CN103684001B - The control method of power switch and device in convertible frequency air-conditioner - Google Patents

Abstract

The embodiment of the present invention provides control method and the device of power switch in a kind of convertible frequency air-conditioner, calculate pole tension according to three-phase voltage, and described pole tension is loaded on power switch, realize the control to power switch, compared with existing power switch control method, described method directly utilizes pole tension to realize the control to power switch upper and lower bridge arm closure or conducting, because pole tension calculates according to three-phase voltage, thereby the upper and lower bridge arm that makes power switch has certain conducting or closed retention time in whole voltage cycle, but not whole voltage cycle all moves, so reduced the on-off times of power switch, the wearing and tearing of power switch are alleviated.

Description

Control method and device for power switch in frequency conversion air conditioner

technical field

The invention relates to the field of control, in particular to a method and device for controlling a power switch in an inverter air conditioner.

Background technique

At present, frequency conversion air conditioners are used more and more frequently. The intelligent power module of the frequency conversion air conditioner is its core part. The intelligent power module includes a power switch. The power switch of the frequency conversion air conditioner is usually controlled by the space voltage vector pulse width modulation method, namely: through The sector judgment determines the basic turn-on time of the adjacent voltage vectors of the sector, and controls the power switch IGBT to perform uninterrupted turn-on and turn-off in the entire phase voltage cycle according to the duty cycle, so the switching times of the power switch IGBT are frequent and easy Wear occurs and thus affects the service life of the air conditioner.

Contents of the invention

In view of this, the present invention provides a control method and device for a power switch of an inverter air conditioner, aiming to solve the problem that the existing control method for a power switch of an inverter air conditioner is easy to wear the power switch, thereby affecting the service life of the air conditioner.

In order to achieve the above object, the embodiment of the present invention provides the following technical solutions:

A method for controlling a power switch of an inverter air conditioner, comprising:

Determine whether the preset conditions are met;

When the preset conditions are met, the voltage in the two-phase rotating coordinate system is converted into a three-phase voltage;

Calculate the pole voltage according to the three-phase voltage and a preset calculation rule;

The pole voltage is supplied to the power switch to realize the control of the power switch.

Preferably, the calculation of the pole voltage according to the three-phase voltage and preset calculation rules includes:

Comparing the magnitudes of the three-phase voltages at the current moment, and determining the maximum voltage value, the minimum voltage value and the intermediate voltage value among the three-phase voltages at the current moment;

calculating the sum of the maximum voltage value and the minimum voltage value;

When the sum of the maximum voltage value and the minimum voltage value is greater than or equal to zero, determine that the pole voltage is the difference between a preset value and the maximum voltage value;

When the sum of the maximum voltage value and the minimum voltage value is less than zero, the pole voltage is determined to be the difference between a preset value and the minimum voltage value.

Preferably, the preset values include:

Half of the bus voltage value.

Preferably, the preset conditions include:

The outdoor ambient temperature is greater than the preset temperature value.

Preferably, the preset conditions include:

empty condition.

A control device for a power switch of an inverter air conditioner, comprising:

A judging module, configured to judge whether a preset condition is met;

The voltage conversion module is used to convert the voltage in the two-phase rotating coordinate system into a three-phase voltage when the preset condition is met;

a calculation module, configured to calculate the pole voltage according to the three-phase voltage and a preset calculation rule;

The control module is used to supply the pole voltage to the power switch to control the power switch.

Preferably, the calculation module includes:

A comparing unit, configured to compare the magnitudes of the three-phase voltages at the current moment, and determine the maximum voltage value, the minimum voltage value and the intermediate voltage value among the three-phase voltages at the current moment;

an adding unit, configured to calculate the sum of the maximum voltage value and the minimum voltage value;

a pole voltage determining unit, configured to determine that the pole voltage is the difference between a preset value and the maximum voltage value when the sum of the maximum voltage value and the minimum voltage value is greater than or equal to zero; when the maximum voltage When the sum of the value and the minimum voltage value is less than zero, the pole voltage is determined to be the difference between the preset value and the minimum voltage value.

In the method and device for controlling the power switch in the inverter air conditioner described in the embodiments of the present invention, the pole voltage is calculated according to the three-phase voltage, and the pole voltage is loaded on the power switch to realize the control of the power switch. Compared with the switch control method, the method directly uses the pole voltage to control the closing or conducting of the upper and lower bridge arms of the power switch. It has a certain on-off or off-hold time, instead of operating in the entire voltage cycle, so the switching times of the power switch are reduced, and the wear of the power switch is reduced.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

FIG. 1 is a flowchart of a control method for a power switch of an inverter air conditioner disclosed in an embodiment of the present invention;

2 is a flow chart of a method for calculating pole voltages according to the three-phase voltages and preset calculation rules in a method for controlling a power switch of an inverter air conditioner disclosed in an embodiment of the present invention;

Fig. 3 is an effect diagram after the pole voltage calculated in the method for controlling the power switch of the inverter air conditioner disclosed in the embodiment of the present invention is supplied to the power switch;

FIG. 4 is a schematic diagram of the number of conduction or closure times of the power switch caused by the traditional power switch control method and the power switch control method described in this embodiment;

Fig. 5 is a schematic structural diagram of a control device for a power switch of an inverter air conditioner disclosed in an embodiment of the present invention;

Fig. 6 is a schematic structural diagram of a calculation module in a control device for a power switch of an inverter air conditioner disclosed in an embodiment of the present invention.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The embodiment of the present invention discloses a method for controlling a power switch of an inverter air conditioner, as shown in FIG. 1 , including:

S101: judging whether a preset condition is met;

S102: When the preset condition is met, convert the voltage in the two-phase rotating coordinate system into a three-phase voltage;

When the preset conditions are not met, it ends.

S103: Calculate the pole voltage according to the three-phase voltage and a preset calculation rule;

The pole voltage is the terminal voltage supplied to the power switch.

The specific calculation process is shown in Figure 2, which may include:

S201: Comparing the magnitudes of the three-phase voltages at the current moment, and determining the maximum voltage value, the minimum voltage value, and the intermediate voltage value among the three-phase voltages at the current moment;

In this embodiment, the maximum voltage value is recorded as V _max , the minimum voltage value is recorded as V _min , and the intermediate voltage value is recorded as V _mid .

S202: Calculate the sum of the maximum voltage value and the minimum voltage value;

That is, V _max +V _min is calculated.

S203: judging whether V _max +V _min is less than zero;

S204: When the sum of the maximum voltage value and the minimum voltage value is greater than or equal to zero, determine that the pole voltage is the difference between a preset value and the maximum voltage value;

The preset value in this embodiment is preferably the bus voltage, denoted as V _DC , that is, the pole voltage

S205: When the sum of the maximum voltage value and the minimum voltage value is less than zero, determine that the pole voltage is the difference between a preset value and the minimum voltage value, that is, the pole voltage

S104: Supply the pole voltage to the power switch, so as to control the power switch.

From the calculation rules of the above-mentioned pole voltage, it can be seen that after the calculated pole voltage is supplied to the power switch, the direct effect is shown in Figure 3. A voltage cycle is divided into 6 equal parts, and in the intervals of 30 degrees before and after the peak, The upper bridge arm of the power switch is always in the conduction state, while the lower bridge arm of the power switch is always in the conduction state in the interval of 30 degrees before and after including the trough, that is to say, in the interval including the peak or trough, the power The bridge arm of the switch remains on, and one voltage cycle includes two such intervals. Therefore, within one voltage cycle, the power switch remains on in two 60-degree intervals, so it is different from the existing control method. than, reducing the switching times by one-third.

FIG. 4 is a schematic diagram of the power switch conduction or closing times caused by the traditional power switch control method and the power switch control method described in this embodiment, wherein the SVPWM method is a traditional power switch control method. It can be seen that the SVPWM method is used throughout the power switch control method. The voltage cycle power switch operates uninterruptedly, as shown in 401 , but using the method described in this embodiment, there is an interval 402 in which the power switch does not operate (conduction or closure).

From the above analysis, it can be seen that the method described in this embodiment calculates the pole voltage based on the three-phase voltage, and supplies the pole voltage to the power switch, so that two 60-degree intervals near the peak and valley of the phase voltage are forced Turn on or off the switch to reduce the power switch loss by 1/3, and the compressor can still run smoothly, thereby reducing the wear of the power switch and saving electric energy.

Further, the preset conditions described in this embodiment are specifically:

The outdoor ambient temperature is greater than the preset temperature value, that is, when the outdoor ambient temperature is greater than the preset temperature value, the above control method for the power switch is executed, and when the outdoor ambient temperature is not greater than the preset temperature value, the traditional A control method for a power switch.

Alternatively, the preset condition may be an empty condition, that is, regardless of the outdoor temperature, the power switch control method in this embodiment is always used in the inverter air conditioner.

In actual use, preset conditions may be selected according to different requirements, which are not limited here.

Corresponding to the above method embodiment, the embodiment of the present invention also discloses a control device for the power switch of the inverter air conditioner, as shown in FIG. 5 , including:

A judging module 501, configured to judge whether a preset condition is met;

A voltage conversion module 502, configured to convert the voltage in the two-phase rotating coordinate system into a three-phase voltage when a preset condition is met;

A calculation module 503, configured to calculate the pole voltage according to the three-phase voltage and a preset calculation rule;

The control module 504 is configured to supply the pole voltage to the power switch to control the power switch.

The working process of the device described in this embodiment is: the judging module judges whether the preset condition is satisfied, if so, the voltage conversion module converts the voltage under the two-phase rotating coordinate system into a three-phase voltage, and the calculation module is based on the three-phase voltage and a preset calculation rule to calculate the pole voltage, and the control module supplies the pole voltage to the power switch to realize the control of the power switch.

The device described in this embodiment includes a calculation module for calculating the pole voltage and a control module for supplying the pole voltage to the power switch and realizing the control of the power switch, and realizes forcing the pole voltage to be near the peak and valley of the phase voltage respectively. The two 60-degree intervals turn on or off the switch, which reduces the power switch loss by 1/3, and the compressor can still run smoothly, thereby reducing the wear of the power switch and saving electric energy.

Further, the calculation module described in this embodiment is shown in Figure 6, including:

A comparing unit 601, configured to compare the magnitudes of the three-phase voltages at the current moment, and determine the maximum voltage value, the minimum voltage value, and the intermediate voltage value among the three-phase voltages at the current moment;

an adding unit 602, configured to calculate the sum of the maximum voltage value and the minimum voltage value;

a pole voltage determining unit 603, configured to determine that the pole voltage is the difference between a preset value and the maximum voltage value when the sum of the maximum voltage value and the minimum voltage value is greater than or equal to zero; When the sum of the voltage value and the minimum voltage value is less than zero, the pole voltage is determined to be the difference between a preset value and the minimum voltage value.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same or similar parts of each embodiment can be referred to each other.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (5)

1. A control method for an inverter air conditioner power switch, characterized in that it comprises: Determine whether the preset conditions are met; When the preset conditions are met, the voltage in the two-phase rotating coordinate system is converted into a three-phase voltage; Calculate the pole voltage according to the three-phase voltage and a preset calculation rule; supplying the pole voltage to the power switch to control the power switch; Wherein, the calculation of the pole voltage according to the three-phase voltage and preset calculation rules includes: Comparing the magnitudes of the three-phase voltages at the current moment, and determining the maximum voltage value, the minimum voltage value and the intermediate voltage value among the three-phase voltages at the current moment; calculating the sum of the maximum voltage value and the minimum voltage value; When the sum of the maximum voltage value and the minimum voltage value is greater than or equal to zero, determine that the pole voltage is the difference between a preset value and the maximum voltage value; When the sum of the maximum voltage value and the minimum voltage value is less than zero, the pole voltage is determined to be the difference between a preset value and the minimum voltage value. 2. The method according to claim 1, wherein the preset value comprises: Half of the bus voltage value. 3. The method according to claim 1, wherein the preset conditions include: The outdoor ambient temperature is greater than the preset temperature value. 4. The method according to claim 1, wherein the preset conditions include: empty condition. 5. A control device for an inverter air conditioner power switch, characterized in that it comprises: A judging module, configured to judge whether a preset condition is met; The voltage conversion module is used to convert the voltage in the two-phase rotating coordinate system into a three-phase voltage when the preset condition is met; a calculation module, configured to calculate the pole voltage according to the three-phase voltage and a preset calculation rule; a control module, configured to supply the pole voltage to the power switch to control the power switch; Wherein, the calculation module includes: A comparing unit, configured to compare the magnitudes of the three-phase voltages at the current moment, and determine the maximum voltage value, the minimum voltage value and the intermediate voltage value among the three-phase voltages at the current moment; an adding unit, configured to calculate the sum of the maximum voltage value and the minimum voltage value; a pole voltage determining unit, configured to determine that the pole voltage is the difference between a preset value and the maximum voltage value when the sum of the maximum voltage value and the minimum voltage value is greater than or equal to zero; when the maximum voltage When the sum of the value and the minimum voltage value is less than zero, the pole voltage is determined to be the difference between the preset value and the minimum voltage value.