JP2012069997A - Power module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin, compact, lightweight, high-reliability, high-performance, and reduced-cost power module.SOLUTION: The power module includes a plurality of IGBTs 3a-3m; a plurality of driving circuits 42 for individually driving the IGBTs 3a-3m; a plurality of driving power supply circuits for individually supplying electric power to the driving circuits 42; and a printed circuit board 30 having the driving circuits 42 and the driving power supply circuits mounted thereon. Each of the driving power supply circuits includes a power transformer 50 for transmitting electric power. The power transformer 50 is constructed of primary side and secondary side coil patterns 70a and 70b disposed on the printed circuit board 30; and a core 71 which is attached to the printed circuit board 30, and establishes electromagnetic coupling with the coil patterns 70a and 70b.

Description

  The present invention relates to a power module in which a plurality of power semiconductor elements and a plurality of drive circuits are integrated.

  In a conventional power module (for example, Patent Document 1), in a power supply circuit of a plurality of control circuits for driving and controlling a plurality of power semiconductor elements, a single power transformer composed of a single core and a plurality of winding circuits is provided. Adopted to distribute power from each winding circuit to each control circuit.

JP 2001-156252 A (FIGS. 1 and 3) Japanese Patent No. 3620415 (FIG. 4)

  In such a power module, a series circuit including two or more power semiconductor elements is connected in parallel between a positive line and a negative line. Since the drive timing and drive reference voltage of each power semiconductor element are generally different, it is necessary to provide a plurality of drive circuits corresponding to each power semiconductor element. Therefore, as the number of power semiconductor elements increases, the number of drive circuits also increases accordingly, so the number of winding circuits of the power transformer must be increased. As a result, a large number of output terminals are required to generate a large number of mutually isolated outputs, and a large bobbin is required, resulting in an increase in the size of the power transformer.

  In a power module incorporating a large winding transformer, the height of the module itself increases due to the height of the winding transformer. Moreover, when the power module terminal for connecting with an external circuit is arrange | positioned at the module upper part, the connection line to a power module terminal becomes long and may cause a deterioration of an electrical property.

  In addition, general winding transformers are composed of cores, bobbins, windings made of insulated copper wires, etc., but the cores and insulated conductors are heavy, so in power modules used for in-vehicle use, etc. May be damaged.

  A method of reducing the mass and size of each winding transformer by distributing the winding transformer to multiple small winding transformers is also possible, but if the number of winding transformers increases, the cost of the winding transformer will eventually be increased. Tends to increase significantly and reliability also decreases.

  Further, when each terminal of the winding transformer and the wiring pattern of the printed circuit board are connected by soldering or the like, there is a concern about problems such as solder cracks, and the reliability decreases as the number of winding circuits increases.

  In addition, power modules are generally used in a high heat cycle environment over a wide temperature range, and if thin windings are used to reduce the size of the winding transformer, disconnection failure of the windings due to heat cycles occurs. It becomes easy. In addition, since the small winding transformer is small in size, it is difficult to obtain a sufficient withstand voltage between the windings, and is not suitable for a high voltage power module.

  On the other hand, in order to ensure a high withstand voltage between the power semiconductor element and the drive circuit, an isolation circuit such as a gate drive photocoupler or a gate drive winding transformer is generally employed. Even when such an insulating transformer is used, the above-described problems are concerned.

  In order to solve the above-described problems, an object of the present invention is to provide a power module that is thin, small, lightweight, highly reliable, high performance, and low cost.

In order to achieve the above object, a power module according to the present invention includes a plurality of power semiconductor elements,
A plurality of drive circuits for individually driving each power semiconductor element;
A plurality of drive power supply circuits for supplying power to each drive circuit individually;
Each drive circuit and a printed circuit board on which each drive power supply circuit is mounted,
Each drive power circuit includes a power transformer for transmitting power,
The power transformer is composed of primary and secondary coil patterns disposed on a printed circuit board, and a core member that is mounted on the printed circuit board and electromagnetically couples with the primary and secondary coil patterns.
The core member is formed of a magnetic and conductive material,
The printed circuit board is arranged to cover each power semiconductor element.

The power module according to the present invention includes a plurality of power semiconductor elements,
A plurality of drive circuits for individually driving each power semiconductor element;
And a printed circuit board on which each drive circuit is mounted,
Each drive circuit includes an insulating transformer for transmitting a drive signal of the power semiconductor element,
The insulating transformer includes a primary side and a secondary side coil pattern disposed on a printed circuit board, and a core member that is mounted on the printed circuit board and electromagnetically couples with the primary side and the secondary side coil pattern.
Each power semiconductor element and each insulation transformer corresponding to each power semiconductor element are arranged corresponding to the shortest distance.

  According to the present invention, the winding circuit of the power transformer and the insulating transformer is configured by the coil pattern of the printed circuit board, so that the transformer can be reduced in thickness, reduced in size and weight, and the number of soldering points can be reduced. , Heat cycle resistance and transformer pressure resistance can be improved. Furthermore, the cost of the power module can be reduced, the deterioration of electrical characteristics can be suppressed, and the reliability can be greatly improved.

  Further, the core member is formed of a magnetic and conductive material, and the printed circuit board is disposed so as to cover each power semiconductor element, thereby obtaining a radiation noise shielding effect.

  Further, each power semiconductor element and each insulating transformer corresponding to each power semiconductor element are arranged corresponding to the shortest distance, thereby providing excellent noise resistance and stable operation.

It is a disassembled perspective view which shows schematic structure of the power module which concerns on this invention. An example of the circuit diagram in a base substrate is shown. An example of the circuit diagram in a printed circuit board is shown. An example of the structure of the sheet transformer 70 is shown, FIG. 4A is a plan view, and FIG. 4B is a cross-sectional view. It is a circuit diagram which shows an example of the drive circuit of the power module which concerns on 2nd Embodiment of this invention. FIG. 6A is a plan view and FIG. 6B is a cross-sectional view showing another example of the sheet transformer 70.

Embodiment 1 FIG.
FIG. 1 is an exploded perspective view showing a schematic structure of a power module according to the present invention. The power module includes a base substrate 1, a printed circuit board 30, a case member 20, and the like.

  The base substrate 1 has a wiring pattern formed on an electrically insulating layer having excellent heat dissipation performance, and is composed of, for example, an aluminum substrate or a ceramic substrate. On the base substrate 1, a plurality of power semiconductor elements, for example, an IGBT (Insulated Gate Bipolar Transistor) 3, a plurality of diodes 4, a plurality of connection terminals 13, and the like are mounted. The base substrate 1 is usually mounted on an external heat sink (not shown).

  The case member 20 is provided so as to surround the base substrate 1 in order to hold the base substrate 1 and the printed circuit board 30 at a predetermined interval.

  A plurality of drive circuits for individually driving the IGBT 3 and a plurality of drive power supply circuits for individually supplying power to each drive circuit are mounted on the printed circuit board 30, as shown in FIG. In addition, various circuit elements such as an oscillation circuit 37, a MOSFET 38, a bypass capacitor 39, a rectifier circuit 41, a drive circuit 42, and a power transformer 50 are mounted.

  A large number of connection terminals 13 are erected on the base substrate 1 to electrically connect the wiring pattern of the base substrate 1 and the wiring pattern of the printed circuit board 30 with the printed circuit board 30 stored in the case member 20. Used.

  A number of module terminals 21 are arranged on the case member 20 and are used for electrical connection with an external circuit.

  FIG. 1 shows a state in which the printed board 30 is removed upward in order to explain the internal structure. However, the actual printed board 30 is housed inside the case member 20 and the base board 1 and A resin sealing material 25 is injected into the internal space between the printed circuit board 30 and the upper surface side of the printed circuit board 30, and the entire module is molded and sealed.

  FIG. 2 shows an example of a circuit diagram of the base substrate 1. Here, a converter that converts a three-phase (U-phase, V-phase, W-phase) power input Pin into a three-phase (R-phase, S-phase, T-phase) power output Pout is exemplified. The present invention is also applicable to various inverters.

  Between the positive line Lp and the negative line Ln, a series circuit composed of IGBTs 3a and 3g for switching the U phase, a series circuit composed of IGBTs 3b and 3h for switching the V phase, and a series composed of IGBTs 3c and 3i for switching the W phase. Further, a series circuit composed of IGBTs 3d and 3j for switching the R phase, a series circuit composed of IGBTs 3e and 3k for switching the S phase, and a series circuit composed of IGBTs 3f and 3m for switching the T phase are connected. Diodes 4a to 4m are respectively connected in reverse parallel to the IGBTs 3a to 3m.

  The power input Pin and the power output Pout are transmitted / received to / from an external circuit via the module terminal 21 shown in FIG.

  The gates and emitters of the IGBTs 3 a to 3 m are individually connected to the connection terminals 13 shown in FIG. 1, and drive signals Sa are transmitted from a plurality of drive circuits mounted on the printed circuit board 30 via the individual connection terminals 13. ~ Sm are supplied separately.

  FIG. 3 shows an example of a circuit diagram of the printed circuit board 30. The printed circuit board 30 includes a plurality of drive circuits 42 for outputting drive signals Sa to Sm of the IGBTs 3 a to 3 m and a plurality of drive power supply circuits for individually supplying power to the drive circuits 42. Installed. FIG. 3 shows a circuit diagram for six systems of drive signals Sa to Sf, and the remaining drive signals Sg to Sm are omitted because they have the same circuit configuration.

  Each driving power supply circuit includes a power transformer 50 and a rectifier circuit 41. The primary side coil 50a of each power supply transformer 50 is connected in common, and the individual rectifier circuit 41 is connected to the secondary side coil 50b. Each rectifier circuit 41 includes a rectifier diode 41a and a smoothing capacitor 41b. The DC voltage from each rectifier circuit 41 is individually supplied to each drive circuit 42.

  Between the positive line connected to the positive electrode Vin + of the external power source and the negative line connected to the negative electrode Vin− of the external power source, a bypass capacitor 39, an oscillation circuit 37, and a primary side coil 50a of each power transformer 50 are provided. And a series circuit composed of MOSFET 38 is connected.

  The oscillation circuit 37 generates a pulse having a predetermined cycle and a predetermined duty ratio. The MOSFET 38 switches the current flowing in the primary coil 50a of each power transformer 50 in a pulsed manner in accordance with the pulse from the oscillation circuit 37. Each power transformer 50 converts the voltage into a voltage corresponding to the winding ratio of the primary coil 50 a and the secondary coil 50 b and supplies the voltage to each rectifier circuit 41. The bypass capacitor 39 prevents pulsed current from leaking out as noise.

  Each drive circuit 42 includes a photocoupler 42 a for optical isolation, receives a control signal from an external control circuit such as a microprocessor, outputs individual drive signals Sa to Sm, and passes through the connection terminal 13. It supplies to the gate and emitter of each IGBT3a-3m. .

  4A and 4B show an example of the structure of a sheet transformer 70 that can be used as the power transformer 50. FIG. 4A is a plan view and FIG. 4B is a cross-sectional view. The sheet transformer 70 includes a primary coil pattern 70a disposed on the first surface (for example, the front side surface) of the printed circuit board 30 and a secondary side disposed on the second surface (for example, the back surface) of the printed circuit board 30. The coil pattern 70b and the core 71 that is electromagnetically coupled to both the coil patterns 70a and 70b.

  Three through holes 31 are formed in the printed circuit board 30 so as to be close to both the coil patterns 70a and 70b. The core 71 is, for example, divided in advance into E-shaped split cores. When the split cores are attached to the through holes 31 from both sides of the printed circuit board 30, the core 71 is obtained by integrating the split cores.

  By using such a sheet transformer 70 as the power transformer 50, the transformer can be thinned and reduced in size and weight. Therefore, compared to a power module using a conventional large transformer, the entire module is reduced in thickness, size and weight. Is achieved.

  In addition, by forming the coil patterns 70a and 70b on the printed circuit board 30, it is possible to reduce the number of soldering points, and in addition to vibration resistance and heat cycle resistance compared to a conventional transformer manufactured by winding an ultrafine wire around a bobbin. Performance and transformer withstand voltage can be greatly improved.

  Further, in the conventional winding transformer, it has been difficult to increase the withstand voltage between the primary winding and the secondary winding due to restrictions on the shape of the bobbin, but in the power transformer 50 according to the present invention, the sheet transformer In 70, the coil patterns 70a and 70b are arranged via the electrical insulating layer of the printed circuit board 30, so that the withstand voltage between the primary winding and the secondary winding can be increased.

  In addition, when downsizing a conventional winding transformer configured by fitting a core to a bobbin, an inexpensive outsert bobbin cannot be used, and an expensive insert bobbin must be used. An inexpensive power module can be realized because no bobbin is required and no wire for winding is required.

  Also, when using multiple conventional winding transformers, increasing the pattern area ratio of the printed circuit board on which the drive circuit is mounted increases the heat capacity during reflow soldering of the printed circuit board. The soldering portion of the winding wound around the bobbin may be remelted, and the soldering quality may be adversely affected. For this reason, it is difficult to increase the pattern area ratio of the printed circuit board.

  On the other hand, in the present invention, there is no soldering portion of the transformer, the ratio of the pattern area of the printed circuit board can be easily increased, and a ground pattern with a large area can be easily secured. As a result, radiation noise in the power module can be effectively shielded by a large ground pattern, and radiation noise can be suppressed.

  The area where the coil pattern is arranged has a lower ground pattern area ratio, but the shielding effect can be obtained by forming the core to be mounted in the vicinity of the coil pattern from a magnetic and conductive material. The shield effect can be maintained.

  Furthermore, in this embodiment, as shown in FIG. 1, a large number of connection terminals 13 are arranged on the base substrate 1 in four places. For example, as shown in FIG. 2, the connection terminal 13 that transmits the drive signals Sa to Sc, the connection terminal 13 that transmits the drive signals Sd to Sf, the connection terminal 13 that transmits the drive signals Sg to Si, and the drive signal The connection terminals 13 for transmitting Sj to Sm are distributed at four locations.

  In the printed circuit board 30, the drive circuit 42 that supplies the drive signals Sa to Sc and the drive power supply circuit related thereto, the drive circuit 42 that supplies the drive signals Sd to Sf, and the drive power supply circuit related thereto The drive circuit 42 for supplying the drive signals Sg to Si and the drive power supply circuit related thereto, and the drive circuit 42 for supplying the drive signals Sj to Sm and the drive power supply circuit related thereto are respectively connected to the corresponding connection terminals. 13 is arranged in the vicinity.

  With this arrangement, the wiring distance from the secondary coil 50b of the power transformer 50 to the gates and emitters of the IGBTs 3a to 3m can be shortened as much as possible. As a result, the power supply line to the drive circuit 42 in which noise is likely to be mixed or the gate drive line in which problems such as gate oscillation are likely to occur is shortened, so that a power module having excellent noise resistance and operating stably can be realized.

  In the above description, an example in which a total of twelve power transformers 50 are arranged for every twelve drive circuits 42 that drive the respective IGBTs 3a to 3m is shown. However, the IGBTs 3g to 3m arranged on the negative line Ln side are shown. The emitters are commonly connected, and the drive reference voltages of these IGBTs 3g to 3m are common. Therefore, the power supply transformer 50 and the rectifier circuit 41 related to a total of six drive circuits 42 that drive the IGBTs 3g to 3m can be shared. For example, one power transformer 50 and one rectifier circuit 41 supply power to 2 to 6 drive circuits 42, thereby reducing the number of components.

  If the power capacity is insufficient at this time, two or more power transformers 50 can be connected in parallel. It is also possible to provide two or more secondary coils 50 b in one power transformer 50 and supply power to two or more drive circuits 42 individually. In addition, when providing the several coil pattern 70b in the sheet | seat transformer 70 as the secondary side coil 50b, in order not to increase the number of layers of the printed circuit board 30, the secondary side coil pattern 70b of 2-3 circuits is preferable.

  Moreover, in this embodiment, although the example which used IGBT as a power semiconductor element was shown, the effect similar to this invention is acquired also when other power semiconductor elements, such as a transistor and MOSFET, are used instead,

Embodiment 2. FIG.
FIG. 5 is a circuit diagram showing an example of a power module drive circuit according to the second embodiment of the present invention. The overall structure of the power module according to this embodiment is the same as that shown in FIG. The circuit diagram of the base substrate 1 is also the same as that shown in FIG.

  Referring to FIG. 5, printed circuit board 30 includes a plurality of gate transformers 60 for outputting drive signals Sa to Sm of IGBTs 3 a to 3 m and a plurality of gate transformer drive circuits for driving each gate transformer 60. 43 is mounted. FIG. 5 shows a circuit diagram for six systems of drive signals Sa to Sf, and the remaining drive signals Sg to Sm are omitted because they have the same circuit configuration.

  Each gate transformer 60 is configured as an insulating transformer that electrically insulates the drive circuit side and the power semiconductor element side, the gate transformer drive circuit 43 is disposed in the primary side coil 60a, and the secondary side coil 60b includes the IGBTs 3a to 3b. Connected to 3m gate and emitter.

  The gate transformer driving circuit 43 is configured as a buffer circuit, amplifies the differential control signals Vd + and Vd− from an external control circuit such as a microprocessor, shapes the waveform, and then supplies the pulsed current to the gate transformer 60.

  The sheet transformer 70 shown in FIG. 4 can also be used for the gate transformer 60 according to the present embodiment. By using such a sheet transformer 70 as the gate transformer 60, the transformer can be thinned and reduced in size and weight. Therefore, compared to a conventional power module using a large transformer, the entire module is reduced in thickness and reduced in size and weight. Is achieved.

  In addition, by forming the coil patterns 70a and 70b on the printed circuit board 30, it is possible to reduce the number of soldering points, and in addition to vibration resistance and heat cycle resistance compared to a conventional transformer manufactured by winding an ultrafine wire around a bobbin. Performance and transformer withstand voltage can be greatly improved.

  Similarly to the first embodiment, each gate transformer 60 is arranged in the vicinity of the vertical direction corresponding to each IGBT 3a to 3m, so that the gate of each IGBT 3a to 3m and the gate of each IGBT 3a to 3m from the secondary coil 60b of each gate transformer 60 can be obtained. The wiring distance to the emitter can be shortened as much as possible. As a result, the gate drive line, which is likely to cause problems such as noise mixing and gate oscillation, is shortened, so that it is possible to realize a power module that has excellent noise resistance and operates stably.

Embodiment 3 FIG.
FIG. 6 shows another example of the sheet transformer 70, FIG. 6 (a) is a plan view, and FIG. 6 (b) is a cross-sectional view. In the present embodiment, the printed circuit board 30 is configured by a multilayer substrate that is laminated in the order of an electrical insulation layer, a first conductor layer, an electrical insulation layer, a second conductor layer, and an electrical insulation layer.

  The sheet transformer 70 includes a primary coil pattern 70a disposed on the second conductor layer of the printed circuit board 30, a secondary coil pattern 70b disposed on the first conductor layer of the printed circuit board 30, and both coil patterns 70a. , 70b and a core 71 that is electromagnetically coupled.

  Three through holes 31 are formed in the printed circuit board 30 so as to be close to both the coil patterns 70a and 70b. The core 71 is, for example, divided in advance into E-shaped split cores. When the split cores are attached to the through holes 31 from both sides of the printed circuit board 30, the core 71 is obtained by integrating the split cores.

  By using such a sheet transformer 70 as the power transformer 50 shown in FIG. 3 or the gate transformer 60 shown in FIG. 5, the transformer can be thinned and reduced in size and weight, so that power using a conventional large transformer is used. Compared to a module, the entire module can be made thinner and smaller and lighter.

  In addition, by forming the coil patterns 70a and 70b on the printed circuit board 30, it is possible to reduce the number of soldering points, and in addition to vibration resistance and heat cycle resistance compared to a conventional transformer manufactured by winding an ultrafine wire around a bobbin. Performance and transformer withstand voltage can be greatly improved.

  In particular, in this embodiment, by arranging both the coil patterns 70a and 70b on the inner layer side of the multilayer printed board, not only between the coil patterns 70a and 70b but also between the core 71 and the coil patterns 70a and 70b. Since the electric insulating layer is interposed, not only the dielectric strength between the coils but also the dielectric strength between the core and the coil can be secured high. Therefore, when placing electronic components near the core 71, it is not necessary to provide a special insulation design such as ensuring a creepage distance between the core and components, so that high-density mounting of electronic components, thinning of the entire module, reduction in size and weight are achieved. Is planned.

  6 shows an example in which both the primary side coil pattern 70a and the secondary side coil pattern 70b of the sheet transformer 70 are provided as the inner layer sheet coils on the inner layer of the printed board, but the primary side coil patterns 70a and 2 are provided. One of the secondary coil patterns 70b is formed as an inner layer sheet coil, the other coil pattern is provided on the substrate surface, and a gap for electrical insulation is provided between the other coil pattern and the core 71. A similar effect can be obtained.

1 base substrate, 3, 3a-3m IGBT, 4, 4a-4m diode,
13 connection terminals, 20 case members, 21 module terminals,
25 resin sealing material, 30 printed circuit board, 31 through hole, 37 oscillation circuit,
38 MOSFET, 39 Bypass capacitor, 41 Rectifier circuit,
42 drive circuit, 43 gate transformer drive circuit, 50 power transformer,
60 gate transformer, 70 sheet transformer,
70a, 70b Coil pattern, 71 cores.

Claims (3)

A plurality of power semiconductor elements;
A plurality of drive circuits for individually driving each power semiconductor element;
A plurality of drive power supply circuits for supplying power to each drive circuit individually;
Each drive circuit and a printed circuit board on which each drive power supply circuit is mounted,
Each drive power circuit includes a power transformer for transmitting power,
The power transformer is composed of primary and secondary coil patterns disposed on a printed circuit board, and a core member that is mounted on the printed circuit board and electromagnetically couples with the primary and secondary coil patterns.
The core member is formed of a magnetic and conductive material,
A printed circuit board is disposed so as to cover each power semiconductor element. A plurality of power semiconductor elements;
A plurality of drive circuits for individually driving each power semiconductor element;
And a printed circuit board on which each drive circuit is mounted,
Each drive circuit includes an insulating transformer for transmitting a drive signal of the power semiconductor element,
The insulating transformer includes a primary side and a secondary side coil pattern disposed on a printed circuit board, and a core member that is mounted on the printed circuit board and electromagnetically couples with the primary side and the secondary side coil pattern.
Each power semiconductor element and each insulation transformer corresponding to each power semiconductor element are arranged corresponding to the shortest distance, respectively. The printed circuit board is composed of a multilayer printed circuit board,
The power module according to claim 1 or 2, wherein both the primary side and secondary side coil patterns are arranged on the inner layer side of the multilayer printed circuit board.

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