JP2009095212A - Drive unit for blushless dc motor, and ventilating airblower equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ventilating airblower equipped with a blushless DC motor, such as a range hood, which stops without fail in a stable manner even if the motor gets slower in revolution, and achieves a reduction in the thickness of the range hood while preventing an increase in the time required for stopping a large-sized blast fan to enable quick and sure stoppage of the ventilating airblower. <P>SOLUTION: The ventilating airblower includes a reverse torque current-passing means 8 which instructs the blushless DC motor to revolve in the direction reverse to the direction of revolution at startup to stop the blushless DC motor in operation. The ventilating airblower also includes upper arm switching elements Q1, Q2, and Q3 and lower arm switching elements Q4, Q5, and Q6, which are turned on and off to make switchover in current passing to quickly and surely stop the DC motor in a stable manner. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ventilation blower, for example, a drive device when a range hood used in a kitchen is driven by a brushless DC motor. The present invention relates to a driving device to be stopped.

  Conventionally, this type of brushless DC motor and its driving device are efficient (power saving) and have excellent durability, so that a ventilation fan that is driven for a long time, such as a range hood or a ceiling-mounted ventilation fan. It has come to be mounted on. Moreover, from the request | requirement of the thinness by the air volume improvement and design property of a ventilation air blower, for example, the turbofan mounted in the range hood is calculated | required by the enlargement and thickness reduction. In particular, in the case of a range hood, it is required that the rotating blades can be quickly stopped to work safely in order to clean the filter and blades from oil stains.

  FIG. 10 shows an example in which a DC motor is mounted on a conventional range hood and is actually installed in a kitchen. FIG. 10A is an explanatory diagram of a range hood. The range hood 119 has a structure in which a brushless DC motor 102 and a brushless DC motor driving device 112 are mounted inside a cabinet 115. The brushless DC motor 102 is a brushless DC motor. It is driven by the driving device 112. The brushless DC motor 102 has a structure in which a blower fan 116 is attached and a hood 118 and a filter 117 are attached to the lower part of the range hood 119.

  Hot air, smoke and steam generated when cooking in the kitchen are blown through the filter 117 from the central portion of the hood 118 as the blower fan 116 attached to the brushless DC motor 102 rotates. FIG. 10B shows an installation state of the range hood. The range hood 119 blows air by rotating a blower fan 116 attached to the brushless DC motor 102, and an exhaust port provided on the outer wall 120 from the room where the kitchen is located. Through 121, hot air, smoke and steam are exhausted to the outside.

  11 and 12, the position of the conventional rotor is detected by three magnetic sensors of the rotor magnet, and the motor voltage applied to the three-phase stator winding of the brushless DC motor is determined by the combination of the signals. There is known a brushless DC motor driving device that is determined and rotated by energizing a rectangular wave. Also, as a method of stopping the rotation of the brushless DC motor, the stator winding is short-circuited, a motor current is caused to flow from the induced voltage generated by the rotor magnet, and the brake is applied by the reverse torque acting on the rotor magnet and stopped. The method is known. The operation of the brushless DC motor drive device will be described below.

  As shown in FIG. 11, the DC power source 105 supplies a DC voltage to the inverter circuit 101. The inverter circuit 101 has a configuration of a three-phase inverter bridge, Q1, Q2, and Q3 are U, V, and W phase upper arm switching elements. Similarly, Q4, Q5, and Q6 are U, V, and W phases, respectively. Lower arm switching element. Each switching element is connected in parallel with free-wheeling diodes D1, D2, D3, D4, D5, and D6. The brushless DC motor 102 includes a stator 103 and a rotor 104, and three-phase stator windings LU, LV, and LW are arranged on the stator 103 so as to have a phase difference of 120 degrees in electrical angle.

  A current detection resistor 106 for detecting the motor current is connected between the DC power supply 105 and the switching element of the inverter circuit 101.

  In the rotor 104, magnets are alternately arranged with N poles and S poles, and three magnetic sensors HU, HV, HW are arranged in the vicinity thereof so as to have a phase difference of 120 degrees as the position detection means 109, and rotate. A position detection signal for detecting the position of the magnetic pole of the child 104 is output and output to the energizing means 108 incorporated in the microcomputer 110 of the brushless DC motor driving device 112.

  The energizing means 108 switches which of the upper arm switching elements Q1, Q2, Q3 and the lower arm switching elements Q4, Q5, Q6 of the inverter circuit 101 based on the combination of the three position detection signals output from the position detection means 109. An energization signal is output to the drive unit 111.

  The drive circuit 111 applies the motor voltages U +, U−, V +, V−, W +, W− based on the energization signal output from the energization means 108 to the switching elements Q1, Q2, Q3, Q4, Q5, Q6 of the inverter circuit 101. Are output as specific operation signals. The inverter circuit 101 drives the brushless DC motor 102 by actually turning on and off the switching element based on the operation signal of the drive circuit 111.

  On the other hand, the power generation brake means 107 outputs a stop signal to the energization means 108 when trying to stop the brushless DC motor 102. The energization means 108 receives the stop signal and outputs an energization signal for turning on the lower arm switching elements Q4, Q5, Q6 of the inverter circuit 101 to the drive circuit 111.

  The drive circuit 111 outputs an operation signal for turning on the lower arm switching elements Q4, Q5, Q6 of the inverter circuit 101 based on the energization signal output from the energization means 108. The inverter circuit 101 actually turns on the lower arm switching elements Q4, Q5, and Q6 based on the operation signal of the drive circuit 111 to brake the brushless DC motor 102 and stop it.

  FIG. 12 shows the waveforms of the respective parts, FIG. 12A shows waveforms during driving, and HU, HV, and HW are combinations of position detection signals output from the position detection means 9. U +, U−, V +, V−, W +, and W− are combinations with respect to the position detection signal of the energizing means 108. For example, for the combination of (HU, HV, HW) = (H, H, L), U +, U−, V +, V−, W +, W −) = (L, H, PWM, L, L, H) energization signals are output. Here, PWM is a signal that alternately outputs H and L signals, changes the width ratio of the H and L signals, and adjusts the motor voltage. An energization signal as shown in the figure is output corresponding to a combination of position detection signals that sequentially change in accordance with the rotation of the rotor 104.

FIG. 12B shows a waveform when the brake is applied and stopped, and (U +, U−, V +, V−, W +, W −) = (L, H, L, H) in relation to the position detection signal. , L, H). If the motor current increases and the rotor magnet may be demagnetized, (U +, U−, V +, V−, W +, W −) = (L, PWM, L) to reduce the motor voltage. , PWM, L, PWM). Thus, when the brake is applied, the motor becomes a generator and the motor current is generated by the induced voltage generated in the three-phase stator windings LU, LV, and LW of the stator 103 from the magnet of the rotor 104. Then, a torque opposite to the rotation direction is generated between the motor current and the magnet, and the rotation stops earlier than usual.
Japanese Patent Laid-Open No. 4-129594

  However, in such a conventional configuration, when the brake is applied, the induced voltage generated in the three-phase stator windings LU, LV, LW of the stator 103 is smaller than the magnet of the rotor 104 when the rotational speed is slow. Therefore, there is a problem that the motor current is reduced, the reverse rotation torque generated between the motor current and the magnet is reduced, and the time until stopping is increased. It is required to stop quickly.

  In addition, in such a conventional configuration, when the brake is applied, a phenomenon may occur in which the motor current increases rapidly and abnormal noise is generated or the magnet of the rotor 4 is demagnetized. It is required to prevent such a phenomenon and to stop it reliably and stably.

  In the case of a range hood, it is necessary to increase the size of the blower fan 116 in response to a request to increase the air volume, and the time until the blower fan 116 is stopped is further increased, and a mechanical brake (not shown) is used as a countermeasure. When installed in the cabinet 115, there is a problem that the thickness of the range hood increases, and it is required not to lengthen the waiting time until the large blower fan stops while realizing a thin shape for design. .

  Further, when cleaning the oil stains on the filter 117 of the range hood and the blower fan 116, it is necessary to work after the blower fan 116 is stopped reliably, so the waiting time until the blower fan stops must be reduced. Therefore, it is required that the rotating fan can be stopped quickly and reliably and can be operated safely.

  The present invention solves such a conventional problem, and even if the rotational speed of the brushless DC motor becomes slow, it can stop quickly, reliably and stably, and for the design of the range hood A brushless DC motor that can reduce the waiting time before stopping the blower fan that has become thin and large, and can be stopped quickly and reliably and stably. An object is to provide a driving device and a ventilation blower such as a range hood.

  In order to achieve the above object, a brushless DC motor driving apparatus according to the present invention includes an inverter circuit in which a plurality of switching elements are bridge-connected to a DC power supply, and a three-phase stator connected via the inverter circuit. A brushless DC motor having a winding and a rotor, and a brushless DC motor driving device for turning on and off the switching element of the inverter circuit and switching the energization by energizing the rectangular wave to apply and rotate the motor voltage. In order to stop the motor from the driving state, reverse torque energizing means for instructing to rotate in the rotation direction opposite to the rotation direction at the time of driving is provided, and energization switching is performed by turning on and off the switching element.

  By this means, there is provided a brushless DC motor driving device that can prevent the reverse rotation torque from being reduced because the motor current does not become small even when the rotational speed is slow, and can stop quickly even if the rotational speed becomes slow. can get.

  The other means includes a current detection means for detecting the motor current of the brushless DC motor and a motor voltage correction means for changing the motor applied voltage in accordance with the magnitude of the motor current.

  By this means, the motor-applied voltage can be changed according to the magnitude of the motor current, and a lacyless DC motor driving device that can be stopped quickly, reliably and stably is obtained.

  The other means is provided with motor voltage correction means for initially reducing the motor applied voltage, gradually increasing the voltage thereafter, and then changing the motor applied voltage in accordance with the magnitude of the motor current.

  By this means, it is possible to gradually increase the voltage applied to the motor at first, and to obtain a laciless DC motor driving device that can be stopped quickly and reliably and stably.

  Rotation speed detection means for detecting the rotation speed of the brushless DC motor and motor voltage correction means for changing the motor applied voltage in accordance with the rotation speed.

  By this means, it is possible to change the motor applied voltage according to the number of rotations, and to obtain a laceless DC motor driving device that can be stopped quickly, reliably and stably.

  The other means includes motor voltage correction means for initially reducing the motor applied voltage, gradually increasing the voltage thereafter, and then changing the motor applied voltage in accordance with the rotational speed.

  By this means, the motor-applied electric power is first reduced, then gradually increased, and thereafter the motor-applied voltage can be changed according to the rotational speed, and the laciless DC can be stopped quickly and reliably and stably. A motor drive device is obtained.

  Further, the other means includes a rotation speed detection means for detecting the rotation speed of the brushless DC motor, and stops the motor voltage output from the motor voltage correction means when the rotation speed decreases and immediately before stopping. It is a thing.

  By this means, the motor voltage can be stopped immediately before the stop, and a laciless DC motor drive device can be obtained which can stop quickly, reliably and stably.

  Moreover, another means is a ventilation air blower which mounts the brushless DC motor drive device in any one of Claims 1 thru | or 7.

  This measure eliminates the need for mechanical brakes, and enables a longer waiting time until the large blower fan stops while achieving a low profile for design. A ventilation fan, for example, a range hood, which can be stably stopped and the waiting time can be shortened can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, even if the rotation speed of a brushless DC motor becomes late, the drive device of a brushless DC motor which has the effect of being able to stop stably quickly and reliably can be provided.

  In addition, for example, a ventilation fan such as a range hood can be provided that has the effect of reducing the waiting time until the large blower fan is stopped while realizing a thin shape due to the design of the range hood.

  In addition, for example, a ventilating blower such as a range hood can be provided which has an effect that the rotating blower fan can be stopped quickly and reliably and stably.

  The invention according to claim 1 of the present invention is a brushless having an inverter circuit formed by bridge-connecting a plurality of switching elements to a DC power source, and a three-phase stator winding and a rotor connected via the inverter circuit. In a brushless DC motor driving apparatus that turns on and off a DC motor and a switching element of the inverter circuit and switches energization by applying a rectangular wave and applies a motor voltage to rotate the brushless DC motor from a driving state. A brushless DC motor driving device comprising reverse torque energizing means for instructing to rotate in a rotation direction opposite to the rotation direction during driving, and switching the energization by turning on and off the switching element. It is.

  As a result, the motor voltage is not applied and the motor current is not reduced even when the rotational speed is slow, so that the reverse rotation torque can be prevented from being small, and can be quickly stopped even when the rotational speed is slow.

  According to a second aspect of the present invention, in the brushless DC motor driving apparatus according to the first aspect, a current detection means for detecting a motor current of the brushless DC motor and a motor applied voltage according to the magnitude of the motor current. A brushless DC motor driving device comprising a motor voltage correcting means for changing and changing a motor applied voltage in accordance with the magnitude of the motor current.

  As a result, the voltage applied to the motor can be changed in accordance with the magnitude of the motor current, and the phenomenon that the motor current suddenly increases and abnormal noise is generated or the magnet of the rotor 4 is demagnetized. In addition, since the motor current does not decrease even when the rotation speed is slow, the motor can be stopped quickly and reliably and stably.

  According to a third aspect of the present invention, in the brushless DC motor driving device according to the first or second aspect, the motor applied power is initially reduced, then gradually increased, and thereafter the motor is further increased. The brushless DC motor driving device is characterized in that the motor applied voltage is changed in accordance with the magnitude of the current.

  As a result, the voltage applied to the motor can be gradually increased at the beginning, preventing a phenomenon in which the motor current suddenly increases and abnormal noise occurs or the magnet of the rotor 4 is demagnetized, Even if the rotational speed is slow, the motor current does not decrease, so that the motor can be stopped quickly and reliably and stably.

  According to a fourth aspect of the present invention, in the brushless DC motor driving device according to the first aspect, the rotational speed detecting means for detecting the rotational speed of the brushless DC motor and the motor applied voltage are changed according to the rotational speed. The brushless DC motor driving device includes a motor voltage correcting means for changing the motor applied voltage in accordance with the rotational speed.

  As a result, the voltage applied to the motor can be changed according to the number of revolutions to prevent a phenomenon in which abnormal noise is generated due to a sudden increase in motor current or the magnet of the rotor 4 is demagnetized. Since the motor current does not decrease even when the time is slow, the motor can be stopped quickly and reliably and stably.

  According to a fifth aspect of the present invention, in the brushless DC motor driving device according to the first or fourth aspect, the motor voltage correction means initially reduces the motor applied power and then gradually increases. The brushless DC motor driving device is characterized in that the voltage applied to the motor is changed according to the number of rotations.

  As a result, the power applied to the motor is initially reduced and then gradually increased, and then the motor applied voltage can be changed according to the rotational speed, and the motor current increases rapidly and noise is generated. In addition, the phenomenon that the magnet of the rotor 4 is demagnetized is prevented, and even if the rotational speed is slow, the motor current does not become small, so that it can be stopped quickly and reliably.

  According to a sixth aspect of the present invention, the brushless DC motor driving device according to any one of the first to fifth aspects further comprises a rotational speed detecting means for detecting the rotational speed, and when the rotational speed decreases and immediately before stopping. The brushless DC motor driving apparatus is characterized in that the motor voltage output from the motor voltage correcting means is stopped.

  As a result, the motor voltage can be stopped immediately before stopping, and can be stopped quickly and reliably.

  A seventh aspect of the present invention is a ventilating air blower equipped with the brushless DC motor driving device according to any one of the first to sixth aspects.

  This eliminates the need for a mechanical brake, reduces the waiting time until the large blower fan stops while achieving a low profile for design, and quickly and reliably. A ventilation fan, for example, a range hood that can be stably stopped and shortened the waiting time can be obtained.

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

(Embodiment 1)
FIG. 1 shows a brushless DC motor driving apparatus according to the present invention. In FIG. 1, a DC power supply 5 supplies a DC voltage to the inverter circuit 1. The inverter circuit 1 has a configuration of a three-phase inverter bridge, Q1, Q2, and Q3 are U, V, and W phase upper arm switching elements. Similarly, Q4, Q5, and Q6 are U, V, and W phases, respectively. Lower arm switching element. Each switching element is connected in parallel with free-wheeling diodes D1, D2, D3, D4, D5, and D6. The brushless DC motor 2 includes a stator 3 and a rotor 4, and three-phase stator windings LU, LV, and LW are arranged on the stator 3 so as to have a phase difference of 120 degrees in electrical angle.

  A current detection resistor 6 for detecting a motor current is connected between the DC power supply 5 and the switching element of the inverter circuit 1.

  In the rotor 4, magnets are alternately arranged with N poles and S poles, and three magnetic sensors HU, HV, HW are arranged in the vicinity thereof so as to have a phase difference of 120 degrees as the position detecting means 9, and rotate. A position detection signal for detecting the position of the magnetic pole of the child 4 is output and output to the energizing means 8 incorporated in the microcomputer 10 of the brushless DC motor driving device 12.

  The energizing means 8 switches which of the upper arm switching elements Q1, Q2, Q3 and the lower arm switching elements Q4, Q5, Q6 of the inverter circuit 1 from the combination of the three position detection signals output from the position detecting means 9. An energization signal is output to the drive means 11.

  The drive means 11 converts the motor voltages U +, U−, V +, V−, W +, W− based on the energization signal output from the energization means 8 into the upper arm switching elements Q1, Q2, Q3, and the lower arm switching of the inverter circuit 1. Elements Q4, Q5 and Q6 are output as specific operation signals. The inverter circuit 1 drives the brushless DC motor 2 by actually turning on and off the switching element based on the operation signal of the drive means 11.

  On the other hand, when the reverse torque energizing means 7 tries to stop the brushless DC motor 2, an inverter circuit is obtained from a combination of three position detection signals output from the position detecting means 9 so as to rotate in the reverse rotation direction. An energization signal indicating which one of the upper arm switching elements Q1, Q2, Q3 and one of the lower arm switching elements Q4, Q5, Q6 is to be switched is output to the drive means 11.

  The drive means 11 outputs an operation signal for switching the upper arm switching elements Q1, Q2, Q3 and the lower arm switching elements Q4, Q5, Q6 of the inverter circuit 1 based on the energization signal output from the reverse torque energizing means 7. The inverter circuit 1 actually switches the upper arm switching elements Q1, Q2, Q3 and the lower arm switching elements Q4, Q5, Q6 based on the operation signal of the drive means 11 to brake the brushless DC motor 2 and stop it.

  FIG. 2 shows waveforms of the respective parts, FIG. 2A shows waveforms during driving, and HU, HV, and HW are combinations of position detection signals output from the position detection means 9. U +, U−, V +, V−, W +, and W− are combinations for rotating in the reverse direction with respect to the position detection signal of the energizing means 8, for example, (HU, HV, HW) = (H, H, L ) For the combination of (U +, U−, V +, V−, W +, W −) = (L, H, PWM, L, L, H). Here, PWM is a signal that alternately outputs H and L signals, changes the width ratio of the H and L signals, and adjusts the motor voltage. An energization signal as shown in the figure is output corresponding to a combination of position detection signals that sequentially change in accordance with the rotation of the rotor 4.

  FIG. 2 (b) shows a waveform when rotating in the reverse direction, and a combination of position detection signals output from the position detection means 9, for example, (HU, HV, HW) = (H, H, L). On the other hand, a combination of energization signals of (U +, U−, V +, V−, W +, W −) = (L, L, L, H, PWM, L) is output. The combination of the next position detection signals does not actually rotate in the reverse direction, and is the combination of the position detection signals in FIG. 2A, so (HU, HV, HW) = (L, H, L). The combination of energization signals at this time is (U +, U−, V +, V−, W +, W −) = (PWM, L, L, H, L, L).

  In the above configuration, when the brake is applied, torque in the reverse direction is always applied by the reverse torque energizing means, so that even if the rotation is slowed, the torque is not reduced but quickly stopped.

  FIG. 3 shows the number of revolutions and the elapsed time when the conventional power generation braking means and the reverse torque energizing means are used for stopping, and when the operation is stopped using the reverse torque energizing means of the present invention. In the conventional method, the rotation is difficult to decrease at a low speed. It can be seen that the method of the present invention stops quickly even at a low speed.

  In the present embodiment, a magnetic sensor is used as the position detection means 9, but another, for example, an encoder or the like may be used, and there is no difference in operational effects.

(Embodiment 2)
In FIG. 1, the current detection means 13 is connected between the DC power supply 5 and the inverter circuit 1, detects the motor current, and outputs it to the motor voltage correction means 14. An example of the current detection means is an A / D converter. When the motor current is larger than a predetermined threshold due to the motor current, the motor voltage correcting means 14 corrects the voltage applied to the motor to be small and outputs it to the reverse torque energizing means.

  FIG. 4 shows the motor current and motor voltage when reverse torque is actually applied. When the same motor voltage as that during driving is applied, the motor current increases rapidly. For example, as an example, when the driving motor current is 0.5 A, it increases to 1 A. This is because the phase of the voltage applied to the stator winding is opposite to the induced voltage induced in the stator winding. When this motor current exceeds a threshold value, the motor voltage is lowered to lower the motor current. For example, if the threshold value is 0.7A as an example, the motor voltage is reduced from 60V to 40V so that the motor current does not exceed 0.7A. Since the motor voltage is actually given by PWM, the PWM ON period is shortened.

  In the above configuration, the motor applied voltage can be changed in accordance with the magnitude of the motor current, and the operation can be stopped quickly and reliably and stably.

(Embodiment 3)
In FIG. 1, the motor voltage correction means 14 initially decreases the motor applied voltage, then gradually increases, and then changes the motor applied voltage in accordance with the magnitude of the motor current.

  FIG. 5 shows an example in which the application of the motor voltage is specifically reduced initially, then gradually increased, and thereafter the motor voltage is changed so as to keep the motor current constant. For example, as an example, the 60V motor voltage is lowered to 30V and then gradually increased. Accordingly, the motor current increases smoothly without increasing rapidly, and thereafter, by keeping it constant, the reverse torque can be applied smoothly and to the maximum.

  In the above configuration, the motor applied voltage is first reduced, then gradually increased, and then the motor applied voltage can be changed according to the magnitude of the motor current, so that the motor can be stopped quickly and reliably and stably. .

  In the present embodiment, a specific method for applying the motor voltage has been described. However, the method may be determined according to the characteristics of the motor, and there is no difference in the function and effect.

(Embodiment 4)
In FIG. 1, a rotation speed detection means 15 for detecting the rotation speed of the brushless DC motor from a position detection signal of the position detection means and a motor voltage correction means 14 for changing the motor applied voltage according to the rotation speed are provided. The motor applied voltage is changed according to the above.

  FIG. 6 specifically shows an example of the motor applied voltage when the rotational speed is high and when the rotational speed is low. For example, when rotating at 1000 rpm as an example, the motor voltage of 60V is changed to 30V.

  In the above configuration, the voltage applied to the motor can be changed according to the number of rotations, and the operation can be stopped quickly and reliably and stably.

  In the present embodiment, the method of applying the motor voltage according to the specific number of revolutions is shown. However, the method may be determined in accordance with the characteristics of the motor, and there is no difference in the operational effect.

(Embodiment 5)
In FIG. 1, the motor voltage correction means 14 initially reduces the motor applied voltage, then gradually increases, and then changes the motor applied voltage according to the rotational speed.

  FIG. 7 shows an example of a specific motor applied voltage. For example, when the motor voltage is 60 V, for example, the voltage applied to the motor is changed so as to decrease to 40 V, increase gradually thereafter, and then rotate at 1000 rpm.

  In the above-described configuration, the motor applied power is first reduced, then gradually increased, and thereafter, the motor applied voltage can be changed according to the number of revolutions, and the motor is stopped quickly and reliably.

  In this embodiment, a specific example of the motor voltage is shown. However, the method may be determined according to the characteristics of the motor, and there is no difference in the operation effect.

(Embodiment 6)
In FIG. 1, the rotation speed detection means 15 for detecting the rotation speed is configured to stop the motor voltage output from the motor voltage correction means when the rotation speed decreases and immediately before stopping.

  FIG. 8 shows an example of a specific motor applied voltage.

  In the above configuration, the motor voltage can be stopped immediately before stopping, and the motor voltage can be stopped quickly and reliably.

  In this embodiment, a specific example of the motor voltage is shown. However, the method may be determined according to the characteristics of the motor, and there is no difference in the operation effect.

(Embodiment 7)
FIG. 9 shows a conventional range hood equipped with the brushless DC motor driving apparatus of the present invention.

  In the above configuration, a mechanical brake is not required, and it is possible to prevent a long waiting time until the large blower fan stops while realizing a thin shape for design, and quickly and reliably A ventilation blower capable of stably stopping and shortening the waiting time, for example, a range hood is obtained.

The figure which shows the drive device of the brushless DC motor of Example 1 of this invention. The figure which shows the waveform of each part of a drive device ((a) The figure which shows the waveform of each part at the time of the drive, (b) The figure which shows the waveform of each part at the time of rotating in the reverse direction) The figure which shows the rotation speed and elapsed time of the conventional drive device and the present invention The figure showing motor current and motor voltage when reverse torque is applied The figure which shows the specific example of the voltage applied to a motor similarly The figure which shows the specific example of the voltage applied to a motor similarly The figure which shows the specific example of the voltage applied to a motor similarly The figure which shows the specific example of the voltage applied to a motor similarly The figure which shows the range hood carrying the same drive unit The figure which shows the range hood carrying the drive device of the brushless DC motor of a prior art The figure which shows the drive device of the brushless DC motor of a prior art The figure which shows the waveform of each part of the drive device of a prior art ((a) The figure which shows the waveform of each part at the time of the drive, (b) The figure which shows the waveform of each part at the time of applying the brake and stopping)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inverter circuit 2 Brushless DC motor 3 Stator 4 Rotor 5 DC power supply 6 Current detection resistance 7 Reverse torque energization means 8 Energization means 9 Position detection means 10 Microcomputer 11 Drive means 12 Drive apparatus 13 Current detection means 14 Motor voltage correction means 15 Rotational speed detection means Q1 Upper arm switching element Q2 Upper arm switching element Q3 Upper arm switching element Q4 Lower arm switching element Q5 Lower arm switching element Q6 Lower arm switching element

Claims (7)

An inverter circuit formed by bridge-connecting a plurality of switching elements to a DC power source, a brushless DC motor having a three-phase stator winding and a rotor connected via the inverter circuit, and a switching element of the inverter circuit In a brushless DC motor driving device that turns on and off and switches energization by energizing a rectangular wave to apply and rotate a motor voltage, in order to stop the brushless DC motor from the driving state, the rotation direction is opposite to the rotation direction during driving. A brushless DC motor driving apparatus comprising reverse torque energizing means for instructing to rotate, and switching the energization by turning on and off the switching element. It comprises a current detection means for detecting the motor current of the brushless DC motor and a motor voltage correction means for changing the motor applied voltage according to the magnitude of the motor current, and the motor applied voltage is changed according to the magnitude of the motor current. 2. The brushless DC motor driving device according to claim 1, wherein 3. The motor voltage correcting means reduces the motor applied voltage initially, gradually increases thereafter, and thereafter changes the motor applied voltage according to the magnitude of the motor current. Brushless DC motor drive device. The motor voltage correction means for changing the motor application voltage according to the rotation speed detecting means and the rotation speed detection means for detecting the rotation speed of the brushless DC motor, wherein the motor application voltage is changed according to the rotation speed. The brushless DC motor driving device according to claim 1. 5. The brushless DC module according to claim 1, wherein the motor voltage correction means initially reduces the motor applied power, then gradually increases, and then changes the motor applied voltage according to the number of revolutions. -Data drive device. 6. A rotation speed detection means for detecting the rotation speed of a brushless DC motor is provided, and the motor voltage output from the motor voltage correction means is stopped when the rotation speed decreases and immediately before stopping. The brushless DC motor driving device described. A ventilation blower equipped with the brushless DC motor driving device according to any one of claims 1 to 6.

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