JPH0239180Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a variable capacity air conditioner, and particularly relates to control at the time of starting the compressor.

(b) Prior Art Compressors that use a variable speed electric motor to change capacity generally start by gradually increasing the rotational speed of the electric motor. Initially, both the compressor and the refrigeration cycle are cold, so liquid refrigerant flows into the suction port of the compressor and is discharged from the discharge port by the compressor. At this time, there was a problem in that the refrigerant dissolved in the lubricating oil accumulated in the chamber of the compressor turned into bubbles and evaporated, resulting in a forming phenomenon.

In order to solve these problems, Japanese Unexamined Patent Publication No. 1983
An attempt was made as described in Publication No. 152187. This is an air conditioner that consists of a compressor driven by a variable speed electric motor and a heat exchanger that absorbs and radiates heat by expanding and compressing refrigerant.
An air conditioner is described in which the compressor is operated at a certain rotational speed for a certain period of time, and then the compressor is controlled to further increase the rotational speed, thereby suppressing the forming phenomenon.

(c) Problems that the invention aims to solve In the air conditioners described above, the forming phenomenon was suppressed by operating at the above-mentioned certain rotation speed for a certain period of time, but in order to sufficiently suppress this forming phenomenon, It was necessary to take sufficient time for the above-mentioned period. This means that the time from the start of operation of the compressor to normal operation becomes longer, and especially at the start of heating operation, the heating effect is difficult to achieve.

In view of such problems, the present invention provides an air conditioner in which the startup time of the compressor is shortened.

(d) Means for solving the problem The present invention is a refrigeration cycle in which a compressor, a condenser, a pressure reducer, and an evaporator are sequentially connected in a ring with refrigerant piping. an inverter device that changes the number of rotations, a starting frequency control unit that gradually increases a rotation speed signal given to the inverter device at the start of operation of the electric motor, operates at a certain rotation speed for a certain period of time, and then further increases the rotation speed; and a voltage control section that makes the voltage applied to the electric motor higher than the voltage during normal operation when the electric motor is operating at a high rotational speed.

(E) Effect If the air conditioner is configured as described above, the voltage applied to the compressor motor will be higher than the optimum efficiency voltage, and the motor windings will generate heat, increasing the temperature inside the compressor. Therefore, the forming phenomenon can be suppressed, and the operating time at the certain rotation speed can be shortened, thereby shortening the startup time.

(F) Embodiment Below, the embodiment of the present invention will be explained based on the drawings. First, Fig. 1 is a schematic diagram of an air conditioner showing an embodiment of the present invention, and 1 is a compressor driven by a three-phase electric motor. machine, condenser 2, pressure reducing device 3, evaporator 4
are connected in a ring with refrigerant piping to form a refrigeration cycle. Reference numerals 5 to 10 indicate switching transistors, which are connected in a three-phase bridge configuration. A compressor 1 is connected to the output of this three-phase bridge. Reference numeral 11 denotes a signal generating section that outputs switching signals to the transistors 5 to 10, and together with the three-phase bridge, constitutes an inverter device. This signal generating section 11 outputs a switching signal at a frequency based on the rotational speed signal applied to the terminal F and by PWM (pulse width modulation). Incidentally, when a signal is applied to the terminal (V/F), the function of frequency and voltage finally applied to the motor of the compressor 1 is changed as shown in FIG. 2. That is, the characteristic shown by the solid line is the normal state, and by applying a signal to the terminal (V/F), the characteristic is switched to the characteristic shown by the dashed-dotted line.

12 is a microprocessor, and a setting device 13
The operation of the air conditioner is controlled based on the control data set in . Also, this microprocessor 1
2 includes a starting frequency control section that gradually increases a rotational speed signal given to the inverter device at the start of operation, operates at a certain rotational speed for a certain period of time, and then further increases the rotational speed; The motor includes a voltage control section configured with software and configured to make the voltage applied to the motor higher than the voltage during normal operation when the motor is in operation.

The main operations of this microprocessor 12 are based on the flowchart shown in FIG. First, values set by the setting device 13 and values of various temperatures and humidity are input as control data. Next, if the control data includes activation data, activation is performed based on the characteristics shown in FIG. This startup starts with “F=
A rotational speed signal of f ₀ ” is output to the signal generator 11.
After this, the rotation speed is gradually increased by “F=F+α” (α is an arbitrary value and can be set arbitrarily according to the specifications of the air conditioner) until the rotation speed signal reaches “F=f ₁ ”. let When the rotation speed signal reaches “F=f ₁ ”, a signal is output to the terminal (V/F) of the signal generator 11 and a predetermined time (approximately 30 seconds) is required until the time increases.
Maintain this state. That is, the frequency is “f ₁ ”Hz
A three-phase alternating current with a voltage higher than that during normal operation is applied to the motor of the compressor 1 for a predetermined period of time. Thereafter, the rotational speed signal is further increased by "α", and when the rotational speed signal reaches "F=f ₂ ", the startup is completed and normal operation is performed.

When starting the operation of the air conditioner configured as described above, the rotation speed of the compressor 1 is increased to "F=f ₂ " based on the characteristics shown in FIG. 4, and then normal operation is started. At this time, when the compressor 1 is operating at a certain rotation speed for a certain period of time, the voltage applied to the motor of the compressor 1 is made higher than the voltage during normal operation. By increasing the internal temperature of the compressor 1, the forming phenomenon can be quickly suppressed, and the above-mentioned fixed time can be shortened, thereby shortening the start-up time.

FIG. 5 is a characteristic diagram showing another embodiment, which replaces the characteristic diagram of FIG. 2 used in the above embodiment. As a result, while the rotational speed (frequency F) of the compressor 1 is "f ₀ ≦F≦f ₁ ", a voltage higher than the voltage during normal operation is applied to the motor windings. Since the time during which this higher voltage is applied is longer than in the above embodiment, the amount of heat generated from the winding increases, and the startup time can be further shortened.

(g) Effects of the invention The air conditioner of the invention has a refrigeration cycle configured by sequentially connecting a compressor, a condenser, a depressurizer, and an evaporator in a ring with refrigerant piping. an inverter device that changes the rotation speed of the motor, a starting frequency control unit that gradually increases the rotation speed signal given to the inverter device when the motor starts operating, operates at a certain rotation speed for a certain period of time, and then increases the rotation speed further; and a voltage control unit that makes the voltage applied to the motor higher than the voltage during normal operation when the motor is operating at a certain rotation speed,
While a voltage higher than the voltage during normal operation is applied to the motor, the amount of heat generated by the windings of the motor increases, causing the temperature inside the compressor to rise quickly. That is, it is possible to suppress the forming phenomenon at the time of starting the compressor and to shorten the starting time.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an air conditioner showing an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the relationship between frequency and voltage applied to the compressor of Fig. 1, and Fig. 3 is a diagram similar to the one shown in Fig. 1. FIG. 4 is a flowchart showing the main operations of the microprocessor shown in FIG. 4, a characteristic diagram showing the relationship between time and frequency at startup when using the embodiment of the present invention, and FIG. FIG. 7 is a characteristic diagram showing the relationship between frequency and voltage in another embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Compressor, 2... Condenser, 3... Pressure reduction device, 4... Evaporator, 11... Signal generation part, 12...
...Microprocessor, 13...Setting device.

Claims (1)

[Scope of utility model registration request] In a refrigeration cycle configured by sequentially connecting a compressor, condenser, pressure reducing device, and evaporator in a ring with refrigerant piping, there is an inverter device that changes the rotation speed of the electric motor for the compressor, and an inverter device that changes the rotation speed of the electric motor for the compressor, and an inverter device that changes the rotation speed of the electric motor when the electric motor starts operating. a starting frequency control section that gradually increases a rotational speed signal given to the motor, operates at a certain rotational speed for a certain period of time, and then further increases the rotational speed; An air conditioner characterized by comprising a voltage control section that raises the voltage higher than that during normal operation.