Control method of variable frequency heat pump water heater

Abstract

The invention discloses a control method of a variable-frequency heat pump water heater, which comprises the following steps of: after the variable-frequency heat pump water heater is started, controlling the operation frequency of a compressor by taking the difference value between the actual water temperature of a water tank and the set water temperature, the variation of the water temperature in the heating process and the difference value between the high pressure of a system and the actual water temperature of the water tank as conditions. The operation frequency of the compressor is more accurately controlled, and the energy consumption is reduced while the water demand of a user is met.

Description

Technical Field

[0001] The invention relates to a control method for a variable frequency heat pump water heater. Background Art

[0002] As air source heat pump water heaters gradually enter thousands of households, users have higher and higher requirements for product comfort. At present, a large number of household fixed-frequency heat pump water heaters are used in the market. Since the operating frequency of fixed-frequency water heaters cannot be changed, the output capacity of the unit is basically constant when the external ring temperature remains unchanged, which cannot meet the user's demand for rapid heating. In addition, when the water temperature is high, the operating power of the fixed-frequency water heater is too large, and it is impossible to achieve a good energy-saving effect. Summary of the invention

[0003] In view of the above problems, the present invention provides a control method for a variable frequency heat pump water heater, which effectively solves the problems pointed out in the background technology.

[0004] The technical solution adopted by the present invention is:

[0005] A control method for a variable frequency heat pump water heater is provided. After the variable frequency heat pump water heater is started, the control is performed in the following manner:

[0006] 1) When it is detected that Tsx≤Tset-△T1, the compressor is controlled to operate at high frequency for rapid heating, and the following control is performed:

[0007] 11) When it is detected that Tsx-Tsxn≤△t1 and Tpq-Tsx≤a, the compressor is controlled to operate at a high frequency;

[0008] 12) When it is detected that Tsx-Tsxn>△t2 and Tpq-Tsx>a, the compressor is controlled to operate at the optimal frequency;

[0009] 2) When it is detected that Tsx≤Tset-△T2 and lasts for 1 minute, the compressor is controlled to operate at the optimal frequency to ensure stable heating and optimal energy efficiency, and the following control is performed;

[0010] 21) When it is detected that Tsx-Tsxn≤△t3 and Tpq-Tsx≤a, the compressor is controlled to operate at a high frequency;

[0011] 22) When it is detected that Tsx-Tsxn≤△t1 and Tpq-Tsx≤a, the compressor is controlled to operate at the optimal frequency;

[0012] 23) When it is detected that Tsx-Tsxn>△t2 and Tpq-Tsx>b, the compressor is controlled to operate at a low frequency;

[0013] 3) When it is detected that Tsx≤Tset-△T3 and lasts for 1 minute, the compressor is controlled to run at low frequency, heat slowly, keep the unit quiet and stable, and perform the following control:

[0014] 31) When it is detected that Tsx-Tsxn≤△t3 and Tpq-Tsx≤a, the compressor is controlled to operate at the optimal frequency;

[0015] 32) When it is detected that Tsx-Tsxn≤△t1, the compressor is controlled to operate at a low frequency;

[0016] 4) When it is detected that Tsx ≥ Tset, the compressor is controlled to shut down;

[0017] in:

[0018] Tsx: current water temperature of the water tank;

[0019] Tset: water tank set temperature;

[0020] Tsxn: water temperature in the water tank before time s;

[0021] Tpq: exhaust saturation temperature of the compressor;

[0022] △T1, △T2, △T3, △t1, △t2, △t3, a, and b are all constants, and △T1>△T2>△T3>0, △t2>△t1>0>△t3, a <b。

[0023] The present invention uses the difference between the actual water temperature of the water tank and the set water temperature, the change in water temperature during the heating process, and the difference between the system high pressure and the actual water temperature of the water tank as conditions to control the operating frequency of the compressor, thereby being able to more accurately control the operating frequency of the compressor, thereby reducing energy consumption while meeting the water needs of users. DETAILED DESCRIPTION

[0024] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0025] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0026] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

[0027] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0029] The present invention is further described in detail below through specific examples.

[0030] Example 1

[0031] A control method for a variable frequency heat pump water heater is provided. After the variable frequency heat pump water heater is started, the control is performed in the following manner:

[0032] 1) When it is detected that Tsx≤Tset-△T1, it means that the actual water temperature of the water tank is significantly different from the set water temperature. The compressor is controlled to operate at a high frequency for rapid heating and the following control is performed:

[0033] 11) When it is detected that Tsx-Tsxn≤△t1 and Tpq-Tsx≤a, it means that the water temperature in the water tank rises slowly (it can be considered that the user is using hot water) and the system high pressure is not high. At this time, the compressor is controlled to operate at a high frequency to achieve rapid heating;

[0034] 12) When it is detected that Tsx-Tsxn>△t2 and Tpq-Tsx>a, it means that the water temperature in the water tank rises quickly (it can be considered that the user does not use hot water), and the system high pressure is not too high. At this time, the compressor is controlled to operate at the optimal frequency to improve energy efficiency and ensure that the system high pressure will not be too high;

[0035] 2) When Tsx≤Tset-△T2 is detected and lasts for 1 minute, it means that the actual water temperature of the water tank is not much different from the set water temperature. The compressor is controlled to operate at the optimal frequency to ensure stable heating and optimal energy efficiency, and the following control is performed;

[0036] 21) When it is detected that Tsx-Tsxn≤△t3 and Tpq-Tsx≤a, it means that the water temperature in the water tank is reduced (it can be considered that the user is using hot water), and the system high pressure is not high, the compressor is controlled to operate at a high frequency to achieve rapid heating, to prevent the water temperature in the water tank from continuing to decrease and affecting the user experience;

[0037] 22) When it is detected that Tsx-Tsxn≤△t1 and Tpq-Tsx≤a, it means that the water temperature in the water tank rises slowly (it can be considered that the user does not use hot water), and the system high pressure is not too high. The compressor is controlled to operate at the optimal frequency to ensure stable heating and optimal energy efficiency;

[0038] 23) When it is detected that Tsx-Tsxn>△t2 and Tpq-Tsx>b, it means that the water temperature in the water tank rises quickly (it can be considered that the user does not use hot water), and the system high pressure is too high (it can be considered that the heat exchange of the unit is not good). At this time, the compressor is controlled to run at a low frequency to ensure that the compressor does not have a high-pressure fault, and to achieve slow heating and reduce noise;

[0039] 3) When Tsx≤Tset-△T3 is detected and lasts for 1 minute, it means that the water temperature in the water tank is slightly different from the set water temperature. The compressor is controlled to operate at a low frequency and heat slowly to keep the unit quiet and stable, and the following controls are performed:

[0040] 31) When it is detected that Tsx-Tsxn≤△t3 and Tpq-Tsx≤a, it means that the water temperature in the water tank is reduced (it can be considered that the user is using hot water), and the system high pressure is not high. At this time, the compressor is controlled to operate at the optimal frequency to achieve stable heating and improve energy efficiency;

[0041] 32) When it is detected that Tsx-Tsxn≤△t1, it means that the water temperature in the water tank rises slowly (it can be considered that the user does not use hot water). At this time, the compressor is controlled to operate at a low frequency (when the water temperature is about to reach the set water temperature, low-frequency operation can ensure that the system high pressure is not too high), slowly heat up, and reduce noise;

[0042] 4) When it is detected that Tsx ≥ Tset, the compressor is controlled to shut down;

[0043] in:

[0044] Tsx: current water temperature of the water tank;

[0045] Tset: water tank set temperature;

[0046] Tsxn: water temperature in the water tank before time s;

[0047] Tpq: exhaust saturation temperature of the compressor;

[0048] △T1, △T2, △T3, △t1, △t2, △t3, a, and b are all constants, and △T1>△T2>△T3>0, △t2>△t1>0>△t3, a <b。

[0049] Finally, it should be noted that the above examples are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A control method for a variable frequency heat pump water heater, characterized in that: After the variable frequency heat pump water heater is turned on, it is controlled as follows: 1) When it is detected that Tsx≤Tset-△T1, the compressor is controlled to operate at high frequency for rapid heating, and the following control is performed: 11) When it is detected that Tsx-Tsxn≤△t1 and Tpq-Tsx≤a, the compressor is controlled to operate at a high frequency; 12) When it is detected that Tsx-Tsxn>△t2 and Tpq-Tsx>a, the compressor is controlled to operate at the optimal frequency; 2) When it is detected that Tsx≤Tset-△T2 and lasts for 1 minute, the compressor is controlled to operate at the optimal frequency to ensure stable heating and optimal energy efficiency, and the following control is performed; 21) When it is detected that Tsx-Tsxn≤△t3 and Tpq-Tsx≤a, the compressor is controlled to operate at a high frequency; 22) When it is detected that Tsx-Tsxn≤△t1 and Tpq-Tsx≤a, the compressor is controlled to operate at the optimal frequency; 23) When it is detected that Tsx-Tsxn>△t2 and Tpq-Tsx>b, the compressor is controlled to operate at a low frequency; 3) When it is detected that Tsx≤Tset-△T3 and lasts for 1 minute, the compressor is controlled to run at low frequency, heat slowly, keep the unit quiet and stable, and perform the following control: 31) When it is detected that Tsx-Tsxn≤△t3 and Tpq-Tsx≤a, the compressor is controlled to operate at the optimal frequency; 32) When it is detected that Tsx-Tsxn≤△t1, the compressor is controlled to operate at a low frequency; 4) When it is detected that Tsx≥Tset, the compressor is controlled to be turned off; in: Tsx: current water temperature of the water tank; Tset: water tank set temperature; Tsxn: water temperature in the water tank before time s; Tpq: exhaust saturation temperature of the compressor; △T1, △T2, △T3, △t1, △t2, △t3, a, and b are all constants, and △T1>△T2>△T3>0, △t2>△t1>0>△t3, a <b。