WO2017158966A1

WO2017158966A1 - Electric power steering drive device

Info

Publication number: WO2017158966A1
Application number: PCT/JP2016/086970
Authority: WO
Inventors: 公輔中野; 村上　哲; 幸司吉瀬; 白木　康博; 和弘多田; 穂隆六分一
Original assignee: 三菱電機株式会社
Priority date: 2016-03-18
Filing date: 2016-12-13
Publication date: 2017-09-21
Also published as: JPWO2017158966A1; JP6444495B2

Abstract

A multilayer substrate provided in this electric power steering drive device is provided with: a heat radiating plate; a first region which is fixed to a first surface of the heat radiating plate and to which a power switching element is mounted; and a second region which is fixed to a second surface of the heat radiating plate and to which a portion of a member constituting a control part is mounted. The heat radiating plate has an extending part that comes into direct contact with a metal housing.

Description

Electric power steering drive device

The present invention relates to a drive device for an electric power steering that applies an assist force to a vehicle steering device by the rotational force of an electric motor.

As is well known, the electric power steering drive device includes an electric motor that generates an auxiliary torque corresponding to the steering torque of the driver applied to the steering wheel of the vehicle, and an electronic control unit that drives the electric motor. The electronic control unit includes a power conversion device configured by a power switching element that supplies power to the electric motor and a control circuit that controls the power switching element, and is fixed integrally to the electric motor.

The electronic control unit in the conventional electric power steering drive device disclosed in Patent Document 1 is composed of a power module housing the power switching element of the power converter and a control circuit for controlling the power switching element as separate components. The power module and the control circuit configured separately are electrically connected using a connector and a connection terminal.

On the other hand, the electronic control unit in the conventional electric power steering drive device disclosed in Patent Document 2 is configured by integrating a power module containing a power switching element and a control circuit using a single multilayer board. Yes. More specifically, power switching elements are respectively disposed on both surfaces of a single resin substrate, that is, on one surface and the other surface of the substrate, and the power conversion device is disposed on the same surface of the substrate. The power switching element and the control circuit component are mixedly arranged. The power switching element and the control circuit components are electrically connected by a wiring pattern made of a conductive material such as copper provided on the substrate. Therefore, a connection member such as a connector or a connection terminal for electrically connecting the power switching element and the control circuit component is not required.

JP2015-134598A JP 2014-34229 A

In the conventional electric power steering drive device disclosed in Patent Document 1, since the power module and the control circuit are configured separately as described above, a connector and a connection terminal for electrically connecting them. A connecting member such as the above is required, which hinders downsizing and space saving of the apparatus.

On the other hand, in the conventional electric power steering driving device disclosed in Patent Document 2, a power switching element through which a relatively large current flows and a control circuit component through which a relatively small current flows are arranged on the same surface of the substrate. Since these are electrically connected by the wiring pattern provided on the substrate, connection members such as connectors and connection terminals for electrically connecting them are not required. However, there are usually parts in the control circuit whose terminal width is narrower than the terminal width of power-related parts, and the wiring pattern for wiring the parts having this narrow-pitch terminal width. Although it is desired to increase the thickness because of the narrow pitch, the thickness cannot be increased beyond a predetermined value due to restrictions on the substrate, and therefore there is a limit to reducing the wiring resistance. There was a problem that the heat generation of the was increased.

Further, the above-mentioned board is usually composed of a multilayer board having a through-hole penetrating the board, and under the influence of the through-hole, a component is placed on the other side which is the back side with respect to one side of the board. In order to avoid reducing the component mounting area on one side of the board as a result of an area where mounting is impossible, and so many parts are mounted on one side of the board, There was a problem that it had to be enlarged.

Furthermore, since the hole diameter of the through hole in the substrate increases as the thickness of the wiring pattern formed of a copper plate or the like increases, a power system having a power switching element and a control system having a control circuit are provided. When configured in a separate residence, the hole diameter of the through hole of the control system board can be made relatively small, whereas when the power system and the control system are configured integrally on a single board, the power system is In order to avoid a reduction in the mounting area of the control system components on the board, which requires a relatively large hole diameter, there is a problem that the board size must be increased. It was.

The present invention has been made to solve the above-mentioned problems in the conventional electric power steering driving apparatus, and an object thereof is to provide an electric power steering equipped with a small and low loss electronic control unit. It is said.

The electric power steering drive device according to the present invention is:
An electric motor for generating an auxiliary torque corresponding to a steering torque applied to the steering system of the vehicle by the driver, and a control unit for controlling the driving of the electric motor, and assisting the driver with the auxiliary torque. An electric power steering drive device,
The electric motor includes a metal casing fixed to an end portion in the axial direction thereof,
The control unit is
A power conversion circuit that has a plurality of power switching elements, and converts DC power from a DC power source mounted in the vehicle into AC power based on the switching operation of the power switching elements and supplies the AC power to the electric motor;
A control unit for controlling the switching operation of the power switching element;
A multilayer board on which at least a part of members constituting the power conversion circuit and the control unit is mounted;
The multilayer substrate is
A heat sink,
A first region fixed to the first surface of the heat sink and at least mounted with the power switching element;
A second region that is fixed to a second surface having a front-back relationship with the first surface of the heat radiating plate and on which at least a part of members constituting the control unit is mounted. And
The heat sink is
An extending portion that is exposed from at least one of the first region and the second region and extends in a direction in which the surface of the heat sink extends;
The extension portion is fixed to the metal casing so that at least a part thereof directly contacts the metal casing.
It is characterized by that.

According to the electric power steering driving apparatus according to the present invention, the control unit has a plurality of power switching elements, and based on the switching operation of the power switching elements, the DC power from the DC power source mounted on the vehicle is obtained. At least a part of a power conversion circuit that converts AC power to supply to the electric motor, a control unit that controls a switching operation of the power switching element, and members that configure the power conversion circuit and the control unit The multilayer substrate is fixed to the first surface of the heat dissipation plate, at least a first region where the power switching element is mounted, and the heat dissipation plate. At least a part of the members constituting the control unit is fixed to a second surface that has a front-back relationship with the first surface. The heat sink is exposed from at least one of the first region and the second region and extends in a direction in which the surface of the heat sink extends. Since the extension part is fixed to the metal casing so that at least a part of the extension part directly contacts the metal casing, the loss of the electronic control unit can be reduced. In addition, since the mounting area on the multilayer substrate can be increased, an electric power steering drive device that can be miniaturized can be obtained.

It is a block diagram which shows the circuit structure of the electric power steering drive device by Embodiment 1 of this invention. It is a schematic sectional drawing which shows the structure of the electric power steering drive device by Embodiment 1 of this invention. It is a schematic sectional drawing which shows the layer structure of the power area | region of an integrated multilayer substrate in the electric power steering drive device by Embodiment 1 of this invention. It is a top view of the resin case in the electric power steering drive device by Embodiment 1 of this invention. It is a schematic sectional drawing which shows the structure of the electric power steering drive device by Embodiment 2 of this invention.

Embodiment 1 FIG.
Hereinafter, an electric power steering driving apparatus according to Embodiment 1 of the present invention will be described with reference to the drawings. 1 is a block diagram showing a circuit configuration of an electric power steering driving apparatus according to Embodiment 1 of the present invention. Fig. 1 shows a configuration example when an n-type MOSFET (Metal-Oxide-Semiconductor FIELD-EFFECT-Transistor) is used as a power switching element, and the free-wheeling diode connected in parallel to the n-type MOSFET indicates a body diode. However, it is not limited to this.

In FIG. 1, the electric power steering drive device 100 includes an electric motor 9 and an electronic control unit 20. The electric power steering drive device 100 is electrically connected to the battery 1 mounted on the vehicle via the power connector 11, and various in-vehicle sensors such as a vehicle running speed signal from the vehicle side via the in-vehicle various sensor connector 12. 14 is input, and a steering torque signal from the torque sensor 15 is input via the torque sensor connector 13.
The torque sensor is provided on a steering shaft or the like of the vehicle, detects steering torque by the driver, and outputs a steering torque signal.

The electric motor 9 is a three-phase brushless motor, and includes, for example, a rotor 92 having field magnetic poles made of permanent magnets, and a stator 91 having three-phase armature windings made of U, V, and W phases. ing. In FIG. 1, the armature winding is indicated by Δ connection, but it may be Y connection. The brushless motor is an example, and may be an induction machine.

The rotation angle of the rotor 92 of the electric motor 9 (sometimes referred to as the rotation angle of the electric motor) is detected by the electronic control unit 20. The rotor 92 of the electric motor 9, which is a three-phase brushless motor, includes a field magnetic pole made of a permanent magnet as described above. As will be described later, the electronic control unit 20 controls the movement of the field magnetic pole. It can be detected by the rotation sensor 84. The rotation sensor 84 is configured by a magnetic sensor or a resolver.

The electronic control unit 20 includes a noise filter 2, a power supply relay unit 3 that is a switch unit that supplies and cuts off battery current, a three-phase bridge circuit 4 that constitutes a power conversion circuit, and a U-phase described later of the three-phase bridge circuit 4

Smoothing capacitors

6u, 6v, 6w connected in parallel to the phase arm, the V-phase arm and the W-phase arm, the motor relay unit 5 which is a switch means for energizing and interrupting the current to the electric motor 9, and the electric motor 9 A shunt resistor circuit 7 for detecting the current flowing through the armature winding, a microcomputer 81, an FET drive circuit 82, a current detection means 83, and a rotation sensor 84 are provided. The shunt resistor circuit 7 includes

shunt resistors

7u, 7v, and 7w described later.

The three-phase bridge circuit 4 includes a U-phase arm composed of a U-phase upper arm and a U-phase lower arm connected in series, a V-phase arm composed of a V-phase upper arm and a V-phase lower arm connected in series, It has a W-phase arm composed of a connected W-phase upper arm and a W-phase lower arm. High-

potential side FETs

41u, 41v, and 41w as power switching elements are connected to the U-phase upper arm, V-phase upper arm, and W-phase upper arm on the high potential side, respectively, and the U-phase on the low potential side Low-

potential side FETs

42u, 42v, and 42w as power switching elements are connected to the lower arm, the V-phase lower arm, and the W-phase lower arm, respectively.

The high potential side FET 41u opens and closes between the U phase output line UL and the positive side input line PL derived from the connection point between the U phase upper arm and the U phase lower arm. The high-potential side FET 41v opens and closes between the V-phase output line VL and the positive-side input line PL derived from the connection point between the V-phase upper arm and the V-phase lower arm. The high-potential side FET 41w opens and closes between the W-phase output line WL and the positive-side input line PL derived from the connection point between the W-phase upper arm and the W-phase lower arm. The low potential side FET 42u opens and closes between the U-phase output line UL and the negative side input line NL. The low potential side FET 42v opens and closes between the V phase output line VL and the negative side input line NL. The low potential side FET 42w opens and closes between the W phase output line WL and the negative side input line NL.

The negative phase side of the U-phase high potential side FET 41u and the positive side of the low potential side FET 42u are connected, and the U phase output line UL connected to the connection portion is the reference potential side of the U phase motor relay FET 5u of the motor relay unit 5 The other end of the motor relay FET 5u is connected to the U-phase winding terminal UT in the stator 91 of the electric motor 9. The negative electrode side of the low potential side FET 42u and one end of the shunt resistor 7u are connected, and the other end of the shunt resistor 7u is connected to the negative electrode side of the smoothing capacitor 6u.

The negative phase side of the V phase high potential side FET 41v and the positive side of the low potential side FET 42v are connected, and the V phase output line VL connected to the connection portion is the reference potential side of the V phase motor relay FET 5v of the motor relay portion 5 The other end of the motor relay FET 5v is connected to the V-phase winding terminal VT in the stator 91 of the electric motor 9. The negative electrode side of the low potential side FET 42v and one end of the shunt resistor 7v are connected, and the other end of the shunt resistor 7v is connected to the negative electrode side of the smoothing capacitor 6v.

The negative phase side of the W-phase high potential side FET 41w and the positive side of the low potential side FET 42w are connected, and the W phase output line WL connected to the connection portion is the reference potential side of the W phase motor relay FET 5w of the motor relay portion 5 The other end of the motor relay FET 5 w is connected to the W-phase winding terminal WT in the stator 91 of the electric motor 9. The negative electrode side of the low potential side FET 42w and one end of the shunt resistor 7w are connected, and the other end of the shunt resistor 7w is connected to the negative electrode side of the smoothing capacitor 6w. The positive side of the high

potential side FETs

41u, 41v, 41w are connected to the positive side of the smoothing

capacitors

6u, 6v, 6w, respectively.

Between the smoothing

capacitors

6u, 6v, 6w of each phase and the high

potential side FETs

41u, 41v, 41w and the low

potential side FETs

42u, 42v, 42w connected to the upper and lower arms of each phase, A snubber circuit may be provided for suppressing a surge voltage when switching is performed. In this case, the snubber circuit may be configured by a capacitor or a circuit in which a resistor and a capacitor are connected. Further, a snubber circuit may be provided in parallel with the high

potential side FETs

41u, 41v, 41w and the low

potential side FETs

42u, 42v, 42, respectively.

The armature winding of the electric motor 9 is connected to the three-phase bridge circuit 4 provided in the electronic control unit 20, the rotation sensor 84 for detecting the rotation position of the rotor 92, and the

shunt resistors

7u, 7v, 7w. A current detection means 83 for detecting a flowing current; a microcomputer 81; an FET drive circuit 82 for outputting a drive signal for controlling the operation of the FET according to a command from the microcomputer 81; a current detection means 83; The FET drive circuit 82 is mounted on the integrated multilayer substrate 200 as will be described later.

The microcomputer 81 calculates the auxiliary torque that the electric motor 9 should output based on the steering torque signal from the torque sensor 15, and the motor current detected by the current detector 83 and the rotation detected by the rotation sensor 84. A target current for generating auxiliary torque by feeding back the rotational position of the child 92 is calculated.

The power relay unit 3 is composed of two

power relay FETs

31 and 32 connected in series with each other, and the source terminal of the power relay FET 31 and the source terminal of the power relay FET 32 are connected. The drain terminal of the power relay FET 31 is connected to the noise filter 2, and the drain terminal of the power relay FET 32 is connected to the positive side of the smoothing

capacitors

6u, 6v, 6w. The gate terminals of the power relay FET 31 and the power relay FET 32 are connected to the FET drive circuit 82.

The microcomputer 81 includes a well-known self-diagnosis function in addition to the AD converter and the PWM timer circuit, etc., and always performs self-diagnosis as to whether the system is operating normally. The FET drive circuit 82 is configured to turn off all of the

power relay FETs

31 and 32 of the section 3 and the

motor relay FETs

5u, 5v and 5w of the motor relay section 5 and to disconnect the connection between the three-phase bridge circuit 4 and the electric motor 9. Is given a directive.

The FET drive circuit 82 drives the

power relay FETs

31 and 32 of the power relay unit 3 and the

motor relay FETs

5u, 5v, and 5w of the motor relay unit 5 based on a command from the microcomputer 81, and a power switching element. The high

potential side FETs

41u, 41v, 41w and the low

potential side FETs

42u, 42v, 42w are driven.

As described above, the microcomputer 81 receives the steering torque information from the torque sensor 15 and the rotation position information of the rotor 92 of the electric motor 9 from the rotation sensor 84. A travel speed signal is input as one of the various sensors 14. Further, the motor current is detected by the current detection means 83 based on the voltage values across the

shunt resistors

7u, 7v, 7w, and the detected motor current is fed back to the microcomputer 81. The microcomputer 81 generates a power steering rotation direction command and a current control amount corresponding to the auxiliary torque based on these information and signals, and inputs each drive signal to the FET drive circuit 82.

The FET drive circuit 82 generates a PWM drive signal when a power steering rotation direction command and a current control amount are input from the microcomputer 81, and the high

potential side FETs

41u, 41v, 41w, which are power switching elements, and a low potential. A voltage is applied to the

side FETs

42u, 42v, 42w. As a result, the electric current from the battery 1 flows to the electric motor 9 through the power connector 11, the noise filter 2, the power relay unit 3, the three-phase bridge circuit 4, and the motor relay unit 5, and a required amount of auxiliary torque is applied in the required direction. Output from the electric motor 9.

At this time, the motor current detected through the shunt resistor and the current detecting means is fed back to the microcomputer 81 and controlled so as to coincide with the motor current command sent from the microcomputer 81 to the FET drive circuit 52.

In FIG. 1, the negative sides of the smoothing

capacitors

6u, 6v, 6w are not directly connected to GND. This minimizes the closed loop between the smoothing

capacitors

6u, 6v, 6w and the upper and lower arms of each phase to reduce the parasitic inductance, and the high

potential side FETs

41u, 41v, 41w and the low

potential side FETs

42u, 42v, 42w. This is to suppress a surge voltage generated when the is switched.

In general, the noise filter 2 is designed to obtain a predetermined performance by using a normal mode filter and a common mode filter together. The noise filter 2 is a normal mode filter or a common mode filter. Alternatively, both a normal mode filter and a common mode filter may be provided, or a filter that integrates the functions of the normal mode filter and the common mode filter may be used.

FIG. 2 is a schematic cross-sectional view showing the configuration of the electric power steering driving apparatus according to Embodiment 1 of the present invention. The electric power steering driving apparatus 100 includes the block circuit configuration shown in FIG. 1 and is configured as shown in FIG. In FIG. 2, a metal casing 101 having a function of a heat sink is disposed at the axially opposite output side end (upper part in FIG. 2) of the electric motor 9 constituted by a three-phase brushless motor. An integrated multilayer substrate 200 is disposed in an upper portion of the body 101 in the axial direction (upper portion in FIG. 2), and smoothing

capacitors

6u, 6v, 6w are disposed in an upper portion in the axial direction of the multilayer substrate 200 (upper portion in FIG. 2). The noise filter 2 is disposed, and the resin case 102 is disposed on the noise filter 2 (the upper portion in FIG. 2).

The resin case 102 has a power system power connector 11 to which a battery 1 mounted on a vehicle as an external DC power source is connected, and a control system torque sensor to which a torque sensor 15 and various in-vehicle sensors 14 are connected. Connector 13 (not shown) and in-vehicle various sensor connectors 12 (not shown) are formed integrally with resin case 102. As the smoothing

capacitors

6u, 6v, 6w, electrolytic capacitors, conductive polymer capacitors, or hybrid capacitors are used.

In the integrated multilayer substrate 200, a power region 23 as a first region, a control region 21 as a second region, and a heat dissipation plate 22 inserted between the power region 23 control region 21 are integrally combined. Configured. The radial end portion of the heat radiating plate 22 includes an extending portion 221 that extends in a radial direction from the radial end portions of the power region 23 and the control region 21, and the extending portion 221 of the heat radiating plate 22. The end surface on the motor side is in contact with the metal casing 101 having a heat sink function. The heat generated in the integrated multilayer substrate 200 is transferred to the extended portion 221 of the heat radiating plate 22 and the metal casing 101.

The power region 23 is a multilayer substrate configured such that wiring is performed by a copper plate having a large thickness exceeding 100 [um]. The control region 21 is a multiphase substrate configured so that wiring is performed with a copper plate having a thin thickness of 100 [um] or less. Therefore, the layer configuration of the control region 21 and the power region 23 is not the same. In addition, the numerical value of the thickness of these copper plates is an example. Moreover, although the thickness of the copper plate currently used is different, the total thickness of the control region 21 and the power region 23 may be the same or different.

Usually, when the control region 21 and the power region 23 have different layer configurations or substrates having different thicknesses, warpage of the substrate becomes a problem. However, since the heat sink 22 is inserted between the power region 23 and the control region 21 in the configuration of FIG. The heat radiating plate 22 is made of a copper plate that is the same as or thicker than the copper plate used for the wiring provided on one layer of the multilayer substrate constituting the power region 23. The heat radiating plate 22 also has an effect of shielding heat from the motor side.

One of the terminals of the smoothing

capacitors

6u, 6v, 6w and the noise filter 2 is connected to the power region 23 through the control region 21 and the heat sink 22. A rotation sensor 84 configured by a magnetic sensor is connected to the power region 23. The magnetic sensor as the rotation sensor 84 only needs to be able to detect the magnetic pole position of the rotor 92 of the electric motor 9 and is not necessarily connected to the power region 23.

In the integrated multilayer substrate 200 configured as described above, the power region 23 and the control region 21 are individually manufactured, and then the power region 23 and the control region 21 are fixed to both surfaces of the heat sink 22 via prepregs. To be integrated. Thereafter, the control area 21 and the power area 23 are wired.

The through-through hole connected only in the power region 23 does not appear on the surface layer of the control region 21 at one end thereof, so that the component mounting area of the control region 21 is increased and the size can be reduced. Further, the through-through hole connected only by the control region 21 does not appear at one end of the through-hole in the power region 23, so that the component mounting area of the power region 23 increases and the size can be reduced. Further, since the wiring in the control region 21 is composed of only a thin copper plate of 100 [um] or less per phase, there is a feature that the diameter of the through hole that is wired in the control region can be reduced.

The microcomputer 81 and the FET drive circuit 82 are connected to the surface layer of the control area 21. The microcomputer 81 and the FET drive circuit 82 are connected by a through through hole in the control region 21. The high

potential side FETs

41u, 41v, 41w and the low

potential side FETs

42u, 42v, 42w as power switching elements are connected to the surface layer of the power region 23. Since the gates and sources of the high-

potential side FETs

41u, 41v, 41w and the low-

potential side FETs

42u, 42v, 42w are connected to the FET drive circuit 82 through through holes in the power region 23, the wiring can be shortened. There can be reduced noise.

As an assembling procedure of the electric power steering drive device 100, the first buffer member 6a is disposed in the portion 1021 of the resin case 102 where the smoothing

capacitors

6u, 6v, 6w are disposed, and the noise filter 2 of the resin case 102 is disposed. The second buffer member 2a is disposed in the portion 1022, and the smoothing

capacitors

6u, 6v, 6w and the noise filter 2 are disposed in the

predetermined portions

1021, 1022 of the resin case 102, and the smoothing

capacitors

6u, 6v, 6w, the height of the noise filter 2 in the axial direction, and the terminal position are determined. Spaces are secured between the upper surfaces of the smoothing

capacitors

6u, 6v, 6w and the resin case 102 in consideration of opening of the explosion-proof valve.

Next, one end of the power connector 11 constituting the connecting portion with the battery 1 as an external power source and the input end 211 of the noise filter 2 are connected. The connection may be welding, soldering, screwing, or press fitting. The other end of the power connector 11 is connected to a connector (not shown) of the battery 1 that is an external power source.

Before the integrated multilayer substrate 200 is placed in the resin case 102, the third buffer member 24 is inserted into the resin case 102. The third buffer member 24 only needs to reduce the thermal resistance of the heat sink 22 and the metal casing 101 as a heat sink, and may be arranged in a ring shape or may be partially arranged.

Next, the smoothing

capacitors

6u, 6v, 6w and the lead wire of the noise filter 2 are passed through a predetermined through-hole provided in the integrated multilayer substrate 200 and soldered in advance to the power region 23 of the integrated multilayer substrate 200. Connect to L-shaped terminal 4b. This connecting portion may be welded, soldered, screwed, or press fit. The through-through hole provided in the integrated multilayer substrate 200 is provided through the control region 21, the heat sink 22 and the power region 23, and the through-through hole provided only in the control region described above. It is a separate body from the through hole provided only in the power region.

In the first embodiment, the smoothing

capacitors

6u, 6v, 6w and the terminals of the noise filter 2 are connected to the integrated multilayer substrate 200 to which the L-shaped terminal 4b is soldered in advance, but the L-shaped terminal 4b is not provided. Alternatively, it may be soldered directly to the land of the integrated multilayer substrate 200.

Next, the metal casing 101 and the resin case 102 are bonded so that the metal casing 101 and the heat dissipation plate of the integrated multilayer substrate 200 are in contact with each other. The metal casing 101 as the heat sink and the resin case 102 may be joined by an adhesive, screwing, or press fitting.

Here, the role of the third buffer member 24 will be described in detail. Ideally, it is desirable that the resin case 102 fixes the heat radiating plate 22 of the integrated multilayer substrate 200 so that the heat radiating plate 22 and the metal casing 101 are in contact with each other. However, manufacturing tolerances actually occur. In the configuration of FIG. 2, it is important to reduce the thermal resistance between the heat radiating plate 22 and the metal casing 101. If the resin case 102 and the metal casing 101 come into contact with each other before the heat radiating plate 22 and the metal casing 101 come into contact with each other, a gap may be formed between the heat radiating plate 22 and the resin case 102, or the resin case 102. However, the integrated multilayer substrate 200 cannot be held by the metal casing 101, and the contact thermal resistance between the heat sink 22 and the metal casing 101 increases.

However, as shown in FIG. 2, the resin case 102 and the metal casing 101 are inserted into the heat sink 22 and the metal by inserting the third buffer member 24 between the extended portion 221 of the heat sink 22 and the resin case 102. The resin case 102 is obtained by compressing and contracting the third buffer member 24 after ensuring the contact between the heat radiating plate 22 and the metal casing 101 without contacting the casing 101 before contacting the casing 101. And the metal casing 101 can be joined.

Next, the role of the second buffer member 2a and the first buffer member 6a will be described in detail. One end face (upper end face in the figure) of the smoothing

capacitors

6u, 6v, 6w and the inner face of the resin case 102 are fixed and / or one end face in the axial direction of the noise filter 2 (see FIG. When the resin case 102 and the metal casing 101 as a heat sink are joined, the integrated multilayer substrate 200 and the smoothing

capacitors

6u, 6v, 6w are connected. And / or a connection portion between the integrated multilayer substrate 200 and the noise filter 2 is stressed.

On the other hand, as in the case of the first embodiment, the second buffer member 2a is inserted between the inner surface of the resin case 102 and one end surface (the upper end surface in the figure) of the noise filter 2 in the axial direction. By inserting the first buffer member 6a between the inner surface of the resin case 102 and one end face (upper end face in the figure) of the smoothing

capacitors

6u, 6v, 6w in the axial direction, the resin case 102 and the metal casing 101 are inserted. When the second buffer member 2a and the first buffer member 6a are compressed and contracted, the stress applied to the connection portion between the L-shaped terminal 4b and the noise filter 2, the L-shaped terminal 4b and the smoothing capacitor It is possible to relieve the stress applied to the connecting portions of 6u, 6v, and 6w.

Preferably, the reaction force of the second buffer member 2 a and the first buffer member 6 a is greater than the reaction force of the third buffer member 24 inserted between the resin case 102 and the extending portion 221 of the heat sink 22. It is preferable to select materials for the second buffer member 2a, the first buffer member 6a, and the third buffer member 24 so as to be smaller. Thereby, there is an effect that the above-described stress can be further alleviated.

Further, the first buffer member 6a is structured so that air can easily escape, so that the explosion-proof valve provided on one end surface (upper end surface in the figure) of the smoothing

capacitors

6u, 6v, 6w in the axial direction is opened. Air in the space is easily removed.

Next, the configuration of the power region 23 in the integrated multilayer substrate 200 will be described. The power region 23 is composed of a multilayer substrate. FIG. 3 is a schematic cross-sectional view showing the layer configuration of the power region of the integrated multilayer substrate in the electric power steering driving apparatus according to Embodiment 1 of the present invention. In FIG. 3, the power region 23 is constituted by a five-layered multilayer substrate, but the present invention is not limited to this.

In FIG. 3, the power region 23 includes a first layer 231 as a surface layer, a second layer 232 provided below the first layer 231 via the prepreg 23a, and a first layer 231 via the prepreg 23a. The third layer 233 provided below the second layer 232, the fourth layer 234 provided below the third layer 233 via the prepreg 23a, and the fourth layer 234 via the prepreg 23a. And a prepreg 23 a provided between the fifth layer 235 and one surface of the heat sink 22. The first to fifth layers 231 to 235 are each made of a copper plate. The prepreg 23a is made of a material that electrically insulates the first to fifth layers 231 to 235 and electrically separates between the fifth layer 235 and the radiator plate 22. Yes. The aforementioned prepreg 23a is configured by impregnating carbon fiber or the like with a resin, for example.

The first layer 231 as the surface layer includes smoothing

capacitors

6u, 6v, 6w, a noise filter 2, high

potential side FETs

41u, 41v, 41w as power switching elements, low

potential side FETs

42u, 42v, 42w, a

shunt resistor

7u, 7v, 7w, and the rotation sensor 84 are connected.

The second layer 232 as the second layer and the third layer 233 as the third layer include an upper arm and a lower arm of each phase of the three-phase bridge circuit 4, and a motor relay in the motor relay unit 5. A wiring pattern for connecting the

FETs

5u, 5v, and 5w is formed.

In the fourth layer 234 as the fourth layer, a wiring pattern from the power supply relay unit 3 to the positive side of the smoothing

capacitors

6u, 6v, 6w is formed. On the fifth layer 235 as the fifth layer, a wiring pattern from the power supply relay unit 3 to the negative side of the smoothing

capacitors

6u, 6v, 6w is formed.

A copper pin 4a1, which is a heat transfer member formed of a material having a good thermal conductivity such as copper, is disposed immediately below each of the high

potential side FETs

41u, 41v, 41w and the low

potential side FETs

42u, 42v, 42w. The end surface of the copper pin 4a1 is in direct contact with one surface (the lower surface in the figure) of the

side FETs

41u, 41v, 41w and the low

potential side FETs

42u, 42v, 42w. The copper pin 4a1 penetrates through the first layer 231, the second layer 232, the third layer 234, and the fifth layer 235, and reaches the surface of the fifth layer on the side of the heat sink 22 side. . The copper pin 4a1 conducts heat generated by the high

potential side FETs

41u, 41v, 41w and the low

potential side FETs

42u, 42v, 42w to the heat radiating plate 22. In addition to the copper pins, normal thermal vias may be used.
Preferably, the prepreg 23a inserted between the fifth layer 235 as the fifth layer and the heat sink 22 is formed of a prepreg thinner than the prepreg 23a inserted between the other layers. Thereby, the thermal resistance between the copper pin 4a1 and the heat sink 22 can be lowered, and the temperature rise of the high

potential side FETs

41u, 41v, 41w and the low

potential side FETs

42u, 42v, 42w can be effectively suppressed. Is possible. Normally, the high-

potential side FETs

41u, 41v, 41w and the low-

potential side FETs

42u, 42v, 42w have a tendency to increase the on-resistance when the temperature rises. Loss can be reduced.

Even if the copper pin 4a1 is configured to protrude in the direction of the heat radiating plate 22 from the surface on the heat radiating plate 22 side of the fifth layer 235 which is the fifth layer in a state where insulation is ensured, the same heat dissipation as described above. An effect is obtained. Preferably, the prepreg 23a inserted between the fifth layer 235 of the fifth layer and the heat radiating plate 22 is formed of a material having high thermal conductivity. As a result, the thermal resistance can be further lowered, the temperature rise can be suppressed, and the heat generation in the high

potential side FETs

41u, 41v, 41w and the low

potential side FETs

42u, 42v, 42w can be reduced. .

The in-vehicle various sensor connectors 12 connected to the in-vehicle various sensors 14 and the torque sensor connector 13 connected to the torque sensor 15 are connected to the integrated multilayer substrate 200, but in that case, are connected to the power region 23. Alternatively, the control area surface-mounted component may be connected to the control area 21.

FIG. 4 is a plan view of a resin case in the electric power steering driving apparatus according to Embodiment 1 of the present invention, and includes a power connector 11 connected to the battery 1 and an in-vehicle connected to various in-vehicle sensors 14. An arrangement of various sensor connectors 12 and a torque sensor connector 13 connected to the torque sensor 15 is shown. As shown in FIG. 4, the power connector 11 is arranged in the vicinity of the top of one semicircular portion of the resin case 102, and the various in-vehicle sensor connectors 12 and the torque sensor connector 13 are arranged in the other semicircle of the resin case 102. It is arrange | positioned at the peripheral part of the both sides on both sides of the top part of a part.

The connection between the stator 91 of the electric motor 9 and the integrated multilayer substrate 200 is performed by connecting the soldered L-shaped terminal 4b to the power region 23 of the integrated multilayer substrate 200 in advance. The connection may be made by welding, screwing, or press-fit in addition to soldering.

The heat sink 22 can also be used for grounding (GND) of the integrated multilayer substrate 200. Since the extended portion 221 of the heat radiating plate 22 is in direct contact with the metal housing 101, it is not necessary to use a connector or a lead wire to connect the heat radiating plate 22 and the metal housing 101, and noise is reduced. Can do.

Preferably, a part of the metal casing 101 as a heat sink is brought into contact with the first layer 231 that is a surface layer of the power region 23 via a heat dissipation sheet made of an insulating material, thereby parasitic resistance of the wiring. The heat due to the loss generated in the heat can be dissipated, and the temperature rise of the wiring pattern can be suppressed.

As described above, the electric power steering drive apparatus according to Embodiment 1 of the present invention can realize a low loss of the electronic control unit and can effectively use the mounting surface of the board. The electric power steering drive device can be reduced in size.

Embodiment 2. FIG.
Next, an electric power steering driving apparatus according to Embodiment 2 of the present invention will be described. FIG. 5 is a schematic cross-sectional view showing a configuration of an electric power steering driving apparatus according to Embodiment 2 of the present invention. The circuit configuration of the electric power steering driving apparatus according to the second embodiment of the invention is the same as that shown in FIG. In FIG. 5, the same reference numerals are given to components that are the same as or equivalent to the configuration shown in FIG. 2. Here, the description will focus on the parts related to the second embodiment.

In the first embodiment described above, the high

potential side FETs

41u, 41v, 41w and the low

potential side FETs

42u, 42v, 42w are respectively formed on the first layer 231 that is the surface layer of the power region 23 in the integrated multilayer substrate 200. The copper pin 4a1 is brought into contact with one surface of the high-

potential side FETs

41u, 41v, 41w and the low-

potential side FETs

42u, 42v, 42w, and heat is radiated to the heat radiating plate 22 through the copper pins 4a1. However, in the second embodiment, the high-

potential side FETs

41u, 41v, 41w and the low-

potential side FETs

42u, 42v, 42w are configured to dissipate heat.

That is, in FIG. 5, one surface (the lower surface in the figure) of the high

potential side FETs

41u, 41v, 41w and the low

potential side FETs

42u, 42v, 42w is a convex portion of the metal casing 101 as a heat sink. The other surface (the upper surface in the figure) directly contacts the first layer 231 that is the surface layer of the power region 23 of the integrated multilayer substrate 200. ing. Therefore, one surface of the high

potential side FETs

41u, 41v, 41w and the low

potential side FETs

42u, 42v, 42w is radiated to the metal casing 101 via the heat radiating sheet 4e, and the other surface is one via the copper pin 4a1. The heat is dissipated by the heat radiating plate 22 of the body-type multilayer substrate 200, and is cooled more effectively. Normally, placing a heat sink on the upper surface of the power switching element becomes a noise source. In this configuration, since the power region 23 and the metal casing 101 face each other, the noise is low because the power switching element is brought into contact with the convex portion of the metal casing 101 that is grounded (GND).

The electric power steering driving apparatus according to each embodiment of the present invention described above embodies at least one of the following inventions.
(1) An electric motor that generates an auxiliary torque corresponding to a steering torque that a driver applies to a steering system of a vehicle, and a control unit that controls driving of the electric motor, and the driver's steering is controlled by the auxiliary torque. An electric power steering drive device for assisting,
The electric motor includes a metal casing fixed to an end portion in the axial direction thereof,
The control unit is
A power conversion circuit that has a plurality of power switching elements, and converts DC power from a DC power source mounted in the vehicle into AC power based on the switching operation of the power switching elements and supplies the AC power to the electric motor;
A control unit for controlling the switching operation of the power switching element;
A multilayer board on which at least a part of members constituting the power conversion circuit and the control unit is mounted;
The multilayer substrate is
A heat sink,
A first region fixed to the first surface of the heat sink and at least mounted with the power switching element;
A second region that is fixed to a second surface having a front-back relationship with the first surface of the heat radiating plate and on which at least a part of members constituting the control unit is mounted. And
The heat sink is
An extending portion that is exposed from at least one of the first region and the second region and extends in a direction in which the surface of the heat sink extends;
The extension portion is fixed to the metal casing so that at least a part thereof directly contacts the metal casing.
An electric power steering drive device.
According to the present invention, it is possible to obtain a drive device for an electric power steering that can reduce the loss of the electronic control unit and can be downsized because the mounting area of the multilayer substrate can be increased. Can do.

(2) The first region and the second region each include a plurality of layers provided with wiring patterns,
The power switching element mounted in the first region is wired by the wiring pattern provided in the layer of the first region,
At least a part of members constituting the control unit mounted in the second region is wired by the wiring pattern provided in the layer of the second region,
The thickness dimension of the wiring pattern provided in at least one layer of the first region is different from the thickness dimension of the wiring pattern provided in at least one layer of the second region. Formed,
The electric power steering drive device according to (1) above, wherein
According to the present invention, it is possible to increase the thickness of the copper layer on the surface layer of the power region, so that the loss in the wiring can be reduced.

(3) The power switching element is placed on a surface layer of the plurality of layers in the first region,
The first region includes a heat transfer member disposed through the plurality of layers,
The heat transfer member is configured to transmit heat generated by the power switching element to the heat radiating plate.
The electric power steering drive device according to (2) above, wherein
According to the present invention, the power switching element can be effectively cooled.

(4) The power switching element is configured such that a surface opposite to a surface facing the multilayer substrate is in contact with the metal casing.
The electric power steering drive device according to any one of (1) to (3) above, wherein:
According to the present invention, the power switching element can be cooled very effectively.

(5) The first region and the second region of the multilayer substrate are respectively
A plurality of layers having wiring patterns;
A prepreg disposed between the plurality of layers,
The prepreg in the first region has a thermal conductivity higher than the thermal conductivity of the prepreg in the second region;
The electric power steering driving apparatus according to any one of (1) to (4) above, wherein:
According to the present invention, the power switching element can be cooled more effectively.

(6) An insulating cover that is fixed to the metal casing and covers at least the multilayer substrate,
The multilayer substrate is mounted with a smoothing capacitor and a noise filter of the power conversion circuit,
The cover is configured to cover the smoothing capacitor and the noise filter, and is in contact with the smoothing capacitor through a first buffer member, and is in contact with the noise filter through a second buffer member. Configured,
The extending portion of the multilayer substrate is exposed from both the first region and the second region and extends in a direction in which the surface of the heat sink extends.
The extension portion is inserted between the metal casing and the cover,
One surface of the extension part abuts on the cover via a third buffer member,
The other surface forming a front-back relationship with the one surface of the extending portion is configured to directly contact the metal housing.
The electric power steering drive device according to any one of (1) to (5) above, wherein:
According to the present invention, it is possible to relieve stress at the connection portion between the smoothing capacitor and the multilayer substrate and at the connection portion between the noise filter and the multilayer substrate.

(7) The reaction force against the compression of the first buffer member and the reaction force against the compression of the second buffer member are configured to be smaller than the reaction force against the compression of the third buffer member.
The electric power steering drive device according to (6) above, wherein
According to the present invention, it is possible to relieve stress at least at the connection portion between the smoothing capacitor and the multilayer substrate and at the connection portion between the noise filter and the multilayer substrate.

As described above, according to the electric power steering driving apparatus according to Embodiment 2 of the present invention, the FET as the power switching element is configured to be able to dissipate heat from both sides, and the low-loss electric power steering is A drive device can be provided.

The present invention is not limited to the electric power steering drive device according to the first and second embodiments described above, and the configurations of the first and second embodiments may be combined as appropriate without departing from the spirit of the present invention. It is possible to add a part of the configuration or to omit a part of the configuration.

The present invention can be used in the field of electric power steering devices, and in the field of vehicles such as automobiles using the electric power steering device.

100 electric power steering drive device, 200 integrated multilayer board, 21 control area, 22 heat sink, 221 extension part, 23 power area, 1 battery, 2 noise filter, 3 power relay part, 31, 32 power relay FET, 4 3-phase bridge circuit, 5 motor relay section, 5u, 5v, 5w motor relay FET, 6u, 6v, 6w smoothing capacitor, 7u, 7v, 7w shunt resistor, 8 control board, 9 electric motor, 91 stator, 92 Rotor, 31 and 32, power relay FET, 6a, first buffer member, 2a, second buffer member, 24, third buffer member, 4e heat dissipation sheet, 11 power connector, 12 vehicle side signal connector, 13 for torque sensor Connector, 14 Vehicle side signal, 15 Torque sensor, 20 Electronic control unit 101, metal casing, 102 resin case, 4b, L-shaped terminal, 84 rotation sensor, 81 microcomputer, 82 FET drive circuit, 83 current detection means, 100 electric power steering drive, 41u, 41v, 41w high potential side FET , 42u, 42v, 42w Low potential side FET, UL U phase output line, VL V phase output line, WL W phase output line, PL positive side input line, NL negative side output line, UT U phase winding terminal, VT V Phase winding terminal, WT W phase winding terminal

Claims

An electric motor that generates an auxiliary torque corresponding to a steering torque that a driver applies to a steering system of a vehicle, and a control unit that controls driving of the electric motor are provided, and the driver's steering is assisted by the auxiliary torque. An electric power steering drive device,
The electric motor includes a metal casing fixed to an end portion in the axial direction thereof,
The control unit is
A power conversion circuit that has a plurality of power switching elements, and converts DC power from a DC power source mounted in the vehicle into AC power based on the switching operation of the power switching elements and supplies the AC power to the electric motor;
A control unit for controlling the switching operation of the power switching element;
A multilayer board on which at least a part of members constituting the power conversion circuit and the control unit is mounted;
The multilayer substrate is
A heat sink,
A first region fixed to the first surface of the heat sink and at least mounted with the power switching element;
A second region that is fixed to a second surface having a front-back relationship with the first surface of the heat radiating plate and on which at least a part of members constituting the control unit is mounted. And
The heat sink is
An extending portion that is exposed from at least one of the first region and the second region and extends in a direction in which the surface of the heat sink extends;
The extension portion is fixed to the metal casing so that at least a part thereof directly contacts the metal casing.
An electric power steering drive device.
The first region and the second region each include a plurality of layers provided with wiring patterns,
The power switching element mounted in the first region is wired by the wiring pattern provided in the layer of the first region,
At least a part of members constituting the control unit mounted in the second region is wired by the wiring pattern provided in the layer of the second region,
The thickness dimension of the wiring pattern provided in at least one layer of the first region is different from the thickness dimension of the wiring pattern provided in at least one layer of the second region. Formed,
The electric power steering drive device according to claim 1.
The power switching element is placed on a surface layer of the plurality of layers in the first region,
The first region includes a heat transfer member disposed through the plurality of layers,
The heat transfer member is configured to transmit heat generated by the power switching element to the heat radiating plate.
The electric power steering drive device according to claim 2, wherein
The power switching element is configured such that a surface opposite to a surface facing the multilayer substrate is in contact with the metal casing.
The electric power steering driving device according to any one of claims 1 to 3, wherein the electric power steering driving device is provided.
The first region and the second region of the multilayer substrate are respectively
A plurality of layers having wiring patterns;
A prepreg disposed between the plurality of layers,
The prepreg in the first region has a thermal conductivity higher than the thermal conductivity of the prepreg in the second region;
The electric power steering drive device according to any one of claims 1 to 4, wherein the electric power steering drive device is provided.
An insulating cover that is fixed to the metal housing and covers at least the multilayer substrate;
The multilayer substrate is mounted with a smoothing capacitor and a noise filter of the power conversion circuit,
The cover is configured to cover the smoothing capacitor and the noise filter, and is in contact with the smoothing capacitor through a first buffer member, and is in contact with the noise filter through a second buffer member. Configured,
The extending portion of the multilayer substrate is exposed from both the first region and the second region and extends in a direction in which the surface of the heat sink extends.
The extension portion is inserted between the metal casing and the cover,
One surface of the extension part abuts on the cover via a third buffer member,
The other surface forming a front-back relationship with the one surface of the extension portion is configured to directly contact the metal casing,
The electric power steering drive device according to any one of claims 1 to 5, wherein
The reaction force against the compression of the first buffer member and the reaction force against the compression of the second buffer member are:
It is configured to be smaller than the reaction force against the compression of the third buffer member.
The electric power steering drive device according to claim 6.