JP6562301B2 - Bidirectional switch circuit, power converter using the same, and control method thereof - Google Patents

Description

  The present invention relates to a bidirectional switch circuit capable of conducting and interrupting current in both directions, and further relates to a power converter using the circuit and a control method thereof.

  In order to connect a three-phase AC power source and a DC load such as a storage battery, an insulating bidirectional AC / DC converter is used. As the insulation type bidirectional AC / DC converter of FIG. 26 (a), a three-phase AC voltage is converted to a constant value DC by a step-up AC / DC converter after insulation using a transformer having a commercial frequency of 50 Hz or 60 Hz. There are two power conversion systems that convert the voltage into a voltage and then adjust the DC voltage with a DC / DC converter. In this system, a commercial frequency transformer makes the system large and heavy.

  In order to reduce the size of the system, a bidirectional AC / DC converter using a high-frequency transformer shown in FIG. 26B instead of a commercial transformer has been proposed. A bidirectional AC / DC converter circuit using a high-frequency transformer first converts a three-phase AC voltage into a constant DC voltage using an AC / DC converter, and then converts the DC voltage into a high-frequency AC voltage using an inverter. This is a three-time power conversion method in which insulation is performed by the high-frequency transformer of FIG. 26 (b) and then re-conversion to a DC voltage by an AC / DC converter. By using a high-frequency transformer, the volume of the transformer can be greatly reduced, and in addition, soft switching can be applied in DC / AC / DC power conversion via the high-frequency transformer, realizing low loss (non-patent literature). 1). However, since the number of power conversions is as many as three, the volume of the power conversion unit increases, and the first stage AC / DC converter has no limit in reducing switching loss because soft switching cannot be applied. In addition, since a smooth electrolytic capacitor having a short life is generally used for the direct current portion, there is also a problem of maintenance.

  In a system using a high-frequency transformer, a system using a matrix converter that directly converts a three-phase AC voltage to a high-frequency AC voltage has been proposed in order to reduce the size and loss of the power converter on the primary side of the transformer. Power conversion on the primary side of the transformer can be performed once, and a smoothing electrolytic capacitor on the primary side of the transformer is not necessary. However, when switching the switching element on / off, a switching loss is generated due to the product of the current flowing through the switching element and the voltage applied to the switching element, so there is a limit to miniaturization and high frequency. In Patent Document 1, a proposal has been made in which soft switching for turning on / off a switching element is attempted for all switching elements by setting either a current flowing through the switching element or a voltage applied to the switching element to zero.

Inoue Shigenori, Akagi Yasufumi, “Operating Voltage and Loss Analysis of Bidirectional Insulated DC / DC Converter”, IEEJ Transactions D (Industrial Application Division), 2007, Vol. 127, no. 2, p. 189-197

International Publication No. 2014/0208898

  However, in the above-mentioned Patent Document 1, as a bidirectional switch configuration of the transformer primary power converter, two switches in which an antiparallel diode and a parallel capacitor are connected to a switching element are configured in reverse series. Yes. The bidirectional switch requires two switching elements, two diodes, and two capacitors, and many components are required.

  Further, in Patent Document 1 described above, the power source current is not described as a sine wave current, but only two-phase switching is performed in one cycle of the high-frequency transformer voltage, and the power source current is converted into a sine wave. Cannot be realized. Therefore, such a power converter cannot be directly connected to the power supply system due to high-frequency current regulation, and when connected, a large filter circuit for removing high-frequency noise is required. There was a problem that the physique was large and cost was required.

  The present invention has been made in view of the above, and an object thereof is to propose a bidirectional switch circuit capable of realizing soft switching with a simple circuit configuration, a power converter using the same, and a control method thereof. .

A first bidirectional switch circuit according to the present invention includes:
Two reverse blocking switching elements connected in reverse parallel;
And a single soft switching capacitor connected in parallel with the switching element connected in reverse parallel.

  According to such a configuration, a bidirectional switch capable of soft switching can be realized with a simple circuit configuration.

  Note that the “bidirectional switch” in this specification refers to a switching circuit that allows current to flow in both directions and can be cut off. In addition, the “reverse blocking type switching element” in the present specification refers to a switching element having an ability to withstand a voltage from a direction opposite to a current conduction direction (reverse blocking ability).

Further, the second bidirectional switch circuit according to the present invention includes:
Two switching elements with freewheeling diodes connected in reverse series;
One soft switching capacitor connected in parallel to both ends of the switching element connected in reverse series.

  According to such a configuration, a bidirectional switch having the same function as that of the first bidirectional switch circuit can be realized by a switching element having no reverse blocking capability.

  The first bidirectional switch circuit and the second bidirectional switch circuit described above are more efficient than the bidirectional switch circuit proposed in Patent Document 1, but eliminate the risk of a short circuit. Although there is an effect that it is safe, it will be described later.

Moreover, according to the soft switching leg circuit according to the present invention,
With multiple input terminals and one output terminal,
Each of the input terminals and the output terminal are connected by the first bidirectional switch circuit or the second bidirectional switch circuit described above,
Two terminals of the plurality of input terminals are both connected by a filter capacitor.

  According to such a configuration, a leg circuit capable of soft switching can be configured with a simple circuit configuration.

The first power converter according to the present invention is:
A U1-phase terminal, a V1-phase terminal, and a W1-phase terminal, which are insulated from the primary side and the secondary side by a high-frequency transformer and connected to a three-phase AC power source on the primary side,
The high-frequency transformer has a first connection terminal and a second connection terminal on the primary side,
The U1 phase terminal, the V1 phase terminal, and the W1 phase terminal and the first connection terminal;
And the U1 phase terminal, the V1 phase terminal, the W1 phase terminal and the second connection terminal,
Are respectively connected by the above-mentioned soft switching leg circuit.

  According to such a configuration, an insulated power converter capable of soft switching can be configured with a simple circuit configuration.

In the above first power converter,
The power converter further includes a positive terminal and a negative terminal connected to a DC power source on the secondary side,
The high-frequency transformer further includes a third connection terminal and a fourth connection terminal on the secondary side,
The third connection terminal and the positive terminal, the third connection terminal and the negative terminal, the fourth connection terminal and the positive terminal, the fourth connection terminal and the negative terminal, and a switching element with a freewheeling diode The soft switching capacitors may be connected by a soft switching arm circuit connected in parallel.

  According to such a configuration, an isolated AC / DC converter capable of soft switching in all switching elements can be configured with a simple circuit configuration.

The second power converter according to the present invention is
The secondary side is provided with a U1-phase terminal, a V1-phase terminal, and a W1-phase terminal that are insulated from a primary side and a secondary side by a high-frequency transformer, and to which the first three-phase AC power supply is connected. A power converter comprising a U2-phase terminal, a V2-phase terminal, and a W2-phase terminal to which a second three-phase AC power supply is connected,
The high-frequency transformer has a first connection terminal and a second connection terminal on the primary side, and has a third connection terminal and a fourth connection terminal on the secondary side,
The U1 phase terminal, the V1 phase terminal, and the W1 phase terminal and the first connection terminal;
The U1 phase terminal, the V1 phase terminal, the W1 phase terminal and the second connection terminal,
The U2-phase terminal, the V2-phase terminal, and the W2-phase terminal and the third connection terminal,
And the U2-phase terminal, the V2-phase terminal, and the W2-phase terminal and the fourth connection terminal,
Are connected by the above-described soft switching leg circuit.

  According to such a configuration, it is possible to configure an insulated AC / AC inverter capable of soft switching in all switching elements with a simple circuit configuration.

The third power converter according to the present invention is
A U1-phase terminal, a V1-phase terminal, and a W1-phase terminal to which a three-phase AC power supply is connected;
A positive terminal and a negative terminal to which a DC power supply is connected;
An inductor;
A first connection point, a second connection point, and a third connection point,
The U1 phase terminal, the V1 phase terminal, and the W1 phase terminal and the first connection point, and the U1 phase terminal, the V1 phase terminal, and the W1 phase terminal and the third connection point,
Are connected by the above-mentioned soft switching leg circuit,
The second connection point and the positive terminal, the second connection point and the negative terminal, the third connection point and the positive terminal, and the third connection point and the negative terminal are free-wheeling diodes, respectively. Is connected by a soft switching arm circuit in which a soft switching capacitor is connected in parallel to the attached switching element,
The first connection point and the second connection point are connected by an inductor.

  According to such a configuration, it is possible to configure an AC / DC converter capable of soft switching in all switching elements with a simple circuit configuration without using a high-frequency transformer.

Moreover, the method for controlling the power converter according to the present invention includes:
In the first power converter or the second power converter,
Among the U1 phase terminal, the V1 phase terminal, and the W1 phase terminal, in descending order of the absolute value of the potential, the x phase, the y phase, and the z phase,
Further, if the first half of the control cycle of the control method is a first half cycle and the second half is a second half cycle,
When the x-phase potential is positive,
In the first half cycle, the bidirectional switch between the first connection terminal and the x-phase is fixed in an ON state;
In the second half cycle, the bidirectional switch between the second connection terminal and the x phase is fixed in an ON state,
When the x-phase potential is negative,
In the first half cycle, the bidirectional switch between the second connection terminal and the x-phase is fixed in an ON state;
In the second half cycle, the bidirectional switch between the first connection terminal and the x-phase is fixed to an ON state,
The other connection terminals of the first connection terminal and the second connection terminal are:
During power transmission from the primary side to the secondary side,
From the bidirectional switch between the other connection terminal and the x phase, commutation is performed in all three phases in the order of the bidirectional switch between the y phase, the z phase, and the x phase,
During power transmission from the secondary side to the primary side,
From the bidirectional switch between the other connection terminal and the x phase, commutation is performed in all three phases in the order of the z phase, the y phase, and the bidirectional switch between the x phases.

  In this specification, “turning on the bidirectional switch” means that a switching signal is given to one or both of the two switching elements of the bidirectional switch to make the element conductive. For example, when the switching element is an IGBT, a driving voltage is applied to the gate to make the collector-emitter conductive. Here, when a capacitor is connected in parallel to the switching element for soft switching, it may take time until the element actually becomes conductive after a switching signal is given to the element. In this case, “turning on the bidirectional switch” refers to giving a switching signal for conduction to one or both of the two switching elements.

  Further, in this specification, “commutation” means that when a bidirectional switch in a leg circuit is on, the bidirectional switch is turned off and another bidirectional switch in the leg circuit is turned on. The bidirectional switch through which current passes is switched by changing the ON state of the bidirectional switch in the leg circuit.

  According to such a configuration, the transformer primary high-frequency voltage can be generated using not only the two-phase voltage of the three-phase AC power source on the primary side but also the voltage of all three phases, and the three-phase is reduced while reducing the switching loss. The current of the AC power supply can be approximated to a sine wave.

In the above power converter control method,
Two three-input one-output leg circuits in which the U1-phase terminal, the V1-phase terminal, and the W1-phase terminal are input terminals, and either the first connection terminal or the second connection terminal is an output terminal. Each one
When the output current of the leg circuit is positive, the leg circuit is switched to a bidirectional switch connected to an input terminal having a lower potential than the input terminal to which the bidirectional switch that is turned on is connected. Do the flow
When the output current of the leg circuit is negative, the output is transferred to the bidirectional switch connected to the input terminal having a higher potential than the input terminal connected to the bidirectional switch that is turned on in the leg circuit. A flow may be performed.

  According to such a configuration, soft switching can be realized in all the switching elements on the primary side, and the current of the three-phase AC power supply can be brought close to a sine wave while reducing the switching loss.

  As described above, according to the bidirectional switch circuit of the present invention, it is possible to realize a bidirectional switch that can be soft-switched with a simple circuit configuration and is excellent in safety.

The figure which shows the structure of the leg circuit using the bidirectional | two-way switch comprised by the reverse blocking type switching element Diagram showing soft switching commutation operation at positive output current Diagram showing soft switching commutation mode at positive output current Diagram showing soft switching commutation operation at negative output current Diagram showing soft switching commutation mode at negative output current The figure which shows the structure of the leg circuit using the bidirectional | two-way switch comprised by the switching element with a free-wheeling diode. (A) 1st circuit structure (b) 2nd circuit structure The figure which shows the structure of the leg circuit of 3 inputs 1 output The figure which shows the insulation type AC / DC power converter circuit which used the high frequency transformer Diagram showing three-phase power supply voltage waveform The figure which shows the voltage current waveform of the high frequency transformer at the time of the electric power transmission from the primary side to the secondary side at the time of Fig.9 (a) Diagram showing soft switching commutation of secondary converter The figure which shows the voltage current waveform of the high frequency transformer at the time of the electric power transmission from the primary side to the secondary side at the time of FIG.9 (b) The figure which shows the voltage current waveform of the high frequency transformer at the time of electric power transmission from the secondary side to the primary side Diagram showing how to generate a gate signal Diagram showing PWM control method The figure which shows the experimental system structure in Experimental example 1 Diagram showing experimental waveforms Enlarged view of experimental waveform The figure which shows the waveform at the time of switching from _Swg- > _Sug (a) At the time of soft switching (b) At the time of hard switching The figure which shows the waveform at the time of switching from S _jn → S _jp (a) At the time of soft switching (b) At the time of hard switching The figure which shows the non-insulation type AC / DC power converter circuit which used the inductor The figure which shows the insulation type AC / DC power converter circuit using a coupling-type wireless electric power feeding system The figure which shows the insulation type AC / AC power converter circuit using a high frequency transformer The figure which shows the voltage current waveform of the high frequency transformer at the time of the electric power transmission from the primary side to the secondary side of the insulation type AC / AC power converter circuit using a high frequency transformer The figure which shows the insulation type AC / AC power converter circuit using a coupling-type wireless electric power feeding system The figure which shows the circuit structure of the conventional power converter The figure which shows the structure of the conventional leg circuit The figure which shows the operation at the time of power supply voltage change in the conventional leg circuit The figure which shows the soft switching commutation operation at the time of the positive output current in the conventional leg circuit The figure which shows the soft switching commutation mode at the time of positive output current in the conventional leg circuit

(First embodiment)
FIG. 1 is a diagram illustrating a configuration of a soft switching circuit (leg circuit) using a first bidirectional switch. There are two input terminals u and v and an output terminal g, and a filter capacitor _Cf is connected between the input terminals. A bidirectional switch S _ug is connected between the input terminal u and the output terminal g, and a bidirectional switch S _vg is connected between the input terminal v and the output terminal g. The bidirectional switch S _ug is configured by connecting in parallel a switching element S _ugR that _passes a positive output current i, a switching element S _ugL that _passes a negative output current i, and a soft switching capacitor C _soft1 . The bidirectional switch S _vg has the same configuration as the bidirectional switch S _ug, and is configured by connecting switching elements S _vgR and S _vgL and a soft switching capacitor C _soft1 in parallel. The switching elements S _ugL , S _ugR , S _vgL , S _vgR constituting the bidirectional switches S _ug , S _vg respectively have a reverse blocking capability to withstand a voltage from the reverse direction. In this circuit, commutation between bidirectional switches can be soft switched (zero voltage switching). Further, the voltage e _uv between the input terminals u and v can give positive and negative DC voltage or AC voltage.

  As the switching element, a power transistor made of a semiconductor such as GaN can be used in addition to an IGBT or MOS-FET made of a semiconductor such as Si or SiC. Thereby, a bidirectional switch having a low on-resistance, a high breakdown voltage, and capable of high-speed switching can be realized.

  Hereinafter, the principle of realizing soft switching by the leg circuit according to the present embodiment will be described.

FIG. 2 illustrates the soft switching commutation operation from the high input potential bidirectional switch S _ug to the low input potential bidirectional switch S _vg when the input voltage e _uv is positive and the output current i is positive. Show.

FIG. 3 shows a circuit connection state in the commutation operation mode of FIG. In mode ₁ until time t <t _{1 in} FIG. 2, the connection state of mode 1 shown in FIG. 3A is obtained, a gate signal is given to switching elements S _ugR and S _ugL , and output current i is switched It flows as a current _{i sug} element, the capacitor voltage _{v ug} of the bidirectional switch _{S ug} has become zero. Further, the capacitor voltage v _vg = −e _uv of the bidirectional switch S _vg is charged to a negative input voltage.

At time t = _{t 1,} when the gate signal of the switching element _{S UGR} and _{S UGL} is turned off, since the parallel capacitor voltage _{v ug} is zero, the switching element _{S UGR} is turned off at the zero voltage switching. Transition is made to mode 2 in FIG. 2, and a connection state in mode 2 shown in FIG. 3B is obtained. In mode 2, the output current i is shunted to the capacitors of the two bidirectional switches, and flows as the capacitor current i _cug = i _cvg = i / 2. Capacitor voltage _{v ug} of the bidirectional switch _{S ug} is charged to the input voltage _{e uv,} capacitor voltage _{v CVG} bidirectional switch _{S vg} is discharged to zero voltage, mode 2 is terminated. The gate signals of the switching elements S _ugR and S _ugL are turned off, and after the turn-off time T _{off has} elapsed, a gate signal is given to the switching element S _vgR at the commutation destination, but is reverse-biased by the parallel capacitor voltage v _vg The switching element S _vgR is never turned on.

When the capacitor voltage v _vg of the bidirectional switch S _vg becomes zero at time t = t ₂ , the switching element S _vgR is turned on by zero voltage switching. A transition is made to mode 3 in FIG. 2, and a connection state in mode 3 shown in FIG. 3C is obtained. The output current i flows as a current isvg switching element, the capacitor voltage _{v vg} is zero bidirectional switch _{S vg,} capacitor voltage _v ug _{= e uv} bidirectional switch _{S ug} is charged to the input voltage.

After the maximum permissible time T _2max for _commutation has elapsed, the mode transitions to mode 4 in FIG. 2 to establish the connection state in mode 4 in FIG. That is, a gate signal is given to the switching element S _vgL so that the switching element S _vgL is turned on by zero current switching when the output current i becomes negative.

Here, the _relationship between the maximum allowable time T _2max required for commutation and the minimum current value I _1min of the absolute value | i | of the output current is derived. In this commutation, when the output current i is zero, the voltage of the capacitor does not change in the mode 2 of FIG. 2, so that soft switching cannot be performed. Therefore, there is a minimum current value I _1min of the absolute value | i | of the output current for soft switching. _Assuming that the maximum allowable time of the time T _{2 in} mode 2 in FIG. 2 is T _2max , the minimum current value I _1min is obtained by the following equation.

[Formula 1]

When the input voltage e _uv is a negative voltage and the output current i is a positive current, the operation of the bidirectional switches S _ug and S _vg is switched to change the low input potential from the bidirectional switch S _{vg having a} high input potential. Soft switching can be performed in the commutation to the bidirectional switch S _ug . That is, when the output current i is a positive current, soft switching can be performed in commutation from a high input potential bidirectional switch to a low input potential bidirectional switch.

FIG. 4 shows the soft switching commutation operation from the low input potential bidirectional switch S _vg to the high input potential bidirectional switch S _ug when the input voltage e _uv is positive and the output current i is negative. Show.

FIG. 5 shows a circuit connection state in the commutation operation mode of FIG. In mode ₁ until time t <t _{1 in} FIG. 4, the connection state of mode 1 shown in FIG. 5A is obtained, a gate signal is given to switching elements S _vgL and S _vgR , and output current i is switched flows as a current _{i svg} element, the capacitor voltage _{v vg} of the bidirectional switch _{S vg} has become zero. The capacitor voltage v _ug = e _uv of the bidirectional switch S _ug is charged to the input voltage.

When the gate signals of the switching elements S _vgL and S _vgR are turned off at time t = t ₁ , since the parallel capacitor voltage v _vg is zero, the switching element S _vgL is turned off by zero voltage switching. Transition is made to mode 2 in FIG. 4, and the connection state in mode 2 shown in FIG. 5B is obtained. In mode 2, the output current i is shunted to the capacitors of the two bidirectional switches, and flows as the capacitor current i _cug = i _cvg = i / 2. Capacitor voltage _{v vg} of the bidirectional switch _{S vg} is charged to a negative input voltage _{-e uv,} capacitor voltage _{v ug} of the bidirectional switch _{S ug} is discharged to zero voltage, mode 2 is terminated. _After the gate signals of the switching elements S _vgL and S _vgR are turned off and the turn-off time T _{off has} elapsed, the gate signal is given to the switching element S _ugL at the commutation destination, but is reverse-biased by the parallel capacitor voltage v _ug . The switching element S _ugL is not turned on.

When the capacitor voltage v _ug of the bidirectional switch S _ug becomes zero at time t = t ₂ , the switching element S _ugL is turned on by zero voltage switching. A transition is made to mode 3 in FIG. 4, and a connection state in mode 3 shown in FIG. 5C is obtained. The output current i flows as a current _{i sug} switching element, the capacitor voltage _{v ug} of the bidirectional switch _{S ug} to zero, the capacitor voltage _v vg = _{-e uv} bidirectional switch _{S vg} is charged to the negative input voltage ing.

After the maximum permissible time _T2max for _commutation has elapsed, the mode transitions to mode 4 in FIG. That is, a gate signal is given to the switching element _SvgR so that the switching element _SvgR is turned on by zero current switching when the output current i becomes positive.

In this commutation, the minimum value of the absolute value | i | of the output current for soft switching is the output current i of Equation 1 _assuming that the maximum allowable time of the time T ₂ of mode 2 in FIG. 4 is T _2max. Is equal to the positive minimum current value I _{1 min} .

When the input voltage e _uv is a negative voltage and the output current i is a negative current, the operation of the bidirectional switches S _ug and S _vg is switched to change the low input potential bidirectional switch S _ug to a higher input potential. Soft switching can be performed in commutation to the bidirectional switch _Svg . That is, when the output current i is a negative current, soft switching is realized in commutation from the low input potential bidirectional switch to the high input potential bidirectional switch.

(Second Embodiment)
FIG. 6 is a diagram illustrating a configuration of a leg circuit using the second bidirectional switch. In the leg circuit according to the second embodiment shown in FIG. 6, the leg circuit according to the first embodiment shown in FIG. 1 is configured by a bidirectional switch having a diode in antiparallel with the switching element. FIG. 6A shows a first circuit configuration according to this embodiment, and FIG. 6B shows a second circuit configuration. In the first circuit configuration, the two switching elements of the bidirectional switch are connected in reverse series in such a direction as to conduct current from the input / output terminals toward the connection point between the switching elements. On the other hand, in the second circuit configuration, they are connected in reverse series in such a direction that current is conducted from the connection point of the switching elements to the input / output terminal.

Bidirectional switch S _ug between the input terminals u output terminal g is connected in series with element connected anti-parallel diode to the switching element S _UGR, the elements connected to inverse parallel diode to the switching element S _UGL reversed, Further, a soft switching capacitor C _soft1 is connected in parallel with the series element. Bidirectional switch S _vg is the same configuration as the bidirectional switch S _ug, connected in series with element connected anti-parallel diode to the switching element S _Vgr, the elements connected to inverse parallel diode to the switching element S _VGL reversed In addition, a soft switching capacitor C _soft1 is connected in parallel with the series element. This circuit performs the same operation as the leg circuit of FIG. 1, and the operation waveforms of FIGS. 2 and 4 are established. That is, when the output current i is a positive current, in the commutation from the high input potential bidirectional switch to the low input potential bidirectional switch, when the output current i is a negative current, the low input potential In the commutation from the bidirectional switch to the bidirectional switch having a high input potential, soft switching is realized.

  Note that, unlike the first embodiment, the switching element in the present embodiment does not need to have reverse blocking capability.

  Here, a comparison between the bidirectional switch according to the second embodiment and the bidirectional switch proposed in Patent Document 1 will be described in detail.

  As already described, Patent Document 1 proposes a soft switching of all switching elements. However, as a bidirectional switch configuration of the power converter on the transformer primary side, two switches in which an antiparallel diode and a parallel capacitor are connected to the switching element are configured in reverse series. The bidirectional switch requires two switching elements, two diodes, and two capacitors, and many parts are required. An application method in the case where a reverse blocking type switching element having no antiparallel diode is configured as a bidirectional switch is not described.

  Further, in the conventional circuit configuration, the charge of the parallel capacitor of the switching element that is turned off cannot be discharged, and the degree of freedom during switch operation is limited. In addition, due to changes in the power supply voltage, the capacitor that wants to keep the voltage at zero accumulates electric charge, generates voltage, and the charge is released by turning on the switching element. Had the problem of. Further, in the commutation, when the signs of the power supplies are different, a power supply short circuit occurs, which not only increases the loss but also has a safety problem.

The problem of loss generation is specifically described below. FIG. 27 shows a configuration of a leg circuit that performs a soft switching operation in the power converter of Patent Document 1. There are input terminals u and v and an output terminal g, and a voltage source e _uv is connected between the input terminals. Bidirectional switch between the input terminal u output terminal g is an element connected anti-parallel diode and a parallel capacitor to the switching element S _UGR, the element connected to the anti-parallel diode parallel capacitor to the switching element S _UGL reversed It is configured in series connection. The bidirectional switch between v and g has the same configuration as the bidirectional switch between u and g.

FIG. 28 shows a connection state when the input voltage e _uv is a positive voltage and the switching elements S _vgR and S _vgL are on in Patent Document 1. In FIG. (A), the switching element _{S UGR,} the voltage of the parallel capacitor of the _{S UGL} is adapted to _{v ugR = e uv, v ugL} = 0 respectively. The capacitor voltage v _ugL wants to remain zero, but the power supply voltage e _uv is an AC voltage. When the power supply voltage changes to e _uv −2ΔV _o , the parallel capacitors of the switching elements S _ugR and S _ugL are charged. (B), current flows as shown in FIG. _7B , and the parallel capacitor voltage of the switching element _SugR is v _ugR = e _uv −ΔV _o , and the switching element S _ugL The parallel capacitor voltage is v _ugL = −ΔV _o . In the commutation operation from the v phase to u, when the switching element S _ugL is turned on, the parallel capacitor voltage v _ugL = −ΔV _o is short-circuited, and a loss is generated. Since the power supply voltage is constantly changing, such a loss always occurs.

FIG. 29 shows a case where the input voltage e _uv is a positive voltage and the output current i is a positive current from the u phase having a high input potential to the v phase having a low input potential in the conventional leg circuit shown in FIG. The soft switching commutation operation is shown. FIG. 30 shows a circuit connection state in the commutation operation mode of FIG. In mode ₁ up to time t <t _{1 in} FIG. 29, the connection state of FIG. _30A is obtained, a gate signal is given to switching element S _ugR , and output current i flows through switching element S _ugR . The u-phase capacitor voltages v _ugR and v _ugL are both zero. Further, the v-phase capacitor voltage v _vgR = 0, and v _vgL = −e _uv is charged to a negative input voltage. In preparation for commutation, a gate signal is _applied to the switching element S _vgR to ensure a discharge path with a capacitor voltage v _vgL = 0.

When the gate signal of the switching element S _ugR is turned off at time t = t ₁ , since the parallel capacitor voltage v _ugR is zero, the switching element S _ugR is turned off by zero voltage switching. Transition is made to mode 2 in FIG. 29, and the connection state of mode 2 in FIG. 30 (b) is obtained. In mode 2, the output current i is equally divided into the u-phase and the v-phase, and i _ug = i _vg = i / 2 flows. Due to the u-phase current i _ug = i / 2, the voltage of the parallel capacitor of the switching element S _ugR is charged to the input voltage e _uv . v-phase current _i vg = i / 2 passes through the switching element _{S UGR,} to discharge the parallel capacitor of the switching element _{S UGL} to zero voltage, to end the mode 2.

When the v-phase capacitor voltage v _vgL becomes zero at time t = t ₂ , a diode parallel to the switching element S _vgL is turned on by zero voltage switching. Transition is made to mode 3 in FIG. 29, and the connection state of mode 3 in FIG. 30 (c) is obtained. The output current i flows through a diode parallel to the switching element S _vgR and the switching element S _vgL . The v-phase capacitor voltages v _vgR and v _vgL are both zero, the u-phase capacitor voltage v _ugR is charged to the input voltage e _uv , and v _ugL is zero.

In mode 1 of this commutation operation, a gate signal must be given to the switching element S _vgR in order to ensure a discharge path of the capacitor voltage v _vgL = −e _uv . The power supply voltage e _uv is an alternating current, and an accurate voltage code may not be detected near the voltage zero due to the accuracy of the detector or detection delay. If the actual voltage is negative, as is apparent from FIG. _30A , the power supply voltage e _uv is short-circuited, causing not only a large loss but also a safety problem. In order to prevent this short circuit, it is necessary to turn off the gate signal of the switching element _SugL , but the sign of the current may change, and a delicate switch operation has been required.

  In this regard, as in the second embodiment, by connecting one parallel capacitor and connecting it to the outside of the switching element, the parallel capacitor is constantly charged and discharged and the voltage also changes due to a change in external voltage. can do. For this reason, the subject which cannot perform charge discharge of the parallel capacitor of the switching element which is OFF which is a subject of patent documents 1 is solved. Further, in preparation for commutation, which is another problem of Patent Document 1, it is not necessary to give a gate signal to the switching element in advance in order to secure a discharge path of the capacitor voltage, so that the complexity of the switch operation is improved. It is safe to use because it does not cause a power supply short circuit even if a power supply code detection error occurs.

  As described above, the bidirectional switch according to the second embodiment does not generate a loss due to a voltage change applied to the bidirectional switch at the time of OFF compared to the bidirectional switch proposed in Patent Application 1, and thus is high. It is efficient, and since it is not necessary to give a gate signal to the switching element in advance in order to secure a capacitor voltage discharge path, the possibility of a power supply short-circuit can be eliminated, so that it is easy to use and safe. Such an effect is the same for the bidirectional switch according to the first embodiment.

(Third embodiment)
FIG. 7 shows a configuration of a three-input one-output leg circuit using the first bidirectional switch. The input circuit w is added to the 2-input 1-output leg circuit shown in FIG. 1 to provide a 3-input 1-output, between the added input terminal w and the output terminal g, as with other terminals, for soft switching. A bidirectional switch S _{wg in} which a capacitor C _soft1 is connected in parallel is inserted. Between the input terminal, connecting the capacitors C _f for filtering the delta connection. One of the bidirectional switches S _ug , S _vg , and S _wg is turned on, and the output current i flows. Therefore, the soft switching condition at the time of commutation is the same as that of the leg circuit of FIG. 1, and when the output current i is a positive current, the switch from the high input potential bidirectional switch to the low input potential bidirectional switch is performed. In the commutation, when the output current i is a negative current, soft switching is realized in the commutation from the low input potential bidirectional switch to the high input potential bidirectional switch.

Note that the bidirectional switch in the leg circuit of FIG. 7 can be replaced with a bidirectional switch by an element having a diode in antiparallel with the switching element shown in FIG. Further, the capacitor C _f between the input terminals can be connected by star connection.

The input of the leg circuit of FIG. 7 is increased to four terminals or more, and a multi-input one-output is provided in which a bidirectional switch in which a soft switching capacitor C _soft1 for soft switching is connected in parallel is connected between the increased terminal and the output terminal. A leg circuit can also be configured. Also in this multi-input one-output leg circuit, when an ON signal is given to one bidirectional switch and the output current i is a positive current, the bidirectional switch with a high input potential is switched to the bidirectional switch with a low input potential. When the output current i is a negative current in the commutation, soft switching is realized in the commutation from the low input potential bidirectional switch to the high input potential bidirectional switch.

(Fourth embodiment)
FIG. 8 is a diagram showing a circuit configuration of a high-frequency isolated AC / DC converter using the leg circuit of the third embodiment. A three-input one-output leg circuit that performs the soft switching operation of FIG. 7 by passing the three-phase voltages e _su , e _sv , and e _sw through the LC filter for suppressing harmonic currents to the power source including the reactor L _f and the capacitance C _f . The matrix converter configuration for AC / AC power conversion is used, and the primary high-frequency voltage v ₁ of the high-frequency transformer _Tr is generated by switching the bidirectional switch S _ug -S _wh . Reactors l ₁ and l ₂ for suppressing current change are connected to the primary side and the secondary side of the high-frequency transformer _Tr , respectively. The secondary high-frequency voltage v ₂ of the high-frequency transformer _Tr is generated by switching of the H-bridge switch S _jp -S _kn connected to the output DC voltage V _dc of the capacitance C. For soft switching, each switch of the primary-side matrix converter, the capacitor C _soft1 in parallel, also, each switch of the secondary side H-bridge, capacitor C _{the soft 2} are respectively connected.

In the circuit shown in FIG. 8, when the leakage inductance of the high-frequency transformer _Tr is large, the reactors l ₁ and l ₂ for suppressing the current change may not be provided.

FIG. 9 shows voltage waveforms of the power supply voltages e _su , e _sv , and e _sw where E is the effective value of the power line voltage. It is assumed that the voltage drop of the reactor L _{f in} FIG. 8 is sufficiently small and the voltage of the capacitance C _f is equal to the power supply voltages e _su , e _sv , e _sw .

FIG. 10 shows each waveform of one cycle of high frequency 2T _s at the power supply voltage e _su > e _sv >0> e _sw at the time point (a) of FIG. 9 with the turns ratio of the high frequency transformer T _r being 1: 1. Yes. That is, this is a case where the sign of the power supply voltage e _sw that maximizes the phase voltage absolute value is negative. The primary voltage command value v ^* ₁ and the secondary voltage command value v ^* ₂ of the high-frequency transformer are provided with a peak value as a square wave of the output DC voltage V _dc , and the electric power passing through the transformer is converted into the primary voltage command value v ^* _1. If it is controlled by the phase angle theta _d of the secondary voltage command value v ^* _2. With increasing phase angle theta _d, the secondary voltage command value v ^* ₂ delay with respect to the primary voltage command value v ^* ₁ increases, the transmission power from the primary side to the secondary side is increased. The primary voltage v ₁ generates a switching pattern such that the average value during the half cycle T _s is equal to the command value v ^* ₁ . The secondary voltage v ₂ energizes the H bridge 180 degrees to generate a square wave voltage having a _peak value V _dc equal to the command value v ^* ₂ . The exciting current is ignored because it is sufficiently small, and the primary and secondary currents i ₁ and i ₂ of the high-frequency transformer have the same waveform.

As shown in FIG. 10, when the power supply voltage is e _su > e _sv >0> e _sw , the minimum value at which the absolute value of the power supply phase voltage is maximized in the positive half cycle T _{s of the} primary voltage v ₁ of the high-frequency transformer. by turning on the bidirectional switch S _wh voltage phase w, h phase that provides the negative potential of the primary voltage v ₁ is constantly connected to the minimum voltage phase w, g phase as a positive potential, bidirectional minimum voltage phase w From the switch S _wg , the bidirectional switch S _ug of the maximum voltage phase u, the bidirectional switch S _vg of the intermediate voltage phase v, and the bidirectional switch S _wg of the minimum voltage phase w are changed. In the negative half cycle T _{s of the} primary voltage v ₁ of the high-frequency transformer, the g phase always turns on the bidirectional switch S _wg of the minimum voltage phase w, and the h phase from the bidirectional switch S _wh of the minimum voltage phase w bidirectional switch _{S uh} maximum voltage phase u, bidirectional switch _{S vh} intermediate voltage phase v, varying the bidirectional switch _{S wh} and on state of the minimum voltage phase w.

A method of generating a voltage waveform of the primary voltage v _{1 having} a small difference from the square wave primary voltage command value v ^* _{1 in} FIG. 10 will be described. Since the primary voltage terminals g and h are respectively connected to the power supply voltages e _su , e _sv , and e _sw by turning on one of the bidirectional switches, the instantaneous voltage of the primary voltage v _{1 is} the voltage between the power supply lines. Appears. From the relationship of power supply voltage e _su > e _sv >0> e _sw , the magnitude relationship of all the line voltages is e _uw > e _vw > e _uv > 0 = e _uu = e _vv = e _ww > e _vu > e _It is obtained that _wv > e _wu . In order to increase the voltage utilization rate, it is desirable to use a high voltage. In the positive half cycle of the primary voltage command value v ^* ₁ , two types of positive voltages e _uw and e _vw are used. Since it is connected to the w phase, the number of times of switching in the w phase is reduced by using e _ww as the zero voltage. Therefore, the h phase is fixed to the minimum voltage phase w of the maximum absolute value of the phase voltage | e _sw | and the voltage phase of the primary voltage v ₁ is approximated to a square so that the g phase is at the beginning and end of the half cycle. In order to generate a zero voltage, it is connected to the minimum voltage phase w, and in the middle of the half cycle, it is connected to the maximum voltage phase u and the intermediate voltage phase v. In the negative half cycle of the primary voltage command value v ^* ₁ , two types of negative large voltages e _wu and e _wv are used, and since both g voltages are connected to the w phase, e _ww is used as a zero voltage. Use to reduce the number of w-phase switching times. Therefore, the g phase is fixed to the minimum voltage phase w of the maximum absolute value | e _sw | of the phase voltage, and the h phase is at the beginning and end of the half cycle in order to make the voltage waveform of the primary voltage v ₁ close to a square. In order to generate a zero voltage, it is connected to the minimum voltage phase w, and in the middle of the half cycle, it is connected to the maximum voltage phase u and the intermediate voltage phase v. Regarding the connection order of the maximum voltage phase u and the intermediate voltage phase v in the positive and negative half cycles of the primary voltage command value v ^* ₁ , it is necessary to consider the order so that soft switching is performed.

As described above, the soft switching condition is that the output current i of the leg circuit is a positive current in the commutation from the bidirectional switch with a high input potential to the bidirectional switch with a low input potential. In the commutation from the bidirectional switch to the bidirectional switch having a high input potential, the output current i of the leg circuit is a negative current. The g-phase output current i _g is in the same direction as the primary current i ₁ and i _g = i ₁ . The h-phase output current i _h is i _h = −i ₁ in the opposite direction to the primary current i ₁ . From FIG. 10, the six-time commutation state of the primary side matrix converter in one cycle 2T _s of the primary voltage v ₁ of the high-frequency transformer satisfies all the soft switching conditions and the soft switching is achieved as shown in the following equation. Yes.

[Formula 2]

Non-Patent Document 1 described above describes soft switching of the secondary side converter, and the principle will be described. FIG. 11 shows a commutation process of soft switching of the secondary side converter. FIG. 5A shows the commutation operation from the j-phase negative switch S _jn to the positive switch S _{jp when the} secondary current i ₂ > 0. In mode 1 before commutation, the secondary current i ₂ of the transformer flows through the switch S _jn, and the parallel capacitor of the switch S _jp accumulates p-side + and transformer-side charges. When the switch S _jn is turned off, zero voltage switching can be realized because the charge of the parallel capacitor is zero. When the switch S _jn is turned off, the mode shifts to mode 2, the secondary current i ₂ is shunted to the two capacitors, the negative capacitor is charged, and the positive capacitor is discharged. After the discharge of the positive capacitor is completed, the mode 3 is entered, and the secondary current i ₂ flows through the diode of the switch S _jp . By applying an ON signal to the switch S _jp during the ON period of the diode, the switch S _jp becomes zero current switching when the secondary current i ₂ changes from positive to negative.

FIG. 11B shows a commutation operation from the j-phase positive switch S _jp to the negative switch S _jn in the secondary current i ₂ <0. In mode 1 before commutation, the secondary current i ₂ of the transformer flows through the switch S _jp, and the parallel capacitor of the switch S _jn stores the charges on the transformer side + and the n side −. When the switch S _jp is turned off, zero voltage switching can be realized because the charge of the parallel capacitor is zero. The switches S _uk off, the process proceeds to mode 2, the secondary current i ₂ is branched into two capacitors, the positive side capacitor is charged, the negative side capacitor is discharged. After the discharge of the negative capacitor is completed, the mode 3 is entered, and the secondary current i ₂ flows through the diode of the switch S _jn . By applying an ON signal to the switch S _jn during the ON period of the diode, the switch S _jn becomes zero current switching when the secondary current i ₂ changes from negative to positive.

The condition of the soft switching of the secondary side converter is that the secondary current is positive (i ₂ > 0) and reverse in the commutation of the switch S _jn → S _{jp from} the negative side switch to the positive side switch in the j phase. In the commutation of the switch S _jp → S _{jn from} the positive side switch to the negative side switch, the secondary current is negative (i ₂ <0). In the k phase, the sign of the secondary current is reversed with that of the j phase. Therefore, the sign of the secondary current is also reversed in the soft switching condition, and the secondary current is commutated from the negative switch to the commutation from the positive switch. The current is negative (i ₂ <0), and the secondary current is positive (i ₂ > 0) in the commutation from the positive switch to the negative switch.

  As shown in FIG. 10, in switching of each switch of the secondary side H-bridge, the soft switching condition is satisfied in all switching as shown in the following formula, and the soft switching is achieved.

[Formula 3]

FIG. 12 shows each waveform of one period 2T _s of a high frequency when the power supply voltage e _su >0> _esv > _esw at the time (b) in FIG. 9. At the time point (b) of FIG. 9, the sign of the power supply voltage e _su at which the phase voltage absolute value is maximum is positive, and the line voltages e _uw and e _uv are the line voltages at the time point (a) of FIG. 9. It is a state equal to e _uw and e _vw . At this time, the primary voltage v ₁ , the secondary voltage v ₂ and the primary / secondary currents i ₁ and i ₂ of the high-frequency transformer of FIGS. 12 and 10 are all equal in waveform. In FIG. 12 and FIG. 10, since the power supply voltage is different, the control of the primary side matrix converter is different, but the control of the secondary side converter is the same.

In FIG. 12, the input phase connected to the g and h phases is different from the input phase of FIG. In the positive half cycle T _{s of the} primary voltage v ₁ of the high-frequency transformer, the bidirectional switch S _ug of the maximum voltage phase u in which the absolute value of the power supply phase voltage is maximized is turned on to be a positive potential of the primary voltage v _1. g phase always connected to the maximum voltage phase u, h phase as a negative potential, the bidirectional switch S _uh maximum voltage phase u, the minimum voltage phase w of the bidirectional switch S _wh, the intermediate voltage phase v bidirectional The switch S _vh and the bidirectional switch S _uh of the maximum voltage phase u are changed to the ON state. In the negative half cycle T _{s of the} primary voltage v ₁ of the high-frequency transformer, the h phase always turns on the bidirectional switch S _uh of the maximum voltage phase u, and the g phase from the bidirectional switch S _ug of the maximum voltage phase u The bidirectional switch S _wg in the minimum voltage phase w, the bidirectional switch S _vg in the intermediate voltage phase v, and the bidirectional switch S _{uh in the} maximum voltage phase u are changed.

As already explained, the soft switching condition is that the output current of the leg circuit is a positive current in the commutation from the high input potential bidirectional switch to the low input potential bidirectional switch. In commutation from a directional switch to a bidirectional switch with a high input potential, the output current of the leg circuit is a negative current. The six-time commutation state of the primary side matrix converter in one cycle 2T _s of the primary voltage v ₁ of the high-frequency transformer in FIG. 12 satisfies all the soft switching conditions and the soft switching is achieved as shown in the following equation. Yes.

[Formula 4]

FIG. 13 shows each waveform of one period 2T _s of the high frequency at the power supply voltage e _su > e _sv >0> e _sw when power is transmitted from the secondary side to the primary side. In contrast to the case where power is sent from the primary side to the secondary side in FIG. 10, the phase angle Θ _d between the primary voltage command value v ^* ₁ and the secondary voltage command value v ^* ₂ is set to a negative value, and the secondary voltage The command value v ^* ₂ is advanced with respect to the primary voltage command value v ^* ₁ . Further, in order to satisfy the soft switching condition, in the positive half cycle T _{s of the} primary voltage v ₁ of the high-frequency transformer, the h phase that is the negative potential of v ₁ always turns on the bidirectional switch _Swh of the minimum voltage phase w. From the bidirectional switch S _wg of the minimum voltage phase w to the bidirectional switch S _vg of the intermediate voltage phase v, the bidirectional switch S _ug of the maximum voltage phase u, and the bidirectional of the minimum voltage phase w. The switch _SWg and the ON state are changed. In the negative half cycle T _{s of the} primary voltage v ₁ of the high-frequency transformer, the g phase always turns on the bidirectional switch S _wg of the minimum voltage phase w, and the h phase from the bidirectional switch S _wh of the minimum voltage phase w bidirectional switch _{S vh} intermediate voltage phase v, bidirectional switch _{S uh} maximum voltage phase u, changing the bidirectional switch _{S wh} and on state of the minimum voltage phase w. Soft switching conditions are satisfied and soft switching is performed for all the primary and secondary switching, as shown in the following formulas 5 and 6.

［式６］

[Formula 5]

[Formula 6]

  Therefore, soft switching is realized by all switching when the direction of power is bidirectional.

In the invention the circuit of FIG. 8, to derive a duty ratio of the switches of the primary side matrix converter for the generation primary voltage waveform v _1. Voltage drop due to input reactor L _f is sufficiently lower than the power supply voltage, the voltage of each phase the capacitor C _f, and equal to the supply voltage determines the duty ratio. The power supply voltages e _su , e _sv , and e _sw are three-phase symmetrical voltages, and are given by the following equations using the line voltage effective value E and the phase angle Θ.

[Formula 7]

The input current command values i ^* _u , i ^* _v and i ^* _w are given by the following equation using the power supply current effective value I.

[Formula 8]

From the equations 7 and 8, the input instantaneous power p ₁ is obtained by the following equation.

[Formula 9]

As described with reference to FIG. 10, the primary voltage command value v ^* ₁ is a square wave voltage having an amplitude V _dc and a period of 2T _s , and here, the primary current i ₁ is in phase with the amplitude I ₁ and the period 2T _s of v ^* _1. It approximates as a square wave current. Since the input instantaneous power p ₁ is equal to the input power of the primary transformer, the following equation is obtained.

[Formula 10]

From Equation 9 and Equation 10, the primary current amplitude I ₁ is obtained by the following equation.

[Formula 11]

The duty ratio d _ug -d _wh of each bidirectional switch S _ug -S _wh of the primary side matrix converter is derived during the half cycle T _s of the high frequency transformer. First, in order to maintain the continuity of the current of the primary current i ₁ , each of the g-phase and h-phase bidirectional switches is always turned on, so the following equation holds for the duty ratio d _ug −d _wh . .

［式１３］

[Formula 12]

[Formula 13]

Following formula as the duty ratio equation for generating an average voltage equal to the primary voltage command value v ^* ₁ between half period T _s can be obtained.

[Formula 14]

Also, the input current command values i ^* _u , i ^* _v , i ^* _w are given by the following equations 15-17.

［式１６］

［式１７］

[Formula 15]

[Formula 16]

[Formula 17]

Here, the duty ratio of FIG. 10 is obtained in which the instantaneous value of the power supply voltage is e _su > e _sv >0> e _sw (Π / 6 <Θ <Π / 3). Regarding the duty ratio of the half cycle T _s of the primary voltage v ^* ₁ = V _dc > 0, since the h-phase always turns on the bidirectional switch _Swh of the minimum voltage phase w, the h-phase duty ratios d _uh , d _vh , D _wh is given by the following equation.

[Formula 18]

The duty ratios d _ug , d _vg , and d _wg are obtained by the following equations 19 to 21 by substituting the equations 18 and i ₁ = I ₁ into the equations 15 to 17 and further substituting the equations 8 and 11. .

［式２０］

［式２１］

[Formula 19]

[Formula 20]

[Formula 21]

  Since the duty ratio can be determined regardless of the power supply current effective value I from Equations 19 to 21, the effective value I can be calculated as an arbitrary value. For example, the duty ratio can be calculated with I = 1.

For the duty ratio of the primary voltage v ^* ₁ = −V _dc <0 half cycle T _s , the g-phase always turns on the bidirectional switch S _wg of the minimum voltage phase w, so the g-phase duty ratios d _ug , d _vg and _dwg are given by the following equations.

[Formula 22]

The duty ratios d _uh , d _vh , and d _wh are obtained by substituting Expression 22 and i ₁ = −I ₁ into Expressions 15 to 17 and further substituting Expression 8 and Expression 11 into the following Expressions 23 to 25: It is done.

［式２４］

［式２５］

[Formula 23]

[Formula 24]

[Formula 25]

The duty ratio of the half cycle T _s of the primary voltage v ^* ₁ = −V _dc <0 is obtained by switching the duty ratio of the h phase and the g phase of the half cycle T _s of the primary voltage v ^* ₁ = V _dc > 0. .

As shown in FIG. 10, the secondary voltage v ₂ outputs a square wave voltage whose amplitude is the DC voltage V _dc . Accordingly, the duty ratios of the switches S _jp -S _kn are all set to 0.5, and in order to output the positive voltage V _dc , S _jp and S _kn are simultaneously turned on and the negative voltage −V _dc is output. , S _jn and S _kp are simultaneously turned on. As shown in FIG. 10, the secondary voltage v ₂ is controlled by being delayed by the phase difference Θ _{d with} respect to the primary voltage v ₁ .

FIG. 14 shows a method of generating each gate signal in FIG. The magnitude relationship between the sawtooth wave that changes from the current −I ₁ to I _{1 in} a half cycle of the primary voltage v ^* ₁ > 0 and the comparison values i ^* _w , i ^* _u− i ^* _v , and −i ^* _w is compared. Thus, the switching operation timing of the g-phase bidirectional switch S _ug -S _wg of the primary side converter is determined. Since the bidirectional switch S _ug is turned on from i ^* _w to i ^* _u− i ^* _v , the duty ratio d _ug is obtained by the following equation and equal to the equation 19.

[Formula 26]

The bidirectional switch S _vg is turned on from i ^* _u −i ^* _v to −i ^* _w , and the bidirectional switch S _wg is turned on from −I ₁ to i ^* _W and −i ^* _w to I ₁ , respectively. The duty ratios d _vg and d _wg are obtained by the following expressions 27 and 28, and are equal to the expressions 20 and 21, respectively.

［式２８］

[Formula 27]

[Formula 28]

For the h-phase switch S _uh -S _wh , only the bidirectional switch S _wh is turned on as shown in Expression 18.

In order to adjust the power passing through the high-frequency transformer, a current comparison value i ^* _θ corresponding to the phase difference Θ _d between the primary voltage and the secondary voltage is calculated by the following equation, and the timing of the phase difference Θ _d is compared with the sawtooth wave. It has occurred.

[Formula 29]

In the half cycle of the primary voltage v ^* ₁ <0, the on-timing of the switches of the h-phase, the g-phase, and the j-phase and the k-phase in the half cycle of the primary voltage v ^* ₁ = V _dc > 0 is changed. A signal is obtained.

FIG. 15 shows the generation timing of each gate signal for one cycle of the power supply. Even if the magnitude relationship among the power supply voltages e _su , e _sv , and e _sw changes, a gate signal can be generated similarly. In FIG. 15, the input current waveform _iu is shown with the transformer primary current i ₁ as a square wave current having an amplitude I ₁ . The input current waveform i _u has a fundamental wave component including a high frequency component of the switching frequency. The switching frequency component is removed by the input LC filter, and the power supply current has an approximately sinusoidal waveform. The high-frequency transformer generates a primary voltage v ₁ and a secondary voltage v ₂ as expected.

(Experimental example 1)
FIG. 16 is a diagram showing the configuration of the experimental system of this experimental example. Table 1 shows the specifications of the experimental system. As the power source, a three-phase AC power source with an effective line voltage value E = 200V and a frequency of 60 Hz was used, the command value of the load voltage V _dc was 230V, and the load power P _out = 1000W. The reactors l ₁ and l ₂ connected in series to the transformer were both externally connected with a 0.175 mH reactor, and the frequency of the high-frequency transformer was set to 10 kHz. It was also connected a parallel capacitor _C soft1 = 3nF of the switches of the primary side matrix converter for soft switching, the parallel capacitor _C the soft 2 = 5 nF for each switch in the secondary-side converter, respectively. As the controller, a digital signal processor (DSP) was used to detect the power line voltages e _uv and e _vw , the primary current i ₁ and the load voltage V _dc, and calculate the duty ratio and phase difference Θ _d of each switch. Based on each duty ratio, each switching signal was generated using a field-programmable gate array (FPGA).

[Table 1]

FIG. 17 shows an experimental waveform obtained in this experimental example. Each waveform is, from the top, the power supply voltage e _su , the power supply current i _su , the input current i _u , the transformer primary voltage v ₁ , the secondary voltage v ₂ , the primary current i ₁ , and the load voltage V _dc . The input current i _u is controlled to a power factor 1 with a power factor angle command value φ ^* = 0 rad, and includes a 20 kHz component due to switching. A sinusoidal power supply current i _su is obtained by _{passing the} input current i _u through the input LC filter. The power supply current i _su is advanced with respect to the power supply voltage because the 60 Hz advance current flowing from the power supply to the LC filter is superimposed. The low-frequency distortion of the power source current i _su is due to the approximation of the primary current i ₁ as a square wave current in the duty ratio derivation. A high frequency of 10 kHz was obtained as the primary / secondary voltage and primary current of the high frequency transformer. The load voltage V _dc was controlled to 230 V according to the command value.

FIG. 18 is an enlarged waveform of the primary and secondary voltages v ₁ and v ₂ and the primary current i ₁ of the high-frequency transformer. In the primary side matrix converter, as shown in Equation 2, when the primary voltage v ₁ ≧ 0 in which g-phase commutation occurs, the primary current i ₁ is negative when v ₁ changes from a low voltage to a high voltage. In the change from the high voltage to the low voltage, the primary current i ₁ is positive. In the primary voltage v ₁ ≦ 0 at which h-phase commutation occurs, the primary current i ₁ is positive when v ₁ changes from a high voltage to a low voltage, and the primary current i ₁ changes when the change from a low voltage to a high voltage. ₁ was negative and satisfied the soft switching condition. Also in the secondary converter, as shown in Expression 3, in the commutation of the switches S _jn → S _jp and S _kp → S _{kn in which} the secondary voltage v ₂ changes from negative to positive, the secondary current i ₂ (i ₁ ) Is positive. Conversely, when the secondary voltage v ₂ changes from positive to negative, the secondary current i ₂ (i ₁ ) is negative and the soft switching condition is satisfied.

FIGS. 19 and 20 show the waveforms of the switch current and voltage during commutation of the primary side bidirectional switch S _wg → S _ug and the secondary side bidirectional switch S _jn → S _jp , respectively, as shown in FIG. In soft switching, and in hard switching where no parallel capacitor is connected to the bidirectional switch. In both FIG. 19 and FIG. 20, in the soft switching of FIG. (A), compared with the hard switching of FIG. (B), the overlapping portion of the current and voltage at the time of switch switching is reduced, and soft switching can be realized. It was.

(Experimental example 2)
In this experimental example, the switching loss was measured using a digital oscilloscope (manufactured by Textronix, DPO7054) in order to confirm the effect of reducing the switching loss by soft switching. The experimental conditions were the same as in Table 1. In the case of soft switching, a capacitor was connected in parallel to the bidirectional switch, and in the case of hard switching, the measurement was performed without connecting the parallel capacitor. Table 2 shows the measurement results. When hard switching was used, the switching losses in the primary and secondary converters were 3.25 W and 8.04 W, respectively, for a total of 11.29 W. On the other hand, when soft switching was used, the switching losses in the primary side converter and the secondary side converter were 0.88 W and 1.55 W, respectively, and the total loss was 2.43 W. Thus, it was found that the switching loss can be reduced to about 1/5 by using soft switching as compared with hard switching.

[Table 2]

(Fifth embodiment)
FIG. 21 is a diagram showing a circuit configuration of a non-insulated power converter in which the high-frequency transformer circuit of the isolated AC / DC power converter shown in FIG. 8 is replaced with an inductor. As shown in FIG. 21, the three-phase voltages e _su , e _sv , e _sw are passed through a LC filter for suppressing harmonic current to the power source consisting of the reactor L _f and the capacitance C _f, and the three-input one-output shown in FIG. A three-phase voltage is connected to each of the first coupling point a and the third coupling point c using a leg circuit to form a matrix converter configuration for AC / AC power conversion, and the switching is performed by the bidirectional switch S _ug -S _wh . A voltage v ₁ between one coupling point a and a third coupling point c is generated. The first coupling point a and the second coupling point b are connected by an inductor L for suppressing a current change. The voltage v ₂ between the second coupling point b and the third coupling point c is generated by switching of the H-bridge switch S _jp -S _kn connected to the output DC voltage V _dc of the capacitance C. For soft switching, each switch of the primary-side matrix converter, the capacitor C _soft1 in parallel, also, each switch of the secondary side H-bridge, capacitor C _{the soft 2} are respectively connected. The transfer characteristics of the primary and secondary 4 terminals g, h, j, and k in both the circuits of FIG. 21 and FIG. 8 are inductive and are the same including the switching pattern, each duty ratio, and the control method. Switching can be realized and the AC side current can be made close to a sine wave.

(Sixth embodiment)
FIG. 22 is a diagram illustrating a circuit configuration of a power converter in which the high-frequency transformer circuit of the isolated AC / DC power converter illustrated in FIG. 8 is replaced with a combined wireless power feeding system. Primary terminals g, and connect the power factor correction capacitor C _p and the power transmission coil between h, is similarly configured whereby a power factor correction capacitor C _p and the power transmission coil between secondary terminal j, k. The transfer characteristics of the primary and secondary four terminals g, h, j, and k in both the circuits of FIG. 22 and FIG. 8 are inductive, and are the same including the switching pattern, each duty ratio, and the control method. Switching can be realized and the AC side current can be made close to a sine wave.

  8 and 22 and the control thereof can be applied to a circuit in which the transfer characteristics of primary and secondary 4 terminals g, h, j, and k have inductive characteristics, and soft switching is realized in all switching elements. In addition, the AC side current can be made closer to a sine wave.

(Seventh embodiment)
FIG. 23 is a diagram showing a circuit configuration of an isolated AC / AC power converter in which the secondary side of the isolated AC / DC power converter shown in FIG. 8 is connected to the same matrix converter as the primary side and a three-phase power source. .

In FIG. 24, the turn ratio of the high-frequency transformer T _r is 1: 1, and the primary power supply voltage e _su > _esv >0> _esw and the secondary power supply voltage e _sr > _{es s} >0> _est are It shows each waveform of one period 2T _s high frequency during power transmission to the next side. The primary voltage command value v ^* ₁ and the secondary voltage command value v ^* ₂ of the high-frequency transformer are given as square waves having the same peak value, and the power passing through the transformer is converted into the primary voltage command value v ^* ₁ and the secondary voltage command value. It is controlled by the phase angle Θ _d with v ^* ₂ . The switching pattern is generated so that the average value of the primary and secondary voltages v ₁ and v _{2 during} the half period T _s is equal to the command values v ^* ₁ and v ^* ₂ .

Primary voltage v _1, as shown in FIG. 24 similarly to FIG. 10, both of the positive half period T _s of the high-frequency transformer primary voltage v _1, a negative potential of v ₁ h phase minimum voltage phase w on the counter switch _{S wh} constantly, g phase that provides the positive potential, the bidirectional switch _{S wg} minimum voltage phase w, bidirectional switch _{S ug} of maximum voltage phase u, bidirectional switch _{S vg} intermediate voltage phase v , The bidirectional switch _Swg of the minimum voltage phase w and the on state are changed. In the negative half cycle T _{s of the} primary voltage v ₁ of the high-frequency transformer, the g phase always turns on the bidirectional switch S _wg of the minimum voltage phase w, and the h phase from the bidirectional switch S _wh of the minimum voltage phase w bidirectional switch _{S uh} maximum voltage phase u, bidirectional switch _{S vh} intermediate voltage phase v, varying the bidirectional switch _{S wh} and on state of the minimum voltage phase w.

On the secondary side, since the direction of the current i ₂ when viewed from the converter is opposite to the primary current i ₁ , the switching order is switched for soft switching. In the positive half cycle T _{s of the} secondary voltage v ₂ of the high-frequency transformer, the k phase that is the negative potential of v ₂ always turns on the bidirectional switch S _tk of the minimum voltage phase t, and the j phase that is the positive potential is from the bidirectional switch _{S tj} minimum voltage phase t, bidirectional switch _{S sj} intermediate voltage phase s, bidirectional switch Srj maximum voltage phase r, changing the bidirectional switch _{S tj} and on state of the minimum voltage phase t. In the negative half cycle T _{s of the} secondary voltage v ₂ of the high-frequency transformer, the j-phase always turns on the bidirectional switch S _tj of the minimum voltage phase t, and the k-phase starts from the bidirectional switch S _tk of the minimum voltage phase t. The ON state of the bidirectional switch S _sk of the intermediate voltage phase s, the bidirectional switch S _rk of the maximum voltage phase r, and the bidirectional switch S _tk of the minimum voltage phase t is changed.

  As can be seen from the current state in FIG. 24, the soft switching condition is satisfied in all switching. That is, in the commutation from the high input potential bidirectional switch to the low input potential bidirectional switch, the output current of the leg circuit is a positive current, and the low input potential bidirectional switch to the high input potential bidirectional switch. In the commutation, the output current of the leg circuit is a negative current.

  Note that the duty ratio of the matrix converter in the fourth embodiment can be used as the duty ratio of each switch in this control.

(Eighth embodiment)
FIG. 25 is a diagram showing a circuit configuration in which the high-frequency transformer circuit of the isolated AC / AC power converter shown in FIG. 23 is replaced with a combined wireless power feeding system. Primary terminals g, and connect the power factor correction capacitor C _p and the power transmission coil between h, is similarly configured whereby a power factor correction capacitor C _p and the power transmission coil between secondary terminal j, k. The transfer characteristics of the primary and secondary 4 terminals g, h, j, and k in both the circuits of FIG. 25 and FIG. 23 are inductive and are the same including the switching pattern, each duty ratio, and the control method. Switching can be realized and the AC side current can be made close to a sine wave.

  23 and 25 and the control thereof can be applied to a circuit in which the transfer characteristics of primary and secondary four terminals g, h, j, and k have inductive characteristics, and soft switching is realized in all switching elements. In addition, the AC side current can be made closer to a sine wave.

Claims (8)

A primary side circuit and a secondary side circuit via a transfer circuit having inductive transfer characteristics having first and second connection terminals on the primary side and third and fourth connection terminals on the secondary side Is a power converter connected in an electric circuit,
At least the primary-side circuit includes two reverse blocking switching elements connected in reverse parallel and one soft switching capacitor connected in parallel with the switching element connected in reverse parallel A matrix converter including a switch circuit is connected,
The power converter, when each phase terminal of a three-phase AC power supply is connected to each of the input terminals to the matrix converter,
In order from the largest absolute value of the potential, the x phase, the y phase, and the z phase are set, and the first half of the control cycle is the first half cycle, and the second half is the second half cycle.
By control signal,
When the x-phase potential is positive,
In the first half cycle, the bidirectional switch circuit between the first connection terminal and the x phase is fixed in an ON state,
In the second half cycle, the bidirectional switch circuit between the second connection terminal and the x-phase is fixed in an ON state,
When the x-phase potential is negative,
In the first half cycle, the bidirectional switch circuit between the second connection terminal and the x phase is fixed in an ON state,
In the second half cycle, the bidirectional switch circuit between the first connection terminal and the x phase is fixed in an ON state,
The other connection terminals of the first connection terminal and the second connection terminal are:
During power transmission from the primary side to the secondary side,
From the bidirectional switch circuit between the other connection terminal and the x phase, commutation is performed in all three phases in the order of the bidirectional switch circuit between the y phase, the z phase, and the x phase,
During power transmission from the secondary side to the primary side,
By being controlled so as to perform commutation in all three phases in the order of the bidirectional switch circuit between the other connection terminal and the x-phase in the order of the z-phase, the y-phase, and the x-phase bidirectional switch circuit, A power converter configured to switch a commutation operation of the bidirectional switch circuit according to a power transmission direction. A primary side circuit and a secondary side circuit via a transfer circuit having inductive transfer characteristics having first and second connection terminals on the primary side and third and fourth connection terminals on the secondary side Is a power converter connected in an electric circuit,
At least the circuit on the primary side includes two switching elements with freewheeling diodes connected in reverse series and one soft switching capacitor connected in parallel to both ends of the switching elements connected in reverse series. A matrix converter including a bidirectional switch circuit is connected,
The power converter, when each phase terminal of a three-phase AC power supply is connected to each of the input terminals to the matrix converter,
In order from the largest absolute value of the potential, the x phase, the y phase, and the z phase are set, and the first half of the control cycle is the first half cycle, and the second half is the second half cycle.
By control signal,
When the x-phase potential is positive,
In the first half cycle, the bidirectional switch circuit between the first connection terminal and the x phase is fixed in an ON state,
In the second half cycle, the bidirectional switch circuit between the second connection terminal and the x-phase is fixed in an ON state,
When the x-phase potential is negative,
In the first half cycle, the bidirectional switch circuit between the second connection terminal and the x phase is fixed in an ON state,
In the second half cycle, the bidirectional switch circuit between the first connection terminal and the x phase is fixed in an ON state,
The other connection terminals of the first connection terminal and the second connection terminal are:
During power transmission from the primary side to the secondary side,
From the bidirectional switch circuit between the other connection terminal and the x phase, commutation is performed in all three phases in the order of the bidirectional switch circuit between the y phase, the z phase, and the x phase,
During power transmission from the secondary side to the primary side,
By being controlled so as to perform commutation in all three phases in the order of the bidirectional switch circuit between the other connection terminal and the x-phase in the order of the z-phase, the y-phase, and the x-phase bidirectional switch circuit, A power converter configured to switch a commutation operation of the bidirectional switch circuit according to a power transmission direction. A positive electrode terminal and a negative electrode terminal connected to a DC power source or a DC load in the secondary circuit;
The transmission circuit includes the third connection terminal and the positive terminal, the third connection terminal and the negative terminal, the fourth connection terminal and the positive terminal, the fourth connection terminal and the negative terminal, The power converter according to claim 1 or 2, wherein the switching element with a diode is connected by a circuit in which a soft switching capacitor is connected in parallel.   The transmission circuit includes any one of a high-frequency transformer, a non-insulated power converter including an inductor between the first connection terminal and the third connection terminal, and a combined wireless power feeding system. The power converter according to any one of claims 1 to 3.   3. The matrix converter including a bidirectional switch circuit is connected to the secondary side circuit, and a three-phase AC load or a three-phase AC power source is connected to the secondary side circuit. The power converter described. A method for controlling a power converter according to any one of claims 1 to 5,
A method for controlling a power converter configured to switch a commutation operation of the bidirectional switch circuit according to a power transmission direction according to the control signal. A method for controlling a power converter according to any one of claims 1 to 5,
When the output current of the matrix converter provided in the circuit on the primary side is positive, the input has a potential lower than the potential of the input terminal to which the bidirectional switch circuit that is turned on in the matrix converter is connected. Commutation to the bidirectional switch circuit connected to the terminal,
When the output current of the matrix converter is negative, the bidirectional switch circuit connected to the input terminal having a higher potential than the input terminal connected to the bidirectional switch circuit that is turned on in the matrix converter A method for controlling a power converter, characterized in that commutation is performed. A method for controlling a power converter according to claim 5,
The bidirectional switch circuit included in the secondary side circuit includes:
During power transmission from the primary side to the secondary side, the phase of the secondary side voltage is controlled to be delayed with respect to the primary side voltage of the transmission circuit,
The power converter is controlled so that a phase of the secondary side voltage advances with respect to the primary side voltage of the transmission circuit during power transmission from the secondary side to the primary side Control method.

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