JPH0979669A - Air conditioning equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide air conditioning equipment enabling easy attainment of a sufficient quantity of heat and execution of heating suitable to environmental conditions. SOLUTION: This equipment has a control means 3 which makes phases U and V of a three-phase AC motor 1 be at potentials being equal substantially to N of a DC power source 4 by turning transistors 16U and 16V ON and transistors 6U and 6V OFF and controls a phase W to be at a necessary potential by subjecting ON-OFF operations of transistors 6W and 16W to a pulse width control, at the time of stoppage of a compressor 2. Thereby the motor 1 can be heated uniformly without being overheated or heated insufficiently and a proper quantity of heating can be maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for preheating a compressor by using means capable of freely changing the rotation speed of the compressor.

[0002]

2. Description of the Related Art Generally, in an air conditioner, when the ambient temperature of the compressor is low, the refrigerant inside the compressor may be dissolved in the lubricating oil. When the operation is started under such a condition, a forming phenomenon occurs in which the refrigerant dissolved in the lubricating oil in the compressor tries to vaporize,
Lubricating oil is carried outside the compressor, which causes a decrease in the reliability of the compressor, and the problem that the circulation amount of the refrigerant does not increase and the startup of the device is delayed occurs.

Therefore, in the past, a heater for preheating was separately provided in the vicinity of the compressor, and when the temperature was low, the heater was energized to heat the compressor so that the temperature inside the compressor did not fall below a certain level. I was adjusting. In recent years, compressors driven by inverters have become widespread, and those that use inverters as heating means have been proposed.
For example, as a method described in JP-A-61-6549, there is a method in which a compressor is heated by applying a non-rotatable high frequency, and JP-A-61-14487.
As a method described in (3), there is a method of heating by energizing only two of the three phases so that the compressor does not rotate.

[0004]

However, in the method described in the above-mentioned Japanese Patent Laid-Open No. 61-6549, 25
It is necessary to generate a signal that is driven in an inaudible range such as kHz, and furthermore, the electric current is determined by the electric constant of the motor at that time, and when trying to change the current, it is necessary to take very complicated means. There is a problem that exists. Further, in the method described in Japanese Patent Laid-Open No. 61-14487, since only two phases are energized, current flows only between one phase (two resistances as a Y connection). The amount becomes small, and it is necessary to secure the current amount in order to secure the heat generation amount, which causes a problem that the load on the inverter element becomes large.

Further, in the conventional methods, since the constant energization is carried out regardless of the environmental conditions in any case, there is a problem that preheating becomes insufficient especially in a low temperature state and overheating occurs when the temperature is not so low. .

In consideration of such problems in the conventional compressor heating, the present invention provides an air conditioner which can easily obtain a sufficient heat generation amount and can perform heating suitable for environmental conditions. It is intended.

[0007]

According to the present invention, there is provided a power conversion means for converting a DC voltage into a three-phase AC voltage, and a compression means for a refrigerant driven by the three-phase AC voltage converted by the power conversion means. Of the three-phase output terminals of the power conversion means when the compression means is stopped, two phases have the same first potential, and the remaining one phase has a second potential different from the other two phases. It is an air conditioner provided with the control means which controls a conversion means.

For example, of the three output terminals of the inverter circuit as the power conversion means, the potentials of two terminals are made substantially equal to the negative side of the DC voltage, and the potentials of the remaining terminals are pulse width according to the compressor temperature. By controlling and adjusting, current flows through all the windings of the motor, and optimum heating of the compressor can be performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing an embodiment. (First Embodiment) FIG. 1 is a block diagram showing a configuration of an air conditioner according to a first embodiment of the present invention. In FIG. 1, between the positive output (P) and the negative output (N) of the DC power supply unit 4, the U phase and V of the three-phase induction motor 1 are connected.
Six transistors 6U to correspond to the phase and W phase,
A three-phase bridge circuit composed of 16U, 6V, 16V, 6W, 16W is connected. Freewheeling diodes 7U and 17 are provided between the collector and emitter of each transistor.
U, 7V, 17V, 7W, and 17W are provided to form a current path when the transistor is off. Control information for each transistor is sent from the control means 3 via the interface circuits 5U, 15U, 5V, 15V, 5W, 15W.

The output terminal of the three-phase bridge circuit is connected to the three-phase AC motor 1, and the compressor 2 has
A compressor temperature detecting means 13 for detecting the temperature is provided, and its output is connected to the control means 3. Also, a three-phase bridge circuit and an interface circuit 5U,
15U, 5V, 15V, 5W, 15W and the like constitute power source conversion means, and the three-phase AC motor 1 and compressor 2 constitute compression means.

Next, the operation of the air conditioner of the first embodiment will be described with reference to the drawings.

First, the control means 3 controls the pulse width modulation of each transistor so that the output of the three-phase bridge circuit becomes a three-phase AC when the air conditioner is operating. The three-phase AC rotates the three-phase AC motor 1 and operates the compressor 2.
A refrigerant is compressed by the operation of the compressor 2, and a refrigeration cycle in which the refrigerant is returned to the compressor 2 via the condenser 8, the expansion mechanism 9, and the evaporator 10 is configured, and a function as an air conditioner is realized. . The control means 3 also controls the cooling fan 11 for the condenser 8, the cooling fan 12 for the evaporator 10, and the like. The details are publicly known and will be omitted.

On the other hand, when the operation is stopped and the outside air temperature is low, the three-phase AC motor 1 is controlled so that a minute current flows. FIG. 2 shows an example of the control signal waveform. In FIG. 2, the top three waveforms show the electric potential of the motor terminal, and the bottom three waveforms show the voltage between the lines.

First, the electric potential of the motor terminal will be described. U
The phase potential is almost equal to N of the DC power supply 4. That is, the transistor 16U in FIG. 1 is turned on and the transistor 6U is turned off. Similarly for the V phase, the transistor 16V turns on and the transistor 6V turns off.
It has been done. That is, the U-phase and V-phase potentials are equal,
This potential is the first potential. Next, in the W phase, there is a period in which the potential is equal to P of the DC power supply 4 and a period in which it is equal to N, and the average potential as the second potential is between them.
That is, the transistor 6W is turned on and the transistor 16W is turned off in the period t1, and the transistor 16W is turned on and the transistor 6W is turned off in the period t2.

Next, the interphase voltage between the motor terminals will be described. In the inter-phase voltage, the voltage between PN is denoted by v. The voltage between UV is zero because the two phases have the same potential. The voltage between V and W is -v in the t1 period.
, And is zero during the t2 period, and the average value is a value in between. Similarly, the voltage between W and U is + v during the t1 period and zero during the t2 period. After all, the potentials of U and V with respect to W are between -v and zero, and their values are equal. As a result, during U-W, V-W
Since a voltage is generated during the period, current flows through the three-phase AC motor 1, but no current flows between U and V. Moreover, the current flows from W to U and V, the magnitudes of which are the same, and the rotating magnetic field is not generated. Therefore, all of these electric currents are consumed as heat. Further, if the period t1 is lengthened, the average value of the interphase voltage increases and the current increases, and if the period t2 is lengthened, the average value of the correlation voltage decreases and the current decreases.

FIG. 3 is a block diagram showing the internal structure of the control means 3 in the first embodiment. The control means 3 comprises a comparison means 24, a compensation calculation means 23, a three-phase distribution means 22, and a pulse width modulation means (PMW) 21, and is obtained by the compressor temperature detection means 13 provided in the compressor 2. The obtained temperature information is input to the comparison means 24, and the comparison means 24 compares it with a preset target temperature. The comparison result is sent to the compensation calculation means 23, and a control calculation for ensuring the temperature control performance, for example, a PID control calculation is performed. The result of the calculation is sent to the three-phase distribution means 22, where it is determined what potential is to be applied to the three phases U, V and W. The distribution result is sent to the pulse width modulation means 21, is pulse width modulated, and is three-phase bridge circuit 2.
Sent to 0 to get the motor applied voltage.

The three-phase bridge circuit 20 includes transistors 6U, 16U, 6V, 16V, 6W, 16W, shown in FIG.
Freewheeling diodes 7U, 17U, 7V, 17V, 7W, 1
7W and interface circuits 5U, 15U, 5V,
It is composed of 15V, 5W, and 15W. The operation in FIG. 3 will be described. If the detected compressor temperature is lower than the target temperature, the current amount is increased so that the temperature rises, and if it is higher than the target temperature, the current amount is decreased. As a result, the three-phase AC motor 1 can be preheated without excess or deficiency. It should be noted that the compressor temperature detecting means 13 can be the one used for normal air conditioning control. As another simple method, it is also possible to use the information of the means for measuring the temperature of the discharged refrigerant, which is attached near the discharge port of the compressor.

FIG. 4 is a block diagram showing the configuration of the air conditioner of the second embodiment according to the present invention. The basic configuration of the air conditioner of the present embodiment is the same as that of the first embodiment of FIG. 1, and the different point is the control means 3
The temperature information input to is, instead of the temperature of the compressor 2,
This is a point that the temperature around the compressor 2 is used. Therefore, instead of the compressor temperature detecting means 13, the outside air temperature detecting means 14 is provided around the compressor 2 (here, near the evaporator 10). That is the point.

FIG. 5 is a block diagram showing the internal structure of the control means 3 in the second embodiment. The control means 3 is composed of an information conversion means 25, a three-phase distribution means 22, and a pulse width modulation means 21, and the temperature information obtained by the outside air temperature detection means 14 is input to the information conversion means 25, and the information is obtained. The conversion means 25 converts the output value into a preset output value. As shown in FIG. 5, the conversion method is such that the output value decreases when the outside air temperature is high, and the output value increases when the outside air temperature is low. The conversion result is the three-phase distribution means 22.
Then, it is determined what kind of potential is applied to the three phases U, V and W. The distribution result is the pulse width modulation means 21.
To the three-phase bridge circuit 20 to obtain the motor applied voltage.

The operation of FIG. 5 will be described. The lower the outside air temperature is, the more the current amount is increased, and the higher the outside air temperature is, the more the current amount is decreased. If the outside air temperature is high, the current amount required for heating is small, and if it is low, a large current amount is required. With the above, the three-phase AC motor 1 can be preheated with almost no excess or deficiency. As the outside air temperature detecting means 14, the one used for normal air conditioning control may be used as it is.

As described above, according to the air conditioner of the present invention, it is possible to apply a current to all the phases of the three-phase AC motor to uniformly heat the motor, while having a simple structure. By controlling the current based on the temperature of the compressor or its surroundings, the motor is neither overheated nor underheated. Furthermore, the current flowing in all phases and the transistors other than one phase do not include the transient state, the heat generation of the driving transistors is dispersed and the heat generation is suppressed, so the reliability is also improved. To do.

In each of the above embodiments, the two-phase potential is fixed to one potential of the DC power source and the remaining one-phase potential is controlled. However, instead of this, the one-phase side is controlled. The electric potential of 2 may be fixed and the electric potentials on the two-phase side may be simultaneously controlled so as to be the same electric potential. In this case, the amount of current depending on the temperature may be adjusted by controlling the potentials on the two-phase side.

In each of the above embodiments, the potential of the two phases is fixed to one of the potentials of the DC power source. However, instead of this, the potential of the two phase side is the same potential different from the potential of the one phase side. You may control simultaneously so that it may become. In this case, the adjustment of the amount of current depending on the temperature may be performed by controlling the potential on the one-phase side, the potential on the two-phase side, or both so as to satisfy the condition of the three-phase potential in the present invention. Good.

In each of the above embodiments, the two phases are fixed to the negative side of the DC power source, but instead of this,
Of course, it may be fixed to the plus side. In this case, ON / OFF of the transistor may be controlled in reverse.

Further, in the above embodiment, the two phases having the same potential are fixed to the U and V phases, but instead of this,
At the speed that the motor does not rotate the two phases that have the same potential,
For example, the configuration may be such that the V, W phase, W, U phase, U, V phase are sequentially switched.

In each of the above embodiments, the control means is constituted by dedicated hardware, but instead of this, the same function may be realized by software using a computer.

[0027]

As is apparent from the above description, according to the present invention, when the compression means is stopped, two phases among the three-phase output terminals in the power conversion means are set to the same first potential, and the remaining one phase is used. Since the control means for controlling the power supply conversion means is provided so as to have the second potential different from the other two phases, a sufficient amount of heat generation can be easily obtained and heating suitable for environmental conditions can be performed. It has the advantage.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an air conditioner according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram showing an example of an applied voltage according to the first embodiment.

FIG. 3 is a block diagram showing a configuration of a control unit in the first embodiment.

FIG. 4 is a block diagram showing a configuration of an air conditioning apparatus of a second embodiment according to the present invention.

FIG. 5 is a block diagram showing a configuration of a control means in the second embodiment.

[Explanation of symbols]

 1 Three-Phase AC Motor 2 Compressor 3 Control Means 4 DC Power Supply 13 Compressor Temperature Detecting Means 14 Outside Air Temperature Means

Front page continuation (72) Yoshiteru Ito Yoshiteru Ito 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Tsukasa Yoshioka, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Izumi Yoshida 4-2-5 Takaidahondori, Higashiosaka, Osaka Prefecture Matsushita Refrigerator Co., Ltd. (72) Inventor Hideo Ogata 4-2-5 Takaidahondori, East Osaka City, Osaka Prefecture Matsushita Refrigerator Co., Ltd. (72) Inventor Shusaku Watanabe 4-2-5 Takaidahondori, Higashi-Osaka City, Osaka Prefecture Matsushita Cold Machinery Co., Ltd.

Claims (4)

[Claims] 1. A power supply conversion means for converting a DC voltage into a three-phase AC voltage, a compression means for a refrigerant driven by the three-phase AC voltage converted by the power supply conversion means, and a compression means for stopping the compression means. Of the three-phase output terminals in the power conversion means, two phases have the same first potential, and the remaining one phase has the other two.
An air conditioner, comprising: a control unit that controls the power supply conversion unit so as to have a second potential different from the phase. 2. A temperature detection means for detecting the temperature of the compression means or the temperature around the compression means is provided, and the control means is responsive to the temperature detected by the temperature detection means. The air conditioner according to claim 1, wherein the second electric potential is adjusted. 3. The air conditioner according to claim 1, wherein the first electric potential in two phases is substantially equal to either positive or negative electric potential of the DC voltage. 4. The control means is further configured to sequentially switch between two phases of the first potential and one phase of the second potential at a speed at which the compression means does not drive. The air conditioner according to claim 1, 2, or 3.