JP2652019B2 - Refrigeration cycle frequency controller - Google Patents

Description

The present invention relates to a refrigeration cycle frequency control device,
In particular, the present invention relates to a frequency control device capable of controlling the number of revolutions of a motor in consideration of a primary current of the motor and a fan speed of an indoor heat exchanger.

[Conventional technology]

FIG. 2 shows a conventional speed control device of a motor of an air conditioner disclosed in Japanese Patent Publication No. 28902/1986. In the figure, 1 is an operation input device for instructing the operation mode of the air conditioner, 2 is an indoor target temperature setting device, 3 is a room temperature sensor, 4 is a logical operation device, a temperature deviation detector 5, an initial speed generator. 6, an operation / stop signal generator 7, a temperature deviation change detector 8, a temperature deviation upper limit detector 9, an operation speed holder 10, and a timer 11. 12 is a motor operation controller, 13
Denotes a motor, which indicates a compressor motor.

 Next, the operation will be described.

The logical operation device 4 includes operation modes such as cooling and heating from the operation input device 1 and an operation / stop command of the air conditioner,
Target room temperature information from the setter 2 and an output obtained by converting an analog output signal from the room temperature sensor 3 into a digital signal are input. The logical operation device 4 performs a logical operation on the basis of these inputs, and outputs a start / stop signal and a speed signal of the electric motor 13 to the electric motor operation controller 12 so that the operation controller 12 controls the electric motor 13. Control the operation.

[Problems to be solved by the invention]

In the conventional motor speed control method as described above, the target room temperature by the setter 2 and the output from the room temperature sensor 3 are input to the logical operation device 4 and the frequency is controlled only by the room temperature. When the frequency is increased by the deviation signal from the target temperature, the current is caught on the upper limit current, the overcurrent prevention means of the refrigeration cycle operates, and the air conditioner may become inoperable. For this reason, the upper limit of the maximum frequency must be set according to the temperature level, and in addition to this, a primary current protection measure at the time of overload such as liquid back is required.

Furthermore, in the heating operation mode, when the temperature of the indoor fan (not shown) of the indoor heat exchanger blown into the room at the start of the operation is low, the user may feel uncomfortable due to the draft, and thus reduce the indoor fan speed. In addition, during the heating operation, the user may arbitrarily lower the indoor fan speed by operating a remote controller or the like. When the indoor fan speed decreases, the heat transfer rate decreases as the air flow rate of the indoor fan, which is the condenser, decreases due to the decrease in speed, and the condenser temperature, and thus the high pressure, increases, and the load on the compressor increases rapidly. However, there is a problem that the upper limit of the primary current is suddenly exceeded.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in a heating operation mode, can obtain a frequency control device for a refrigeration cycle that can control the frequency of an electric motor before an overcurrent cutoff and has a fast start-up speed. The purpose is to:

[Means for Solving the Problems] The frequency control device for a refrigeration cycle according to the present invention measures the primary current of the operating compressor motor, and at each sampling time of a predetermined cycle, the past of the primary current is measured. A current value predicting means for calculating and outputting a predicted value of a primary current at the next sampling time from an increment within one sampling period, an indoor fan speed detecting means for detecting a fan speed of the indoor heat exchanger, and a heating operation mode. When the fan speed detected by the indoor fan speed detecting means changes from a high air flow to a medium air flow, and when the air flow changes from a medium air flow to a small air flow, the influence of the indoor fan speed change on the primary current is calculated by the primary current The predicted current value is added to the predicted value of the current value, and it is determined whether the added predicted current value is within a preset current value width. Control means for increasing the frequency corresponding to the speed command when it is full, and reducing the frequency corresponding to the speed command when the predicted current value exceeds the current value width.

[Action]

In the frequency control device of the refrigeration cycle of the present invention, when the indoor fan speed decreases in the heating operation mode,
The influence on the primary current is added to the predicted value of the primary current value, and when the added predicted current value is less than a preset current value width, the frequency for the speed command is increased and corrected, thereby increasing the start-up speed of the refrigeration cycle. It becomes possible to advance, and when the predicted current value exceeds a preset current value width, by decreasing and correcting the frequency with respect to the speed command, without overcurrent interruption below the upper limit current,
Fast rotation can be continued.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes the operation / stop and cooling of the air conditioner,
An operation input device for designating an operation mode such as heating, a target temperature design device for setting a target temperature in a room to be air-conditioned, a room temperature sensor, a logical operation device, and a difference between a set target temperature and a room temperature. , An initial speed generator 6 for the electric motor 13, a start / stop signal generator 7 for the electric motor 13, and an operation speed holder 10 for the electric motor 13. The signal is input to an initial speed generator 6 and a start / stop signal generator 7. The output signal of the temperature deviation detector 5 is input to an operation / stop signal generator 7 and an operation speed holder 10. The output signal of the initial speed generator 6 is input to the operating speed holder 10. Further, the outputs of the operation / stop signal generator 7 and the operation speed holder 10 are connected to the motor operation controller 12.
To be entered.

Further, the logical operation device 4 includes a current differentiator 15 that obtains a change amount of a primary current value from a current sensor 14 that detects a primary current of the electric motor 13 and outputs a predicted current value, and an operation of the current differentiator 15. When the timer of the indoor heat exchanger changes from a high speed to a medium speed and a medium speed to a low speed, for example, when the room temperature is low at the start of the heating operation mode, the fan of the indoor heat exchanger is At high speeds it is necessary to change to a lower speed immediately to feel a draft,
At this time, the speed is switched in a one-step deceleration direction from a high speed to a medium speed or from a medium speed to a low speed based on a speed signal from a fan speed detector 18 for detecting a fan speed of the indoor side heat exchanger. As a result, both the high pressure and the low pressure of the electric motor 13 increase. Therefore, the primary current of the electric motor 13 increases, and the amount of current change as an effect on the primary current of the electric motor 13 is approximated as ΔI ₂ . The magnitude of ΔI ₂ is determined as a change in current as the primary current increases due to an increase in the high pressure and the low pressure of the electric motor 13. This ΔI ₂ and the current differentiator
Determining whether the preset current value width the sum of the predicted current value I + △ I ₁ from 15, a current width determiner 17 for outputting an output signal of the result to the operating speed retainer 10 ing. The current differentiator 15 is a circuit that receives an output of the current sensor 14, predicts a current value one sampling point after the current time point, and outputs the predicted current value. A detailed configuration example will be described. The output I of the current sensor 14 is sampled at each sampling time point, and a difference ΔI ₁ between the value of I and the value stored in the first register (not shown) with the value of I one sampling point before. And I + Ｉ
Second register to the value of I ₁ and the predicted current value stored in the (not shown) current contents of the second register width determiner 17 outputs to the said first time by the value of I of current sampling time Means for updating the contents of the register. The pulse indicating the sampling time is supplied from the timer 16.

An operation in the heating operation mode of the present embodiment configured as described above will be described.

The logical operation device 4 includes a heating operation mode and an operation / stop command of the air conditioner from the operation input device 1, target room temperature data from the setting device 2, an output signal from the room temperature sensor 3, and a primary current sensor 14. Each output of the fan speed detector 18 is input. The logical operation device 4 performs a logical operation based on these inputs, and outputs a start / stop signal and a speed signal of the electric motor 13 to the electric motor operation controller 12. The operation controller 12 controls the operation of the electric motor 13 according to this signal.

 Next, the operation of the logical operation device 4 will be described in detail.

The temperature deviation detector 5 compares the set value of the setting device 2 with the room temperature measured by the room temperature sensor 3, converts the value into a temperature deviation ΔT, and converts the value into an operation / stop signal generator 7 and an operation speed holder. Output to 10.

The run / stop signal generator 7 receives a signal from the operation input device 1 and an output signal from the temperature deviation detector 5 and outputs a run or stop signal to the motor operation controller 12. At the start of the operation, the signal from the operation input device 1 is received by the initial speed generator 6, and the initial speed is sent to the operation speed holder 10. Further primary current sensor
The signal 14 is input to the current differentiator 15 to obtain the difference ΔI ₁ from the primary current value of the timer 16 a predetermined time Δt before. In addition, as described above, the fan speed of the indoor heat exchanger is generally reduced by one step between three stages of high speed (ie, high air volume), medium speed (ie, medium air volume), and low speed (ie, small air volume). Direction. When the direction is switched to the one-step deceleration direction, the influence on the primary current of the compressor motor is output by approximating ΔI _2, and otherwise “0” is output.

Therefore, the sum of the primary current I measured by the current differentiator 15 and the difference ΔI ₁ and ΔI ₂ from the fan speed detector 18 is input to the current width determiner 17 as an output. Thus, the current change ΔI ₂ when the speed of the indoor fan decreases is added to the predicted current value I + ΔI ₁ of the primary current. When the value of the predicted current I + △ I ₁ + △ I ₂ is smaller than the preset low value I ₁ of the current width, the current width determiner 17 sets “+1”, and the predicted primary current I + △ I ₁ + △ I _{When 2} is greater than the high value of the current width I _2,
1], and the value of the predicted current I + ΔI ₁ + ΔI ₂ is the current width.
When it is within I ₁ -I ₂ , a value of “0” is output to the operating speed holder 10.

The operating speed holder 10 receives signals from the initial speed generator 6, the temperature deviation detector 5, and the current width determiner 17. When the signal from the initial speed generator 6 is logic “1”, a preset initial speed is issued to the operation controller 12 with priority. When there is no signal from the initial speed generator 6 (in the case of logic "0") and the signal from the current width determiner 17 is "0", the temperature deviation ΔT from the temperature deviation detector 5 is present. K multiplied by set value K
The speed change amount of ΔT _Hz is output to the motor operation controller 12.
When the signal of the current width determiner 17 is “+1”, the speed change amount K △ T _Hz and the increase correction amount △ Hz are added, and K △ T _Hz +
ΔHz, and conversely, when the signal of the current width determiner 17 is “−1”,
K △ T _Hz − △ Hz, which is the speed change amount K △ T _Hz plus the decrease correction amount
Is output to the operation controller 12.

As described above, in the heating operation mode, the sum of the predicted current after a predetermined time from the value of the primary current sensor 14 and the change in the primary current of the compressor motor based on the output signal from the indoor fan speed detector 18 is determined in advance. When it is predicted to be less than the set current value width, the frequency increase correction is executed, and when it is predicted to exceed the preset current value width, the frequency decrease correction is executed. Accordingly, the frequency of the electric motor can be controlled, so that the operation can be continued even during the overload operation such as the liquid back without interrupting the overcurrent, and the rising speed of the refrigeration cycle can be reduced. When the speed of the indoor fan decreases, both the high pressure and the low pressure increase. Therefore, the primary current of the compression motor increases, and the increased current change is added to the predicted current value of the primary current. As a result, the primary current value is corrected within the current value range, so that the primary current can be quickly and more accurately controlled within the allowable current range, and the conventional overcurrent prevention measures and protection of the primary current during overload can be achieved. No measures are required.

Although the primary current sensor 14 is provided in the above embodiment,
Instead, a torque sensor of the electric motor 13 may be used.

〔The invention's effect〕

Since the present invention is configured as described above, when the indoor fan speed decreases in the heating operation mode,
When the predicted current value is less than the set current width, the frequency is further increased and corrected, and when the predicted current value exceeds the set current width, the frequency is decelerated and corrected, so that the upper limit current value is not caught. The operation can be continued even in the event of an overload, and there is an effect that the starting speed can be shortened, and the comfort can be improved at the same time as the reliability of the crisis.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a control device to which the control method of the present invention is applied, and FIG. 2 is a block diagram of a conventional control device. 1 ... operation input device, 2 ... target temperature setting device, 3 ... room temperature sensor, 4 ... logical operation device, 5 ... temperature deviation detector,
6 ... initial speed generator, 7 ... run / stop signal generator,
8: Temperature deviation change setting device, 9: Temperature deviation upper limit generator, 10: Operating speed holder, 12: Motor operation controller,
13 ... electric motor, 14 ... primary current sensor, 15 ... current differentiator, 16 ... timer, 17 ... current width determiner, 18 ... indoor fan speed detector. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] A temperature control means for controlling a speed of the compressor to be controlled by frequency control, wherein a temperature deviation detecting means detects a target room temperature to be air-conditioned as a temperature deviation from an actual room temperature, and increases or decreases the speed according to the temperature deviation. In a frequency control device of a refrigeration cycle that generates a command to control the speed of the compressor motor, a primary current of the compressor motor during operation is measured, and the primary current of the primary current is measured at every sampling time of a predetermined cycle. Current value predicting means for calculating and outputting a predicted value of the primary current at the next sampling time point from an increment within one past sampling period; indoor fan speed detecting means for detecting a fan speed of the indoor heat exchanger; In the operation mode, when the fan speed by the indoor fan speed detecting means changes from the high air volume to the medium air volume and from the medium air volume to the small air volume, In addition, the influence of the change in the indoor fan speed on the primary current of the compressor motor is added to the predicted value of the primary current value by the current value prediction means, and the added predicted current value falls within a preset current value width. When the predicted current value is less than the current value width, the frequency for the speed command is increased and corrected, and when the predicted current value exceeds the current value width, the frequency for the speed command is reduced and corrected. Control means for controlling the frequency of the refrigerating cycle.