JP2018061363A - Motor drive device, motor system and electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor drive device by which a thermal load to a switching element protection circuit is reduced to reduce costs.SOLUTION: A motor drive device is provided with: a first substrate the surface of which is oppositely arranged to a motor; a second substrate arranged on a rear surface side of the first substrate; a switching element arranged on the first substrate; and a switching element protection circuit, at least a part of which, including a capacitor, is arranged on the second substrate, and which is connected in parallel with the switching element. Thus, a thermal load to the capacitor of the switching element protection circuit is reduced, and accordingly, it becomes possible to use a general inexpensive capacitor.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a motor drive device including a switching element, a motor system using the same, and an electric power steering device.

A motor system in which a power converter (inverter) and an electric motor are combined together is known. For example, a motor system used for an electric power steering apparatus includes an electric motor that generates an auxiliary torque corresponding to a steering torque of a driver applied to a steering wheel of a vehicle, and a motor driving apparatus that drives the electric motor. The motor drive device includes a power conversion device configured with 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.
In the immediate vicinity of the power switching element, a snubber circuit for suppressing voltage surge, noise or both, and for suppressing resonance generated between the wiring inductance between the FET and the smoothing capacitor and the parasitic capacitance of the FET. In some cases, a switching element protection circuit having a capacitor, such as a filter circuit, is connected.
On the other hand, the electric motor in operation generates heat, and the components arranged in the vicinity of the electric motor become high temperature. Similarly, the capacitor of the switching element protection circuit has a high temperature, but a general film capacitor or the like has a problem that the heat resistance temperature is low and the required operating characteristics cannot be sufficiently exhibited.
In response to such a problem, Patent Document 1 discloses a technique in which a snubber circuit having a capacitor configured to be capable of high-temperature operation is connected in the vicinity of a power switching element.

JP 2009-219268 A

  However, in the technique disclosed in Patent Document 1, a capacitor capable of operating at high temperature is expensive, and thus there is a problem that the cost of the motor drive device is higher than when a general inexpensive capacitor is used.

  The present invention has been made in order to solve the above-described problems, and the thermal load on the switching element protection circuit is reduced, and a cheaper capacitor can be used. As a result, the motor can be reduced in cost. The object is to provide a drive device.

  The motor drive device of the present invention is arranged on the first substrate, the second substrate disposed on the back surface side of the first substrate, and the first substrate disposed on the first substrate. A switching element protection circuit that is disposed on the second substrate and connected in parallel to the switching element.

  By disposing at least a part of the switching element protection circuit including the capacitor on the second substrate disposed on the back surface side of the first substrate facing the motor, the switching element protection circuit is connected to the capacitor. The thermal load is reduced, so that a general inexpensive capacitor can be used. As a result, a thermal drive to the switching element protection circuit is small, and a motor drive device with a lower cost can be obtained.

It is a block diagram which shows the circuit structure of the motor system by Embodiment 1 of this invention. It is the figure which showed the connection position of the snubber circuit. It is a schematic sectional drawing which shows the apparatus structure of the motor system by Embodiment 1 of this invention. It is a schematic sectional drawing which shows the laminated constitution of the laminated substrate in the motor system by Embodiment 1 of this invention. FIG. 3 is a schematic layout diagram of through holes in a multilayer substrate in the motor system according to Embodiment 1 of the present invention. It is the figure which showed the comparative example of through-hole arrangement | positioning. It is a schematic sectional drawing of the laminated substrate in the motor system by Embodiment 2 of this invention. It is a schematic sectional drawing of the laminated substrate in the motor system by Embodiment 3 of this invention. FIG. 10 is a schematic layout diagram of through holes in a multilayer substrate in a motor system according to Embodiment 4 of the present invention. It is the figure which showed the structure of the electric power steering apparatus by Embodiment 5 of this invention.

Embodiment 1 FIG.
Hereinafter, the motor drive apparatus according to the first embodiment of the present invention will be described with reference to the drawings by taking an electric power steering apparatus as an example.
<Circuit configuration>
FIG. 1 is a block diagram showing a circuit configuration of the electric power steering apparatus. In FIG. 1, a motor system 100 includes an electric motor 9 and an electronic control unit 20 as a motor drive device. The motor system 100 is electrically connected to the battery 1 mounted on the vehicle via the power connector 11, and various on-vehicle sensors 14 such as a vehicle traveling speed signal are input from the vehicle side via the on-vehicle various sensor connectors 12. Then, a steering torque signal from the torque sensor 15 is input via the torque sensor connector 13. The torque sensor 15 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 shutting off 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, a switching element driving circuit 82, a current detecting 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.
Each arm is connected with an n-type MOSFET (Metal-Oxide-Semiconductor FIELD-EFFECT-Transistor) as a power switching element. High-potential side FETs 41u, 41v, 41w 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 lower arm and V-phase on the low potential side Low potential side FETs 42u, 42v, and 42w are connected to the 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 5 u is connected to the U-phase winding terminal UT of 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 of 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 of 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.

  FETs are switched 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 that suppresses the surge voltage at the time of switching or a filter circuit for suppressing resonance that occurs between the wiring inductance between the FET and the smoothing capacitor and the parasitic capacitance of the FET when the FET is switched is provided. The snubber circuit and the resonance suppression filter circuit may be provided simultaneously. Hereinafter, the case of the snubber circuit will be described.

  The first snubber circuit connection position will be described with reference to FIG. In the U phase, the drain terminal of the high potential side FET 41u and the high potential side of the snubber circuit 41us are connected, and the source terminal of the high potential side FET 41u and the low potential side of the snubber circuit 41us are connected. Similarly, the drain terminal of the low potential side FET 42u and the high potential side of the snubber circuit 42us are connected, and the source terminal of the low potential side FET 42u and the low potential side of the snubber circuit 42us are connected. The low potential side of the snubber circuit 42us may be connected to the negative input line NL. A snubber circuit is similarly connected to the V phase and the W phase.

The second snubber circuit connection position will be described with reference to FIG. In the U phase, the high potential side of the snubber circuit 6us is connected to the positive input line PL, and the low potential side of the snubber circuit 6us is connected to the negative input line NL. The same applies to the V phase and the W phase.
In FIG. 2, one snubber circuit is connected to each phase, but one snubber circuit may be provided for three phases of the U phase, the V phase, and the W phase. Connection position).

The snubber circuit is connected to a C snubber configured with a capacitor to suppress a surge voltage, or a CR snubber in which a capacitor and a resistor are connected in series to suppress high-frequency vibration. It is not limited.
Further, the first, second, and third snubber circuit connection positions may be used in combination. In addition, for example, the snubber circuit configuration and connection position can suppress surge voltage or noise suppression, such as connecting a C snubber to the second snubber circuit connection position and connecting a CR snubber to the first snubber circuit connection position. It is possible to combine with the application.

  The armature of the electric motor 9 connected to the three-phase bridge circuit 4 provided in the electronic control unit 20 of FIG. 1, 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 current flowing in the winding; a microcomputer 81; a switching element 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 microcomputer 81 and the switching element drive circuit 82 are mounted on the 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 switching element 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. Switching element drive circuit so that the power relay FETs 31 and 32 of the part 3 and the motor relay FETs 5u, 5v and 5w of the motor relay part 5 are all turned off and the connection between the three-phase bridge circuit 4 and the electric motor 9 is cut off. A command is given to 82.
The switching element driving 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 performs power switching. The high potential side FETs 41u, 41v, and 41w and the low potential side FETs 42u, 42v, and 42w as elements 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, respectively. A travel speed signal is input as one of the various sensors 14. Further, the motor current is detected by the current detecting 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 switching element drive circuit 82.

The switching element driving circuit 82 generates a PWM driving signal when the rotational direction command and current control amount of the power steering are input from the microcomputer 81, and the high potential side FETs 41u, 41v, 41w, which are power switching elements, A voltage is applied to the potential 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 switching element drive circuit 52.

  In FIG. 1, the negative electrodes 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 composed of only 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.

<Device configuration>
FIG. 3 is a schematic cross-sectional view showing a device configuration of the motor system for the electric power steering device according to Embodiment 1 of the present invention. The motor system 100 includes the block circuit configuration shown in FIG. 1 and is configured as shown in FIG. In FIG. 3, a metal casing 101 having a heat sink function is disposed at the axially opposite output side end portion of the electric motor 9 composed of a three-phase brushless motor, and the metal casing 101 has an axially upper portion. A multilayer substrate 200 is disposed, smoothing capacitors 6u, 6v, 6w and a noise filter 2 are disposed in an upper portion of the multilayer substrate 200 in the axial direction, and a resin case 102 is disposed above them.
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.

  The laminated substrate 200 includes a power substrate 23 (first substrate), a heat radiating member 22, and a control substrate 21 (second substrate) arranged in this order from the motor side, and is integrally combined with each other. The power switching elements 41u, 41v, 41w, 42u, 42v, and 42w are arranged on the power board 23, and the snubber circuits 41us, 41vs, 41ws, 42us, 42vs, and 42ws are arranged on the control board 21 at least partially including a capacitor. The power switching element and the snubber circuit are connected to each other through through holes 411 and 412 that penetrate the multilayer substrate 200.

  An end portion in the outer peripheral direction of the heat radiating member 22 includes an extending portion 221 that extends in a radial direction from end portions in the radial direction of the power board 23 and the control board 21, and the extending portion 221 of the heat radiating member 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 multilayer substrate 200 is transferred from the extended portion 221 of the heat dissipation member 22 to the metal casing 101.

The power substrate 23 is a multilayer substrate having a copper wiring having a large thickness exceeding 100 μm. On the other hand, the control board 21 is a multilayer board having a thin copper wiring of 100 μm or less. Therefore, the layer configuration of the control board 21 and the power board 23 is not the same. In addition, the numerical value of the thickness of these copper wiring is an example. Moreover, although the thickness of the copper wiring used is different, the thickness of each of the control board 21 and the power board 23 may be the same or different.
Usually, when substrates having different layer configurations and thicknesses, such as the control substrate 21 and the power substrate 23, are integrally formed, warpage of the substrate becomes a problem. With respect to such a problem, since the heat dissipation member 22 is inserted between the power board 23 and the control board 21 in the apparatus configuration of FIG. The heat radiating member 22 is formed of a copper plate having a thickness that is the same as or larger than that of the copper wiring provided on one layer of the multilayer substrate that constitutes the power substrate 23. The heat radiating member 22 also has an effect of shielding heat from the motor and heat from the power switching element from the switching element protection circuit.

  One of the terminals of the smoothing capacitors 6 u, 6 v and 6 w and the terminal of the noise filter 2 are connected to the power board 23 through the control board 21 and the heat dissipation member 22. A rotation sensor 84 constituted by a magnetic sensor is connected to the power board 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 board 23.

In the laminated substrate 200 configured as described above, the power substrate 23 and the control substrate 21 are individually manufactured, and then the power substrate 23 and the control substrate 21 are fixed to both surfaces of the heat dissipation member 22 via the prepreg. It is manufactured by making it. Thereafter, the control board 21 and the power board 23 are wired.
A through-through hole (not shown) connected only by the power board 23 does not appear on the surface layer of the control board 21 at one end thereof, so that the component mounting area of the control board 21 is increased and the size can be reduced. is there. In addition, a through-through hole (not shown) connected only by the control board 21 does not appear on the power board 23 at one end thereof, so that the component mounting area of the power board 23 is increased and the size can be reduced. is there. Furthermore, since the wiring of the control board 21 is composed only of a thin copper plate of 100 μm or less per layer, the thickness of the control board 21 can be reduced, and as a result, the diameter of the through hole that runs through the control board 21 can be reduced. There is also.

  The microcomputer 81 and the switching element driving circuit 82 are arranged on the surface layer of the control board 21. The microcomputer 81 and the switching element drive circuit 82 are connected by a through through hole in the control board 21. The high potential side FETs 41u, 41v, 41w and the low potential side FETs 42u, 42v, 42w as power switching elements are arranged on the surface layer of the power substrate 23. 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 switching element driving circuit 82 through through-holes penetrating each substrate.

<Connection of power switching element and snubber circuit>
FIG. 4 is a schematic cross-sectional view showing the configuration of the laminated substrate 200. The connection of a power switching element and a snubber circuit is demonstrated based on U phase using FIG.
A power switching element 41u is mounted on the surface of the power board 23 on the motor side. A snubber circuit 41us is mounted on the surface layer of the control board 21 which is the back side of the power switching element 41u. The power switching element 41u and the snubber circuit 41us are electrically connected to each other through through holes 411 and 412. The same applies to the power switching element 42 and the snubber circuit 42us.
The through holes 411 and 412 are circular and plated on the inside, and the portions that penetrate the heat radiating member 22 are perforated so that the through holes 411 and 412 do not contact the heat radiating member 22. Yes. Note that the type of the through hole is not limited to this, and it is sufficient that the power switching element and the snubber circuit can be electrically connected.
In FIG. 4, the entire snubber circuit is mounted on the control board 21, but in the case of a CR snubber in which a capacitor and a resistor are connected in series, only the capacitor is placed on the control board 21 and the resistor is placed on the power board 23. Also good.

Normally, the maximum allowable junction temperature of the power switching element is about 150 ° C., but a general film capacitor used for a snubber circuit has a lower upper limit of the operating temperature range than the maximum allowable junction temperature of the power switching element, Usually 125 ° C. or lower.
Therefore, conventionally, when a capacitor is mounted on the surface layer of the power board 23, an expensive capacitor made of a special material corresponding to a high temperature is used so as to withstand an atmospheric temperature that is increased by heat generated from the motor. The cost was high.
On the other hand, in the present invention, the control board 21 to which the snubber circuit 41us is connected is located from the motor side via the power board 23 and the heat dissipation member 22, so that the ambient temperature is lower than that of the power board 23. Therefore, the thermal load on the capacitor of the snubber circuit 41us can be reduced, and a cheaper capacitor having a lower upper limit value of the operating temperature range can be used for the snubber circuit 41us.
A film capacitor is mainly used as the capacitor of the snubber circuit 41us. However, the present invention is not limited to this, and any type of capacitor may be used as long as it can withstand a reduced thermal load.

In addition, the power switching element 41u itself generates heat during operation, but in the present invention, the snubber circuit 41us is arranged on the control board 21 provided on the back side of the power board 23 on which the power switching element 41u is arranged. Therefore, the influence of heat from the power switching element 41u on the snubber circuit 41us can also be suppressed.
Also, compared to the case where the power switching element and the snubber circuit are arranged on the same surface of the substrate, the effective wiring length is shortened, so that the wiring inductance and the wiring resistance are reduced, resulting in a reduction in noise. There is also an effect.

  Furthermore, since the wiring pattern of the control board 21 is thinner than the wiring pattern of the power board 23, the thickness of the resin of the prepreg for filling the unevenness of the wiring pattern can be reduced. Therefore, when the snubber circuit is arranged on the control board 21, there is an effect that cooling can be performed more efficiently than when the snubber circuit is arranged on the power board 23.

Further, a copper inlay PIN is provided immediately below the power switching elements 41u and 42u. The copper inlay PIN extends to the lowest layer of the power board, and can efficiently transfer heat generated by the power switching element to the heat dissipation member via the prepreg. The copper inlay PIN may also be used for electrical connection between a surface copper pattern and a plurality of layers.
Further, a thermal via TV as a heat conducting member may be embedded immediately below the arrangement portion of the snubber circuits 41us and 42us so that the heat generated by the snubber circuit is radiated to the heat radiating member 22.

  In the through holes 411 and 412 that connect the power switching element 41u and the snubber circuit 41us, the high potential side 411 and the low potential side 412 run in parallel. Since the magnetic field is canceled on the high potential side 411 and the low potential side 412 of the through hole by running in parallel, the wiring inductance can be reduced. The connection between the power switching element 42u and the snubber circuit 42us is the same.

FIG. 5 shows a top view of the power board 23. In FIG. 5, a pair of second through holes 426u and 427u that connect the gate terminal 423u and source terminal 422u of the power switching element 42u and the switching element driving circuit are a pair of second through holes 426u and 427u that connect the snubber circuit and the power switching element. It arrange | positions in the position which opposes through the power switching element from one through hole 424u, 425u. That is, a connection point between the power switching element of the pair of first through holes 424u and 425u and a connection point of the power switching element of the pair of second through holes 426u and 427u are connected via the power switching element 42u. Opposed to each other.
Since high-frequency current flows in the snubber circuit when the power switching element is switched, it is necessary to prevent the electromagnetic interference that the through-hole connecting the snubber circuit has on the through-hole between the gate and source. By disposing the hole and the second through hole at positions facing each other through the power switching element, it is possible to suppress electromagnetic interference from the through hole connecting the snubber circuit to the through hole between the gate and the source. .

  A comparative example is shown in FIG. In FIG. 6, a pair of second through holes (426u, 427u) connecting the gate terminal 423u and the source terminal 422u of the power switching element 42u and the switching element driving circuit, and one connecting the snubber circuit and the power switching element. A pair of first through holes (424 ua, 425 ua) are concentrated on one side of the power switching element. When concentrated on one side, the through hole connecting the snubber circuit and the power switching element causes electromagnetic interference in the through hole connecting the gate / source terminal and the switching element driving circuit, and gives noise to the power switching element 42u. In addition, it may cause malfunction.

<Assembly of equipment>
As an assembly procedure of the motor system 100, the first buffer member 6a is disposed in the portion 1021 where the smoothing capacitors 6u, 6v, 6w of the resin case 102 are disposed, and the portion 1022 where the noise filter 2 of the resin case 102 is disposed. The second buffer member 2a is arranged on the second side, and then the smoothing capacitors 6u, 6v, 6w and the noise filter 2 are arranged in predetermined portions 1021, 1022 of the resin case 102, and the smoothing capacitors 6u, 6v, 6w are arranged. 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 a connection 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.
Prior to placing the multilayer substrate 200 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 radiating member 22 and the metal casing 101 as the 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 multilayer substrate 200, and the L-shaped terminal 4b soldered in advance to the power substrate 23 of the multilayer substrate 200. Connect to. This connecting portion may be welded, soldered, screwed, or press fit. The through-holes provided in the multilayer substrate 200 are provided through the control board 21, the heat dissipation member 22, and the power board 23, and the through-through holes and the power board provided only in the control board described above. This is a separate body from the through-holes provided only in the case.
In the first embodiment, the smoothing capacitors 6u, 6v, 6w and the terminals of the noise filter 2 are connected to the multilayer substrate 200 to which the L-shaped terminal 4b is soldered in advance, but directly without providing the L-shaped terminal 4b. You may solder to the land of the 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 member 22 of the 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.

  As described above, according to the first embodiment, the snubber circuit is arranged on the control board provided on the back side of the power board (motor side) on which the power switching element is arranged. The thermal load on the capacitor is reduced, and a general inexpensive capacitor can be used. As a result, it is possible to obtain a motor drive device that has a low thermal load on the snubber circuit and is low in cost.

Although the snubber circuit has been described as an example, the present invention is not limited to this, and the same applies to a switching element protection circuit arranged in the immediate vicinity of the power switching element, such as a resonance suppression filter circuit. Can do.
Moreover, although the electric power steering apparatus has been described as an example, the present invention is not limited to this, and the present invention can be similarly applied to any motor system in which a motor driving apparatus including a power conversion apparatus and a motor are integrally combined.

Embodiment 2. FIG.
A motor drive apparatus according to Embodiment 2 of the present invention will be described. FIG. 7 is a diagram showing a configuration of a motor drive device according to Embodiment 2 of the present invention. The second embodiment is the same as the first embodiment except that there is no heat dissipation member.
Even if there is no heat dissipation member, the snubber circuit is arranged on the control board provided on the back side of the power board (motor side) where the power switching element is arranged, so that the effect of heat from the motor on the snubber circuit Can be suppressed.

Embodiment 3 FIG.
A motor drive apparatus according to Embodiment 3 of the present invention will be described. FIG. 8 is a diagram showing a configuration of a motor drive device according to Embodiment 3 of the present invention. The circuit configuration of the motor driving apparatus according to the third embodiment of the invention is the same as that shown in FIG. In FIG. 8, the same reference numerals are given to the same or equivalent components as those shown in FIG. 4. Here, the description will be focused on the portion related to the third embodiment.
In the first embodiment described above, the snubber circuit is mounted on the surface layer of the control board 21, but in the third embodiment, the snubber circuits 41us and 42us are embedded in the control board 21a.
By embedding the snubber circuit in the control board 21a, the mounting area of the surface layer of the control board 21a is increased, so that the board can be downsized, and as a result, the motor system can be downsized. Further, since the through-hole length is shorter than the case where it is arranged on the surface layer, the wiring inductance and the wiring resistance can be reduced. Also, by embedding the components in the substrate, the components are fixed with resin, and there is an effect that the strength against vibration is increased.

Embodiment 4 FIG.
A motor drive apparatus according to Embodiment 4 of the present invention will be described. FIG. 9 is a diagram showing the positional relationship between a through hole that connects a snubber circuit and a power switching element, a through hole that connects a gate-source terminal, and a switching element drive circuit according to Embodiment 4 of the present invention. is there. The circuit configuration of the motor system according to the fourth embodiment of the invention is the same as that shown in FIG. In FIG. 9, the same or similar components as those shown in FIG. 5 are denoted by the same reference numerals. Here, the description will be focused on the portion related to the fourth embodiment.
In the fourth embodiment, the gate resistor RG42 is mounted on the surface layer of the power substrate closest to the gate terminal 423u of the power switching element 42u. By connecting the gate resistor RG42 in the immediate vicinity of the power switching element 42u, the parasitic resistance (not shown) of the gate resistor RG42 and the power switching element plays the role of a low-pass filter. Since the superimposed high-frequency noise component is removed, the influence of electromagnetic interference on the gate voltage of the power switching element 42u can be suppressed. As a result, malfunction of the power switching element due to the influence of noise between the gate and the source of the power switching element can be prevented.

Embodiment 5. FIG.
Embodiment 5 of the present invention will be described with reference to FIG. In the fifth embodiment, the motor drive device 20 of the first embodiment is applied to an electric power steering device.
The electric power steering apparatus of FIG. 10 includes a motor system 100 including the motor drive apparatus 20 and the motor 9 of the first embodiment. The motor drive device 20 drives the motor 9 according to signals from the torque sensor 15 that detects the torque of the driver's steering wheel operation and various in-vehicle sensors, and applies auxiliary torque to the steering mechanism of the vehicle.
By using the motor drive device of the first embodiment, an electric power steering device with a low thermal load on the switching element protection circuit and a low cost can be obtained.
FIG. 10 shows the column assist type electric power steering apparatus, but the present invention is not limited to this, and the present invention can be applied to any of the pinion assist type and rack assist type electric power steering apparatuses.

  While the embodiments have been described above, the present invention is not limited to the above-described embodiments, and can be implemented in various forms without departing from the spirit of the invention.

100 motor system,
20 electronic control unit,
200 laminated substrate,
21 control board,
22 heat dissipation member,
221 extension part,
23 Power board,
1 battery,
2 noise filter,
3 Power relay section,
31, 32 FET for power relay,
4 3-phase bridge circuit,
41u, 41v, 41w high potential side FET,
41us, 41vs, 41ws snubber circuit,
42u, 42v, 42w low potential side FET,
42us, 42vs, 42ws snubber circuit,
4b L-shaped terminal,
5 Motor relay part,
5u, 5v, 5w Motor relay FET,
6u, 6v, 6w smoothing capacitor,
6us snubber circuit 7u, 7v, 7w shunt resistor,
8 control unit,
81 microcomputer,
82 switching element drive circuit,
83 current detection means,
84 Rotation sensor,
9 Electric motor,
91 Stator,
92 rotors,
6a 1st buffer member,
2a second buffer member,
24 3rd buffer member,
11 Power connector,
12 In-vehicle sensor connectors,
13 Torque sensor connector,
14 Vehicle-mounted sensors,
15 torque sensor,
101 metal housing,
102 resin case,
UL U-phase output line,
VL V-phase output line,
WL W phase output line,
PL positive side input line,
NL Negative output line,
UT U-phase winding terminal,
VT V phase winding terminal,
WT W phase winding terminal,
TV thermal via,
PIN copper inlay

Claims (13)

A first substrate having a surface disposed facing the motor; a second substrate disposed on the back side of the first substrate; a switching element disposed on the first substrate; and a capacitor. A motor drive apparatus comprising: a switching element protection circuit disposed at least in part on the second substrate and connected in parallel to the switching element. The switching element and the switching element protection circuit are connected through a set of first through holes.
The motor driving apparatus according to claim 1, wherein The set of first through holes are arranged in parallel,
The motor driving apparatus according to claim 1 or 2, wherein the motor driving apparatus is provided. The switching element protection circuit is a snubber circuit or a resonance suppression filter circuit.
The motor driving device according to any one of claims 1 to 3, wherein the motor driving device is provided. Between the first substrate and the second substrate, a heat dissipation member made of a material having higher thermal conductivity than the first substrate and the second substrate,
The motor drive device according to any one of claims 1 to 4, wherein the motor drive device is provided. A metal housing disposed around the first substrate, the second substrate, and the heat dissipation member; and an end portion of the heat dissipation member from an end portion of the first substrate and the second substrate. Also extends in the outer circumferential direction and contacts the metal casing,
The motor driving apparatus according to claim 5, wherein The switching element protection circuit is embedded in a second substrate in a region where at least a part including the capacitor is disposed, and is made of a material having a higher thermal conductivity than the second substrate, and the heat of the capacitor A heat conducting member that conducts heat to the heat radiating member,
The motor drive device according to claim 5 or 6, wherein the motor drive device is provided. The first substrate and the heat dissipation member, and the second substrate and the heat dissipation member are fixed via a prepreg, and the thickness of the prepreg between the second substrate and the heat dissipation member is , Smaller than the thickness of the prepreg between the first substrate and the heat dissipation member,
The motor driving apparatus according to claim 5, wherein the motor driving apparatus is provided. At least a part of the switching element protection circuit including the capacitor is embedded in the second substrate.
The motor drive device according to claim 1, wherein the motor drive device is a motor drive device. A switching element driving circuit disposed on the second substrate;
A set of second through holes connecting the switching element drive circuit and the gate terminal and source terminal of the switching element;
A connection point of the set of first through holes with the switching element and a connection point of the set of second through holes with the switching element are arranged to face each other through the switching element.
The motor drive device according to claim 1, wherein the motor drive device is provided. A switching element driving circuit disposed on the second substrate;
A set of second through holes connecting the switching element drive circuit and the gate terminal and source terminal of the switching element;
A gate resistor is connected between the gate terminal of the switching element and the second through hole,
The motor drive device according to claim 1, wherein the motor drive device is provided. A motor drive device according to any one of claims 1 to 11, a motor disposed adjacent to the motor drive device and driven by the motor drive device,
Motor system equipped with. An electric power steering apparatus comprising the motor system according to claim 12 and applying an auxiliary torque to a steering mechanism of a vehicle by the motor system.

Images