Motor drive circuit board, motor, and pump device

Abstract

A motor 2 for a pump device 1 comprises a motor drive circuit board 19 provided with a motor drive circuit 10 including: a power system circuit 170 including a motor driver IC 12 incorporating a switching element for generating a drive voltage to be applied to a three-phase coil 6; and a signal system circuit 160 including a motor control unit 11 for supplying a control signal to the motor driver IC 12. The motor driver IC 12 is mounted on a first board surface S1 of the motor drive circuit board 19. A ground pattern 100 formed on the first board surface S1 includes a noise guard part Gn disposed between a region of the first board surface S1 where the power system circuit 170 is disposed and the outer peripheral edge of the board. The noise guard part Gn extends continuously from one end in the circumferential direction of the region where the power system circuit 170 is disposed to the other end in the circumferential direction.

Description

Motor drive circuit board, motor and pump device

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

[0002] In recent years, circuit boards on which motor drive circuits are mounted are required to meet EMC (Electromagnetic Compatibility), which 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 motor drive circuit includes an inverter circuit that supplies drive current to three-phase coils. Therefore, the board on which the motor drive circuit is mounted requires space to accommodate the switching elements that make up the inverter circuit, resulting in an increased board size. Furthermore, to counter noise generated by the switching elements, a ground pattern that functions as a noise shield is provided on the board. Patent Document 1 describes this type of motor drive circuit board.

[0004] Japanese Patent Application Laid-Open No. 2023-056661

[0005] The motor drive circuit board of Patent Document 1 uses a multilayer board in which multiple layers, each with a wiring pattern that constitutes the circuit, are stacked with an insulating layer interposed between them in order to mount circuits at high density on the board. Six switching elements are mounted on the first layer of the multilayer board. The first layer also mounts a control element that supplies a control signal to the inverter circuit, a capacitor for noise suppression, and other components. Therefore, even with a multilayer board, it is necessary to ensure space for these elements, making it difficult to miniaturize the board. Furthermore, it is difficult from a layout perspective to ensure a large ground pattern on the layer where the switching elements are mounted to improve EMC performance.

[0006] In view of the above problems, an object of the present invention is to reduce the size of a board on which a motor drive circuit is mounted, and to improve EMC performance by increasing the shielding effect against noise generated from an inverter circuit.

[0007] In order to solve the above problem, one aspect of a circuit board for a motor drive circuit according to the present invention is a motor drive circuit board provided with a motor drive circuit comprising: a power system circuit including a motor driver IC incorporating switching elements for generating drive voltages to be applied to three-phase coils; and a signal system circuit including control elements for supplying control signals to the motor driver IC; the circuit board has a first board surface on which at least the motor driver IC is mounted; a ground pattern is formed on the first board surface; the ground pattern comprises a noise guard portion arranged between the placement area of ​​the power system circuit on the first board surface and the outer periphery of the board; and the noise guard portion extends continuously from one circumferential end of the placement area to the other circumferential end of the placement area.

[0008] Next, one aspect of the motor according to the present invention is characterized by having the above motor drive circuit board and the three-phase coils to which a drive voltage is applied from the motor driver IC.

[0009] 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.

[0010] Fig. 1 is a cross-sectional view of a pump device equipped with a motor. Fig. 2 is a plan view of a motor drive circuit board. Fig. 3 is a block diagram showing the schematic configuration of a motor drive control system. Fig. 4 is a circuit diagram of a motor drive circuit mounted on the motor drive circuit board. Fig. 5 is an explanatory diagram showing the configuration of each layer of a multi-layer board.

[0011] 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.

[0012] (Pump Device) Fig. 1 is a cross-sectional view of a pump device 1 including a motor 2. As shown in Fig. 1, 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. The resin sealing member 8 is provided with a connector portion (not shown) that holds a plurality of connector terminals for external connection.

[0013] The impeller 3 is disposed in a pump chamber 20 defined by the resin sealing member 8 and the case 4 of the motor 2. The impeller 3 and the 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.

[0014] Metal winding terminals 72 that penetrate the bottom of the resin sealing member 8 from the stator 7 and protrude to the other axial side L2 are soldered to the motor drive circuit board 19. In this embodiment, four winding terminals 72 are soldered to the motor drive circuit board 19. In addition, connector terminals (not shown) that are held in the connector portion of the resin sealing member 8 described above are soldered to the motor drive circuit board 19.

[0015] 2 is a plan view of the motor drive circuit board 19. The motor drive circuit board 19 has a first board surface S1 facing one side L1 in the axial direction. The first board surface S1 faces the bottom of the resin sealing member 8. The motor drive circuit board 19 has electronic elements such as a motor driver IC 12 (described later) mounted on the first board surface S1.

[0016] The motor drive circuit board 19 has a linearly cut-out linear portion 196 on its outer periphery. Two notches 197 are provided on both circumferential sides of the linear portion 196 to serve as fixing portions for fixing the motor drive circuit board 19 to the bottom of the resin sealing member 8. The motor drive circuit board 19 is fixed to the bottom of the resin sealing member 8 by tapping screws that pass through the two notches 197 (fixing portions). The motor drive circuit board 19 is positioned in the circumferential direction by fitting protrusions provided on the resin sealing member 8 into three notches 199 provided on the radially opposite side of the linear portion 196.

[0017] 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. The four winding terminals 72 shown in FIG. 1 have their tips on the other axial side L2 fitted into and soldered to the terminal holes 190U, 190V, 190W, and 190C of the motor drive circuit board 19. As a result, the three-phase coils 6 are electrically connected to the motor drive circuit board 19 via the winding terminals 72.

[0018] A first terminal hole 191, a second terminal hole 192, a third terminal hole 193, and a fourth terminal hole 194 are provided on the outer periphery of the motor drive circuit board 19, and are aligned along a straight portion 196. Four connector terminals held in the connector portion of the resin sealing member 8 are fitted into the first terminal hole 191, the second terminal hole 192, the third terminal hole 193, and the fourth terminal hole 194 and soldered thereto.

[0019] 3 is a block diagram showing the schematic configuration of the drive control system of the motor 2. A motor driver IC 12 for supplying drive current to the three-phase coils 6 provided in the motor mechanism unit 2A and a motor control unit 11 for supplying control signals to the motor driver IC 12 are mounted on the motor drive circuit board 19. The motor control unit 11 is a control element formed by an IC chip such as an MCU (Micro Controller Unit). The motor driver IC 12 is an electronic element in which switching elements constituting an inverter circuit are integrated on a single chip. For example, the motor driver IC 12 incorporates six FETs (Field Effect Transistors) as switching elements for the three-phase coils 6.

[0020] A drive voltage of rated 12 V is applied to the motor driver IC 12 from an external power supply. The motor control unit 11 receives a PWM signal from a higher-level device and outputs an FG signal, which is a rotation speed signal corresponding to the rotation speed of the motor 2, to the higher-level device. Between the motor driver IC 12 and the motor control unit 11, wiring for power supply and signal lines for transmitting various signals such as control signals, FG signals, and abnormality detection signals are provided.

[0021] 2, control elements constituting the motor control unit 11 and the motor driver IC 12 are mounted on the first board surface S1 of the motor drive circuit board 19. In addition, electronic elements for noise suppression, such as an inductor 18, are mounted on the first board surface S1. The inductor 18 is, for example, a choke coil.

[0022] 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 to which an FG signal is output, and a ground terminal 754 to which a ground potential is applied.

[0023] The constant voltage terminal 751, the first signal terminal 752, the second signal terminal 753, and the ground terminal 754 are connector terminals held in the connector portion of the resin sealing member 8 described above. As shown in Fig. 2, the first terminal hole 191 into which the constant voltage terminal 751 fits and the fourth terminal hole 194 into which the ground terminal 754 fits are located at both ends of a straight portion 196 on the motor drive circuit board 19. The second terminal hole 192 into which the first signal terminal 752 fits and the third terminal hole 193 into which the second signal terminal 753 fits are located between the first terminal hole 191 and the fourth terminal hole 194.

[0024] 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. One end of the winding constituting each of the U-phase coil 61, the V-phase coil 62, and the W-phase coil 63 is electrically connected to winding terminals 72 soldered to terminal holes 190U, 190V, and 190W. In this embodiment, one of the four winding terminals 72 is a common terminal. The other end of the winding constituting each of the U-phase coil 61, the V-phase coil 62, and the W-phase coil 63 is electrically connected to the common terminal. The common terminal is soldered to terminal hole 190C.

[0025] As shown in Figure 4, the motor drive circuit 10 includes a motor control unit 11 and a motor driver IC 12. The motor control unit 11 controls the rotation of the rotor 5 in the motor mechanism unit 2A using a PWM signal. The motor driver IC 12 has a built-in inverter circuit that generates a drive voltage to be supplied to the three-phase coils 6 based on the output signal from the motor control unit 11. A drive voltage line 13 for supplying power is connected to the motor driver IC 12. A drive voltage of rated 12 V is applied to the drive voltage line 13 via a constant voltage terminal 751.

[0026] Based on a PWM signal input from an external device, the motor control unit 11 outputs an output signal for controlling the motor driver IC 12. The motor control unit 11 also outputs a rotation speed signal to the external device corresponding to the rotation speed of the rotor 5. Based on the rotation speed signal, the external device outputs a PWM signal to the motor control unit 11 to set the motor 2 to a desired rotation speed.

[0027] The three-phase coils 6 are connected in a star connection. As shown in Figure 4, the motor drive circuit 10 includes a common line 14 connected to the neutral point 65 of the three-phase coils 6, and a core connection line 73 electrically connected to the stator core 70. The core connection line 73 is electrically connected to a ground pattern 100 provided on the motor drive circuit board 19.

[0028] 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 rotor 5 is output to an external device via a second signal terminal 753, and a ground line 17 connected to a ground terminal 754.

[0029] The motor drive circuit 10 includes a first line 21, a second line 22, a third line 23, a fourth line 24, a fifth line 25, and a sixth line 26 that connect the motor control unit 11 and the motor driver IC 12. The first line 21 is a power supply line that supplies power to the motor control unit 11. The second line 22, the third line 23, the fourth line 24, the fifth line 25, and the sixth line 26 include signal lines that output control signals based on PWM signals from the motor control unit 11, signal lines that output FG signals and abnormality detection signals from the motor driver IC 12, and the like.

[0030] The second line 22, the third line 23, the fourth line 24, the fifth line 25, and the sixth line 26 are each connected to a branch line branching off from the first line 21. A resistor R4 is connected in series to the branch line connected to the second line 22. A resistor R5 is connected in series to the branch line connected to the third line 23. A resistor R6 is connected in series to the branch line connected to the fourth line 24. A resistor R7 is connected in series to the branch line connected to the fifth line 25. A resistor R8 is connected in series to the branch line connected to the sixth line 26.

[0031] Based on the control signal output by the motor control unit 11, the motor driver IC 12 converts the drive voltage supplied from the drive voltage line 13 into a three-phase AC drive voltage by switching the switching elements, and supplies it to the U-phase coil 61, the V-phase coil 62, and the W-phase coil 63.

[0032] 4, the motor drive circuit 10 includes, as noise suppression electronic elements, an inductor 18, capacitors C1 to C9, and a diode 31. The inductor 18 is connected in series to the drive voltage line 13. The capacitors C1 to C4 and the diode 31 are each electrically connected between the drive voltage line 13 and the ground pattern 100.

[0033] Capacitor C1 is placed immediately before inductor 18. Capacitor C2 is placed immediately after inductor 18. Capacitors C1 and C2 are electrolytic capacitors. The three elements, inductor 18 and capacitors C1 and C2, function as a π-type low-pass filter, cutting out high-frequency noise from the power supply side. A diode 31 is placed in front of capacitor C1. Diode 31 protects the elements in motor drive circuit 10 from surge voltages.

[0034] Capacitor C3 is arranged in the stage preceding diode 31. Capacitor C3 has a smaller capacitance than capacitor C1. Therefore, the capacitances of the capacitors connected to drive voltage line 13 are arranged in order of increasing capacitance from the power supply side toward inductor 18. As a result, on the power supply side of capacitor C1, high-frequency noise (e.g., MHz-class noise) is reduced first by capacitor C3 than noise that can be reduced by capacitor C1 (e.g., kHz-class noise).

[0035] Capacitor C4 is arranged after capacitor C2. Capacitor C4 has a smaller capacitance than capacitor C2. Therefore, the capacitors connected to drive voltage line 13 are arranged in order of increasing capacitance from motor driver IC 12 toward inductor 18. This allows capacitor C4 to reduce high-frequency noise (e.g., MHz-class noise) earlier than noise that can be reduced by capacitor C2 (e.g., kHz-class noise) on the motor driver IC 12 side than capacitor C2.

[0036] On the input side of the capacitor C3, the capacitors C5 and C6 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 capacitors C5 and C6. The ground terminal 754 is electrically connected between the capacitor C6 and the ground pattern 100.

[0037] As a result, the neutral point 65 electrically connected to the common line 14 is clamped by the capacitors C5 and C6, so that even if a voltage with a relatively large amplitude occurs at the neutral point 65, the voltage at the neutral point 65 is smoothed. Therefore, noise generated in the motor 2 can be suppressed.

[0038] Capacitors C7 and C8 and a resistor R3 are connected to the control signal line 15. The capacitors C7 and C8 are electrically connected between the control signal line 15 and the ground pattern 100. The resistor R3 is connected in series to a portion of the control signal line 15 subsequent to the capacitor C7. The capacitor C8 is connected to a portion of the control signal line 15 subsequent to the resistor R3. The capacitors C7 and C8 can level the PWM signal transmitted through the control signal line 15, thereby reducing noise generated in the control signal line 15.

[0039] When the resistor R3 and the first signal terminal 752 in the control signal line 15 are electrically connected to the ground pattern 100 via the capacitor C7 as described above, a seventh line 27 branching from the first line 21 is connected between the capacitor C7 and the resistor R3. A resistor R2 is electrically connected in series to the seventh line 27.

[0040] A capacitor C9, a resistor R1, and a NOT gate Q7 are connected to the FG output line 16. The capacitor C9 is electrically connected between the FG output line 16 and the ground pattern 100. This allows the rotation speed signal generated in the FG output line 16 to be leveled, thereby reducing noise generated in the FG output line 16.

[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 capacitor C9. 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 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. In a multilayer board, 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, the relatively low-voltage circuits including motor control unit 11 and circuits for inputting and outputting control signals are referred to as signal system circuits 160. Furthermore, the relatively high-voltage circuits including wiring for connecting motor driver IC 12 and three-phase coils 6 are referred to as power system circuits 170. Furthermore, a circuit in which noise suppression electronic elements such as capacitors are electrically connected to drive voltage lines 13 is referred to as noise suppression circuit 180. As described above, common line 14 is routed to connect neutral points 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 board 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] The multilayer board has four layers, a first layer 111, a second layer 112, a third layer 113, and a fourth layer 114, as shown in FIG. 5. The uppermost first layer 111 is formed on the first board surface S1. Lands (not shown) on which electrical elements are mounted are formed. A conductive layer that functions as a ground pattern 100 is formed on all layers of the multilayer board.

[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, and a fourth conductive layer G4 formed on the fourth layer 114. In Fig. 5, the areas where these conductive layers are formed are shown as hatched areas.

[0047] 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 an area surrounded by a dashed line.

[0048] 5 shows the approximate layout area of ​​the electrical elements, wiring, conductive layers, etc. that make up the circuit, and does not show fine wiring, contact holes, etc. Conductive layers are not formed around contact holes or wiring.

[0049] Motor drive circuit 10 includes first layer circuit 111C provided on first layer 111 and third layer circuit 113C provided on third layer. First layer circuit 111C includes signal circuit 160, power circuit 170, and noise suppression circuit 180. Third layer circuit 113C includes signal circuit 160. Therefore, in this embodiment, power circuit 170 is entirely disposed on first layer 111.

[0050] 5 , on the first layer 111, the layout area of ​​the signal system circuits 160 extends from the position of the motor control unit 11 located in the central region of the board to the second terminal hole 192 to which the first signal terminal 752 is connected and the third terminal hole 193 to which the second signal terminal 753 is connected. The layout area of ​​the power system circuits 170 extends from the position of the motor driver IC located in the central region of the board to the opposite side of the signal system circuits 160, and extends to the positions of terminal holes 190U, 190V, 190W, and 190C to which the three-phase coil 6 and common terminals are connected. The noise suppression circuit 180 is located 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 disposed in a region surrounding the peripheries of the power circuit 170 and the signal circuit 160, and in a region between the anti-noise circuit 180 and the signal circuit 160. The first conductive layer G1 is not formed in a region overlapping with the inductor 18. The first conductive layer G1 surrounds the entire periphery of the power circuit 170, except for the region overlapping with the inductor 18. The portion of the first conductive layer G1 surrounding the power circuit 170 includes a noise guard portion Gn disposed between the power circuit 170 and the outer periphery of the substrate. The noise guard portion Gn continuously surrounds the outer periphery of the power circuit 170 along the outer periphery of the substrate. In other words, the noise guard portion Gn extends continuously from one circumferential end of the placement area of ​​the power circuit 170 to the other circumferential end of the placement area of ​​the power circuit 170.

[0052] In this embodiment, the area of ​​the first conductive layer G1 on the first substrate surface S1 is 50% or more of the area of ​​the region on the first substrate surface S1 where the elements and wiring that make up the motor drive circuit 10 are arranged.

[0053] In all layers of the multilayer board, the ground pattern 100 is not formed in a portion that overlaps with the inductor 18. As shown in Fig. 5, each of the second conductive layer G2, the third conductive layer G3, and the fourth conductive layer G4 has a hollowed-out shape in the portion that overlaps with the inductor 18.

[0054] The arrangement area of ​​the signal circuit 160 on the third layer 113 is surrounded on all sides by the second conductive layer G2. On the second layer 112, the second conductive layer G2 is formed on the entire substrate except for the portion overlapping with the inductor 18. Similarly, on the fourth layer 114, the fourth conductive layer G4 is formed on the entire substrate except for the portion overlapping with the inductor 18.

[0055] The ground pattern 100 of the multilayer board extends continuously along the outer periphery of the board on each layer. The ground pattern 100 extending along the outer periphery of the board is connected to the ground patterns 100 on the upper and lower layers by through holes (not shown). This reduces noise radiation to the outside of the board.

[0056] 5 , the common line 14 is formed on the first layer 111. The common line 14 extends from a terminal hole 190C to which a common terminal is connected to the noise countermeasure circuit 180. In the first layer 111, the common line 14 extends from the terminal hole 190C toward the outer periphery and extends circumferentially along the outer shape of the first conductive layer G1 to the noise countermeasure circuit 180. Therefore, the common line 14 does not divide the ground pattern 100 that surrounds the outer periphery of the power circuit 170.

[0057] (Operation 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 provided, the motor drive circuit 10 including a power system circuit 170 including a motor driver IC 12 that incorporates switching elements for generating drive voltages to be applied to three-phase coils 6, and a signal system circuit 160 including a motor control unit 11 as a control element that supplies control signals to the motor driver IC 12. The motor drive circuit board 19 has a first board surface S1 on which at least the motor driver IC 12 is mounted. A first conductive layer G1, which is a ground pattern 100, is formed on the first board surface S1. The first conductive layer G1 includes a noise guard portion Gn that is disposed between the arrangement area of ​​the power system circuit 170 on the first board surface S1 and the outer periphery of the board. The noise guard portion Gn extends continuously from one circumferential end of the arrangement area of ​​the power system circuit 170 to the other circumferential end of the arrangement area of ​​the power system circuit 170.

[0058] In this embodiment, the power circuit 170 of the motor drive circuit 10 is configured using a motor driver IC 12 with built-in switching elements. By packaging a switching element such as an FET and a motor driver in a single-chip IC, the switching element does not need to be externally attached to the IC. This eliminates the need for space on the board to individually mount the switching elements, eliminating the need to secure a large space for mounting the power circuit 170 including the switching elements. This allows the motor drive circuit board 19 to be made smaller. Furthermore, by packaging the switching elements, radiation noise from the switching elements can be reduced, improving EMC performance.

[0059] Furthermore, since the layout area of ​​the power circuit 170 can be reduced, a large space can be secured on the first board surface S1 for providing the ground pattern 100, which functions as a shielding layer for EMC measures. In this embodiment, the ground pattern 100 has a noise guard portion Gn and is configured to continuously surround the outer periphery of the power circuit 170. This effectively suppresses noise radiation from the power circuit 170 to the outside of the board. This improves the shielding effect and EMC performance.

[0060] In this embodiment, on the first board surface S1, the ground pattern 100 is configured to completely surround the layout area of ​​the power circuit 170. This can improve EMC performance.

[0061] In this embodiment, the area of ​​the ground pattern 100 on the first substrate surface S1 is 50% or more of the area of ​​the region on the first substrate surface S1 where the elements and wiring that make up the motor drive circuit 10 are arranged. As described above, if the layout area of ​​the power circuit 170 can be reduced, a large area can be secured for the ground pattern 100. In other words, even if the entire power circuit 170 is arranged on the first substrate surface S1, the area of ​​the ground pattern 100 can be made 50% or more of the layout area of ​​the motor drive circuit 10. This can improve EMC performance.

[0062] In this embodiment, the motor control unit 11 as a control element is mounted on the first board surface S1. At least a portion of the signal system circuits 160 is arranged on the first board surface S1. As described above, if the layout area of ​​the power system circuits 170 can be reduced, the entire power system circuits 170 and most of the signal system circuits 160 can be arranged on the first board surface S1. Therefore, there is no need to distribute and mount electronic elements on both sides of the board.

[0063] In this embodiment, the ground pattern 100 is a common ground pattern that is electrically connected to both the power circuit 170 and the signal circuit 160. A common ground pattern can be provided continuously and integrally over a wide area, thereby improving EMC performance.

[0064] In this embodiment, the motor drive circuit 10 is formed on a multilayer substrate including a first layer 111 that constitutes a first substrate surface S1. The multilayer substrate includes four layers stacked in this order: the first layer 111, the second layer 112, the third layer 113, and the fourth layer 114, and a ground pattern 100 is formed on each layer. The ground pattern 100 is a common ground pattern electrically connected to both the power system circuit 170 and the signal system circuit 160. The motor control unit 11 serving as a control element is mounted on the first layer 111, and in addition to the power system circuit 170, a portion of the signal system circuit 160 is also arranged. The ground pattern 100 is formed on the second layer 112 and the fourth layer 114 across the entire substrate. On the third layer 113, a portion of the signal system circuit 160 is arranged in an area completely surrounded by the ground pattern 100.

[0065] In this way, by using a multilayer board, it is possible to miniaturize the board while ensuring space for mounting the motor drive circuit 10 and the area of ​​the ground pattern 100. Therefore, EMC performance is improved and the motor drive circuit board 19 can be miniaturized. That is, in this embodiment, since circuit placement space can be secured on the third layer 113, it is not necessary to place the entire motor drive circuit 10 on the first layer 111. Therefore, the area for the ground pattern 100 on the first layer 111 can be secured, and the shielding effect against noise radiation from the power circuit 170 can be improved. Furthermore, by alternately stacking layers on which circuits are placed and layers on which the entire board is covered by the ground pattern 100, the shielding effect can be improved. Therefore, EMC performance can be improved.

[0066] In this embodiment, the entire power system circuit 170 is placed in the placement area. A portion of the signal system circuit 160 is placed on the third layer 113. As described above, by using the motor driver IC 12 with a built-in switching element, the placement area of ​​the power system circuit 170 can be reduced. Therefore, the power system circuit 170 can be placed in a concentrated manner on the first layer 111, and the entire periphery can be surrounded by the ground pattern 100.

[0067] In this embodiment, a noise countermeasure circuit 180 is arranged on the first substrate surface S1, the noise countermeasure circuit 180 including an inductor 18 connected in series to a drive voltage line 13 to which a rated drive voltage is applied, and two capacitors C5 and C6 connected in series between the drive voltage line and ground potential on the input side of the inductor 18, and a common line 14 is formed connecting a neutral point 65 of the three-phase coil 6 and a midpoint between the two capacitors C5 and C6. The common line 14 extends along the outer periphery of the ground pattern 100 to the noise countermeasure circuit 180.

[0068] This circuit configuration smooths the voltage at the neutral point 65, reducing noise generated by the motor 2. This improves EMC performance. Furthermore, the common line 14 extends to the noise suppression circuit 180 along the outer periphery of the ground pattern 100, and does not divide the ground pattern 100. This prevents an increase in noise due to division of the ground pattern 100, and also prevents a decrease in EMC performance.

[0069] (Other Embodiments) (1) In the above embodiment, the motor drive circuit board 19 is a multilayer board, but it does not have to be a multilayer board. For example, the signal system circuit 160 disposed on the third layer 113 in this embodiment can be disposed on a second board surface behind the first board surface S1. In this case, the ground pattern 100 is formed on the second board surface so as to surround the entire periphery of the signal system circuit 160.

[0070] (2) The circuits arranged on the first substrate surface S1 are not limited to the above configuration. For example, a portion of the power circuit 170 may be arranged on the third layer 113. Furthermore, the entire signal circuit 160 may be arranged on the first substrate surface S1.

[0071] (3) The ground pattern 100 provided on the first substrate surface S1 does not have to completely surround the layout area of ​​the power circuit 170. If a noise guard portion Gn is provided that continuously surrounds at least the outer periphery of the power circuit 170, noise radiation outside the substrate can be effectively suppressed.

[0072] (Summary) The present disclosure is summarized below: (1) A motor drive circuit board provided with a motor drive circuit including: a power system circuit including a motor driver IC having a built-in switching element for generating drive voltages to be applied to three-phase coils; and a signal system circuit including a control element for supplying control signals to the motor driver IC, the motor drive circuit board having a first board surface on which at least the motor driver IC is mounted, a ground pattern formed on the first board surface, the ground pattern including a noise guard portion disposed between an arrangement area of ​​the power system circuit on the first board surface and an outer periphery of the board, the noise guard portion extending continuously from one circumferential end of the arrangement area to the other circumferential end of the arrangement area.

[0073] (2) The motor drive circuit board according to (1) above, characterized in that the area of ​​the ground pattern on the first substrate surface is 50% or more of the area of ​​the region on the first substrate surface where the elements and wiring that constitute the motor drive circuit are arranged.

[0074] (3) The motor drive circuit board according to (1) or (2) above, wherein the entire power circuit is disposed on the first board surface.

[0075] (4) The motor drive circuit board according to any one of (1) to (3) above, wherein the ground pattern surrounds the entire periphery of the arrangement area.

[0076] (5) The motor drive circuit board according to any one of (1) to (4) above, characterized in that the control element is mounted on the first substrate surface, and at least a part of the signal system circuit is arranged on the first substrate surface.

[0077] (6) The motor drive circuit board according to any one of (1) to (5) above, wherein the ground pattern is a common ground pattern electrically connected to both the power system circuits and the signal system circuits.

[0078] (7) The motor drive circuit board according to any one of (1) to (4) above, characterized in that the motor drive circuit is formed on a multilayer board including a first layer constituting the first board surface, the multilayer board includes four layers stacked in the order of the first layer, second layer, third layer, and fourth layer, and the ground pattern is formed on each layer, the control element is mounted on the first layer, the ground pattern is formed on the second layer and the fourth layer over the entire board, the ground pattern is a common ground pattern electrically connected to both the power system circuit and the signal system circuit, and on the third layer, a part of the power system circuit or the signal system circuit is arranged in an area completely surrounded by the ground pattern.

[0079] (8) The motor drive circuit board according to (7) above, characterized in that the entire power system circuit is arranged in the arrangement region, and part of the signal system circuit is arranged on the third layer.

[0080] (9) A motor comprising: the motor drive circuit board according to any one of (1) to (8) above; and the three-phase coils to which a drive voltage is applied from the inverter circuit.

[0081] (10) A pump device comprising: the motor according to (9) above; and an impeller that is rotationally driven by the motor.

[0082] 1...pump device, 2...motor, 2A...motor mechanism part, 3...impeller, 4...case, 5...rotor, 6...coil, 7...stator, 8...resin sealing member, 9...cover, 10...motor drive circuit, 11...motor control part, 12...motor driver IC, 13...drive voltage line, 14...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 line, 22...second line, 23...third line, 24...fourth line, 25...fifth line, 26...sixth line, 27...seventh line, 31...diode, 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, 100...Ground pattern, 111...First layer, 111C...First layer circuit, 112...Second layer, 113...Third layer, 113C...Third layer circuit, 114...Fourth layer, 160...Signal system circuit, 170...Power system circuit, 180...Noise suppression circuit, 190U, 190V, 190W, 190C...Terminal hole, 191...First terminal hole, 192...Second terminal hole, 193...Third terminal hole, 194...Fourth terminal hole, 196...Straight portion, 197...Notch, 751...Constant voltage terminal, 752...First signal terminal, 753...Second signal terminal, 754...Ground terminal, C1, C2, C3, C4, C5 , C6, C7, C8, C9...capacitors, G1...first conductive layer, G2...second conductive layer, G3...third conductive layer, G4...fourth conductive layer, Gn...noise guard section, L...rotation axis, Q7...NOT gate, R1, R2, R3, R4, R5, R6, R7, R8...resistors, S1...first substrate surface

Claims

1. A motor drive circuit board provided with a motor drive circuit comprising: a power system circuit with a motor driver IC that incorporates switching elements for generating drive voltages to be applied to three-phase coils; and a signal system circuit with control elements that supply control signals to the motor driver IC, the motor drive circuit board having a first board surface on which at least the motor driver IC is mounted; a ground pattern formed on the first board surface; the ground pattern comprising a noise guard section that is arranged between the power system circuit arrangement area on the first board surface and the outer periphery of the board; and the noise guard section extending continuously from one circumferential end of the arrangement area to the other circumferential end of the arrangement area.

2. A motor drive circuit board as described in claim 1, characterized in that the area of ​​the ground pattern on the first board surface is 50% or more of the area of ​​the region on the first board surface in which the elements and wiring that make up the motor drive circuit are arranged.

3. The motor drive circuit board according to claim 1 or 2, wherein the entire power circuit is disposed on the first board surface.

4. The motor drive circuit board according to any one of claims 1 to 3, wherein the ground pattern surrounds the entire periphery of the arrangement area.

5. A motor drive circuit board according to any one of claims 1 to 4, characterized in that the control element is mounted on the first board surface, and at least a portion of the signal system circuit is arranged on the first board surface.

6. The motor drive circuit board according to any one of claims 1 to 5, wherein the ground pattern is a common ground pattern electrically connected to both the power system circuits and the signal system circuits.

7. A motor drive circuit board as claimed in any one of claims 1 to 4, characterized in that: the motor drive circuit is formed on a multilayer board including a first layer constituting the first board surface; the multilayer board includes four layers stacked in the order of the first layer, second layer, third layer, and fourth layer, and the ground pattern is formed on each layer; the control element is mounted on the first layer; the ground pattern is formed on the second layer and the fourth layer over the entire board; the ground pattern is a common ground pattern electrically connected to both the power system circuit and the signal system circuit; and on the third layer, a part of the power system circuit or the signal system circuit is arranged in an area completely surrounded by the ground pattern.

8. The motor drive circuit board according to claim 7, wherein the entire power circuit is arranged in the arrangement area, and a part of the signal circuit is arranged on the third layer.

9. A motor comprising: a motor drive circuit board according to any one of claims 1 to 8; and the three-phase coils to which a drive voltage is applied from the motor driver IC.

10. A pump device comprising: the motor according to claim 9; and an impeller that is rotationally driven by said motor.

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