JP5922869B2 - Power converter - Google Patents

Description

  The present invention relates to a power converter for generating AC power of a desired frequency from an AC power supply, and particularly relates to measures for reducing power supply harmonics of the power converter.

  In the power conversion device, as a countermeasure against power harmonics, there is a case where control is performed so that the input current from the AC power supply side approaches a sine wave. For example, in the power conversion device disclosed in Patent Document 1, the feedback control unit (compensation current command generation unit) is constant to a value obtained by subtracting the absolute value of the measured value of the input current from the absolute value of the command value of the input current. A compensation current command value multiplied by a gain is generated. Then, a load such as a motor is controlled based on the compensation current command value, thereby suppressing the harmonic component of the input current. Here, the harmonic component is a frequency component that is an integral multiple of the fundamental wave component. In general, a harmonic component having a frequency n times that of the fundamental wave is referred to as an nth-order harmonic component.

JP 2005-130675 A

  By the way, the compensation current command generation unit generates a compensation current command value by multiplying a harmonic component of all orders in the input current by a constant gain. May not be sufficiently suppressed.

  This invention is made | formed in view of this point, The objective is to suppress reliably the harmonic component to suppress in the input current from the alternating current power supply side.

The first invention is directed to a power converter, has a plurality of switching elements (Sr, Ss, St, Su, Sv, Sw, Sx, Sy, Sz), and receives power from the AC power source (6) side. Conversion that converts the AC power to a load (7) by converting the AC power to a predetermined frequency by the switching operation of the plurality of switching elements (Sr, Ss, St, Su, Sv, Sw, Sx, Sy, Sz) Part (4) and harmonic components (Iin2, Iin3, Iin2, Iin3, ...) of the harmonic components (Iin2, Iin3, Iin4, ...) included in the input current (Iin) from the AC power source (6) side Iin4, ...) and to individually suppress includes the plurality of switching elements (Sr, Ss, St, Su , Sv, Sw, Sx, Sy, control unit for controlling the Sz) and (10), the control The unit (10) receives a current command generation unit (20) for generating a motor current command value for controlling the conversion unit (4), and the motor current command value, and based on the motor current command value The switch of the converter (4) A switching control unit (12) for controlling the chucking elements (Sr, Ss, St, Su, Sv, Sw, Sx, Sy, Sz), and a desired order harmonic component (Iin2, Iin3) in the input current (Iin) , Iin4,...) Corresponding to specific order correction values (Iin2 *, Iin3 *, Iin4 *,...), And the switching control based on the specific order correction values (Iin2 *, Iin3 *, Iin4 *,. A specific order correction unit (30) for correcting a motor current command value before being input to the unit (12) .

  In 1st invention, in the conversion part (4), the electric power from AC power supply (6) side is by switching operation of a plurality of switching elements (Sr, Ss, St, Su, Sv, Sw, Sx, Sy, Sz) It is converted into AC power having a predetermined frequency. The AC power converted in this way is output to the load (7).

In the first invention, the control unit (10) has a specific order harmonic component (Iin2) among the harmonic components (Iin2, Iin3, Iin4,...) Included in the input current flowing from the AC power supply (6) side. , Iin3, Iin4,...) Are individually controlled to control a plurality of switching elements (Sr, Ss, St, Su, Sv, Sw, Sx, Sy, Sz). Thereby, among the harmonic components (Iin2, Iin3, Iin4,...) Included in the input current (Iin), each of the harmonic components (Iin2, Iin3, Iin4,. Can be suppressed .

In the first invention , the motor command value for controlling the converter (4) is generated by the current command generator (20). On the other hand, in the specific order correction unit (30), specific order correction values (Iin2 *, Iin3 *, Iin4 *, corresponding to the desired harmonic components (Iin2, Iin3, Iin4, ...) to be suppressed in the input current (Iin) ...) is generated. The motor current command value is corrected by the specific order correction values (Iin2 *, Iin3 *, Iin4 *,...) And then input to the switching control unit (12). The conversion unit (4) is controlled by the switching control unit (12) based on the value corrected as described above.

In a second aspect based on the first aspect, the current command generation unit (20) includes a compensation current command generation unit (22) that generates a compensation current command value as the current command value. The generation unit (22) includes an input current command generation unit (22a) that generates a command value (Iin *) of the input current (Iin), and a command value (Iin generated by the input current command generation unit (22a)) The compensation current command value is generated by multiplying the absolute value (| Iin |) of the input current (Iin) subtracted from the absolute value (| Iin * |) of *) by a predetermined gain (K1) And an amplifying part (22c).

In the second invention , the switching control unit (12) controls the conversion unit (4) based on the compensation current command value as the current command value. This compensation current command value is obtained by subtracting the absolute value (| Iin |) of the input current from the absolute value (| Iin * |) of the command value of the input current in the input current command generator (22a). Generated by multiplying (K1). The compensation current command value generated in this way includes a harmonic component to be suppressed in the input current (Iin). By controlling the converter (4) based on the compensation current command value, the harmonic components (Iin2, Iin3, Iin4,...) That are desired to be suppressed in the input current (Iin) are suppressed.

  However, as described above, the compensation current command value is obtained by multiplying the difference between the input current command value (Iin *) and the current (Iin) by a predetermined gain (K1). Cannot be individually suppressed.

On the other hand, in the second invention , the specific order correction values (Iin5 *, Iin7 *, Iin9 *) corresponding to the harmonic components (Iin5, Iin7, Iin9) that cannot be sufficiently suppressed only by the compensation current command value. ) Can be generated. Then, the compensation current command value is corrected by the specific order correction value (Iin5 *, Iin7 *, Iin9 *), and the conversion unit (4) can be controlled based on the corrected value. As a result, all harmonic components (Iin2, Iin3, Iin4,...) That are desired to be suppressed in the input current (Iin) can be sufficiently suppressed.

According to a third invention, in the first or second invention , the specific order correction unit (30) extracts a harmonic component (Iin2, Iin3, Iin4,...) Of a desired order in the input current (Iin). Multiplying the harmonic component (Iin2, Iin3, Iin4,...) Extracted by the harmonic calculation unit (31) and the harmonic calculation unit (31) by a predetermined gain (K2_1, K2_2, K2_3,...) And a specific order amplification unit (32) for generating the specific order correction values (Iin2 *, Iin3 *, Iin4 *,...).

In the third invention , the harmonic calculation unit (31) extracts harmonic components (Iin2, Iin3, Iin4,...) Of a desired order in the input current (Iin). Then, the specific order amplification unit (32) multiplies the harmonic components (Iin2, Iin3, Iin4,...) By a predetermined gain (K2_1, K2_2, K2_3,. *, Iin3 *, Iin4 *, ...) is generated.

According to a fourth aspect, in the third aspect, the harmonic calculation unit (31) extracts the harmonic components (Iin2, Iin3, Iin4,...) By Fourier transform.

In the fourth invention , the harmonic components (Iin2, Iin3, Iin4,...) Are reliably extracted by Fourier transform.

According to a fifth invention, in any one of the first to fourth inventions , the converter circuit (2) for rectifying the voltage from the AC power supply (6) and the output of the converter circuit (2) are connected in parallel. A DC link unit (3) having a capacitor (3a) connected to the DC link unit (3), and the converter unit that converts an output voltage from the DC link unit (3) into an AC voltage and outputs the AC voltage to a load (7) The capacitance value of the capacitor (3a) is set to such a value that the input voltage of the converter (4) pulsates.

In the fifth invention , the voltage rectified by the converter circuit (2) is applied to the inverter circuit (4) via the DC link unit (3). The voltage applied to the inverter circuit (4) is converted into an AC voltage by the control unit (10) and then output to the load (7).

In the fifth invention , the capacitance value of the capacitor (3a) of the DC link part (3) is set to such a value that the input voltage of the inverter circuit (4) pulsates, so that the input current (Iin) is It becomes relatively easy to pulsate. That is, many harmonic components (Iin2, Iin3, Iin4,...) Are included in the input current (Iin). By using the first to fourth inventions for such a power converter, the harmonic components (Iin2, Iin3, Iin4,...) Of the input current (Iin) can be effectively suppressed.

  According to the first invention, of the harmonic components (Iin2, Iin3, Iin4,...) Included in the input current (Iin) from the AC power source (6) side, Since harmonic components can be suppressed by a necessary amount corresponding to each of Iin2, Iin3, Iin4,..., Harmonic components (Iin2, Iin3, Iin4,...) Of orders to be suppressed can be reliably suppressed.

Further, according to the first invention , the specific order correction values (Iin2 *, Iin3 *, Iin4 *,...) Generated corresponding to the harmonic components (Iin2, Iin3, Iin4,. The motor current command value before being input to the switching control unit (12) is corrected. Thereby, the harmonic components (Iin2, Iin3, Iin4,...) To be suppressed in the input current (Iin) can be reliably suppressed.

According to the second aspect of the invention , the harmonic components (Iin5, Iin7, Iin9) that cannot be suppressed even when the compensation current command value is used are identified corresponding to the harmonic components (Iin5, Iin7, Iin9). Order correction values (Iin5 *, Iin7 *, Iin9 *) can be generated.

For example, if the harmonic component is to be suppressed only by the specific order correction unit (30) without using the compensation current command generation unit (22), the specific order correction values (Iin2 *, Iin3 *, Iin4 *, ...) need to be generated. On the other hand, in the second invention , the harmonic components (Iin5, Iin7, Iin9) that cannot be suppressed only by the compensation current command value (Idq2 *) generated by the compensation current command generation unit (22). Only the specific order correction values (Iin5 *, Iin7 *, Iin9 *) corresponding to the components (Iin5, Iin7, Iin9) need be generated. Therefore, the number of specific order correction values that need to be generated can be reduced as compared with the case where only the specific order correction unit (30) suppresses all harmonic components. Therefore, the processing speed in the specific order correction unit (30) can be increased accordingly.

Further, according to the third invention , the harmonic component (Iin2, Iin3, Iin4,...) Extracted by the harmonic calculation unit (31) is analyzed by the specific order amplification unit (32). By multiplying gains corresponding to (Iin2, Iin3, Iin4,...), Specific order correction values (Iin2 *, Iin3 *, Iin4 *,...) Can be generated.

According to the fourth aspect of the invention , the harmonic components (Iin2, Iin3, Iin4,...) Can be reliably extracted by Fourier transform.

Further, according to the fifth aspect of the invention , in the input current (Iin) from the AC power source (6) side in which the harmonic components (Iin2, Iin3, Iin4,. Iin3, Iin4, ...) can be effectively suppressed.

FIG. 1 is a block diagram illustrating a configuration of a power conversion apparatus according to Embodiment 1 of the present invention. FIG. 2 is a block diagram illustrating a configuration of the control unit. FIG. 3 is a block diagram illustrating a configuration of the specific order control unit. FIG. 4 is a block diagram illustrating a configuration of a control unit of the power conversion apparatus according to the second embodiment of the present invention. FIG. 5 is a block diagram illustrating a configuration of the specific order control unit according to the second embodiment of the present invention. FIG. 6 is a block diagram illustrating a configuration of the power conversion device according to the first modification. FIG. 7 is a block diagram illustrating a configuration of a power conversion device according to the second modification. FIG. 8 is a block diagram illustrating a configuration of the power conversion device according to the third modification.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use.

Embodiment 1 of the Invention
-Overall configuration-
As shown in FIG. 1, a power converter (1) according to Embodiment 1 of the invention includes a converter circuit (2), a DC link unit (3), an inverter circuit (4), a current detection unit (5), and a control unit. (10) is provided. This power converter (1) converts AC power supplied from a single-phase AC power supply (6) into power of a predetermined frequency and supplies it to a motor (7) as a load. . In addition, the motor (7) of this Embodiment 1 is a three-phase alternating current motor, and is for driving the compressor provided in the refrigerant circuit of the air conditioner.

  The converter circuit (2) is connected to the AC power supply (6), and full-wave rectifies the AC output from the AC power supply (6) into DC. In this example, the converter circuit (2) is a diode bridge circuit in which a plurality (four in the present embodiment) of diodes (D1 to D4) are connected in a bridge shape. These diodes (D1 to D4) perform full-wave rectification of the AC voltage of the AC power source (6).

  The DC link part (3) includes a capacitor (3a). The capacitor (3a) is connected in parallel to the output of the converter circuit (2), and the DC voltage (DC link voltage (Vdc)) generated across the capacitor (3a) is connected to the input node of the inverter circuit (4). ing. The capacitor (3a) is constituted by, for example, a film capacitor. This capacitor (3a) only generates ripple voltage (voltage fluctuation) that corresponds to the switching frequency when the switching elements (Su, Sv, Sw, Sx, Sy, Sz) of the inverter circuit (4) perform switching operation. It has a capacitance that can be smoothed. That is, the capacitor (3a) is a small-capacitance capacitor that does not have a capacitance that smoothes the voltage rectified by the converter circuit (2) (voltage fluctuation caused by the power supply voltage). For this reason, the DC link voltage (Vdc) output from the DC link unit (3) has a large pulsation such that the maximum value is twice or more the minimum value.

  The inverter circuit (4) has an input node connected in parallel to the capacitor (3a) of the DC link section (3), and switches the output of the DC link section (3) to convert it to three-phase AC, and is connected to the motor (7) to supply. The inverter circuit (4) of Embodiment 1 is configured by a plurality of switching elements (Su, Sv, Sw, Sx, Sy, Sz) being bridge-connected. Since this inverter circuit (4) outputs three-phase alternating current to the motor (7), it has six switching elements (Su, Sv, Sw, Sx, Sy, Sz). Specifically, the inverter circuit (4) includes three switching legs formed by connecting two switching elements in series with each other, and in each switching leg, an upper arm switching element (Su, Sv, Sw) and a lower arm switching element. The midpoints of (Sx, Sy, Sz) are connected to coils (not shown) of the respective phases of the motor (7). In addition, free-wheeling diodes (Du, Dv, Dw, Dx, Dy, Dz) are connected in antiparallel to each switching element (Su, Sv, Sw, Sx, Sy, Sz). The inverter circuit (4) switches the DC link voltage (vdc) input from the DC link unit (3) by turning on and off these switching elements (Su, Sv, Sw, Sx, Sy, Sz). Convert to phase AC voltage and supply to motor (7). The on / off operation is controlled by the control unit (10).

  The current detection unit (5) is for detecting the input current (Iin) flowing from the converter circuit (2) to the DC link unit (3). The current detection unit (5) is connected to the input side of the DC link unit (3). The current detector (5) may be connected to the input side of the converter circuit (2) so as to detect an input current flowing from the AC power supply (6) to the converter circuit (2).

  The control unit (10) controls switching (on / off operation) in the inverter circuit (4) so that the current (motor current) flowing through the motor (7) pulsates in synchronization with the pulsation of the power supply voltage (Vin). . That is, the power converter (1) is an example of a so-called capacitorless inverter. As shown in FIG. 2, the control unit (10) includes a power supply phase calculation unit (11), a current command generation unit (20), a specific order correction unit (30), and a switching control unit (12).

  The power supply phase calculation unit (11) is for calculating the phase (θin) of the AC power supply (6). The calculated phase (θin) of the AC power supply (6) is output to the current command generation unit (20) and the specific order correction unit (30).

  The current command generator (20) includes a main command generator (21) and a compensation current command generator (22).

  The main command generation unit (21) includes a speed control unit (21a), a torque command modulation unit (21b), and a secondary harmonic application unit (21c).

  A deviation between the rotational angular frequency (ω) of the mechanical angle of the motor (7) and the command value (ω *) of the mechanical angle is input to the speed control unit (21a). The speed control unit (21a) performs a proportional / integral calculation (PI calculation) on the deviation to generate a torque command value (T *), and sends the torque command value (T *) to the torque command modulation unit (21b). Output.

  The torque command modulation unit (21b) receives the phase (θin) of the AC power supply (6) as an input, generates a sine value (sin (θin)), and multiplies the torque command by a modulation coefficient corresponding thereto. The modulation coefficient is, for example, | sin (θin) | or sin2 (θin). In order to suppress power supply harmonics and motor output current peaks, the modulation coefficient can be changed according to the power supply frequency. Further, the modulation coefficient may be determined according to a sine value (sin (θin + Δ)) obtained by shifting the phase (θin) of the AC power supply (6) by Δ so that the output current of the motor becomes a sine wave. As a result, the same effect as that obtained by applying a frequency component twice the power supply frequency, which will be described later, can be obtained.

  The secondary harmonic application unit (21c) applies a frequency component twice the power supply frequency to the output value of the torque command modulation unit (21b) so that the output power from the motor (7) is sinusoidal. The main current command value (Idq1 *) is generated.

  The compensation current command generation unit (22) includes an input current command generation unit (22a), a subtracter (22b), and an amplification unit (22c). The compensation current command generation unit (22) is for generating a compensation current command value for suppressing the harmonic component of the input current (Iin).

  The input current command generator (22a) performs a Fourier transform on the input current (Iin) detected by the current detector (5) to extract a fundamental wave component, and multiplies it by sin (θin) to calculate the input current Command value (Iin *) is generated.

  The subtracter (22b) is the input detected by the current detector (5) from the absolute value (| Iin * |) of the command value (Iin *) of the input current generated by the input current command generator (22a). The absolute value (| Iin |) of the current is subtracted and output to the amplifying unit (23).

  The amplifying unit (22c) multiplies the output value of the subtracter (22b) by a predetermined gain (K1) to generate a compensation current command value (Idq2 *).

  The compensation current command value (Idq2 *) generated by the compensation current command generation unit (22) is a specific order correction value (Iin5 *, Iin7 *, Iin9) generated by a specific order correction unit (30) described in detail later. After being subtracted by *), it is added to the main current command value (Idq1 *) by the adder (17). That is, the current command value (Idq *) input to the switching control unit (12) is calculated by the specific order correction value (Iin5 *, Iin7 *, Iin9 *) before being input to the switching control unit (12). After being subtracted, it is input to the switching control unit (12).

  The switching control unit (12) includes a subtracter (12a), a current control unit (12b), and a PWM calculation unit (12c).

  The subtracter (12a) receives the value obtained by subtracting the specific order correction value (Iin5 *, Iin7 *, Iin9 *) from the motor current command value (Idq *) before being input to the subtractor (12a). The The subtractor (12a) outputs a value obtained by subtracting the motor current (Idq) from this value to the current control unit (12b).

  The current control unit (12b) generates a voltage command value (Vdq *) based on the output value of the subtracter (12a). The voltage command value (Vdq *) is output to the PWM calculation unit (12c).

  The PWM calculation unit (12c) generates a gate signal (G) for controlling the on / off operation of each switching element (Su, Sv, Sw, Sx, Sy, Sz) based on the voltage command value (Vdq *) or the like. .

-Specific order correction unit-
As shown in FIGS. 2 and 3, the specific order correction unit (30) includes a harmonic calculation unit (31), a specific order amplification unit (32), and a subtracter (33). This specific order correction unit (30) suppresses the harmonic component of the input current (Iin) that cannot be suppressed only by the compensation current command value (Idq2 *) generated by the compensation current command generation unit (22). belongs to.

  The harmonic calculation unit (31) performs a Fourier transform on the input current (Iin) detected by the current detection unit (5) to extract a desired harmonic component. In this way, the harmonic component can be reliably extracted by using the Fourier transform. In the first embodiment, the harmonic calculation unit (31) extracts the fifth harmonic component (Iin5), the seventh harmonic component (Iin7), and the ninth harmonic component (Iin9) of the input current (Iin). Yes. In addition, although the harmonic calculating part (31) in this Embodiment 1 is extracting the 5th, 7th, 9th harmonic component, it is not restricted to this, In the harmonic calculating part (31), input current (Iin ) Can be extracted.

  As shown in FIG. 3, the specific order amplification unit (32) includes amplification units (32a, 32b) corresponding to the harmonic components (Iin5, Iin7, Iin9) extracted by the harmonic calculation unit (31). 32c). These amplifying units (32a, 32b, 32c) use gains (K2_5, K2_7, K2_9) corresponding to the respective harmonic components (Iin5, Iin7, Iin9) as the respective harmonic components (Iin5, Iin7, Iin9). Is multiplied by to generate specific order correction values (Iin5 *, Iin7 *, Iin9 *). Specifically, the specific order amplification unit (32) includes a fifth-order harmonic component amplification unit (32a), a seventh-order harmonic component amplification unit (32b), and a ninth-order harmonic component amplification unit (32c). . The fifth-order harmonic component amplifier (32a) multiplies the fifth-order harmonic component (Iin5) by the gain (K2_5) to generate a fifth-order harmonic component correction value (Iin5 *). The seventh harmonic component amplifier (32b) multiplies the seventh harmonic component (Iin7) by the gain (K2_7) to generate a seventh harmonic component correction value (Iin7 *). The ninth-order harmonic component amplification unit (32c) multiplies the ninth-order harmonic component (Iin9) by a gain (K2_9) to generate a ninth-order harmonic component correction value (Iin9 *).

  The subtracter (33) subtracts the specific order correction value (Iin5 *, Iin7 *, Iin9 *) from the compensation current command value (Idq2 *) generated by the compensation current command generation unit (22). This value is output to the adder (17).

-Operation of power converter-
In the first embodiment, since the small-capacitance capacitor (3a) is provided in the DC link section (3), the DC link voltage (Vdc) pulsates more greatly. Due to the pulsation of the DC link voltage (Vdc), the current conduction width of the diodes (D1 to D4) of the converter circuit (2) is widened, and as a result, the power factor is improved. The control unit (10) controls switching in the inverter circuit (4) so that the motor current pulsates in synchronization with the pulsation of the power supply voltage.

  In the first embodiment, the control unit (10) adds the main current command value (Idq1 *) and the compensation current command value (Idq2 *) to the motor current command value (Idq *) that is generated. Based on this, the inverter circuit (4) is controlled. Thereby, the harmonic component of the input current (Iin) can be suppressed.

  However, the compensation current command generator (22) generates a compensation current command value (Idq2 *) by multiplying all the harmonic components to be suppressed by a constant gain (K1). The harmonic component of may not be sufficiently suppressed.

  On the other hand, in the first embodiment, the switching control unit (12) determines the specific order correction value (Iin5 *, Iin7 *, from the current command value (Idq *) before being input to the switching control unit (12). The inverter circuit (4) is controlled based on the value obtained by subtracting Iin9 *). Thereby, the harmonic component of the order that cannot be suppressed only by the compensation current command value (Idq2 *) can be suppressed by using the specific order correction value (Iin5 *, Iin7 *, Iin9 *).

  In the first embodiment, the compensation current command generation unit (22) and the specific order correction unit (30) are used in combination in order to suppress a harmonic component of a desired order in the input current (Iin). In this way, for example, the number of specific order correction values that need to be generated can be reduced as compared with a case where all harmonic components that are to be suppressed only by the specific order correction unit (30) are suppressed. Then, since the number of specific order amplifying units can be reduced, the configuration of the specific order correcting unit (30) can be simplified, and as a result, the processing speed in the specific order correcting unit (30) can be increased.

-Effect of Embodiment 1-
As described above, in the power conversion device according to the first embodiment, in order to suppress the harmonic component of the input current (Iin), the compensation current command generation unit (22) and the specific order correction unit (30) are used in combination. doing. Thereby, the harmonic component that cannot be suppressed only by the compensation current command value (Idq2 *) generated by the compensation current command generation unit (22) can be suppressed by the specific order correction unit (30). Therefore, it is possible to reliably suppress all harmonic components that are desired to be suppressed in the input current (Iin). Further, by using the compensation current command generation unit (22) and the specific order correction unit (30) in combination as described above, the number of specific order correction values that need to be generated can be reduced. As a result, the configuration of the specific order correction unit (30) can be simplified, and further, the processing speed in the specific order correction unit (30) can be increased.

<< Embodiment 2 of the Invention >>
As illustrated in FIG. 4, the power conversion device (1) according to the second embodiment has a configuration in which the compensation current command generation unit (22) is omitted compared to the power conversion device according to the first embodiment. Further, as shown in FIG. 5, in the second embodiment, the specific order correction unit (30) performs specific order amplification corresponding to all harmonic components (Iin2 *, Iin3 *, Iin4 *,...) To be suppressed. (32a, 32b, 32c,...) Are provided. Specifically, the specific order correction unit (30) according to the second embodiment uses these harmonic components so that harmonic components (Iin2, Iin3, Iin4,...) From the second order to the 40th order can be suppressed. Specific order amplification units (32a, 32b, 32c,...) Corresponding to each of (Iin2, Iin3, Iin4,...) Are provided. Note that the specific order amplifying unit does not need to correspond to all of the second to 40th harmonic components, and may correspond to the harmonic component to be suppressed. In FIG. 5, only the second-order harmonic component amplification unit (32a), the third-order harmonic component amplification unit (32b), and the fourth-order harmonic component amplification unit (32c) among the specific order amplification unit (32). The specific order amplifying units of the subsequent orders are not shown.

-Effect of Embodiment 2-
Even if the compensation current command generation unit (22) is omitted as in the second embodiment, the specific order amplification units (32a, 32b, 32c,...) Are associated with the harmonic components to be suppressed in the input current (Iin). ) Can reliably suppress harmonic components to be suppressed in the input current (Iin).

-Other embodiments-
In each of the above embodiments, a so-called capacitor-less inverter is targeted. However, the present invention is not limited to this, and a power conversion device using an electrolytic capacitor having a relatively large capacity as a capacitor can also be targeted.

  In each of the above embodiments, the single-phase AC power source (6) is used as the power source. However, the present invention is not limited to this, and a three-phase AC power source is used as in the example shown in FIG. 6 (Modification 1). You can also The converter circuit (2) shown in FIG. 6 is a diode bridge circuit in which six diodes (D1 to D6) are connected in a bridge shape.

  Further, each of the above embodiments is directed to a power conversion device including the converter circuit (2) and the inverter circuit (4). However, the present invention is not limited to this. For example, the example shown in FIG. A matrix converter (4) such as the example shown (Modification 3) can also be targeted. These matrix converters (4) constitute a conversion unit that converts electric power from the AC power supply (6) into AC power having a predetermined frequency. Transistors or the like can be used for the switching elements (Sr, Ss, St, Su, Sv, Sw, Sx, Sy, Sz) of the matrix converter (4).

  Moreover, in each said embodiment, the electric current command value (Idq *) before being input into a switching control part (12) is subtracted by specific order correction value (Iin2 *, Iin3 *, Iin4 *, ...). However, not limited to this, the mechanical angle command value (ω *) and voltage command value (Vdq *) of the motor (7) are subtracted by specific order correction values (Iin2 *, Iin3 *, Iin4 *, ...). May be.

  As described above, the present invention is particularly useful in a so-called capacitorless inverter.

2 Converter circuit 3 DC link part 3a Capacitor 4 Inverter circuit, matrix converter (conversion part)
6 AC power supply 7 Motor (load)
DESCRIPTION OF SYMBOLS 10 Control part 12 Switching control part 20 Current command generation part 22 Compensation current command generation part 22a Input current command generation part 22c Amplification part 30 Specific order correction part 31 Harmonic calculation part 32a, 32b, 32c Specific order amplification part Idq * Motor current Command value (current command value)
Idq1 * Main current command value (current command value)
Idq2 * Compensation current command value (current command value)
Iin Input current Iin * Input current command value Iin2, Iin3, Iin4 Harmonic component Iin2 *, Iin3 *, Iin4 * Specific order correction value K1 Gain K2_1, K2_2, K2_3 Gain Sr, Ss, St, Su, Sv, Sw, Sx, Sy, Sz Switching element

Claims (5)

It has a plurality of switching elements (Sr, Ss, St, Su, Sv, Sw, Sx, Sy, Sz), and the electric power from the AC power source (6) side is used as the plurality of switching elements (Sr, Ss, St, Su , Sv, Sw, Sx, Sy, Sz) is converted into AC power of a predetermined frequency by the switching operation, and the converter (4) that outputs the AC power to the load (7),
Individual harmonic components (Iin2, Iin3, Iin4, ...) of the harmonic components (Iin2, Iin3, Iin4, ...) included in the input current (Iin) from the AC power supply (6) side A control unit (10) for controlling the plurality of switching elements (Sr, Ss, St, Su, Sv, Sw, Sx, Sy, Sz)
The control unit (10)
A current command generator (20) for generating a motor current command value for controlling the converter (4);
The motor current command value is input, the switching elements of the converter section on the basis of the motor current command value (4) (Sr, Ss, St, Su, Sv, Sw, Sx, Sy, Sz) switching control for controlling the Part (12),
A specific order correction value (Iin2 *, Iin3 *, Iin4 *,...) Corresponding to a harmonic component (Iin2, Iin3, Iin4,...) Of a desired order in the input current (Iin) is generated and the specific order A specific order correction unit (30) for correcting a motor current command value before being input to the switching control unit (12) by correction values (Iin2 *, Iin3 *, Iin4 *,...) Power converter. In claim 1 ,
The current command generator (20) includes a compensation current command generator (22) that generates a compensation current command value as the current command value,
The compensation current command generator (22)
An input current command generator (22a) that generates a command value (Iin *) of the input current (Iin);
The value obtained by subtracting the absolute value (| Iin |) of the input current (Iin) from the absolute value (| Iin * |) of the command value (Iin *) generated by the input current command generation unit (22a) An amplifying unit (22c) that generates the compensation current command value by multiplying by a gain (K1). In claim 1 or 2 ,
The specific order correction unit (30)
A harmonic calculation unit (31) for extracting harmonic components (Iin2, Iin3, Iin4,...) Of a desired order in the input current (Iin);
The specific order correction value (Iin2 *) is obtained by multiplying the harmonic components (Iin2, Iin3, Iin4,...) Extracted by the harmonic calculation unit (31) by a predetermined gain (K2_1, K2_2, K2_3,...). , Iin3 *, Iin4 *,...), And a specific order amplifying unit (32). In claim 3 ,
The harmonic calculation unit (31) extracts the harmonic components (Iin2, Iin3, Iin4,...) By Fourier transform. In any one of claims 1 to 4 ,
A converter circuit (2) for rectifying the voltage from the AC power supply (6);
A DC link part (3) having a capacitor (3a) connected in parallel to the output of the converter circuit (2);
The inverter circuit (4) as the conversion unit that converts the output voltage from the DC link unit (3) into an AC voltage and outputs the AC voltage to the load (7),
The capacity value of the capacitor (3a) is set to such a value that the input voltage of the inverter circuit (4) pulsates.

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