JP2007185013A - Brushless motor with built-in high withstand voltage pre-driver ic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the constitutional simplification and the downsizing of a drive unit for a brushless motor and the downsizing of the brushless motor having the above drive unit within, by reducing the number of parts by a high withstand voltage pre-driver IC with a built-in motor control LOGIC. <P>SOLUTION: The gate driver IC chip and the pre-driver IC chip of the drive unit for the brushless motor are integrated by epoxy mold resin into one high withstand voltage pre-driver IC, whereby it is made into such simple constitution that the main components on a printed wiring board being the embodiment of the drive unit are only the above high withstand voltage pre-driver IC, a MOSFET, and peripheral passive parts. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to miniaturization of a brushless motor and a printed wiring board with a built-in brushless motor.

  A small brushless motor with a shaft output of about 20 to 50 W used for blower fans of various home appliances such as room air conditioners has a built-in drive device that is configured by arranging various electronic components on a printed wiring board. Things are common.

  101 shows an example of the prior art, FIG. 12 is an external view of a conventional three-phase brushless motor 101, FIG. 13 is a cross-sectional view showing the internal structure, FIG. 14 is a circuit configuration diagram of the driving device 106, FIG. 15 shows a printed wiring board assembly 107 that embodies the driving device 106. FIG. 16 is a circuit configuration diagram showing details of the connection between the MOSFET, which is a main component of the driving device 106, and a high voltage gate driver IC (HVIC) for one phase.

  Since the MOSFET used as the switching element has an avalanche resistance, a pulse-like overvoltage exceeding the MOSFET withstand voltage such as a surge is superimposed on the positive output Vdc of the motor power supply DC power supply 109 in FIG. However, if it is within the above, there is a great effect in terms of reliability that the MOSFET will not be destroyed. On the other hand, as shown in FIG. 16, there is a dV / dt, di between the HVIC and the MOSFET gate. / Dt and at least six passive components such as resistors, capacitors, and diodes are required for each gate for the purpose of setting the ON / OFF delay time to a desired value, and 6 × 6 or 36 for driving a three-phase motor. Passive components are required. Therefore, the printed wiring board assembly shown in FIG. 15 has a MOSFET array 110 in which six MOSFET chips are packaged in one package, three HVICs 111, and a number of passive components (not shown) other than the pre-drive IC 112 are soldered and mounted. In one example, the number is about 100, which makes it difficult to further reduce the size of the printed wiring board.

In addition, there are monolithic ICs that drive devices instead of MOSFETs, and power modules that integrate MOSFETs and high-voltage gate driver ICs (HVICs). There is a design problem that the rated wattage of a motor that can be applied is limited due to space constraints, and various characteristics such as delay time of a MOSFET are restricted (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 3-270677

  The problem to be solved is that when a drive device built in a brushless motor is realized using a MOSFET, the number of components is large and the device cannot be miniaturized.

  According to the present invention, a plurality of gate driver ICs and pre-drive ICs of a driving device are integrally molded with an epoxy mold resin to form one high voltage pre-drive IC. It is characterized by a simple configuration comprising only a high voltage pre-drive IC and peripheral passive components.

  A brushless motor with a built-in high-voltage pre-drive IC according to the present invention has the above-described configuration, and uses a MOSFET having an avalanche resistance as a switching element, while reducing the number of electronic components on a printed wiring board that embodies the drive device, There is an advantage that the circuit board can be miniaturized and can contribute to the miniaturization of the brushless motor itself.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 is an external view of a brushless motor of the present invention. A lid-like bracket 4 and a shaft 5 protrude from a stator mold assembly 3, and a lead wire assembly 2 extends from a side surface of the stator mold assembly 3.

  FIG. 2 is a cross-sectional view of the brushless motor of the present invention. A stator mold assembly 3 in which a stator core 20 provided with a drive coil 21 is integrally molded with an unsaturated polyester resin, a shaft 5, a bearing 14, a rotor yoke 18, and a magnet 17 are provided. The arranged rotor assembly 19 is accommodated, and the printed circuit board 13 on which the MOSFET array 10, the high withstand voltage pre-drive IC 51, the rotor magnetic pole position sensor 25 and peripheral parts (not shown) are mounted by soldering is disposed, and the insulating plate 15 is disposed thereon. It has a structure that is placed and covered with a bracket 4. The gap between the power module 10 and the bracket 4 is filled with heat dissipation silicon 16.

  FIG. 3 is a circuit diagram of the brushless motor driving device 6 according to the present invention. The magnetic pole position sensor 25, the pre-drive IC 12 and the three HVICs 11 are integrated, and the high-voltage pre-drive IC 51 and the six MOSFETs 8 are integrated. The output from the high-voltage DC power supply 9, the control power supply 23, and the speed control signal source 24 is connected to each input terminal of the brushless motor driving device 6, and the output terminal has a three-phase output. In this configuration, the connected drive coil 21 is connected.

  FIG. 4 is a cross-sectional view of the high-voltage pre-drive IC 51. The HVIC 11 and the pre-drive IC 12 that are bonded and fixed to the frame 28 are connected to each other or between the lead electrodes 27 with a bonding wire 30 and integrated with an epoxy resin 29. It is a molded configuration.

  FIG. 5 is a plan view of the printed wiring board assembly 7. On the printed wiring board 13, a MOSFET array 10 and a high voltage pre-drive IC 51 are arranged as main components.

  FIG. 6 shows a small printed wiring board assembly 31 with a diameter of 68 ± 5 mm, which embodies the drive device of a small brushless motor with a peripheral diameter of 78 ± 5 mm of the present invention, and the printed wiring of FIG. 5 according to the first embodiment. This is a configuration in which the MOSFET array 10 and the high voltage pre-drive IC 51 are arranged as main components on a small-diameter printed wiring board 13a whose diameter is smaller than that of 81 ± 5 mm.

  FIG. 7 is a cross-sectional view of the small-diameter brushless motor 32 of the present invention, which incorporates the small-diameter printed wiring board assembly 31 of FIG. 6 and has a smaller motor outer diameter than the brushless motor 1 of the first embodiment. This is the configuration.

FIG. 3 is a circuit configuration of the brushless motor driving apparatus of the present invention. FIG. 3 is a detailed configuration diagram of one phase of the high-voltage pre-drive IC 51 including the pre-drive IC 12 and the HVIC 11 of FIG. 3 and the MOSFET 8. In addition, the output terminal of the HVIC 11 has two outputs, HOso and HOsi on the high side and LOso and LOsi on the low side, and a first gate resistor 38 and a second gate are provided between each output terminal and the gate of the MOSFET. Connection is made through a gate resistor 39.

  3 is a detailed configuration diagram of the brushless motor driving apparatus of the present invention shown in FIG. 3, in which the capacitance value of the gate capacitor 37 of the MOSFET 8 and the first gate resistor 38 and the second gate resistor 39 connected to the output terminal of the HVIC 11 are shown. The ON / OFF delay time of the MOSFET 8 can be set to a desired value by arbitrarily setting the resistance value.

    Next, specific examples of the present invention will be described.

  In the circuit configuration diagram of the brushless motor driving apparatus 6 of the present invention shown in FIG. 3, the rotor magnetic pole position sensor 25 inputs the magnetic pole position information of the magnet 17 of the rotor assembly 29 to the pre-drive IC 12. The pre-drive IC 12 inputs a PWM signal to the HVIC 11, and the HVIC 12 amplifies and outputs the input signal and acts on each gate of the MOSFET 8, thereby controlling the MOSFET 8 on / off to the drive coil, Power is supplied from the high-voltage DC power supply 9.

  As shown in FIG. 4, the pre-drive IC 12 and the HVIC 11 which are the constituent elements of the brushless motor driving device 6 performing the above-described operation are integrally molded with an epoxy resin 29 to form a high-voltage pre-drive IC 51. The two main components of the MOSFET array 10 and the high withstand voltage pre-drive IC 51, peripheral parts (not shown) and the lead wire assembly 2 are provided on the printed wiring board 13 to form the printed wiring board assembly 7, thereby driving the brushless motor. The device 6 is embodied with a simple configuration. The printed wiring board assembly 7 is incorporated in the brushless motor 1 as shown in the cross-sectional view of FIG. 2 to constitute the brushless motor with a built-in high voltage pre-drive IC of the present invention shown in FIG.

  In FIG. 6, the small-diameter printed wiring board assembly 31 is obtained by reducing the outer shape of the printed wiring board 13 of the printed wiring board assembly 7 in FIG. 5 without changing the main component MOSFET array 10 and the high breakdown voltage predrive IC 51. Thus, by providing the small-diameter printed wiring board assembly 31 as a brushless motor driving device as shown in the sectional view of FIG. 7, the outer diameter of the brushless motor itself is compared with that of the brushless motor 1 shown in FIG. This makes it possible to realize a brushless motor 32 having a reduced diameter. Although only the motor outer diameter is reduced in FIG. 7, the magnet 17 and the rotor yoke 18 of the rotor assembly 19 may be reduced in size.

FIG. 9 shows the ON / OFF operation of the HVIC 11 and the MOSFET 8 shown in FIG. 8, and at time t <t1, the first and third switches 40, 42 are OPEN, and the second and fourth switches 41, 43. Is CLOSE, the gate voltages VGa and VGb of QA and QB maintain L, and the MOSFETs Q _A and Q _B are in the OFF state. When the PWM signal input to HIN is switched from L to H at time t = t1, the second switch element 41 becomes OPEN, the first switch element 40 becomes CLOSE, and the accumulated charge of the boot capacitor 36 becomes Although supplied to the gate of the MOSFET Q _A , VGa rises with a certain time constant by the first gate resistor 38 and the gate capacitor 37. When VGa reaches the threshold voltage Vth of the MOSFET Q _A and t = t1 ′, the MOSFET Q _A is turned ON. When the MOSFET Q _A is turned on, power is supplied to the drive coil 21 from a high-voltage DC power supply (Vdc). Next, at time t = t2, when the PWM signal input to HIN switches from H to L, the first switch element 40 is OPEN, the second switch element 41 is CLOSEd, and the gate capacitor 37 and the second gate are switched. VGa falls with a time constant with the resistor 39, the MOSFET Q _a when VGa is MOSFET Q t = t2 falls below the threshold voltage Vth of _a 'is O
FF. Are the same ON / OFF operation of the subsequent time t3 after MOSFET Q _B explanation is omitted.

FIG. 10 is a diagram in which the time t1 in FIG. 9 is enlarged and a change in the drive coil terminal voltage VU is added. When HIN switches from L to H at time t1, VGa starts to rise at t11 after the transmission time of the hysteresis comparator 45, the level shift means 44, and the first switch element 40 has elapsed. (In FIG. 9, the transmission time is omitted.)
Then the VGa at time t1 'reaches Vth, MOSFET Q _A is ON Suruga, in fact Vth, MOSFET Q _A itself time or drive coil terminal voltage VU ranging from OFF to ON to Vdc from 0V in the figure There is a certain width ΔVth that changes. The voltage change rate dV / dt at which the drive coil terminal voltage VU changes from 0 V to Vdc is such that the dV / dt increases as the time t12 to t13 required for VGa to pass through ΔVth is shorter, and conversely as the voltage tV from t12 to t13 increases. dt becomes large. Needless to say, the time from V12 to t13 depends on the time constant determined by the resistance value of the first gate resistor 38 and the capacitance value of the gate capacitor 37. For example, when a motor is used for home appliances, the resistance value of the first gate resistor 38 and the capacitance value of the gate capacitor 37 are determined in advance so that dV / dt is about 2 kV / μsec. Since the operation from ON to OFF at time t2 in FIG. 9 only shows the reverse operation of the above description, the description is omitted. In FIG. 8, a gate capacitor is built in the MOSFET, but a MOSFET without a gate capacitor may be used by externally attaching a capacitor between the gate and the source.

FIG. 11 is an operation diagram when time t2 at which HIN switches from H to L and time t3 at which LIN switches from L to H are close to each other in the circuit configuration of FIG. VGa that at time t2 began falling becomes the time t3 before the below Vth when VGb will begun rising, so as not to MOSFETQB will be ON before the MOSFET Q _A is OFF, at least t2 The resistance value R2 of the 39 second gate resistance and the resistance value R1 of the first gate resistance of 38 are determined in advance so that R1 >> R2 so that “is before t3”.
The time from the time t2 at which HIN switches from H to L to the time t3 at which LIN switches from L to H is generally called a dead time, and is usually sufficiently larger than the delay time that occurs in the HVIC 11 and MOSFET 8 and its peripheral components. However, if the dead time becomes longer, the power supply from the high-voltage DC power supply to the drive coil is cut off due to the dead time, so in the case of a fan for household appliances with an axial output of 20 W to 50 W, sound and vibration are generated. Therefore, it is necessary to intentionally reduce the dead time as much as possible, and it is necessary to sufficiently examine R1, R2 and the gate capacitor capacitance value in advance.

  It can be used not only for blower fans for home appliances, but also for various devices that are high voltage and have a load of about 20 W to 50 W.

External view of the brushless motor of the present invention Sectional view of the brushless motor of the present invention Circuit configuration diagram of brushless motor drive device of the present invention Sectional drawing of the high voltage | pressure-resistant predrive IC used for the drive apparatus of the brushless motor of this invention Printed wiring board assembly diagram embodying the brushless motor drive device of the present invention Printed wiring board assembly diagram embodying the small diameter brushless motor drive device of the present invention Cross-sectional view of small diameter brushless motor of the present invention Internal circuit diagram of a high withstand voltage pre-drive IC used in the brushless motor driving apparatus of the present invention Diagram showing ON / OFF operation of HVIC and MOSFET The figure which expanded time t1 and added the change of drive coil terminal voltage VU In the circuit configuration of FIG. 8, an operation diagram when time t2 at which HIN switches from H to L and time t3 at which LIN switches from L to H are close to each other. External view of conventional three-phase brushless motor Sectional view of a conventional three-phase brushless motor Circuit diagram of conventional three-phase brushless motor drive device Printed circuit board assembly diagram of conventional 3-phase brushless motor drive Detailed circuit diagram of MOSFET and HVIC of conventional three-phase brushless motor driver

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brushless motor of this invention 2 Lead wire assembly 3 Stator mold assembly 4 Bracket 5 Shaft 6 Brushless motor drive device 7 Printed wiring board assembly 8 MOSFET
9 High Voltage DC Power Supply 10 MOSFET Array 11 High Voltage Gate Driver IC (HVIC)
12 Pre-drive IC
13 Printed Wiring Board 14 Bearing 15 Insulating Plate 16 Heat Dissipating Silicon 17 Magnet 18 Rotor Yoke 19 Rotor Assembly 20 Stator Core 21 Drive Coil 22 Terminal Pin
23 Control power source 24 Speed control signal source 25 Rotor magnetic pole position sensor 26 Current detection resistor 27 Lead electrode 28 Frame 29 Epoxy resin 30 Bonding wire 31 Small diameter printed wiring board assembly 32 Small diameter brushless motor 33 Small diameter bracket 34 Small diameter stator mold assembly 35 High-speed diode 36 Boot capacitor 37 Gate capacitor 38 First gate resistor 39 Second gate resistor 40 First switch 41 Second switch 42 Third switch 43 Fourth switch 44 Level shift means 45 Hysteresis comparator 51 High Withstand voltage pre-drive IC
13a Small printed wiring board 101 Conventional brushless motor 102 Lead wire assembly 103 Stator mold assembly 104 Bracket 105 Shaft 106 Conventional motor driving device 107 Conventional printed wiring board assembly 108 MOSFET
109 High Voltage DC Power Supply 110 Conventional MOSFET Array 111 High Voltage Gate Driver IC (HVIC)
112 Pre-drive IC
113 Conventional printed wiring board

Claims (5)

A plurality of MOS gate switch elements that supply power to the drive coils of a multi-phase brushless motor, a plurality of gate driver ICs that act on the gates of the switch elements to perform ON / OFF control, and PWM to the gate triber IC A brushless motor incorporating a pre-IC that outputs a signal, a peripheral component such as a resistor, a capacitor, and a printed wiring board provided with a lead wire,
A plurality of gate driver IC chips and pre-drive IC chips of the driving device are integrally molded with an epoxy mold resin to form a single high-voltage pre-drive IC. A brushless motor characterized by a simple configuration comprising only a drive IC and a plurality of switch elements and peripheral passive components. 2. The brushless motor according to claim 1, wherein a plurality of MOS gate switch elements of the driving device are integrated with an epoxy mold resin to form a MOS array. A plurality of gate driver ICs and pre-drive ICs of the driving device are integrally molded with epoxy mold resin to form one high-voltage pre-drive IC, and the diameter of the outer periphery of the brushless motor that is not the high-voltage pre-drive IC is 87 mm or more. 3. The brushless motor according to claim 2, wherein the brushless motor is miniaturized to an outer peripheral diameter of 87 mm or less. 4. The brushless motor according to claim 1, wherein an output terminal of a gate triber IC which is a component of the high withstand voltage pre-drive IC is a two-output terminal of a source output and a sink output. 5. The brushless motor according to claim 1, wherein a capacitor is built in a gate of a MOS gate switch element built in a MOS array which is a component of the driving device.

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