JP2012178937A - Power conversion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion apparatus which reduces a radiation noise due to a switching noise of a power semiconductor element.SOLUTION: In the power conversion apparatus which includes a power module having a power semiconductor element for converting a DC power into an AC power, a positive electrode wire and a negative electrode wire for supplying the DC power to the power module, a driver circuit substrate for outputting a control signal for controlling driving of the power semiconductor element, a control circuit substrate for generating an operation signal to be transmitted to the driver circuit substrate, and a metal member for electrically connecting the driver circuit substrate or the control circuit substrate with the ground of a vehicle, the metal member is arranged at such a position that electromagnetic noises of the positive electrode wire and the negative electrode wire are negated.

Description

  The present invention relates to a power converter.

The inverter device is a device that generates AC power from DC power such as a battery, and is used in, for example, a so-called automotive power electronics system for obtaining mechanical energy from electrical energy in an electric vehicle.
The inverter device includes a switching element made of a power semiconductor element modularized in a housing (referred to as a power module), a driver circuit for driving a control signal for turning on / off the switching element, and a smoothing capacitor. And a control circuit for generating an operation signal to be sent to a driver circuit or the like.

  When switching a DC power supply at high speed, the switching element generates a surge current / voltage along with a sudden voltage / current change, and becomes a source of electromagnetic noise. Therefore, as a prior art, in Patent Document 1 (Japanese Patent Laid-Open No. 18-224045), by disposing a conductive shield plate electrically insulated from the housing between the control circuit board and the power module, A method for preventing switching noise generated by on / off operations of switching elements in a power module from being superimposed on a control circuit board is disclosed.

JP-A-18-224045

  In Patent Document 1 (Japanese Patent Laid-Open No. 18-224045), a conductive shield plate that is electrically insulated from the housing is disposed between a control circuit board and a power module, and a switching element in the power module is provided. There is shown a technique for preventing switching noise generated by the on / off operation of the signal from being superimposed on a control circuit board and increasing electromagnetic radiation to the outside. However, there are problems that the cost of the inverter device increases and the size cannot be reduced due to an increase in the number of shield members.

  The present invention solves the above problems. Moreover, the power converter device provided with the structure which suppresses the noise electric current or voltage which propagates the control wiring connected with an external apparatus and mixes in an apparatus cheaply and compactly is provided.

  A power module having a power semiconductor element that converts DC power into AC power, a positive and negative wiring that supplies DC power to the power module, and a control circuit board that outputs a control signal that controls driving of the power semiconductor element A power conversion device comprising a metal member that electrically connects the control circuit board and the vehicle ground, wherein the metal member is disposed at a position where electromagnetic noises of the positive electrode wiring and the negative electrode wiring cancel each other. Power conversion device.

  ADVANTAGE OF THE INVENTION According to this invention, the noise resulting from the switching noise of a power semiconductor element can be reduced in a power converter device.

It is explanatory drawing for demonstrating the internal structure of an inverter apparatus. In the structure which does not apply this invention, it is explanatory drawing of the cross-section which shows that a potential fluctuation arises in a base board by switching noise. In the structure to which this invention is applied, it is explanatory drawing of the cross-section which shows the method of suppressing the electric potential fluctuation | variation which arises in a base board by switching noise. In order to show the effect of this invention, it is explanatory drawing which shows a mode that the potential fluctuation difference which arises in a base board was analyzed by the three-dimensional electromagnetic field simulation. It is a figure which shows the analysis result of the electric field strength at the time of not applying this invention. It is a figure which shows the analysis result of the electric field strength at the time of applying this invention. It is a figure which shows the analysis result of the electric field strength at the time of applying this invention. It is a graph of the electric field strength in the line B of the driver circuit base board 32 of FIG. It is explanatory drawing of the cross-section which shows the method of suppressing the electric potential fluctuation which arises in a base board by the switching noise in Example 2 to which this invention is applied. It is explanatory drawing of sectional structure which shows the method of preventing malfunctioning of the control circuit board 41 by the switching noise in Example 2 to which this invention is applied.

FIG. 1 is an explanatory diagram for explaining the internal configuration of the inverter device.
This inverter device 1 is mainly mounted in a power electronics system for automobiles in an electric vehicle. The automotive power electronics system includes a battery for supplying direct current power, an inverter device that converts direct current to alternating current, and a motor that obtains rotational force from the electrical output of the inverter device.
In such a power electronics system for automobiles, the inverter device is turned on and off by the signal from the driver circuit board stored in the housing to turn on and off the switching element of the power module, and is desired in the motor that is the driving source of the automobile. AC power is generated to obtain the rotational force. The motor obtains rotational force by an electromagnetic action by the AC power output from the inverter device in this way.

As shown in FIG. 1, the inverter device 1 according to the present embodiment includes a power module 13 including at least one switching element in a housing 11, a driver circuit board 31 that controls the power module 13, and a smoothing capacitor module. 17 and a control circuit board 41 for generating an operation signal to be sent to a driver circuit or the like.
The power module 13 is usually composed of a plurality of switching elements in order to convert direct current into alternating current. Examples of the switching element include a thyristor, an IGBT, and a power transistor.
The driver circuit board 31 is connected to the power module 13 by the signal line 19. And the control signal for switching the switching element in the power module 13 is output.

The control circuit board 41 is connected to the driver circuit board 31 by a signal line 33. Then, an operation signal for controlling the motor is generated and output to the driver circuit 31 and the like.
The control circuit board 41 may be the same board instead of the driver circuit board 31 and the control circuit board base plate 32 and the driver circuit board base plate 42 may be shared.
The housing 11 is made of a conductive member and has a role of shielding noise (mainly electromagnetic wave noise) propagating from the outside.
In the housing 11, a power supply line 21 a from a positive electrode terminal (not shown) of a battery (not shown) that is a DC power source is connected to the first conductive member 22.
A power supply line 21 b from the negative terminal (not shown) of the battery is connected to the second conductive member 23. Moreover, the capacitor | condenser module 17 for smoothing the direct-current power supplied to an inverter apparatus from a battery is provided. The capacitor module 17 is connected between the power supply line 21 and the power module 13 by being connected to the first conductive member 23 and the second conductive member 23.

  When the switching element of the power module 13 is turned on / off by a signal from the driver circuit board 31, switching noise is generated, and the switching noise flows to the first conductor plate 22 and the second conductor plate 23, and the first conductor Switching noise propagates to the driver circuit base plate 32 and the control circuit base plate 42 via the parasitic capacitance 50 of the plate 22 and the second conductor plate 23, the driver circuit base plate 32 and the control circuit base plate 42, and When noise is conducted through the housing 11 or the control circuit board 41, electromagnetic noise radiated to the outside may increase, or the driver circuit board 31 or the control circuit board 41 may malfunction.

FIG. 2 is an explanatory diagram of a cross-sectional structure showing that a potential fluctuation occurs in the base plate due to switching noise in a structure to which the present invention is not applied.
In this embodiment, the first conductor plate 22, the second conductor plate 23, and the driver circuit board 31 have a hierarchical structure, and the ground of the driver circuit board 31 is connected to the driver circuit base plate 32 by a screw member 34. Electrically connected. The screw member 34 is a conductive member.

Since switching noise is generated by the switching element of the power module 13, it is preferable that the power module 13 be arranged away from a weak electrical harness / cable or a substrate that is easily affected by the noise.
However, if the distance between the weak electrical harness / cable or board and the high electrical power module 13, the first conductor plate 22, or the second conductor plate 23 cannot be increased due to a demand for downsizing the inverter device 1, switching is performed. Noise flows through the first conductor plate 22 and the second conductor plate 23, and switching noise propagates through the driver circuit base plate 32 via the parasitic capacitance 50, so that a noise current flows through the driver circuit base plate 32 and the potential is increased. Variations occur.

Next, FIG. 3 is an explanatory diagram of a cross-sectional structure showing a method for suppressing potential fluctuations generated in the base plate due to switching noise in the structure to which the present invention is applied.
In this embodiment, the first conductor plate 22 and the second conductor plate 23 intersect with the driver circuit base plate 32 in the middle of the wiring from FIG. .

Here, when crossing the first conductor plate 22 and the second conductor plate 23 in the middle of the wiring, when a conductor plate is combined with a slit, a direction in which a current flows to the power module 13 to prevent an increase in inductance. Is preferably parallel to the slit.
Further, it is necessary to open an opening that is not electrically connected to the adjacent portions of the first conductive member 22 and the second conductive member 23.
The first conductive plate 22 is connected to the positive terminal 25 of the power module 13, and the second conductive plate 23 is connected to the negative terminal 26 of the power module 13. Accordingly, since currents flow in the opposite directions to the first conductive member 22 and the second conductive member 23, slits are formed in the first conductive plate 22 and the second conductive plate 23 at the lower part of the driver circuit base plate 32. By disposing, bending, and arranging the conductor plates so as to be alternately opposed to each other, a position where electromagnetic noise induced on the driver circuit base plate 32 cancels out occurs.

Thus, by arranging the screw member 34 at a position where electromagnetic noise cancels out, the ground of the driver circuit board 34 can be grounded to a quiet ground with small potential fluctuations. The generation of electromagnetic noise can be suppressed and the malfunction can be prevented without leaving the distance.
Here, not only the driver circuit base plate 32 but also the object for creating a position for canceling the electromagnetic noise caused by the first conductor plate 22 and the second conductor plate 23 is for the purpose of suppressing the electromagnetic noise. , Ground 41 of the control circuit board, and control circuit base plate 42 may be used.
Note that the first conductor plate 22 and the second conductor plate 23 may be formed of conductive members on a circuit board and arranged so that the conductive members are alternately combined through vias.

FIG. 4 is a diagram showing a state in which the potential fluctuation induced in the base plate is analyzed by a three-dimensional electromagnetic field simulation in order to show the effect of the present invention. This is an analysis of the electric field strength induced in the driver circuit base plate 32 when the input is 1 V, the frequency is 1 MHz, and the first conductor plate 22 and the second conductor plate 23 are excited. The switching element is switched at several kHz, and a harmonic component of several MHz propagates from the first conductor plate 22 and the second conductor plate 23 to the driver circuit board 31, the control circuit board 41, and the like by electromagnetic coupling. Therefore, the frequency of noise generated by the first conductor plate 22 and the second conductor plate 23 is determined according to the carrier frequency of the drive signal output from the driver circuit board 31 to the power module 13.
FIG. 5A shows a conductor plate structure to which the present invention is not applied (see FIG. 2), and an electric field strength generated when the driver circuit base plate 32 is disposed above the first conductor plate 22 and the second conductor plate 23. It is a figure which shows the analysis result. Further, FIG. 5B is a combination in which the first conductive plate 22 on the positive electrode side and the second conductive plate 23 on the negative electrode side are crossed and the upper and lower sides are alternately switched, to which the present invention is applied (see FIG. 3). It is a figure which shows the structure of a conductor board, and the analysis result of the electric field strength produced when the driver circuit base board 32 is arrange | positioned on the said 1st conductor board 22 and the 2nd conductor board 23 upper part. FIG. 5C shows a conductor plate in which the number of times the first conductor plate 22 on the positive electrode side and the second conductor plate 23 on the negative electrode side to which the present invention is applied is increased by one from FIG. It is a figure which shows a structure and the analysis result of the electric field strength produced when the driver circuit base board 32 is arrange | positioned on the upper part of the said 1st conductor board 22 and the 2nd conductor board 23. FIG.

FIG. 6 is a graph of the electric field strength at line B of the driver circuit base plate 32 of FIG.
By bending the conductor plate to create a point that cancels out the noise, the peak value is about -3 dB in FIG. 5B compared to FIG. 5A, and the noise of about −20 dB is suppressed at the point where the noise cancels out. It turns out that there is an effect.
In the case of FIG. 5C, the peak value can be reduced by about −6 dB as compared with FIG. 5A, and the noise reduction effect can be further improved by increasing the number of times the conductor plates are alternately combined. .
As described above, the noise induced on the ground of the driver circuit induction board 31 and the driver circuit base 32 by the first conductor plate 22 and the second conductor plate 23 can be reduced without using a shield.

FIG. 7 is an explanatory diagram of a cross-sectional structure illustrating a method for suppressing potential fluctuations that occur in the substrate ground due to switching noise in the second embodiment to which the present invention is applied.
In this embodiment, a first conductor plate 22, a second conductor plate 23, a driver circuit board 31 and a driver circuit base plate 32 are arranged.
The noise induced in the driver circuit base plate 32 cancels out at the midpoint between the first conductor plate 22 and the second conductor plate 23, so that the conductor plate and the base plate can be installed without processing the conductor plate. You can make a point that cancels out noise.
Then, by installing the screw member at a point where noises cancel each other, the driver circuit board 31 can take a substrate ground at a point where the potential fluctuation is small.
Thereby, malfunction due to noise in the circuit can be prevented, and noise radiated to the outside can be reduced.

FIG. 8 is an explanatory diagram of a cross-sectional structure showing a method for preventing malfunction of the control circuit board 41 due to switching noise in the second embodiment to which the present invention is applied.
In this embodiment, the first conductor plate 22, the second conductor plate 23, the control circuit board 41, and a microcomputer for calculating the switching timing of the switching elements of the power module 13 (hereinafter referred to as "microcomputer") are described. 44) or a control circuit base plate 42 is disposed.

When noise is induced in the control circuit base plate 42 and the ground potential of the microcomputer fluctuates, the circuit may malfunction or the operation may become unstable.
Therefore, by arranging the position of the microcomputer 44 on the control circuit board 41 at the midpoint between the first conductor plate 22 and the second conductor plate 23, fluctuations in the power supply voltage of the microcomputer can be suppressed, and the circuit malfunctions. Can be prevented.

DESCRIPTION OF SYMBOLS 1 Inverter apparatus 11 Housing 13 Power module 17 Capacitor module 19 Signal line 21 Power supply line 22 1st conductor board 23 2nd conductor board 24 3rd conductor board 25 Positive electrode terminal 26 Negative electrode terminal 27 Insulating member 31 Driver circuit board 32 Driver circuit base plate 33 Signal line 34 Screw member 35 Base plate potential 41 Control circuit board 42 Control circuit base plate 43 Control harness 44 Microcomputer 50 Parasitic capacitance

Claims (6)

A power module having a power semiconductor element for converting DC power into AC power;
A positive electrode wiring and a negative electrode wiring for supplying DC power to the power module;
A driver circuit board for outputting a control signal for controlling driving of the power semiconductor element;
A control circuit board for generating an operation signal to be sent to the driver circuit board;
A power conversion device comprising the driver circuit board or the control circuit board and a metal member that electrically connects the ground of the vehicle,
The power conversion device according to claim 1, wherein the metal member is disposed at a position where electromagnetic noises of the positive electrode wiring and the negative electrode wiring cancel each other. The power conversion device according to claim 1,
The power conversion device according to claim 1, wherein the metal member is disposed at an equal distance from the positive electrode wiring and the negative electrode wiring. The power conversion device according to claim 1,
A power conversion device, wherein a screw position of a ground of a substrate of the metal member or a harness or a cable is arranged at a position where electromagnetic noises of the positive electrode wiring and the negative electrode wiring cancel each other. In the power converter device in any one of Claims 1 thru | or 3,
The positive electrode wiring and the negative electrode wiring for supplying DC power to the power module are disposed opposite to each other through an insulator, and the positive electrode wiring and the negative electrode wiring intersect with each other in the middle of the wiring, so that the upper and lower sides are switched. The power converter characterized by the above-mentioned. The power conversion device according to claim 4, wherein
A power conversion device comprising: a slit for intersecting the positive electrode wiring and the negative electrode wiring in the middle of the wiring, and a direction in which a current flows to the power module is parallel to the slit. In the power converter device in any one of Claims 1 thru | or 5,
A power conversion device, wherein a microcomputer disposed on the driver circuit board or the control circuit board is disposed at a position where electromagnetic noises of the positive electrode wiring and the negative electrode wiring cancel each other.

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