JP2013252018A - Power transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that the circuit scale increases or the switching control objects increase, when a step-up chopper circuit is provided so as to transmit power from one of the first and second coils of a transformer connected with the lower voltage of a DC voltage source to the other connected with the higher voltage.SOLUTION: A first capacitor Ci is connected through a first full-bridge circuit FB1 with the first coil w1 of a transformer T, and a second capacitor Co is connected through a second full-bridge circuit FB2 with the second coil w2 of a transformer T. The leakage inductor of the transformer T is equivalent to provision of an inductor 12 between the first full-bridge circuit FB1 and second full-bridge circuit FB2. When transmitting power from the second coil w2 side to the first coil w1 side, the power is stored temporarily in the inductor 12.

Description

  The present invention relates to a power transmission device that includes a transformer and has a boosting function when transmitting power.

  As this type of power transmission device, for example, as described in Patent Document 1 below, a device including a full bridge circuit and a boost chopper circuit between a secondary coil of a transformer and an in-vehicle battery has been proposed. Yes. Thereby, even if it is a case where the voltage of a vehicle-mounted battery is lower than the voltage of the system power supply connected to a primary side coil, the electric power of a vehicle-mounted battery can be supplied to a system power supply.

JP 2008-312395 A

  However, in the case of the above-described device, it is necessary to provide a step-up chopper circuit on the secondary coil side of the transformer in order to transmit power to the system power supply, which increases the number of parts.

  The present invention has been made in the process of solving the above-described problems, and an object of the present invention is to provide a new power transmission device having a step-up function when transmitting power with a transformer.

  Hereinafter, means for solving the above-described problems and the operation and effect thereof will be described.

  The invention according to claim 1 is a first coil (w1), a first bridge circuit (FB1) connected to the first coil, a second coil (w2) magnetically coupled to the first coil, and A second bridge circuit (FB2) connected to the second coil, and an electric path between the first bridge circuit and the second bridge circuit includes an electric current flowing through the first coil and the second coil. Inductance is set so that the stored energy can be increased or decreased in accordance with the increase or decrease, and the first bridge circuit controls each of the one terminal and the other terminal of the first coil by the leg. The second bridge circuit is connected to each of a positive terminal and a negative terminal of the bridge circuit, and the second bridge circuit has one leg of the second coil and the other depending on the leg. Are connected to the positive-side terminal and the negative-side terminal of the second bridge circuit, respectively, and applied to the coils connected to the first bridge circuit and the second bridge circuit. From the low voltage side bridge circuit (FB2) having a smaller value divided by the number of turns of the coil to the high voltage side bridge circuit (FB1) having a larger value, the first coil and the first coil Of the two coils, the first voltage is transmitted through a low voltage coil that is a coil connected to the low voltage bridge circuit and a high voltage coil that is magnetically coupled to the low voltage coil. A boost processing means (20) for operating a bridge circuit and the second bridge circuit, wherein the boost processing means is connected to the positive side of the high voltage side bridge circuit; By closing a detour path to which both ends of the high-voltage side coil are connected only through a path connected to one of the child and the negative electrode side terminal, the first bridge circuit and the first An accumulation process for gradually increasing the current in the electric path between the two bridge circuits to accumulate energy in the electric path, and opening the detour path so that the energy accumulated by the accumulation process is changed to the high-voltage side bridge And a step-up process for outputting to the outside of the high-voltage side bridge circuit via a positive terminal and a negative terminal of the circuit.

  In the said invention, energy can be stored in the electrical path between the 1st bridge circuit and the 2nd bridge circuit by constituting a detour path. For this reason, it is possible to perform a boosting process, and as a result, energy can be transmitted from the low voltage side bridge circuit to the high voltage side bridge circuit. Moreover, it is not necessary to provide a booster circuit or the like for this processing.

  In addition, about the expansion of the concept regarding the following typical embodiment concerning this invention, it describes in the column of "other embodiment" after typical embodiment.

1 is a system configuration diagram according to a first embodiment. FIG. The figure which shows the structure of the trans | transformer concerning the embodiment. The time chart which shows the switching operation method at the time of the electric power input concerning the embodiment. The circuit diagram which shows the electric power input process concerning the embodiment. The time chart which shows the switching operation method at the time of the electric power output concerning the embodiment. The circuit diagram which shows the electric power output process concerning the embodiment. The time chart which shows the electric power output process aspect concerning the embodiment. The system block diagram concerning 2nd Embodiment. The time chart which shows the switching operation method at the time of the electric power input concerning the embodiment. The circuit diagram which shows the electric power input process concerning the embodiment. The time chart which shows the switching operation method at the time of the electric power output concerning the embodiment. The circuit diagram which shows the electric power output process concerning the embodiment. The circuit diagram which shows the electric power output process concerning the embodiment. The time chart which shows the electric power output process aspect concerning the embodiment. The system block diagram concerning 3rd Embodiment. The time chart which shows the switching operation method concerning the embodiment. The system block diagram concerning 4th Embodiment. The time chart which shows the switching operation method concerning the embodiment. The system block diagram concerning 5th Embodiment.

<First Embodiment>
Hereinafter, a first embodiment in which a power transmission device according to the present invention is applied to an in-vehicle power transmission device will be described with reference to the drawings.

  The converter CNV shown in FIG. 1 is mounted on an in-vehicle power transmission device. The converter CNV has a function of supplying power to the second capacitor Co with respect to the first capacitor Ci serving as an output unit of a device (not shown) that uses power from a commercial power supply outside the vehicle as a predetermined DC voltage. The converter CNV also has a function of transmitting the power of the second capacitor Co to the first capacitor Ci. Specifically, the converter CNV is an insulating converter, and is configured to include a transformer T.

  A first full bridge circuit FB1 is connected to the first coil w1 of the transformer T. The first full bridge circuit FB1 includes a series connection body (leg) of a switching element S1 and a switching element S2 connected in parallel (short-circuit connection) between both electrodes of the first capacitor Ci, and a series of the switching element S3 and the switching element S4. And a connecting body (leg). A first coil w1 of the transformer T is connected between a connection point between the switching element S1 and the switching element S2 and a connection point between the switching element S3 and the switching element S4. Here, the positive terminal Tip1 of the first full bridge circuit FB1 is a connection point between the switching elements S1 and S3, and the negative terminal Tin1 is a connection point between the switching elements S2 and S4.

  In the present embodiment, N-channel MOS field effect transistors are illustrated as the switching elements S1 to S4. In the drawing, each of the diodes D1 to D4 is a body diode of each of the switching elements S1 to S4.

  A second full bridge circuit FB2 is connected to the second coil w2 of the transformer T. The second full bridge circuit FB2 includes a series connection body (leg) of a switching element Sa and a switching element Sb connected in parallel (short circuit connection) between both electrodes of the second capacitor Co, and a series of the switching element Sc and the switching element Sd. And a connecting body (leg). A second coil w2 of the transformer T is connected between a connection point between the switching element Sa and the switching element Sb and a connection point between the switching element Sc and the switching element Sd. Here, the positive terminal Tip2 of the second full bridge circuit FB2 is a connection point between the switching elements Sa and Sc, and the negative terminal Tin2 is a connection point between the switching elements Sb and Sd.

  In the present embodiment, N-channel MOS field effect transistors are illustrated as the switching elements Sa to Sd. In the drawing, each of the diodes Da to Dd is a body diode of each of the switching elements Sa to Sd.

  A load 14 is connected in parallel to the second capacitor Co. The load 14 includes an energy storage means (battery) of a rotating machine as a vehicle-mounted main machine. In the present embodiment, it is assumed that the voltage on the load 14 side (terminal voltage) is lower than the voltage Vi on the first capacitor Ci side. In particular, in the present embodiment, it is assumed that the relationship of “Vi / N1> Vo / N2” is established when the numbers of turns N1 and N2 of the first coil w1 and the second coil w2 are used.

  In the figure, an inductor l2 is described between the second coil w2 and the second full bridge circuit FB2. As shown in FIG. 2, this is an equivalent circuit representation of a leakage inductor generated by increasing the gap between the magnetic core 11 of the transformer T and the first coil w1 and the second coil w2. As an equivalent circuit expression, the inductor 12 may be described between the first coil w1 and the first full bridge circuit FB1.

The control device 20 outputs the operation signals ms1 to ms4 and the operation signals msa to msd to the switching elements S1 to S4 and the switching elements Sa to Sd, respectively, so that the first coil w1 and the second coil are output. Power transmission processing is performed from one side of w2 to the other side and from the other side to the other side. In the following, “charging process from the external commercial power source to the in-vehicle battery side” will be described, and then “power output processing from the in-vehicle battery side to the external commercial power source” will be described.
“Charging process from external commercial power source to in-vehicle battery”
This is a power transmission process from the first coil w1 side to the second coil w2 side. Specifically, as shown in FIG. 3, the operation signals m1, m4 and the operation signals m2, m3 are the same signal, and the operation signals m1, m4 and the operation signals m2, m3 The phase is shifted by π. According to the operation of the switching elements S1 to S4 by the operation signals ms1 to ms4 shown in FIG. 3, the first full bridge circuit FB1 is converted into a DC / AC conversion means for converting a DC voltage (voltage of the first capacitor Ci) into an AC voltage. can do. At this time, for the second full bridge circuit FB2, the diodes Da to Db function as a full-wave rectifier circuit.

  Hereinafter, with reference to FIG. 4, a qualitative explanation will be given regarding the power transmission processing from the first coil w1 side to the second coil w2 side.

  FIG. 4A shows a case where the switching elements S1 and S4 are switched from the off state to the on state. As shown in the figure, in this case, the applied voltage Vw1 of the first coil w1 has an absolute value that is the voltage Vi of the first capacitor Ci and is negative. A current flows through a closed loop path including the first capacitor Ci, the switching element S1, the first coil w1, and the switching element S4. On the other hand, the applied voltage Vw2 of the second coil w2 is a voltage “−n · Vi” having a magnitude corresponding to the ratio (turn ratio n) between the number of turns N1 of the first coil w1 and the number of turns N2 of the second coil w2. It becomes. Thereby, a current flows through a path including the second coil w2, the diode Dc, the second capacitor Co, and the diode Db.

  FIG. 4B shows a case where the switching elements S1 and S4 are switched to the off state. In this case, a current flows through a closed loop path including the inductor 12, the second coil w2, the diode Dc, the second capacitor Co, and the diode Db in order to release the energy stored in the inductor 12. Since the current flows through the second coil w2, the current also flows through the first coil w1 through a closed loop path including the first coil w1, the diode D3, the first capacitor Ci, and the diode D2. When a current flows through the path, the applied voltage Vw1 of the first coil w1 becomes “Vi” having a polarity opposite to that of FIG. As a result, the applied voltage Vw2 of the second coil w2 becomes “n · Vi” having the opposite polarity to that of FIG. For this reason, the voltage VL applied to the inductor 12 becomes “−n · Vi−Vo”, and the current flowing through the inductor 12 gradually decreases according to the absolute value of the value obtained by dividing the voltage VL by the inductance of the inductor 12.

  FIG. 4C shows a state in which the current flowing through the first coil w1, the second coil w2, and the inductor 12 is gradually reduced to zero.

  In addition, after the state of FIG.4 (c), on-off operation of switching element S2, S3 is performed in the way illustrated about switching element S1, S4 in FIG.

  As described above, in the present embodiment, the reverse current is not applied to the diodes Db and Dc (Da, Dd) of the second full bridge circuit FB2 during the period in which the forward current flows. It can be avoided. Thereby, the surge voltage can be suitably reduced when switching the switching states of the switching elements S1 to S4. This is made possible by the following two settings. In the first setting, when the inductor 12 is provided between the first full bridge circuit FB1 and the second full bridge circuit FB2, and the application of the voltage that gradually increases the current flowing through the inductor 12 is stopped, the voltage that is gradually decreased is set. A closed loop path to be applied (FIG. 4B) is configured. The second setting is that there is no branch path in the electrical path connecting the positive terminal Tip2 and the negative terminal Tin2 of the second full bridge circuit FB2 and the second capacitor Co.

  That is, in this case, the diodes Da, Dd (Db, Dc) are not turned on until the forward current flowing through the diodes Db, Dc (Da, Dd) gradually decreases to zero. For this reason, it is possible to avoid a situation in which a recovery current flows, and thus it is possible to avoid occurrence of a surge voltage when switching elements S1, S4 (S2, S3) are turned on.

  Further, by providing the inductor 12, when the switching elements S1, S4 (S2, S3) are switched to the on state, the rate of increase of the current flowing through them can be limited. Switching loss can also be reduced.

  As shown in FIG. 1, in the present embodiment, the on-time time ratio D with respect to the on / off period T of the switching elements S1, S4 (S2, S3) is set to the output voltage (voltage Vo) of the converter CNV. The first operation amount is used. Here, the duty ratio D is variably set according to the output voltage Io of the converter CNV in addition to the charging voltage (voltage Vi) of the first capacitor Ci and the voltage Vo of the second capacitor Co. Specifically, even if the voltage Vi and the voltage Vo are the same, the duty ratio D is set to a larger value as the current Io increases. Thus, when the voltage Vi and the voltage Vo are the same, the duty ratio D depends on the output current Io is one of the characteristics of the converter CNV according to the present embodiment. Furthermore, in this embodiment, the switching frequency f is the second manipulated variable of the voltage Vo.

“Processing of power output from in-vehicle battery to external commercial power supply”
This is a power transmission process from the second coil w2 side to the first coil w1 side. Here, as shown in FIG. 5, the operation signals msa, msd and the operation signals msb, msc are the same signal, and the operation signals msa, msd and the operation signals msb, msc The phase is shifted by π. Thereby, the second full bridge circuit FB2 can be used as a DC / AC converting means for converting a DC voltage (voltage of the second capacitor Co) into an AC voltage.

  Further, the operation signal ms4 is switched to the on operation command in synchronization with the switching of the operation signals msa and msd to the on operation command, and the operation signal ms2 is turned on in synchronization with the switching of the operation signals msb and msc to the on operation command. Switch to command. This is a process for storing electrical energy in the inductor 12.

  Hereinafter, with reference to FIG. 6, a qualitative explanation will be given regarding the power transmission processing from the second coil w2 side to the first coil w1 side.

  FIG. 6A shows a state where the switching elements Sa, Sd, S4 are switched to the on state. In this case, on the second coil w2 side, a current flows through a loop path including the second capacitor Co, the switching element Sa, the inductor 12, the second coil w2, and the switching element Sd.

  On the other hand, on the first coil w1 side, a current flows through a loop path including the switching element S4, the diode D2, and the first coil w1. This loop path is a path that connects both ends of the first coil w1 only through the path on the negative terminal Tin side of the positive terminal Tip1 and the negative terminal Tin1 of the full bridge circuit FB1. This path is a bypass path that bypasses the first capacitor Ci and connects both ends of the first coil w1 with a low voltage.

  Here, the voltage Vw1 of the first coil w1 is zero (strictly, it is about the voltage drop amount of the diode D2 and the switching element S4). For this reason, the voltage Vw2 of the second coil w2 can also be regarded as zero. Therefore, the voltage VLs applied to the inductor 12 can be regarded as the voltage Vo of the second capacitor Co, and the current flowing through the inductor 12 gradually increases in proportion to the voltage VLs. Thereby, the magnetic energy stored in the inductor 12 also increases gradually.

  FIG. 6B shows a state in which the switching element S4 is switched to the off state. In this case, until the magnetic energy stored in the inductor 12 becomes zero, a current flows through the inductor 12, and a current also flows through the second coil w2. When a current flows through the second coil w2, a current also flows through the first coil w1 magnetically coupled to the second coil w2 according to Ampere's law. This current flows through a loop path including the first coil w1, the diode D3, the first capacitor Ci, and the diode D2. This process is a process in which the electric energy of the second capacitor Co is charged to the first capacitor Ci having a higher charging voltage than the second capacitor Co, and is a boosting process. At this time, since the voltage Vw2 of the second coil w2 becomes “n · Vi”, the voltage VLs of the inductor 12 becomes “Vo−n · Vin <0”, and the current flowing through the inductor 12 gradually decreases.

  FIG. 6C shows a state where the current flowing through the inductor 12 becomes zero. In the state of FIG. 6C, the switching elements Sb, Sc, and S2 are switched to the on state in the manner of the process shown in FIG.

  As described above, since the switching elements Sb, Sc, and S2 (Sa, Sd, and S4) are switched to the on state after the current flowing through the inductor 12 becomes zero, it is possible to reduce the loss accompanying switching of the switching state.

  FIG. 7 shows transitions of various state quantities associated with power transmission processing from the second coil w2 side to the first coil w1 side.

  Hereinafter, some of the effects according to the present embodiment will be described.

  (1) The inductor 12 is provided between the first full bridge circuit FB1 and the second full bridge circuit FB2. As a result, when power is transmitted from the low voltage side coil (second coil w2) side to the high voltage side coil (first coil w1) side, the magnetic energy is temporarily stored in the inductor 12, thereby performing the boosting process. it can.

  (2) In the state where the current flowing through the inductor 12 gradually increases (FIG. 6A), the application of the voltage for gradually increasing the first full-bridge circuit FB1 is stopped (FIG. 6B). The path (D3, Ci, D2) for applying a voltage for gradually reducing the current of 12 to the inductor 12 is configured to be a closed loop. Thereby, the boosting process (FIG. 6) can be performed.

  (3) The inductance setting of the electric path between the first full bridge circuit FB1 and the second full bridge circuit FB2 is configured by a leakage inductor of the transformer T. Thereby, the increase in the circuit scale accompanying inductance setting can be suppressed suitably.

(4) The first capacitor Ci is short-circuited between the positive terminal Tip1 and the negative terminal Tin1 of the first full-bridge circuit FB1, and the second capacitor is connected between the positive terminal Tip2 and the negative terminal Tin2 of the second full-bridge circuit FB2. Two capacitors Co were short-circuited. Thereby, the circuit configuration of the power transmission device can be simplified. In addition, since the inductance between the second full bridge circuit FB2 and the second capacitor Co can be minimized (ideally zero), the voltage Vo of the first capacitor Co and the voltage Vi of the second capacitor Ci can be reduced. Regardless of the value, in the state of FIG. 4B, the potential of the positive terminal Tip2 of the second full bridge circuit FB2 does not become lower than the potential of the negative terminal Tin2. For this reason, it is possible to avoid applying a reverse bias to the diodes Db and Dc (Da and Dd) with a simple setting during a period in which the forward current flows.
<Second Embodiment>
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 8 shows the system configuration of this embodiment. In FIG. 8, components corresponding to those shown in FIG. 1 are given the same reference numerals for convenience.

  The present embodiment is different in that a snubber circuit is provided between the second full bridge circuit FB2 and the second capacitor Co. The snubber circuit has the following configuration.

  That is, the positive terminal Tip2 of the second full bridge circuit FB2 and the second capacitor Co are connected via the smoothing coil 30. In addition, a series connection body of the snubber capacitor Cs and the first snubber diode Ds1 is connected between the positive terminal Tip2 and the negative terminal Tin2 of the second full bridge circuit FB2. A snubber capacitor Cs and a second snubber diode Ds2 are connected in parallel to the smoothing coil 30.

In the following, “charging process from the external commercial power source to the in-vehicle battery side” will be described, and then “power output processing from the in-vehicle battery side to the external commercial power source” will be described.
“Charging process from external commercial power source to in-vehicle battery”
In the present embodiment, as shown in FIG. 9, the phase shift process is performed by shifting the switching timing to the ON state and the switching timing to the OFF state between the switching elements Q1 (Q2) and Q4 (Q3). Do.

  Hereinafter, with reference to FIG. 10, a qualitative description will be given regarding the power transmission processing from the first coil w1 side to the second coil w2 side.

  FIG. 10A shows a state where both of the switching elements S1 and S4 are turned on. In this case, on the first coil w1 side, a current flows through a loop path including the first capacitor Ci, the switching element S1, the first coil w1, and the switching element S4. On the other hand, on the second coil w2 side, a current flows through a path including the second coil w2, the inductor 12, the diode Da, the smoothing coil 30, the second capacitor Co, and the diode Dd, and the snubber capacitor bypasses the smoothing coil 30. Current also flows through Cs and the second snubber diode Ds2. Here, the current flowing through the inductor 12 and the smoothing coil 30 gradually increases.

  At this time, the voltage across the smoothing coil 30 is clamped by the charging voltage of the snubber capacitor Cs. For this reason, compared with the case where the snubber capacitor | condenser Cs does not exist, the absolute value of the voltage applied to the smoothing coil 30 becomes small.

  FIG. 10B shows a state in which the switching element S1 is switched to the off state. In this state, due to the magnetic energy stored in the inductor 12, a current flows through a loop path including the first coil w1, the switching element S4, and the diode D2 on the first coil w1 side. On the other hand, on the second coil w2 side, a current flows through a path including the inductor 12, the diode Da, the smoothing coil 30, the second capacitor Co, and the diode Dd. At this time, the total voltage of the voltage VLs of the inductor 12 and the voltage VLo of the smoothing coil 30 becomes the voltage Vo of the second capacitor Co. Here, since the voltage VLo of the smoothing coil 30 becomes positive, a voltage that is reduced by the voltage VLo of the smoothing coil 30 with respect to the voltage Vo of the second capacitor Co is applied to the snubber capacitor Cs. In the present embodiment, the voltage Vs of the snubber capacitor Cs is set to be larger than “Ls · Vo / (Lo + Ls)” using the inductance Lo of the inductor 12 and the inductance Ls of the smoothing coil 30. In this case, the voltage VLo of the smoothing coil 30 is clamped to the differential pressure between the voltage Vo of the second capacitor Co and the voltage Vs of the snubber capacitor Cs, and the discharge of the snubber capacitor Cs is started.

  According to such setting, the voltage VLs of the inductor 12 is increased, so that the rate of decrease of the current flowing through the inductor 12 is increased. As a result, as shown in FIG. 10C, when the current flowing through the inductor 12 becomes zero, the current of the smoothing coil 30 becomes equal to the discharge current of the snubber capacitor Cs.

  After such a state is realized, the switching elements S2 and S3 are switched to the on state in the manner shown in FIG.

  Thus, in the present embodiment, the output current of the second full bridge circuit FB2 can be gradually reduced to zero prior to the on operation of the switching elements S1, S4 (S2, S3). A surge voltage associated with the recovery current of Dd can be suitably avoided.

In FIG. 10C, a state in which the switching element S2 is turned on is shown. However, even if a current flows through the first coil w1 when the switching element S2 is turned on, this switching is performed. Is zero volt switching. This is because the switching state is switched in a state where a current flows through the diode D2. This phase shift process is executed by utilizing the current flowing through the first coil w1 during the discharge period of the magnetic energy stored in the inductor 12.
“Processing of power output from in-vehicle battery to external commercial power supply”
In the present embodiment, as shown in FIG. 11, the operation signals msa, msd and the operation signals msb, msc are the same signals, and the operation signals msa, msd and the operation signals msb, msc are used as an on operation command. The phase of the period is set to be shifted by π. Thereby, the second full bridge circuit FB2 can be used as a DC / AC converting means for converting a DC voltage (voltage of the second capacitor Co) into an AC voltage.

  Further, the operation signal ms4 is switched to the on operation command in synchronization with the switching of the operation signals msa and msd to the on operation command, and the operation signal ms2 is turned on in synchronization with the switching of the operation signals msb and msc to the on operation command. Switch to command. This is a process for storing electrical energy in the inductor 12.

  Hereinafter, with reference to FIG. 12, a qualitative explanation will be given regarding the power transmission processing from the second coil w2 side to the first coil w1 side.

  FIG. 12A shows a state in which the switching elements Sb and Sc of the second full bridge circuit FB2 and the switching element S2 of the first full bridge circuit FB1 are switched to the on state. Since the transition to this state is performed before the magnetic energy of the inductor 12 becomes zero, the current that has previously flowed through the inductor 12 flows immediately after the transition to this state. As a result, on the first coil w1 side, a current flows through a loop path including the first coil w1, the diode D1, the first capacitor Ci, and the diode D4. On the other hand, on the second coil w2 side, a current flows through a loop path including the second coil w2, the diode Dc, the snubber capacitor Cs, the second snubber diode Ds2, the second capacitor Co, the diode Db, and the inductor 12. At this time, the current flowing through the smoothing coil 30 gradually decreases according to the ratio between the charging voltage of the snubber capacitor Cs and the inductance Lo of the smoothing coil 30. The current flowing through the inductor 12 gradually decreases in proportion to the value obtained by subtracting the sum of the voltage of the snubber capacitor Cs and the voltage of the second capacitor Co from the voltage of the second coil w2.

  FIG. 12B shows a state in which the current starts flowing in the reverse direction after the current flowing through the inductor 12 becomes zero. In this state, a current flows through a loop path including the first coil w1, the switching element S2, and the diode D4 on the first coil w1 side. That is, there is a detour path that bypasses the first capacitor Ci by an electrical path that is connected only to the side of the first full-bridge circuit FB1 that is connected to the negative terminal Tin1 among the positive terminal Tip1 and the negative terminal Tin1. It is formed.

  In this case, the voltage applied to the first coil w1 and the second coil w2 can be regarded as zero. For this reason, the current flowing through the loop path including the second capacitor Co, the smoothing coil 30, the switching element Sc, the second coil w2, the inductor 12, and the switching element Sb gradually increases. Here, in the state shown in FIG. 12B, the snubber capacitor Cs is charged. This occurs because a part of the current of the smoothing coil 30 flows into the snubber capacitor Cs during a period during which the current flowing through the inductor 12 increases to the current flowing through the smoothing coil 30.

  FIG. 12C shows a state where the charging current of the snubber capacitor Cs becomes zero. Thereafter, the snubber capacitor Cs starts discharging because the voltage Vs of the snubber capacitor Cs is larger than a value obtained by subtracting “Lo · Vo / (Lo + Ls)” from the voltage Vo of the second capacitor Co. Accordingly, the absolute value of the voltage VLo of the smoothing coil 30 becomes smaller than that obtained by dividing the voltage Vo of the second capacitor Co into “Lo: Ls”.

  FIG. 13A shows a state in which the switching element S2 is turned off. In this case, on the first coil w1 side, a current flows through a loop path including the first coil w1, the diode D1, the first capacitor Ci, and the diode D4. This is a phenomenon that occurs when the magnetic energy stored in the inductor 12 is released. As a result, the voltage Vw2 of the second coil w2 becomes “−n · Vi”, which is higher than the voltage Vo of the second capacitor Co. Therefore, the current flowing through the inductor 12 gradually decreases.

  However, since the discharge current flows through the snubber capacitor Cs immediately before the switching element S2 is turned off, the current flowing through the inductor 12 does not match the current flowing through the smoothing coil 30 at the time when the switching element S2 is turned off. For this reason, the snubber capacitor Cs continues to discharge until the current flowing through the inductor 12 decreases and its absolute value matches the absolute value of the current flowing through the smoothing coil 30. In this case, the voltage VLo applied to the smoothing coil 30 gradually increases the current flowing through the smoothing coil 30.

  Thereafter, when the current flowing through the inductor 12 and the current flowing through the smoothing coil 30 coincide with each other, the discharge of the snubber capacitor Cs ends as shown in FIG.

  FIG. 13C shows a state in which the switching elements Sb and Sc are turned off and the switching elements Sa, Sd and S4 are turned on, and corresponds to the state shown in FIG.

  FIG. 14 shows changes in various electrical state quantities in the above processing. In the figure, “voltage between Sc and Sd” is the voltage across the serially connected body of the switching elements Sc and Sd.

  Hereinafter, several effects other than the effects (1) and (3) of the first embodiment will be described as the effects of the above embodiment.

  (6) By setting the capacitance of the snubber capacitor Cs and the like, the gradual decrease rate of the current of the inductor 12 is sufficiently increased than that of the smoothing coil 30 (FIG. 10). As a result, while the current flowing through the smoothing coil 30 is set to the continuous mode, the output current of the second full-bridge circuit FB2 can be made zero prior to the reversal of the polarity of the voltage applied to the second coil w2, and thus the recovery. A surge caused by an electric current can be suitably avoided.

(7) Phase shift processing was performed by using the inductor 12. This eliminates the need for a separate inductor when performing the phase shift process.
<Third Embodiment>
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 15 shows the system configuration of this embodiment. In FIG. 15, the same reference numerals are assigned for convenience to the members corresponding to the members shown in FIG.

  As illustrated, in the present embodiment, a first half bridge circuit HB1 and a second half bridge circuit HB2 are provided instead of the first full bridge circuit FB1 and the second full bridge circuit FB2. Each of the first half bridge circuit HB1 and the second half bridge circuit HB2 is a parallel connection body of a series connection body of a pair of switching elements and a series connection body of a pair of capacitors.

  That is, the first half bridge circuit HB1 is a parallel connection body of a series connection body of the switching elements S1 and S2 and a series connection body of the capacitors C1 and C2. The second half bridge circuit HB2 is a parallel connection body of a series connection body of the switching elements Sa and Sb and a series connection body of the capacitors Ca and Cb.

  FIG. 16A shows a switching control method in “charging process from an external commercial power source to the in-vehicle battery”. As shown in the figure, in this case, the switching elements S1 and S2 are alternately turned on while being shifted in phase by π.

  FIG. 16B shows a switching control method in “output processing of electric power from the in-vehicle battery side to the external commercial power source”. As illustrated, in this case, the switching elements Sa and Sb are alternately turned on, and the switching element S2 (S1) is turned on in synchronization with the switching element Sa (Sb) being turned on.

Here, when the switching elements Sa and S2 are turned on, a current flows through a loop path including the first coil w1, the switching element S2, and the capacitor C2 on the first coil w1 side. This electrical path is a bypass path that bypasses the first capacitor Ci. Magnetic current can be stored in the inductor 12 by the current flowing through the bypass path.
<Fourth Embodiment>
Hereinafter, the fourth embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 17 shows the system configuration of this embodiment. Note that, in FIG. 17, the same reference numerals are attached for convenience to those corresponding to the members shown in FIG. 1.

  As illustrated, in the present embodiment, instead of the first full bridge circuit FB1 and the second full bridge circuit FB2, a first rectification bridge circuit RB1 and a second rectification bridge circuit RB2 are provided.

  The first rectifier bridge circuit RB1 includes a parallel connection of a series connection of a high potential side switching element S1 and a low potential side diode D2, and a series connection of a high potential side diode D3 and a low potential side switching element S4. Is the body. The second rectifier bridge circuit RB2 includes a parallel connection of a series connection body of the high potential side switching element Sc and the low potential side diode Dd and a series connection body of the high potential side diode Da and the low potential side switching element Sb. Is the body.

  FIG. 18A shows a switching control method in the “charging process from an external commercial power source to the in-vehicle battery”. As illustrated, in this case, a period in which both of the switching elements S1 and S4 are turned on and a period in which the switching elements S4 are turned off are alternately generated.

FIG. 18B shows a switching control method in “output processing of electric power from the vehicle battery side to the external commercial power source”. As shown in the figure, in this case, the period in which both of the switching elements Sb, Sc are turned on and the period in which the switching elements Sb are turned off are alternately realized and the switching elements Sb, Sc are turned on. The switching element S4 is turned on in synchronization. Here, in the present embodiment, in order to store magnetic energy in the inductor 12 during the period in which the switching element S4 is turned on, in this embodiment, the polarity of the voltage induced in the first coil w1 during this period is the first coil w1 and the switching. In a loop path including the element S4 and the diode D2, a current can flow in the forward direction of the diode D2.
<Fifth Embodiment>
Hereinafter, the fifth embodiment will be described with reference to the drawings with a focus on differences from the second embodiment.

  FIG. 19 shows a system configuration of the present embodiment. Note that, in FIG. 19, the same reference numerals are given for the sake of convenience for those corresponding to the members shown in FIG.

As illustrated, in the present embodiment, the switching element Ss is connected in parallel to the first snubber diode Ds1. Thereby, when the switching element Ss is turned on, the snubber capacitor Cs can be a smoothing capacitor. In this case, since the snubber capacitor Cs and the smoothing coil 30 constitute an LC filter, the voltage that can be applied to the second coil w2 is increased in the “power output process from the in-vehicle battery side to the external commercial power source”. be able to.
<Other embodiments>
Each of the above embodiments may be modified as follows.

“High-voltage side bridge circuit (FB1, HB1, B1)”
a) First full-bridge circuit FB1
In the first embodiment (FIG. 1) and the second embodiment (FIG. 8), the switching elements 1 and 3 have a function that enables only power transmission processing from the capacitor Co side to the capacitor Ci side. Is not required. In other words, the opening / closing function (S1, S3) is not essential for the positive-side flow regulating element that connects the terminal of the first coil w1 and the positive electrode of the capacitor Ci, and only the rectifying function (D1, D3) may be provided. .

  In the first embodiment (FIG. 1) and the second embodiment (FIG. 8), the diodes D2 and D4 are not essential. In other words, the rectifying function (D2, D4) is not indispensable for the negative-side flow restricting element that connects the terminal of the first coil w1 and the negative electrode of the capacitor Ci, and only the open / close function (S2, S4) may be provided. .

b) First half-bridge circuit HB1
In the third embodiment (FIGS. 15 and 16), the switching elements S1 and S2 are switched by switching the operation signal ms1 from the on operation command to the off operation command and switching the operation signal ms2 from the off operation command to the on operation command. When used as a synchronous rectifier, the diodes D1 and D2 are not essential.

c) First rectification bridge circuit RB1
In the fourth embodiment (FIG. 17), a switching element may be connected in parallel to the diodes D2 and D3. That is, a negative-side flow restriction element connected to one terminal of the first coil w1 and a positive-side flow restriction element connected to the other terminal of the first coil w1 are configured to include a switching element and a diode. May be.

"About the low voltage side bridge circuit (FB2, HB2, B2)"
For example, in the second embodiment (FIG. 8), the second half bridge circuit HB2 may be used instead of the second full bridge circuit FB2 as illustrated in the third embodiment (FIG. 15). For example, the second rectifying bridge circuit RB2 exemplified in the fourth embodiment (FIG. 17) may be used.

“Inductance setting”
In each of the above embodiments, the inductor 12 is configured as a leakage inductor of the transformer T. However, the present invention is not limited to this, and an inductance element may be used. In this case, the inductance element may be disposed at least one of the second coil w2 and the second full bridge circuit FB2 and the first full bridge circuit FB1 and the first coil w1.

“Setting the capacitance of snubber capacitor Cs”
As illustrated in FIG. 10, the setting is not limited to the setting in which the discharge current of the snubber capacitor Cs is supplied to the smoothing coil 30 even after the current flowing through the inductor 12 becomes zero. Even if it is not set as such, surge can be absorbed by the snubber circuit.

"About snubber circuit"
The first snubber distribution restriction element is not limited to the first snubber diode Ds1, but may be a switching element that is controlled to be in an on state over a period in which a forward current flows through the first snubber diode Ds1.

  The second snubber distribution restriction element is not limited to the second snubber diode Ds2, but may be a switching element that is controlled to be in an on state over a period in which a forward current flows through the second snubber diode Ds2.

  In the second embodiment (FIG. 8), an inductor may be provided between the first snubber diode Ds1 and the second snubber diode Ds2.

“Charging process from external commercial power source to in-vehicle battery”
In the first embodiment (FIG. 4), the switching elements S2, S3 (S1, S4) may be turned on before the current flowing through the inductor 12 becomes zero. However, in order to maintain symmetry between the ON periods of the switching elements S2 and S3 and the ON periods of the switching elements S1 and S4, the timing before the center of the ON period of the switching elements S2, S3 (S1, S4) It is desirable that the current flowing through the inductor 12 gradually decreases to zero (passes through zero).

  In the first embodiment, phase shift processing may be performed. This can be realized by using the inductor 12.

  In the second embodiment, hard switching processing may be performed without performing phase shift processing.

“Connection between the second full-bridge circuit FB2 and the second capacitor Co”
In the first embodiment (FIG. 1), a smoothing coil may be provided between the positive terminal Tip2 of the second full bridge circuit FB2 and the second capacitor Co. Even in this case, depending on the setting of the inductance of the smoothing coil, the current flowing through the inductor 12 and the smoothing coil can be made the same amount and the gradual reduction speed can be made the same, so that the recovery current flows through the diodes Da to Dd. This can be preferably avoided, and as a result, the surge voltage can be suitably reduced. Here, the setting of the inductance Lo only needs to satisfy “Vo−VLo ≧ 0”. That is, it is only necessary to satisfy the condition of satisfying “Lo / Ls ≦ nVo / Vin” in the range of values that the voltage Vo of the first capacitor Ci and the voltage Vo of the second capacitor Co can take. However, in a situation where surge is not a problem, it is not essential that the above condition is satisfied.

"Application of converter CNV"
The power conversion circuit for charging the on-vehicle high voltage battery with the electric power of the commercial power source outside the vehicle is not limited to the configuration.

  Ci ... first capacitor, Co ... second capacitor, FB1 ... first full bridge circuit (one embodiment of high voltage side bridge circuit), FB2 ... second full bridge circuit (one embodiment of low voltage side bridge circuit).

Claims (7)

A first coil (w1);
A first bridge circuit (FB1) connected to the first coil;
A second coil (w2) magnetically coupled to the first coil;
A second bridge circuit (FB2) connected to the second coil;
With
The electrical path between the first bridge circuit and the second bridge circuit has an inductance setting that can increase or decrease the stored energy in accordance with the increase or decrease of the current flowing through the first coil and the second coil. ,
The first bridge circuit connects one terminal and the other terminal of the first coil to the positive terminal (Tip1) and the negative terminal (Tin1) of the first bridge circuit by the legs. Is what
The second bridge circuit connects one terminal and the other terminal of the second coil to the positive terminal (Tip2) and the negative terminal (Tin2) of the second bridge circuit according to the leg. Is what
Of the first bridge circuit and the second bridge circuit, from the low voltage side bridge circuit (FB2) in which the voltage applied to the coil connected to the first bridge circuit and the second bridge circuit is the smaller value divided by the number of turns of the coil. To the higher voltage side bridge circuit (FB1) which is larger, the low voltage side coil and the low voltage side coil which are coils connected to the low voltage side bridge circuit among the first coil and the second coil, A step-up processing means (20) for operating the first bridge circuit and the second bridge circuit to transmit power via a high-voltage side coil that is a magnetically coupled coil;
The boosting processing means includes:
Close the detour path to which both ends of the high voltage side coil are connected only through the path connected to either the positive side terminal or the negative side terminal of the high voltage side bridge circuit. And an accumulation process for accumulating energy in the electric path by gradually increasing a current in the electric path between the first bridge circuit and the second bridge circuit;
Boosting processing for outputting the energy accumulated by the accumulation processing to the outside of the high-voltage side bridge circuit via the positive-side terminal and the negative-side terminal of the high-voltage side bridge circuit by opening the bypass path When,
The power transmission apparatus characterized by performing. The high-voltage side bridge circuit includes a positive-side flow restricting element (S1) that connects one terminal of the high-voltage side coil to the positive-side terminal, and a negative-side flow that connects the one terminal to the negative-side terminal. A regulating element (S2), a positive-side flow regulating element (S3) that connects the other terminal of the high-voltage side coil to the positive-side terminal, and a negative-side flow regulation that connects the other terminal to the negative-side terminal An element (S4),
The positive-side flow regulating element allows an open / close function to open and close a current flow path, and allows and reverses a current in a direction from the high-voltage side coil side to the positive-side terminal side in the current flow path. Having at least one function of a rectifying function to block current in the direction,
The negative electrode side flow regulating element has an opening / closing function for opening / closing a current flow path,
The bypass path is connected to a path generated by closing the negative-side flow restricting element connected to one terminal of the high-voltage side coil and to the other terminal of the high-voltage side coil. The power transmission device according to claim 1, further comprising: a path generated by closing the negative electrode side flow restriction element. The high voltage side bridge circuit includes a capacitor (C1, C2) for connecting one terminal of the high voltage side coil to each of the positive side terminal and the negative side terminal, and the other terminal of the high voltage side coil. Switching elements (S1, S2) connected to each of the positive terminal and the negative terminal,
The bypass path includes a path generated by turning on a switching element that connects the other terminal of the high-voltage side coil to the negative-side terminal, and the other terminal of the high-voltage side coil as the positive-side. The power transmission device according to claim 1, further comprising: a path generated by turning on a switching element connected to the terminal. The high-voltage side bridge circuit includes a positive-side flow restricting element (S1) that connects one terminal of the high-voltage side coil to the positive-side terminal, and a negative-side flow that connects the one terminal to the negative-side terminal. A regulating element (D2), a positive-side flow regulating element (D3) that connects the other terminal of the high-voltage side coil to the positive-side terminal, and a negative-side flow regulation that connects the other terminal to the negative-side terminal An element (S4),
The positive side flow restriction element connected to the one terminal of the high voltage side coil and the negative side flow restriction element connected to the other terminal of the high voltage side coil open and close a current flow path. Has an opening and closing function
The positive-side flow restricting element connected to the other terminal of the high-voltage side coil allows current in the direction from the other terminal side to the positive-side terminal side and blocks current in the reverse direction. Has a rectifying function,
The negative-side flow restricting element connected to the one terminal of the high-voltage side coil allows current in a direction from the negative-side terminal side to the one-terminal side and blocks current in the reverse direction. Has a rectifying function,
The detour path includes a path generated by closing the negative-side flow restriction element connected to the other terminal,
The step-up processing means closes the negative-side flow restricting element connected to the other terminal, and induces a voltage at which the one terminal side of the high-voltage side coil is positive. The power transmission device according to claim 1, wherein the bridge circuit is operated. Comprising a smoothing capacitor connected between the positive terminal and the negative terminal of the low voltage side bridge circuit;
The smoothing capacitor is connected to the low voltage via a pair of electrical paths, an electrical path connected to the positive terminal (Tip2) of the low voltage side bridge circuit and an electrical path connected to the negative terminal (Tin2). Connected to the side bridge circuit,
The power transmission device according to any one of claims 1 to 4, wherein a branch path is not provided in the pair of electrical paths. A series connection body of a smoothing coil (30) and a smoothing capacitor (Co) is connected between the positive terminal (Tip2) and the negative terminal (Tin2) of the low voltage side bridge circuit,
A snubber capacitor (Cs) and a first snubber distribution restriction element (Ds1) are connected in parallel to the series connection body,
The snubber capacitor and the second snubber flow restricting element (Ds2) are connected in parallel to the smoothing capacitor,
The first snubber flow restricting element (Ds1) has a function of allowing a current flow from the negative terminal side to the snubber capacitor side and blocking a reverse flow,
The second snubber flow regulating element (Ds2) has a function of allowing a current flow from the positive terminal side to the smoothing capacitor side and blocking a reverse current flow. The power transmission device according to any one of claims 1 to 4.   The power transmission device according to claim 1, wherein the inductance setting is configured by a leakage inductance related to magnetic coupling between the first coil and the second coil.

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