KR20040050475A - Control method for heat pump - Google Patents

Abstract

PURPOSE: A method for controlling a heat pump system applying a plurality of compressors is provided to stabilize an indoor temperature by accurately sensing a load by sensing the indoor temperature after stopping a plurality of compressors at the same time. CONSTITUTION: A plurality of compressors are operated at the same time to quickly reach a desired temperature(S21). If a temperature reaches the desired temperature, the plurality of compressors are stopped at the same time(S22-S23). The plurality of compressors maintain an operation standby state for a predetermined time to be operated again(S24). An indoor temperature is measured during the operation standby state. The measured indoor temperature is compared with the desired temperature(S26). If a difference between the indoor temperature and the desired temperature exceeds a set value, the plurality of compressors are operated at the same time(S27). If the difference is within the set value, some compressors are selectively operated(S28).

Description

Control method for heat pump system using multiple compressors {Control method for heat pump}

The present invention relates to a method for controlling a heat pump system using a plurality of compressors, and more particularly, a plurality of compressors in which the plurality of compressors are selectively operated or simultaneously operated according to a difference between an indoor temperature and a desired temperature after the plurality of compressors are turned off. The present invention relates to a control method of an applied heat pump system.

In general, a heat pump system includes a compressor for converting a gaseous refrigerant at low temperature and low pressure into a gaseous state refrigerant at high temperature and high pressure, and a condenser for converting a gaseous state refrigerant at high temperature and high pressure changed into a liquid refrigerant at medium temperature and high pressure. And an expansion device for changing the medium-temperature high-pressure liquid state refrigerant in the condenser into a low-temperature low-pressure liquid state refrigerant, and a four-way valve for changing the flow path of the refrigerant according to a cooling and heating mode.

In the heat pump system, the indoor heat exchanger and the outdoor heat exchanger have different roles depending on the cooling and heating mode.In the heating mode, the indoor heat exchanger plays the role of a condenser and the outdoor heat exchanger plays the role of an evaporator. And the outdoor heat exchanger acts as a condenser.

In addition, recently, by applying a plurality of compressors to be able to vary the capacity according to the cooling load or heating load to optimize the cooling and heating efficiency, the capacity of the plurality of compressors are the same or according to the use and needs Will have different capacities.

For example, if the heat pump system has two compressors, and the refrigerant compression capacity is 40% and 60%, respectively, the two compressors are operated simultaneously when the cooling or heating load is large, resulting in 100% refrigerant compression. If the cooling or heating load is small, either one of the two compressors can be selectively operated to enable a refrigerant compression of 40% or 60%.

1 is a flowchart illustrating a method for controlling a heat pump system using a plurality of compressors according to the related art, in which a plurality of compressors are simultaneously operated in order to quickly reach a desired temperature set by a user in a first step. Reference)

That is, when the compressor is composed of two having a refrigerant compression capacity of 40% and 60%, the two compressors are operated at the same time as a predetermined number of times to have cooling or heating performed with a refrigerant compression capacity of 100%.

The second stage selectively activates some of the plurality of compressors when the desired temperature is reached in the first stage (see S2 and S3).

For example, when the desired temperature is reached, the compressor having the refrigerant compression capacity of 60% is stopped, and only the compressor having the refrigerant compression capacity of 40% is selectively operated.

In the third stage, when the cooling or heating load is eliminated while the compressor is selectively operated in the second stage, that is, the error between the room temperature and the desired temperature does not occur, only the compressor operated in the second stage is selectively operated. See S4 and S5)

If the cooling or heating load is not canceled by the compressor selectively operated in the second step in the third step, the plurality of compressors are simultaneously operated to eliminate the cooling or heating load.

However, the method of controlling a heat pump system using a plurality of compressors according to the related art as described above selectively determines only some compressors because it determines whether cooling or heating loads are resolved while some of the plurality of compressors are selectively operated. If the cooling time or heating load rapidly increases or decreases within approximately three minutes, that is, the time required for pressure equalization for restarting a stationary compressor, the room temperature control becomes unstable. There is a problem.

The present invention has been made to solve the above problems of the prior art, the object of which is to operate a plurality of compressors at the same time to reach the desired temperature and then to stop the plurality of compressors at the same time to determine the error between the room temperature and the desired temperature Accordingly, since the cooling or heating load can be sensed more accurately by determining whether the plurality of compressors are selected or simultaneously operated, the heat pump system using a plurality of compressors to stably control the indoor temperature to improve the comfort of the room. To provide a control method.

1 is a flow chart showing a heat pump system control method according to the prior art,

2 is a configuration diagram showing a configuration of a heat pump system to which a plurality of compressors are applied;

3 is a flowchart illustrating a method of controlling a plurality of heat pump systems according to the present invention;

Figure 4 is a state diagram showing the operation state of the compressor according to the room temperature in a plurality of heat pump system control method according to the present invention.

According to a feature of a method for controlling a heat pump system using a plurality of compressors according to the present invention for solving the above problems, a first step of simultaneously operating a plurality of compressors until the desired temperature is reached during heating operation of the heat pump system And a second step in which the plurality of compressors are stopped simultaneously when the desired temperature is reached in the first step, a third step in which an indoor temperature is sensed after the compressor is stopped in the second step, and a room detected in the third step. And a fourth step in which the plurality of compressors are selected or simultaneously operated according to the difference between the temperature and the desired temperature.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram illustrating a heating cycle of a heat pump system employing a plurality of compressors, and includes first and second compressors 11 and 12 having different capacities for compressing a refrigerant into a gas refrigerant having a high temperature and high pressure. An indoor heat exchanger 14 for condensing the refrigerant compressed by the first and second compressors 11 and 12 with indoor air to condense it into a liquid refrigerant of medium temperature and high pressure, and the refrigerant passing through the indoor heat exchanger 14 at low temperature and low pressure. Expansion valve 15 for reducing the pressure with liquid refrigerant, an outdoor heat exchanger 16 for exchanging the refrigerant passing through the expansion valve 15 with outdoor air, and a refrigerant having passed through the outdoor heat exchanger 16. And an accumulator 17 which separates the liquid refrigerant from the phase and supplies only the gas refrigerant to the first and second compressors 11 and 12.

In addition, the heat pump system using the two compressors includes check valves 11a and 12a for preventing backflow of the compressed refrigerant of the first and second compressors 11 and 12, and the first and second compressors 11. And a four-way valve 13 for changing the role of the heat exchanger by switching the flow path of the refrigerant having passed through 12).

Compressor control method according to the cooling or heating load in the heat pump system to which the plurality of compressors configured as described above is shown in Fig. 3, first, in order to quickly reach the desired temperature set by the user in the first step Is activated simultaneously (see S21).

That is, since the first and second compressors 11 and 12 have the refrigerant compression capacities of 40% and 60%, respectively, and operate at the same time, the refrigerant compression capacities can be changed according to use and need.

In the second step, when the desired temperature is reached by the plurality of compressors operated in the first step, the plurality of compressors are stopped at the same time (see S22 and S23).

In the third stage, the plurality of compressors stopped in the second stage are kept in operation standby state for a predetermined time to be restarted (see S24).

In other words, the first and second compressors 11 and 12 stopped in the second stage are required to balance pressure for restarting, and are kept in a stand-by state for three minutes during which the pressure balance takes place. Therefore, while the first and second compressors 11 and 12 maintain the operating standby state, the room temperature gradually increases during cooling and the room temperature gradually decreases during heating, thereby changing the cooling or heating load. .

In the fourth step, the indoor temperature is sensed while the plurality of compressors are in the operation standby state (see S25).

The fifth step compares the room temperature detected in the fourth step with the desired temperature, and simultaneously operates the plurality of compressors when the error exceeds the set value (see S26 and S27).

If the error is within the set value in the fifth step, some of the plurality of compressors are selectively operated. (See S28.)

For example, the heating temperature is 3 ?? compared to the desired temperature during heating operation. In the case of lowering below, the first and second compressors 11 and 12 are operated simultaneously, and the indoor temperature is 3 ?? In the case of descending within, only the second compressor 12 is selectively operated.

In the heat pump system control method using a plurality of compressors according to the present invention as described above in more detail with reference to Figure 4 the operation state of the compressor according to the room temperature, during the initial operation of the heat pump system or a sudden load change Multiple compressors are run simultaneously (C1) two times in order to reach the desired temperature quickly.

At this time, the desired temperature range during the heating operation of the heat pump system to which the plurality of compressors are applied has a range of temperature from the first set value lower than the desired temperature to the second set value higher than the desired temperature based on the desired temperature. The first set point has a larger size than the second set point. For example, the first set point has a 3 ?? And the second setpoint is 0.5 ?? Is set to.

Therefore, when the plurality of compressors are simultaneously operated (C1) two times and the room temperature (20) is lowered (21) to the first set value or higher than the desired temperature (21), the plurality of compressors are simultaneously operated (C2) again two times. The load is released.

Meanwhile, when the load is released, some of the plurality of compressors are selectively operated (C3).

Heat pump system control method applying a plurality of compressors according to the present invention is configured as described above in order to quickly respond to the initial operation of the heat pump system or a sudden load change by simultaneously operating a plurality of compressors to remove the load after the plurality of compressors By stopping and sensing the indoor temperature during the operation standby state required for the plurality of compressors to be restarted, and determining a difference between the desired temperature and determining the selective or simultaneous operation of the plurality of compressors according to the determination result. In addition, by stopping a plurality of compressors at the same time to detect the room temperature more accurate load can be detected, not only to stabilize the room temperature, but also to improve the comfort of the room.

Claims (3)

A first step in which a plurality of compressors are operated simultaneously until a desired temperature is reached during heating operation of the heat pump system; A second step of simultaneously stopping the plurality of compressors when the desired temperature is reached in the first step; A third step of detecting a room temperature after the compressor stop in the second step; And a fourth step of selectively operating or simultaneously operating the plurality of compressors according to a difference between the room temperature sensed in the third step and the desired temperature. The method of claim 1, The fourth step is a first process of determining the error between the room temperature and the desired temperature, And a second step of simultaneously operating the plurality of compressors when the indoor temperature drops below a predetermined temperature as a result of the determination of the first step. Control method. The method of claim 2, The fourth step further comprises the step of selectively operating some of the plurality of compressors when the indoor temperature is lowered within the set temperature compared to the desired temperature heat pump system using a plurality of compressors, characterized in that Control method.