JP2005057938A - Power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a small-sized power converter wherein the total number of elements for use in the converter is reduced. <P>SOLUTION: The voltage of a storage battery or a capacitor 2 is used for the voltage of one phase among three phases as almost the half voltage of a DC power supply 1, and an inverter control means 12 that controls voltages of two phases among the three phases of an output so as to be outputted on the basis of the potential of the storage battery of the capacitor 2. As a result, since the potential of the storage battery or the capacitor 2 can be utilized as it is as the voltage of one terminal of a motor 7, two pieces of semiconductor switch elements that correspond to one phase can be dispensed with, thus enabling the three-phase motor 7 to be driven by four pieces of the semiconductor switch elements 8 to 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power conversion device including semiconductor switch elements. In particular, the present invention relates to a power conversion device including a plurality of power conversion circuits connected to a DC power source.

An apparatus using a solar cell or a fuel cell as a power source includes a plurality of power conversion circuits and auxiliary devices such as a battery charger for power storage and an inverter for driving a cooling fan. For example, in a drive device for a fuel cell vehicle, in addition to a motor and an inverter for driving the vehicle, a battery for storage and a DC / DC converter, a pump and inverter for hydrogen circulation, a pump and inverter for cooling water, a fuel cell An air compressor and an inverter for supplying air are used (for example, see Non-Patent Document 1).
These power conversion circuits represented by DC / DC converters and inverters are composed of a plurality of semiconductor switch elements. For example, a conventional inverter uses two semiconductor switch elements connected in series between the positive and negative terminals of a DC power source per output phase. In the case of a normal three-phase inverter, a total of six semiconductor switches An element was required. Therefore, a total of 24 semiconductor switch elements are used even with only the four inverters used in the driving apparatus of the fuel cell vehicle.

"Development of Fuel-Cell Hybrid Vehicle" (Tadaichi Matsumoto, Nobuo Watanabe, Hiroshi Sugiura and Tetsuhiro Ishikawa SAE 2002

  As described above, in the conventional power conversion device, the three-phase inverter requires six semiconductor switch elements, so that the total number of semiconductor switch elements is large particularly in a device that requires a plurality of inverters. was there. Further, in connection with this problem, since a large number of semiconductor switch elements are used, there is a problem that the apparatus becomes large.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to reduce the total number of elements used and to obtain a small-sized power conversion device.

  A power conversion device according to the present invention is a DC / DC converter that is connected to a DC power source and a power storage unit having one terminal connected to the DC power source, and charges and discharges the power storage unit with a voltage of the DC power source, and A power conversion device including an inverter that drives a load with a voltage of the DC power supply, the power conversion device including a plurality of semiconductor switch elements and a control unit that generates a control signal for the semiconductor switch element, wherein the voltage of the power storage unit is The voltage of the DC power supply is approximately ½ of the voltage, and one terminal of the load is connected to the other terminal of the power storage unit, and the voltage of the other terminal of the load is based on the voltage of the power storage unit. The control signal is generated so as to be controlled.

  In addition, a DC power supply and one terminal connected to the power storage means connected to the DC power supply, a DC / DC converter that charges and discharges the power storage means with a voltage of the DC power supply, a plurality of semiconductor switch elements, and the A power conversion device comprising a three-level inverter configured to drive a load with a voltage of the DC power supply, wherein the voltage of the power storage means is a voltage of the DC power supply. The control signal so as to control the voltage of the load to a desired voltage by connecting the other terminal of the power storage means to the neutral point voltage terminal of the three-level inverter. Is generated.

  In addition, a DC power supply and one terminal connected to the power storage means connected to the DC power supply, a DC / DC converter that charges and discharges the power storage means with a voltage of the DC power supply, a plurality of semiconductor switch elements, and the A power conversion device comprising a three-level inverter configured to drive a load with a voltage of the DC power supply, wherein the voltage of the power storage means is a voltage of the DC power supply. Of the load, one terminal of the load is connected to the other terminal of the power storage means, and the other terminal of the power storage means is connected to the neutral point voltage terminal of the three-level inverter. The control signal is generated so that the voltage at the other terminal of the load is controlled based on the voltage of the power storage means.

  A DC power supply and a DC / DC converter having one terminal connected to the storage means connected to the DC power supply and charging / discharging the storage means with a voltage of the DC power supply; and the storage means of the DC power supply; A first inverter that is connected between a terminal that is not connected and the other terminal of the power storage means and drives a first load, and a terminal that is connected between the terminals of the power storage means and drives a second load A power converter comprising a second inverter, and a control means for generating control signals for a plurality of semiconductor switch elements constituting the first inverter and the second inverter, wherein the control means includes the first inverter and The voltage command of the second inverter is adjusted to control charging / discharging of the power storage means.

  In addition, the DC power supply and one terminal connected to the power storage means connected to the DC power supply, and having a series connection body of semiconductor switch elements connected between the DC power supply terminals, the voltage of the DC power supply An inverter for driving a load with the voltage of the DC power source, comprising: a DC / DC converter for charging and discharging the power storage means; and a plurality of semiconductor switch elements and a control means for generating a control signal for the semiconductor switch elements. The power conversion device is provided, wherein the voltage of the power storage means is approximately ½ of the voltage of the DC power supply, and one terminal of the load is connected to a connection point of the series connection body of the semiconductor switch elements. The control signal is generated so as to control the voltage at the other terminal of the load with reference to the voltage at the connection point of the series connection body of the semiconductor switch elements.

  In addition, the DC power supply and one terminal connected to the power storage means connected to the DC power supply, and having a series connection body of semiconductor switch elements connected between the DC power supply terminals, the voltage of the DC power supply And a DC / DC converter for charging / discharging the power storage means, and a plurality of semiconductor switch elements and a control means for generating a control signal for the semiconductor switch elements, and driving the load with the voltage of the DC power supply. A power conversion device including an inverter, wherein the voltage of the power storage means is approximately ½ of the voltage of the DC power supply, and one terminal of the load is connected to a series connection body of the semiconductor switch elements. The other terminal of the power storage means is connected to a neutral point voltage terminal of the three-level inverter, and the voltage of the other terminal of the load is connected in series to the semiconductor switch element. The voltage of the body of the connecting point is obtained so as to generate the control signal to control the reference.

  The present invention relates to a DC power supply and a DC / DC converter in which one terminal is connected to a power storage means connected to the DC power supply, and charges / discharges the power storage means with a voltage of the DC power supply, and a plurality of semiconductor switch elements And a control means for generating a control signal for the semiconductor switch element, and comprising an inverter that drives a load with the voltage of the DC power supply, wherein the voltage of the power storage means is the voltage of the DC power supply. The terminal of the load is connected to the other terminal of the power storage means, and the voltage at the other terminal of the load is controlled based on the voltage of the power storage means. Since the control signal is generated, the number of semiconductor switch elements can be reduced in the entire device, and the size of the device can be reduced.

  Further, a higher-performance three-level inverter can be applied without an additional neutral point voltage generation circuit, and the size of the apparatus can be reduced by the amount that the neutral point voltage generation circuit is unnecessary.

Embodiment 1 FIG.
FIG. 1 is a circuit configuration diagram showing a configuration of a power conversion device according to Embodiment 1 of the present invention. In FIG. 1, a DC power source 1 is constituted by a DC power generation device such as a fuel cell or a solar cell, and an electric storage means 2 is constituted by a battery or a capacitor. The negative terminal N of the DC power source 1 and the negative terminal N of the power storage means 2 are connected. Between the positive terminal P and the negative terminal N of the DC power supply 1, a series connection body of the semiconductor switch elements 4, 5 is connected, and the connection point A of the series connection body of the semiconductor switch elements 4, 5 and the positive electrode of the power storage means 2 are connected. A reactor 3 is connected to the terminal C. The semiconductor switch elements 4 and 5 and the reactor 3 constitute a DC / DC converter 100 and charge / discharge the power storage means 2. This charging / discharging is performed by controlling the semiconductor switch elements 4 and 5 by the converter control means 6. The three-phase motor 7 has one of its terminals (W) connected to the positive terminal C of the power storage means 2, and the other two terminals (U, V) are connected in series of semiconductor switch elements 8 and 9, respectively. The connection point BU is connected to the connection point BV of the serial connection body of the semiconductor switch elements 10 and 11. The series connection body of the semiconductor switch elements 8 and 9 and the series connection body of the semiconductor switch elements 10 and 11 are respectively connected between the positive terminal P and the negative terminal N of the DC power source 1 to constitute the inverter 200. It is controlled by the inverter control means 12.
Here, the semiconductor switch elements 4, 5, 8 to 11 are configured by an IGBT element and a diode connected in antiparallel to the IGBT element.

  If a power converter is comprised as mentioned above, it will become possible to drive the three-phase motor 7 with the semiconductor switches 8-11 which comprise the two-phase part of a normal inverter.

  Here, the power storage means 2 and the DC / DC converter 100 are provided for the use of regenerative power, which will be described later, and are not newly provided for the purpose of reducing the number of semiconductor switch elements of the inverter 200. Therefore, even if the inverter 200 is configured as shown in FIG. 1, the number of parts does not increase in parts other than the inverter 200.

Next, the operation of the power conversion device according to Embodiment 1 of the present invention will be described with reference to FIGS.
FIG. 2 is a waveform of each part showing the operation of the DC / DC converter 100. In the apparatus for driving the motor 7 from the DC power source 1 via the inverter 200 as shown in FIG. 1, when the motor 7 is decelerated, a regenerative operation in which power is returned from the motor 7 to the DC power source 1 occurs. However, when the DC power source 1 is a fuel cell or a solar cell, the regenerated electric power cannot be received. Therefore, it is necessary to store the regenerated electric power from the inverter 200 via the DC / DC converter 100. There is. The stored electric power is used by supplying electric power from the electric storage means 2 to the inverter 200 via the DC / DC converter 100 during a power running operation in which electric power is supplied from the DC power source 1 to the motor 7. Thus, the DC / DC converter 100 controls charging / discharging of the power storage means 2. In FIG. 2, Vpn is a voltage between terminals of the DC power supply 1, Vcn is a voltage between terminals of the power storage means 2, and the respective voltage values are Vdc1 and Vdc2. Whatever the ratio of Vdc1 and Vdc2, there is no effect on the charge / discharge operation of the power storage means 2, but Vdc2 is set to approximately ½ of Vdc1 for the operation of the inverter 200 described later. The potential of the connection point A of the series connection body of the semiconductor switch elements 4 and 5 is the potential of the positive terminal P of the DC power supply 1 when the semiconductor switch 4 is ON, and the potential of the negative terminal N of the DC power supply 1 when the semiconductor switch 5 is ON. Since it becomes a potential, the voltage Van between the connection point A of the series connection body of the semiconductor switch elements 4 and 5 and the negative terminal N of the DC power supply 1 has a rectangular waveform as shown in FIG. Since a voltage of (Van to Vdc2) is applied between the terminals of the reactor 3, the reactor current IL increases when the semiconductor switch 4 is on and decreases when the semiconductor switch 5 is on. Converter control means 6 controls the charge / discharge of power storage means 2 by controlling the ratio of the on-time of semiconductor switch 4 and semiconductor switch 5 to maintain the average value of reactor current IL at a desired value.

  FIG. 3 is a block diagram showing the configuration of the inverter control means 12. The inverter control means 12 generates gate signals for the semiconductor switch elements 8 to 11 so that the inverter 200 outputs a voltage as commanded. Since the motor 7 is controlled by the line voltage between the U, V, and W terminals, a circuit such as the inverter 200 in FIG. 1 can obtain the same performance as a normal three-phase inverter if the line voltage is equal. . Therefore, the voltages at the U and V terminals may be determined based on the W terminal where the voltage is fixed. The inverter control means 12 receives output voltage commands Vu_ref, Vv_ref, Vw_ref from a command generation means (not shown) and the voltage Vdc2 of the power storage means 2. Since the voltage commands Vu_ref, Vv_ref, and Vw_ref are voltages based on the neutral point of the three-phase voltage command, the potential of the W phase is fixed to the potential of the positive terminal C of the power storage unit 2 as shown in FIG. If it is, conversion of the voltage command is required. This conversion can be realized by obtaining line voltages between the U phase and the W phase and between the V phase and the W phase and adding them to the potential of the positive terminal C of the power storage means 2. For this reason, by subtracting the W-phase voltage command Vw_ref from the U-phase voltage command Vu_ref and the V-phase voltage command Vv_ref by the subtracting means 13 and 14 and then adding the voltage Vdc2 of the power storage means 2 by the adding means 15 and 16, A U-phase voltage command Vu_ref2 and a V-phase voltage command Vv_ref2 are obtained with reference to the potential of the negative terminal N of the power storage unit 2. The voltage commands Vu_ref2 and Vv_ref2 are compared with the triangular wave carriers generated by the triangular wave generating means 17 by the comparators 18 and 19, respectively, so that the U-phase and V-phase PWM signals, that is, the semiconductor switch elements 8, 9 and Gate signals of the semiconductor switch elements 10 and 11 are obtained.

  FIG. 4 shows the waveform of each part of the inverter control means 12 of FIG. When the voltage commands Vu_ref, Vv_ref, and Vw_ref are sine waves, the converted voltage commands Vu_ref2 and Vv_ref2 are also sine waves. As shown in the figure, the voltage commands Vu_ref2 and Vv_ref2 change positively and negatively around the voltage Vdc2 of the power storage means 2 that is a W-phase voltage. Since the voltage that can be output is limited by the voltage Vdc1 of the DC power supply 1, it is obvious that the amplitudes of Vu_ref2 and Vv_ref2 can be maximized when Vdc2 is ½ of Vdc1. This voltage command Vu_ref2 is compared with a triangular wave carrier Tri whose value changes between 0 and Vdc1 generated by the triangular wave generating means 17, and when the triangular wave carrier is larger, it is “L”, and when it is smaller, it is “H”. Thus, the gate signals of the semiconductor switch element 8 and the semiconductor switch element 9 are obtained. The semiconductor switch element 8 uses the gate signal as it is, and turns on the IGBT element when it is “H” and turns it off when it is “L”. The semiconductor switch element 9 inverts and uses the gate signal, and turns off the IGBT element when it is “H” and turns it on when it is “L”. The same applies to the voltage command Vv_ref2 and the semiconductor switch elements 10 and 11.

  FIG. 5 is a waveform of each part showing the operation of the inverter 200. As a result of the above-described operation of the inverter control means 12, the potential at the connection point BU of the series connection body of the semiconductor switch elements 8 and 9 is the potential at the positive terminal P of the DC power source 1 when the semiconductor switch 8 is on. 5 is at the potential of the negative terminal N of the DC power supply 1, the voltage Vun between the connection point BU of the series connection body of the semiconductor switch elements 8 and 9 and the negative terminal N of the DC power supply 1 is shown in FIG. It becomes a rectangular wave waveform as shown. Further, the voltage Vvn between the connection point BV of the series connection body of the semiconductor switch elements 10 and 11 and the negative terminal N of the DC power supply 1 and the voltage Vcn = Vdc2 = Vwn between the terminals of the storage means 2 are also shown in FIG. It becomes a waveform like this. Here, since the output phase voltages Vu, Vv, and Vw are voltages viewed from the neutral point of the output terminal voltages Vun, Vvn, and Vwn, the output terminal voltages Vun, Vvn, and Vwn are respectively (Vun + Vvn + Vwn) / 3. Is obtained by subtracting. As shown in FIG. 5, the phase voltages Vu, Vv, and Vw all have a voltage waveform that is a combination of rectangles, and the average values thereof match the voltage commands Vu_ref, Vv_ref, and Vw_ref. As a result, the phase currents Iu, Iv, Iw flowing through the motor 7 have a sine wave waveform including a PWM ripple, as shown.

  As described above, according to the power conversion device according to the first embodiment, the voltage of the power storage means 2 is used as it is as the voltage of one terminal of the motor 7 as the voltage of approximately half the voltage of the DC power supply 1. It is possible to drive a three-phase motor with four semiconductor switch elements by omitting two semiconductor switch elements for one phase. Therefore, the number of semiconductor switch elements can be reduced in the entire device, and the size of the device can be reduced.

  As is clear from the above description, the power conversion device according to the first embodiment operates autonomously with the configuration of FIG. Therefore, as shown in FIG. 6, it is obvious that the same effect can be obtained even when the power conversion device according to the first embodiment and the inverter 300 composed of six semiconductor switch elements are combined.

In the above description, the most common three-phase output inverter and three-phase motor are used as an example. However, two semiconductor switch elements for one phase can be omitted, but the invention is not limited to three-phase. . Accordingly, even in an inverter having four or more outputs (here, four phases) as shown in FIG. 7A and a single-phase inverter as shown in FIG. Two semiconductor switch elements for the phase can be omitted. Of course, the load of the inverter is not limited to the motor, and the same effect can be obtained with any load, whether a resistance load or a reactor load.
Embodiment 2. FIG.

FIG. 8 is a block diagram showing a configuration of inverter control means 12 of the power conversion device according to the second embodiment of the present invention. The other configuration is the same as that of the first embodiment shown in FIG. Further, since the operation of the DC / DC converter 100 is the same as that of the first embodiment, the description thereof is omitted.
The inverter control means 12 generates gate signals for the semiconductor switch elements 8 to 11 so that the inverter 200 outputs a voltage as commanded. Since the motor 7 is controlled by the line voltage between the U, V, and W terminals, a circuit such as the inverter 200 in FIG. 1 can obtain the same performance as a normal three-phase inverter if the line voltage is equal. . Therefore, the voltages at the U and V terminals may be determined based on the W terminal at which the voltage is fixed. At this time, even if a voltage component (for example, DC offset voltage) different from the main three-phase voltage command is superimposed, the motor 7 only generates torque pulsation, and the average value of pulsation becomes zero. Does not occur. Output voltage commands Vu_ref, Vv_ref, Vw_ref, an offset voltage command Voffset, and a voltage Vdc2 of the power storage unit 2 are input to the inverter control unit 12 from a command generation unit (not shown). Since the voltage commands Vu_ref, Vv_ref, and Vw_ref are voltages based on the neutral point of the three-phase voltage command, the potential of the W phase is fixed to the potential of the positive terminal C of the power storage unit 2 as shown in FIG. If it is, conversion of the voltage command is required. This conversion can be realized by obtaining line voltages between the U phase and the W phase and between the V phase and the W phase and adding them to the potential of the positive terminal C of the power storage means 2. Therefore, after subtracting the W-phase voltage command Vw_ref by the subtracting means 13 and 14 from the U-phase voltage command Vu_ref and the V-phase voltage command Vv_ref, the adding means 15 and 16 add the voltage Vdc2 of the power storage means 2. Further, the addition means 20 and 21 add the offset voltage command Voffset to obtain the U-phase voltage command Vu_ref3 and the V-phase voltage command Vv_ref3 with reference to the potential of the negative terminal N of the power storage means 2. The voltage commands Vu_ref3 and Vv_ref3 are compared with the triangular wave carrier Tri generated by the triangular wave generating means 17 by the comparing means 18 and 19, respectively, so that the U-phase and V-phase PWM signals, that is, the semiconductor switch elements 8, 9 And the gate signal of the semiconductor switch elements 10 and 11 is obtained.

  FIG. 9 shows the waveform of each part of the inverter control means 12 of FIG. When the voltage commands Vu_ref, Vv_ref, and Vw_ref are sine waves, the converted voltage commands Vu_ref3 and Vv_ref3 are also sine waves. As shown in the figure, the voltage commands Vu_ref3 and Vv_ref3 change positively or negatively with a value obtained by adding the offset voltage command Voffset to the voltage Vdc2 of the power storage unit 2 being a W-phase voltage. This voltage command Vu_ref3 is compared with a triangular wave carrier Tri whose value changes between 0 and Vdc1 generated by the triangular wave generating means 17, and when the triangular wave carrier is larger, it is “L”, and when it is smaller, it is “H”. As a result, gate signals of the semiconductor switch elements 8 and 9 are obtained. The semiconductor switch element 8 uses the gate signal as it is, and turns on the IGBT element when it is “H” and turns it off when it is “L”. The semiconductor switch element 9 inverts and uses the gate signal, and turns off the IGBT element when it is “H” and turns it on when it is “L”. The same applies to the voltage command Vv_ref3 and the semiconductor switch elements 10 and 11.

  In the present embodiment, by adding the offset voltage command Voffset, the gate signals of the semiconductor switch elements 8 and 9 and the gate signals of the semiconductor switch elements 10 and 11 are both longer than “L”. . As a result, the average value of the U-phase and V-phase output voltages is higher than the W-phase output voltage by the offset voltage command Voffset. Due to this voltage difference, current flows from the U phase and the V phase to the W phase, so that the phase current Iw flowing through the motor 7 has a sine wave waveform on which the offset current Ioffset is superimposed as shown in the figure. The offset current Ioffset can be controlled to an arbitrary value by changing the offset voltage command Voffset. Accordingly, the offset current Ioffset can be controlled by the offset voltage command Voffset independently of the torque of the motor 7 controlled by the three-phase voltage commands Vu_ref, Vv_ref, and Vw_ref.

  As shown in FIG. 1, since the W phase of the motor 7 is connected to the positive terminal C of the power storage means 2, the offset current Ioffset superimposed on the W phase current Iw becomes a current for charging and discharging the power storage means 2, The same function as the DC / DC converter 100 is performed. Therefore, the current of the DC / DC converter 100 can be reduced by the offset current Ioffset, and by reducing the current rating of the semiconductor switch element used in the DC / DC converter 100, the size of the semiconductor switch element, and consequently The size of the device can be reduced.

Similar to the power conversion device according to the first embodiment, the power conversion device according to the second embodiment can achieve the same effect even when combined with an inverter composed of six semiconductor switch elements. In addition, the same effect can be obtained in an inverter having an output of three or more phases and a single-phase inverter. Furthermore, the same effect can be obtained even with a load other than the motor.
Embodiment 3 FIG.

  FIG. 10 is a circuit configuration diagram showing a power conversion device according to Embodiment 3 of the present invention. In FIG. 10, the DC power source 1, the power storage means 2, the reactor 3, the semiconductor switch elements 4, 5, and the converter control means 6 are the same as those in the first embodiment shown in FIG. The inverter 400 includes a series connection body of the semiconductor switch elements 22, 23, 24, and 25, a series connection body of the semiconductor switch elements 28, 29, 30, and 31, and a series connection body of the semiconductor switch elements 34, 35, 36, and 37. Are connected between the terminals of the DC power source 1. Each semiconductor switch element is controlled by the inverter control means 40. Of the three terminals U, V, and W of the motor 7, the terminal U is a connection point BU between the semiconductor switch element 23 and the semiconductor switch element 24, and the terminal V is a connection point between the semiconductor switch element 29 and the semiconductor switch element 30. The terminal W is connected to the connection point BW of the semiconductor switch element 35 and the semiconductor switch element 36 to BV. Further, the connection point between the semiconductor switch element 22 and the semiconductor switch element 23, the connection point between the semiconductor switch element 24 and the semiconductor switch element 25, the connection point between the semiconductor switch element 28 and the semiconductor switch element 29, the semiconductor switch element 30 and the semiconductor. The connection point between the switch element 31, the connection point between the semiconductor switch element 34 and the semiconductor switch element 35, and the connection point between the semiconductor switch element 36 and the semiconductor switch element 37 are respectively diodes 26, 27, 32, 33, 38, 39 is connected to the positive terminal C of the power storage means 2. Here, the semiconductor switch elements 22 to 25, 28 to 31, and 34 to 37 are configured by an IGBT element and a diode connected in reverse parallel to the IGBT element.

If the power conversion device is configured as described above, the three-phase motor 7 can be driven by a three-level inverter instead of a normal two-level inverter.
Here, normally, in order to constitute a three-level inverter, the neutral point potential of the DC power supply 1 is necessary, and it is necessary to create the neutral point potential by another circuit means or the like. Then, the DC / DC converter 100 sets the voltage of the power storage means 2 to approximately a half of the voltage of the DC power source 1 and uses this voltage as a neutral point potential, thereby omitting additional circuit means.

Next, the operation of the power converter according to Embodiment 3 of the present invention will be described with reference to FIGS. Since the operation of the DC / DC converter 100 constituted by the reactor 3, the semiconductor switch elements 4 and 5, and the converter control means 6 is the same as that of FIG.
FIG. 11 is a block diagram showing the configuration of the inverter control means 40. The inverter control means 40 generates the gate signals of the semiconductor switch elements 22 to 25, 28 to 31, and 34 to 37 so that the inverter 400 outputs a commanded voltage. Output voltage commands Vu_ref, Vv_ref, Vw_ref from command generation means (not shown) are input to the inverter control means 40. By comparing the voltage commands Vu_ref, Vv_ref and Vw_ref with the triangular wave carrier Tri1 generated by the first triangular wave generating means 41 and the triangular wave carrier Tri2 generated by the second triangular wave generating means 42 by the comparing means 43 to 48. , U-phase, V-phase, and W-phase PWM signals, that is, gate signals of the semiconductor switch elements 22 to 25, the semiconductor switch elements 28 to 31, and the semiconductor switch elements 34 to 37 are obtained.

  FIG. 12 shows the waveform of each part of the inverter control means 40 shown in FIG. The voltage command Vu_ref is compared with the triangular wave carrier Tri1 whose value changes between 0 and Vdc2 generated by the triangular wave generating means 41. When the triangular wave carrier is larger, it is “L”, and when it is smaller, it is “H”. Thus, gate signals of the semiconductor switch element 22 and the semiconductor switch element 24 are obtained, and the voltage command Vu_ref is compared with the triangular wave carrier Tri2 whose value changes between −Vdc2 to 0 generated by the triangular wave generating means 42. By setting “L” when the triangular wave carrier is larger and “H” when smaller, the gate signals of the semiconductor switch element 23 and the semiconductor switch element 25 can be obtained. The semiconductor switch elements 22 and 23 use this gate signal as it is, and turn on the IGBT element when it is “H”, and turn it off when it is “L”. The semiconductor switch elements 24 and 25 invert and use the gate signal, and turn off the IGBT element when “H” and turn on the IGBT element when “L”. The same applies to the voltage command Vv_ref and the semiconductor switch elements 28 to 31 and the voltage command Vw_ref and the semiconductor switch elements 34 to 37.

  FIG. 13 is a waveform of each part showing the operation of the inverter 400. As a result of the above-described operation of the inverter control means 40, the potential at the connection point BU of the semiconductor switch elements 23, 24 is the potential of the positive terminal P of the DC power source 1 and the semiconductor switches 24, 25 when the semiconductor switches 22, 23 are on. Since the potential of the negative terminal N of the DC power source 1 is at the time of ON, and the potential of the positive terminal C of the power storage means 2 when the semiconductor switches 23, 24 are on, the connection point BU of the series connection body of the semiconductor switch elements 23, 24 And the negative terminal N of the DC power supply 1 have a rectangular waveform as shown in FIG. Further, a voltage Vvn between the connection point BV of the semiconductor switch elements 29 and 30 and the negative terminal N of the DC power supply 1, and a voltage between the connection point BW of the semiconductor switch elements 35 and 36 and the negative terminal N of the DC power supply 1. Vwn also has a waveform as shown in FIG. Here, since the output phase voltages Vu, Vv, and Vw are voltages viewed from the neutral point of the output terminal voltages Vun, Vvn, and Vwn, the output terminal voltages Vun, Vvn, and Vwn are respectively (Vun + Vvn + Vwn) / 3. Is obtained by subtracting. The phase voltages Vu, Vv, and Vw are stepped voltage waveforms, and the average values thereof coincide with the voltage commands Vu_ref, Vv_ref, and Vw_ref. As a result, the phase currents Iu, Iv, Iw flowing through the motor 7 have a sine wave waveform including a PWM ripple, as shown. Further, this waveform is a smoother waveform than in the case of the first embodiment, and the operation of the motor becomes smoother.

  As described above, according to the power conversion device according to the third embodiment, the voltage of power storage means 2 is set to approximately half the voltage of DC power supply 1 and used as the neutral point potential of the three-level inverter. Thus, it is possible to apply a three-level inverter without adding a circuit for creating a neutral point potential. Therefore, an additional circuit can be omitted, and the size of the device can be reduced.

  As is clear from the above description, the power conversion device according to the third embodiment operates autonomously with the configuration of FIG. Therefore, as shown in FIG. 14, it is obvious that the same effect can be obtained by combining the power conversion device according to the third embodiment and the two-level inverter 300 composed of six semiconductor switch elements. In addition, it is obvious that the same effect can be obtained by combining the inverter 200 constituted by four semiconductor switch elements according to the first embodiment.

In addition, the power conversion device according to the third embodiment can obtain the same effects in both a single-phase inverter and an inverter having three or more outputs, similarly to the power conversion device according to the first embodiment. Furthermore, the same effect can be obtained even with a load other than the motor.
Embodiment 4 FIG.

FIG. 15 is a block diagram showing a configuration of inverter control means 40 of the power conversion device according to the fourth embodiment of the present invention. The other configuration is the same as that of the third embodiment shown in FIG. The operation of the DC / DC converter 100 is the same as that in FIG.
The inverter control means 40 generates the gate signals of the semiconductor switch elements 22 to 25, 28 to 31, and 34 to 37 so that the inverter 400 outputs a commanded voltage. Since the motor 7 is controlled by the line voltage between the U, V, and W terminals, even if the same voltage (for example, DC offset voltage) is added to all three phases, the line voltage does not change, so the same performance is obtained. It is done. Therefore, the voltages at the U and V terminals may be determined based on the W terminal where the voltage is fixed. At this time, even if a voltage component (for example, DC offset voltage) different from the main three-phase voltage command is superimposed, the motor 7 only generates torque pulsation, and the average value of pulsation becomes zero. Does not occur. The inverter control means 40 receives output voltage commands Vu_ref, Vv_ref, Vw_ref and an offset voltage command Voffset from command generation means (not shown). By adding the offset voltage command Voffset to the voltage commands Vu_ref, Vv_ref, Vw_ref by the adding means 49 to 51, the U-phase voltage command Vu_ref4, the V-phase voltage command Vv_ref4, and the W-phase voltage command Vw_ref4 having an offset are obtained. By comparing the voltage commands Vu_ref4, Vv_ref4, and Vw_ref4 with the triangular wave carrier Tri1 generated by the first triangular wave generating means 41 and the triangular wave carrier Tri2 generated by the second triangular wave generating means 42 by the comparison means 43-48. , U-phase, V-phase, and W-phase PWM signals, that is, gate signals of the semiconductor switch elements 22 to 25, the semiconductor switch elements 28 to 31, and the semiconductor switch elements 34 to 37 are obtained.

  FIG. 16 shows the waveform of each part of the inverter control means 40 of FIG. When the voltage commands Vu_ref, Vv_ref, and Vw_ref are sine waves, the converted voltage commands Vu_ref4, Vv_ref4, and Vw_ref4 are also sine waves. The voltage commands Vu_ref4, Vv_ref4, and Vw_ref4 change positively and negatively around the offset voltage command Voffset as shown in the figure. This voltage command Vu_ref4, a triangular wave carrier Tri1 whose value changes between 0 and Vdc2 generated by the triangular wave generating means 41, and a triangular wave carrier Tri2 whose value changes between -Vdc2 and 0 generated by the triangular wave generating means 42 Are respectively set to “L” when the triangular wave carrier is larger, and “H” when the triangular wave carrier is smaller, so that the gate signals of the semiconductor switch elements 22 and 24 and the gate signals of the semiconductor switch elements 23 and 25 are obtained. It is done. The semiconductor switch elements 22 and 23 use this gate signal as it is, and turn on the IGBT element when it is “H”, and turn it off when it is “L”. The semiconductor switch elements 24 and 25 invert and use the gate signal, and turn off the IGBT element when “H” and turn on the IGBT element when “L”.

  By adding the offset voltage command Voffset, the “H” time of the gate signals of the semiconductor switch elements 22, 24 becomes longer than the “L” time of the gate signals of the semiconductor switch elements 23, 25. When the gate signal of the semiconductor switch elements 22 and 24 is “H”, a current flows from the positive terminal P of the DC power supply 1, and from the negative terminal N of the DC power supply 1 when the gate signal of the semiconductor switch elements 23 and 25 is “L”. Since the current flows, if the “H” time of the gate signals of the semiconductor switch elements 22 and 24 and the “L” time of the gate signals of the semiconductor switch elements 23 and 25 are different, the difference current becomes a neutral point potential, that is, And flows to the positive terminal C of the power storage means 2. The same applies to the voltage command Vv_ref4 and the semiconductor switch elements 28 to 31, and the voltage command Vw_ref4 and the semiconductor switch elements 34 to 37.

  As a result, when the offset voltage command Voffset is changed, the phase currents Iu, Iv, and Iw flowing through the motor 7 become a sine wave waveform including a PWM ripple as shown in the figure, but do not include an offset component, but a current at a neutral point potential. That is, the current flowing through the positive terminal C of the power storage means 2 has a waveform in which the offset current Ioffset is superimposed, and the average value is not zero. The offset current Ioffset can be controlled to an arbitrary value by changing the offset voltage command Voffset. Accordingly, the offset current Ioffset can be controlled by the offset voltage command Voffset independently of the torque of the motor 7 controlled by the three-phase voltage commands Vu_ref, Vv_ref, and Vw_ref.

  This offset current Ioffset becomes a current for charging / discharging the power storage means 2 and functions in the same manner as the DC / DC converter 100. Therefore, the current of the DC / DC converter 100 can be reduced by the offset current Ioffset, and by reducing the current rating of the semiconductor switch element used in the DC / DC converter 100, the size of the semiconductor switch element, and consequently The size of the device can be reduced.

Similarly to the power conversion device according to the third embodiment, the power conversion device according to the fourth embodiment can also be combined with the inverter composed of six semiconductor switch elements, so that the four semiconductor switch elements according to the first embodiment are used. The same effect can be obtained even when combined with the inverter configured as described above. In addition, the same effect can be obtained in an inverter having an output of three or more phases and a single-phase inverter. Furthermore, the same effect can be obtained even with a load other than the motor.
Embodiment 5 FIG.

  FIG. 17 is a circuit configuration diagram showing a power conversion device according to Embodiment 5 of the present invention. In FIG. 17, the DC power source 1, the power storage means 2, the reactor 3, the semiconductor switch elements 4, 5, and the converter control means 6 are the same as those in the first embodiment shown in FIG. One terminal (W) of the motor 7 is connected to the positive terminal C of the power storage means 2, and the other two terminals (U, V) are connected in series with the semiconductor switch elements 22, 23, 24, 25, respectively. Connection point BU between semiconductor switch element 23 and semiconductor switch element 24 in the connection body and connection point BV between semiconductor switch element 29 and semiconductor switch element 30 in the series connection body of semiconductor switch elements 28, 29, 30, 31. Has been. The series connection body of the semiconductor switch elements 22, 23, 24, 25 and the series connection body of the semiconductor switch elements 28, 29, 30, 31 are connected between the terminals of the DC power source 1 to constitute the inverter 500. It is controlled by the inverter control means 52. Further, the connection point between the semiconductor switch element 22 and the semiconductor switch element 23, the connection point between the semiconductor switch element 24 and the semiconductor switch element 25, the connection point between the semiconductor switch element 28 and the semiconductor switch element 29, the semiconductor switch element 30 and the semiconductor. The connection point with the switch element 31 is connected to the positive terminal C of the power storage means 2 via the diodes 26, 27, 32 and 33, respectively. Here, the semiconductor switch elements 22 to 25 and 28 to 31 are composed of an IGBT element and a diode connected in antiparallel to the IGBT element.

If the power conversion device is configured as described above, the three-phase motor 7 can be driven by a three-level inverter instead of a normal two-level inverter, and two phases of a normal three-level inverter can be used. The three-phase motor 7 can be driven by the semiconductor switch elements 22 to 25 and 28 to 31 that are configured.
Here, normally, in order to constitute a three-level inverter, the neutral point potential of the DC power supply 1 is necessary, and it is necessary to create the neutral point potential by another circuit means or the like. Then, as in the third embodiment, the DC / DC converter 100 sets the voltage of the power storage means 2 to approximately half that of the DC power source 1 and uses this voltage as the neutral point potential, thereby providing additional circuit means. Is omitted.

Next, the operation of the power conversion apparatus according to the fifth embodiment of the present invention will be described with reference to FIGS. Since the operation of the DC / DC converter 100 constituted by the reactor 3, the semiconductor switch elements 4 and 5, and the converter control means 6 is the same as that of FIG.
FIG. 18 is a block diagram showing the configuration of the inverter control means 52. The inverter control means 52 generates gate signals for the semiconductor switch elements 22 to 25 and 28 to 31 so that the inverter 500 outputs a voltage as commanded. Since the motor 7 is controlled by the line voltage between the U, V, and W terminals, a circuit like the inverter 500 in FIG. 17 can obtain the same performance as a normal three-phase inverter if the line voltage is equal. . Therefore, the voltages at the U and V terminals may be determined based on the W terminal where the voltage is fixed. The inverter control means 52 receives output voltage commands Vu_ref, Vv_ref, Vw_ref from a command generation means (not shown) and the voltage Vdc2 of the power storage means 2. Since the voltage commands Vu_ref, Vv_ref, and Vw_ref are voltages based on the neutral point of the three-phase voltage command, the W-phase potential is fixed to the potential of the positive terminal C of the power storage unit 2 as shown in FIG. If it is, conversion of the voltage command is required. This conversion can be realized by obtaining line voltages between the U phase and the W phase and between the V phase and the W phase and adding them to the potential of the positive terminal C of the power storage means 2. For this reason, by subtracting the W-phase voltage command Vw_ref from the U-phase voltage command Vu_ref and the V-phase voltage command Vv_ref by the subtracting means 13 and 14, and then adding the voltage Vdc2 of the power storage means 2 by the adding means 15 and 16, A U-phase voltage command Vu_ref2 and a V-phase voltage command Vv_ref2 are obtained with reference to the potential of the negative terminal N of the power storage unit 2. By comparing the voltage commands Vu_ref2 and Vv_ref2 with the triangular wave carrier Tri3 generated by the first triangular wave generating means 53 and the triangular wave carrier Tri4 generated by the second triangular wave generating means 54 by the comparing means 43 to 46, U-phase and V-phase PWM signals, that is, gate signals of the semiconductor switch elements 22 to 25 and the semiconductor switch elements 28 to 31 are obtained.

  FIG. 19 shows the waveform of each part of the inverter control means 52 of FIG. When the voltage commands Vu_ref, Vv_ref, and Vw_ref are sine waves, the converted voltage commands Vu_ref2 and Vv_ref2 are also sine waves. As shown in the figure, the voltage commands Vu_ref2 and Vv_ref2 change positively and negatively around the voltage Vdc2 of the power storage means 2 that is a W-phase voltage. A voltage command Vu_ref2, a triangular wave carrier Tri3 whose value changes between Vdc2 to Vdc1 generated by the triangular wave generating means 53, and a triangular wave carrier Tri4 whose value changes between 0 and Vdc2 generated by the triangular wave generating means 54, respectively. In comparison, when the triangular wave carrier is larger, “L” is set, and when it is smaller, “H”, the gate signals of the semiconductor switch elements 22 and 24 and the gate signals of the semiconductor switch elements 23 and 25 are obtained. The semiconductor switch elements 22 and 23 use this gate signal as it is, and turn on the IGBT element when it is “H”, and turn it off when it is “L”. The semiconductor switch elements 24 and 25 invert and use the gate signal, and turn off the IGBT element when “H” and turn on the IGBT element when “L”. The same applies to the voltage command Vv_ref and the semiconductor switch elements 28 to 31.

  FIG. 20 is a waveform of each part showing the operation of the inverter 500. As a result of the above-described operation of the inverter control means 52, the potential at the connection point BU of the semiconductor switch elements 23, 24 is the potential of the positive terminal P of the DC power source 1 and the semiconductor switches 24, 25 when the semiconductor switches 22, 23 are on. Since the potential of the negative terminal N of the DC power source 1 is at the time of ON, and the potential of the positive terminal C of the power storage means 2 when the semiconductor switches 23, 24 are on, the connection point BU of the series connection body of the semiconductor switch elements 23, 24 And the negative terminal N of the DC power supply 1 have a rectangular wave waveform as shown in FIG. Further, the voltage Vvn between the connection point BV of the semiconductor switch elements 29 and 30 and the negative terminal N of the DC power supply 1 and the inter-terminal voltage Vcn = Vdc2 = Vwn of the power storage means 2 also have waveforms as shown in FIG. Become. Here, since the output phase voltages Vu, Vv, and Vw are voltages viewed from the neutral point of the output terminal voltages Vun, Vvn, and Vwn, the output terminal voltages Vun, Vvn, and Vwn are respectively (Vun + Vvn + Vwn) / 3. Is obtained by subtracting. The phase voltages Vu, Vv, and Vw are stepped voltage waveforms, and the average values thereof coincide with the voltage commands Vu_ref, Vv_ref, and Vw_ref. As a result, the phase currents Iu, Iv, Iw flowing through the motor 7 have a sine wave waveform including a PWM ripple, as shown.

  As described above, according to the power conversion device according to the third embodiment, the voltage of power storage means 2 is set to approximately half the voltage of DC power supply 1 and used as the neutral point potential of the three-level inverter. Thus, it is possible to apply a three-level inverter without adding a circuit for creating a neutral point potential. As a result, the motor can be operated more smoothly. Further, since the voltage of the power storage means 2 is used as it is as the voltage of one terminal of the motor 7, it is possible to drive the three-phase motor with eight semiconductor switch elements by omitting the semiconductor switch elements for one phase. Become. As described above, even when a three-level inverter is applied, there is no need for an additional circuit, the number of semiconductor switch elements can be reduced, and the size of the device can be reduced.

  As is clear from the above description, the power conversion device according to the fifth embodiment operates autonomously with the configuration of FIG. Therefore, as shown in FIG. 21, it is obvious that the same effect can be obtained by combining the power conversion device according to the fifth embodiment and the two-level inverter 300 composed of six semiconductor switch elements. In addition, it is obvious that the same effect can be obtained by combining the inverter 200 constituted by four semiconductor switch elements according to the first embodiment. Further, it is obvious that the same effect can be obtained even when the three-level inverter 400 according to the third embodiment is combined.

In addition, the power conversion device according to the fifth embodiment can obtain the same effect in both an inverter having three or more phases and a single-phase inverter, as in the power conversion device according to the first embodiment. Furthermore, the same effect can be obtained even with a load other than the motor.
Embodiment 6 FIG.

FIG. 22 is a block diagram showing a configuration of inverter control means 52 of the power conversion device according to the sixth embodiment of the present invention. The other configuration is the same as that of the fifth embodiment shown in FIG. Further, since the operation of DC / DC converter 100 is the same as that of FIG. 2 of the first embodiment of the present invention, description thereof is omitted.
The inverter control means 52 generates gate signals for the semiconductor switch elements 22 to 25 and 28 to 31 so that the inverter 500 outputs a voltage as commanded. Since the motor 7 is controlled by the line voltage between the U, V, and W terminals, a circuit like the inverter 500 in FIG. 17 can obtain the same performance as a normal three-phase inverter if the line voltage is equal. . Therefore, the voltages at the U and V terminals may be determined based on the W terminal at which the voltage is fixed. At this time, even if a voltage component (for example, DC offset voltage) different from the main three-phase voltage command is superimposed, the motor 7 only generates torque pulsation, and the average value of pulsation becomes zero, so uniform torque Does not occur. Output voltage commands Vu_ref, Vv_ref, Vw_ref, an offset voltage command Voffset, and a voltage Vdc2 of the power storage unit 2 are input to the inverter control unit 52 from a command generation unit (not shown). Since the voltage commands Vu_ref, Vv_ref, and Vw_ref are voltages based on the neutral point of the three-phase voltage command, the W-phase potential is fixed to the potential of the positive terminal C of the power storage unit 2 as shown in FIG. If it is, conversion of the voltage command is required. This conversion can be realized by obtaining the line voltage between the U phase and the phase and between the V phase and the W phase and adding it to the potential of the positive terminal C of the power storage means 2. Therefore, after subtracting the W-phase voltage command Vw_ref by the subtracting means 13 and 14 from the U-phase voltage command Vu_ref and the V-phase voltage command Vv_ref, the adding means 15 and 16 add the voltage Vdc2 of the power storage means 2. Further, the addition means 20 and 21 add the offset voltage command Voffset, thereby obtaining the U-phase voltage command Vu_ref3 and the V-phase voltage command Vv_ref3 based on the potential of the negative terminal N of the power storage means 2. By comparing the voltage commands Vu_ref3 and Vv_ref3 with the triangular wave carrier Tri3 generated by the first triangular wave generating means 53 and the triangular wave carrier Tri4 generated by the second triangular wave generating means 54 by the comparing means 43 to 46, U-phase and V-phase PWM signals, that is, gate signals of the semiconductor switch elements 22 to 25 and the semiconductor switch elements 28 to 31 are obtained.

  FIG. 23 shows the waveform of each part of the inverter control means 52 of FIG. When the voltage commands Vu_ref, Vv_ref, and Vw_ref are sine waves, the converted voltage commands Vu_ref3 and Vv_ref3 are also sine waves. As shown in the figure, the voltage commands Vu_ref3 and Vv_ref3 change positively and negatively around a value obtained by adding the offset voltage command Voffset to the W-phase potential Vdc2. The voltage command Vu_ref3, a triangular wave carrier Tri3 whose value changes between vdc2 to Vdc1 generated by the triangular wave generating means 53, and a triangular wave carrier Tri4 whose value changes between 0 and Vdc2 generated by the triangular wave generating means 54. Each is compared, and when the triangular wave carrier is larger, it is set to “L”, and when it is smaller, it is set to “H”. . The semiconductor switch elements 22 and 23 use this gate signal as it is, and turn on the IGBT element when it is “H”, and turn it off when it is “L”. The semiconductor switch elements 24 and 25 invert and use the gate signal, and turn off the IGBT element when “H” and turn on the IGBT element when “L”.

  By adding the offset voltage command Voffset, the “H” time of the gate signals of the semiconductor switch elements 22, 24 becomes longer than the “L” time of the gate signals of the semiconductor switch elements 23, 25. When the gate signal of the semiconductor switch elements 22 and 24 is “H”, a current flows from the positive terminal P of the DC power supply 1, and from the negative terminal N of the DC power supply 1 when the gate signal of the semiconductor switch elements 23 and 25 is “L”. Since the current flows, if the “H” time of the gate signals of the semiconductor switch elements 22 and 24 and the “L” time of the gate signals of the semiconductor switch elements 23 and 25 are different, the difference current becomes a neutral point potential, that is, And flows to the positive terminal C of the power storage means 2. The same applies to the voltage command Vv_ref4 and the semiconductor switch elements 28-31.

  Also, by adding the offset voltage command Voffset, the average value of the U-phase and V-phase output voltages is higher than the W-phase output voltage by the offset voltage command Voffset. Due to this voltage difference, current flows from the U phase and the V phase to the W phase, so that the phase current Iw flowing through the motor 7 has a sine wave waveform on which the offset current Ioffset is superimposed as shown in the figure. The offset current Ioffset can be controlled to an arbitrary value by changing the offset voltage command Voffset. Accordingly, the offset current Ioffset can be controlled by the offset voltage command Voffset independently of the torque of the motor 7 controlled by the three-phase voltage commands Vu_ref, Vv_ref, and Vw_ref.

  The offset current Ioffset is a current for charging / discharging the power storage unit 2 and functions in the same manner as a DC / DC converter including the reactor 3, the semiconductor switch elements 4, 5 and the converter control unit 6. Therefore, the current of the DC / DC converter can be reduced by the amount of the offset current Ioffset, and the current rating of the semiconductor switch element used in the DC / DC converter is reduced. Can be reduced.

Similarly to the power conversion device according to the fifth embodiment, the power conversion device according to the sixth embodiment can also be combined with an inverter composed of six semiconductor switch elements, so that the four semiconductor switch elements according to the first embodiment are used. The same effect can be obtained by combining with the inverter configured as described above or with the three-level inverter according to the third embodiment. In addition, the same effect can be obtained in an inverter having an output of three or more phases and a single-phase inverter. Furthermore, the same effect can be obtained even with a load other than the motor.
Embodiment 7 FIG.

FIG. 24 is a circuit configuration diagram showing a power conversion device according to Embodiment 7 of the present invention. In FIG. 24, DC power supply 1, power storage means 2, reactor 3, semiconductor switch elements 4, 5, and converter control means 6 are the same as those in the first embodiment shown in FIG. The semiconductor switch elements 55 to 60 constitute a first inverter 600 connected between the positive terminal P of the DC power supply 1 and the positive terminal C of the power storage means 2, and drive the first motor 67. The semiconductor switch elements 61 to 66 constitute a second inverter 700 connected between the terminals of the power storage means 2 and drive the second motor 68. The semiconductor switch elements 55 to 66 are controlled by the inverter control means 69. Here, the semiconductor switch elements 55 to 66 are constituted by an IGBT element and a diode connected in antiparallel to the IGBT element.
In the present embodiment, two inverters are connected as shown in FIG. 24, and the DC / DC converter 100 is used to set the voltage of the power storage means 2 to approximately half the voltage of the DC power supply 1. It is used as.

  Next, the operation of the power conversion device according to the seventh embodiment of the present invention will be described. The operation of the DC / DC converter 100 is the same as that in FIG. Since the first inverter 600 composed of the semiconductor switch elements 55 to 60 is connected between the positive terminal P of the DC power source 1 and the positive terminal C of the power storage means 2, the current for driving the first motor 67. Charges the power storage means 2 via the DC power supply 1. On the other hand, since the second inverter 700 composed of the semiconductor switch elements 61 to 66 is connected between the terminals of the power storage means 2, the current for driving the second motor 68 causes the power storage means 2 to Discharge. Therefore, the power storage means 2 can be charged / discharged by adjusting the driving power of the first motor 67 and the second motor 68.

  FIG. 25 is a block diagram showing the configuration of the inverter control means 69 for realizing the above operation. In a normal time, the inverter control unit 69 outputs the output voltage commands Vu_ref_600, Vv_ref_600, Vw_ref_600 of the inverter 600 from the command generation unit (not shown), and the output voltage commands Vu_ref_700, Vv_ref_700, Vw_ref_700 of the inverter 700 by the comparators 73 to 78, respectively. By comparing with the triangular wave carrier generated by the triangular wave generating means 79, the gate signals of the semiconductor switch elements 55 to 66 in the normal state are obtained. When controlling charging / discharging of the power storage means 2, the inverter control means 69 outputs the output voltage command Vu_ref_600x of the inverter 600 whose voltage difference is Vdiff by the command generation means 71 based on the differential voltage command Vdiff from the command generation means (not shown). , Vv_ref_600x, Vw_ref_600x, and output voltage commands Vu_ref_700x, Vv_ref_700x, Vw_ref_700x of the inverter 700 are newly generated. The output voltage commands Vu_ref_600x, Vv_ref_600x, Vw_ref_600x, Vu_ref_700x, Vv_ref_700x, Vw_ref_700x are selected by the switching unit 72 by the switching signal SW from the command generation unit (not shown), and the triangular wave generating unit 79 is generated by the comparators 73 to 78, respectively. By comparing with the triangular wave carrier, the gate signals of the semiconductor switch elements 55 to 66 when the charge / discharge of the power storage means 2 is controlled are obtained.

  FIG. 26 shows the waveforms of the respective parts of the power conversion device according to Embodiment 7 when charging / discharging of power storage means 2 is controlled. The output voltage commands Vu_ref_600x, Vv_ref_600x, Vw_ref_600x of the inverter 600 and the output voltage commands Vu_ref_700x, Vv_ref_700x, Vw_ref_700x of the inverter 700 have different amplitudes based on the differential voltage command Vdiff as shown in the figure. By this command, the voltage Vu1-c between the U1 terminal of the inverter 600 and the C terminal of the power storage means 2 and the voltage Vu2-n between the U2 terminal of the inverter 700 and the N terminal of the DC power supply 1 are respectively illustrated. It can be seen that Vu1-c outputs a higher voltage than Vu2-n. In order to simplify the description, if the first motor 67 and the second motor 68 are the same motor and the loads are equal, the voltage difference appears as a current difference as it is. The currents of the DC buses of the inverter 600 and the inverter 700 are illustrated as Idc_600 and Idc_700, respectively, but the inverter 600 has a larger pulse width and pulse amplitude. Since the difference current Idiff = Idc_600−Idc_700 flows to the C terminal of the power storage means 2, in the example shown, Idiff> 0, and the power storage means 2 is charged. As can be seen from the above description, since Idiff <0, charging / discharging of the power storage means 2 can be controlled by the differential voltage command Vdiff. This is the same function as the DC / DC converter 100 constituted by the reactor 3, the semiconductor switch elements 4 and 5, and the converter control means 6. Therefore, the current of the DC / DC converter 100 can be reduced by the difference current between the first inverter 600 and the second inverter 700, and the current rating of the semiconductor switch element used in the DC / DC converter is reduced. By doing so, it is possible to reduce the size of the semiconductor switch element, and hence the size of the device.

The power conversion device according to the seventh embodiment is combined with the inverter 200 configured with four semiconductor switch elements according to the first embodiment, or in combination with the inverter 300 configured with six semiconductor switch elements. Even if combined with the three-level inverter 400 according to the third embodiment, or combined with the three-level inverter 500 formed of eight semiconductor switch elements according to the fifth embodiment, the same effect can be obtained. In addition, the same effect can be obtained in an inverter having an output of three or more phases and a single-phase inverter. Furthermore, the same effect can be obtained even with a load other than the motor.
Embodiment 8 FIG.

  FIG. 27 is a circuit configuration diagram showing a main part of the power conversion device according to the eighth embodiment of the present invention. In the eighth embodiment, only the connection form of the DC power source 1 and the power storage means 2 is considered, and therefore the inverter and the motor are omitted in FIG. In the first to seventh embodiments, only the mode in which the negative terminal of the DC power supply 1 and the negative terminal of the power storage means 2 are connected (FIG. 27A) has been described. However, the positive terminal of the DC power supply 1 and the power storage means 2 are described. It is self-evident that the configuration in which the positive terminal is connected (FIG. 27B) is also functionally equivalent.

  Further, although the battery symbol has been used as the power storage means 2, the power storage means 2 may be any power storage device. For example, when the circuit diagram is rewritten using a capacitor, FIGS. )become that way.

  Further, for the purpose of stabilizing the potential or bypassing the PWM ripple current generated by the inverter, a capacitor 70 is connected between the DC power source 1 and the storage means 2 as shown in FIGS. Obviously, even if the DC power source 1 and the power storage means 2 are inserted between terminals that are not directly connected, they are functionally equivalent.

Therefore, even if the connection form of the DC power source 1 and the power storage means 2 is changed as in the eighth embodiment, the effect described in the first to seventh embodiments is not changed, and the size of the power conversion device is increased. It becomes possible to reduce.
Embodiment 9 FIG.

FIG. 28 is a circuit configuration diagram showing a power conversion device according to the ninth embodiment of the present invention. Since the difference between the circuit according to the ninth embodiment and the circuit according to the first embodiment is only the connection point of the W-phase terminal of the motor 7, detailed description of the configuration and operation will be omitted.
In the steady state of the DC / DC converter 100 constituted by the reactor 3, the semiconductor switch elements 4, 5 and the converter control means 6, the average value of the current flowing through the reactor 3 is constant. Therefore, a voltage of 0 is applied to the reactor 3 on average. Therefore, in this state, the average value of the voltage at the positive terminal C of the power storage means 2 and the voltage at the connection point A between the semiconductor switch element 4 and the semiconductor switch element 5 are equal. Therefore, even if the W-phase terminal of the motor 7 is connected not to the positive terminal C of the power storage means 2 but to the connection point A between the semiconductor switch element 4 and the semiconductor switch element 5, the same effect as in the first embodiment is obtained. You can see that

  Therefore, also in the power conversion device according to the ninth embodiment, the voltage at the connection point A between the semiconductor switch element 4 and the semiconductor switch element 5 is set so that the voltage of the power storage means 2 is approximately half the voltage of the DC power supply 1. Is used as it is as the voltage at one terminal of the motor 7, the semiconductor switch elements for one phase can be omitted, and the three-phase motor can be driven by four semiconductor switch elements. Therefore, the number of semiconductor switch elements can be reduced in the entire device, and the size of the device can be reduced.

  The power conversion device according to the ninth embodiment may be combined with the inverter 300 configured with six semiconductor switch elements, or may be combined with the inverter 200 configured with four semiconductor switch elements according to the first embodiment. The same effect can be obtained by combining with the three-level inverter 400 according to the third embodiment or with the three-level inverter 500 including eight semiconductor switch elements according to the fifth embodiment. In addition, the same effect can be obtained in an inverter having an output of three or more phases and a single-phase inverter. Furthermore, the same effect can be obtained even with a load other than the motor.

Also, changing the W-phase terminal of the motor 7 to the connection point A between the semiconductor switch element 4 and the semiconductor switch element 5 instead of the positive terminal C of the power storage means 2 is also effective in the second, fifth, and sixth embodiments. It is self-evident.
Furthermore, even if the connection form of the DC power source 1 and the power storage means 2 is as in the eighth embodiment, the effect does not change.

It is a circuit block diagram which shows the power converter device by Embodiment 1 of this invention. It is a figure explaining operation | movement of the DC / DC converter in the power converter device by Embodiment 1 of this invention. It is a block diagram which shows the structure of the inverter control means in the power converter device by Embodiment 1 of this invention. It is a figure explaining operation | movement of the inverter control means in the power converter device by Embodiment 1 of this invention. It is a figure explaining operation | movement of the inverter in the power converter device by Embodiment 1 of this invention. It is a circuit block diagram which shows the apparatus comprised combining the power converter device by Embodiment 1 of this invention. It is a circuit block diagram which shows the other power converter device by Embodiment 1 of this invention. It is a block diagram which shows the structure of the inverter control means in the power converter device by Embodiment 2 of this invention. It is a figure explaining operation | movement of the inverter in the power converter device by Embodiment 2 of this invention. It is a circuit block diagram which shows the power converter device by Embodiment 3 of this invention. It is a block diagram which shows the structure of the inverter control means in the power converter device by Embodiment 3 of this invention. It is a figure explaining operation | movement of the inverter control means in the power converter device by Embodiment 3 of this invention. It is a figure explaining operation | movement of the inverter in the power converter device by Embodiment 3 of this invention. It is a circuit block diagram which shows the apparatus comprised combining the power converter device by Embodiment 3 of this invention. It is a block diagram which shows the structure of the inverter control means in the power converter device by Embodiment 4 of this invention. It is a figure explaining operation | movement of the inverter in the power converter device by Embodiment 4 of this invention. It is a circuit block diagram which shows the power converter device by Embodiment 5 of this invention. It is a block diagram which shows the structure of the inverter control means in the power converter device by Embodiment 5 of this invention. It is a figure explaining operation | movement of the inverter control means in the power converter device by Embodiment 5 of this invention. It is a figure explaining operation | movement of the inverter in the power converter device by Embodiment 5 of this invention. It is a circuit block diagram which shows the apparatus comprised combining the power converter device by Embodiment 5 of this invention. It is a block diagram which shows the structure of the inverter control means in the power converter device by Embodiment 6 of this invention. It is a figure explaining operation | movement of the inverter in the power converter device by Embodiment 6 of this invention. It is a circuit block diagram which shows the power converter device by Embodiment 7 of this invention. It is a block diagram which shows the structure of the inverter control means in the power converter device by Embodiment 7 of this invention. It is a figure explaining operation | movement of the inverter in the power converter device by Embodiment 7 of this invention. It is a circuit block diagram which shows the principal part of the power converter device by Embodiment 8 of this invention. It is a circuit block diagram which shows the power converter device by Embodiment 9 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 DC power supply, 2 Electric storage means, 3 Reactor, 4, 5, 8-11, 22-25, 28-31, 34-37, 55-66 Semiconductor switch element, 6 Converter control means, 7, 67, 68 Motor, 12, 40, 52, 69 Inverter control means, 13, 14 Subtraction means, 15, 16, 20, 21, 49 to 51 Addition means, 17, 41, 42, 53, 54, 79 Triangular wave generation means, 18, 19, 43-48, 73-78 Comparison means, 26, 27, 32, 33, 38, 39 Diode, 70 Capacitor, 71 Command generation means, 72 Switching means, 100 DC / DC converter, 200, 300, 400, 500, 600 700 Inverter.

Claims (9)

A DC / DC converter in which a DC power source and one terminal are connected to a power storage unit connected to the DC power source and charge / discharge the power storage unit with a voltage of the DC power source, and a plurality of semiconductor switch elements and the semiconductor switch And an inverter that drives a load with the voltage of the DC power supply, wherein the voltage of the power storage means is approximately 1 / of the voltage of the DC power supply. The control signal is generated so that one terminal of the load is connected to the other terminal of the power storage unit and the voltage of the other terminal of the load is controlled based on the voltage of the power storage unit. A power conversion device characterized by that. A DC / DC converter in which a DC power source and one terminal are connected to a power storage unit connected to the DC power source and charge / discharge the power storage unit with a voltage of the DC power source, and a plurality of semiconductor switch elements and the semiconductor switch A power conversion device comprising a three-level inverter configured to drive a load with the voltage of the DC power supply, wherein the voltage of the power storage means is substantially equal to the voltage of the DC power supply. The control signal is generated so that the voltage of the load is controlled to a desired voltage by connecting the other terminal of the power storage means to the neutral point voltage terminal of the three-level inverter. A power conversion device characterized by that. A DC / DC converter in which a DC power source and one terminal are connected to a power storage unit connected to the DC power source and charge / discharge the power storage unit with a voltage of the DC power source, and a plurality of semiconductor switch elements and the semiconductor switch A power conversion device comprising a three-level inverter configured to drive a load with the voltage of the DC power supply, wherein the voltage of the power storage means is substantially equal to the voltage of the DC power supply. And one terminal of the load is connected to the other terminal of the power storage means, the other terminal of the power storage means is connected to the neutral point voltage terminal of the three-level inverter, The power conversion apparatus according to claim 1, wherein the control signal is generated so as to control the voltage at the other terminal of the load with reference to the voltage of the power storage means. The control means generates the control signal so that the voltage at the other terminal of the load is controlled with reference to the voltage of the power storage means and is controlled by a voltage obtained by adding an offset voltage. Or the power converter device of 3. The control means generates the control signal so as to control a voltage of the load to a desired voltage, and generates the control signal so as to control with a voltage obtained by adding an offset voltage. 2. The power conversion device according to 2. A DC power supply and one terminal connected to the storage means connected to the DC power supply, a DC / DC converter that charges and discharges the storage means with the voltage of the DC power supply, and connected to the storage means of the DC power supply A first inverter that drives the first load and is connected between the terminal of the power storage means and a second drive that drives the second load. And a power converter including control means for generating control signals for a plurality of semiconductor switch elements constituting the first inverter and the second inverter, wherein the control means includes the first inverter and the second inverter. A power conversion apparatus characterized by controlling a charge / discharge of the power storage means by adjusting a voltage command of the inverter. A DC power source and one terminal connected to the power storage means connected to the DC power source, and having a series connection body of semiconductor switch elements connected between the DC power source terminals, the voltage of the DC power source A DC / DC converter for charging / discharging the power storage means, a plurality of semiconductor switch elements, and a control means for generating a control signal for the semiconductor switch elements, comprising an inverter for driving a load with the voltage of the DC power supply In the power converter, the voltage of the power storage means is approximately ½ of the voltage of the DC power supply, and one terminal of the load is connected to a connection point of the series connection body of the semiconductor switch elements. The control signal is generated so that the voltage at the other terminal of the load is controlled based on the voltage at the connection point of the series connection body of the semiconductor switch elements. Power conversion equipment. A DC power source and one terminal connected to the power storage means connected to the DC power source, and having a series connection body of semiconductor switch elements connected between the DC power source terminals, the voltage of the DC power source A DC / DC converter for charging / discharging the storage means, and a plurality of semiconductor switch elements and a control means for generating a control signal for the semiconductor switch elements, and a three-level inverter for driving a load with the voltage of the DC power supply The power conversion device is provided, wherein the voltage of the power storage means is approximately ½ of the voltage of the DC power supply, and one terminal of the load is connected to a connection point of the series connection body of the semiconductor switch elements. Connect the other terminal of the power storage means to the neutral point voltage terminal of the three-level inverter, and connect the voltage of the other terminal of the load to the series connection body of the semiconductor switch elements. Power conversion device is characterized in that so as to generate the control signal to control the reference voltage of the connection point. The control means controls the voltage at the other terminal of the load based on the voltage at the connection point of the series connection body of the semiconductor switch elements, and generates the control signal so as to be controlled by a voltage obtained by adding an offset voltage. The power converter according to claim 7 or 8, wherein

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