JP5915753B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device capable of supplying a stable voltage to a load even when a voltage fluctuation of an AC power supply or a power failure of the AC power supply occurs.

FIG. 10 is a diagram for explaining a power converter of a constant inverter feeding method disclosed in Patent Document 1. In FIG. This power converter once converts the voltage of the AC power source into a DC voltage, converts the DC voltage into an AC voltage again, and supplies it to the load.
In the figure, 1 is a single-phase AC power source, 2 is a capacitor, 3 is a converter circuit, 41 is an inverter circuit, 5 is a filter circuit, and 6 is a load.

  Converter circuit 3 includes a series circuit of switching elements Qp and Qn, a series circuit of capacitors Cp and Cn connected in parallel to the series circuit, and a reactor L. Reactor L is connected between the connection point of switching elements Qp and Qn and one end of AC power supply 1.

  The inverter circuit 41 includes a switching element series circuit and a first bidirectional switch. The switching element series circuit is a circuit formed by connecting switching elements Q1 and Q2 in series. The first bidirectional switch is a circuit formed by connecting switch elements S1 and S2 in antiparallel. The switching element series circuit is connected between the DC output terminals of the converter circuit 3. The bidirectional switch is connected between one end of the AC power source 1 and the series connection point of the switching elements Q1, Q2.

The filter circuit 5 is configured by connecting a reactor Lf1 and a capacitor Cf1 in series. One end of reactor Lf1 is connected to the midpoint of connection of switching elements Q1, Q2. One end of the capacitor Cf1 is connected to a connection midpoint of the capacitor series circuit.
The load 6 is connected between a connection point between the reactor Lf1 and the capacitor Cf1 and the other end of the AC power supply 1.

In the above configuration, the converter circuit 3 rectifies the voltage of the AC power supply 1 by turning on and off the switching elements Qp and Qn. The capacitors Cp and Cn are charged to a predetermined voltage by the rectified voltage. Capacitors Cp and Cn charged to a predetermined voltage each form a DC power source.
The inverter circuit 41 turns on and off the switching elements Q1 and Q2, and converts the voltage of the DC power source composed of the capacitors Cp and Cn into the AC voltage Vu. Further, the inverter circuit 41 turns on and off the switch elements S1 and S2 to convert the voltage of the AC power supply 1 into the AC voltage Vu. The AC voltage Vu output from the inverter circuit 41 includes a high frequency component.
The filter circuit 5 removes a high frequency component included in the AC output voltage and outputs a voltage Vload that is a fundamental wave component of the output voltage Vu. An AC voltage Vload is supplied to the load 6.

  Next, FIG. 11 shows a power conversion device in which a second bidirectional switch is further added to the inverter circuit 41 of the power conversion device shown in FIG. The second bidirectional switch is a circuit formed by connecting switch elements S3 and S4 in antiparallel. This circuit is connected between the connection point of switching elements Q1, Q2 and the connection point of capacitors Cp, Cn.

In addition to the operation of the power conversion device shown in FIG. 10, this power conversion device can output a zero voltage by turning on or off the switch element S3 or S4. The zero voltage is the potential at the connection point of the capacitors Cp and Cn. With this operation, the power conversion device can supply a predetermined AC voltage to the load even when the voltage of the AC power supply 1 fluctuates or a power failure occurs.
For example, the power conversion device having the above configuration outputs a predetermined AC voltage by performing a boosting operation when the voltage Vr of the AC power supply 1 decreases. FIG. 12 is a diagram illustrating the voltage Vu output from the power conversion device and the voltage Vload applied to the load 6 when the voltage Vr of the AC power supply 1 decreases.

  When the positive half wave of the AC voltage Vu is output in the step-up operation, the power conversion device alternately turns on and off the switching element Q1 and the switching element S1. By this operation, a voltage obtained by adding the voltage Vp of the capacitor Cp to the voltage of the AC power supply 1 is output. Further, when outputting the negative half wave of the AC voltage Vu, the power conversion device alternately turns on and off the switching element Q2 and the switching element S2. By this operation, a voltage obtained by adding the voltage Vn of the capacitor Cn to the voltage of the AC power supply 1 is output.

  In addition, when the voltage Vr of the AC power supply 1 rises, this power conversion device outputs a predetermined AC voltage by performing a step-down operation. In the step-down operation, when the positive half wave of the AC voltage Vu is output, the switch elements S1 and S3 are alternately turned on and off. Further, when outputting the negative half wave of the AC voltage Vu, the power conversion device alternately turns on and off the switch elements S2 and S4.

  Further, when the AC power supply 1 fails, this power conversion device outputs a predetermined AC voltage by performing a backup operation. When the positive half wave of AC voltage Vu is output in the backup operation, this power converter turns on and off switching elements Q1 and Q2 alternately. The power converter can also output the positive half wave of the AC voltage Vu by alternately turning on and off the switching element Q1 and the switching element S3. Moreover, when outputting the negative half wave of AC voltage Vu, this power converter turns on and off switching elements Q1 and Q2 alternately. The power converter can also output the negative half wave of the AC voltage Vu by alternately turning on and off the switching element Q2 and the switching element S4. FIG. 13 is a diagram illustrating an example of the voltage Vu output from the power converter and the voltage Vload applied to the load 6 during the backup operation.

  Further, when performing this direct transmission operation, the power conversion device turns on the switch elements S1 and S2 and outputs the voltage of the AC power supply 1.

  The harmonic component contained in the output voltage Vu is removed by the filter circuit 5. Therefore, the filter circuit 5 outputs a voltage Vload that is a fundamental wave component of the output voltage Vu.

Japanese Patent Laid-Open No. 10-075581 International Publication WO2012 / 067167A1

  The above power converter must limit the maximum value of the output current within a range of current that can be controlled by the switching element and the switching element. This output current is a current obtained by adding a ripple current to the fundamental wave current.

  On the other hand, this power conversion device turns on and off switching elements Q1 and Q2 at the same frequency in the step-up operation and the backup operation. The change width of the voltage applied to the reactor Lf1 is maximized when the AC voltage is output using only the voltage of the DC power source as in the backup operation. Therefore, the ripple current flowing through reactor Lf1 is maximized during the backup operation. That is, the current controlled by switching elements Q1 and Q2 is maximized during the backup operation. Therefore, the inductance value of reactor Lf1 is generally determined so that the ripple current becomes a predetermined value under the conditions during the backup operation.

  However, the inductance value of reactor Lf1 determined in this way is a larger value than the inductance value required during the boosting operation. In order to increase the inductance value of the reactor Lf1, it is necessary to increase the number of turns of the coil. When the number of turns of the coil is increased, the conductor resistance of the coil is increased and the copper loss of the reactor Lf1 is increased. As a result, there arises a problem that the efficiency of the power converter decreases. Moreover, there exists a problem that a power converter device enlarges with the reactor Lf1 becoming large.

  The present invention has been made to solve such problems of the prior art. That is, the object of the present invention is to increase the maximum value of the inverter output current in the operation mode in which the AC voltage is output using only the voltage of the DC power supply without increasing the inductance value of the reactor Lf1, during the step-up operation and the step-down operation. It is an object of the present invention to provide a power converter that can be made substantially the same as or smaller than the maximum value of the inverter output current.

  In order to achieve the above object, the present invention has one end connected to the voltage of a DC power supply series circuit formed by connecting the first and second DC power supplies in series and the connection point of the first and second DC power supplies. It is applied to a power converter provided with an inverter that outputs a predetermined AC voltage using a voltage of an AC power source.

  This inverter has a switching element series circuit, a first bidirectional switch, and a reactor. The switching element series circuit is formed by connecting first and second switching elements in series, and is connected to both ends of the DC power supply series circuit. One end of the first bidirectional switch is connected to a connection point between the first and second switching elements, and the other end is connected to the other end of the AC power supply. The reactor is connected between the connection point of the first and second switching elements and the load.

  And this electric power converter is at least 1st control mode, 2nd control mode, and 3rd control mode among 1st control mode, 2nd control mode, and 3rd control mode. The inverter is operated in two or more control modes including. The first control mode is a control mode in which a predetermined AC voltage higher than the voltage of the AC power supply is generated using the voltage of the AC power supply and the voltage of the DC power supply series circuit. The second control mode is a control mode for generating a predetermined AC voltage lower than the voltage of the AC power supply by using at least the voltage of the AC power supply among the voltage of the AC power supply and the voltage of the DC power supply series circuit. The third control mode is a control mode in which a predetermined AC voltage is generated using the voltage of the DC power supply series circuit.

  Further, in this power conversion device, the frequency at which the first and second switching elements are turned on / off is the first frequency in the first control mode and the second frequency in the second control mode. In the power converter, in the third control mode, the frequency for turning on and off the first and second switching elements is set to a third frequency higher than the first and second frequencies. It is said.

  The inverter of the power converter further includes a second bidirectional switch connected between the connection point of the first and second switching elements and the connection point of the first and second DC power supplies. It can also be taken.

  In this power converter, the voltages of the first and second DC power supplies are voltages generated using the voltage of the AC power supply and are larger than the amplitude value of the voltage of the AC power supply. it can.

  The power conversion device according to the present invention, when the inverter operates in either the first control mode or the second control mode and the third control mode, sets the third frequency as follows: Can be determined.

  First, the power converter is configured such that the maximum value of the inverter output current in the third control mode is substantially the same as the maximum value of the current output by the inverter in the first or second control mode, or The third frequency can be determined to be smaller than the maximum value.

  Alternatively, in the power conversion device, the ripple current included in the inverter output current in the third control mode near the phase where the fundamental wave of the inverter output current becomes maximum is the first or second near the phase. The third frequency can be determined so as to be substantially the same as the ripple current included in the inverter output current in the control mode or smaller than the ripple current.

  Alternatively, the power conversion device can change the voltage change width applied to the reactor in the third control mode in the vicinity of the phase where the fundamental wave of the inverter output current becomes maximum, and the first or second control in the vicinity of the phase. The third frequency so that the coefficient obtained by dividing the voltage change applied to the reactor in the mode is substantially the same as the frequency obtained by multiplying the first frequency, or is larger than this frequency. Can be determined.

  Alternatively, in the power converter, in the vicinity of the phase where the fundamental wave of the inverter output current is maximum, the difference between the voltage time products of the two levels of voltages applied to the reactor in the third control mode is The first and second control modes in the vicinity are substantially equal to or smaller than the difference between the voltage and time products of the two levels of voltages applied to the reactor in the first or second control mode. Three frequencies can be defined.

Moreover, the power converter device which concerns on this invention can determine a 3rd frequency as follows, when an inverter operate | moves having a 1st, 2nd and 3rd control mode.
First, in the power converter, the maximum value of the inverter output current in the third control mode is approximately the same as the maximum value of any one of the inverter output currents in the first and second control modes. Alternatively, the third frequency can be determined to be smaller than this maximum value.

  Alternatively, in the power conversion device, the ripple current included in the inverter output current in the third control mode near the phase where the fundamental wave of the inverter output current becomes maximum is the first and second in the vicinity of the phase. The third frequency can be determined so as to be substantially the same as the ripple current included in any of the inverter output currents in the control mode, or to be smaller than the ripple current.

  Alternatively, the power conversion device can provide a voltage change width applied to the reactor in the third control mode in the vicinity of the phase where the fundamental wave of the inverter output current is maximum, and the first and second controls in the vicinity of the phase. The coefficient obtained by dividing by one of the voltage change widths applied to the reactor in the mode is substantially the same as the frequency obtained by multiplying the first frequency, or is larger than this frequency. Three frequencies can be defined.

  Alternatively, in the power converter, in the vicinity of the phase where the fundamental wave of the inverter output current is maximum, the difference between the voltage time products of the two levels of voltages applied to the reactor in the third control mode is To be substantially the same as or smaller than the difference between the voltage time products of the two levels of voltages applied to the reactor in the vicinity in the first and second control modes. The third frequency can be determined.

  According to the present invention, the maximum value of the inverter output current in the operation mode in which the AC voltage is output using only the voltage of the DC power supply without increasing the inductance value of the reactor is set as the inverter output during the boosting operation and the bucking operation. It can be made to be substantially the same as the maximum value of the current or smaller than these maximum values.

It is a figure for demonstrating the circuit structure of the power converter device which concerns on 1st Embodiment to which this invention is applied. It is a figure for demonstrating operation | movement of an inverter circuit. It is a figure for demonstrating operation | movement of a pressure | voltage rise mode. It is a figure for demonstrating operation | movement of backup mode. It is a figure for demonstrating switching of a carrier signal. It is a figure for demonstrating the circuit structure of the power converter device which concerns on 2nd Embodiment to which this invention is applied. It is a figure for demonstrating operation | movement of an inverter circuit. It is a figure for demonstrating operation | movement of a pressure | voltage rise mode. It is a figure for demonstrating operation | movement of backup mode. It is a figure for demonstrating the structure of the power converter device which concerns on a prior art. It is a figure for demonstrating the other structure of the power converter device which concerns on a prior art. It is a figure for demonstrating the pressure | voltage rise mode of the power converter device which concerns on a prior art. It is a figure for demonstrating the backup mode of the power converter device which concerns on a prior art.

1st Embodiment of the power converter device to which this invention is applied is described using FIGS.
FIG. 1 is a diagram for explaining a circuit configuration of the power conversion device according to the first embodiment. In the figure, 1 is an AC power supply, 2 is a capacitor, 30 is a DC power supply series circuit, 41 is an inverter circuit, 5 is a filter circuit, 6 is a load, and 100 is a control circuit.

  The AC power source 1 is a single-phase AC power source having a terminal R and a terminal S. A capacitor 2 is connected between the terminal R and the terminal S of the AC power supply 1.

The DC power supply series circuit 30 is a DC power supply formed by connecting a positive DC power supply Psp (first DC power supply) and a negative DC power supply Psn (second DC power supply) in series. A connection point between the DC power supply Psp and the DC power supply Psn is a neutral point terminal O. The neutral point terminal O is a terminal that outputs an intermediate potential of the DC power supply series circuit 30. The power supply terminal S of the AC power supply 1 is connected to the neutral point terminal O.
The DC power supply series circuit 30 can be configured by, for example, the converter circuit 3 shown in FIG. In addition, the DC power supply series circuit 30 may be a circuit configured by another method as long as a three-level potential including an intermediate potential can be output using the voltage of the AC power supply 1.

The inverter circuit 41 includes a switching element series circuit and a first bidirectional switch.
The switching element series circuit is a circuit in which switching elements Q1 and Q2 are connected in series. This switching element series circuit is connected between the positive terminal P and the negative terminal N of the DC power supply series circuit 30. A series connection point of the switching elements Q1, Q2 is connected to an AC output terminal U (first AC output terminal). The AC output terminal V (second AC output terminal) is connected to the neutral point terminal O.
The first bidirectional switch is a circuit in which switch elements S1 and S2 are connected in antiparallel. The first bidirectional switch is connected between the AC output terminal U and the power supply terminal R. Specifically, the collector terminal side of the switch element S1 is connected to the power supply terminal R. The emitter terminal side of the switch element S1 is connected to the AC output terminal U.

  The AC output terminals U and V are connected to the load 6 through the filter circuit 5. The filter circuit 5 is constituted by a series circuit of a reactor Lf1 and a capacitor Cf1. The load 6 is connected to both ends of the capacitor Cf1.

  Here, the switching elements Q1 and Q2 are IGBTs (Insulated Gate Bipolar Transistors) in which diodes are connected in antiparallel. However, the switching elements Q1 and Q2 are not limited to the elements configured as described above. The switching elements Q1 and Q2 may be configured using other semiconductor elements such as MOSFET (Metal Oxide Semiconductor Field Effect Transistor) that can be turned on and off at a frequency several tens of times higher than the frequency of the AC power supply 1. .

  The bidirectional switch can pass a current in one direction by turning on one of the switch elements. In addition, the bidirectional switch can flow current in the other direction by turning on the other switch element. Note that the bidirectional switch may have another configuration as long as such a function can be exhibited.

  In the power converter, the positive terminal P of the DC power supply series circuit 30 outputs the positive potential of the DC power supply Psp (hereinafter referred to as the positive voltage Vp). The negative terminal N of the DC power supply series circuit 30 outputs a negative potential (hereinafter referred to as a negative voltage Vn) of the DC power supply Psn. The power supply terminal R of the AC power supply 1 outputs the voltage Vr of the AC power supply 1.

  The inverter circuit 41 is referred to as “between the AC output terminals U and V” or “between the AC output terminals U and V” by passing a current through the switching element Q1. ) To output a positive voltage Vp. Further, the inverter circuit 41 outputs a negative voltage Vn between the AC output terminals U-V by causing a current to flow through the switching element Q2. Further, the inverter circuit 41 outputs the voltage Vr of the AC power supply between the AC output terminals U-V by causing a current to flow through one of the switch elements S1 and S2. The inverter circuit 41 outputs a single-phase AC voltage Vu between the AC output terminals U-V by controlling the on / off operation of the switching elements Q1, Q2 and the switch elements S1, S2.

Here, the power converter according to the present embodiment includes at least first, second, and third control modes.
The first control mode is a mode in which a predetermined AC voltage Vu higher than the AC voltage Vr is output using the voltage Vr of the AC power supply 1 and the voltages Vp and Vn of the DC power supply series circuit 30. This first control mode is generally referred to as a boost mode. In the boost mode, when the voltage of the AC power supply 1 drops below a predetermined value, the voltages Vp and Vn of the DC power supply series circuit 30 are superimposed on the voltage Vr of the AC power supply, and the output voltage Vu is maintained at the predetermined voltage.

The second control mode is a mode for outputting a predetermined AC voltage Vu lower than the AC voltage Vr by using at least the AC voltage Vr among the voltage Vr of the AC power source 1 and the voltages Vp and Vn of the DC power source series circuit 30. is there. This second control mode is generally referred to as a step-down mode.
That is, the first and second control modes are voltage compensation modes for maintaining the output at the predetermined voltage Vu when the voltage Vr of the AC power supply 1 fluctuates.

  The third control mode is a mode in which a predetermined AC voltage Vu is output using the voltages Vp and Vn of the DC power supply series circuit 30. When the AC power supply 1 fails, the power converter operates in a backup mode that is one of the third control modes. Note that the third control mode includes a mode in which a predetermined AC voltage Vu is output using the voltages Vp and Vn of the DC power supply series circuit 30 while the AC power supply 1 is in a healthy state.

  The power converter according to the present embodiment also includes a direct transmission mode that outputs the voltage Vr of the AC power supply 1 as it is. However, since this mode is not related to the present invention, its description is omitted.

  In the present embodiment, the operation of turning on / off the switching elements Q1, Q2 and the switching elements S1, S2 in each control mode is performed for each control period. This control period is a period corresponding to the frequency at which each element is turned on and off.

Moreover, the power converter device which concerns on this embodiment defines the 1st and 2nd element in each control period. The first and second elements are elements previously selected from the switching elements Q1 and Q2 and the switch elements S1 and S2 based on each control mode and its operating conditions. The first and second elements are alternately turned on and off in each control period. When the first element is turned on, the first voltage is output between the AC output terminals U-V. Further, when the second element is turned on, a second voltage is output between the AC output terminals U-V. In each control period, the voltage Vu composed of the two-level voltage is a voltage corresponding to the AC voltage command Vu ^* .

  The inverter circuit 41 alternately turns on and off the first and second elements at the first frequency in the first control mode. The first frequency is determined based on the maximum current Im that can be controlled by the switching elements Q1 and Q2 and the switching elements S1 and S2 and the inductance value of the reactor Lf1. Hereinafter, the maximum current that can be controlled by these elements is referred to as a controllable current Im.

The inverter circuit 41 alternately turns on and off the first and second elements at the second frequency in the second control mode. The second frequency is determined based on the controllable current Im and the inductance value of the reactor Lf1.
If the maximum value of the output current Iu is smaller than the controllable current Im, the first and second frequencies may be the same frequency or different frequencies.

In the third control mode, the inverter circuit 41 turns on and off the first and second elements alternately at the third frequency. In each control period, the change width of the first and second voltages is maximized in the third control mode. Therefore, when the third frequency is made the same as the higher one of the first and second frequencies, the ripple current of the output current Iu is maximized in the third control mode.
Therefore, the third frequency is set to a frequency that is a predetermined multiple higher than the higher one of the first and second frequencies. In this way, the maximum value of the output current Iu in the third control mode is substantially the same as or smaller than the maximum value of the output current Iu in the first and second control modes. can do.

  Hereinafter, the present invention will be described using operations of the power conversion device in the boost mode (first control mode) and the backup mode (third control mode). The relationship between the operations of the power conversion device in the step-down mode (second control mode) and in the third control mode can be considered in the same way.

First, the operation of the inverter circuit 41 in the boost mode will be described with reference to FIGS.
FIG. 2 is a diagram for explaining control signals of switching elements Q1, Q2 and switching elements S1, S2 when inverter circuit 41 operates in the boost mode. The control circuit 100 generates a control signal for each element from the relationship between the AC voltage command Vu ^* and the voltage Vr of the AC power supply 1 in each control period belonging to the boost mode.

In the figure, the “Relationship between Vr and Vu ^* ” column shows conditions for determining the region shown in the “δ (region)” column. The “δ (region)” column indicates a region determined under the condition of the “Relationship between Vr and Vu ^* ” column. The column “α (pulse width command)” shows an equation for calculating a pulse width command α of the first element described later. The “control signal” column shows the states of the control signals G1, G2 and Gs1, Gs2 of the switching elements Q1, Q2 and the switching elements S1, S2.

The power conversion device determines a region as follows and determines the states of the control signals G1, G2 and Gs1, Gs2 of each element.
When the relationship between the AC voltage command Vu ^* and the voltage Vr is Vu ^* > Vr, the control period is set as the region 11. The region 11 is a region for the inverter circuit 41 to output the positive half wave of the voltage Vu.
Further, when the relationship between the AC voltage command Vu ^* and the voltage Vr is Vu ^* ≦ Vr, the control period is set as the region 12. The region 12 is a region for the inverter circuit 41 to output the negative half wave of the voltage Vu.

  The pulse width command α in the regions 11 and 12 is calculated using the following equations (1) and (2).

  In each of the regions 11 and 12, the element selected as the first element and the element selected as the second element are determined in advance. In addition, elements to be on-arm elements or off-arm elements are also determined in advance.

  In FIG. 2, “Hon” indicates a control signal of the element selected as the first element. “Lon” indicates a control signal of the element selected as the second element. The control signal “Lon” is a signal obtained by inverting the high level and the low level of the control signal “Hon”. “H” indicates a control signal of the element selected as the on-arm element. “L” indicates a control signal of the element selected as the off-arm element. When each signal is at a high level, the corresponding element is turned on. When each signal is at a low level, the corresponding element is turned off.

  When the control period is the region 11, the switching element Q1 is selected as the first element, and the switch element S2 is selected as the second element. Further, the switch element S1 is selected as an on-arm element, and the switching element Q2 is selected as an off-arm element. Therefore, the control signal G1 in the region 11 is “Hon”, and the control signal Gs2 is “Lon”. Further, the control signal Gs1 becomes “H” and the control signal G2 becomes “L”.

  When the control period is the region 12, the switching element Q2 is selected as the first element, and the switch element S1 is selected as the second element. Further, the switch element S2 is selected as an on-arm element, and the switching element Q1 is selected as an off-arm element. Therefore, the control signal G2 in the region 12 is “Hon”, and the control signal Gs1 is “Lon”. Further, the control signal Gs2 becomes “H” and the control signal G1 becomes “L”.

  Next, the operation when the inverter circuit 41 outputs the positive half wave of the voltage Vu in the region 11 will be described with reference to FIG. Note that the operation when the inverter circuit 41 outputs the negative half wave of the voltage Vu in the region 12 can be considered in the same manner as the operation in the region 11, and the description thereof is omitted.

  In the region 11, the switching element Q1 and the switching element S2 are alternately turned on / off. A frequency at which the switching element Q1 and the switching element S2 are turned on and off is a frequency f1A (first frequency). Further, the period of the frequency f1A is T1A.

FIG. 3A shows the control signal “Hon” of the first element when the control period is the region 11. The control signal “Hon” is a signal that is turned on for a time T1AH and then turned off for a time T1AL in the control period T1A. The time T1AH is a time corresponding to the pulse width command α calculated by the above equation (1). For example, the time T1AH can be obtained by multiplying the cycle T1A of the control period by the pulse width command α.
3B to 3E show the on / off states of the switching elements Q1 and Q2 and the switching elements S1 and S2, respectively. The hatched portions in FIG. 3B and FIG. 3D indicate the period during which the current Iu flows in the element. When the switching element Q1 and the switching element S2 are alternately turned on / off, there is a rest period in which both elements are turned off at the same time. However, in order to simplify the explanation, the rest period is omitted in FIG.

During the control period, the voltage Vu shown in FIG. 3F is output between the AC output terminals U-V. The voltage Vu becomes a positive voltage Vp during the time T1AH from the start point of the control period T1A, and then becomes the voltage Vr of the AC power supply 1 during the time T1AL. During the control period, the average value of the voltage Vu output between the AC output terminals U-V is equal to the AC voltage command Vu ^* .

  In addition, the inverter circuit 41 outputs a current Iu shown in FIG. The current Iu flows through the path R1AH of the neutral point terminal O of the positive side terminal P of the DC power supply series circuit 30 → the switching element Q1 → the filter circuit 5 and the load 6 → DC power supply series circuit 30 for the time T1AH. At this time, the current Iu gradually increases. Current Iu flows through path R1AL of filter circuit 5 and load 6 → AC power supply 1 → switch element S1 → filter circuit 5 and load 6 for time T1AL. At this time, the current Iu gradually decreases.

By performing the above operation in each control period, the power converter can output the AC voltage Vu corresponding to the AC voltage command Vu ^* and supply power to the load.

Here, the current Iu flows through the reactor Lf1 as described above. The difference between the maximum value and the minimum value of the current Iu is the ripple current Ir1A. The maximum value of the ripple current Ir1A is determined such that the current Iu is smaller than the controllable current Im.
The ripple current Ir1A is determined by the inductance value of the reactor Lf1, the voltages Vp and Vr applied to the reactor Lf1, and the respective application times T1AH and T1AL. The application time of the voltage applied to the reactor Lf1 corresponds to the frequency f1A at which the switching element Q1 and the switching element S2 are turned on / off.

Next, the operation of the inverter circuit 41 when the positive half wave of the voltage Vu is output in the backup mode will be described with reference to FIG. Note that the operation when the inverter circuit 41 outputs the negative half wave of the voltage Vu can be considered in the same manner as the operation of outputting the positive half wave, and the description thereof is omitted.
In the backup mode, the switching elements Q1, Q2 are alternately turned on / off. A frequency at which the switching elements Q1, Q2 are turned on / off is a frequency f1B (third frequency). The period of the frequency f1B is assumed to be T1B.

  FIG. 4A shows the control signal “Hon” of the first element in the control period in which the positive half wave of the voltage Vu is output. The control signal “Hon” is a signal that is turned on for a time T1BH and then turned off for a time T1BL in the control period T1B. The time T1BH is a time corresponding to a pulse width command α calculated by equation (3) described later. For example, the time T1BH can be obtained by multiplying the cycle T1B of the control period by the pulse width command α.

FIGS. 4B to 4E show the on / off states of the switching elements Q1 and Q2 and the switching elements S1 and S2, respectively. The switching element Q1 performs an on / off operation in synchronization with the control signal Hon in the control period T1B. The switching element Q2 and the switch elements S1 and S2 remain off.
In FIG. 4B and FIG. 4D, the hatched portion indicates a period during which the current Iu flows in the element.

  In the backup mode, the pulse width command α when the positive half wave and the negative half wave of the voltage Vu are output is calculated using the following equations (3) and (4).

During the control period, the voltage Vu shown in FIG. 4F is output between the AC output terminals U-V. The voltage Vu becomes a positive voltage Vp during the time T1BH from the start point of the control period, and then becomes a negative voltage Vn during the time T1BL. During the control period, the average value of the voltage Vu output between the AC output terminals U-V is equal to the AC voltage command Vu ^* .

  Further, the inverter circuit 41 outputs a current Iu shown in FIG. The current Iu flows through the path R1BH of the neutral point terminal O of the positive side terminal P of the DC power supply series circuit 30 → the switching element Q1 → the filter circuit 5 and the load 6 → DC power supply series circuit 30 for the time T1BH. At this time, the current Iu gradually increases. Current Iu flows through path R1BL of filter circuit 5 and load 6 → DC power supply Psn → diode of switching element Q2 → filter circuit 5 and load 6 during time T1BL. At this time, the current Iu gradually decreases. The difference between the maximum value and the minimum value of the current Iu is the ripple current Ir1B.

By performing the above operation in each control period, the power conversion device can output the AC voltage Vu corresponding to the AC voltage command Vu ^* even if the AC power supply 1 fails.

Here, an increase in the ripple current Ir1B that occurs near the phase where the fundamental wave of the current Iu is maximum is suppressed. The ripple current Ir1B is set to be substantially the same as the ripple current Ir1A generated in the vicinity of the same phase in the boost mode. Then, the maximum value of current Iu in the backup mode can be made substantially the same as the maximum value of current Iu in the boost mode.
Therefore, the frequency f1B is set to a frequency higher than the frequency f1A.
For example, the frequency f1B is set according to the ratio of the voltage change width in the control period in the backup mode and the boost mode. In this case, the frequency f1B is calculated by the following equation (5).

  If the frequency f1B is set in this way, the time T1BH is shortened in inverse proportion to the frequency f1B, so that an increase in the ripple current Ir1B can be suppressed. Therefore, the frequency f1B may be set so that the ripple current Ir1B is substantially the same as the ripple current Ir1A.

  Further, in the vicinity of the phase where the fundamental wave of the current Iu becomes maximum, the difference between the voltage time product applied to the reactor Lf1 at each of the times T1BH and T1BL in the backup mode and the reactor at each of the times T1AH and T1AL in the boost mode. The difference between the voltage time products applied to Lf1 may be substantially the same. For example, the frequency f1B is set so as to satisfy the following expression (6).

If the frequency f1B is set so as to satisfy Expression (6), the difference between the voltage and time products applied to the reactor Lf1 in the backup mode becomes substantially the same as the difference between the voltage and time products applied in the boost mode. Therefore, an increase in the ripple current Ir1B is suppressed, and the ripple current Ir1B becomes substantially the same as the ripple current Ir1A.
Further, if the temperature rise of switching elements Q1, Q2 and switching elements S1, S2 and reactor Lf1 is allowed, frequency f1B can be set to a frequency higher than the above frequency. In this case, the ripple current Ir1B can be made smaller than the ripple current Ir1A without increasing the inductance value of the reactor Lf1.
Further, the frequency f1B may be set so that the total loss generated in the switching elements Q1, Q2 and switching elements S1, S2 and the reactor Lf1 in the backup mode is minimized.

  In this way, the maximum value of the current Iu in the backup mode can be made substantially equal to or smaller than the maximum value of the current Iu in the boost mode without increasing the inductance value of the reactor Lf1. it can. Moreover, since it is not necessary to increase the number of turns of the coil of reactor Lf1, the enlargement of reactor Lf1 can be suppressed. Furthermore, since it is not necessary to increase the number of turns of the coil of the reactor Lf1, it is possible to suppress an increase in the copper loss of the reactor Lf1.

FIG. 5 is a diagram for explaining an operation of switching the carrier signal Sc when the AC power supply 1 is momentarily interrupted. Here, the carrier signal Sc is indicated by a triangular wave.
When the inverter circuit 41 is operating in the first control mode, the frequency of the carrier signal Sc is the frequency f1A. When the AC power supply 1 fails, the operation of the inverter circuit 41 is switched to the backup mode (third control mode). At this time, the frequency of the carrier signal Sc is switched to the frequency f1B. Thereafter, when the AC power source 1 recovers, the operation of the inverter circuit 41 returns to the first control mode. At this time, the frequency of the carrier signal Sc becomes the frequency f1A again.

Switching of the carrier signal Sc is performed at a valley point of the carrier signal. Thereby, the continuity and symmetry of the carrier signal Sc are maintained.
Usually, the power failure of the AC power supply 1 recovers in a short time. Therefore, even if the inverter circuit 41 operates at the frequency f1B during this time, the temperature rise due to the increase in generated loss does not cause a problem.

  When the power converter outputs the positive half wave of the voltage Vu in the second control mode, the switch element S1 is selected as the first element and the switch element S2 is selected as the second element. Further, when the power conversion device outputs the negative half wave of the voltage Vu in the second control mode, the switch element S2 is selected as the first element, and the switch element S1 is selected as the second element. In either case, the switching elements Q1, Q2 are off.

  The setting of the third frequency when the power conversion device operates in the second control mode and the third control mode is considered in the same manner as in the case of operating in the first control mode and the third control mode described above. be able to. By setting the third frequency, the maximum value of the current Iu in the third control mode is substantially the same as the maximum value of the current Iu in the second control mode without increasing the inductance value of the reactor Lf1, or A smaller current can be obtained.

  Further, when the power conversion device operates in the first, second, and third control modes, the third frequency is set in the same way as described above. By setting the third frequency, the maximum value of the current Iu in the third control mode is substantially equal to the maximum value of the current Iu in the first and second control modes without increasing the inductance value of the reactor Lf1. The current can be the same or less.

  Moreover, since it is not necessary to increase the number of turns of the coil of reactor Lf1, the enlargement of reactor Lf1 can be suppressed. Furthermore, since it is not necessary to increase the number of turns of the coil of the reactor Lf1, it is possible to suppress an increase in the copper loss of the reactor Lf1.

Next, 2nd Embodiment of the power converter device to which this invention is applied is described using FIGS.
FIG. 6 is a diagram for explaining a circuit configuration of the power conversion device according to the second embodiment. In the figure, 1 is an AC power supply, 2 is a capacitor, 30 is a DC power supply series circuit, 42 is an inverter circuit, 5 is a filter circuit, 6 is a load, and 101 is a control circuit. The same components as those in the first embodiment shown in FIG. The description of the components having the same reference numerals is omitted.

The feature of this embodiment is that the inverter circuit 42 includes a second bidirectional switch in addition to the configuration of the inverter circuit 41. The second bidirectional switch is a circuit formed by connecting the switch element S3 and the switch element S4 in antiparallel.
In the second bidirectional switch, the collector side of the switch element S3 is connected to the neutral point terminal O. The emitter side of the switch element S3 is connected to the AC output terminal U. Therefore, when a current flows through one of the switch elements S3 and S4, the voltage at the neutral point terminal O (zero voltage Vz) is output to the AC output terminal U.

The inverter circuit 42 outputs a single-phase AC voltage Vu between the AC output terminals U-V, using four levels of voltages, that is, a positive voltage Vp, a negative voltage Vn, an AC voltage Vr, and a zero voltage Vz. The AC voltage Vu is a voltage corresponding to the AC voltage command Vu ^* .
Here, the power conversion device according to the present embodiment includes at least first, second, and third control modes, similarly to the power conversion device according to the first embodiment. The functions of the first, second, and third control modes are the same as the functions described in the first embodiment. Therefore, description of the functions of these modes is omitted.

In the present embodiment, the operation of turning on and off the switching elements Q1 and Q2 and the switching elements S1 to S4 in each control mode is performed for each control period. This control period is a period corresponding to the frequency at which each element is turned on and off.
Moreover, the power converter device which concerns on this embodiment defines the 1st and 2nd element in each control period. The first and second elements are elements previously selected from the switching elements Q1 and Q2 and the switch elements S1 to S4 based on each control mode and its operating conditions. The first and second elements are alternately turned on and off in each control period. When the first element is turned on, the first voltage is output between the AC output terminals U-V. Further, when the second element is turned on, a second voltage is output between the AC output terminals U-V. In each control period, the voltage Vu composed of the two-level voltage is a voltage corresponding to the AC voltage command Vu ^* .

The inverter circuit 42 alternately turns on and off the first and second elements at the first frequency in the first control mode. The first frequency is determined based on the controllable current Im that can be controlled by the switching elements Q1 and Q2 and the switching elements S1 to S4 and the inductance value of the reactor Lf1.
In the second control mode, the inverter circuit 42 alternately turns on and off the first and second elements at the second frequency. The second frequency is determined based on the controllable current Im and the inductance value of the reactor Lf1.
If the maximum value of the output current Iu is smaller than the controllable current Im, the first and second frequencies may be the same frequency or different frequencies.

The inverter circuit 42 alternately turns on and off the first and second elements at the third frequency in the third control mode. In each control period, the change width of the first and second voltages is maximized in the third control mode. Therefore, when the third frequency is made the same as the higher one of the first and second frequencies, the ripple current of the output current Iu is maximized in the third control mode.
Therefore, the third frequency is set to a frequency that is a predetermined multiple higher than the higher one of the first and second frequencies. In this way, the maximum value of the output current Iu in the third control mode is substantially the same as or smaller than the maximum value of the output current Iu in the first and second control modes. can do.

  Hereinafter, the present invention will be described using operations of the power conversion device in the boost mode (first control mode) and the backup mode (third control mode). The relationship between the operations of the power conversion device in the step-down mode (second control mode) and in the third control mode can be considered in the same way.

First, the operation of the inverter circuit 42 in the boost mode will be described with reference to FIGS.
FIG. 7 is a diagram for explaining control signals of switching elements Q1 and Q2 and switching elements S1 to S4 when inverter circuit 42 operates in the boost mode. The control circuit 101 generates a control signal for each element from the relationship between the AC voltage command Vu ^* and the voltage Vr of the AC power supply 1 in each control period belonging to the boost mode.
In the figure, the meanings of symbols described in each column are the same as those in FIG. 2 according to the first embodiment. However, the states of the control signals Gs3 and Gs4 of the switch elements S3 and S4 are added to the “control signal” column in this figure.

The power conversion device determines a region as follows and determines the states of the control signals G1, G2 and Gs1 to Gs4 of each element.
When the relationship between the AC voltage command Vu ^* and the voltage Vr is Vu ^* > Vr, the control period is set as the region 21. The region 21 is a region for the inverter circuit 42 to output the positive half wave of the voltage Vu.
Further, when the relationship between the AC voltage command Vu ^* and the voltage Vr is Vu ^* ≦ Vr, the control period is set as the region 22. The region 22 is a region for the inverter circuit 42 to output the negative half wave of the voltage Vu.
The pulse width command α in the region 21 and the region 22 is calculated using the following equations (7) and (8).

  Note that, in each of the regions 21 and 22, the element selected as the first element and the element selected as the second element are determined in advance. In addition, elements to be on-arm elements or off-arm elements are also determined in advance.

  In FIG. 7, “Hon” indicates a control signal of the element selected as the first element. “Lon” indicates a control signal of the element selected as the second element. The control signal “Lon” is a signal obtained by inverting the high level and the low level of the control signal “Hon”. “H” indicates a control signal of the element selected as the on-arm element. “L” indicates a control signal of the element selected as the off-arm element. When each signal is at a high level, the corresponding element is turned on. When each signal is at a low level, the corresponding element is turned off.

When the control period is the region 21, the inverter circuit 42 performs the same operation as the inverter circuit 41 in the region 11. When the control period is the region 22, the inverter circuit 42 operates in the same manner as the inverter circuit 41 in the region 12.
In other words, in the region 21, the switching element Q1 and the switching element S2 are alternately turned on / off. In the region 22, the switching element Q2 and the switching element S1 are alternately turned on / off. However, in the regions 21 and 22, the switch elements S3 and S4 are always in the off state.

Next, the operation when the inverter circuit 42 outputs the positive half wave of the voltage Vu in the region 21 will be described with reference to FIG. Note that the operation when the inverter circuit 42 outputs the negative half wave of the voltage Vu in the region 22 can be considered in the same manner as the operation in the region 21, and thus the description thereof is omitted.
In the region 21, a frequency at which the switching elements Q1, Q2 are turned on / off is a frequency f2A (first frequency). The period of the frequency f2A is T2A.

FIG. 8A shows the control signal “Hon” of the first element when the control period is the region 21. The control signal “Hon” is a signal that is turned on for a time T2AH and then turned off for a time T2AL in the control period T2A. Time T2AH is a time corresponding to the pulse width command α calculated by the above equation (7). For example, the time T2AH can be obtained by multiplying the cycle T2A of the control period by the pulse width command α.
8B to 8G show the on / off states of the switching elements Q1 and Q2 and the switching elements S1 to S4, respectively. In FIG. 8B and FIG. 8D, the hatched portion indicates a period during which the current Iu flows in the element. Also in this figure, the idle period in which the switching element Q1 and the switching element S2 are simultaneously turned off is omitted.

During the control period, the voltage Vu shown in FIG. 8H is output between the AC output terminals U-V. The voltage Vu becomes the positive voltage Vp for the time T2AH from the start point of the control period T2A, and then becomes the voltage Vr of the AC power supply 1 for the time T2AL. During the control period, the average value of the voltage Vu output between the AC output terminals U-V is equal to the AC voltage command Vu ^* .

  Further, the inverter circuit 42 outputs a current Iu shown in FIG. The current Iu flows through the path R2AH of the neutral point terminal O of the positive side terminal P of the DC power supply series circuit 30 → the switching element Q1 → the filter circuit 5 and the load 6 → DC power supply series circuit 30 for the time T2AH. At this time, the current Iu gradually increases. Current Iu flows through path R2AL of filter circuit 5 and load 6 → AC power supply 1 → switch element S1 → filter circuit 5 and load 6 for time T2AL. At this time, the current Iu gradually decreases.

By performing the above operation in each control period, the power converter can output the AC voltage Vu corresponding to the AC voltage command Vu ^* and supply power to the load.
Here, the current Iu flows through the reactor Lf1 as described above. The difference between the maximum value and the minimum value of the current Iu is the ripple current Ir2A. The maximum value of the ripple current Ir2A is determined such that the current Iu is smaller than the controllable current Im.
The ripple current Ir2A is determined by the inductance value of the reactor Lf1, the voltages Vp and Vr applied to the reactor Lf1, and the respective application times T2AH and T2AL. Moreover, the application time of the voltage applied to reactor Lf1 corresponds to frequency f2A at which switching element Q1 and switching element S2 are turned on / off.

Next, the operation of the inverter circuit 42 when the positive half wave of the voltage Vu is output in the backup mode will be described with reference to FIG. Note that the operation when the inverter circuit 42 outputs the negative half wave of the voltage Vu can be considered in the same way as the operation of outputting the positive half wave, and thus the description thereof is omitted.
In the backup mode, the switching elements Q1, Q2 are alternately turned on / off. The frequency at which the switching elements Q1, Q2 are turned on / off is defined as a frequency f2B (third frequency). The period of the frequency f2B is T2B.

  FIG. 9A shows the control signal “Hon” of the first element in the control period in which the positive half wave of the voltage Vu is output. The control signal “Hon” is a signal that is turned on for a time T2BH and then turned off for a time T2BL in the control period T2B. The time T2BH is a time corresponding to a pulse width command α calculated by equation (9) described later. For example, the time T2BH can be obtained by multiplying the period T2B of the control period by the pulse width command α.

FIGS. 9B to 9G show the on / off states of the switching elements Q1 and Q2 and the switching elements S1 to S4, respectively. The switching element Q1 performs an on / off operation in synchronization with the control signal Hon in the control period T2B. The switch element S4 performs an on / off operation in synchronization with a signal obtained by inverting the high level and the low level of the control signal Hon. In the control period T2B, the switch element S3 is turned on, and the switching element Q2 and the switch elements S1 and S2 remain off.
In FIG. 9B and FIG. 9F, the hatched portion indicates a period during which the current Iu flows in the element.

  In the backup mode, the pulse width command α when the positive half wave and the negative half wave of the voltage Vu are output is calculated using the following equations (9) and (10).

In the control signal, the voltage Vu shown in FIG. 9H is output between the AC output terminals U and V. The voltage Vu becomes a positive voltage Vp for a time T2BH from the start point of the control period, and then becomes a zero voltage Vz for a time T2BL. During the control period, the average value of the voltage Vu output between the AC output terminals U-V is equal to the AC voltage command Vu ^* .

  Further, the inverter circuit 42 outputs a current Iu shown in FIG. The current Iu flows through the path R2BH of the neutral point terminal O of the positive side terminal P of the DC power supply series circuit 30 → the switching element Q1 → the filter circuit 5 and the load 6 → DC power supply series circuit 30 for the time T2BH. At this time, the current Iu gradually increases. Current Iu flows through path R2BL of filter circuit 5 and load 6 → neutral point terminal O → switch element S3 → filter circuit 5 and load 6 during time T2BL. At this time, the current Iu gradually decreases. The difference between the maximum value and the minimum value of the current Iu is the ripple current Ir2B.

By performing the above operation in each control period, the power conversion device can output the AC voltage Vu corresponding to the AC voltage command Vu ^* even if the AC power supply 1 fails.

Here, an increase in the ripple current Ir2B generated in the vicinity of the phase where the fundamental wave of the current Iu is maximum is suppressed. The ripple current Ir2B is set to be substantially the same as the ripple current Ir2A generated in the vicinity of the same phase in the boost mode. Then, the maximum value of current Iu in the backup mode can be made substantially the same as the maximum value of current Iu in the boost mode.
Therefore, the frequency f2B is set to a frequency higher than the frequency f2A.

  For example, the frequency f2B is set according to the ratio of the voltage change width during the control period in the backup mode and the boost mode. In this case, the frequency f2B is calculated by the following equation (11).

The absolute value of the voltage Vp of the DC power supply Psp and the voltage Vn of the DC power supply Psn are the same. Therefore, the frequency f2B can also be calculated using the voltage Vn of the DC power supply Psn.
If the frequency f2B is set in this way, the time T2BH is shortened in inverse proportion to the frequency f2B, so that an increase in the ripple current Ir2B can be suppressed. Therefore, the frequency f2B may be set so that the ripple current Ir2B is substantially the same as the ripple current Ir2A.

  Further, in the vicinity of the phase where the fundamental wave of the current Iu is maximum, the difference between the voltage time product applied to the reactor Lf1 at the times T2BH and T2BL in the backup mode and the reactor at the times T2AH and T2AL in the boost mode The difference between the voltage time products applied to Lf1 may be substantially the same. For example, the frequency f2B is set so as to satisfy the following expression (12).

  If the frequency f2B is set so as to satisfy Expression (12), the difference between the voltage time products applied to the reactor Lf1 in the backup mode becomes substantially the same as the difference between the voltage time products applied in the boost mode. Therefore, an increase in the ripple current Ir2B is suppressed, and the ripple current Ir2B becomes substantially the same as the ripple current Ir2A.

  Moreover, if the temperature rise of switching element Q1, Q2, switching element S1-S4, and reactor Lf1 is accept | permitted, frequency f2B can also be made into a frequency higher than said frequency. In this case, the ripple current Ir2B can be made smaller than the ripple current Ir2A without increasing the inductance value of the reactor Lf1.

  Further, the frequency f2B may be set so that the total loss generated in the switching elements Q1 and Q2 and the switching elements S1 to S4 and the reactor Lf1 in the backup mode is minimized.

  In this way, the maximum value of the current Iu in the backup mode can be made substantially equal to or smaller than the maximum value of the current Iu in the boost mode without increasing the inductance value of the reactor Lf1. it can. Moreover, since it is not necessary to increase the number of turns of the coil of reactor Lf1, the enlargement of reactor Lf1 can be suppressed. Furthermore, since it is not necessary to increase the number of turns of the coil of the reactor Lf1, it is possible to suppress an increase in the copper loss of the reactor Lf1.

As in FIG. 5 shown in the first embodiment, the carrier signal Sc can be switched at a valley point. Thereby, the continuity and symmetry of the carrier signal Sc are maintained.
Further, since the power failure of the AC power supply 1 is normally restored in a short time, even if the inverter circuit 42 operates at the frequency f2B during this time, the temperature rise due to the increase in generated loss does not become a problem.

  When the power converter outputs the positive half wave of the voltage Vu in the second control mode, the switch element S1 is selected as the first element and the switch element S3 is selected as the second element. When the power conversion device outputs the negative half wave of the voltage Vu in the second control mode, the switch element S2 is selected as the first element, and the switch element S4 is selected as the second element. In either case, the other elements are off. However, this is only an example, and the first and second elements may be selected in other combinations as long as the voltage of the AC power supply 1 can be stepped down.

  The setting of the third frequency when the power conversion device operates in the second control mode and the third control mode is considered in the same manner as in the case of operating in the first control mode and the third control mode described above. be able to. By setting the third frequency, the maximum value of the current Iu in the third control mode is substantially the same as the maximum value of the current Iu in the second control mode without increasing the inductance value of the reactor Lf1, or A smaller current can be obtained.

  Further, when the power conversion device operates in the first, second, and third control modes, the third frequency is set in the same way as described above. By setting the third frequency, the maximum value of the current Iu in the third control mode is substantially equal to the maximum value of the current Iu in the first and second control modes without increasing the inductance value of the reactor Lf1. The current can be the same or less.

  Moreover, since it is not necessary to increase the number of turns of the coil of reactor Lf1, the enlargement of reactor Lf1 can be suppressed. Furthermore, since it is not necessary to increase the number of turns of the coil of the reactor Lf1, it is possible to suppress an increase in the copper loss of the reactor Lf1.

  The power conversion device to which the present invention is applied is an apparatus for supplying a stable voltage to a load even when a voltage fluctuation of the AC power supply and a power failure of the AC power supply occur, such as an instantaneous voltage drop compensation device or an uninterruptible power supply device. Can be applied.

1 AC power supply 2 Capacitor 3 Converter circuit 30 DC power supply series circuit 41, 42 Inverter circuit 5 Filter circuit 6 Load 100, 101 Control circuit

Claims (7)

Using a voltage of a DC power supply series circuit formed by connecting the first and second DC power supplies in series and a voltage of an AC power supply having one end connected to a connection point of the first and second DC power supplies It has an inverter that outputs AC voltage,
The inverter is
A switching element series circuit formed by connecting first and second switching elements in series, and connected to both ends of the DC power supply series circuit;
A first bidirectional switch having one end connected to a connection point of the first and second switching elements and the other end connected to the other end of the AC power supply;
A reactor connected between a connection point of the first and second switching elements and a load,
A first control mode for generating a predetermined AC voltage higher than the voltage of the AC power supply using the voltage of the AC power supply and the voltage of the DC power supply series circuit, the voltage of the AC power supply, and the DC power supply series circuit A second control mode for generating a predetermined AC voltage lower than the voltage of the AC power supply by using at least the voltage of the AC power supply, and a predetermined AC voltage using the voltage of the DC power supply series circuit. Operating in two or more control modes including at least one of the first control mode and the second control mode and the third control mode among the third control modes for generating
When the first and second switching elements are turned on and off in the first control mode, the frequency to turn on and off is the first frequency,
When the first and second switching elements are turned on / off in the second control mode, the frequency for the on / off operation is the second frequency,
When turning on and off the first and second switching elements in the third control mode, the frequency to turn on and off is a third frequency higher than the first and second frequencies,
When the inverter operates with a control mode of either the first or second control mode and the third control mode;
The third frequency is such that the ripple current included in the inverter output current in the third control mode near the phase where the fundamental wave of the inverter output current is maximum is the first or second near the phase. substantially the same so that the size or the ripple current to that power conversion apparatus characterized by being defined as from smaller the ripple current included in the inverter output current during the control mode. Using a voltage of a DC power supply series circuit formed by connecting the first and second DC power supplies in series and a voltage of an AC power supply having one end connected to a connection point of the first and second DC power supplies It has an inverter that outputs AC voltage,
The inverter is
A switching element series circuit formed by connecting first and second switching elements in series, and connected to both ends of the DC power supply series circuit;
A first bidirectional switch having one end connected to a connection point of the first and second switching elements and the other end connected to the other end of the AC power supply;
A reactor connected between a connection point of the first and second switching elements and a load,
A first control mode for generating a predetermined AC voltage higher than the voltage of the AC power supply using the voltage of the AC power supply and the voltage of the DC power supply series circuit, the voltage of the AC power supply, and the DC power supply series circuit A second control mode for generating a predetermined AC voltage lower than the voltage of the AC power supply by using at least the voltage of the AC power supply, and a predetermined AC voltage using the voltage of the DC power supply series circuit. Operating in two or more control modes including at least one of the first control mode and the second control mode and the third control mode among the third control modes for generating
When the first and second switching elements are turned on and off in the first control mode, the frequency to turn on and off is the first frequency,
When the first and second switching elements are turned on / off in the second control mode, the frequency for the on / off operation is the second frequency,
When turning on and off the first and second switching elements in the third control mode, the frequency to turn on and off is a third frequency higher than the first and second frequencies,
When the inverter operates with a control mode of either the first or second control mode and the third control mode;
The third frequency is a voltage change width applied to the reactor in the third control mode in the vicinity of the phase where the fundamental wave of the inverter output current is maximum, and the first or second frequency in the vicinity of the phase. The coefficient obtained by dividing by the voltage change width applied to the reactor in the control mode is set to be substantially the same as or higher than the frequency obtained by multiplying the first frequency. it characterized by that power converter. Using a voltage of a DC power supply series circuit formed by connecting the first and second DC power supplies in series and a voltage of an AC power supply having one end connected to a connection point of the first and second DC power supplies It has an inverter that outputs AC voltage,
The inverter is
A switching element series circuit formed by connecting first and second switching elements in series, and connected to both ends of the DC power supply series circuit;
A first bidirectional switch having one end connected to a connection point of the first and second switching elements and the other end connected to the other end of the AC power supply;
A reactor connected between a connection point of the first and second switching elements and a load,
A first control mode for generating a predetermined AC voltage higher than the voltage of the AC power supply using the voltage of the AC power supply and the voltage of the DC power supply series circuit, the voltage of the AC power supply, and the DC power supply series circuit A second control mode for generating a predetermined AC voltage lower than the voltage of the AC power supply by using at least the voltage of the AC power supply, and a predetermined AC voltage using the voltage of the DC power supply series circuit. Operating in two or more control modes including at least one of the first control mode and the second control mode and the third control mode among the third control modes for generating
When the first and second switching elements are turned on and off in the first control mode, the frequency to turn on and off is the first frequency,
When the first and second switching elements are turned on / off in the second control mode, the frequency for the on / off operation is the second frequency,
When turning on and off the first and second switching elements in the third control mode, the frequency to turn on and off is a third frequency higher than the first and second frequencies,
When the inverter operates with a control mode of either the first or second control mode and the third control mode;
The difference between the voltage time products of the two levels of voltages applied to the reactor in the third control mode in the vicinity of the phase where the fundamental wave of the inverter output current is maximum is the third frequency. So that the difference between the voltage time products of the two levels of voltages applied to the reactor in the first or second control mode is substantially the same as or smaller than the difference between the voltage time products. it characterized in that stipulated power converter. Using a voltage of a DC power supply series circuit formed by connecting the first and second DC power supplies in series and a voltage of an AC power supply having one end connected to a connection point of the first and second DC power supplies It has an inverter that outputs AC voltage,
The inverter is
A switching element series circuit formed by connecting first and second switching elements in series, and connected to both ends of the DC power supply series circuit;
A first bidirectional switch having one end connected to a connection point of the first and second switching elements and the other end connected to the other end of the AC power supply;
A reactor connected between a connection point of the first and second switching elements and a load,
A first control mode for generating a predetermined AC voltage higher than the voltage of the AC power supply using the voltage of the AC power supply and the voltage of the DC power supply series circuit, the voltage of the AC power supply, and the DC power supply series circuit A second control mode for generating a predetermined AC voltage lower than the voltage of the AC power supply by using at least the voltage of the AC power supply, and a predetermined AC voltage using the voltage of the DC power supply series circuit. Operating in two or more control modes including at least one of the first control mode and the second control mode and the third control mode among the third control modes for generating
When the first and second switching elements are turned on and off in the first control mode, the frequency to turn on and off is the first frequency,
When the first and second switching elements are turned on / off in the second control mode, the frequency for the on / off operation is the second frequency,
When turning on and off the first and second switching elements in the third control mode, the frequency to turn on and off is a third frequency higher than the first and second frequencies,
When the inverter operates with the first, second and third control modes;
The third frequency is such that the ripple current included in the inverter output current in the third control mode near the phase where the fundamental wave of the inverter output current is maximum is the first and second frequencies near the phase. substantially the same size as the composed manner or to that power converter characterized in that it is determined to be smaller than the ripple current and the ripple current included in any of the control mode of the inverter output current. Using a voltage of a DC power supply series circuit formed by connecting the first and second DC power supplies in series and a voltage of an AC power supply having one end connected to a connection point of the first and second DC power supplies It has an inverter that outputs AC voltage,
The inverter is
A switching element series circuit formed by connecting first and second switching elements in series, and connected to both ends of the DC power supply series circuit;
A first bidirectional switch having one end connected to a connection point of the first and second switching elements and the other end connected to the other end of the AC power supply;
A reactor connected between a connection point of the first and second switching elements and a load,
A first control mode for generating a predetermined AC voltage higher than the voltage of the AC power supply using the voltage of the AC power supply and the voltage of the DC power supply series circuit, the voltage of the AC power supply, and the DC power supply series circuit A second control mode for generating a predetermined AC voltage lower than the voltage of the AC power supply by using at least the voltage of the AC power supply, and a predetermined AC voltage using the voltage of the DC power supply series circuit. Operating in two or more control modes including at least one of the first control mode and the second control mode and the third control mode among the third control modes for generating
When the first and second switching elements are turned on and off in the first control mode, the frequency to turn on and off is the first frequency,
When the first and second switching elements are turned on / off in the second control mode, the frequency for the on / off operation is the second frequency,
When turning on and off the first and second switching elements in the third control mode, the frequency to turn on and off is a third frequency higher than the first and second frequencies,
When the inverter operates with the first, second and third control modes;
The third frequency is a voltage change width applied to the reactor in the third control mode in the vicinity of the phase where the fundamental wave of the inverter output current is maximum, and the first and second frequencies in the vicinity of the phase. The coefficient obtained by dividing by one of the voltage change widths applied to the reactor in the control mode is substantially the same as or higher than the frequency obtained by multiplying the first frequency. be that power converter characterized in that it is specified in. Using a voltage of a DC power supply series circuit formed by connecting the first and second DC power supplies in series and a voltage of an AC power supply having one end connected to a connection point of the first and second DC power supplies It has an inverter that outputs AC voltage,
The inverter is
A switching element series circuit formed by connecting first and second switching elements in series, and connected to both ends of the DC power supply series circuit;
A first bidirectional switch having one end connected to a connection point of the first and second switching elements and the other end connected to the other end of the AC power supply;
A reactor connected between a connection point of the first and second switching elements and a load,
A first control mode for generating a predetermined AC voltage higher than the voltage of the AC power supply using the voltage of the AC power supply and the voltage of the DC power supply series circuit, the voltage of the AC power supply, and the DC power supply series circuit A second control mode for generating a predetermined AC voltage lower than the voltage of the AC power supply by using at least the voltage of the AC power supply, and a predetermined AC voltage using the voltage of the DC power supply series circuit. Operating in two or more control modes including at least one of the first control mode and the second control mode and the third control mode among the third control modes for generating
When the first and second switching elements are turned on and off in the first control mode, the frequency to turn on and off is the first frequency,
When the first and second switching elements are turned on / off in the second control mode, the frequency for the on / off operation is the second frequency,
When turning on and off the first and second switching elements in the third control mode, the frequency to turn on and off is a third frequency higher than the first and second frequencies,
When the inverter operates with the first, second and third control modes;
The difference between the voltage time products of the two levels of voltages applied to the reactor in the third control mode in the vicinity of the phase where the fundamental wave of the inverter output current is maximum is the third frequency. Near the difference between the voltage-time products of the two levels of voltages applied to the reactor in the first and second control modes, or smaller than the difference between the voltage-time products. power converter characterized by being defined as. The inverter further includes a second bidirectional switch connected between a connection point of the first and second switching elements and a connection point of the first and second DC power supplies. The power conversion device according to any one of claims 1 to 6, wherein: