JP6221057B2 - Ventilation equipment - Google Patents

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).

JP 2002-165477 A

  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 through 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.

  Further, in the case of a blower with a large air volume, in order to suppress the generation of noise, the blade diameter is increased to increase the air volume per rotation, and a predetermined air volume is generated without increasing the rotation speed. When such a blower with a large blade diameter is operated with a low air volume, the number of rotations tends to be small. When operating with a low air volume, it is difficult to achieve a difference in the number of revolutions, so the air volume cannot be accurately controlled.

  Therefore, the present invention solves the above-described conventional problems, and accurately detects the current flowing through the motor and uses the modulation rate of the voltage applied to the motor without using the rotational speed to achieve the target air volume. An object of the present invention is to provide a ventilation device that performs air flow control with high accuracy.

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 perform upper and lower stages and perform opposite ON / OFF operations. Three arms connected in series with a DC voltage are connected in a three-phase bridge shape, an inverter circuit that applies a three-phase PWM voltage to the motor, and a lower stage and a negative potential side of each phase of the inverter circuit A shunt resistor inserted for each phase in between, 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, and the current detecting unit A rotation detection unit that calculates the rotation speed and position of the motor based on the current detected in step, and a speed control unit that controls the rotation speed of the motor by varying the duty of the inverter circuit. Further, the control circuit inputs the current value of any one of the current values of each phase detected by the current detection unit and the modulation rate of the voltage applied to the motor, and the current value / modulation rate And the air volume calculation unit that compares the current value and modulation rate corresponding to the target air volume, and based on the comparison result of this air volume calculation unit, the modulation rate is increased or decreased to the target air volume and output to the speed control unit In this way, the intended purpose is achieved.

In the ventilator of the present invention, the control circuit includes an amplification factor changing means for changing the amplification factor of the amplifying unit. The amplification factor changing means inputs the target air volume, and the magnitude of the target air volume. The amplification factor of the amplifying unit is changed according to the above, 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 lower arm is composed of two switching elements that perform opposite ON / OFF operations, connected in series to a DC voltage, and three arms are connected in a three-phase bridge shape to apply a three-phase PWM voltage to the motor. Inverter circuit, a shunt resistor inserted for each phase between the lower stage and the negative potential side of each phase of the inverter circuit, an amplifying unit for amplifying the voltage across the terminals of the shunt resistor, and an output of the amplifying unit from the motor A current detection unit that detects a current of each phase flowing through the motor, a rotation detection unit that calculates the rotation speed and position of the motor based on the current detected by the current detection unit, and an inverter circuit. A speed control unit that controls the number of rotations of the motor by varying the motor, and the control circuit applies a current value of any one of the current values detected by the current detection unit to the motor. The air volume calculation unit that compares the current value / modulation rate with the current value / modulation rate corresponding to the target air volume, and the target air volume based on the comparison result of the air volume operation unit. Since the modulation rate is increased and decreased so that the output is output to the speed control unit, only the current flowing through the motor winding can be directly detected. It becomes possible to detect the current of the line, and there is an effect that the ventilation air volume is always kept constant and useless energy can be reduced.

  In addition, in a large air volume type with a large blade diameter, when operating with a low air volume, the rotational speed tends to be small, and when operating with a low air volume, a difference in rotational speed is less likely to occur. Even in such a case, a difference in the modulation rate of the voltage applied to the motor is likely to occur. For this reason, by using the modulation rate of the voltage applied to the motor without using the rotation speed, even when the rotation speed difference is small, the modulation rate of the voltage applied to the motor is used to achieve the target air volume. The air volume control can be performed with high accuracy.

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 the ventilator includes a motor for driving the blades and a control circuit for controlling the motor. Is composed of an upper stage and a lower stage, and three switching elements that perform opposite ON / OFF operations are connected in series with a DC voltage in a three-phase bridge configuration, and the three-phase PWM voltage is An inverter circuit to be applied to the motor; a shunt resistor inserted for each phase between the lower stage and the negative potential side of each phase of the inverter circuit; an amplifying unit for amplifying the voltage across the terminals of the shunt resistor; For the inverter circuit, a current detector that detects current of each phase flowing from the output to the motor, a rotation detector that calculates the rotation speed and position of the motor based on the current detected by the current detector, and the inverter circuit A speed control unit configured to control the number of rotations of the motor by varying a duty; and the control circuit further includes a current value of any one phase among current values detected by the current detection unit, and the motor Based on the comparison result of the air volume calculation unit, the current value / modulation rate and the current value / modulation rate corresponding to the target air volume are compared. The modulation rate is increased or decreased so as to reach the target air volume and output to the speed control unit.
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.
For large air volume types with large blade diameters, by using the modulation rate of the voltage applied to the motor without using the rotation speed, even when the rotation speed difference is small, the air volume control can be performed accurately with respect to the target air volume. Can be performed.

Further, the control circuit includes an amplification factor changing means for changing the amplification factor of the amplifying unit, the amplification factor changing unit inputs the target air volume, and the amplification unit of the amplifying unit according to the size of the target air volume . It has a configuration for changing the amplification factor.

  This makes it possible to change the size of the amplification changing means 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. be able to.

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 is provided in the air volume calculating unit when the target air volume is smaller than a predetermined air volume. the current value input may be configured to raise the amplification factor of the amplifying section in order to be detected by the current detection unit.
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 calculation unit 24 compares the current detected by the current detection unit 20 with the air volume calculated based on the modulation rate of the voltage applied to the motor with respect to the target air volume Qs, and determines whether the air volume is high or low. To do.
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.
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. 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 modulation rate determined by the air volume calculation unit 24.

  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 modulation rate of the voltage applied to the motor. Specifically, for example, the relationship between the modulation rate of the voltage applied to the motor at the target air volume Qs and the motor current is stored in advance, and the current output air volume Qn is calculated backward based on this relationship. That is, the motor current (specified motor current) at the target air volume Qs is obtained with respect to the modulation rate of the voltage applied to the motor. The calculated specified motor current value is compared with the current value for one phase detected by the current detection unit. If the specified motor current value is smaller, the output air volume Qn is larger than the target air volume Qs (too much). to decide. On the other hand, if the specified motor current value is larger, it is determined that the output air volume Qn is smaller (insufficient) than the target air volume Qs. If the specified motor current value is equal to the current value for one phase detected by the current detector, the output air volume Qn is calculated to be equal to 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 modulation rate. When the output air volume Qn is larger than the target air volume Qs, the air volume calculating unit 24 instructs the speed control unit 23 to output a small modulation rate so as to reduce the deviation between the output air volume Qn and the target air volume Qs. Will be controlled.

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.
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.

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 16 Stator 17 Rotor 18 Shunt Resistance 19 Amplifier 20 Current detector 21 Target air volume calculator 22 Amplification rate changing means 23 Speed controller 24 Air volume calculator 25 Rotation detector

Claims (3)

A ventilation device with variable air volume,
Inside the ventilator,
A motor for driving the blades;
A control circuit for controlling this motor is provided,
The control circuit includes
Three arms consisting of an upper stage and a lower stage and two switching elements that perform opposite ON / OFF operations connected in series to a DC voltage are connected in a three-phase bridge shape, and a three-phase PWM voltage is applied to the motor. An inverter circuit to be applied;
A shunt resistor inserted for each phase between the lower stage of each phase of the inverter circuit and the negative potential side;
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;
A rotation detection unit that calculates the rotation speed and position of the motor based on the current detected by the current detection unit, and a speed control unit that controls the rotation speed of the motor by varying the duty of the inverter circuit;
Further, the control circuit includes:
One of the current values of each phase detected by the current detection unit and the modulation rate of the voltage applied to the motor are input, and this current value / modulation rate and the target air volume are handled. An air volume calculation unit that compares the current value and the modulation rate, and a ventilation device that increases and decreases the modulation rate so as to reach the target air volume based on the comparison result of the air volume calculation unit and outputs the result to the speed control unit. 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 inputs the target air volume and changes the amplification factor of the amplifying unit according to the target air volume . The control circuit includes amplification factor changing means for changing the amplification factor of the amplification unit,
The amplification factor changing means increases the amplification factor of the amplifying unit in order to detect the current value input to the air volume calculating unit by the current detecting unit when the target air volume is smaller than a predetermined air volume. The ventilator according to 1.