WO2024047863A1

WO2024047863A1 - Electric motor, air conditioner, and control board

Info

Publication number: WO2024047863A1
Application number: PCT/JP2022/033111
Authority: WO
Inventors: 隼一郎尾屋
Original assignee: 三菱電機株式会社
Priority date: 2022-09-02
Filing date: 2022-09-02
Publication date: 2024-03-07

Abstract

This electric motor (1) comprises a stator, a rotor, and a built-in board (11) having an inverter (81) that supplies current to the stator, where the inverter (81) has upper arm power transistors (81A to 81C) and lower arm power transistors (81D to 81F), and between the upper arm and the lower arm, the power transistors of the arm with the higher number of switchings are distributed and arranged on a first surface of the built-in board (11) and a second surface facing the first surface.

Description

Electric motor, air conditioner, and control board

The present disclosure relates to an electric motor equipped with an inverter, an air conditioner, and a control board.

In recent years, in order to save energy or improve the heating capacity of air conditioners, there has been a demand for higher output fan motors (fan electric motors) for air conditioners. Additionally, there is a demand for downsizing of fan motors in order to secure air passages. If the fan motor is made to have a high output and is made smaller, the temperature of the control board containing the inverter tends to rise. For this reason, it is desired to suppress the temperature rise of the control board containing the inverter.

The electric motor described in Patent Document 1 is configured integrally with a control board on which an inverter is mounted. In this motor, in order to improve heat dissipation, some of the power relays and switching elements and the remaining parts are mounted on different surfaces of the control board.

JP2020-195236A

However, in the technique disclosed in Patent Document 1, components are arranged on the control board without considering the operation of the components, so components with a large temperature increase are concentrated on one side of the control board. In this case, there is a problem that the amount of suppression of the temperature rise of the control board becomes small.

The present disclosure has been made in view of the above, and an object of the present disclosure is to obtain an electric motor that can greatly suppress the temperature rise of a control board.

In order to solve the above-mentioned problems and achieve the objects, the electric motor of the present disclosure includes a stator, a rotor, and a control board having an inverter circuit that supplies current to the stator. The inverter circuit includes a plurality of power transistors in an upper arm and a plurality of power transistors in a lower arm. The power transistors of the upper arm and the lower arm that undergo more switching are disposed in a distributed manner on a first surface of the control board and a second surface opposite to the first surface.

The electric motor according to the present disclosure has the effect of greatly suppressing the temperature rise of the control board.

A diagram showing a configuration example of an electric motor according to Embodiment 1. A diagram showing a circuit configuration of a built-in board included in the electric motor according to Embodiment 1. A diagram for explaining an example of switching performed by the electric motor according to the first embodiment A diagram showing the arrangement positions of power transistors arranged on the built-in board of the electric motor according to Embodiment 1. 1 is a sectional view schematically showing a first internal configuration example of the electric motor according to the first embodiment; FIG. A sectional view schematically showing a second internal configuration example of the electric motor according to the first embodiment. A diagram schematically showing a first arrangement example of power transistors on the built-in substrate according to the first embodiment. A diagram schematically showing a second arrangement example of power transistors on the built-in substrate according to the first embodiment. Cross-sectional diagram schematically showing the internal configuration of a comparative example electric motor Schematic diagram of an air conditioner according to Embodiment 2

Below, an electric motor, an air conditioner, and a control board according to an embodiment of the present disclosure will be described in detail based on the drawings.

Embodiment 1.
FIG. 1 is a diagram showing a configuration example of an electric motor according to a first embodiment. In the first embodiment, a case will be described in which the electric motor 1 is a three-phase electric motor, but the electric motor 1 of the first embodiment is not limited to a three-phase electric motor.

The electric motor 1 is a brushless DC (Direct Current) motor. In FIG. 1, in order to explain the configuration of the electric motor 1, a part of the structure is shown in cross section. Although FIG. 1 shows a radial gap type brushless DC motor, the electric motor 1 of the first embodiment is not limited to the radial gap type brushless DC motor.

The electric motor 1 includes a rotor 30, a stator 20, a built-in board 11 that is a control board, and a molded resin 12. A rotating shaft 31 is inserted into the rotor 30 . The stator 20 is provided on the outer periphery of the rotor 30. The built-in board 11 has a board circuit that is a circuit that controls the drive of the rotor 30.

The stator 20, the built-in substrate 11, and the molded resin 12 are fixed by the molded stator 10. The molded stator 10 is formed by integrally molding the stator 20 and the built-in substrate 11 (insert molding so that they are integrated). That is, the stator 20 and the built-in board 11 are fixed by the molded stator 10 so as to be integrated. Moreover, a recessed portion formed to accommodate the rotor 30 is provided inside the molded stator 10. Note that the stator 20 and the built-in substrate 11 may be integrally molded separately. In this case, the integrally molded stator 20 and the integrally molded built-in substrate 11 are joined.

The stator 20 includes a plurality of stator cores 21 , an insulator 23 integrally molded with the stator core 21 , and a winding group 22 . The stator core 21 is configured by laminating electromagnetic steel sheets. Insulator 23 insulates stator core 21 and winding group 22 .

In the electric motor 1, the stator 20 is configured by winding the windings of the winding group 22 around each slot of the stator core 21, which is integrally molded with the insulator 23. Each winding in the winding group 22 is made of copper, aluminum, or the like.

An output side bearing 33 that rotatably supports the rotating shaft 31 is provided at one end of the rotating shaft 31. The other end of the rotating shaft 31 is provided with a non-output side bearing 34 that rotatably supports the rotating shaft 31.

The non-output side bearing 34 is covered with a conductive bracket 60. In the bracket 60 , a press-fitting portion 61 of the bracket 60 is fitted into the inner peripheral portion of the molded stator 10 so as to close an opening of a recess provided in the molded stator 10 . Further, the outer ring of the non-output side bearing 34 is fitted inside the bracket 60.

The built-in board 11 includes a circuit including a control section 70 described later and a magnetic sensor 50 that detects the position of the rotor 30.

The built-in board 11 is arranged perpendicularly to the axial direction of the rotating shaft 31 between the output side bearing 33 and the stator 20 and is fixed to the insulator 23. The built-in board 11 is provided with a lead outlet 14 from which a lead wire 13 connected to a higher-level system (for example, a board on the side of an air conditioner unit) is drawn out. The upper system is a system in which the electric motor 1 is mounted. The lead wire 13 is connected to, for example, a board on the unit side of the air conditioner (such as an indoor unit board 211 to be described later). Furthermore, passive components such as an operational amplifier, a comparator, a regulator, a diode, a resistor, a capacitor, an inductor, and a fuse are arranged on the built-in board 11.

The shape of the built-in board 11 is, for example, a disk shape with a through hole formed in the center. Note that the built-in board 11 may have a shape other than a disk shape, such as a semicircular shape. The rotating shaft 31 is passed through the through hole provided in the built-in board 11 . Built-in board 11 is arranged inside electric motor 1 so that its top and bottom surfaces are perpendicular to the axial direction of rotating shaft 31 .

A rotor insulator 32, which is an annular member, is arranged on the outer periphery of the rotating shaft 31. The rotor 30 has a magnet 40 placed inside the molded stator 10. The magnet 40 is disposed on the outer peripheral side of the rotating shaft 31 at a position facing the stator core 21. The magnet 40 is composed of a cylindrical permanent magnet. The magnet 40 is fixed to the rotating shaft 31.

The magnet 40 is manufactured by injection molding a bonded magnet composed of a ferrite magnet or a rare earth magnet (samarium iron nitrogen, neodymium, etc.) mixed with a thermoplastic resin material. A magnet is incorporated in a mold for injection molding the magnet 40, and the magnet 40 is molded while being oriented. Note that the magnet 40 may be a sintered magnet.

The magnet 40 has, in the axial direction of the rotating shaft 31, a sensor magnet portion that is a portion close to the magnetic sensor 50, and a main magnet portion that is a portion other than the sensor magnet portion. The sensor magnet section allows the magnetic sensor 50 to detect the position of the rotor 30. The main magnet section generates a rotational force in the rotor 30 according to the magnetic flux generated by the winding group 22.

In the magnet 40, the outer diameter of the built-in board 11 on the magnetic sensor 50 side is smaller than the other outer diameter portions. That is, in the magnet 40, the outer diameter of the sensor magnet portion is smaller than the outer diameter of the main magnet portion. The shape of the magnet 40 allows magnetic flux to easily flow into the magnetic sensor 50 mounted on the built-in board 11. The magnetic sensor 50 is arranged at a position far from the winding group 22, that is, at a position close to the rotating shaft 31, in order to minimize the influence of the magnetic flux generated from the winding group 22 of the stator 20.

Although FIG. 1 shows a case where the main magnet section and the sensor magnet section are composed of one magnet 40, the main magnet section and the sensor magnet section may be composed of separate magnets. .

The magnetic sensor 50 may be configured using a Hall IC whose output signal is a digital signal, or may be configured using a Hall element whose output signal is an analog signal. That is, the magnetic sensor 50 may be of a type that detects the position of the rotor 30 using a Hall IC, or may be of a type that detects the position of the rotor 30 using a Hall element.

Further, the Hall IC may be a Hall IC (first method Hall IC) that detects the position of the rotor 30 using a first method described later, or a Hall IC that detects the position of the rotor 30 using a second method described later. It may be a Hall IC (second type Hall IC) that detects.

In the first type Hall IC, the sensor section and the amplification section are constructed from separate semiconductor chips. In this first type Hall IC, the sensor section is made of a semiconductor other than silicon, and the amplification section is made of silicon. Hereinafter, the first type Hall IC will be referred to as a non-silicon type Hall IC. In the second type Hall IC, the sensor section and the amplification section are constructed from one silicon semiconductor chip.

Since a non-silicon Hall IC has two built-in chips, the sensor section is arranged so that the center position of the sensor section is different from the center of the IC body. A non-silicon semiconductor such as indium antimonide (InSb) is used for the sensor portion of a non-silicon Hall IC. This non-silicon semiconductor has advantages over silicon semiconductors, such as higher sensitivity and smaller offset due to stress strain.

Next, the circuit configuration of the built-in board 11 shown in FIG. 1 will be explained. FIG. 2 is a diagram showing a circuit configuration of a built-in board included in the electric motor according to the first embodiment. FIG. 2 shows the built-in board 11, the winding group 22, and the magnetic sensor 50.

The built-in board 11 includes an overcurrent detection resistor 75 and a control section 70.

The control unit 70 is connected to the host system, the gate drive circuit 82, the ground 79A, and the magnetic sensor 50. Further, the control unit 70 is connected to a low voltage power source 78 via a connection point 48. Further, the control unit 70 is connected to a ground 79C via a connection point 41, a connection point 42, and an overcurrent detection resistor 75.

The gate drive circuit 82 is connected to the low voltage power supply 78 via the connection point 48 and to the high voltage power supply 77 via the connection point 47. Low voltage power supply 78 outputs a lower voltage than high voltage power supply 77. High voltage power supply 77 is a bus power supply.

Further, the gate drive circuit 82 is connected to the inverter 81. Further, the gate drive circuit 82 is connected to the protection circuit 83 and the ground 79B via the connection point 43.

The protection circuit 83 is connected to the connection point 41 and the connection point 43. That is, the protection circuit 83 is connected to the ground 79C via the connection point 41, the connection point 42, and the overcurrent detection resistor 75. Further, the protection circuit 83 is connected to the ground 79B via the connection point 43.

The inverter 81 is connected to the winding group 22 of the stator 20 and supplies current to the winding group 22 of the stator 20. Inverter 81 is also connected to ground 79C via connection point 42 and overcurrent detection resistor 75. Grounds 79A to 79C are common grounds having the same potential.

The inverter 81 includes six power transistors 81A to 81F. In the inverter 81, six power transistors 81A to 81F are separately configured. That is, the six power transistors 81A to 81F are each configured as separate components (chips).

The gate drive circuit 82 may be composed of one IC, or may be composed of three separate three-phase ICs. Further, the gate drive circuit 82 and the control section 70 may be configured by one IC. Further, the control unit 70 may be configured with one dedicated IC (control IC), or may be configured with a microcomputer (hereinafter referred to as a microcomputer).

The power transistors 81A to 81F are configured using superjunction MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), planar MOSFETs, IGBTs (Insulated Gate Bipolar Transistors), etc. Ru. Since a large current flows through the power transistors 81A to 81F, a large amount of heat is generated, and heat dissipation is desired.

In the first embodiment, a case will be described in which the magnetic sensor 50 detects the magnetic pole position of the rotor 30 corresponding to the magnetic flux position, and the built-in board 11 controls the electric motor 1 based on the magnetic pole position. Note that the built-in board 11 may perform sensorless control of the electric motor 1 while estimating the magnetic pole position from the current flowing through the winding group 22 and the voltage applied to and generated by the winding group 22. Further, the built-in board 11 may amplify a current signal obtained by using a shunt resistor and a current sensor with an operational amplifier or the like for current detection. Further, the built-in board 11 may use a comparator to generate a signal from this current signal to the control unit 70 for overcurrent protection.

In the built-in board 11, the voltage (for example, 15V) that drives the gates of the power transistors 81A to 81F may be different from the microcomputer power supply voltage (for example, 5V) that is the voltage that drives the control unit 70 such as a microcomputer. In this case, the electric motor 1 uses a regulator to generate another power source from one power source supplied from the outside. For example, a 15V power is supplied to the built-in board 11 from the outside, and the regulator generates a 5V power and supplies it to the built-in board 11. This regulator may be built into the gate drive circuit 82.

The inverter 81 converts the input DC voltage into a three-phase AC voltage consisting of U-phase, V-phase, and W-phase, and supplies it to the winding group 22 of the stator 20. Power transistor 81A is a U-phase upper arm power transistor, power transistor 81B is a V-phase upper arm power transistor, and power transistor 81C is a W-phase upper arm power transistor. Power transistor 81D is a U-phase lower arm power transistor, power transistor 81E is a V-phase lower arm power transistor, and power transistor 81F is a W-phase lower arm power transistor.

That is, the power transistor 81A is a U-phase upper arm power transistor, the power transistor 81B is a V-phase upper arm power transistor, and the power transistor 81C is a W-phase upper arm power transistor. Further, the power transistor 81D is a lower arm power transistor of the U phase, the power transistor 81E is a lower arm power transistor of the V phase, and the power transistor 81F is a lower arm power transistor of the W phase.

In this way, the inverter 81 has a plurality of power transistors in the upper arm and a plurality of power transistors in the lower arm. In Embodiment 1, the power transistor in the upper arm and the lower arm that switches more frequently is connected to the upper surface (first surface) of the built-in substrate 11 and the bottom surface (second surface) opposite to the first surface. are distributed and located. Further, in the first embodiment, the power transistor of the upper arm and the lower arm, which has a smaller switching frequency, is arranged on the upper surface of the built-in substrate 11.

The electric motor 1 includes a U-phase winding 22U, a V-phase winding 22V, and a W-phase winding 22W as windings included in the winding group 22. U-phase winding 22U is connected to

power transistors

81A and 81D. The V-phase winding 22V is connected to

power transistors

81B and 81E. W-phase winding 22W is connected to

power transistors

81C and 81F.

The gate drive circuit 82 controls on and off of the power transistors 81A to 81F according to the switching signal received from the control unit 70.

Three magnetic sensors 50 are arranged around the winding group 22. The three magnetic sensors 50 each output a magnetic pole position signal corresponding to the position of the rotor 30 to the control unit 70. The electric motor 1, which is a brushless DC motor, obtains rotational power by switching six (in the case of three phases) power transistors 81A to 81F at appropriate timings according to the magnetic pole position of the rotor 30. The switching signal in this case is generated by the control unit 70.

Further, when at least one of the inverter 81 and the gate drive circuit 82 becomes high temperature, the protection circuit 83 turns off all power transistors 81A to 81F of the inverter 81 to prevent element destruction due to the high temperature.

The overcurrent detection resistor 75 is connected to the lower arm switches included in the power transistors 81D to 81F. The protection circuit 83 monitors the voltage of the overcurrent detection resistor 75 and turns off the power transistors 81A to 81F when the voltage of the overcurrent detection resistor 75 exceeds a specific value, thereby preventing overcurrent from flowing to the winding group 22. Prevents current from flowing and provides overcurrent protection. Note that the overcurrent detection section may be built into the control section 70 or the gate drive circuit 82.

Note that a temperature sensing element (not shown) may be provided on the built-in substrate 11 or the like. In this case, when the control unit 70 receives a signal indicating an abnormal temperature from the temperature sensing element, it forcibly turns off the power transistors 81A to 81F, thereby realizing overheat protection.

The control unit 70 generates a switching signal that controls turning on and off of the power transistors 81A to 81F at a specific frequency (carrier frequency) in accordance with the speed command signal received from the host system.

The control unit 70 performs pulse width modulation (PWM) control on the power transistors 81A to 81F by outputting a switching signal to the gate drive circuit 82. The control unit 70 estimates the magnetic pole position of the rotor 30 based on the magnetic pole position signal input from the magnetic sensor 50, and calculates the rotation speed of the rotor 30 from the estimated magnetic pole position. The control unit 70 outputs a rotation speed signal indicating the calculated rotation speed to the host system.

The electric motor 1, which is a brushless DC motor, obtains rotational power by switching six power transistors 81A to 81F at appropriate timing in the case of a three-phase motor, depending on the magnetic pole position of the magnet 40 of the rotor 30. A switching signal used for this switching is generated by the control section 70. The operating principle of this electric motor 1 will be explained.

In the electric motor 1, the control unit 70 estimates the magnetic pole position of the rotor 30 based on the magnetic pole position signal from the magnetic sensor 50 or the current value of the current flowing through the winding group 22. Control unit 70 generates switching signals for switching power transistors 81A to 81F according to the magnetic pole position of rotor 30 and a speed command signal output from a host system. Gate drive circuit 82 switches power transistors 81A to 81F on and off according to a switching signal generated by control section 70.

The energization methods used by the electric motor 1 include 120° energization control, 150° energization control, and sine wave energization control.

For example, in the 120° energization control, the switching timing between on and off of the six power transistors 81A to 81F is the same as each rise and fall of the detection signal from the three Hall ICs. Therefore, in the 120° energization control, the control section 70 can be configured with a combinational circuit that does not require a clock.

On the other hand, in the case of control that requires estimation of the magnetic pole position, such as 150° energization control, sine wave energization control, phase control, and sensorless control, the control unit 70 is configured with a complicated digital circuit including a clock. In estimating the magnetic pole position, for example, the timing between each rise and fall of the detection signal from the three Hall ICs is precisely estimated.

Sensorless control is control that does not use the magnetic sensor 50. In sensorless control, control is performed by estimating the magnetic pole position from the current value detected by a current detection resistor, current detection transformer, etc. In sensorless control, a signal detected by a current detection resistor, a current detection transformer, or the like may be amplified using an operational amplifier or the like, if necessary.

As described above, the control unit 70 adjusts the voltage applied to the winding group 22 by PWM control of the power transistors 81A to 81F. In order to reduce loss due to switching of the inverter 81, the electric motor 1 may switch only one side of the upper and lower arms.

Here, switching by the electric motor 1 will be explained. FIG. 3 is a diagram for explaining an example of switching performed by the electric motor according to the first embodiment. FIG. 3 shows gate signals (switching signals) to power transistors 81A to 81F. The inverter 81 of the first embodiment executes control in which the number of times of switching is different between the upper arm and the lower arm.

The gate signal to the power transistor 81A, which is the U-phase upper arm power transistor, is the U-phase upper gate signal 93A. The gate signal to the power transistor 81B, which is the V-phase upper arm power transistor, is the V-phase upper gate signal 93B. The gate signal to the power transistor 81C, which is the W-phase upper arm power transistor, is the W-phase upper gate signal 93C.

Further, the gate signal to the power transistor 81D, which is the U-phase lower arm power transistor, is the U-phase lower gate signal 93D. The gate signal to the power transistor 81E, which is the V-phase lower arm power transistor, is the V-phase lower gate signal 93E. The gate signal to the power transistor 81F, which is the W-phase lower arm power transistor, is the W-phase lower gate signal 93F.

FIG. 3 shows a timing chart of the gate signals of the power transistors 81A to 81F when the upper arm switches more times in the specific period T1 than the lower arm (in the case of upper arm switching).

When the gate signal is High, the power transistor is turned on, and when the gate signal is Low, the power transistor is turned off. In the case of the timing chart shown in FIG. 3, the upper arm switches at a shorter cycle than the lower arm. The control unit 70 controls the motor 1 by changing the voltage applied to the winding group 22 by changing the switching duty of the upper arm.

Hereinafter, the configuration of the electric motor 1 will be described using as an example a case where the upper arm switches more times in the specific period T1 than the lower arm (in the case of upper arm switching). Note that the electric motor 1 of the first embodiment can be applied to the case of lower arm switching as well as to the case of upper arm switching.

FIG. 4 is a diagram showing the arrangement positions of power transistors arranged on the built-in board of the electric motor according to the first embodiment. FIG. 4 schematically shows the surface of the built-in board 11 on the opposite side to the stator (the upper surface that is the surface not facing the stator 20). Note that in FIG. 4, illustration of a through hole (a hole through which the rotating shaft 31 passes) formed in the built-in board 11 is omitted.

Regarding the built-in board 11, one of the six power transistors 81A to 81F is arranged on the stator side surface (bottom surface) of the built-in board 11, and the remaining five are arranged on the anti-stator side surface (top surface). be done. FIG. 4 shows a case in which the upper arm power transistor 81B is arranged on the stator side surface of the built-in substrate 11, and the remaining

power transistors

81A, 81C to 81F are arranged on the anti-stator side surface.

In this way, the power transistors of the arm that undergoes more switching (power transistors whose temperature is more likely to rise) are distributed and arranged on the stator side surface and the anti-stator side surface of the built-in substrate 11. Thereby, the built-in substrate 11 can avoid heat concentration on the built-in substrate 11, and it becomes possible to suppress the temperature rise of the power transistors 81A to 81F. Therefore, the built-in board 11 can greatly suppress the temperature rise of the built-in board 11.

When three upper arm power transistors are arranged side by side in a specific direction on the built-in board 11, the power transistor arranged in the center among the three upper arm power transistors is arranged on the stator side surface, so that the built-in board The effect of suppressing heat concentration in step 11 becomes greater.

For the built-in board 11, pairs of upper and lower arms of each phase are arranged in the radial direction (direction from the center toward the outer periphery) when the built-in board 11 is viewed from the top. That is, when the built-in board 11 is viewed from above, a pair of U-phase upper and lower arms are arranged along the radial direction (first radial direction), and a pair of U-phase upper and lower arms are arranged along the radial direction (second radial direction). A pair of V-phase upper and lower arms is arranged along the radial direction (radial direction), and a W-phase upper and lower arm pair is arranged along the radial direction (third radial direction).

Further, for the built-in board 11, when the built-in board 11 is viewed from above, three-phase upper arms are arranged side by side in the circumferential direction (first circumferential direction) with respect to the axial direction of the rotating shaft 31, and Three-phase lower arms are arranged side by side (in the second circumferential direction). Thereby, on the upper surface of the built-in substrate 11, the upper arm power transistors and the lower arm power transistors are arranged in two rows along the circumferential direction. The circumferential direction (first circumferential direction and second circumferential direction) of the built-in substrate 11 is a direction along the outer periphery of the built-in substrate 11 .

FIG. 4 shows a case where power transistors 81A to 81C are arranged along the circumferential direction when the built-in board 11 is viewed from the top. Further, FIG. 4 shows a case where power transistors 81D to 81F are arranged along the circumferential direction when the built-in board 11 is viewed from the top.

In the first embodiment, for example, the

power transistors

81A and 81C are arranged on the top surface of the built-in substrate 11, and the power transistor 81B is arranged on the bottom surface of the built-in substrate 11. Further, power transistors 81D to 81F are arranged on the upper surface of the built-in substrate 11.

This arrangement of power transistors 81A to 81F facilitates pattern wiring for power transistors 81A to 81F. In this case, the power transistor of the upper arm that switches more frequently is arranged on the outer circumferential side, and the power transistor of the lower arm that switches more frequently is arranged on the inner circumferential side.

That is, in the built-in substrate 11, the power transistor of the arm that switches more often is arranged closer to the outer periphery than the power transistor of the arm that switches more often. Then, at least one of the power transistors that undergoes more switching is arranged on the bottom surface of the built-in substrate 11.

In this way, the power transistor (here, the upper arm power transistor) that has a larger switching frequency is arranged on the outer circumferential side, and one of the upper arm power transistors (here, the power transistor 81B) is placed on the built-in board 11. It is placed on the stator side surface.

The temperature of the power transistor 81B placed on the stator side surface tends to rise due to the influence of the winding group 22, but since the power transistor 81B is placed closer to the outer periphery than the lower arm power transistor, Heat is also easily radiated from the sides of the electric motor 1. In this way, the heat from the power transistor 81B disposed on the stator side surface is also easily radiated from the side surface of the motor 1, so that the heat dissipation of the built-in board 11 is improved. In other words, by arranging the power transistor that switches more frequently on the outer circumferential side, the heat generated by the power transistor that switches more often can be easily dissipated from the side of the motor 1, and the effect of suppressing temperature rise is greater. Become.

Note that when the arm with the greater number of switching is the lower arm, the power transistor of the lower arm is arranged along the circumferential direction on the outer circumferential side than the power transistor of the upper arm. At least one of the power transistors 81D to 81F (for example, the power transistor 81E) is arranged on the bottom surface of the built-in substrate 11.

FIG. 5 is a cross-sectional view schematically showing a first internal configuration example of the electric motor according to the first embodiment. Note that in FIG. 5, illustration of power transistors 81D to 81F, which are lower arm power transistors, is omitted. Although FIG. 5 shows a case where the power transistor 81A and the power transistor 81B are arranged at opposing positions with the built-in board 11 in between, as shown in FIG. It may be arranged at a position that does not face 81A and 81C.

For example, the

power transistors

81A and 81C of the power transistors 81A to 81C, which are upper arm power transistors, are arranged on the opposite surface of the built-in substrate 11 with respect to the winding group 22. That is, the

power transistors

81A and 81C are arranged on the side opposite to the stator of the built-in substrate 11. In other words, when the stator core 21 and the winding group 22 are arranged at positions facing the bottom surface of the built-in board 11, the

power transistors

81A and 81C are placed on the top surface of the built-in board 11, which is the surface opposite to the bottom surface. It is located in This makes the

power transistors

81A and 81C less susceptible to the effects of heat generated from the winding group 22. Therefore, the built-in substrate 11 can suppress the temperature rise of the

power transistors

81A and 81C.

Further, of the power transistors 81A to 81C, which are upper arm power transistors, the power transistor 81B is arranged on the stator side of the built-in substrate 11. In other words, the power transistor 81B is arranged on the bottom surface of the built-in substrate 11. This makes power transistor 81B less susceptible to the effects of heat emitted from

power transistors

81A and 81C. Therefore, the built-in substrate 11 can suppress the temperature rise of the power transistor 81B.

Note that the power transistor 81A may be arranged on the stator side of the built-in substrate 11, and the

power transistors

81B and 81C may be arranged on the side opposite to the stator of the built-in substrate 11. Further, the power transistor 81C may be arranged on the stator side of the built-in substrate 11, and the

power transistors

81A and 81B may be arranged on the side opposite to the stator of the built-in substrate 11.

Furthermore, two power transistors among the power transistors 81A to 81C may be arranged on the stator side of the built-in substrate 11.

The power transistors 81D to 81F are arranged on the side opposite to the stator of the built-in substrate 11. In this way, the number of power transistors arranged on the side opposite to the stator is greater than the number of power transistors arranged on the stator side. In the built-in board 11, the anti-stator side has better heat dissipation than the stator side, so the heat dissipation improves when more power transistors are arranged on the anti-stator side.

FIG. 6 is a cross-sectional view schematically showing a second internal configuration example of the electric motor according to the first embodiment. Note that in FIG. 6, illustration of power transistors 81D to 81F, which are lower arm power transistors, is omitted. Although FIG. 6 shows a case where the power transistor 81A and the power transistor 81B are arranged at opposite positions with the built-in substrate 11 in between, as shown in FIG. It may be arranged at a position that does not face 81A and 81C.

FIG. 6 shows a case where the electric motor 1 is equipped with a heat sink 5. The heat sink 5 dissipates heat generated by the electric motor 1. The other configuration of the electric motor 1 including the heat sink 5 is the same as the configuration of the electric motor 1 shown in FIG. For example, in the electric motor 1, the heat sink 5 may be provided on the side opposite to the stator with respect to the built-in board 11. In this case, the heat sink 5 is placed on the side opposite to the stator of the built-in board 11 with the molded resin 12 interposed therebetween. The heat sink 5 is integrally molded with the built-in substrate 11 using a mold resin 12, or is attached after the mold resin 12 and the built-in substrate 11 are integrally molded. In this case, a heat radiating member is disposed between the heat sink 5 and the mold resin 12 in order to reduce the contact thermal resistance between the heat sink 5 and the mold resin 12. Examples of the heat dissipation member are a heat conductive sheet, heat conductive grease, or a heat dissipation pad.

What are the heat dissipation patterns of the

power transistors

81A and 81C arranged on the anti-stator side (heat dissipation substrate pattern 2A described later) and the axial height of the bodies or heat dissipation tabs of the

power transistors

81A and 81C disposed on the anti-stator side? Although not uniformly, the side of the built-in substrate 11 opposite to the stator is filled with the molding resin 12 without any gaps. Therefore, the

power transistors

81A, 81C on the anti-stator side and the heat sink 5 can be joined with the mold resin 12 filled without any gaps. Therefore, it is possible to suppress the heat conduction in the heat sink 5 from being extremely reduced due to gaps or the like.

If the mold resin 12 is not integrally molded on the built-in substrate 11, a heat radiation pad is arranged between the heat sink 5 and the

power transistors

81A, 81C or the heat radiation pattern. In this case, if the heights of the bodies of the

power transistors

81A, 81C and the heights of the heat radiation patterns are not the same, it becomes difficult to fill the space between the heat sink 5 and the built-in substrate 11 with heat radiation pads without any gaps. On the other hand, in the first embodiment, since the mold resin 12 is integrally molded on the built-in substrate 11, it becomes possible to fill the space between the heat sink 5 and the built-in substrate 11 with the mold resin 12 without any gap.

Note that a heat radiation tab (heat radiation tab 85T described later) of the power transistor is also connected to a heat radiation pattern (heat radiation substrate pattern 2B described later) of the power transistor arranged on the stator side. Then, the mold resin 12 is placed so as to cover the power transistor having the heat dissipation tab 85T.

In this way, in the electric motor 1, at least one power transistor of the upper arm and one of the lower arm power transistors, which is switched more often, is arranged on both sides of the built-in substrate 11. That is, in the electric motor 1, the power transistors of the arm that undergoes more switching are distributed and arranged on the top and bottom surfaces of the built-in substrate 11.

In the electric motor 1, the arm that has been switched more often has a larger temperature rise than the arm that has been switched less often. Therefore, the power transistors of the arm that undergoes more switching are arranged in a distributed manner on the top and bottom surfaces of the built-in substrate 11, thereby increasing the effect of suppressing temperature rise.

Note that through holes may be formed in the built-in substrate 11 in order to improve heat dissipation of the power transistors arranged on the stator side. Here, the configuration of the built-in board 11 when through holes are formed will be described.

FIG. 7 is a diagram schematically showing a first example of arrangement of power transistors on the built-in substrate according to the first embodiment. FIG. 7 shows a cross-sectional view of the built-in substrate 11 when the through hole 4 is formed.

A heat dissipation substrate pattern 2A is arranged on the top surface of the built-in substrate 11 (surface opposite to the stator), and a heat dissipation substrate pattern 2B is disposed on the bottom surface of the built-in substrate 11 (surface on the stator side). The heat

dissipation substrate patterns

2A and 2B are patterns that diffuse heat generated in the built-in substrate 11. The heat dissipation substrate pattern 2A is the first heat dissipation substrate pattern, and the heat dissipation substrate pattern 2B is the second heat dissipation substrate pattern.

Furthermore, the power transistor 81B arranged on the bottom side of the built-in substrate 11 has a heat dissipation tab 85T for improving heat dissipation. The heat dissipation tab 85T dissipates heat generated by the power transistor 81B.

The heat radiation substrate pattern 2B is connected to the heat radiation tab 85T. The heat radiation substrate pattern 2B connected to the heat radiation tab 85T is connected to the heat radiation substrate pattern 2A on the anti-stator side via the through hole 4. The through hole 4 is a hole that penetrates the built-in board 11. A member having a thermal conductivity higher than a specific value may be embedded in the through hole 4. For example, a member having higher thermal conductivity than that of the built-in substrate 11 may be embedded in the through hole 4 .

With such a configuration of the built-in board 11, the power transistor 81B releases heat via the heat radiation tab 85T, the heat radiation board pattern 2B, the through hole 4, and the heat radiation board pattern 2A.

Note that the

power transistors

81A, 81C, 81D to 81F arranged on the upper surface side of the built-in substrate 11 may have a heat radiation tab 85T. Further, the built-in board 11 does not need to be provided with the heat dissipation tab 85T. In this case, power transistor 81B is not connected to heat radiation tab 85T.

FIG. 8 is a diagram schematically showing a second arrangement example of power transistors on the built-in substrate according to the first embodiment. FIG. 8 shows a cross-sectional view of the built-in substrate 11 when the through hole 4 is formed.

Even when the heat dissipation tab 85T is not arranged on the built-in board 11, the heat dissipation board pattern 2A is arranged on the top surface (the surface opposite to the stator) of the built-in board 11, and A heat dissipation substrate pattern 2B is arranged.

If the heat dissipation tab 85T is not arranged on the built-in substrate 11, the lower part of the package of the power transistor 81B, which becomes hot, is connected to the heat dissipation substrate pattern 2B. Then, the heat dissipation substrate pattern 2B connected to the lower part of the package of the power transistor 81B is connected to the heat dissipation substrate pattern 2A on the side opposite to the stator via the through hole 4. With this configuration, the power transistor 81B releases heat via the heat dissipation substrate pattern 2B, the through hole 4, and the heat dissipation substrate pattern 2A.

Here, the configuration of the electric motor of the comparative example will be explained. FIG. 9 is a cross-sectional view schematically showing the internal configuration of a motor according to a comparative example. In the electric motor 1X of the comparative example, power transistors 81A to 81F are all arranged on the same surface (upper surface) on the built-in substrate 11X. That is, in the electric motor 1X of the comparative example, the power transistors 81A to 81C are arranged on the opposite surface of the built-in board 11X with respect to the winding group 22. Note that in FIG. 9, illustration of the power transistors 81D to 81F is omitted.

In the motor 1 of the first embodiment, the

power transistors

81A and 81C of the power transistors 81A to 81C are arranged on the opposite surface of the built-in board 11 with respect to the winding group 22. Therefore, the built-in board 11 included in the electric motor 1 of the first embodiment can suppress the temperature rise more than the built-in board 11X included in the electric motor 1X of the comparative example. That is, in the built-in board 11 included in the electric motor 1 of the first embodiment, components with a large temperature rise are not arranged only on one surface of the built-in board 11, so that the amount of suppression of the temperature rise of the built-in board 11 is suppressed. growing.

As described above, in the electric motor 1 of the first embodiment, the power transistors of the upper arm and the lower arm, which have a higher number of switching operations, are distributed and arranged on the upper surface and the lower surface of the built-in substrate 11. Thereby, the electric motor 1 can greatly suppress the temperature rise of the built-in board 11, which is a control board.

Embodiment 2.
Next, Embodiment 2 will be described using FIG. 10. In the second embodiment, the electric motor 1 described in the first embodiment is applied to an air conditioner.

FIG. 10 is a schematic diagram of an air conditioner according to the second embodiment. An air conditioner 200 that is an air conditioner includes an indoor unit 210 and an outdoor unit 220 connected to the indoor unit 210. The indoor unit 210 is equipped with the electric motor 1, an indoor unit board 211, and an indoor unit blower (not shown). The outdoor unit 220 is equipped with an outdoor unit blower 223.

The outdoor unit blower 223 and the indoor unit blower each incorporate the electric motor 1 described in Embodiment 1 as a drive source. In particular, when the air conditioner 200 is for commercial use, high output and high heat dissipation performance are required, so the heat dissipation effect is increased by applying the electric motor 1 described in Embodiment 1.

In addition to the air conditioner 200, the electric motor 1 can be used by being installed in, for example, a ventilation fan, a home appliance, a machine tool, etc.

As described above, according to the second embodiment, the electric motor 1 described in the first embodiment is applied to the air conditioner 200, so that the temperature rise of the built-in board 11 can be greatly suppressed.

The configurations shown in the embodiments above are merely examples, and can be combined with other known techniques, or can be combined with other embodiments, within the scope of the gist. It is also possible to omit or change part of the configuration.

1, 1X electric motor, 2A, 2B heat dissipation board pattern, 4 through hole, 5 heat sink, 10 molded stator, 11, 11X built-in board, 12 molded resin, 13 lead wire, 14 lead outlet, 20 stator, 21 fixing Child core, 22 Winding group, 22U U phase winding, 22V V phase winding, 22W W phase winding, 23 Insulator, 30 Rotor, 31 Rotating shaft, 32 Rotor insulation section, 33 Output side bearing, 34 Reverse Output side bearing, 40 magnet, 41 to 43, 47, 48 connection point, 50 magnetic sensor, 60 bracket, 61 press-fit part, 70 control part, 75 overcurrent detection resistor, 77 high voltage power supply, 78 low voltage power supply, 79A to 79C ground , 81 inverter, 81A to 81F power transistor, 82 gate drive circuit, 83 protection circuit, 85T heat dissipation tab, 93A U phase upper gate signal, 93B V phase upper gate signal, 93C W phase upper gate signal, 93D U phase lower gate signal , 93E V-phase lower gate signal, 93F W-phase lower gate signal, 200 Air conditioner, 210 Indoor unit, 211 Indoor unit board, 220 Outdoor unit, 223 Outdoor unit blower.

Claims

a stator;
rotor and
a control board having an inverter circuit that supplies current to the stator;
Equipped with
The inverter circuit includes a plurality of power transistors in an upper arm and a plurality of power transistors in a lower arm,
The power transistors of the upper arm and the lower arm, which has a higher switching frequency, are arranged in a distributed manner on a first surface of the control board and a second surface opposite to the first surface. There is,
Electric motor.
The second surface is a surface on which the stator is arranged, and the number of power transistors arranged on the first surface is greater than the number of power transistors arranged on the second surface. There are many
The electric motor according to claim 1.
The control board is
A plurality of power transistors in the upper arm are arranged along a first circumferential direction when viewed from above the first surface of the control board, and a plurality of power transistors in the lower arm are arranged along a first circumferential direction when viewed from above the first surface of the control board. By being arranged along the second circumferential direction when viewed from above the first surface, the plurality of power transistors of the upper arm and the plurality of power transistors of the lower arm are arranged along the second circumferential direction when viewed from above the first surface. They are arranged in two rows along the circumferential direction when viewed from the surface of
The power transistor of the arm with the higher switching frequency is arranged on the first surface of the control board closer to the outer circumferential side than the power transistor of the arm with the lower switching frequency.
The electric motor according to claim 1 or 2.
The power transistor disposed on the second surface has a heat dissipation tab that dissipates heat generated in the power transistor,
A first heat dissipation board pattern, which is a pattern for diffusing heat generated in the control board, is disposed on the first surface of the control board,
A second heat dissipation board pattern, which is a pattern for diffusing heat generated in the control board, is disposed on the second surface of the control board,
The heat dissipation tab is connected to a second heat dissipation board pattern, and the first heat dissipation board pattern and the second heat dissipation board pattern are connected via a through hole penetrating the control board. has been,
The electric motor according to any one of claims 1 to 3.
A first heat dissipation board pattern, which is a pattern for diffusing heat generated in the control board, is disposed on the first surface of the control board,
A second heat dissipation board pattern, which is a pattern for diffusing heat generated in the control board, is disposed on the second surface of the control board,
The first heat dissipation board pattern and the second heat dissipation board pattern are connected via a through hole penetrating the control board.
The electric motor according to any one of claims 1 to 3.
It also has a heat sink to dissipate heat.
The control board is integrally molded using resin,
the heat sink is disposed on the first surface of the control board via the resin;
The electric motor according to any one of claims 1 to 5.
comprising the electric motor according to any one of claims 1 to 6,
Air conditioner.
an inverter circuit that supplies current to the stator of an electric motor including a stator and a rotor;
The inverter circuit includes a plurality of power transistors in an upper arm and a plurality of power transistors in a lower arm,
The power transistors of the upper arm and the lower arm, which has a higher switching frequency, are distributed and arranged on a first surface of the substrate and a second surface opposite to the first surface. ,
control board.