JP2015047000A - Ventilation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ventilation blowing device that can perform an air-flow constant operation with little air-flow dispersion in air-flow control for a ventilation device and does not stop the operation of a motor when instantaneous power failure occurs, so that a user does not feel discomfort.SOLUTION: A ventilation device has a shunt resistor 18 provided every phase of an inverter circuit 15, a current detector 20 for detecting current of each phase flowing in a sensorless brushless DC motor 8 on the basis of an output obtained by amplifying the potential difference between both the ends of the shunt resistor 18 with an amplifying unit 19, and a rotation detector 25 for calculating the rotation number and position of the sensorless brushless DC motor 8 on the basis of the current detected by the current detector 20, thereby performing air-flow constant control. The ventilation device is further provided with a voltage detector 26 for detecting a motor driving voltage. When the motor driving voltage is reduced by a predetermined deviation or more due to instantaneous power failure, a target air flow is reduced. Therefore, the motor is not stopped, and a user does not feel discomfort.

Description

  The present invention relates to an air volume control method for a ventilator such as a fan motor or a ventilator that performs inverter control of an air conditioner or the like.

  A conventional control circuit of this type of blower has the following configuration. First, AC power from an AC power source is converted from AC to DC by an AC / DC converter circuit and smoothed by a capacitor. A DC voltage is generated at both ends of the capacitor and is input to the inverter via the current detector. The six semiconductors constituting the inverter are operated (switched) with each other to drive the motor. Since the current flowing through the motor flows through the inverter and the current detector, the current is detected by the voltage induced at both ends of the current detector.

  The position sensor is mounted so as to generate a signal corresponding to the position of the rotor due to the rotation of the motor. The rotational speed detection unit detects the rotational speed of the motor based on a signal from the position sensor. The rotation speed detected here is output to the air volume calculation unit and the speed control unit. The air volume calculation unit calculates the air volume generated by the fan connected to the motor from the motor current value detected by the current detection unit and the motor rotation speed detected by the rotation speed detection unit. To do.

  In the air volume calculation unit, the air volume calculation unit calculates the air volume from the rotation speed detected by the rotation speed detection unit and the current detected by the current detection unit, and the calculated air volume and target air volume calculated by the target rotation speed calculation unit. And a target rotational speed that is a target of motor operation is calculated so that the deviation becomes zero. The speed controller controls the speed of the motor so as to achieve the target rotational speed calculated by the air volume calculator. Therefore, since the air volume generated by the fan connected to the motor matches the target air volume, the air volume is controlled to be constant (for example, Patent Document 1 below).

  Also, if an instantaneous power failure occurs, the DC voltage smoothed by the capacitor, that is, the voltage that drives the motor will fluctuate greatly, and constant air volume control will not be possible. The configuration is such that the motor is stopped by immediately stopping the voltage application, the discharge of the capacitor is slowed, and the instantaneous power failure guarantee time is extended (for example, Patent Document 2 below).

JP 2002-165477 A Japanese Utility Model Publication No. 61-107003

  In such a conventional blower, the air volume is calculated using the current and the rotational speed, but the current detection unit combines the negative potential side terminals of the switching elements constituting the lower stage of the inverter circuit into one. It was configured to be connected between the location and the circuit ground.

  As a problem in such a blower, the current of the motor is measured by the current detection unit, but since it is connected to the circuit ground, the motor current can be detected only by the three-phase combined current, and the switching element is In the case of a driver assembly, there is a problem that a current necessary for the driver is detected and an accurate motor phase current cannot be detected.

  Furthermore, when the air blower is operated with a large air volume, the current flowing through the circuit is large (eg, 1.2 A). On the other hand, the current required for the driver is about 10 mA, which is a small proportion and does not affect the air volume. However, when operating with a small air volume, the current flowing in the circuit is small (about 30 mA), and the ratio of the current (10 mA) necessary for the driver is large. Therefore, the detected current includes a large error with respect to the current value corresponding to the actual air volume, and cannot be accurately controlled with respect to the air volume.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a ventilator that accurately detects a current flowing through a motor and accurately controls the air flow with respect to a target air flow.

  In addition, in the conventional blower that measures the motor current with the current detection unit and calculates the air volume as described above, the motor position is calculated from the output of the current detection unit. When the DC voltage for driving drops, the motor control is stopped immediately and the motor driving is stopped. However, once the control of the motor is stopped, it is necessary to completely stop the motor in order to drive the motor again, and it takes time to restart, which causes discomfort to the user. It was.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a ventilator that adjusts the rotational speed of a motor at the time of a momentary power failure and does not cause discomfort to the user at the time of the momentary power failure.

In order to achieve this object, the present invention is a ventilation device that can vary the air volume,
The ventilation device includes a motor for driving the blades and a control circuit for controlling the motor, and the control circuit includes two switching elements that are composed of an upper stage and a lower stage and perform opposite ON / OFF operations. Three arms connected in series with a DC voltage are connected in a three-phase bridge shape, and an inverter circuit that applies a three-phase PWM AC voltage to the motor, and the lower stage and negative potential side of each phase of the inverter circuit A shunt resistor inserted for each phase between the amplifier, an amplifier for amplifying the voltage across the terminals of the shunt resistor, a current detector for detecting the current of each phase flowing from the output of the amplifier to the motor, and the current detection A rotation detection unit that calculates the rotation speed and position of the motor based on the current detected by the unit, and the control circuit further comprises:
A target air volume calculating unit for calculating a target value of the air volume output by the ventilator, a current value of one phase among the current values of each phase detected by the current detecting unit, and a rotation calculated by the rotation detecting unit; The air volume calculation unit that compares the current value corresponding to the target air volume and the rotation speed, and the motor circuit by changing the duty of the inverter circuit based on the comparison result of the air volume calculation unit A speed control unit for controlling the number, and a voltage detection unit for detecting the drive voltage of the motor,
The target air volume calculation unit is configured to monitor the voltage value detected by the voltage detection unit, and to give an instruction to decrease the target air volume when the voltage value decreases by a predetermined deviation or more, thereby To achieve this goal.

  In the ventilator of the present invention, the control circuit includes amplification factor changing means for changing the amplification factor of the amplification unit, and the amplification factor changing unit inputs the air volume calculation unit based on the target air volume. The amplification unit is configured to switch the amplification factor for detecting the current value, thereby achieving the intended purpose.

  As described above, the present invention is a ventilator that can change the air volume, and the ventilator includes a motor that drives the blades and a control circuit that controls the motor, and the control circuit includes an upper stage. The three arms consisting of two switching elements that perform on / off operations that are in conflict with each other and connected in series to the DC voltage are connected in a three-phase bridge shape, and the AC voltage of the three-phase PWM system is connected to the motor. From the inverter circuit to be applied, the shunt resistor inserted for each phase between the lower stage and the negative potential side of each phase of the inverter circuit, the amplifier for amplifying the voltage across the terminals of the shunt resistor, and the output of the amplifier A current detection unit that detects a current of each phase flowing through the motor; and a rotation detection unit that calculates a rotation speed and a position of the motor based on the current detected by the current detection unit. A target air volume calculation unit that calculates a target value of the air volume output by the ventilator, a current value of any one of the current values detected by the current detection unit, and the rotation detection unit Based on the comparison result of the air volume calculation unit that inputs the rotation speed and compares the rotation speed with the current value corresponding to the target air volume, the duty of the inverter circuit is varied to change the motor A speed control unit for controlling the number of revolutions and a voltage detection unit for detecting the drive voltage of the motor, and the target air volume calculation unit monitors the voltage value detected by the voltage detection unit, and the voltage value is Since the instruction is made to reduce the target air volume when the deviation is more than a predetermined deviation, it is possible to directly detect only the current flowing in the motor winding. To detect It can become, ventilation power always kept constant, an effect of reducing a and wasted energy. In addition, it is possible to continue control without stopping the motor in the event of an instantaneous power failure, eliminating the need to stop the motor when there is a short time voltage fluctuation caused by an instantaneous power failure, etc. Play.

Installation drawing showing the ventilation device installed on the ceiling Block diagram showing the configuration of the control circuit of the ventilator Flow chart showing operation of the ventilator

  The ventilator according to claim 1 of the present invention is a ventilator capable of changing the air volume, and includes a motor for driving the blades and a control circuit for controlling the motor inside the ventilator. Is composed of an upper stage and a lower stage, and two switching elements that perform opposite ON / OFF operations are connected in series with a DC voltage, and three arms are connected in a three-phase bridge shape to generate a three-phase PWM AC voltage. An inverter circuit to be applied to the motor; a shunt resistor inserted for each phase between a lower stage and a negative potential side of each phase of the inverter circuit; an amplifying unit for amplifying a voltage between terminals of the shunt resistor; A current detection unit that detects a current of each phase flowing from the output of the unit to the motor, and a rotation detection unit that calculates the rotation speed and position of the motor based on the current detected by the current detection unit. The control circuit includes a target air volume calculation unit that calculates a target value of the air volume output from the ventilation device, a current value of any one of the current values detected by the current detection unit, and the rotation detection unit. Is input, and the air flow calculation unit that compares the rotation speed with the current value corresponding to the target air flow, and the duty of the inverter circuit is varied based on the comparison result of the air flow calculation unit. A speed control unit that controls the rotation speed of the motor; and a voltage detection unit that detects a drive voltage of the motor, and the target air volume calculation unit monitors a voltage value detected by the voltage detection unit, and When the voltage value decreases by a predetermined deviation or more, an instruction to decrease the target air volume is issued.

  As a result, only the current flowing through the motor winding can be directly detected, so that the current of the motor winding can be accurately detected, and the ventilation airflow can always be kept constant. Further, control can be continued without stopping the motor when the voltage fluctuates for a short time due to an instantaneous power failure or the like.

  In addition, the control circuit includes an amplification factor changing unit that changes the amplification factor of the amplification unit, and the amplification factor changing unit detects a current value input to the air volume calculating unit based on the target air volume. The amplification unit has a configuration for switching the amplification factor.

  This makes it possible to change the magnitude of the amplification factor according to the target air volume, accurately detect the current flowing in the motor winding, and keep the ventilation air volume constant even when the target air volume is small. Can do.

  The control circuit includes an amplification factor changing unit that changes the amplification factor of the amplification unit, and the amplification factor changing unit inputs the current amount to the air volume calculation unit based on the current detected by the current detection unit. It is good also as a structure which switches the gain of the said amplification part for detecting an electric current value.

  As a result, the size of the amplification changing means can be changed according to the current detected by the current detection unit, and the current flowing in the motor winding can be accurately detected. Even when the target air volume is small, the ventilation air volume is small. Can always be kept constant.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

(Embodiment 1)
As an embodiment of the ventilator of the present invention, a ventilator provided on a ceiling in a building will be described.

  The ventilator according to the present embodiment takes advantage of the characteristics of the DC motor, performs control from a low speed to a high speed, and covers a single air ventilator from a low air volume to a large air volume.

  As shown in FIG. 1, the ventilator of the present embodiment is installed in the ceiling 2 of the room 1 and has a suction port 3 a below the main body 3. An adapter 4 is provided on the side surface of the main body 3 and is connected to an exhaust port (not shown) provided on an outer wall or the like through an exhaust duct 5. Inside the main body 3, a blade 7 and a sensorless brushless DC motor 8 that rotates the blade 7 are provided, and a suction port 3a is provided with a louver 9 that covers the suction port 3a. The louver 9 has a vent through which indoor air passes. A control circuit 10 for driving the sensorless brushless DC motor 8 is disposed inside the main body 3 of the ventilation device. A remote control device 11 (a switch formed by integrating a power on / off switch 11a and a fan notch setting switch 11b) is disposed on an indoor wall and connected to the control circuit 10.

  FIG. 2 is a block diagram showing the configuration of the control circuit 10 of the main body 3 of the ventilation device. In FIG. 2, the AC voltage supplied from the commercial power supply 12 is DC converted by the AC / DC converter circuit 13, smoothed by the smoothing capacitor 14, and applied to the inverter circuit 15. The inverter circuit 15 electrically connects the six switching elements to drive the sensorless brushless DC motor 8. The sensorless brushless DC motor 8 includes a stator 16 wound with a winding and a rotor 17 having a magnet.

  A shunt resistor 18 is inserted for each phase between the lower stage of each phase of the inverter circuit 15 and the negative potential side. The amplifying unit 19 amplifies the potential difference between both ends of the shunt resistor 18 generated by the current flowing through the shunt resistor 18. From the output of the amplification unit 19, the current detection unit 20 detects the current of each phase flowing through the sensorless brushless DC motor 8. The rotation detection unit 25 calculates the rotation speed and position of the sensorless brushless DC motor 8 based on the current detected by the current detection unit 20.

  The air volume calculating unit 24 compares the current detected by the current detecting unit 20 with the air volume calculated based on the rotation speed detected by the rotation detecting unit 25 with respect to the target air volume Qs, and determines whether the air volume is high or low. to decide.

  The target air volume calculating unit 21 calculates the target air volume Qs corresponding to the setting of the fan notch setting switch 11b, and instructs the air volume calculating unit 24 of the target air volume Qs.

  The amplification factor changing means 22 receives the target air volume Qs calculated by the target air volume calculator 21 and changes the amplification factor of the amplifying unit 19 of a predetermined phase according to the magnitude of the target air volume Qs.

  The speed control unit 23 outputs a duty to the inverter circuit 15 to vary the rotation speed of the sensorless brushless DC motor 8.

  The sensorless brushless DC motor 8 outputs the necessary air volume by changing the rotation speed.

  Further, the control circuit 10 includes a voltage detection unit 26 that detects the voltage of the smoothing capacitor 14 that is the drive voltage of the sensorless brushless DC motor 8. The voltage detection unit 26 outputs the detected voltage value to the target air volume calculation unit 21. The target air volume calculation unit 21 monitors the voltage value detected by the voltage detection unit 26, and reduces the target air volume Qs when the voltage value decreases by a predetermined deviation or more.

  Hereinafter, the operation of the ventilation device of the present embodiment will be described with reference to FIG.

  A user operates the remote controller 11 to operate the ventilator to turn on the main body 3 of the ventilator, and sets the fan notch setting switch 11b to, for example, a weak notch. Then, power is applied to the control circuit 10, and the target air volume calculating unit 21 instructs the target air volume Qs to the air volume calculating unit 24 according to the setting of the fan notch setting switch 11b.

  Further, the target air volume calculation unit 21 determines that the voltage of the smoothing capacitor 14 has been reduced due to an instantaneous power failure when the signal V from the voltage detection unit 26 falls below a predetermined threshold value V1. Then, the target air volume Qs is reduced to, for example, the minimum air volume Qmin regardless of the setting of the fan notch setting switch 11b. As a result, when the instantaneous power failure occurs, the target air volume Qs decreases to the minimum air volume Qmin, and the voltage drop of the smoothing capacitor 14 becomes gentle. Therefore, the control of the sensorless brushless DC motor 8 can be continued until the instantaneous power failure is restored. It becomes possible.

  When the signal V from the voltage detection unit 26 returns to the predetermined threshold value V1 or more, the target air volume calculation unit 21 performs an operation of returning to the target air volume Qs according to the setting of the fan notch setting switch 11b.

  When the target air volume Qs is determined, the amplification factor of any one of the three phases is changed by the amplification factor changing means 22 in accordance with the target air volume Qs. The speed control unit 23 outputs a duty to the inverter circuit 15 based on the value determined by the target air volume Qs.

  When the duty is output to the inverter circuit 15, the six switching elements are sequentially turned on to drive the sensorless brushless DC motor 8. When the sensorless brushless DC motor 8 is driven, a current flows through the shunt resistor 18. The amplifying unit 19 amplifies the potential difference between both ends of each shunt resistor 18. The current detection unit 20 detects a potential difference between both ends of each amplified shunt resistor 18 and detects a current (winding current) flowing through the motor winding for each phase based on the potential difference. Two phases of the detected winding current are input to the rotation detector 25. As will be described in detail later, the remaining winding current for one phase is input to the air volume calculation unit 24. The rotation detector 25 calculates the rotation speed and position of the sensorless brushless DC motor 8 from the winding currents for two phases.

  Next, the air volume calculation unit 24 calculates the current output air volume Qn from the current value for one phase detected by the current detection unit 20 and the rotation speed detected by the rotation detection unit 25. Then, the air volume calculation unit 24 compares the calculated output air volume Qn with the target air volume Qs. When the output air volume Qn is smaller than the target air volume Qs, the air volume calculator 24 instructs the speed controller 23 to output a large duty. When the output air volume Qn is larger than the target air volume Qs, the air volume calculation unit 24 instructs the speed control unit 23 to output a smaller duty, and controls to reduce the deviation between the output air volume Qn and the target air volume Qs. Will be.

  Here, when the output air volume Qn is sufficiently small with respect to the rated air volume, the current flowing through the shunt resistor 18 is small, and it is difficult for the current detection unit 20 to accurately detect the current flowing through the winding current. Therefore, when the target air volume Qs is smaller than the predetermined air volume Qa, the amplification factor changing means 22 performs a process of increasing the amplification factor of the amplifier 19 for detecting the current value input to the air volume calculator 24. The predetermined air volume Qa is an air volume value stored in advance. This Qa is set to a value that is sufficiently small with respect to the rated air volume and that the current detection unit 20 cannot accurately detect the winding current unless the amplification factor is switched and detected.

  In the ventilator configured as described above, the current flowing through the sensorless brushless DC motor 8 has a shunt resistor 18 inserted between the lower stage of each phase of the inverter circuit 15 and the negative potential side for each phase, and the current flowing through the shunt resistor 18. The winding current can be detected with high accuracy by detecting. Further, the winding current can be accurately detected by changing the amplification factor of any one of the phases by the amplification factor changing means 22. Accordingly, ventilation from a small air volume to a large air volume utilizing the characteristics of the DC motor can be performed with one main body.

  Further, the target air volume calculation unit 21 stores therein a lower limit value (threshold value) V1 of the power supply voltage. The target air volume calculation unit 21 determines that an instantaneous power failure has occurred when the signal V from the voltage detection unit 26 becomes smaller than the threshold value V1. When it is determined that an instantaneous power failure has occurred, an instruction to lower the target air volume Qs is given. Then, by reducing the target air volume Qs, the voltage drop of the smoothing capacitor 14 becomes gentle, so that the control of the sensorless brushless DC motor 8 can be continued until the instantaneous power failure is restored. That is, there is no need to stop the sensorless brushless DC motor 8, and a ventilation device that does not give the user unpleasantness can be configured.

  In the present embodiment, the gain changing means 22 is configured to switch the gain corresponding to the target air volume Qs. However, the gain may be switched based on the current value detected by the current detector 20. .

  In this embodiment, the sensorless brushless DC motor 8 is used. However, the gain changing means 22 for switching the gain uses the output of the magnetic sensor to determine the relative position of the rotor 17 with respect to the stator 16. It is also possible to apply to a brushless DC motor that detects the position. That is, the effect is the same in the configuration in which the shunt resistor 18 is connected to any one phase and the amplification factor changing unit 22 switches the amplification factor of the amplification unit 19 that amplifies the potential difference between both ends of the shunt resistor 18.

  Further, in the present embodiment, the predetermined threshold is set to only V1 with respect to the output V from the voltage detection unit. However, by providing a plurality of predetermined thresholds, the air volume is changed stepwise. Good.

  The ventilation device attached to a building according to the present invention is widely useful in products that can obtain an air volume within a predetermined time regardless of duct resistance and external wind pressure.

DESCRIPTION OF SYMBOLS 1 Indoor 2 Ceiling back 3 Main body 4 Adapter 5 Exhaust duct 7 Blade 8 Sensorless brushless DC motor 9 Louver 10 Control circuit 11 Remote control device 11b Fan notch setting switch 12 Commercial power supply 13 AC / DC conversion circuit 14 Smoothing capacitor 15 Inverter circuit 16 Stator 17 Rotation Child 18 Shunt resistor 19 Amplifying unit 20 Current detecting unit 21 Target air volume calculating unit 22 Amplification rate changing means 23 Speed control unit 24 Air volume calculating unit 25 Rotation detecting unit 26 Voltage detecting unit

Claims (3)

A ventilation device with variable air volume,
The ventilation device includes a motor for driving the blades and a control circuit for controlling the motor.
In the control circuit, three arms composed of an upper stage and a lower stage and two switching elements that perform opposite ON / OFF operations are connected in series to a DC voltage are connected in a three-phase bridge shape, and three-phase PWM An inverter circuit for applying an AC voltage of the method to the motor;
A shunt resistor inserted for each phase between the lower stage and the negative potential side of each phase of this inverter circuit,
An amplifying unit for amplifying the voltage across the terminals of the shunt resistor, a current detecting unit for detecting a current of each phase flowing from the output of the amplifying unit to the motor,
A rotation detector that calculates the rotational speed and position of the motor based on the current detected by the current detector;
Further, the control circuit includes:
A target air volume calculator for calculating a target value of the air volume output by the ventilator;
The current value of any one phase detected by the current detection unit and the rotation number calculated by the rotation detection unit are input, and the current value corresponding to the target air volume is compared with the rotation number. An air volume calculation unit;
Based on the comparison result of the air volume calculation unit, the speed control unit that controls the rotation speed of the motor by varying the duty for the inverter circuit;
A voltage detector for detecting the driving voltage of the motor;
The target air volume calculation unit monitors the voltage value detected by the voltage detection unit, and gives an instruction to decrease the target air volume when the voltage value decreases by a predetermined deviation or more. The control circuit includes amplification factor changing means for changing the amplification factor of the amplification unit,
The ventilation device according to claim 1, wherein the amplification factor changing means switches the amplification factor of the amplification unit for detecting a current value input to the air volume calculation unit based on the target air volume. The control circuit includes amplification factor changing means for changing the amplification factor of the amplification unit,
The ventilation device according to claim 1, wherein the amplification factor changing means switches the amplification factor of the amplification unit for detecting a current value input to the air volume calculation unit based on a current detected by the current detection unit.

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