JPH09152178A - Air conditioner and controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a torque characteristic of a blower, make a small-sized device and attain a high efficiency of the device by a method wherein a V-F characteristic between an output frequency and an output electrical power of an inverter can be set and varied in such a way that a maximum output voltage may be attained in response to a maximum output frequency corresponding to a designed maximum number of rotation of an outdoor blower to be connected. SOLUTION: Indoor air flowed to an indoor heat exchanger 6 is sent by an indoor blower 10, the surrounding air flowed to an outdoor heat exchanger 3 is sent by an outdoor blower 9. A power supply is supplied to this outdoor blower 9 through an inverter 11. If an output frequency from an inverter is high, an effective output voltage becomes high and in turn if the output frequency is low, the effective output voltage becomes low. In this case, under a V-F characteristic between an output frequency F and an output voltage V of the inverter, there is a relation in which V and F are proportional from each other in general. Then, the V-F characteristic is set in such a way that a maximum output voltage may be attained in reference to a maximum output frequency corresponding to a designed maximum number of rotation of the outdoor blower 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outdoor blower provided in an outdoor unit heat exchanger of an air conditioner and a control method thereof.

[0002]

2. Description of the Related Art As the technical flow of recent air conditioners,
A so-called multi-type in which a plurality of indoor units are connected to one outdoor unit has become widespread. In this multi-type air conditioner, the number of indoor units operated varies from time to time. Therefore, the outdoor unit needs to operate stably regardless of the operating capacity of the indoor unit. Therefore, as a necessary technique, a technique of controlling the refrigerant circulation amount by the rotation speed of the compressor and a technique of controlling the capacity of the outdoor unit heat exchanger by the rotation speed of the outdoor blower are indispensable.

In the latter technique, the outdoor blower provided in the outdoor heat exchanger is supplied with power via an inverter,
The output voltage to the outdoor blower is changed by changing the output frequency from the inverter. The motor of the blower is set based on the maximum output voltage (200V) and the power supply frequency (50 or 60Hz).

In the inverter, the output frequency is the maximum output frequency (50 or 60 Hz of the power supply frequency).
The VF characteristic (power source-frequency characteristic) is set so that the highest output voltage (for example, 200 V) is output at the time.
That is, for example, the VF characteristic as shown in FIG. 3 is set.

As an example, when a 4-pole motor is used to obtain the set maximum rotation speed (600 rpm) of the outdoor blower, the corresponding frequency is 25 Hz, and the output voltage obtained by this frequency is 100 V from the figure. Will end up. This 100V is much lower than the power supply voltage of 200V. Therefore, a large output current of 500 A is required to obtain a predetermined capacity (for example, 50 KW),
The capacity of the inverter becomes large. When using a 6-pole motor, the maximum design speed (600 rp
The frequency corresponding to m) is 30 Hz, the output voltage is 120 V from the figure, and the output current can be lower than the output current when the 4-pole motor is used. However, the 6-pole motor is likely to be larger than the 4-pole motor, and thus the entire blower is enlarged.

[0006]

A predetermined output frequency corresponds to the set maximum rotation speed (for example, 600 rpm) required for the outdoor blower. For example, the frequency is 30 Hz for an outdoor blower using a 6-pole motor, as described above. Therefore, 3
The operation is 0 Hz × 120 V. Further, the 4-pole motor has a frequency of 25 Hz, and the operation is performed at 25 Hz × 100V.

That is, even in the case of a 6-pole motor or a 4-pole motor, in the VF characteristic of FIG. 3, the operation is performed where the output voltage is always lower than the maximum output voltage (power supply voltage 200V). The lower the output voltage is, the larger the output current is, so that the capacity of the inverter is also increased. In addition, the efficiency of the torque characteristics of the blower may deteriorate.

The present invention has been made in order to solve the above-mentioned problems, and the capacity of the inverter can be reduced by operating at as large a voltage and a small current as possible to improve the efficiency in the torque characteristic of the blower, Therefore, it is an object of the present invention to provide an air conditioner that can be downsized and highly efficient.

[0009]

In order to achieve the above object, the invention of claim 1 is such that power is supplied to an outdoor blower provided in an outdoor unit heat exchanger via an inverter, and an output frequency from the inverter is output. In the air conditioner capable of changing the output voltage by changing the output voltage and thus changing the rotation speed of the outdoor blower, and connecting the VF characteristics of the output frequency (F) and the output voltage (V) of the inverter. The air conditioner is characterized in that the setting can be changed so that the maximum output voltage can be obtained by the maximum output frequency corresponding to the designed maximum rotation speed of the outdoor blower.

According to the second aspect of the present invention, the outdoor fan provided in the outdoor heat exchanger of the air conditioner is supplied with power through the inverter, and the output voltage from the inverter is changed to change the output voltage. A method for controlling an air conditioner capable of changing the rotation speed of an outdoor blower, comprising: VF of the output frequency (F) and the output voltage (V).
A method for controlling an air conditioner, characterized in that the characteristics are set such that the maximum output voltage is obtained at the maximum output frequency corresponding to the designed maximum rotation speed of the outdoor blower.

The invention according to claim 3 is further characterized in that the torque characteristic of the motor of the blower is set so as to have the maximum efficiency at the designed maximum rotation speed and the maximum output voltage. And a method for controlling an air conditioner according to claim 2.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to the drawings. FIG. 4 shows an overall circuit diagram of the air conditioner according to this embodiment. In the figure, three indoor units are connected to one outdoor unit. During the cooling operation, the refrigerant passes from the compressor 1 through the 4-way valve 2 and is sent to the outdoor heat exchanger 3 to exchange heat with the outside air. Then, it is sent to the indoor heat exchanger 6 through the receiver tank 4 and the expansion valve 5. The refrigerant vaporized here exchanges heat with the air in the room and exhibits a cooling function. Then, it is sent to the compressor 1 again through the 4-way valve 2 and the accumulator 7.

The indoor air to the indoor heat exchanger 6 is sent by the indoor blower 10. The outdoor air to the outdoor heat exchanger 3 is sent by the outdoor blower 9. Power is supplied to the outdoor blower 9 via an inverter 11.
During the cooling operation, the refrigerant moves in the opposite direction and circulates through the expansion valve 8 on the outdoor side.

Now, FIG. 5 shows the inverter 11 in detail, and shows changes in the supplied voltage (A to F in the figure).
That is, the voltage (A) supplied from the AC power supply 21 is stepped up (B) by the step-up transformer 22, and the converter unit 23
Is rectified at (C). It is smoothed in the inverter unit 24 (D) and output as a pulsed voltage (E, F). That is, if the output frequency from the inverter unit is high, the effective output voltage is high (E), and if the output frequency is low, the effective output voltage is low (F). In this way, the output voltage is changed by changing the output frequency, and thus the number of rotations of the outdoor blower can be changed and controlled. The change in the output frequency is obtained by the transistor drive signal output from the control circuit 25 to the inverter unit 24.

In the VF characteristic of the output frequency (F) and output voltage (V) of this inverter, V and F are generally in a proportional relationship. Then, in this embodiment, as shown in FIG. 1, the VF characteristic is set so that the maximum output voltage is obtained by the maximum output frequency corresponding to the designed maximum rotation speed of the outdoor blower 9.

The setting of the VF characteristic will be described in detail below. The outdoor blower 9 has a required capacity (for example, 5
If 0 KW) is set, assuming that the mechanical performance of the propeller and the like of the blower is the same, the maximum design rotation speed is set (for example, 600 rpm). The frequency corresponding to the designed maximum rotation speed is 23 Hz when the blower motor has four poles and 30 Hz when it has six poles (see the middle part of FIG. 6). Therefore, if a 4-pole motor is used, the VF characteristic of the inverter is set so that the maximum output voltage (200 V that is the power supply voltage) can be obtained with 25 Hz as the maximum output frequency (FIG. 1). .

By setting the VF characteristic in this way,
The following effects are obtained. That is, when the outdoor blower needs to operate at the designed maximum rotation speed (600 rpm), the maximum output frequency (25 H
z), which gives the highest output voltage (200V). The value of the power supply voltage is adopted as the maximum output voltage 200V. Therefore, a small current of 250 A is required to obtain the required capacity of 50 kW. This can minimize the capacity of the inverter.

On the other hand, the torque characteristic of the blower motor is set so that the maximum efficiency is achieved at the designed maximum rotation speed (600 rpm) and the maximum output voltage (200 V). As described above, the maximum output frequency (25 Hz) is output at the designed maximum rotation speed (600 rpm), and thus the maximum output voltage (200 V) is obtained. Therefore, the torque of the blower motor causes the maximum efficiency due to the torque characteristic. Is obtained.

A signal for driving a transistor forming the inverter section 24 is transmitted from the control circuit 25. In this control circuit 25, the VF characteristic can be changed according to the outdoor fan 9 to be connected. It can be changed as follows.

Thus, for example, as shown in FIG. 6, when the motor of the outdoor blower 9 to be connected has 6 poles instead of 4 poles (lower middle stage in FIG. 6), the maximum output frequency is 30 Hz.
In this case, the maximum output voltage (200V) is obtained. Therefore, the inverter 11 can be used in common depending on the outdoor blowers provided in the air conditioners having different refrigerating capacities.

When the required capacity of the connected outdoor blower 9 is 45 kW, the maximum design rotation speed is, for example, 5
The output frequency is 50 rpm, and the maximum output frequency is 23 Hz for the 4-pole motor blower and 28 Hz for the 6-pole motor blower. Therefore, this maximum output frequency 23
Maximum output voltage (200V) depending on Hz or 28Hz
The setting of the VF characteristic is changed so that

Further, the capacity required for the connected outdoor blower is 55 kW, and the set maximum rotation speed is 650 rpm.
Then, the blower using the 4-pole motor has a maximum output frequency of 27 Hz, and the blower using the 6-pole motor has a maximum output frequency of 32 Hz. Therefore, the maximum output voltage (2
The setting of the VF characteristic is changed so that 00V) is obtained.

As a result, the outdoor blowers provided in the air conditioners having different refrigerating capacities can be shared. Further, since the maximum efficiency is obtained in the torque characteristic of the blower motor, the number of motor poles of the blower can be changed from 6 poles to 4 poles, which enables downsizing of the motor, and thus downsizing of the entire blower.

In the above embodiment, the power supply voltage (step-up transformer 22) whose value is adopted as the maximum output voltage.
The supply voltage to the temporary side of was 200 V, but it can be 100 V in other embodiments.

[0025]

As described above, claim 1 or claim 2
According to the invention, the indoor blower is operated at the designed maximum rotation speed by setting the VF characteristic of the inverter so that the maximum output voltage is obtained by the maximum output frequency corresponding to the designed maximum rotation speed of the outdoor blower. Therefore, it is possible to operate at the maximum output voltage at all times, so that the output current becomes small and the capacity of the inverter can be made small accordingly.

Further, according to the first aspect of the invention, even if the indoor blower to be connected is changed and the design maximum rotation speed is changed, the maximum output voltage is obtained by the maximum output frequency corresponding to the changed design maximum rotation speed. Since it is possible to change the setting of the VF characteristic as described above, the capacity of the inverter can remain small and the inverter can be shared.

Further, according to the invention of claim 3, the torque characteristic of the blower is set so as to have the maximum efficiency at the designed maximum rotation speed and the maximum output voltage. At the same time, the maximum output frequency corresponding to the maximum rotation speed and the operation at the maximum output voltage are performed, so that the maximum efficiency is always obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing VF characteristics of an output frequency (F) and an output voltage (V) of an inverter according to an embodiment of the present invention.

FIG. 2 is a diagram showing a V-F characteristic in another embodiment.

FIG. 3 is a diagram showing VF characteristics in a conventional example.

FIG. 4 is a circuit diagram of the entire air conditioner in this embodiment.

5 is an explanatory diagram of the inverter of FIG.

FIG. 6 is a table showing values for explaining FIGS. 1 and 2;

[Explanation of symbols]

 1 Compressor 2 4-way valve 3 Outdoor heat exchanger 4 Receiver tank 5 Expansion valve (indoor side) 6 Indoor heat exchanger 7 Accumulator 8 Expansion valve (outdoor side) 9 Outdoor blower 10 Indoor blower 11 Inverter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuro Kishimoto 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. An outdoor fan provided in an outdoor unit heat exchanger is supplied with power via an inverter, and an output voltage is changed by changing an output frequency from the inverter,
Therefore, in the air conditioner capable of changing the rotation speed of the outdoor blower, the VF characteristic of the output frequency (F) and the output voltage (V) of the inverter corresponds to the designed maximum rotation speed of the outdoor blower to be connected. An air conditioner characterized in that the setting can be changed so that the maximum output voltage can be obtained at the maximum output frequency. 2. An outdoor blower provided in an outdoor heat exchanger of an air conditioner is supplied with power via an inverter, and an output voltage is changed by changing an output frequency from the inverter, so that a rotation speed of the outdoor blower. In a control method of an air conditioner capable of varying the maximum output voltage, the VF characteristic of the output frequency (F) and the output voltage (V) is determined by the maximum output frequency corresponding to the maximum design speed of the outdoor blower. A method for controlling an air conditioner, characterized in that the setting is made so that 3. The air conditioner according to claim 1, or the air conditioner according to claim 2, wherein the torque characteristic of the blower is set so as to have the highest efficiency at the designed maximum rotation speed and the maximum output voltage. Control method.