JP2011055703A - Brushless dc motor and electrical device including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact, light-weight and highly reliable brushless direct-current (DC) motor that is easy to assemble and wire, and an electrical device with the brushless DC motor mounted thereon. <P>SOLUTION: A brush-less DC motor includes a stator assembly having drive-coils for plural phases, a rotor assembly having a permanent magnet, and a built-in printed wired board (PWB) having a driving circuit for driving the drive coils. The driving circuit includes MOSFETs powering the drive coils, gate drivers controlling the MOSFETs, and a pre-driver supplying a PWM signal to the gate drivers. The PWB includes a power module formed by unifying the MOSFETs and the gate drivers with molding resin. The power module includes a setting section which sets electrical strength of the MOSFETs. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a brushless DC motor with a built-in drive circuit and an electric device equipped with the motor.

  A small brushless DC motor with a shaft output of about 20 to 50 W, which is used for blower fans of various home appliances such as room air conditioners, has a built-in driving device in which various electronic components are arranged on a printed wiring board. Things are common. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 3-270677

  FIG. 13 is a cross-sectional view of a conventional brushless DC motor. The stator mold assembly 103 is configured by winding a multiphase drive coil 121 around a stator core 120 in which electromagnetic steel plates are laminated, and integrally molding the whole with an unsaturated polyester resin. One end of the stator mold assembly 103 is covered with a metal bracket 104. A bearing holding portion is formed at the center portion of the bracket 104 and the other end portion of the stator mold assembly 103.

  On the other hand, the rotor assembly 119 is configured by providing a multi-pole permanent magnet 117 on the outer periphery of a rotor yoke 118 on which electromagnetic steel plates are laminated, and fixing the shaft 105 by a method such as press-fitting at the center, and is rotatable by a bearing 114. It is supported. The permanent magnet 117 is opposed to the inner peripheral portion of the stator core 120 via a predetermined gap.

  A printed wiring board 113 on which a drive circuit for driving the drive coil 121 is mounted is fixed to the stator mold assembly 103. The terminal of the drive coil 121 is connected to the printed wiring board 113 via the terminal pin 122. A MOSFET array 110, a pre-driver 112, and a large number of individual parts (not shown) are soldered and mounted on the printed wiring board 113, and a magnetic sensor 125 for detecting the magnetic pole position of the permanent magnet 117 is similarly soldered and mounted. Has been. Further, an insulating plate 115 is disposed between the printed wiring board 113 and the bracket 104 so as to be insulated from the bracket 104.

  FIG. 14 is a plan view of the printed wiring board assembly 107. A MOSFET array 110, a pre-driver 112, three gate drivers 111, and a large number of individual components 131 are mounted on the printed wiring board 113. Further, a lead wire assembly 102 for input / output connection is arranged. The individual component 131 is a resistor and a capacitor.

  The MOSFET array 110 has a configuration in which six MOSFETs are integrated, and drives the drive coil 121. Since this MOSFET has an avalanche resistance, there is a great reliability effect that it is not easily destroyed even if a pulsed overvoltage exceeding the breakdown voltage of this MOSFET, such as a surge voltage, is applied.

  However, on the other hand, in order to increase the electrical strength and improve the reliability of the MOSFET, the voltage change rate dV / dt of the drain-source voltage, the current change rate di / dt of the drain current, and the turn-on delay time td (On), turn-off delay time td (off), etc. must be set strictly. For this purpose, at least 4 to 6 individual components such as resistors, capacitors and diodes are required for each gate, and 4 × 6 to 6 × 6, that is, 24 to 36 individual components are required for driving a three-phase motor. I need it. If auxiliary parts are included, the total number may be about 100, making it difficult to reduce the size of the printed wiring board.

  In addition, there is a device in which a drive circuit is made into a monolithic IC by using an IGBT instead of a MOSFET as a switching element. For example, although there are some which are described in Patent Document 1 and the like, there is further provided a brushless DC motor which is small and light, can be easily mounted and wired, and has high reliability, and an electric device equipped with the same. It is desired.

  The brushless DC motor of the present invention is a brushless DC motor including a stator assembly having a plurality of phases of drive coils and a rotor assembly having permanent magnets, and includes a printed wiring board on which a drive circuit for driving the drive coils is mounted. ing.

  This drive circuit includes a MOSFET that supplies power to the drive coil, a gate driver that controls the MOSFET, and a pre-driver that supplies a PWM signal to the gate driver.

  The printed wiring board includes a power module in which a MOSFET and a gate driver are integrated with a mold resin material, and the power module includes a setting unit for setting the electrical strength of the MOSFET.

  With the above configuration, according to the present invention, it is possible to provide a brushless DC motor that is small and light, easy to mount and wire, and highly reliable, and an electric device equipped with the brushless DC motor.

  According to the configuration of the present invention, it is possible to provide a brushless DC motor that is small and light, easy to mount and wire, and highly reliable, and an electric device equipped with the brushless DC motor.

1 is an external view of a brushless DC motor according to Embodiment 1 of the present invention. Sectional view Circuit configuration diagram Cross section of the same power module Plan view of printed wiring board assembly Detailed circuit configuration diagram for one phase Explanatory drawing of the time chart which shows the relation between the input signal and output signal of the gate driver same as the above Explanatory drawing of the detailed time chart which expanded the part of the time t1 in FIG. FIG. 8 is a time chart showing the same relationship as in FIG. Explanatory diagram of detailed time chart when the threshold voltage of MOSFET is increased External view of electrical equipment in Embodiment 2 of the present invention Circuit configuration diagram Sectional view of a conventional brushless DC motor Plan view of printed wiring board assembly

  Hereinafter, the form for implementing this invention is demonstrated in a specific Example.

  FIG. 1 is an external view of a brushless DC motor 1 according to Embodiment 1 of the present invention. The stator mold assembly 3 is covered with a lid-like bracket 4 and the shaft 5 protrudes. The lead wire assembly 2 for input / output extends from the side surface of the stator mold assembly 3.

  FIG. 2 is a cross-sectional view of the brushless DC motor according to the first embodiment of the present invention. The stator mold assembly 3 is configured by winding a multiphase drive coil 21 around a stator core 20 in which electromagnetic steel plates are laminated, and integrally molding the whole with an unsaturated polyester resin. One end of the stator mold assembly 3 is covered with a metal bracket 4. A bearing holding portion is formed at the center portion of the bracket 4 and the other end portion of the stator mold assembly 3.

  On the other hand, the rotor assembly 19 is constructed by providing a multi-pole permanent magnet 17 on the outer periphery of a rotor yoke 18 laminated with electromagnetic steel plates, and fixing the shaft 5 by a method such as press-fitting at the center, and is rotatable by a bearing 14. It is supported. The permanent magnet 17 is opposed to the inner peripheral portion of the stator core 20 via a predetermined gap.

  A printed wiring board 13 on which a drive circuit for driving the drive coil 21 is mounted is fixed to the stator mold assembly 3. The terminal of the drive coil 21 is connected to the printed wiring board 13 via the terminal pin 22. A power module 10, a pre-driver 12, and individual parts (not shown) are soldered and mounted on the printed wiring board 13, and a magnetic sensor 25 for detecting the magnetic pole position of the permanent magnet 17 is similarly soldered and mounted. Yes. Further, an insulating plate 15 is disposed between the printed wiring board 13 and the bracket 4 so as to be insulated from the bracket 4.

  The power module 10 mounted on the printed wiring board 13 has a structure for radiating heat to the bracket 4 via the high thermal conductive resin material 16. As the high thermal conductivity resin material 16, a silicon resin having good thermal conductivity is used. This silicon-based resin has elasticity and can absorb variations in the distance between the power module 10 and the bracket 4.

  FIG. 3 is a circuit configuration diagram of the brushless DC motor 1 according to the first embodiment of the present invention. A high-voltage DC voltage Vdc from the high-voltage DC power supply 9, a control voltage Vcc from the control power supply 23, and a control signal voltage Vsp from the speed control signal 24 are input to the drive circuit 6, respectively. The output of the drive circuit 6 is supplied to a drive coil 21 that is three-phase star connected. A motor rotation signal FG is output from the drive circuit 6 and used for speed control.

  The drive circuit 6 receives the signals of the three magnetic sensors 25 for detecting the magnetic pole position of the rotor, the signals of the magnetic sensors 25 and the pre-driver 12 that generates the PWM signal, and the signals of the pre-driver 12 and the control signal of the MOSFET 8 Are composed of three gate drivers 11 and six MOSFETs 8 connected in a three-phase bridge. As the magnetic sensor 25, a Hall element or a Hall IC is generally used. The output current is detected by the current detection resistor 26 and fed back to the pre-driver 12.

  The three gate drivers 11 and the six MOSFETs 8 are integrated to constitute a power module 10. FIG. 4 is a cross-sectional view of the power module 10. The gate driver 11 and the MOSFET 8 are bonded and fixed to the frame 28, and between them and between the lead electrodes 27 are connected by a bonding wire 30. The entirety is integrally formed with an epoxy resin 29.

  FIG. 5 is a plan view of the printed wiring board assembly 7. The power module 10, the pre-driver 12, and the individual component 31 are mounted on the printed wiring board 13. Further, the lead wire assembly 2 for input / output connection is arranged. The individual parts 31 are resistors and capacitors.

  FIG. 6 is a detailed circuit configuration diagram of the brushless DC motor according to the first embodiment of the present invention, in which one phase of the entire circuit diagram shown in FIG. 3 is extracted. In the MOSFET 8 shown in FIG. 3, the MOSFET Q1 and the MOSFET Q2 are actually connected in series, and the high-voltage DC voltage Vdc is supplied. MOSFET Q1 includes a flywheel diode D1 and a gate capacitor C1 as parasitic elements. Similarly, the MOSFET Q2 includes a flywheel diode D2 and a gate capacitor C2 as parasitic elements.

  The gate driver 11 includes hysteresis comparators HS1, HS2, a level shift circuit LS1, resistors R1, R2, R3, R4, and output electronic switches SW1, SW2, SW3, SW4. The gate driver 11 receives the PWM signal generated by the pre-driver 12 as an input signal HIN and an input signal LIN, and supplies output signals HO and LO to the gates of the MOSFET Q1 and the MOSFET Q2.

  FIG. 7 is a time chart showing the relationship between the input signals HIN and LIN of the gate driver 11 and the output signals HO and LO. At time t <t1, since the input signals HIN and LIN are both at a low level, the upper output electronic switches SW1 and SW3 are turned off and the lower output electronic switches SW2 and SW4 are turned on. Accordingly, the output signals HO and LO are both kept at a low level, and the MOSFETs Q1 and Q2 are in an off state.

  Next, at time t = t1, the input signal HIN rises to a high level, and the input signal LIN remains at a low level. Accordingly, the output electronic switch SW1 is turned on, the output electronic switch SW2 is turned off, and the MOSFET Q1 is turned on when the output signal HO rises to a high level. MOSFET Q2 remains off. At this time, the charge stored in the boot capacitor C3 is supplied to the gate of the MOSFET Q1 via the resistor R1, but the output signal HO rises with a certain time constant. The MOSFET Q1 continues to turn off until the output signal HO reaches the threshold voltage Vth of the MOSFET Q1, and turns on when t = t10 when the threshold voltage Vth is reached. When the MOSFET Q1 is turned on, the high-voltage DC voltage Vdc is supplied to the drive coil 21.

  Next, at time t = t2, the input signal HIN falls to the low level, and the input signal LIN remains at the low level. Accordingly, the output electronic switch SW1 is turned off, the output electronic switch SW2 is turned on, and the output signal HO falls with a time constant determined by the resistor R2 and the gate capacitor C1 of the MOSFET Q1. The MOSFET Q1 continues to be turned on until the output signal HO falls below the threshold voltage Vth of the MOSFET Q1, and turns off when t = t20, which falls below the threshold voltage Vth.

  Next, at time t = t3, the input signal HIN remains at a low level, and the input signal LIN rises to a high level. As a result, the output electronic switch SW3 is turned on and SW4 is turned off. The output signal LO rises with a time constant determined by the capacitor C2 and the resistor R3. The MOSFET Q2 continues to turn off until the output signal LO reaches the threshold voltage Vth of the MOSFET Q2, and turns on when t = t30 when the threshold voltage Vth is reached.

  Next, at time t = t4, the input signal HIN remains at low level, and the input signal LIN falls to low level. Accordingly, the output electronic switch SW3 is turned off, the output electronic switch SW4 is turned on, and the output signal LO falls with a time constant determined by the resistor R4 and the gate capacitor C2 of the MOSFET Q2. The MOSFET Q2 continues to be turned on until the output signal LO falls below the threshold voltage Vth of the MOSFET Q2, and turns off when t = t40, which falls below the threshold voltage Vth.

  Next, when time t = t5, the state returns to the same state as the above-described time t = t1, and this series of operations is repeated.

FIG. 8 is a diagram in which a portion at time t1 in FIG. 7 is enlarged and a change in the drive coil terminal voltage VU is added. When the input signal HIN switches from the low level to the high level at time t = t1, the output signal HO starts to rise at t = t11 after the transmission time of the hysteresis comparator HS1, the level shift circuit LS1, and the output electronic switch SW1 has elapsed. (In FIG. 7, this transmission time is omitted.)
Next, the output signal HO reaches the threshold voltage Vth, and the MOSFET Q1 is turned on. In practice, however, the signal HO hardly changes at a voltage in the vicinity of Vth while the MOSFET Q1 itself is turned on. This is due to the fact that the gate-capacitance C1 of Q1 becomes very large (Miller effect) because the voltage between the drain and source of the MOSFET Q1 changes from OFF to ON. That is, the threshold voltage Vth is reached at time t = t12, the MOSFET Q1 starts to turn on, and the drive coil terminal voltage VU starts to rise. While the voltage VU is increasing, the signal HO does not change much due to the mirror effect. When the drive coil terminal voltage VU becomes substantially the high-voltage DC voltage Vdc at time t = t13, the influence of the mirror effect disappears and the signal HO starts to rise further. The voltage change rate dV / dt of the drive coil terminal voltage VU at this time increases as the time from t12 to t13 decreases.

  The voltage change rate dV / dt of the drive coil terminal voltage VU is determined by a time constant due to the feedback capacitance between the resistor R1 and the gate and drain of the MOSFET Q1. Accordingly, the voltage change rate dV / dt of the drive coil terminal voltage VU can be set by setting the feedback capacity between the resistor R1 or the gate Q-drain of the MOSFET Q1, but this voltage change rate dV is usually set by the easily set resistor R1. / Dt is set. For example, when a motor is used for home appliances, the resistance R1 is set so that the voltage change rate dV / dt is about 2 kV / μsec.

  In the above description, the MOSFET Q1 is switched from OFF to ON, but the voltage change rate dV / dt of the drive coil terminal voltage VU can be set similarly when Q1 is switched from ON to OFF. That is, dV / dt when Q1 is turned off from on is set by the resistor R2.

  The same applies to the MOSFET Q2. The dV / dt when the Q2 is turned from OFF to ON is set by the resistor R3, and the dV / dt when the Q2 is turned from ON to OFF is set by the resistor R4.

  As is apparent from the above description, the resistors R1, R2, R3, and R4 are setting units that set the rate of voltage change between the drain and source of the MOSFETs Q1 and Q2.

  The setting of the voltage change rate dV / dt has been described above. Next, the current change rate dI / dt will be described.

  The current change rate dI / dt of the drain current when the MOSFET Q1 shifts from OFF to ON is generated while the drive coil terminal voltage VU is changing in FIG. While VU is changing, the signal HO hardly changes in the vicinity of the threshold voltage Vth of the MOSFET Q1 due to the effect of the mirror effect as described above, but actually changes slightly. The current change rate dI / dt of the collector current of MOSFET Q1 is determined by the slight change rate in the vicinity of Vth and the mutual conductance of MOSFERTQ1. Here, the slight change rate of the signal HO near Vth can be set by the resistor R1 or the capacitor C1 between the gate and the source of the MOSFET Q1. Therefore, by setting the mutual conductance of the resistor R1, the capacitor C1, or the MOSFET Q1, the current change rate dI / dt of the collector current of the MOSFET Q1 can be set. However, the resistor R1 is used to set the voltage change rate dV / dt described above. Therefore, the current change rate dI / dt is set by the mutual conductance of the capacitor C1 or the MOSFET Q1.

  In the above description, the MOSFET Q1 is switched from off to on. Similarly, when Q1 is switched from on to off, the current change rate dI / dt of the collector current of the MOSFET Q1 is similarly determined by the mutual conductance of the capacitor C1 or the MOSFET Q1. Can be set.

  The same applies to MOSFET Q2, and the collector current dI / dt of Q2 can be set by the mutual conductance of capacitor C2 or MOSFET Q2.

  As is clear from the above description, the mutual conductance of the capacitors C1 and C2 and the MOSFET Q1 or the mutual conductance of the MOSFET Q2 is a setting unit for setting the current change rate of the drain current of the MOSFETs Q1 and Q2.

  FIG. 9 is an operation diagram when the time t2 when the input signal HIN switches from the high level to the low level and the time t3 when the input signal LIN switches from the low level to the high level are close to each other in the circuit configuration of FIG. This shows a case where the output voltage LO starts to rise at time t = t3 before the output signal HO which has started falling at time t = t2 falls below the threshold voltage Vth. In this case, if MOSFET Q2 is turned on before MOSFET Q1 is turned off, a through current flows from MOSFET Q1 to MOSFET Q2, and these MOSFETs are destroyed.

  In order to prevent such a through current, the relationship between the resistor R1 and the resistor R2 as a setting unit is set to R1 >> R2 so that at least time t = t20 is before time t = t30. It is determined in advance.

  The time from the time t = t2 when the input signal HIN switches from the high level to the low level to the time t = t3 when the input signal LIN switches from the low level to the high level is generally called a dead time. This dead time is set sufficiently large with respect to the delay time usually caused by the gate driver 11 and the MOSFET 8 and its peripheral components. However, on the other hand, if the dead time becomes long, the power supply to the drive coil is cut off during this period, and therefore, in the case of household appliance fans with an axial output of 20 W to 50 W, problems such as noise and vibration often occur. Therefore, it is necessary to make the dead time as small as possible, and it is necessary to thoroughly examine the resistance R1, the resistance R2, and the gate capacitor capacitance value in advance.

  FIG. 10 is an operation explanatory diagram when the threshold voltage Vth of the MOSFET itself is increased from Vth1 to Vth2. In this case, the MOSFET Q1 has a short delay time from on to off, and conversely, the MOSFET Q2 has a long delay time from off to on. Accordingly, in the circuit configuration of FIG. 6, when the time t2 when the input signal HIN switches from the high level to the low level and the time t3 when the input signal LIN switches from the low level to the high level are close, that is, when the dead time is extremely small. However, it is possible to provide a brushless DC motor in which the MOSFET Q2 is not turned on before the MOSFET Q1 is turned off.

  As described above, according to the brushless DC motor of the present invention, it is configured as a power module in which at least a MOSFET and a gate driver are integrated with a mold resin, and includes a drive circuit including the power module. By making it possible to set the electrical strength of the MOSFET in the setting part included in the gate driver or in the MOSFET, it is possible to provide a brushless DC motor that is small and lightweight, easy to mount and wire, and highly reliable. .

  Next, the electric device of the present invention provided with the brushless DC motor 1 will be described. FIG. 11 is a configuration diagram of an electric device (air conditioner outdoor unit) according to the second embodiment of the present invention.

  In FIG. 11, the electric apparatus in Example 2 has the following structure. The air conditioner outdoor unit 51 is partitioned into a compressor chamber 56 and a heat exchanger chamber 59 by a partition plate 54 erected on the bottom plate 52. A compressor 55 is disposed in the compressor chamber 56. The heat exchanger chamber 59 is provided with a heat exchanger 57 and a fan motor 58 for blowing air. An electrical component box 60 is disposed on the upper part of the partition plate 54.

  The fan motor 58 is configured by attaching a blower fan to the rotating shaft of the brushless DC motor 1 described in the first embodiment. The fan motor 58 is supplied with a high-voltage DC voltage Vdc and a control voltage Vcc from a power supply device 53 housed in the electrical component box 60. The blower fan rotates as the fan motor 58 rotates, and the heat exchanger chamber 59 is cooled by the wind. As described in the first embodiment, this brushless DC motor 1 has a built-in drive circuit, and thus is compactly configured, easily mounted and wired, and has high functionality and low electrical equipment such as an air conditioner. It can contribute to price.

  FIG. 12 is a schematic circuit diagram of an electric device (air conditioner outdoor unit) according to the second embodiment of the present invention. In FIG. 12, a commercial power supply 62 is input to the power supply device 53. The power supply device 53 includes a rectifier, a smoothing capacitor, a switching power supply device, and the like, outputs a high-voltage DC voltage Vdc and a control voltage Vcc, and supplies it to the fan motor 58. In addition, the high-voltage DC voltage Vdc is input to the inverter device 61 and drives the compressor 55.

  As the inverter device 61 is turned on / off, a surge voltage (not shown) is superimposed on the high-voltage DC voltage Vdc, and sometimes the breakdown voltage of the MOSFET built in the fan motor 58 may be exceeded. However, the MOSFET itself has an avalanche resistance, and it is possible to provide a highly reliable fan motor that can sufficiently withstand short-time overvoltage and does not break down.

  In addition, although the air conditioner outdoor unit has been described as an example of the electrical apparatus in the second embodiment, by applying the present invention also to the fan motor for blowing installed in the air conditioner indoor unit and the air conditioner indoor unit, The same effect as in the case of an air conditioner outdoor unit can be expected.

  The brushless DC motor of the present invention includes a stator assembly having a plurality of phase drive coils and a rotor assembly having a permanent magnet, and includes a printed wiring board having a drive circuit for driving the drive coil. Includes a MOSFET that supplies power to the drive coil, a gate driver that controls the MOSFET, and a pre-driver that supplies a PWM signal to the gate driver, and the printed wiring board includes at least the MOSFET and the gate driver as a mold resin material. The power module is mounted, and the power module includes a setting unit for setting the electrical strength of the MOSFET inside the gate driver or inside the MOSFET. The present invention further includes an electric device equipped with the brushless DC motor.

  With this configuration, it is possible to provide a brushless DC motor that is small and lightweight, easy to mount and wire, and highly reliable, and an electric device equipped with the brushless DC motor.

DESCRIPTION OF SYMBOLS 1 Brushless DC motor 2 Lead wire assembly 3 Stator assembly 4 Bracket 5 Shaft 6 Drive circuit 7 Printed wiring board assembly 8 MOSFET
9 High Voltage DC Power Supply 10 Power Module 11 Gate Driver 12 Predriver 13 Printed Wiring Board 14 Bearing 15 Insulating Plate 16 High Thermal Conductive Resin Material 17 Permanent Magnet 18 Rotor Yoke 19 Rotor Assembly 20 Stator Core 21 Drive Coil 22 Terminal Pin
23 Control power supply 25 Magnetic sensor 27 Lead electrode 28 Frame 29 Mold resin material 30 Bonding wire 31 Individual parts 51 Electric equipment (air conditioner outdoor unit)
53 Power supply Q1, Q2 MOSFET
R1, R2, R3, R4 Resistor C1, C2, C3, C4 Capacitor SW1, SW2, SW3, SW4 Electronic switch

Claims (12)

A brushless DC motor including a stator assembly having a plurality of phases of drive coils, a metal bracket covering one end of the stator assembly, and a rotor assembly having a permanent magnet,
The brushless DC motor has a built-in printed wiring board on which a drive circuit for driving the drive coil is mounted,
The printed wiring board is fixed to the stator assembly and built in the brushless DC motor such that an insulating plate is disposed between the bracket and the bracket.
The drive circuit is
(A) a MOSFET for supplying power to the drive coil;
(B) a gate driver for controlling the MOSFET;
(C) a pre-driver for supplying a PWM signal to the gate driver;
And here,
The printed wiring board is mounted with a power module in which the MOSFET and the gate driver are integrated with a mold resin material,
The power module is
The MOSFET, the gate driver, a lead electrode bent in the direction of the printed wiring board, and a frame in which the MOSFET and the gate driver are bonded and fixed to the bending direction side of the lead electrode,
A setting unit for setting the electrical strength of the MOSFET inside the gate driver or inside the MOSFET or both,
The MOSFET and the gate driver are connected by a bonding wire and sealed with an epoxy resin that is the mold resin material;
A brushless DC motor, wherein the power module is mounted on the bracket side of the printed wiring board and configured to radiate heat to the bracket via a silicon resin material having high thermal conductivity and elasticity. The brushless DC motor according to claim 1, wherein
The setting unit includes a resistor that sets a voltage change rate between the drain and source of the MOSFET when the MOSFET is turned on from off, and a drain and source between the MOSFET when the MOSFET is turned on from off A brushless DC motor comprising a resistor for setting the voltage change rate. The brushless DC motor according to claim 2,
The resistor of the setting unit sets the voltage change rate between the drain and the source of the MOSFET when the MOSFET is turned on from off, and the resistor of the MOSFET when the MOSFET is turned off from on A brushless DC motor set to be larger than a resistor that sets the rate of voltage change between the sources; In the brushless DC motor according to any one of claims 2 and 3,
The setting unit is a brushless DC motor configured by a capacitor that is connected between the gate and source of the MOSFET and sets a current change rate of the drain current of the MOSFET. The brushless DC motor according to claim 1, wherein
The drive circuit further includes a magnetic sensor for detecting a magnetic pole position of the permanent magnet, and the magnetic sensor is mounted on the printed wiring board. The brushless DC motor according to claim 1, wherein
The brushless DC motor having a configuration in which the setting unit sets the on / off delay time of the MOSFET to a predetermined value. The brushless DC motor according to claim 6,
The brushless DC motor having a configuration in which the setting unit further includes a threshold voltage of the gate of the MOSFET, and the threshold voltage is set to a predetermined value. The brushless DC motor according to claim 1, wherein
The MOSFET is a brushless DC motor including a MOSFET having a predetermined avalanche resistance. An electric device equipped with the brushless DC motor according to claim 1. The electrical device is an air conditioner;
The electric device according to claim 9, wherein the brushless DC motor is a fan motor. The electrical device further includes a power supply device and a device other than the brushless DC motor,
The electrical apparatus according to claim 10, wherein both the brushless DC motor and a device other than the brushless DC motor are connected to the power supply device. The electric device is an air conditioner outdoor unit;
The brushless DC motor is a fan motor,
The electrical apparatus according to claim 11, wherein the device other than the brushless DC motor is a compressor.