JP2017060285A - Transformer reactor integrated type magnetic element and power conversion circuit system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transformer reactor integrated type magnetic element and power conversion circuit system, capable of reducing a dead space between magnetic elements and a heat sink size as well as number of components and wiring length.SOLUTION: Primary transformer coils 12a, 12b are arranged at both ends of an E-type core 10 with legs in the center and at both ends and secondary transformer coils 14a, 14b are arranged. By supplying an in-phase current to the primary transformer coils 12a, 12b, a magnetic element is operated with a reactor and by supplying a reverse-phase current to the primary transformer coils 12a, 12b, the magnetic element is operated with a transformer, thereby reducing the number of reactor coils.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a transformer-integrated magnetic element and a power conversion circuit system, and more particularly to a power conversion circuit system including a plurality of input / output ports.

  With the development and popularization of electric-rich vehicles such as hybrid vehicles, electric vehicles, and fuel cell vehicles, on-board power supply circuits are becoming more complex and larger. For example, in a hybrid vehicle, a traveling battery, a system battery, an external power supply circuit for plug-in, a DC / DC converter for supplying direct current power of the traveling battery to the traveling motor, and direct current power of the traveling battery to alternating current DC / AC converter for converting to electric power, DC / DC converter for supplying DC power of the traveling battery to the electric power steering (EPS), DC / DC for supplying DC power of the traveling battery to the auxiliary machine There are DC converters, etc., and the configuration is complicated.

  Therefore, development of a multi-port power supply having a plurality of inputs / outputs in one circuit is underway. It has been proposed to reduce the size of a power supply circuit by sharing wirings, semiconductor elements, and the like with a multiport power supply. At this time, it is effective to wind the transformer coil and the reactor coil around the core so as not to interfere with each other.

  Patent Document 1 describes a configuration in which a transformer coil and a reactor coil are wound around a core having three legs so as not to interfere with each other, and the dead space between magnetic elements and the heat sink size are reduced. it can.

  FIG. 11 shows a cross-sectional view of the magnetic element described in this document. Transformer coils 12a, 12b, 14a, and 14b are disposed on both leg portions of the core 10 having three legs, and two reactor coils 16a and 16b are disposed on the center leg portion. The transformer coils 12a and 12b are primary (low voltage side) transformer coils, and the transformer coils 14a and 14b are secondary (high voltage side) transformer coils.

  12A and 12B show a magnetic flux change and a circuit configuration when the magnetic element of FIG. 11 is operated as a transformer. When current is applied so that the transformer coils 12a and 12b are in opposite phases, the direction of magnetic flux generation by the transformer coils 12a and 12b is reversed at both ends, so that the magnetic flux changes at the center leg are canceled out. Therefore, magnetic flux does not pass through the reactor coils 16a and 16b arranged at the center leg, and no electromotive force is generated.

  On the other hand, FIG. 13A and FIG. 13B show magnetic flux changes and circuit configurations when the magnetic element of FIG. 11 is operated as a reactor. When current is passed so that the transformer coils 12a and 12b are in phase with each other, the magnetic flux generated from the reactor coils 16a and 16b arranged at the center leg is linked to the transformer coils 12a and 12b. However, since the upper and lower transformer coils 12a and 12b through the center tap are opposite to each other, the electromotive force of the entire coil becomes zero and the transformer does not operate. Based on the above principle, the transformer coil and the reactor coil operate without interfering with each other.

JP 2012-134266 A

  In the conventional technology, the dead space between the magnetic elements and the heat sink size can be reduced by arranging the transformer coil and the reactor coil in the core having three legs. However, the number of parts and the winding length can be further reduced. Shortening is required.

  An object of the present invention is to provide a transformer-integrated magnetic element and a power conversion circuit system capable of further reducing the number of components and the winding length in addition to reducing the dead space between the magnetic elements and the heat sink size. is there.

  The transformer-integrated magnetic element of the present invention includes a central leg portion, a core having leg portions at both ends, a first primary transformer coil and a first coil wound around either of the leg portions at both ends. And a second primary transformer coil and a second secondary transformer coil wound around either one of the leg portions at both ends, and the first primary side The transformer coil and the second primary transformer coil are connected in series, the first secondary transformer coil and the second secondary transformer coil are connected in series, and are connected to the central leg of the core. The reactor coil operates without a reactor coil being wound, and a common-mode current is supplied to the first primary transformer coil and the second primary transformer coil, and the first primary transformer coil And the second primary side Reverse phase currents lance coil is characterized in that the transformer operates by being supplied.

  The power conversion circuit system of the present invention is a primary side conversion circuit, comprising a left arm and a right arm between a primary side positive bus and a primary side negative bus, wherein the left arm and the right arm are Each of the two switching transistors is connected in series, and a first primary transformer coil and a second switching coil are connected between a connection point of the two switching transistors of the left arm and a connection point of the two switching transistors of the right arm. A primary side converter circuit in which a primary transformer coil is connected in series and a secondary side converter circuit, comprising a left arm and a right arm between a secondary side positive bus and a secondary side negative bus, Each of the arm and the right arm is composed of two switching transistors connected in series, and the connection point between the two switching transistors of the left arm and 2 of the right arm. A secondary conversion circuit in which a first secondary transformer coil and a second secondary transformer coil are connected in series between connection points of the switching transistors, the primary conversion circuit, and the secondary conversion A control circuit that controls switching of the switching transistor of the circuit, wherein the first primary transformer coil and the first secondary transformer coil include a central leg and leg parts at both ends. The first secondary transformer coil and the second secondary transformer coil are wound around either one of the leg portions of the core. A reactor coil is not wound around the central leg portion of the core, and a reactor is supplied with an in-phase current supplied to the first primary transformer coil and the second primary transformer coil. Was created, the first primary transformer coil and reverse current to the second primary transformer coil is characterized in that the transformer operates by being supplied.

  In the present invention, in order to use the leakage inductance between the first primary coil and the second primary coil wound around the leg portions at both ends of the core as a reactor, the reactor coil is separately wound. There is no need, and the reactor coil can be reduced. In the present invention, the transformer operation and the reactor operation are realized only by the transformer coil without having the reactor coil.

  According to the present invention, in addition to the dead space between magnetic elements and the reduction of the heat sink size, it is possible to further reduce the number of parts and the winding length. Further, with the shortening of the winding length, the AC resistance loss can be reduced.

It is a circuit block diagram of an embodiment. It is a cross-sectional view of the magnetic element of the embodiment. It is explanatory drawing which shows the flow of the electric current at the time of the trans | transformer operation | movement of the magnetic element of embodiment. It is explanatory drawing which shows the flow of the electric current at the time of the reactor operation | movement of the magnetic element of embodiment. It is explanatory drawing which shows the magnetic flux at the time of the trans | transformer operation | movement of the magnetic element of embodiment. It is a circuit diagram at the time of the transformer operation | movement of the magnetic element of embodiment. It is explanatory drawing which shows the magnetic flux at the time of the reactor operation | movement of the magnetic element of embodiment. It is a circuit diagram at the time of the reactor operation | movement of the magnetic element of embodiment. It is a block diagram of the magnetic element of embodiment. It is a simulation circuit diagram of an embodiment. It is explanatory drawing (common-mode current) of the magnetoresistive model in the simulation of embodiment. It is explanatory drawing (common-mode current) of the magnetoresistive model in the simulation of embodiment. It is explanatory drawing (reverse phase current) of the magnetoresistive model in the simulation of embodiment. It is explanatory drawing (reverse phase current) of the magnetoresistive model in the simulation of embodiment. It is a graph which shows the voltage change in the simulation of embodiment. It is a graph which shows the electric current change in the simulation of embodiment. It is a graph which shows the magnetic flux change in the simulation of embodiment. It is a graph which shows the magnetic flux change at the time of the in-phase current in the simulation of embodiment, and the reverse-phase current. It is a cross-sectional view of a conventional magnetic element. It is explanatory drawing which shows the magnetic flux at the time of the trans | transformer operation | movement of the magnetic element of a prior art. It is a circuit diagram at the time of the transformer operation | movement of the magnetic element of a prior art. It is explanatory drawing which shows the magnetic flux at the time of the reactor operation | movement of the magnetic element of a prior art. It is a circuit diagram at the time of the reactor operation | movement of the magnetic element of a prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a circuit configuration diagram of a power conversion circuit system in the present embodiment. The power conversion circuit system includes a control circuit 100 and a power conversion circuit 120. The power conversion circuit 120 is a three-port multiport circuit capable of bidirectional power transmission between three DC power supplies using a magnetically coupled reactor.

  The multi-port circuit includes a port A and a port C in the primary side conversion circuit, and a port B and a port D in the secondary side conversion circuit.

  Between the positive bus of the primary side conversion circuit and the negative bus of the primary conversion circuit, the left arm consisting of switching transistors S1 and S2 connected in series with each other, and the switching transistors S3 and S4 connected in series with each other The left arm and the right arm are connected in parallel to each other to form a full bridge circuit. Port A is disposed between the positive and negative buses of the primary conversion circuit. The input / output voltage of port A is VA. Port C is arranged between the negative electrode bus of the primary side conversion circuit and the transformer. The input / output voltage of port C is set to VC.

  A magnetically coupled reactor (reactor coil) connected in series is connected between a connection point of the switching transistors S1 and S2 constituting the left arm and a connection point of the switching transistors S3 and S4 constituting the right arm. The primary windings (transformer coils) 12a and 12b of the transformer (transformer coil) are connected. That is, the magnetic coupling reactor and the primary transformer coils 12a and 12b are connected to the midpoint of the two bidirectional chopper circuits.

  On the other hand, between the positive electrode bus and the negative electrode bus of the secondary side conversion circuit, there is a left arm composed of switching transistors S5 and S6 connected in series with each other and a right arm composed of switching transistors S7 and S8 connected in series with each other. The left arm and the right arm are connected in parallel to each other to form a full bridge circuit. Port B is disposed between the positive and negative buses of the secondary conversion circuit. The input / output voltage of port B is VB.

  The secondary windings (transformer coils) 14a and 14b of the transformer are connected between the connection point of the switching transistors S5 and S6 constituting the left arm and the connection point of the switching transistors S7 and S8 constituting the right arm. .

  The control circuit 100 sets various parameters for controlling the power conversion circuit 120 and performs switching control of the switching transistors S1 to S8 of the primary side conversion circuit and the secondary side conversion circuit. The control circuit 100 switches between a mode for performing power conversion between the two ports of the primary side conversion circuit and a mode for performing isolated power transmission between the primary side and the secondary side based on a mode signal from the outside. In terms of ports, the circuit is operated as a bidirectional isolated converter between port A and port B, and the circuit is operated as a bidirectional non-isolated converter between port A and port C. At this time, the magnetically coupled reactor uses a leakage inductance component to weaken the magnetic flux in the bidirectional insulated converter operation, and a sum component of the excitation inductance component and the leakage inductance component to strengthen the magnetic flux in the bidirectional non-insulated converter operation. Power transmission is performed using

The insulated power transmission between the primary side conversion circuit and the secondary side conversion circuit is controlled by the phase difference φ of the switching cycle of the switching transistors S1 to S8 of the primary side conversion circuit and the secondary side conversion circuit. When power is transmitted from the primary side conversion circuit to the secondary side conversion circuit, the phase difference φ is determined so that the primary side is in advance with respect to the secondary side. In contrast, when power is transmitted from the secondary side conversion circuit to the primary side conversion circuit, the phase difference φ is determined so that the primary side is delayed from the secondary side. For example, when power is transmitted from the secondary side conversion circuit to the primary side conversion circuit, the switching transistors S1 and S4 are turned on and S2 and S3 are turned off in the primary side conversion circuit. In the secondary conversion circuit, the switching transistors S5 and S8 are turned on, and S6 and S7 are turned off. In the secondary side conversion circuit,
S5 → Transformer secondary winding → S8
And current flows. In the primary side conversion circuit,
S4 → transformer primary winding → S1
And current flows.

  In the next period, the switching transistors S1, S4, and S8 are turned on, and the others are turned off. Compared to the previous period, the switching transistor S5 changes from on to off, but when the switching transistor S5 of the secondary conversion circuit is turned off, current continues to flow through the diode connected in parallel to the switching transistor S6. The voltage across the secondary side drops to zero. Therefore, it is the on / off state of the switching transistor S5 that determines the voltage across the secondary side.

  In the next period, the switching transistors S1, S4, S6, and S8 are turned on, and the others are turned off.

  In the next period, the switching transistors S4, S6, and S8 are turned on and the others are turned off. When the switching transistor S1 of the primary side conversion circuit transitions from on to off, current continues to flow through a diode connected in parallel to the switching transistor S1, and the voltage across the primary side is zero unless the switching transistor S2 is turned on. do not become. Therefore, it is the on / off state of the switching transistor S2 that determines the voltage across the primary side.

  A dead time of about several hundred nanoseconds to several microseconds may be provided so that the upper and lower switching transistors are not short-circuited. That is, a period in which both the switching transistors S1 and S2, S3 and S4, S5 and S6, and S7 and S8 are off may be provided.

  When the multi-port circuit of FIG. 1 is mounted on a hybrid vehicle, for example, a 48V auxiliary machine can be connected to port A, a 14V auxiliary machine can be connected to port C, and a main battery or the like can be connected to port B.

  In the multi-port circuit as described above, a transformer operation by a transformer coil and a reactor operation by a reactor coil are required, and in a conventional magnetic element, as described above, a transformer coil is attached to the legs of both ends of a core having three legs. The reactor coil was placed on the center leg.

  By the way, in the conventional magnetic element, when executing the reactor operation, the self-inductance of the magnetically coupled reactor is used as the reactor, but leakage inductance is generated between the upper and lower transformer coils via the center tap. This leakage inductance can be used as a reactor instead of the self-inductance of the magnetically coupled reactor.

  In this embodiment, under such an idea, the reactor coil is reduced, and the transformer coil is utilized as a magnetic element that realizes not only the transformer operation but also the reactor operation.

  FIG. 2 shows a cross-sectional view of the magnetic element in the present embodiment. Transformer coils 12a, 12b, 14a, 14b are arranged on the leg portions at both ends of the core 10 having three legs. The transformer coil 12a is a first primary transformer coil, the transformer coil 12b is a second primary transformer coil, the transformer coil 14a is a first secondary transformer coil, and the transformer coil 14b is a second secondary coil. This is a side transformer coil.

  When comparing FIG. 2 and FIG. 11, reactor coils 16a and 16b are arranged at the center leg in the magnetic element of FIG. 11, but no reactor coil is arranged at the center leg in the magnetic element of FIG. . That is, in the magnetic element of FIG. 2, the transformer coils 12a, 12b, 14a, and 14b at both ends function not only as a transformer coil but also as a reactor coil.

  FIG. 3A shows a current flow during operation of the transformer when the magnetic element shown in FIG. 2 is viewed from above. The transformer coils 12a and 12b are respectively arranged on the leg portions at both ends of the core 10 having the three leg portions, and currents flow in opposite phases in the transformer operation. That is, as shown in FIG. 3A, the current flows through the transformer coil 12a on the left leg among the leg sections at both ends in a counterclockwise direction when viewed from above, while the transformer coil 12b on the right leg section has a current. Current flows clockwise as viewed from above.

  FIG. 3B shows a current flow during the reactor operation when the magnetic element shown in FIG. 2 is viewed from above. The transformer coils 12a and 12b are respectively disposed on the leg portions at both ends of the core 10 having the three leg portions, and current flows so as to be in phase with each other in the reactor operation. That is, as shown in FIG. 3B, a current flows in the counter-clockwise direction when viewed from above in the transformer coil 12a on the left leg of the legs at both ends, and the transformer coil 12b on the right leg is also viewed from above. Current flows counterclockwise.

  4A and 4B show magnetic flux and circuit diagrams in transformer operation. Since the directions of the magnetic fluxes by the transformer coils 12a and 12b respectively disposed on the left and right legs are opposite to each other, the center legs cancel each other and do not operate as a reactor. This is the same magnetic flux change as an O-shaped transformer without a central leg.

  5A and 5B show magnetic flux and circuit diagrams in the reactor operation. Since the direction of the magnetic flux by the transformer coils 12a and 12b disposed on the left and right legs is the same, the magnetic flux does not cancel each other at the center leg, but the generated electromotive force is generated by the transformer coil 12a via the center tap. , 12b, the electromotive force of the entire coil becomes zero and the coil does not operate as a transformer. In addition, the reactor has a characteristic that it is difficult to saturate because the magnetic flux changes in a path with a large magnetic resistance through the gap.

  FIG. 6 shows a configuration diagram of the magnetic element of the present embodiment. The primary transformer coil 12a is wound around one of the leg portions at both ends of the core 10 having three legs, and the primary transformer coil 12b is wound around the other leg portion. Specifically, as shown in FIG. 1, a transformer coil 12a is connected between the U terminal of the primary left arm and the port C, and a transformer is connected between the V terminal of the primary right arm and the port C. The coil 12b is connected. The transformer coils 12a and 12b are connected in series via a center tap, and the port C is connected to the center tap.

  On the other hand, the secondary transformer coil 14a is wound around one of the leg portions at both ends of the core 10 having three legs, and the secondary transformer coil 14b is wound around the other leg portion.

  As described above, in this embodiment, a transformer coil is wound around both ends of a core having three legs (or an E-type core) to operate as a reactor with respect to a change in common-mode current, and a change in reverse-phase current is caused. On the other hand, the reactor coil can be deleted by operating as a transformer. The winding length (wiring length) is shortened by the absence of the reactor coil compared to the conventional magnetic element, and the core window for wiring is also reduced.

  Next, an operation simulation result by the computer of the multiport circuit in the present embodiment will be described. For simplification, the port D in FIG. 1 is omitted from the secondary side conversion circuit.

  FIG. 7 shows a circuit configuration used for the simulation. Assume that the voltage at port A is VA, the voltage at port B is VB, the voltage at port C is VC, VA = 48V, VB = 192V, VC = 14V, and the switching frequency is 50 kHz. The primary side is 12 turns at both ends of the core, and the secondary side is 12 turns at the ends of the core so that the winding ratio of the primary transformer coil and the secondary transformer coil is, for example, 1: 4. Wind the coil one turn at a time. In FIG. 7, it should be noted that there is no magnetic coupling reactor as shown in FIG.

  FIG. 8A and FIG. 8B show the magnetic flux when reactor operation, that is, common mode current is supplied. When the magnetic flux generated by the transformer coil 12a is φu and the magnetic flux generated by the transformer coil 12b is φv, the in-phase magnetic flux generated at the center leg is φcm = φu + φv. The in-phase magnetic flux is a DC magnetic flux having a constant ripple that passes through the core center leg.

  FIG. 9A and FIG. 9B show the magnetic flux when a transformer operation, that is, a reverse-phase current is supplied. When the magnetic flux generated by the transformer coil 12a is φu and the magnetic flux generated by the transformer coil 12b is φv, the magnetic flux generated at the center leg is φdf = (φu−φv) / 2. The anti-phase magnetic flux is an alternating magnetic flux that flows while the direction of change of the magnetic flux is alternately changed clockwise and counterclockwise on the both ends of the core.

  10A to 10D show simulation results. 750 W of power is transmitted from port B to port A.

  FIG. 10A shows voltage waveforms of the primary side voltage Vuv and the secondary side voltage Vαβ. Power transmission in the operation of the isolated converter is controlled by the phase difference between the voltages generated on the primary side and the secondary side of the magnetic element.

  FIG. 10B shows current waveforms of the current icm when the in-phase current is supplied and the current idf when the reverse-phase current is supplied. The current icm when the common-mode current is supplied is icm = iu + iv, which matches the reactor current waveform of the non-insulated converter (boost converter). On the other hand, the current idf at the time of supplying the reverse-phase current is idf = (iu−iv) / 2, which matches the transformer current waveform of the isolated converter.

  FIG. 10C shows the magnetic flux φu generated by the transformer coil 12a and the magnetic flux φv generated by the transformer coil 12b. These two waveforms are combined waveforms of the magnetic flux due to the transformer operation and the magnetic flux due to the reactor operation.

  FIG. 10D shows magnetic flux φcm due to in-phase current change and magnetic flux φdf due to reverse phase current. The magnetic flux due to the in-phase current is φcm = φu + φv, which matches the magnetic coupling reactor magnetic flux waveform when the magnetic elements are used separately. On the other hand, the magnetic flux due to the reverse phase current is φdf = (φu−φv) / 2, which coincides with the center tap transformer magnetic flux waveform when the magnetic elements are separately used. Therefore, the magnetic flux flowing through the magnetic element (integral magnetic element) in this embodiment is a combined waveform of the magnetic flux due to the reactor operation and the magnetic flux due to the transformer operation, and can function as a reactor and a transformer without interfering with each other.

  10 Core, 12a, 12b Primary transformer coil, 14a, 14b Secondary transformer coil, 16a, 16b Reactor coil, 100 control circuit, 120 power conversion circuit.

Claims (2)

A core with a central leg and legs on both ends;
A first primary transformer coil and a first secondary transformer coil wound around one of the leg portions at both ends;
A second primary transformer coil and a second secondary transformer coil wound around either one of the leg portions at both ends;
With
The first primary transformer coil and the second primary transformer coil are connected in series,
The first secondary transformer coil and the second secondary transformer coil are connected in series,
A reactor coil is not wound around the central leg of the core,
A reactor operation is performed by supplying an in-phase current to the first primary transformer coil and the second primary transformer coil, and the first primary transformer coil and the second primary transformer are operated. A transformer-reactor-integrated magnetic element characterized in that a transformer operates by supplying a reverse-phase current to a coil. A primary side conversion circuit comprising a left arm and a right arm between a primary positive electrode bus and a primary negative electrode bus, each of the left arm and the right arm comprising two switching transistors connected in series. The first primary transformer coil and the second primary transformer coil are connected in series between the connection point of the two switching transistors of the left arm and the connection point of the two switching transistors of the right arm. A secondary conversion circuit;
A secondary side conversion circuit comprising a left arm and a right arm between a secondary positive bus and a secondary negative bus, the left arm and the right arm each comprising two switching transistors connected in series. A first secondary transformer coil and a second secondary transformer coil are connected in series between a connection point of the two switching transistors of the left arm and a connection point of the two switching transistors of the right arm. A secondary conversion circuit;
A control circuit for controlling switching of the switching transistors of the primary side conversion circuit and the secondary side conversion circuit;
With
The first primary-side transformer coil and the first secondary-side transformer coil are wound around either one of the leg portions at the both ends of the core including the center leg portion and the leg portions at both ends,
The first secondary transformer coil and the second secondary transformer coil are wound around either one of the leg portions of the both ends of the core,
A reactor coil is not wound around the central leg of the core,
A reactor operation is performed by supplying an in-phase current to the first primary transformer coil and the second primary transformer coil, and the first primary transformer coil and the second primary transformer are operated. A power conversion circuit system characterized in that a transformer operates by supplying a reverse-phase current to a coil.