβ conversion may be used instead of dq conversion, and coordinate conversion may not be performed.

  The processing flow of FIG. 2 is applied as it is to the calculation for obtaining the target current.

In order to calculate the target current correction amount j _h (t), DC components V _abD , V _cbD , and V _caD are obtained from the integrated values of the line voltages (filter voltages) v _ab (t) and v _cb (t). The correction values j _ah (t), j _bh (t), and j _ch (t) are calculated using the integrated values. Here, when the correction amounts j _ah (t), j _bh (t), and j _ch (t) are Laplace transformed and expressed using the Laplace operator s, (Expression 9a) to (Expression 9c) are obtained. .
j _ah (s) = − (2/3) · (v _ab (s) / (L _F · s)) + (1/3) · (v _cb (s) / (L _F · s)) ·· (Formula 9a)
j _bh (s) = (1/3) · (v _ab (s) / (L _F · s)) + (1/3) · (v _cb (s) / (L _F · s))... (Formula 9b)
j _ch (s) = (1/3) · (v _ab (s) / (L _F · s)) − (2/3) · (v _cb (s) / (L _F · s))... (Formula 9c)

FIG. 4 is a diagram illustrating an example of processing of the DC component suppressing unit 8 in the second embodiment. Correction amounts j _ah (t) and j _ch (t) are obtained from the line voltages v _ab (t) and v _cb (t), and a flow is formed according to (Equation 9a) and (Equation 9c). ing. The DC component suppression unit 8 includes integration units 31 a and 31 b, multiplication units 32 a and 32 b, and a correction amount calculation unit 33. Two integrating means and two multiplying means are provided. The integrating means 31a and 31b obtain respective integrated values for the two output terminal voltages (line voltage, filter voltage) v _ab (t) and v _cb (t) detected by the voltage detecting means 18, and multiplying means 32a. , 32b multiply the obtained two integral values by a gain (1 / L _F ), respectively, and the correction amount calculation means 33 divides each multiplication result obtained by the gain multiplication into 1/3 and 2/3, Each of the divided multiplication results is added or subtracted (specifically, the operations of (Equation 9a) and (Equation 9c) are performed) to obtain correction amounts j _ah (t) and j _ch (t), and the sign is Inverted and input to the fifth adder 22 shown in FIG. The correction amount j _bh (t) is obtained from j _ah (t) and j _ch (t) using (Equation 9b).

The correction amounts j _ah (t), j _bh (t), and j _ch (t) obtained by the DC component suppression means 8 are the primary target currents j _a1 (t) and j _b1 by the fifth adder 22. The target currents j _a (t), j _b (t), and j _c (t) are calculated by adding to (t) and j _c1 (t). Further, in the first adder 20, the target currents j _a (t), j _b (t), j _c (t) and the output currents i _pa (t), i _pb detected by the first current detecting means 19 are detected. (T), i _pc (t), and errors Δ _a (t), Δ _b (t), Δ _c (t) are calculated and input to the PWM control unit 17, and the PWM control unit 17 determines the error Δ _a The semiconductor switch element of the converter 2 is controlled based on (t), Δ _b (t), and Δ _c (t).

FIG. 5 intentionally uses the three-phase power converter of FIG. 3 according to the second embodiment to intentionally apply a direct current component (I) to the target currents j _a (t), j _b (t), and j _c (t). _{aD = 1A, I bD = -2A} , shows the experimental results when adding I cD = 1A). The lower column shows the pulse signal (on / off signal) supplied to the gate of the semiconductor switch element of the converter 2, and the upper column shows the line voltages v _ab (t), v _bc (t), v _ca (t) and the line voltage. Represents a DC component (d-axis component V _d , q-axis component V _q ) obtained by dq conversion, and the horizontal axis represents time. The load conditions are the same as in the experiment of FIG. The DC component is added at the time indicated by the dotted line orthogonal to the horizontal axis (near 5 ms) in FIG. The waveform before adding the DC component is indicated by a solid line, and the waveform after adding the DC component is indicated by a dotted line. The DC component (V _d , V _q ) has a 50 Hz component, but this amplitude gradually decreases in about 120 ms, and the line voltages v _ab (t), v _bc (t) , V _ca (t), the direct current component (difference between solid line and broken line, ie, bias) gradually converges to zero. In this example, the DC component of the line voltage immediately after adding the DC component was 5.278V between ab and -5.347V between bc, but when it became a steady state several seconds later. When the DC component of the line voltage was measured, it was 1.3 mV between ab and 26.3 mV between bc. In this measurement result, for example, 26.3 mV between bc is 0.005% of the rated line voltage of 200 V, which is considered to be within the error range, and the DC component is sufficiently suppressed. It can be seen that

6, after the circuit of FIG. 3 is steadily operated, a direct current component is intentionally added to the target currents j _a (t), j _b (t), j _c (t), and a transformer is used as the load 4. The result of conducting an experiment of the transient response of the transformer current is shown. Three single-phase transformers were used as transformers. FIG. 6A shows the waveform of the current flowing through the single-phase transformer immediately after the DC current is applied (in a state where the magnetization is generated), and FIG. Shows the current waveform flowing in the single-phase transformer. The horizontal axis represents time (10 ms / div). From FIG. 6 (A), immediately after the DC current is applied (when the trigger signal shown in the upper part of FIG. 6 (A) changes from L level (0 V) to H level), the single-phase transformer is demagnetized. It can be seen that the peak value of the current of the single-phase transformer rises excessively, and the positive / negative symmetry of the current waveform is broken. However, from FIG. 6B, even when the DC component is continuously added (the trigger signal shown in the upper part of FIG. 6B is in the H level), the DC current is applied (when the trigger signal changes). After a few seconds, it can be seen that the current of the single-phase transformer returns to a normal value before demagnetization, the symmetry of the current waveform is restored, and the DC component is suppressed.

FIG. 7 shows a circuit configuration example of the single-phase power converter according to the third embodiment. In FIG. 7, parts having the same functions as those in FIG. Differences compared to FIG. 1 will be mainly described. A DC voltage detecting means 6 is inserted between the filter circuit 5 and the second current detecting means 7, and the DC voltage detecting means 6 detects the DC component V _D of the output terminal voltage v (t). The DC component suppression means 8 inputs the DC component V _D of the output terminal voltage v (t) detected by the DC voltage detection means 6 instead of inputting the filter voltage detected by the filter circuit 5. The difference is that the target current correction amount j _h (t) is calculated. DC voltage detection unit 6 is provided between the filter circuit 5 and the current detecting means 7, the resistance R _d and a capacitor C _d between wire a1 and a2 are connected in series, intermediate between the resistance R _d and a capacitor C _d From the point, the DC component V _D included between the wirings a1 and a2 is detected. Since these direct current components are also included in the output terminal voltage v (t), the direct current voltage detection means 6 functions as the voltage detection means 18 in the present embodiment. The processing of the target current generation unit 110 is the same as that of the first embodiment except that the processing of the direct current component suppression unit 8 is different. Note that the DC voltage detection means 6 may be provided between the inductor 3 and the filter circuit 5, or may be provided between the current detection means 7 and the output terminals u1 and u2.

In the power conversion device of this embodiment, the voltage detection means is constituted of a capacitor C _d and resistor R _d from the circuit connected in series between the output terminals u1, u2, is applied between the output terminals u1, u2 DC DC voltage detection means 6 for detecting the voltage component V _D is included, and the target current generation means 110 is included in the single-phase AC power by correcting the target current j (t) based on the DC voltage component V _D. DC component suppressing means 8 for suppressing the DC component to be generated. Note that reference numeral 18 in FIG. 7 functions as a means for detecting the filter voltage v (t).

  If comprised in this way, the power converter which can suppress the direct current component contained in the alternating current power output from a power converter device without using big parts like a reactor, and can miniaturize a device with high-speed response and high accuracy Can provide.

Since during the DC component _{I D} generated on the DC component _{V D} and the target current j of the output terminal voltage v (t) (t) holds the relationship (Equation _6), the I D = _{V D} · alpha It can be seen that the DC component can be suppressed by feeding back the corresponding correction amount j _h (t) to the target current j (t). As the correction amount j _h (t), a constant value having a polarity opposite to that of the DC component _ID may be used, or a value calculated by (Equation 6) may be used.

FIG. 8 is a diagram illustrating an example of processing of the DC component suppressing unit 8 in the third embodiment. The DC component suppression means 8 is constituted by an analog circuit, and the DC component _ID is obtained. The DC component suppression unit 8 includes an amplifier 34 as an amplification unit that amplifies the DC component V _D detected by the DC voltage detection unit 6 and an _ID polarity determination circuit 39. In this embodiment, the DC component V _D is inputted to the amplifier 34 and amplified. The detected minute DC component V _D is amplified by the amplifier 34, the high frequency component is removed through the low-pass filter 35, input to the photocoupler 38, and the _ID polarity is output by the output signal of the photocoupler 38 insulated from the input unit. The determination circuit 39 is operated to determine the polarity of the DC component _ID of the load current. If a single-phase, if the voltage of the capacitor C _d is positively biased, the DC component I _D also positively biased, if the voltage of the capacitor C _d is negatively biased, the DC component I _D to the negative It will be biased. A correction amount j _h (t) is set in advance in the computing unit 40. When the polarity of the DC component _ID of the load current is positive, a correction amount with a negative sign is output and the polarity of I _aD is negative. In this case, the correction amount of the positive sign is output and input to the fifth adder 22. The low-pass filter 35 can be omitted. In this embodiment, without using a large component such as a reactor, the DC component included in the AC power output from the power converter can be easily suppressed by a simple circuit configuration using an analog circuit, and a high-speed response. It is possible to provide a power conversion device that can reduce the size of the device with high accuracy.

FIG. 9 shows a circuit configuration example of the three-phase power converter in the fourth embodiment. In FIG. 9, parts having the same functions as those in FIG. Differences compared to FIG. 3 will be mainly described. A DC voltage detecting means 6 is inserted between the filter circuit 5 and the second current detecting means 7, and the DC voltage detecting means 6 uses the DC component of the output terminal voltage v (t) (specifically, three lines). The DC component of two line voltages among the inter-voltages) V _abD , V _cbD is detected, and the DC component suppression means 8 is a DC voltage detection means instead of inputting the filter voltage detected by the filter circuit 5. The difference is that the direct current components V _abD and V _cbD of the output terminal voltage v (t) detected at 6 are input and the target current correction amount j _h (t) is calculated. DC voltage detection unit 6 is provided between the filter circuit 5 and the current detecting means 7, between lines ab, the resistors R _d and a capacitor C _d between cb connected in series, a resistor R _d and a capacitor C _d DC components V _abD and V _cbD included between the wiring ab and the wiring cb are detected from the intermediate point. In the present embodiment, the DC voltage detection means 6 functions as a voltage detection means. Further, () in FIG. 9 means that it can be omitted. Note that the DC voltage detection means 6 may be provided between the inductor 3 and the filter circuit 5, or may be provided between the current detection means 7 and the output terminals u, v, and w.

In the power conversion device according to the present embodiment, the voltage detection means is composed of a circuit in which a capacitor _Cd and a resistor _Rd are connected in series between the output terminals u, v, and w, and between the output terminals u, v, and w. DC voltage detection means 6 for detecting the applied DC voltage component V _D (V _abD , V _cbD ) is _provided , and the target current generation means 110 is based on the DC voltage component V _D (V _abD , V _cbD ), By correcting the target current j (t) (j _a (t), j _b (t), j _c (t)), the DC component suppressing means 8 is provided that suppresses the DC component included in the three-phase AC power. . Note that reference numeral 18 in FIG. 9 functions as a means for detecting the filter voltage v (t). Further, there may be three DC voltage detection means 6 and filter voltage detection means 18.

  With this configuration, even in three-phase AC, the DC component contained in AC power output from the power conversion device can be suppressed without using large components such as a reactor, and the device can be operated with high speed response and high accuracy. A power converter that can be miniaturized can be provided.

The processing of the target current generation means 110 is the same as that of the second embodiment except that the processing of the direct current component suppression means 8 is different.
(Expression 11a) and (Expression 11b) are derived from (Expression 7a) to (Expression 7c) and the following (Expression 10).

I _aD + I _bD + I _cD = 0 (Equation 10)
I _aD = α / 3 (2V _abD + V _cbD ) (Equation 11a)
I _cD = −α / 3 · (V _abD + 2V _cbD ) (Equation 11b)

From this, if the calculation results of (2V _abD + V _cbD ) and (V _abD + 2V _cbD ) are known, the direct current components I _aD , I _bD , and I _cD of the load current flowing through the wirings a, b, and c can be obtained. It can be seen that the DC component can be suppressed by feeding back the DC components I _aD , I _bD , and I _cD to the target current j (t).

FIG. 10 is a diagram illustrating an example of processing of the DC component suppressing unit 8 in the fourth embodiment. This is a flow in which the DC component suppression means 8 is configured by an analog circuit, and determines the DC components I _aD and I _cD of the load current i _s (t) according to (Equation 11a) and (Equation 11b). The direct current component suppression means 8 includes amplifiers 34a and 34b as amplification means for amplifying the two direct current components V _abD and V _cbD detected by the direct current voltage detection means 6, an addition circuit 37a as a first addition means, An adder circuit 37b as an adder, an _IaD polarity determiner 39a as a first determiner, and an _IcD polarity determiner 39b as a second determiner.

In the present embodiment, the first DC component V _abD and the second DC component V _cbD are input to the amplifiers 34a and 34b and amplified. A minute DC component V _abD detected between the wirings ab is amplified by an amplifier 34a, a high frequency component is removed through a low-pass filter 35a, and doubled by a doubler 36a to obtain 2V _abD . This is detected between the wirings cb, amplified by the amplifier 34b, removed from the high frequency component through the low pass filter 35b, and the obtained DC component V _cbD is added by the adder circuit 37a to obtain the calculation result (2V _abD + V _cbD ). obtain. The calculation result is input to the photocoupler 38a, and the _IaD polarity determination circuit 39a is operated by the output signal of the photocoupler 38a insulated from the input unit to determine the polarity of the direct current component _IaD of the load current. A correction amount j _h (t) is set in advance in the arithmetic unit 40, and when the polarity of the direct current component I _aD of the load current is positive, a negative correction amount is output, and when the polarity of I _aD is negative Outputs a positive correction amount and inputs it to the fifth adder 22. On the other hand, the DC component V _abD detected between the wirings ab and amplified by the amplifier 34a and obtained through the low-pass filter 35a, and detected between the wirings cb and amplified by the amplifier 34b and _passed through the low-pass filter 35b by the doubler 36b. The DC component 2V _cbD obtained by _multiplying is added by the adder circuit 37b to obtain a calculation result (V _abD + 2V _cbD ). As for the calculation result, the polarity of the DC component I _cD of the load current is determined by the I _cD polarity determination circuit 39b through the photocoupler 38b, and a positive or negative correction amount is input to the fifth adder 22 by the calculator 40. To do.

In the power conversion device according to the present embodiment, the DC component suppression unit 8 includes amplification _units 34 a and 34 b that amplify the two DC components V _abD and V _cbD detected by the DC voltage detection unit 6, First addition means 37a for adding twice the direct current component V _abD and the second direct current component V _cbD , and adding the first direct current component V _abD and the second direct current component V _cbD twice. The first adding means 37b, the first determining means 39a for determining the polarity of the voltage value added by the first adding means 37a, adding a sign based on the determination result, and the second adding means. A second determination unit 39b that determines the polarity of the voltage value added in 37b, adds a sign based on the determination result, and outputs the result.

  As described above, in this embodiment as well, in the same manner as in the third embodiment, the DC component is detected by correcting the target current by detecting the DC component from the voltage between the output terminals by a simple circuit configuration using an analog circuit. Can be suppressed.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made to the embodiments without departing from the spirit of the present invention. It is.

  For example, although the case where a load is directly connected to the output terminal of the power conversion device has been described in the above embodiment, the present invention can also be applied to the case where a transformer is present at the output terminal of the power conversion device. The primary voltage v (t) applied to the primary side of the transformer as the voltage between the output terminals is detected by the voltage detection means, and the target current j (t) is corrected by the direct current component suppression means 8, whereby the converter It is possible to suppress the direct current component that is output from the power source and included in the alternating current power and flows to the transformer, and to prevent the transformer from being magnetized.

In the above embodiment, the target current generating means for generating the target current is not limited to the configuration described in the embodiment, and various configurations are possible. For example, in the above embodiment, an example in which the load current detected by the second current detection unit is reflected in the target current has been described, but the second current detection unit can be omitted. Also, the filter current command i _CF and the deviation compensation command D (t) can be omitted. Further, the filter circuit may be composed of only the capacitor C _F except for the resistor R _F. Further, αβ conversion may be used instead of dq conversion, and coordinate conversion may not be performed. Further, the order of the dq converter 24 and the low-pass filter 25 may be changed, and the target current correction in the DC component suppression means 8 can be performed in the dq space. Further, the integrating means, the multiplying means, and other means may be constituted by individual circuits, or may be constituted by being integrated or divided in the same circuit. Further, the integration time and the gain value can be variously changed.

  The present invention is used in a power conversion device that generates AC power from a DC power supply to suppress a DC component contained in AC power output from a converter.

It is a figure which shows the circuit structural example of the single phase power converter device in 1st Embodiment. It is a figure which shows the example of a processing flow of the direct current | flow component suppression method of the power converter device in 1st Embodiment. It is a figure which shows the circuit structural example of the three-phase power converter device in 2nd Embodiment. It is a figure which shows the example of a process of the direct current | flow component suppression means in 2nd Embodiment. It is a figure which shows the experimental result at the time of adding a direct-current component to the target electric current in 2nd Embodiment. It is a figure which shows the example of the experiment result of the transient response in 2nd Embodiment. It is a figure which shows the circuit structural example of the single phase power converter device in 3rd Embodiment. It is a figure which shows the example of a process of the direct current | flow component suppression means in 3rd Embodiment. It is a figure which shows the circuit structural example of the three-phase power converter device in 4th Embodiment. It is a figure which shows the example of a process of the direct current | flow component suppression means in 4th Embodiment. It is a figure which shows the circuit structural example of the single phase power converter device which is not taking DC component suppression measures. It is a figure which shows the processing flow of the control method of the power conversion in the single phase power converter device which is not taking DC component suppression measures. It is a figure which shows the circuit structural example of the three-phase power converter device which is not taking DC component suppression measures. It is a figure which shows the experimental result at the time of adding a DC component to the target electric current of the three-phase power converter device which is not taking DC component suppression measures.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC power supply 2 Converter 3 Inductor 4 Load 5 Filter circuit 6 DC voltage detection means 7 Second current detection means 8 DC component suppression means 9 Second amplifier 10 Filter voltage command means 11 Filter current command means 12 PWM current deviation compensation Means 13 First amplifier 14 Third amplifier 15 Second adder 16 Fourth adder 17 PWM control means 18 Voltage detection means 19 First current detection means 20 First adder 21 Third adder 22 5th adder 23 6th adder 24 1st dq converter 25 Low pass filter 26 2nd dq converter 27 Inverse dq converter 31a, 31b Integration means 32a, 32b Multiplication means 33 Correction amount calculation means 34 , 34a, 34b Amplifiers 35, 35a, 35b Low pass filters 36a, 36b Doublers 37a, 37b Adder circuits 38, 38a, 38b Photocoupler 39 _{I D} polarity determination circuit 39a _{I aD} polarity determination circuit 39 b _{I cD} polarity determination circuit 40 calculator 100 main circuit 110 target current generation means 120 signal converting means a, a1, a2, b, c wiring _C F, _{C d} capacitor D (t) the DC component of the electromotive voltage _{I D} target current deviation compensation command _{E B} DC power source _i p (t) output current _i s (t) load current _{i CF} filter current command j (t) target current _j 1 (t ) Primary target current j _h (t) Target current correction amount L _P inductance L _F gain reciprocal R _F , R _d resistance s Laplace operator t Time u, u 1, u 2, v, w Output terminal v (t ) Output terminal voltage (filter voltage)
v _C (t) Filter voltage command V _D DC component of output voltage α, β, γ Amplification factor Δ (t) Error between output current and target current

Claims (12)

An error-following AC current control type single-phase power converter that generates single-phase AC power from a DC power source and supplies power to a load connected to an output terminal;
A converter for converting DC power from the DC power source into single-phase AC power;
An inductor connected to the AC side of the converter;
Current detection means for detecting an output current flowing through the inductor;
Voltage detecting means for detecting a voltage between the output terminals applied between the output terminals;
Target current generating means for generating a target current as a target value of the output current;
Converter control means for performing pulse width modulation control on the converter based on an error between the output current and the target current;
The target current generating means amplifies the integrated value of the voltage between the output terminals detected by the voltage detecting means and corrects the target current, thereby suppressing a DC component contained in the single-phase AC power. Having component suppression means;
Single phase power converter. A filter circuit connected between the output terminals for removing a switching frequency component included in the single-phase AC power;
The voltage detection means detects a filter voltage applied to the filter circuit as a voltage between the output terminals,
The direct current component suppression means amplifies an integral value of the filter voltage to correct the target current;
The single phase power converter device according to claim 1.   The current detection means is a first current detection means;
  Second current detection means for detecting a load current flowing from the output terminal to the load;
  The target current generating means generates a filter voltage command means for generating a filter voltage command to be a target value of the output terminal voltage, and a filter current command to be a target value of a filter current flowing through a capacitor constituting the filter circuit. Filter current command means, PWM current deviation compensation means for generating a deviation compensation command for compensating for deviation between the output current and the target current, and output detected by the filter voltage command and the voltage detection means A target current is generated by adding the correction amount obtained by the DC component suppressing means to the primary target current obtained by multiplying the difference between the voltages between the terminals, the filter current command and the deviation compensation command by a coefficient, respectively;
  Subtracting the output current detected by the first current detection means from the target current generated by the target current generation means, and supplying the subtraction to the converter control means;
  The single phase power converter device according to claim 1 or 2. An error-following AC current control type single-phase power converter that generates single-phase AC power from a DC power source and supplies power to a load connected to an output terminal;
A converter for converting DC power from the DC power source into single-phase AC power;
An inductor connected to the AC side of the single-phase converter;
Current detection means for detecting an output current flowing through the inductor;
Voltage detecting means for detecting a voltage between the output terminals applied between the output terminals;
Target current generating means for generating a target current as a target value of the output current;
Converter control means for performing pulse width modulation control on the converter based on an error between the output current and the target current;
The voltage detection means is composed of a circuit in which a capacitor and a resistor are connected in series between output terminals, and has a DC voltage detection means for detecting a DC voltage component applied between the output terminals,
The target current generating unit includes a DC component suppressing unit that corrects the target current based on the DC voltage component to suppress a DC component included in the single-phase AC power;
Single phase power converter.   The current detection means is a first current detection means;
  A second current detecting means for detecting a load current flowing from the output terminal to the load; and a filter circuit connected between the output terminals and for removing a switching frequency component included in the single-phase AC power;
  The target current generating means generates a filter voltage command means for generating a filter voltage command to be a target value of the output terminal voltage, and a filter current command to be a target value of a filter current flowing through a capacitor constituting the filter circuit. Filter current command means, PWM current deviation compensation means for generating a deviation compensation command for compensating for deviation between the output current and the target current, and output detected by the filter voltage command and the voltage detection means A target current is generated by adding the correction amount obtained by the DC component suppressing means to the primary target current obtained by multiplying the difference between the voltages between the terminals, the filter current command and the deviation compensation command by a coefficient, respectively;
  Subtracting the output current detected by the first current detection means from the target current generated by the target current generation means, and supplying the subtraction to the converter control means;
  The single phase power converter device according to claim 4. The direct current component suppression means is configured to amplify the direct current component detected by the direct current voltage detection means, to determine the polarity of the voltage value of the direct current component, and to determine and output a sign based on the determination result Means;
The single phase power converter device according to claim 4 or 5 . An error-following AC current control type three-phase power converter that generates three-phase AC power from a DC power source and supplies power to a load connected to an output terminal;
A converter that converts DC power from the DC power source into three-phase AC power;
An inductor connected to the AC side of the converter;
Current detection means for detecting an output current flowing through the inductor;
Voltage detecting means for detecting a voltage between the output terminals applied between the output terminals;
Target current generating means for generating a target current as a target value of the output current;
Converter control means for performing pulse width modulation control on the converter based on an error between the output current and the target current;
The target current generating means amplifies the integrated value of the voltage between the output terminals detected by the voltage detecting means and corrects the target current, thereby suppressing a DC component contained in the three-phase AC power. Having component suppression means;
Three-phase power converter. A filter circuit connected between the output terminals for removing a switching frequency component included in the three-phase AC power;
The voltage detection means detects a filter voltage applied between connection points of the filter circuit and each wiring as the output terminal voltage,
The direct current component suppression means amplifies an integral value of the filter voltage to correct the target current;
The three-phase power converter according to claim 7 .   The current detection means is a first current detection means;
  Second current detection means for detecting a load current flowing from the output terminal to the load;
  The target current generating means generates a filter voltage command means for generating a filter voltage command to be a target value of the output terminal voltage, and a filter current command to be a target value of a filter current flowing through a capacitor constituting the filter circuit. Filter current command means, PWM current deviation compensation means for generating a deviation compensation command for compensating for deviation between the output current and the target current, and output detected by the filter voltage command and the voltage detection means A target current is generated by adding the correction amount obtained by the DC component suppressing means to the primary target current obtained by multiplying the difference between the voltages between the terminals, the filter current command and the deviation compensation command by a coefficient, respectively;
  Subtracting the output current detected by the first current detection means from the target current generated by the target current generation means, and supplying the subtraction to the converter control means;
  The three-phase power converter device according to claim 7 or 8. An error-following AC current control type three-phase power converter that generates three-phase AC power from a DC power source and supplies power to a load connected to an output terminal;
A converter that converts DC power from the DC power source into three-phase AC power;
An inductor connected to the AC side of the converter;
Current detection means for detecting an output current flowing through the inductor;
Voltage detecting means for detecting a voltage between the output terminals applied between the output terminals;
Target current generating means for generating a target current as a target value of the output current;
Converter control means for performing pulse width modulation control on the converter based on an error between the output current and the target current;
The voltage detection means is composed of a circuit in which a capacitor and a resistor are connected in series between output terminals, and has a DC voltage detection means for detecting a DC voltage component applied between the output terminals,
The target current generating unit includes a DC component suppressing unit that corrects the target current based on the DC voltage component to suppress a DC component included in the three-phase AC power;
Three-phase power converter.   The current detection means is a first current detection means;
  A second current detecting means for detecting a load current flowing from the output terminal to the load; and a filter circuit connected between the output terminals for removing a switching frequency component included in the three-phase AC power;
  The target current generating means generates a filter voltage command means for generating a filter voltage command to be a target value of the output terminal voltage, and a filter current command to be a target value of a filter current flowing through a capacitor constituting the filter circuit. Filter current command means, PWM current deviation compensation means for generating a deviation compensation command for compensating for deviation between the output current and the target current, and output detected by the filter voltage command and the voltage detection means A target current is generated by adding the correction amount obtained by the DC component suppressing means to the primary target current obtained by multiplying the difference between the voltages between the terminals, the filter current command and the deviation compensation command by a coefficient, respectively;
  Subtracting the output current detected by the first current detection means from the target current generated by the target current generation means, and supplying the subtraction to the converter control means;
  The three-phase power converter according to claim 10. A three-phase power converter for generating three-phase AC power from a DC power source and supplying power to a load connected to an output terminal;
A converter that converts DC power from the DC power source into three-phase AC power;
An inductor connected to the AC side of the converter;
Current detection means for detecting an output current flowing through the inductor;
Voltage detecting means for detecting a voltage between the output terminals applied between the output terminals;
Target current generating means for generating a target current as a target value of the output current;
Converter control means for performing pulse width modulation control on the converter based on an error between the output current and the target current;
The voltage detection means is composed of a circuit in which a capacitor and a resistor are connected in series between output terminals, and has a DC voltage detection means for detecting a DC voltage component applied between the output terminals,
The target current generating unit includes a DC component suppressing unit that corrects the target current based on the DC voltage component to suppress a DC component included in the three-phase AC power;
The direct current component suppression means includes an amplification means for amplifying two direct current components detected by the direct current voltage detection means, and a first addition means for adding twice the first direct current component and the second direct current component. A second adding means for adding the first DC component and twice the second DC component, and the polarity of the voltage value added by the first adding means. First determination means for adding a sign based on the output, and second determination for determining the polarity of the voltage value added by the second addition means and adding the sign based on the determination result Having means;
Three-phase power converter.

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