CN114623567B

CN114623567B - Air conditioner

Info

Publication number: CN114623567B
Application number: CN202210255089.0A
Authority: CN
Inventors: 张俊喜; 周金伟; 徐鹏洋
Original assignee: Qingdao Hisense Hitachi Air Conditioning System Co Ltd
Current assignee: Qingdao Hisense Hitachi Air Conditioning System Co Ltd
Priority date: 2022-03-15
Filing date: 2022-03-15
Publication date: 2023-10-17
Anticipated expiration: 2042-03-15
Also published as: CN114623567A

Abstract

The application discloses an air conditioner, which is used for acquiring set preheating power and actual preheating power of a compressor when the compressor needs to be preheated; inputting the deviation between the set preheating power and the actual preheating power into a PI regulator to obtain a bias pulse width delta; the duty ratio of one phase of PWM signals is subjected to offset pulse width delta adjustment, so that the duty ratio of the phase of PWM signals is different from the duty ratio of other two phases of PWM signals, offset voltage is generated between three phases of motor voltages, direct-current offset current is further superposed on motor current, a motor winding heats, preheating of a compressor is realized, and the technical problems of high energy consumption and high cost existing in the prior art when the compressor is preheated by a heating belt are solved; moreover, the preheating power is controlled in a closed loop, so that the method is suitable for different compressors and has a wide application range.

Description

Air conditioner

Technical Field

The application relates to the technical field of air conditioning, in particular to an air conditioner.

Background

In recent years, the demand for air conditioners is expanding throughout, and particularly in northern areas, air conditioners are used for heating under winter low-temperature conditions. When the air conditioner is under outdoor low temperature condition, because lubricating oil and refrigerant mutually dissolve, if the off-line standing of off-premises station for a long time, refrigerant can deposit in the compressor crankcase in a large number, leads to lubricating oil concentration to drop, can't satisfy the compressor lubrication demand. In order to avoid damage to the compressor, the compressor needs to be preheated before starting up, so that the reliability requirement of lubricating oil after the compressor is started is met.

In order to achieve preheating of the compressor, an external electric heating belt is arranged on the outer wall of the cylinder body of the compressor in the prior art, and the electric heating belt generates heat and is conducted to compressor oil through the cylinder body by controlling the power of the electric heating belt.

The heating mode has the advantages of low heat conductivity, high heat loss, high energy consumption, low heating efficiency, long preheating period and higher cost.

Disclosure of Invention

The application provides an air conditioner, which solves the technical problems of high energy consumption and high cost existing in the prior art by preheating a compressor through a heating belt.

In order to achieve the above purpose, the application adopts the following technical scheme:

the application provides an air conditioner, comprising:

a compressor having a three-phase motor;

a power module connected with the three-phase motor;

the control module outputs a three-phase PWM signal to the power module;

the control module is further configured to:

when the compressor needs to be preheated, acquiring set preheating power and actual preheating power of the compressor;

inputting the deviation between the set preheating power and the actual preheating power into a PI regulator to obtain a bias pulse width delta;

and performing offset pulse width delta adjustment on the duty ratio of one phase PWM signal.

In some embodiments of the application, the control module is further configured to:

when the duty ratio of one phase of PWM signals is subjected to offset pulse width delta regulation, the heating value of a three-phase motor winding is calculated;

judging whether the heating value of the three-phase motor winding exceeds the set heating value;

when the heating value of the three-phase motor winding exceeds the set heating value, the phase sequence of the three-phase PWM signal is switched.

and when the adjustment time length reaches the set time length, switching the phase sequence of the three-phase PWM signals.

In some embodiments of the present application, the obtaining the set preheating power of the compressor specifically includes:

acquiring the current outdoor environment temperature;

obtaining the set preheating power corresponding to the current outdoor environment temperature according to the corresponding relation between the preset set preheating power and the outdoor environment temperature; the larger the outdoor ambient temperature is, the smaller the preheating power is set.

In some embodiments of the present application, the corresponding relationship between the set preheating power and the outdoor environment temperature is any one of a correspondence table, a linear relationship, and a linear fitting curve.

acquiring the exhaust temperature of a compressor and the outdoor environment temperature;

calculating the temperature difference between the exhaust temperature of the compressor and the outdoor environment temperature;

and obtaining the corresponding set preheating power according to the corresponding relation between the preset set preheating power and the temperature difference.

In some embodiments of the present application, the corresponding relationship between the set preheating power and the temperature difference is:

pref=k×tda+p0 when Tda is 0 and Tda is equal to or less than the temperature difference threshold;

pref=0 when Tda > temperature difference threshold;

wherein Pref is the set preheating power, tda is the temperature difference, P0 is the initial set power, and k is a constant less than 0.

before the compressor is started, acquiring outdoor environment temperature and an environment temperature limit value;

judging whether the outdoor environment temperature is greater than an environment temperature limit value;

if the outdoor ambient temperature is greater than the ambient temperature limit, determining that the compressor does not need to be preheated;

if the outdoor ambient temperature is not greater than the ambient temperature limit, it is determined that the compressor needs to be warmed up.

acquiring outdoor environment temperature, compressor exhaust temperature and environment temperature limit value in the preheating process of the compressor;

when the outdoor ambient temperature is greater than the ambient temperature limit, or the temperature difference between the compressor discharge temperature and the outdoor ambient temperature > the temperature difference threshold, it is determined that the compressor no longer needs to be warmed up.

In some embodiments of the present application, obtaining an actual preheating power of a compressor specifically includes:

obtaining a direct current bus voltage and a direct current average current of a power module;

and calculating the product of the direct current bus voltage and the direct current average current to obtain the actual preheating power of the compressor.

Compared with the prior art, the technical scheme of the application has the following technical effects: when the air conditioner needs to preheat the compressor, the set preheating power and the actual preheating power of the compressor are obtained; inputting the deviation between the set preheating power and the actual preheating power into a PI regulator to obtain a bias pulse width delta; the duty ratio of one phase of PWM signals is subjected to offset pulse width delta adjustment, so that the duty ratio of the phase of PWM signals is different from the duty ratio of other two phases of PWM signals, offset voltage is generated between three phases of motor voltages, direct-current offset current is further superposed on motor current, a motor winding heats, preheating of a compressor is realized, and the technical problems of high energy consumption and high cost existing in the prior art when the compressor is preheated by a heating belt are solved; moreover, the preheating power is controlled in a closed loop, so that the method is suitable for different compressors and has a wide application range.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic block diagram of one embodiment of an air conditioner of the present application;

FIG. 2 is a flow chart of an embodiment of a control method performed by a control module of the air conditioner of the present application;

FIG. 3 is a waveform diagram of bias pulse width modulation of the duty cycle of a U-phase PWM signal;

FIG. 4 is a flowchart of a control method performed by a control module of the air conditioner according to another embodiment of the present application;

FIG. 5 is a waveform diagram of bias pulse width modulation of the duty cycle of a V-phase PWM signal;

FIG. 6 is a flowchart illustrating a control method performed by a control module of the air conditioner according to another embodiment of the present application;

FIG. 7 is a linear fit curve of the set preheat power versus the outdoor ambient temperature;

FIG. 8 is a flowchart of a control method performed by the control module of the air conditioner according to another embodiment of the present application;

FIG. 9 is a graph showing the relationship between the set preheating power and the temperature difference;

FIG. 10 is a flowchart illustrating a control method performed by a control module of the air conditioner according to another embodiment of the present application;

fig. 11 is a flowchart illustrating a control method performed by a control module of an air conditioner according to still another embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

In the description of the present application, it should be understood that the terms "center," "upper," "lower," "front," "rear," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate description of the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be configured and operated in a particular orientation, and thus should not be construed as limiting the present application.

In the description of the present application, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.

In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present application will be understood in specific cases by those of ordinary skill in the art.

Basic operation principle of air conditioner

The air conditioner performs a refrigeration cycle by using a compressor, a condenser, an expansion valve, and an evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation, and supplies a refrigerant to the air that has been conditioned and heat exchanged.

The compressor compresses a refrigerant gas in a high-temperature and high-pressure state and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.

The expansion valve expands the liquid-phase refrigerant in a high-temperature and high-pressure state condensed in the condenser into a low-pressure liquid-phase refrigerant.

The evaporator evaporates the refrigerant expanded in the expansion valve and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor.

The evaporator may achieve a cooling effect by exchanging heat with a material to be cooled using latent heat of evaporation of a refrigerant. The air conditioner may adjust the temperature of the indoor space throughout the cycle.

The outdoor unit of the air conditioner refers to a portion including a compressor and an outdoor heat exchanger, the indoor unit of the air conditioner includes an indoor heat exchanger, and an expansion valve may be provided in the indoor unit or the outdoor unit.

The indoor heat exchanger and the outdoor heat exchanger function as a condenser or an evaporator. When the indoor heat exchanger is used as a condenser, the air conditioner is used as a heater of a heating mode, and when the indoor heat exchanger is used as an evaporator, the air conditioner is used as a cooler of a cooling mode.

The air conditioner of the embodiment further includes a compressor, a power module and a control module, as shown in fig. 1.

A compressor having a three-phase motor including three windings.

And the power module is connected with the three-phase motor and supplies power to the three-phase motor.

And the control module outputs a three-phase PWM signal to the power module, and controls the power supply of the three-phase motor through the power module.

The power module IPM comprises six transistors, see fig. 1. The control module outputs three-phase PWM signals to the control ends of the six transistors to drive the on-off of the six transistors, so that power supply for three windings of the motor is realized.

The air conditioner of the present embodiment, the control module of which is further configured to:

when the compressor needs to be preheated, acquiring set preheating power and actual preheating power of the compressor; inputting the deviation between the set preheating power and the actual preheating power into a PI regulator to obtain a bias pulse width delta; and performing offset pulse width delta adjustment on the duty ratio of one phase PWM signal.

The PI regulator is a power loop PI regulator and is used for regulating deviation between the set preheating power and the actual preheating power to obtain the bias pulse width delta.

Specifically, the control module performs the following steps, see FIG. 2.

Step S11: when the compressor needs to be preheated, the set preheating power and the actual preheating power of the compressor are obtained.

Step S12: and inputting the deviation between the set preheating power and the actual preheating power into a PI regulator to obtain the bias pulse width delta.

Step S13: and performing offset pulse width delta adjustment on the duty ratio of one phase PWM signal so that the duty ratio of the phase PWM signal is different from the duty ratio of the other two phases PWM signals.

The three-phase PWM signals generated by the control module are equal in duty ratio and are R before bias pulse width adjustment, and after the duty ratio of one phase PWM signal is subjected to bias pulse width delta adjustment, the duty ratio of the phase PWM signal is different from the duty ratio of the other two phases PWM signals. The phase duty cycle becomes R+ - δ/Tpwm, where Tpwm is the PWM period, while the other two phases PWM duty cycle remains R. The control module outputs the regulated three-phase PWM signal to the power module, and the power module supplies power to the three-phase motor, so that bias voltage is generated between the three-phase motor voltages, direct-current bias current is further superimposed on motor current, and the motor winding heats, so that the oil pool is heated. Regardless of the outdoor ambient temperature or the power supply voltage, the closed-loop control of the preheating power can be realized through the adjustment of the bias pulse width delta, so that the actual preheating power Pdc follows the set preheating power Pref.

For example, before bias pulse width adjustment is performed, the duty ratio of the U-phase PWM signal, the duty ratio of the V-phase PWM signal, and the duty ratio of the W-phase PWM signal are equal, which are all 50%; the duty ratio of the U-phase PWM signal is subjected to offset pulse width delta adjustment, as shown in fig. 3, and becomes 50% ± δ/Tpwm, where Tpwm is a PWM period, and the duty ratio of the other two phases is still 50%, offset voltages are generated between the three-phase motor voltages, and further, dc offset currents are superimposed on the motor currents, and the motor windings generate heat to perform preheating.

When the air conditioner needs to preheat the compressor, the set preheating power and the actual preheating power of the compressor are obtained; inputting the deviation between the set preheating power and the actual preheating power into a PI regulator to obtain a bias pulse width delta; the duty ratio of one phase of PWM signals is subjected to offset pulse width delta adjustment, so that the duty ratio of the phase of PWM signals is different from the duty ratio of other two phases of PWM signals, offset voltage is generated between three phases of motor voltages, direct-current offset current is further superposed on motor current, a motor winding heats, preheating of a compressor is realized, and the technical problems of high energy consumption and high cost existing in the prior art when the compressor is preheated by a heating belt are solved; moreover, the preheating power is controlled in a closed loop, so that the method is suitable for different compressors and has a wide application range.

In some embodiments of the application, the control module is further configured to perform the following steps, see fig. 4.

Step S14: and when the duty ratio of one phase of PWM signals is subjected to offset pulse width delta regulation, calculating the heating value of the three-phase motor winding.

Step S15: and judging whether the heating value of the three-phase motor winding exceeds the set heating value.

When the heating value of the three-phase motor winding exceeds the set heating value, step S16 is executed: the phase sequence of the three-phase PWM signal is switched.

Calculating the heating value of the three-phase motor winding during the bias pulse width adjustment of the duty ratio of the U-phase PWM signal; when the heating value of the three-phase motor winding exceeds the set heating value, switching the phase sequence of the three-phase PWM signal, and changing the phase sequence to the duty ratio of the V-phase PWM signal, and performing offset pulse width adjustment, as shown in fig. 5.

Calculating the heating value of the three-phase motor winding during the bias pulse width adjustment of the duty ratio of the V-phase PWM signal; when the heating value of the three-phase motor winding exceeds the set heating value, switching the phase sequence of the three-phase PWM signal, and replacing the phase sequence by performing offset pulse width adjustment on the duty ratio of the W-phase PWM signal.

Calculating the heating value of the three-phase motor winding during the bias pulse width adjustment of the duty ratio of the W-phase PWM signal; when the heating value of the three-phase motor winding exceeds the set heating value, switching the phase sequence of the three-phase PWM signal, and replacing the phase sequence to bias pulse width adjustment of the duty ratio of the U-phase PWM signal.

And (2) in the period of carrying out bias pulse width adjustment on the duty ratio of one phase of PWM signals through design steps S14 to S16, when the heating value of the windings exceeds the set heating value, switching the phase sequence of the three-phase PWM signals, avoiding uneven heating of the windings of the three-phase motor and ensuring the safety of the three-phase motor.

Assuming that the heating value is set to W1, when the product of the current actual warm-up power Pdc and the continuous heating time exceeds W1, the phase sequence replacement is performed.

Since the outdoor ambient temperature may change during the warm-up process, resulting in a change in warm-up power, phase sequence switching is performed when the accumulated value of the heat generation exceeds W1, i.e., pdc1×t1+pdc2×t2+pdc3×t3+), when W1 is exceeded.

In other embodiments of the present application, the control module is further configured to: when the duty ratio of one phase of PWM signals is subjected to offset pulse width delta regulation, the regulation time length is timed, and when the regulation time length reaches the set time length, the phase sequence of the three-phase PWM signals is switched; the three-phase motor winding is prevented from being heated unevenly, the safety of the three-phase motor is guaranteed, and the control is simple and convenient to realize.

In particular the number of the elements,

when the adjustment time length for performing offset pulse width adjustment on the duty ratio of the U-phase PWM signal reaches the set time length, switching the phase sequence of the three-phase PWM signal, and performing phase sequence replacement to perform offset pulse width adjustment on the duty ratio of the V-phase PWM signal.

When the adjustment time length for performing offset pulse width adjustment on the duty ratio of the V-phase PWM signal reaches the set time length, switching the phase sequence of the three-phase PWM signal, and performing phase sequence replacement to perform offset pulse width adjustment on the duty ratio of the W-phase PWM signal.

When the adjustment time length for performing offset pulse width adjustment on the duty ratio of the W-phase PWM signal reaches the set time length, switching the phase sequence of the three-phase PWM signal, and performing phase sequence replacement to perform offset pulse width adjustment on the duty ratio of the U-phase PWM signal.

In some embodiments of the present application, the method for obtaining the set preheating power of the compressor specifically includes the following steps, which are shown in fig. 6.

Step S21: the current outdoor ambient temperature is obtained.

Step S22: and obtaining the set preheating power corresponding to the current outdoor environment temperature according to the corresponding relation between the preset set preheating power and the outdoor environment temperature. The greater the outdoor ambient temperature, the smaller the corresponding set preheating power.

The preheating set power is configured according to the outdoor environment temperature, so that the more accurate set preheating power can be obtained, and the energy is saved.

The outdoor environment temperature is detected by the outdoor environment temperature sensor, the set preheating power is set according to the outdoor environment temperature detection value, and different preheating powers are set corresponding to different outdoor environment temperature values. As the outdoor ambient temperature increases, the preheat setting power decreases.

In some embodiments of the present application, the correspondence between the preheating power and the outdoor ambient temperature is set to be any one of a correspondence table, a linear fitting curve, and a linear relation.

In some embodiments of the present application, the correspondence between the preheating power and the outdoor environment temperature is set as a correspondence table.

The corresponding table of the set preheating power and the outdoor environment temperature is stored in the storage module of the air conditioner. When the set preheating power is required to be obtained, the corresponding table is directly inquired, and the set preheating power corresponding to the outdoor environment temperature is simply, conveniently, quickly and accurately obtained.

In some embodiments of the present application, the corresponding relationship between the preheating power and the outdoor environment temperature is a linear fitting curve.

A linear fitting curve of the set preheating power and the outdoor environment temperature is stored in a storage module of the air conditioner. When the set preheating power is required to be obtained, the corresponding set preheating power is obtained according to the linear fitting curve, and the method is simple, convenient, quick and accurate.

From the data in the correspondence table described above, a linear fitting curve can be fitted, as shown in fig. 7.

In some embodiments of the present application, the correspondence between the preheating power and the outdoor ambient temperature is set to be a linear relationship.

A linear relation between the set preheating power and the outdoor environment temperature is stored in a storage module of the air conditioner. When the set preheating power is required to be obtained, the outdoor environment temperature is substituted into the linear relation, so that the corresponding set preheating power can be simply, conveniently, quickly and accurately obtained.

The mathematical expression of the linear fitting curve is a linear relation.

For example, consider the example of 4 outdoor ambient temperature detection values, as shown in fig. 7.

Four sensed values of outdoor ambient temperature: ta1, ta2, ta3, ta4;

corresponding to four settings of preheating power: pref1, pref2, pref3, pref4;

and Ta1< Ta2< Ta3< Ta4; pref1> Pref2> Pref3> Pref4.

When the outdoor ambient temperature is less than or equal to Ta1, the preheating power is set to be Pref1, and when the outdoor ambient temperature is more than or equal to Ta4, the preheating power is set to be Pref4. The preheating setting power between different outdoor environment temperature points is obtained by adopting a linear fitting mode.

As shown in fig. 7, taw is a temperature value between Ta2 and Ta3, and a calculation formula of the set preheating power Prefw corresponding to Taw is:

Prefw=Pref2- (Taw-Ta2) *(Pref2-Pref3)/(Ta3-Ta2)。

linear fitting is performed through Ta1, ta2, ta3, ta4 and Pref1, pref2, pref3 and Pref4 to obtain a linear fitting curve, and then a linear relation is calculated.

For example, the linear relationship is the following piecewise function:

when Ta is less than or equal to Ta1, pref=pref1;

ta1< Ta is less than or equal to Ta2, pref=k1 ta+b1;

ta2< ta.ltoreq.ta 3, pref=k2 ta+b2;

ta3< ta+.ta4, pref=k3 ta+b3;

when Ta > Ta4, pref=pref4;

wherein Ta is outdoor ambient temperature, pref is set preheating power, and k1, k2, k3 are slopes, which can be calculated from Ta1, ta2, ta3, ta4 and Pref1, pref2, pref3, pref4.

In other embodiments of the present application, the method for obtaining the set preheating power of the compressor includes the following steps, which are shown in fig. 8.

Step S31: the compressor discharge temperature and the outdoor ambient temperature are obtained.

Step S32: and calculating the temperature difference between the discharge temperature of the compressor and the outdoor environment temperature.

Step S33: and obtaining the corresponding set preheating power according to the corresponding relation between the preset set preheating power and the temperature difference.

The preheating set power is configured according to the temperature difference between the exhaust temperature of the compressor and the outdoor environment temperature, so that the more accurate set preheating power can be obtained, and the energy is saved.

The set preheating power is controlled according to the outdoor ambient temperature Ta and the compressor discharge temperature Td. When Td > ta+tb, the heating is stopped. Tb represents the temperature difference where the heating has met the oil temperature requirement before the compressor is started, and Tb is referred to as a temperature difference threshold, such as 15 ℃. As the temperature difference Tda between the compressor discharge temperature Td and the outdoor ambient temperature Ta gradually approaches Tb, the warm-up setting power Pref decreases at the same time with a certain gradient. Temperature difference tda=td-Ta.

In some embodiments of the present application, the corresponding relationship between the preheating power and the temperature difference is set as follows:

pref=0 when Tda > temperature difference threshold;

wherein Pref is the set preheating power, tda is the temperature difference, P0 is the initial set power, and k is a constant less than 0. As shown in fig. 9, a corresponding relationship curve of the preheating power Pref and the temperature difference Tda is set, k being a slope.

The corresponding relation between the set preheating power and the temperature difference is stored in a storage module of the air conditioner. When the set preheating power is required to be obtained, the temperature difference between the exhaust temperature of the compressor and the outdoor environment temperature is substituted into the corresponding relation, so that the corresponding set preheating power can be simply, conveniently, quickly and accurately obtained.

Before the compressor is started, the corresponding set preheating power can be obtained according to the corresponding relation between the preset preheating power and the outdoor environment temperature; during the preheating period of the compressor, the corresponding set preheating power can be obtained according to the corresponding relation between the preset set preheating power and the temperature difference Tda; therefore, the preheating power can be accurately set, the preheating of the compressor is realized, and the waste of energy is avoided.

In some embodiments of the application, the control module is further configured to perform the following steps, see fig. 10.

Step S41: before the compressor is started, the outdoor ambient temperature and the ambient temperature limit are obtained.

The outdoor ambient temperature is detected by a temperature sensor.

The environmental temperature limit value is a preset value and is stored in the storage module.

Step S42: and judging whether the outdoor environment temperature is greater than an environment temperature limit value.

If the outdoor ambient temperature is greater than the ambient temperature limit, indicating that the outdoor ambient temperature is higher, and the compressor is not required to be preheated, then determining that the compressor is not required to be preheated.

If the outdoor ambient temperature is not greater than the ambient temperature limit, indicating that the outdoor ambient temperature is low and the compressor needs to be warmed up, determining that the compressor needs to be warmed up.

After it is determined that the compressor needs to be warmed up, execution of step S11 and subsequent steps is resumed.

Through the design steps S41-S42, whether the compressor needs to be preheated or not is judged according to the outdoor environment temperature and the environment temperature limit value, judgment is accurate, the compressor is reasonably preheated, and energy is saved.

In still other embodiments of the present application, the control module is further configured to perform the following steps, see FIG. 11.

Step S51: in the preheating process of the compressor, the outdoor environment temperature, the exhaust temperature of the compressor and the limit value of the environment temperature are obtained.

Step S52: when the outdoor ambient temperature is greater than the ambient temperature limit, or the temperature difference between the compressor discharge temperature and the outdoor ambient temperature > the temperature difference threshold, it is determined that the compressor no longer needs to be warmed up.

And stopping heating when the compressor is judged to be no longer required to be preheated.

In the preheating process of the compressor, when the outdoor environment temperature is greater than the environment temperature limit value or the temperature difference between the exhaust temperature of the compressor and the outdoor environment temperature is greater than the temperature difference threshold value, the compressor is not required to be preheated, and the heating is stopped, so that energy sources are saved.

The data collected by the outdoor environment temperature sensor can be obtained by other controllers or devices and then sent to the control module of the application in a communication mode. Or other controllers or devices set the set preheating power according to the outdoor environment temperature detection value detected by the outdoor environment temperature sensor, and then send the set preheating power to the control module of the application in a communication mode.

(1) Firstly, the direct current bus voltage Vdc and the direct current average current Idc of the power module are obtained.

(2) And then calculating the product of the direct current bus voltage Vdc and the direct current average current Idc to obtain the actual preheating power Pdc of the compressor. Pdc=vdc×idc.

The control module is provided with a voltage sampling circuit and a current sampling circuit for detecting the DC bus voltage Vdc and the DC average current Idc of the power module, as shown in fig. 1.

The actual preheating power Pdc is obtained through the direct-current bus voltage Vdc and the direct-current average current Idc, the calculation method is simple, and the actual preheating power Pdc can be timely and accurately obtained.

The air conditioner disclosed by the application is suitable for different outdoor environment temperatures and compressors by performing heating control on the compressor windings in a power closed-loop mode.

The air conditioner of the application introduces power loop control, and performs power closed loop control by adopting a method of electromagnetic heating and bias direct current superposition, thus being applicable to different compressors and being capable of considering different power supply input voltages.

In the description of the above embodiments, particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples. The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present application should be included in the scope of the present application. Therefore, the protection scope of the application is subject to the protection scope of the claims.

Claims

1. An air conditioner, comprising:

a compressor having a three-phase motor;

a power module connected with the three-phase motor;

the control module outputs a three-phase PWM signal to the power module;

the method is characterized in that: the control module is further configured to:

and performing offset pulse width delta adjustment on the duty ratio of one phase PWM signal so that the duty ratio of the phase PWM signal is different from the duty ratio of the other two phases PWM signals.

2. An air conditioner according to claim 1, wherein: the control module is further configured to:

3. An air conditioner according to claim 1, wherein: the control module is further configured to:

4. An air conditioner according to claim 1, wherein: the obtaining the set preheating power of the compressor specifically comprises the following steps:

acquiring the current outdoor environment temperature;

5. An air conditioner according to claim 4, wherein: the corresponding relation between the set preheating power and the outdoor environment temperature is any one of a corresponding table, a linear relation and a linear fitting curve.

6. An air conditioner according to claim 1, wherein: the obtaining the set preheating power of the compressor specifically comprises the following steps:

7. An air conditioner according to claim 6, wherein: the corresponding relation between the set preheating power and the temperature difference is as follows:

pref=0 when Tda > temperature difference threshold;

8. An air conditioner according to claim 1, wherein: the control module is further configured to:

9. An air conditioner according to claim 1, wherein: the control module is further configured to:

10. The air conditioner according to any one of claims 1 to 9, wherein: the method for obtaining the actual preheating power of the compressor specifically comprises the following steps: