Circuit board for driving motor, motor and pump device

Abstract

To suppress increase of noise due to division of a ground pattern.SOLUTION: A circuit board for driving a motor of a pump device is a multilayer board for mounting a motor driving circuit including a power system circuit 170 including an inverter circuit, and a signal system circuit 160 for supplying a control signal to the inverter circuit. In the multilayer board, a ground patter 100 is formed on each layer, and the power system circuit, the signal system circuit, and a noise countermeasure circuit 180 having a capacitor are formed on a first layer 111. A fourth layer circuit 114C including the power system circuit, a fourth conducting layer G4 which is the ground pattern, and a common line 14 for connecting a neutral point of a three-phase coil and the noise countermeasure circuit, are formed on a fourth layer 114. The common line is arranged in a boundary between the fourth layer circuit and the fourth conducting layer, and extends to a region overlapping on the noise countermeasure circuit along the shape of the fourth conducting layer.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a motor drive circuit board, a motor, and a pump device. [Background technology]

[0002] In recent years, EMC (Electromagnetic Compatibility) has become a requirement for circuit boards that mount motor drive circuits. EMC refers to the compatibility of EMI (Electromagnetic Interference, the phenomenon of electromagnetic energy being emitted) and EMS (Electromagnetic Susceptibility, the ability to operate without performance degradation or malfunction due to external electromagnetic energy).

[0003] A substrate on which a motor drive circuit is mounted is required to mount circuits at a high density. For this reason, a multilayer substrate is used in which multiple layers, each having a wiring pattern that constitutes the circuit, are stacked with an insulating layer interposed between them. Patent Document 1 describes this type of multilayer substrate.

[0004] Patent Document 2 describes a drive circuit for a motor used in a pump device. In the drive circuit of Patent Document 2, as a noise countermeasure, a common line connected to the neutral point of a three-phase coil is connected to ground (reference potential) via a capacitor. This smooths the voltage at the neutral point, thereby suppressing noise generated by the motor drive circuit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-183540 [Patent Document 2] Japanese Patent Publication No. 2022-141993 Summary of the Invention [Problem to be solved by the invention]

[0006] As an EMC measure for motor drive circuit boards, in multilayer boards, a ground pattern is formed around the circuit patterns on each layer where the circuit patterns are formed. For example, a ground pattern is formed around relatively high-voltage circuits (hereinafter referred to as power circuits) including inverter circuits that output drive current and circuits that connect three-phase coils. This suppresses noise radiation.

[0007] However, depending on the layout of the circuit patterns, routing the wiring connected to the power circuitry along the shortest path can sometimes disrupt the ground pattern formed around the power circuitry, raising concerns about increased noise.

[0008] For example, when a common wire connected to the neutral point of a three-phase coil is routed via the shortest route to a capacitor on the power supply side as a noise countermeasure, the wiring pattern of the common wire routed via the shortest route may divide the ground pattern, raising concerns about increased noise.

[0009] In view of the above problems, an object of the present invention is to suppress an increase in noise due to the division of the ground pattern when mounting a motor drive circuit on a multilayer board. [Means for solving the problem]

[0010] In order to solve the above problems, one aspect of the circuit board for a motor drive circuit according to the present invention is a circuit board for a motor drive circuit, comprising: a power circuit including an inverter circuit for applying a drive voltage to three-phase coils; a signal system circuit having control elements that supply control signals to a signal path, the signal system circuit having a control element that supplies control signals to a signal path, and the signal system circuit having a control element that supplies control signals to a signal path; and a motor drive circuit provided on a multilayer substrate, the multilayer substrate includes four layers stacked in the order of a first layer, a second layer, a third layer, and a fourth layer, each having a ground pattern formed on it, the first layer having a first-layer circuit including the power system circuit and the signal system circuit and a noise suppression circuit having a capacitor, when any of the second layer, the third layer, and the fourth layer is designated as an Nth layer, the Nth layer having an Nth-layer circuit including the power system circuit, an Nth conductive layer which is the ground pattern, and a common wire connecting the neutral points of the three-phase coils and the noise suppression circuit, the common wire being located at the boundary between the Nth-layer circuit and the Nth conductive layer, bending along the shape of the Nth conductive layer, and extending to an area where it overlaps with the noise suppression circuit.

[0011] Next, one aspect of the motor according to the present invention is characterized by having the motor drive circuit board described above and the three-phase coils to which a drive voltage is applied from the inverter circuit.

[0012] Next, one aspect of the pump device according to the present invention is characterized by including the motor described above and an impeller that is rotationally driven by the motor. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view of a pump device including a motor. [Figure 2] FIG. 2 is a cross-sectional view of a pump device including a motor. [Figure 3] FIG. 3 is a plan view of one side and the other side of the motor drive circuit board. [Figure 4] FIG. 4 is a circuit diagram of a motor drive circuit mounted on a motor drive circuit board. [Figure 5] FIG. 5 is an explanatory diagram showing the configuration of each layer of the multilayer substrate. [Figure 6] FIG. 6 is an explanatory diagram showing the arrangement of the common lines. [Figure 7]FIG. 7 is a diagram illustrating the noise reduction effect achieved by the arrangement of the common lines. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, with reference to the drawings, an embodiment of the motor drive circuit board 19, the motor 2, and the pump device 1 will be described. In the following description, the direction along the rotation axis L of the motor 2 is referred to as the axial direction, one side of the axial direction is referred to as L1, and the other side of the axial direction is referred to as L2.

[0015] (Pumping equipment) Fig. 1 is a perspective view of a pump device 1 equipped with a motor 2. Fig. 2 is a cross-sectional view of the pump device 1 equipped with the motor 2. As shown in Figs. 1 and 2, the pump device 1 includes the motor 2, an impeller 3 that is rotationally driven by the motor 2, and a case 4 that covers the motor 2 from one axial side L1. The motor 2 includes a rotor 5, a stator 7 that surrounds the outer periphery of the rotor 5, a resin sealing member 8 that covers the stator 7, a cover 9 that is fixed to the resin sealing member 8 from the other axial side L2, and a motor drive circuit board 19.

[0016] The impeller 3 is disposed in a pump chamber 20 defined by the resin sealing member 8 of the motor 2 and the case 4. The impeller 3 and rotor 5 rotate together about the rotation axis L. The stator 7 includes a stator core 70 and a coil 6 wound around the stator core 70 with an insulator 71 interposed between them. The motor 2 is a three-phase motor and includes three-phase coils 6. A motor drive circuit board 19 is disposed between the bottom of the resin sealing member 8 and the cover 9.

[0017] (Motor drive circuit board) 3 is a plan view of one surface S1 and the other surface S2 of the motor drive circuit board 19. One surface S1 is a board surface facing one side L1 in the axial direction and facing the bottom of the resin sealing member 8. The other surface S2 is a board surface facing the other side L2 in the axial direction and facing the cover 9. The motor drive circuit board 19 is a double-sided board, and electronic elements are mounted on one surface S1 and the other surface S2. 3, the outer periphery of motor drive circuit board 19 is provided with linearly cut-out portions 196 and three protrusions 197. Motor drive circuit board 19 is fixed to resin sealing member 8 via three protrusions 197.

[0018] A plurality of connector terminal holes 195 are provided in an area along the straight portion 196 on the outer periphery of the motor drive circuit board 19. As shown in FIG. 1, the resin sealing member 8 of the motor 2 is provided with a connector housing 80 that protrudes toward the outer periphery. Connector terminals held in the connector housing 80 protrude from the bottom of the resin sealing member 8 toward the cover 9 and fit into the connector terminal holes 195 of the motor drive circuit board 19. The motor drive circuit board 19 is electrically connected to external devices and a power source via the connector terminals soldered to the connector terminal holes 195.

[0019] A plurality of terminal holes 190U, 190V, 190W, and 190C are provided in an area on the radially opposite side of the straight portion 196 on the outer circumferential edge of the motor drive circuit board 19. As shown in Fig. 2, the tips of the plurality of winding terminals 72 held at the bottom of the resin sealing member 8 on the other axial side L2 are fitted into and soldered to the terminal holes 190U, 190V, 190W, and 190C of the motor drive circuit board 19. The three-phase coils 6 are electrically connected to the motor drive circuit board 19 via the winding terminals 72.

[0020] Fig. 4 is a circuit diagram of motor drive circuit 10 mounted on motor drive circuit board 19. As shown in Fig. 4, motor drive circuit 10 is electrically connected to a constant voltage terminal 751 to which a rated drive voltage of 12 V is applied, a first signal terminal 752 to which a PWM signal is input, a second signal terminal 753 that outputs a rotation speed signal corresponding to the rotation speed of motor 2, and a ground terminal 754 to which ground potential is applied.

[0021] The connector terminals soldered to connector terminal holes 195 of motor drive circuit board 19 include a constant voltage terminal 751, a first signal terminal 752, a second signal terminal 753, and a ground terminal 754. As shown in FIG. 3 , connector terminal holes 195 include a first terminal hole 191, a second terminal hole 192, a third terminal hole 193, and a fourth terminal hole 194. First terminal hole 191, into which constant voltage terminal 751 fits, and fourth terminal hole 194, into which ground terminal 754 fits, are located at both ends of straight portion 196. Second terminal hole 192, into which first signal terminal 752 fits, and third terminal hole 193, into which second signal terminal 753 fits, are located between first terminal hole 191 and fourth terminal hole 194.

[0022] As shown in FIG. 4, the three-phase coil 6 includes a U-phase coil 61, a V-phase coil 62, and a W-phase coil 63. As shown in FIG. 3, the motor drive circuit board 19 is provided with a terminal hole 190U for connection to the U-phase coil 61, a terminal hole 190V for connection to the V-phase coil 62, a terminal hole 190W for connection to the W-phase coil 63, and a terminal hole 190C for a common terminal. One ends of the windings of the U-phase coil 61, the V-phase coil 62, and the W-phase coil 63 are electrically connected to winding terminals 72 soldered to terminal holes 190U, 190V, and 190W, respectively. The plurality of winding terminals 72 includes a common terminal. The other ends of the windings of the U-phase coil 61, the V-phase coil 62, and the W-phase coil 63 are electrically connected to the common terminal.

[0023] 4, the motor drive circuit 10 includes a motor control unit 11 that controls the rotation of the motor 2 using a PWM signal, an inverter circuit 12 that applies a drive voltage to the three-phase coils 6 based on an output signal from the motor control unit 11, and a drive voltage line 13 that applies the drive voltage to the motor control unit 11 and the inverter circuit 12. A drive voltage of rated 12 V is applied to the drive voltage line 13 via a constant voltage terminal 751.

[0024] The motor control unit 11 outputs an output signal for controlling the inverter circuit 12 based on a PWM signal input from an external device. The external device outputs a PWM signal to the motor control unit 11 based on the rotation speed signal to make the motor 2 rotate at a desired rotation speed.

[0025] The three-phase coils 6 are connected by a star connection. As shown in Fig. 4, the motor drive circuit 10 includes a common wire 14 connected to the neutral point 65 of the three-phase coils 6, and a core connection wire 73 electrically connected to the stator core 70. The core connection wire 73 is electrically connected via the common wire 14 to a ground pattern 100 provided on the motor drive circuit board 19.

[0026] The motor drive circuit 10 includes a control signal line 15 to which a PWM signal is input from an external device via a first signal terminal 752, an FG output line 16 to which a rotation speed signal corresponding to the rotation speed of the motor 2 is output to an external device via a second signal terminal 753, and a ground line 17 connected to a ground terminal 754.

[0027] As shown in Fig. 3, a motor control unit 11 consisting of a control element such as an IC chip, and electronic elements for noise suppression are mounted on one surface S1 of the motor drive circuit board 19. The electronic elements for noise suppression include an inductor 18 and a plurality of capacitors (not shown in Fig. 3). The inductor 18 is, for example, a choke coil. Switching elements Q1 to Q6 are mounted on the other surface S2 of the motor drive circuit board 19.

[0028] As shown in Fig. 4, the inverter circuit 12 includes switching elements Q1 and Q2 for the U-phase coil, switching elements Q3 and Q4 for the V-phase coil, and switching elements Q5 and Q6 for the W-phase coil. The switching elements Q1 to Q6 are, for example, MOS-type FETs. The drains of the switching elements Q1, Q3, and Q5 are connected to the drive voltage line 13. The sources of the switching elements Q2, Q4, and Q6 are connected to the ground pattern 100 via a shunt resistor Rs. Both ends of the shunt resistor Rs are connected to the motor control unit 11 via output lines 121 and 122. Resistors R33 and R34 are electrically connected in series to the output lines 121 and 122.

[0029] A capacitor 51 is connected between the source of switching element Q1 and the drain of switching element Q2. A capacitor 52 is connected between the source of switching element Q3 and the drain of switching element Q4. A capacitor 53 is connected between the source of switching element Q5 and the drain of switching element Q6. Capacitors 51 to 53 serve as charging and discharging capacitors for the bootstrap circuit. Bootstrap diodes D31 to D33 are connected between capacitors 51 to 53 and motor control unit 11, respectively. Diodes D31 to D33 are connected to motor control unit 11 via resistor R31.

[0030] Resistors R11 to R16 are connected between the gate and source of each of the switching elements Q1 to Q6. Resistors R21 to R26 are connected between the gate of each of the switching elements Q1 to Q6 and the motor control unit 11. Filters 41 to 46 are connected between the drain and source of each of the switching elements Q1 to Q6. The filters 41 to 46 are each made up of a resistor and a capacitor connected in series.

[0031] Based on the output signal output from the motor control unit 11, the inverter circuit 12 converts the drive voltage supplied from the drive voltage line 13 into a three-phase AC drive voltage by switching the switching elements Q1 to Q6, and supplies it to the three-phase coils 6.

[0032] As shown in FIG. 4, the motor drive circuit 10 includes, as noise suppression electronic elements, an inductor 18, a first capacitor 21, a second capacitor 22, a third capacitor 23, a fourth capacitor 24, a fifth capacitor 25, a sixth capacitor 26, and a seventh capacitor 27. , an eighth capacitor 28 and a ferrite bead 29.

[0033] The inductor 18 is connected in series to the drive voltage line 13. On the input side of the inductor 18, a second capacitor 22 and a third capacitor 23 are electrically connected in series between the drive voltage line 13 and the ground pattern 100. The common line 14 is electrically connected between the second capacitor 22 and the third capacitor 23. A ground terminal 754 is electrically connected between the third capacitor 23 and the ground pattern 100.

[0034] As a result, the neutral point 65 electrically connected to the common line 14 is clamped by the second capacitor 22 and the third capacitor 23, so that even if a voltage of relatively large amplitude occurs at the neutral point, the voltage at the neutral point 65 is smoothed. This makes it possible to suppress noise generated in the motor 2. Furthermore, as described above, the core connection line 73 is electrically connected to the ground pattern 100 via the common line 14, so that noise generated in the stator core 70 can be suppressed.

[0035] On the output side of the inductor 18, a diode 31 is electrically connected between the drive voltage line 13 and the ground pattern 100. The diode 31 protects the elements in the motor drive circuit 10 from surge voltages. Furthermore, on the output side of the diode 31, a first capacitor 21, a seventh capacitor 27, and an eighth capacitor 28 are electrically connected between the drive voltage line 13 and the ground pattern 100. This allows the drive voltage supplied from the drive voltage line 13 to be smoothed.

[0036] 4, the drive voltage line 13 branches into a first line 131 and a second line 132, and supplies power to the motor control unit 11 via the first line 131 and the second line 132. The second line 132 is electrically connected to the motor control unit 11 via a resistor R32. The diode 31, the first capacitor 21, and the seventh capacitor 27 are electrically connected to the drive voltage line 13 on the input side of the branch of the first line 131 and the second line 132. The eighth capacitor 28 is electrically connected to the first line 131.

[0037] A ferrite bead 29, a fourth capacitor 24, a sixth capacitor 26, and a resistor R3 are connected to the control signal line 15. The fourth capacitor 24 is electrically connected between the control signal line 15 and the ground pattern 100. This allows the PWM signal transmitted through the control signal line 15 to be leveled, thereby reducing noise generated in the control signal line 15.

[0038] The ferrite bead 29 is electrically connected in series to the control signal line 15 at a portion of the control signal line 15 closer to the output side than the fourth capacitor 24. The sixth capacitor 26 is electrically connected between the ferrite bead 29 and the ground pattern 100 at a portion of the control signal line 15 closer to the output side. This makes it possible to further reduce noise generated in the control signal line 15.

[0039] The resistor R3 is electrically connected in series to the control signal line 15 at a portion of the control signal line 15 closer to the output side than the sixth capacitor 26. A third line 151, which is connected to the first line 131, is connected to the control signal line 15. The third line 151 is electrically connected to the control signal line 15 between the ferrite bead 29 and the resistor R3. A resistor R2 is electrically connected in series to the third line 151.

[0040] A fifth capacitor 25, a resistor R1, and a NOT gate Q7 are connected to the FG output line 16. The fifth capacitor 25 is electrically connected between the FG output line 16 and the ground pattern 100. This makes it possible to level the rotation speed signal generated in the FG output line 16. Therefore, the noise generated in the FG output line 16 can be reduced.

[0041] The resistor R1 is electrically connected in series to the FG output line 16 at a portion of the FG output line 16 closer to the input side than the fifth capacitor 25. The NOT gate Q7 is electrically connected in series to the FG output line 16 at a portion of the FG output line 16 closer to the input side than the resistor R1.

[0042] (Multilayer board) The motor drive circuit board 19 is a multilayer board 110 in which multiple layers are stacked with insulating layers interposed between them. FIG. 5 is an explanatory diagram showing the configuration of each layer of the multilayer board 110. In the multilayer board 110, multiple insulating layers stacked on the board body form multiple layers on which conductive layers such as wiring and electrodes are arranged. The conductive layers formed on different layers are electrically connected by contact holes that penetrate the insulating layers. The conductive layers such as wiring and electrodes are made of copper layers.

[0043] As shown in Figure 4, in this specification, in motor drive circuit 10, a relatively low-voltage circuit including motor control unit 11 and circuits for inputting and outputting control signals is referred to as signal system circuit 160. Furthermore, a relatively high-voltage circuit including wiring for connecting inverter circuit 12 and three-phase coils 6 is referred to as power system circuit 170. Furthermore, a circuit in which noise suppression electronic elements such as capacitors are electrically connected to drive voltage line 13 is referred to as noise suppression circuit 180. As described above, common line 14 is routed to connect neutral point 65 of three-phase coils 6 and noise suppression circuit 180, and functions as noise suppression wiring.

[0044] The ground pattern 100 provided on the multilayer substrate 110 is a common ground pattern that is electrically connected to both the signal circuitry 160 and the power circuitry 170. The common ground pattern functions both as a ground pattern for the signal circuitry 160 and as a ground pattern for the power circuitry 170.

[0045] Multilayer substrate 110 includes six layers, namely, first layer 111, second layer 112, third layer 113, fourth layer 114, fifth layer 115, and sixth layer 116, as shown in Fig. 5. Lands (not shown) on which electrical elements are mounted are formed on first layer 111, which is the uppermost layer. Conductive layers that function as ground pattern 100 are formed on all layers of multilayer substrate 110.

[0046] The ground pattern 100 includes a first conductive layer G1 formed on the first layer 111, a second conductive layer G2 formed on the second layer 112, a third conductive layer G3 formed on the third layer 113, a fourth conductive layer G4 formed on the fourth layer 114, a fifth conductive layer G5 formed on the fifth layer 115, and a sixth conductive layer G6 formed on the sixth layer 116. In FIG. 5, the areas where these conductive layers are formed are shown as hatched areas.

[0047] As shown in FIG. 5, the motor drive circuit 10 includes a first layer circuit 111C provided on the first layer 111, a second layer circuit 112C provided on the second layer, a fourth layer circuit 114C provided on the fourth layer, and a sixth layer circuit 116C provided on the sixth layer.

[0048] 5, the area in each layer where the signal circuit 160 is formed is shown as an area surrounded by a two-dot chain line, the area in each layer where the power circuit 170 is formed is shown as an area surrounded by a one-dot chain line, and the area in the first layer 111 where the noise suppression circuit 180 is formed is shown as a hatched area.

[0049] The shapes of the circuits and conductive layers on each layer shown in Figure 5 indicate the approximate layout areas of the electrical elements, wiring, conductive layers, etc. that make up the circuit, and do not include fine wiring, contact holes, etc. Conductive layers are not formed around contact holes or wiring.

[0050] As shown in FIG. 5, the first layer circuit 111C includes a signal circuit 160 and a power circuit 170. The signal circuit 160 is disposed in the region between terminal hole 190C, to which the common terminal is connected, and fourth terminal hole 194, to which ground terminal 754 is connected. The central portion of the signal circuit 160 overlaps with the motor control unit 11. The power circuit 170 is disposed in a region extending from the center of the board to the positions of terminal holes 190U, 190V, and 190W, to which three coils 6 are connected. A noise suppression circuit 180 is disposed along the outer periphery of the board in the range from the first terminal hole 191, to which the constant voltage terminal 751 is connected, to the inductor 18.

[0051] The first conductive layer G1 is arranged in the area surrounding the power circuit 170 and the signal circuit 160 along the outer periphery of the substrate, as well as in the area of the fourth terminal hole 194 to which the ground terminal 754 is connected, and in the area between the noise countermeasure circuit 180 and the signal circuit 160.

[0052] The second layer circuit 112C includes a power circuit 170. The power circuit 170 of the second layer circuit 112C overlaps with the power circuit 170 of the first layer circuit 111C, and is arranged in an area smaller than the power circuit 170 of the first layer circuit 111C. The second conductive layer G2 is arranged in a range of the entire substrate of the second layer 112, excluding the area where the power circuit 170 is arranged and the area overlapping with the inductor 18 and the noise countermeasure circuit 180.

[0053] The ground pattern 100 is not formed in any portion of the multilayer substrate 110 that overlaps with the inductor 181. Furthermore, the ground pattern 100 is not formed in an area that overlaps with the noise countermeasure circuit 180. As shown in Fig. 5, each of the second conductive layer G2, the third conductive layer G3, the fourth conductive layer G4, the fifth conductive layer G5, and the sixth conductive layer G6 has a hollowed-out shape in the portions that overlap with the inductor 181 and the noise countermeasure circuit 180.

[0054] On the third layer 113, a third conductive layer G3 is formed over the entire substrate. Similarly, on the fifth layer 115, a fifth conductive layer G5 is formed over the entire substrate. As described above, the third conductive layer G3 and the fifth conductive layer G5 have hollowed-out shapes in the portions that overlap with the inductor 18 and the noise suppression circuit 180.

[0055] The fourth layer circuit 114C includes a power circuit 170. The power circuit 170 of the fourth layer circuit 114 is arranged in an area overlapping with the power circuit 170 of the first layer circuit 111C. The fourth conductive layer G4 is arranged in a range of the entire substrate of the fourth layer 114 excluding the area where the power circuit 170 is arranged and the area overlapping with the inductor 18 and the noise suppression circuit 180. The fourth layer 114 has a common line 14 arranged thereon, which electrically connects the noise suppression circuit 180 and the neutral point 65 of the three-phase coil 6.

[0056] The sixth layer circuit 116C includes a signal circuit 160 and a power circuit 170. The signal circuit 160 overlaps with the signal circuit 160 of the first layer circuit 111C, and is arranged in an area smaller than the signal circuit 160 of the first layer circuit 111C. Like the first layer circuit 111C, the power circuit 170 is arranged in an area extending from the center of the substrate to the positions of terminal holes 190U, 190V, and 190W that are connected to the three coils 6.

[0057] The sixth conductive layer G6 is disposed along the outer periphery of the substrate so as to surround the power circuit 170, and extends into the region between the center of the substrate and the second terminal hole 192, the third terminal hole 193, and the fourth terminal hole.

[0058] 5, the ground pattern 100 of the multilayer substrate 110 extends continuously along the outer periphery of the substrate where the terminal holes 190U, 190V, 190W, and 190C are provided on each of the first layer 111, second layer 112, fourth layer 114, and sixth layer 116 where the power circuit 170 is provided, and surrounds the outer periphery of the power circuit 170. The ground pattern in this portion The power circuit 170 is connected to the ground patterns 100 on the upper and lower layers by through holes (not shown) provided on the outer periphery of the board, thereby reducing noise radiation from the power circuit 170 to the outside of the board.

[0059] (Common line placement) FIG. 6 is an explanatory diagram showing the arrangement of the common line 14. The upper diagram in FIG. 6 shows the configuration of the fourth layer 114 of this embodiment, and the lower diagram in FIG. 6 shows the configuration of the fourth layer 114A of the comparative example. As shown in FIGS. 5 and 6, on the fourth layer 114 of this embodiment, the common line 14 extends from near the terminal hole 190C to which the common terminal is connected to near the first terminal hole 191 to which an external power supply is connected. One end of the common line 14 extends from near the terminal hole 190C via a contact hole on the sixth layer 116 to the terminal hole 190C. The other end of the common line 14 extends from near the first terminal hole 191 via a contact hole to the noise countermeasure circuit 180 on the first layer 111.

[0060] On the fourth layer 114, the common line 14 is disposed at the boundary between the fourth conductive layer G4 and the fourth-layer circuit 114C, bends along the shape of the fourth conductive layer G4, and extends to a position where it overlaps with the noise suppression circuit 180. More specifically, the common line 14 extends from near the terminal hole 190C to the inductor 18 located on the opposite side of the terminal hole 190C with respect to the center of the substrate, then detours around the outside of the fourth conductive layer G4, bends toward the first terminal hole 191, and extends circumferentially. In other words, the common line 14 extends radially on the circular substrate, then bends circumferentially, and extends circumferentially again.

[0061] In Figure 6, the layout of the motor control unit 11 and the control signal line 15 arranged on the first layer 111 is indicated by dashed lines. In the fourth layer 114 of this embodiment, the common line 14 is formed in a curved shape that bypasses the fourth conductive layer G4 as described above, so the common line 14 does not divide the fourth conductive layer G4, and the control signal line 15 and the common line 14 do not overlap. On the other hand, the common line 14A of the comparative example is arranged to pass through a path that is shorter than that of this embodiment. As a result, the common line 14A divides the fourth conductive layer G4 and overlaps with the control signal line 15.

[0062] FIG. 7 is a diagram illustrating the noise reduction effect due to the arrangement of common line 14. The upper and lower diagrams in FIG. 7 show the measurement results of the noise level in control signal line 15. The upper diagram in FIG. 7 shows the noise level when the arrangement of common line 14A of the comparative example is adopted. The lower diagram in FIG. 7 shows the noise level when the arrangement of common line 14 of this embodiment is adopted. As can be seen from FIG. 7, by adopting the arrangement of common line 14 of this embodiment, the noise peak value around 100 MHz is about 6 dB lower than in the comparative example.

[0063] (Action and effect) As described above, the pump device 1 of this embodiment includes a motor 2 and an impeller 3 that is rotationally driven by the motor 2. The motor 2 includes a motor drive circuit board 19 on which a motor drive circuit 10 is mounted. The motor drive circuit 10 includes a power system circuit 170 including an inverter circuit 12 that outputs a drive current, and a signal system circuit 160 including a motor control unit 11 as a control element that supplies a control signal to the inverter circuit 12. The multilayer board 110 includes four layers stacked in this order: a first layer 111, a second layer 112, a third layer 113, and a fourth layer 114, and a ground pattern 100 is formed on each layer. A first layer circuit 111C is formed on the first layer 111, and the first layer circuit 111C includes the power system circuit 170, the signal system circuit 160, and a noise suppression circuit 180 that includes a capacitor. The fourth layer 114 is formed with a fourth layer circuit 114C including a power circuit 170, a fourth conductive layer G4 which is the ground pattern 100, and a common line 14 which connects the neutral point 65 of the three-phase coil 6 to the noise countermeasure circuit 180. The common line 14 is arranged at the boundary between the fourth layer circuit 114C and the fourth conductive layer G4, bends along the shape of the fourth conductive layer G4, and extends to the area where it overlaps with the noise countermeasure circuit 180.

[0064] In this embodiment, a multi-layer substrate 110 is used as the motor drive circuit board 19, so that high density The motor drive circuit 10 can be mounted on the multilayer substrate 110. A noise suppression circuit 180 including a capacitor is formed on the first layer 111 of the multilayer substrate 110, and the neutral point 65 of the three-phase coil 6 is connected to the noise suppression circuit 180 by a common wire 14 formed on the fourth layer 114. This smooths the voltage at the neutral point 65 and reduces noise generated in the motor 2. This improves EMC performance. Furthermore, on the fourth layer 114, the common wire 14 is arranged so as not to divide the fourth conductive layer G4. This prevents an increase in noise due to division of the ground pattern 100 and prevents a decrease in EMC performance.

[0065] In this embodiment, the noise suppression circuit 180 has a second capacitor 22 and a third capacitor 23 connected in series between the drive voltage line 13, to which the rated drive voltage is applied, and ground potential. An inductor 18 is connected in series to the drive voltage line 13, and the second capacitor 22 and the third capacitor 23 are connected in series between the drive voltage line 13 and ground potential on the input side of the inductor 18. The common line 14 connects the neutral point 65 to the midpoint between the second capacitor 22 and the third capacitor 23. As a result, the neutral point 65 is clamped by the second capacitor 22 and the third capacitor 23, making it possible to smooth the voltage at the neutral point 65. This reduces noise generated by the motor 2.

[0066] In this embodiment, the first layer 111 is provided with a control signal line 15 that supplies a PWM signal to the motor control unit 11, and the common line 14 and the control signal line 15 do not overlap. Therefore, noise on the PWM signal transmitted by the control signal line 15 can be reduced.

[0067] In this embodiment, the ground pattern 100 provided on the multilayer substrate 110 is a common ground pattern electrically connected to both the power circuit 170 and the signal circuit 160. The common ground pattern can be provided continuously and integrally over a wide area, thereby improving EMC performance.

[0068] In this embodiment, multilayer substrate 110 is composed of six layers stacked in this order: first layer 111, second layer 112, third layer 113, fourth layer 114, fifth layer 115, and sixth layer 116, and ground pattern 100 is formed on each layer. Ground pattern 100 is formed across the entire substrate on third layer 113 and fifth layer 115. Second layer circuit 112C including power circuit 170 is formed on second layer 112, fourth layer circuit 114C including power circuit 170 is formed on fourth layer 114, and sixth layer 116C including power circuit 170 is formed on sixth layer 116. Common line 14 is formed on fourth layer 114. Fourth layer 114 is a layer in which the area of ground pattern 100 on which power circuit 170 is provided is smaller than that of second layer 112. 5, comparing the second layer 112 and the fourth layer 114, the area where the fourth layer circuit 114C is arranged is larger than the area where the second layer circuit 112C is arranged. Therefore, the area of the fourth conductive layer G4 is smaller than the area of the second conductive layer G2. In this way, by arranging the common line 14 on a layer where the area of the ground pattern 100 is small, it is easy to prevent the common line 14 from dividing the ground pattern 100. Furthermore, even if the common line 14 detours around the ground pattern 100, the path of the common line 14 is unlikely to become long.

[0069] (Other embodiments) (1) The common line 14 may be provided on the second layer 112. Even when provided on the second layer 112, as in the case where the common line 14 is provided on the fourth layer 114, the common line 14 can be arranged at the boundary between the second-layer circuit 112C and the second conductive layer G2, bent along the shape of the second conductive layer G2, and formed so as to extend to the area where it overlaps with the noise suppression circuit 180. This makes it possible to suppress a deterioration in EMC performance due to the common line 14 dividing the second conductive layer G2. Furthermore, by preventing the common line 14 and the control signal line 15 from overlapping, noise can be reduced.

[0070] (2) The number of layers in a multilayer board is not limited to six. For example, the above-described multilayer board 110 includes the third layer 113 and the fifth layer 115 on which the ground pattern 100 is provided across the entire board, but these two layers can be eliminated to create a four-layer multilayer board. In this case, the fourth layer 114 in a six-layer board becomes the third layer. Therefore, the common line can be formed on the second or third layer.

[0071] (3) The noise suppression circuit 180 is not limited to the circuit of the above form, as long as it can clamp the neutral point 65 using a capacitor.

[0072] (summary) A summary of this disclosure is provided below. (1) A motor drive circuit board is provided on a multilayer substrate and includes a power system circuit including an inverter circuit that applies a drive voltage to three-phase coils, and a signal system circuit having a control element that supplies a control signal to the inverter circuit, the multilayer board includes four layers, namely, a first layer, a second layer, a third layer, and a fourth layer, stacked in this order, and a ground pattern is formed on each layer; a first layer circuit including the power circuit, the signal circuit, and a noise suppression circuit having a capacitor is formed on the first layer; When any one of the second layer, the third layer, and the fourth layer is designated as an Nth layer, The Nth layer is formed with an Nth layer circuit including the power circuit, an Nth conductive layer which is the ground pattern, and a common line which connects the neutral points of the three-phase coils and the noise suppression circuit, A motor drive circuit board characterized in that the common line is arranged at the boundary between the Nth layer circuit and the Nth conductive layer, bends along the shape of the Nth conductive layer, and extends to an area overlapping with the noise countermeasure circuit.

[0073] (2) the noise suppression circuit includes two of the capacitors connected in series between a drive voltage line to which a rated drive voltage is applied and a ground potential, The motor drive circuit board according to (1) above, wherein the common line connects the neutral point and a midpoint between the two capacitors.

[0074] (3) A control signal line for supplying a PWM signal to the control element is formed on the first layer, The motor drive circuit board according to (1) or (2) above, wherein the common line and the control signal line do not overlap.

[0075] (4) The motor drive circuit board according to any one of (1) to (3) above, characterized in that the ground pattern is a common ground pattern electrically connected to both the power system circuits and the signal system circuits.

[0076] (5) the multilayer board is made up of six layers stacked in the order of the first layer, the second layer, the third layer, the fourth layer, the fifth layer, and the sixth layer, and the ground pattern is formed on each layer; the ground patterns are formed on the third and fifth layers over the entire substrate; a second layer circuit including the power system circuit is formed on the second layer; a fourth layer circuit including the power system circuit is formed on the fourth layer; a sixth layer circuit including the power system circuit is formed on the sixth layer; The motor drive circuit board according to any one of (1) to (4) above, wherein the Nth layer on which the common line is formed is the second layer or the fourth layer.

[0077] (6) The motor drive circuit board according to (5) above, wherein the Nth layer is the layer having the smaller area of the ground pattern between the second layer and the fourth layer.

[0078] (7) A motor drive circuit board according to any one of (1) to (6) above; and the three-phase coils to which a drive voltage is applied from the inverter circuit.

[0079] (8) The motor according to (7) above; an impeller that is rotationally driven by the motor. [Explanation of symbols]

[0080] 1...pump device, 2...motor, 3...impeller, 4...case, 5...rotor, 6...coil, 7...stator, 8...resin sealing member, 9...cover, 10...motor drive circuit, 11...motor control unit, 12...inverter circuit, 13...drive voltage line, 14, 14A...common line, 15...control signal line, 16...FG output line, 17...ground line, 18...inductor, 19...motor drive circuit board, 20...pump chamber, 21...first capacitor, 22...second capacitor, 23...third capacitor, 24...fourth capacitor, 25...fifth capacitor, 26...sixth Capacitor, 27...7th capacitor, 28...8th capacitor, 29...ferrite bead, 31...diode, 41, 42, 43, 44, 45, 46...filter, 51, 52, 53...capacitor, 61...U-phase coil, 62...V-phase coil, 63...W-phase coil, 65...neutral point, 70...stator core, 71...insulator, 72...winding terminal, 73...core connecting wire, 80...connector housing, 100...ground pattern, 110...multilayer board, 111...first layer, 111C...first layer circuit, 112...second layer, 112C...second layer circuit, 1 13...third layer, 114, 114A...fourth layer, 114C...fourth layer circuit, 115...fifth layer, 116...sixth layer, 116C...sixth layer circuit, 121...output line, 131...first line, 132...second line, 151...third line, 160...signal circuit, 170...power circuit, 180...noise suppression circuit, 181...inductor, 190U, 190V, 190W, 190C...terminal hole, 191...first terminal hole, 192...second terminal hole, 193...third terminal hole, 194...fourth terminal hole, 195...connector terminal hole, 196...straight portion, 197...protruding portion, 751...constant voltage Crimp terminal, 752...first signal terminal, 753...second signal terminal, 754...ground terminal, D31, D32, D33...diode, G1...first conductive layer, G2...second conductive layer, G3...third conductive layer, G4...fourth conductive layer, G5...fifth conductive layer, G6...sixth conductive layer, L...rotation axis, L1...one side in the axial direction, L2...other side in the axial direction, Q1, Q2, Q3, Q4, Q5, Q6...switching element, Q7...NOT gate, R1, R2, R3, R11, R21, R31, R32, R33...resistor, Rs...shunt resistor, S1...one side, S2...other side

Claims

1. A motor drive circuit board is provided on a multilayer substrate and includes a power system circuit including an inverter circuit that applies a drive voltage to three-phase coils, and a signal system circuit having a control element that supplies a control signal to the inverter circuit, the multilayer board includes four layers, namely, a first layer, a second layer, a third layer, and a fourth layer, stacked in this order, and a ground pattern is formed on each layer; a first layer circuit including the power circuit, the signal circuit, and a noise suppression circuit having a capacitor is formed on the first layer; When any one of the second layer, the third layer, and the fourth layer is designated as an Nth layer, The Nth layer is formed with an Nth layer circuit including the power circuit, an Nth conductive layer which is the ground pattern, and a common line which connects the neutral points of the three-phase coils and the noise suppression circuit, A motor drive circuit board characterized in that the common line is arranged at the boundary between the Nth layer circuit and the Nth conductive layer, bends along the shape of the Nth conductive layer, and extends to an area overlapping with the noise countermeasure circuit.

2. the noise suppression circuit includes two of the capacitors connected in series between a drive voltage line to which a rated drive voltage is applied and a ground potential; 2. The motor drive circuit board according to claim 1, wherein the common line connects the neutral point and a midpoint between the two capacitors.

3. A control signal line for supplying a PWM signal to the control element is formed on the first layer, 3. The motor drive circuit board according to claim 2, wherein the common line and the control signal line do not overlap.

4. 4. The motor drive circuit board according to claim 3, wherein the ground pattern is a common ground pattern electrically connected to both the power system circuit and the signal system circuit.

5. the multilayer board is made up of six layers stacked in the order of the first layer, the second layer, the third layer, the fourth layer, the fifth layer, and the sixth layer, and the ground pattern is formed on each layer; the ground patterns are formed on the third and fifth layers over the entire substrate; a second layer circuit including the power system circuit is formed on the second layer; a fourth layer circuit including the power system circuit is formed on the fourth layer; a sixth layer circuit including the power system circuit is formed on the sixth layer; 5. The motor drive circuit board according to claim 4, wherein the Nth layer on which the common line is formed is the second layer or the fourth layer.

6. 6. The motor drive circuit board according to claim 5, wherein the Nth layer is the layer having the smaller area of the ground pattern between the second layer and the fourth layer.

7. A motor drive circuit board according to any one of claims 1 to 6; the three-phase coils to which a drive voltage is applied from the inverter circuit.

8. a motor according to claim 7; an impeller that is rotationally driven by the motor.

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