JPH0228353Y2 - - 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 start of heating operation.

(b) Prior art In general, an air conditioner equipped with a compressor whose capacity can be changed using a variable speed electric motor is disclosed in Japanese Patent Application Laid-Open No. 53-46150.
There was something like the one described in the issue. This publication describes a system in which the voltage and frequency of an inverter power source are varied depending on the load condition to operate the compressor at variable speed. In such air conditioners, the voltage that maximizes the operating efficiency of the compressor is set according to the rotation speed (frequency) of the compressor, and the compressor is operated at a rotation speed that matches the load condition. I was getting used to it.

Therefore, at the start of heating operation, the compressor is driven at a rotation speed determined based on the set temperature and room temperature.

(c) Problems that the invention aims to solve In the conventional air conditioners described above, the rise time (the time it takes for the room temperature to reach the set temperature) at the start of heating operation is determined by the maximum capacity of the compressor. There is a limit to how much the rise time can be shortened in consideration of this maximum capacity.

In view of these problems, the present invention provides an air conditioner in which the rise time is further shortened.

(d) Means for solving the problem The air conditioner of the present invention has a compressor, a condenser, a pressure reducing device, and an evaporator each having an electric motor whose rotational speed can be changed by an inverter device, which are connected in order in a ring shape through refrigerant piping. This refrigeration cycle is equipped with an inverter device that increases the voltage/frequency ratio applied to the motor at the start of heating operation compared to during normal operation.

(E) Effect If the air conditioner is configured in this way, the voltage applied to the compressor motor will be higher than the optimum efficiency voltage at the start of heating operation, and the windings of the motor will generate heat, causing the refrigerant inside the compressor to increase. heat up. Therefore, the amount of heat dissipated by the condenser increases, and the start-up time during heating operation can be shortened.

(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 a rotational speed signal applied to a terminal F and by PWM (pulse width modulation). Incidentally, when a signal is applied to the terminal (V/F), the relationship between the frequency and voltage finally applied to the motor of the compressor 1 is changed as shown in FIG. 2. In other words, the characteristic shown by the solid line is the normal state, and the terminal (V/F)
By applying a signal to , the characteristics are switched to the one shown by the dashed line. For example, during normal operation, when the frequency is ₁ , a voltage of υ [V] is applied to the motor of the compressor 1, and when a signal is applied to the terminal (V/F) of the signal generator 11, the frequency is ₁ . υ′ [V]
voltage is applied to the motor of the compressor 1.

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 unit that gradually increases a rotational speed signal given to the inverter device at the start of operation;
The software provides a function that outputs a signal to the terminal (V/F) of the signal generator 11 to make the voltage applied to the motor higher than the voltage during normal operation until the temperature in the conditioned room reaches a certain value. It is configured and built-in.

The main operations of this microprocessor 12 are based on the flowchart shown in FIG. First, data such as the room temperature set value (T ₀ ) of the conditioned room, various set values such as humidity, and the temperature (T) of the conditioned room by the setting device 13 are input as control data. Next, if there is starting data in this control data, the following starting process is performed, and if there is no starting data, normal heating operation is performed in which the motor of the compressor 1 is driven at a frequency matched to the load condition.

If there is activation data, the microprocessor 12 first outputs a signal to the terminal (V/F) of the signal generator 11 and maintains this signal output. Next, the frequency signal is increased from ₀ to ₂ by a predetermined width (α). (α is an arbitrary value and can be set arbitrarily according to the specifications of the air conditioner.) When the frequency signal becomes ₂ , the temperature (T) in the conditioned room becomes “T≧T ₀ ”.
(T ₀ is the room temperature set value), maintain the output of this frequency signal ( ₂ ).

After that, when "T≧T ₀ ", the signal output to the terminal (V/F) of the signal generator 11 is stopped, and then the same normal operation as above is performed.

When you start operating such an air conditioner, the compressor 1 is turned on from the start of startup to the end of startup (when F = ₂ ) to the end of heating start-up (when T≧T ₀ ). The voltage applied to the motor has the characteristics shown by the dashed line in Figure 2. After T≧T ₀ is reached, the characteristics shown by the solid line in FIG. 2 are obtained. While using the characteristics shown by the dashed line in FIG. 2, the voltage applied to the motor of the compressor 1 is higher than the highest efficiency voltage with respect to frequency. This high voltage causes heat loss in the motor windings, increasing the temperature inside the compressor. That is, the refrigerant can be heated inside the compressor 1, the amount of heat released by the condenser 2 can be increased, and the rise time during heating operation can be shortened.

(g) Effects of the invention The air conditioner of the invention constitutes a refrigeration cycle by sequentially connecting a compressor, a condenser, a pressure reducing device, and an evaporator with an electric motor whose rotation speed is changed by an inverter device in a ring shape through refrigerant piping. The device is equipped with an inverter device that increases the voltage/frequency value applied to the motor at the start of heating operation than during normal operation without changing the frequency, so a higher voltage than usual is applied to the motor at the start of heating operation. This higher voltage causes heat loss in the motor windings, and the temperature inside the compressor rises. In other words, while ensuring stable operation of the compressor, the refrigerant can be heated inside the compressor without installing any other heating means, increasing the amount of heat dissipated from the condenser and shortening the start-up time during heating operation compared to conventional methods. be able to.

[Brief explanation of the drawing]

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. 3 is a flowchart showing the main operations of the microprocessor shown in FIG. 1... Compressor, 2... Condenser, 3... Pressure reducing device, 4...
Evaporator, 11... Signal generator, 12... Microprocessor, 13... Setting device.

Claims (1)

[Scope of utility model registration request] A refrigeration cycle is configured to be capable of heating operation using a compressor, a condenser, a pressure reducer, and an evaporator driven by an electric motor, and the electric motor receives AC power controlled so that the voltage/frequency value is a predetermined value. 1. An air conditioner comprising an inverter device that supplies power to the air conditioner, the air conditioner comprising a mechanism for increasing the predetermined value without changing the frequency at the start of heating operation.