JPH02168884A - Phase controlling method for induction motor - Google Patents

Abstract

PURPOSE:To enable the rotational frequency of a room interior fan motor to be quickly turned into set rotational frequency by varying a rotational frequency detecting time interval according to a difference between present rotational frequency and the set rotational frequency. CONSTITUTION:On the phase control of a room interior fan motor 3, its rotational frequency is set, and the phase control for setting rotational frequency at specified time intervals, as the set rotational frequency is performed. In this case, when a difference between present rotational frequency and the set rotational frequency is greater than a boundary value, then a rotational frequency detecting time is shortened, and when the difference between the present rotational frequency and the set rotational frequency is less than the boundary value, then the rotational frequency detecting time is lengthened. As a result, the rotational frequency of the room interior fan motor 3 can be quickly turned into the set rotational frequency.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for controlling the phase of an indoor fan motor (AC induction motor) of a split near conditioner, etc. The present invention relates to a phase control method for an induction motor that improves output characteristics (followability).

[Conventional Example] In recent years, microcomputers have been used to control air conditioners and the like and have various functions. This type of air conditioner has an indoor temperature sensor, a heat exchanger temperature sensor, etc. using a thermistor, etc., and drives the compressor according to the difference between a set value by a remote controller, etc. and a detected value by these sensors. , drives indoor fans and outdoor fans,
The indoor temperature is brought closer to the set value to maintain a more comfortable environment.

By the way, an AC induction motor is used for the indoor fan motor, and the rotation speed of this induction motor is controlled by a phase control method. During the phase control, control is performed according to the flowchart shown in FIG. 3, for example.

First, when controlling the rotation of the indoor fan motor, pulses corresponding to the rotation speed are output from the Hall element, and the pulses are detected and counted by the microcomputer of the indoor unit control section (step ST). Then, for a predetermined period of time (
The counting operation is performed at Tc intervals (rotation speed detection time) (step 5T2), and the calculation process of the rotation speed NDATA of the indoor fan motor is performed from this count value (step 5T3).

Furthermore, in order to set the calculated rotation speed NDATA as the set rotation speed N5et of the indoor fan motor, which is set according to the operation of a remote controller, etc., the rotation speed is detected (Tc time).
Phase control is performed to change the conduction angle of the indoor fan motor by a fixed amount dθ each time (step 5T4). Then, the process returns to step STI and the above-described operation is repeated.

In this way, based on the rotation speed NDATA of the indoor fan motor detected at a certain rotation speed detection time Tc, the conduction angle is changed by a certain amount dO, and by repeating this, the rotation speed NDATA of the indoor fan motor is set. Rotation speed N
I'm trying to get it closer to 5et.

[Problems to be Solved by the Invention] However, in the above-mentioned induction motor phase control method, the rotation speed NDA of the indoor fan motor that is currently rotating
The larger the difference between TA and the newly set rotation speed N set by operating a remote control, etc., the greater the indoor fan motor rotation speed N DATA becomes.
There was a problem that it took a long time to reach 5et. That is, the conduction angle of the indoor fan motor is maintained for a predetermined time Tc.
This is because only a fixed amount dO can be changed each time.

This invention was made in view of the above problems, and its purpose is to improve the rotation speed NDA of an indoor fan motor (induction motor).
It is an object of the present invention to provide a phase control method for an induction motor that allows TA to quickly reach a set rotational speed N set.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention, when controlling an induction motor of an indoor fan motor to a set rotation speed, uses the rotation speed detected at predetermined time intervals and the set rotation speed. Based on this, the conduction angle of the induction motor is changed by a predetermined amount d every time the rotation speed is detected.
A phase control method for an induction motor in which the rotation speed of the induction motor is changed by θ to the set rotation speed in stages, The gist is that the rotation speed detection time interval is made variable.

Moreover, the gist of the phase control method for an induction motor of the present invention is that the predetermined time is shortened when the difference between the current rotation speed of the induction motor and the set rotation speed becomes large.

[Function] According to the above method, when controlling the phase of the induction motor, its rotation speed is set, and the rotation speed is set for a predetermined period of time (rotation speed detection time T).
c) Set the rotation speed ND^a9 at the interval to the rotation speed N5e
Phase control with t is performed. Here, the current rotation speed N
The difference between DATA and its set rotation speed N set is the boundary value S
c, the rotation speed detection time Tc is T”
f (<Tc), and the number of pulses obtained by the induction motor is reduced.

Therefore, the number of pulses is multiplied by a predetermined value n (>1) to more accurately calculate the current rotation speed. Also,
When the difference between the current rotation speed NDATA and the set rotation speed N5et is smaller than the boundary value Sc, the rotation speed detection time Tc is changed to Tn (>Tf).

In this way, when the difference between the current rotational speed NDATA of the induction motor and the set rotational speed Ns is large, the rotational speed detection time Tc is shortened, so when controlling the phase of the induction motor, the rotational speed NDATA is It is possible to more quickly and accurately approach the set rotational speed N set.

[Example] Embodiments of the present invention will be described below based on the drawings.

In Fig. 1, this air conditioner includes an indoor temperature sensor 1 that detects the indoor temperature, a heat exchanger temperature sensor 2 that detects the temperature of the heat exchanger, and an indoor temperature sensor 2 that detects the temperature of the heat exchanger. A fan motor (AC induction motor) 3, a motor drive unit 4 that drives the indoor fan motor 3, and a pulse signal for detecting the rotation speed of the indoor fan motor 3 are inputted and received by a receiving unit (not shown). An indoor control device that controls the rotation of the indoor fan motor 3 at a set rotation speed N set based on a remote control signal, etc., and outputs a control signal for controlling a refrigeration cycle including a compressor, a four-way valve, etc. to an outdoor control device (not shown). (microcomputer) 5
is provided.

The motor drive unit 4 also has an AC power supply 6 that supplies a voltage to be applied to the indoor fan motor 3, and a signal from the indoor control device 5 as a trigger to apply conduction of the AC power supply 6 to the indoor fan motor 3. A facing thyristor 7 is provided. Note that the indoor control device 5 is equipped with a memory that stores a control program and the like shown in FIG.

Next, a method for controlling the phase of an induction motor applied to the indoor fan motor of the air conditioner having the above configuration will be explained based on the flowchart shown in FIG. Note that the rotation speed NDATA of the indoor fan motor 3 is detected every rotation speed detection time Tc,
It is assumed that the conduction angle can be changed by a constant amount dθ based on the detected rotational speed NDA/T^ and the set rotational speed N5et.

First, when the indoor fan motor 3 rotates, a pulse signal corresponding to the rotation speed is output from a Hall element (not shown), and the microcomputer in the indoor control unit 5 detects and counts the pulse signal ( Step 5
TIO). The count is the above time Tc (for example, 2 seconds)
(Step 5T11), and the rotation speed N of the indoor fan motor 3 is determined from the pulse count value within that time Tc.
DATA is calculated (step 5T12).

Subsequently, the rotation speed detection time Tc becomes Tf (for example, 1 second <
Tc) is determined (step 5T1).
3). Here, initially, the rotation speed detection time Tc remains unchanged (for example, 2 seconds), but in the step described later, the value Tc is changed to Tf (for example, 1 second < Tc) or Tn (>
Tf). When the rotation speed detection time Tc is Tf, the number of count pulses is small, so the rotation speed NDATA calculated above is n×NDATA (n (for example, 2
)> an integer of 1) (step 5T14). However, since the number of count pulses is initially large during the rotational speed detection time Tc, the process of step 5T14 is not performed. If the rotational speed detection time Tc is shortened to '1゛f, the number of count pulses will decrease and it may become impossible to calculate the accurate rotational speed.
The number of count pulses at f is multiplied by n.

Subsequently, a difference calculation process is performed between the rotation speed N DATA calculated above and the set rotation speed N5et, and l N set
-N DATAI≧Sc (predetermined value, boundary value) is determined (step 5T15). If the difference in rotation speed is greater than SC, the indoor fan motor 3
The rotation speed detection time to obtain the rotation speed NDATA is Tf
(Step 5T16), and on the other hand, the difference in rotation speed is S
If the rotation speed detection time for obtaining the rotation speed NDATA of the indoor fan motor 3 is Tn (<T
c: Note that there is a relationship of Tn=nXTf) (step 5T17). In other words, the settings can be changed by operating a remote control, etc., and the indoor fan motor 3 will change according to the settings.
If the set rotation speed N set is significantly different from the rotation speed NDATA of the indoor fan motor 3 that is currently rotating, the detection time for the rotation speed of the indoor fan motor 3 is shortened, and conversely, the rotation speed of the indoor fan motor 3 is shortened. If there is a difference, the detection time is lengthened.

Subsequently, the rotation speed detection time Tc of the indoor fan motor 3 is T
Once f and Tn are determined, normal phase control is executed (
step 5T18), then return to step 5TIO,
The above steps are repeated. That is, l N5et
-NDATA While maintaining the relationship of I≧Sc, the conduction angle of the indoor fan motor 3 is changed by a certain amount dθ every rotation speed detection time Tf based on the detected rotation speed NDATA and the set rotation speed N set. Become. - The conduction that has been changed by a fixed amount dθ is the bidirectional thyristor 7.
Since the voltage is applied to the indoor fan motor 3 via the , the rotation speed of the indoor fan motor 3 can be changed. On the contrary, that l
As long as N set −N DATA≧Sc is not related,
For each detection time Tn, the rotation speed NDA of the indoor fan motor 3
TA is detected, and the conduction angle of the indoor fan motor 3 is changed by a fixed amount do every detection time Tn until the detected rotation speed NDATA reaches the set rotation speed N5et.

In this way, when the difference between the rotation speed NDATA of the currently rotating indoor fan motor 3 and the set rotation speed N5et becomes large, the time for changing the conduction angle of the indoor fan motor 3 by a certain amount is shortened. The rotation speed of the indoor fan motor 3 is quickly controlled to the set rotation speed. This results in
The indoor environment can reach the set value faster.

[Effects of the Invention] As explained above, according to the induction motor phase control method of the present invention, when the difference between the current rotation speed and the set rotation speed of the induction motor is large, the induction motor The rotation speed detection time is shortened, and if the difference is small, the rotation speed detection time is lengthened.
The rotational speed of the induction motor can be quickly set to the set rotational speed, and the rotational speed output characteristics (followability) of the induction motor can be improved. Therefore, if this phase control method is applied to the indoor fan motor of an air conditioner, the indoor environment can be made more comfortable faster.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and is a schematic block diagram of an air conditioner to which the method for controlling the rotation of a fan motor of an air conditioner is applied, and FIG. FIG. 3 is a diagram for explaining a table of conduction angle data, and a flow chart diagram for explaining the operation of a conventional induction motor. In the figure, 3 is an indoor fan motor, 4 is a motor drive unit, 5 is an indoor control device, 6 is an AC power supply, and 7 is a bidirectional thyristor. Patent Applicant: Fujitsu General Co., Ltd. Agent, Patent Attorney: Takuya Ohara

Claims (2)

[Claims] (1) When controlling the induction motor of the indoor fan motor to a set rotation speed, based on the rotation speed detected at predetermined intervals and the set rotation speed, the conduction angle of the induction motor is adjusted by a predetermined amount every time the rotation speed is detected. A phase control method for an induction motor in which the rotational speed of the induction motor is adjusted to the set rotational speed in stages by changing the rotational speed by dθ, A phase control method for an induction motor, characterized in that the rotation speed detection time interval is varied. (2) The phase control method for an induction motor according to claim (1), wherein the predetermined time is shortened when the difference between the current rotation speed of the induction motor and the set rotation speed becomes large.