JP2560812B2 - Blower control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling an electric motor driven blower controlled by an inverter, and more particularly to a method for controlling a blower for cleaning foreign matters in a duct.

[Conventional technology]

In this type of air blower that performs constant pressure control, a considerable amount of foreign matter may be present inside the duct while the blower is stopped, and in that case, the foreign matter was not floating and adhered to the inner circumference of the duct. It often exists in a state.

Since the pressure constant control as shown in FIG. 2 is performed in this adhered state, even if the pressure is started at a normal target set pressure value, these foreign substances cannot be discharged to the outside at that pressure.

For this reason, conventionally, the constant pressure control during manual operation is periodically disabled, and the inverter is switched to manual adjustment to rotate the blower drive motor at high speed, or the blower drive motor is manually operated from the inverter. By switching to commercial high speed operation with commercial power source,
Cleaning work was performed to discharge foreign matter.

[Problems to be Solved by the Invention]

However, according to the cleaning operation described above,
Since the work of switching the inverter to the manual adjustment, the work of switching the blower driving electric motor to the commercial power source, and the like must be performed manually, it is troublesome and the labor cost for the work is great.

Also, when returning from high-speed operation to normal constant pressure control operation, a large undershoot due to PI control occurred, causing a temporary pressure drop.

Further, if the normal constant pressure control operation is continued without forgetting this cleaning work that should be performed regularly, foreign matter in the duct will adhere to the duct more frequently, which will cause the duct to be clogged.

Therefore, an object of the present invention is to perform a cleaning operation for removing foreign matter in the duct automatically in the blower control method, and to significantly reduce the PI control when returning from the cleaning operation to the normal constant pressure control operation. Another object of the present invention is to provide a blower control method that does not cause the undershoot.

[Means for solving the problem]

To achieve the above object, the present invention detects the discharge pressure or suction pressure of a blower with a pressure sensor, compares the detected pressure with a preset target pressure by a comparator, and calculates the PI output of this comparator. In the control method of the blower that controls the blower drive motor inverter based on the result calculated by the controller, and controls the discharge pressure or the suction pressure to a constant value, it is forced to operate for a certain period of time at startup and / or after every lapse of a predetermined time after startup. At the same time, the blower is automatically operated at high speed, and the pressure detection value input to the comparator is maintained at zero during the automatic high speed operation.

Alternatively, the discharge pressure or suction pressure of the blower is detected by a pressure sensor, the detected pressure is compared with a preset target pressure by a comparator, and the blower is driven based on the result of calculating the comparator output by the PI calculator. In the control method of the blower for controlling the inverter for the electric motor to control the discharge pressure or the suction pressure to be constant, at the time of start-up and / or after a lapse of a predetermined time after start-up, the blower is automatically driven at a high speed for a fixed time, and The I component of PI control in the PI calculator may be held at zero during the automatic high-speed operation.

[Operation] According to the blower control method of the present invention, by providing a microcomputer (hereinafter, referred to as a CPU) having a cleaning sequence program incorporated therein in the inverter, a predetermined time elapses at the time of startup and / or after the startup. The blower drive motor is forcibly operated at a high speed for a certain period of time after each operation, and the rest of the period is controlled based on the speed command after normal pressure calculation. It is possible to perform constant pressure control, and during high-speed operation for cleaning, by controlling the detection value input from the pressure detector to the comparator via the pressure sensor to zero, the PI calculator The output becomes saturated at the upper limit, and when returning to normal pressure control operation, it operates so as to settle from the upper limit pressure value to the target pressure control value, and PI control is performed. Significant undershoot does not occur that.

Alternatively, during high-speed operation for cleaning, by controlling the I component of PI control (for example, the condenser) to zero, the output of the PI calculator does not saturate at the lower limit. The normal pressure control operation can be restored only by the undershoot of.

〔Example〕

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram of a blower drive device showing an embodiment of the present invention. In FIG. 1, 10 is a pressure setting device,
Reference numeral 12 is a pressure detector, 14 is a switch, and 16 is a comparator. The output of the pressure setting device 10 is input to the comparator 16, and the output of the pressure detector 12 is input via the switch 14. The output of the comparator 16 is input to the inverter (INV) 20 via the PI calculator 18, and the output of the inverter 20 is applied to the electric motor 24 for the blower 26 in the duct 28. Inverter
The signal line 22 from the CPU (not shown) in 20 is connected to the switch 1
Connected to 4 control terminals. The output of the pressure sensor 30 provided on the duct 28 is input to the pressure setter 12.

Next, the operation of this embodiment configured as described above will be described.

During normal pressure control operation, the switch 14 is activated by the signal sent from the CPU in the inverter 20 via the signal line 22.
Is closed, and the target pressure set by the pressure detector 10 and the actual pressure detected by the pressure detector 12 via the pressure sensor 30 are input to the comparator 16. The comparison result between this target pressure and the actual pressure is calculated by the PI calculator 18,
A speed command is given to the inverter 20. As a result, the inverter 20 performs constant static pressure control operation so that the electric motor 24 for the blower 26 reaches the target pressure based on the speed command.

At the time of start-up and / or after a lapse of a predetermined time from start-up, the CPU in the inverter 20 controls the inverter 20 so that the electric motor 24 operates at a high speed for a certain time regardless of the speed command from the PI calculator 18 described above. The cleaning operation for discharging foreign matter is performed. At this time, if the undershoot preventing function according to the present invention is not operated, a pressure change as shown in FIG. 3 is caused. That is, at startup for a certain time
While the electric motor 24 is rotating at high speed for t ₁ and air is blown at a high pressure to perform foreign matter discharging operation (indicated by in FIG. 3)
Indicates that the actual pressure value detected by the pressure detector 12 via the pressure sensor 30 is higher than the set pressure value of the pressure setter 10 for a long time, so the operation output of the PI operator 18 is saturated to the lower limit. However, a large amount of undershoot occurs when returning to the normal pressure control operation, causing a temporary pressure drop (indicated by in FIG. 3). After that, the same pressure change occurs every predetermined time t ₂ .

In order to prevent such a large undershoot due to PI control when returning to the normal pressure control operation, in the present embodiment, the comparator 16 is operated during the cleaning operation control period in which the blower 26 is forcibly and automatically operated at high speed. The switch 14 is opened by a signal sent from the CPU in the inverter 20 via the signal line 22 in order to keep the pressure detection value input to the zero. As a result, the calculation output of the PI calculator 18 saturates at the upper limit, so when returning to normal pressure control operation, the target pressure settles from the upper limit to the set target pressure as shown in the pressure change diagram of FIG. No significant undershoot.

Further, as a method of preventing the occurrence of a large undershoot, although not shown, during the cleaning operation control period in which the blower 26 is forcibly operating at high speed automatically, the I component (eg, capacitor) of the PI calculator 18 is set to the inverter 20. A method of removing and invalidating by a signal sent from the internal CPU via the signal line 22 may be used. As a result, the calculation output of the PI calculator 18 does not saturate at the lower limit, and normal pressure control operation can be started with only a slight undershoot.

〔The invention's effect〕

As is clear from the above-mentioned embodiment, according to the present invention,
During the fixed time after startup and / or the fixed time after the lapse of a predetermined time after startup, forced high-speed rotation control is performed regardless of the normal static pressure constant control, and the forced high-speed rotation control period is compared. The high-speed operation of the blower by this high-speed rotation is achieved by pre-programming the CPU in the inverter so that the pressure detection value input to the device is held at zero or the I component of PI control is held at zero. It automatically cleans the inside of the duct and prevents undershoot due to PI control after cleaning to enable constant static pressure control.

Therefore, unlike the prior art, cleaning can be performed without human intervention, so that troublesome work can be eliminated and labor cost can be greatly restricted.

Also, in applications such as dust exhaust blowers, dust can be discharged even less during normal operation,
In order to prevent dust clogging in the duct due to start-up or occasional catching, etc., conventionally, high speed operation was used constantly, but if applied to this, power consumption is saved to the same level as general exhaust blowers. There is an effect that can be done.

Furthermore, if the present invention is used in a pump or the like, it can be expected to be effective in discharging red rust generated in a pipe.

[Brief description of drawings]

FIG. 1 is a block diagram of a blower drive device showing an embodiment of the present invention, FIG. 2 is a diagram showing a pressure change in a duct of a conventional blower drive device without forced high speed operation, and FIG. 3 is a forced high speed operation. The figure which shows the pressure change in the duct of the blower drive device which has an operation but does not have an undershoot prevention function.
The figure is a diagram showing the pressure change in the duct of the blower drive device of the present invention having both the forced high speed operation and the undershoot preventing function. 10 …… Pressure setter, 12 …… Pressure detector, 14 …… Switch, 16 …… Comparator 18 …… PI calculator, 20 …… Inverter, 22 …… Signal line, 24
...... Motor 26 …… Blower, 28 …… Duct, 30 …… Pressure sensor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G05D 16/20 G05D 16/20 D

Claims (2)

(57) [Claims] 1. A blower discharge pressure or suction pressure is detected by a pressure sensor, the detected pressure is compared with a preset target pressure by a comparator, and the output of this comparator is calculated by a PI calculator. Based on the blower control method, which controls the inverter for the blower drive motor based on this, to control the discharge pressure or suction pressure at a constant level, the blower is automatically driven at high speed for a certain period of time at startup and / or after a lapse of a predetermined time after startup. The blower control method is characterized in that the pressure detection value input to the comparator is held at zero during automatic high speed operation. 2. A discharge sensor or a suction pressure of a blower is detected by a pressure sensor, the detected pressure is compared with a preset target pressure by a comparator, and the output of this comparator is calculated by a PI calculator. Based on the blower control method, which controls the inverter for the blower drive motor based on this, to control the discharge pressure or suction pressure at a constant level, the blower is automatically driven at high speed for a certain period of time at startup and / or after a lapse of a predetermined time after startup. In addition, the blower control method is characterized in that the I component of the PI control in the PI calculator is held at zero during the automatic high speed operation.