Electromagnetic heating control system and air conditioner

Abstract

The invention discloses an electromagnetic heating control system and an air conditioner. The electromagnetic heating control system comprises a voltage acquisition unit; a current acquisition unit; the reference unit is used for providing an expected bus voltage Udc1, an expected bus current idc1 and a total heating time tsum for circularly heating the temperature of a motor to be preheated in the test tool to different target heating temperatures in a three-phase manner under the condition of providing a reference bus voltage, and the processing unit is used for processing the expected bus voltage Udc1, the expected bus current idc1 and the total heating time tsum. The method comprises the following steps: acquiring an expected bus voltage Udc1, an expected bus current idc1 and a total heating time length; determining the single-phase electromagnetic heating time ts = Udc1 / Udc * idc1 / idc * ts1; and controlling the state of a switch tube of the IPM module in the total heating time, and performing three-phase cyclic heating on the motor winding. The equivalent heating requirements under different bus voltages are met, and the electromagnetic heating effect and the working reliability of the motor are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic heating, and in particular, to an electromagnetic heating control system and an air conditioner. Background Art

[0002] In recent years, the demand for air conditioners has been continuously expanding in various places. In particular, air conditioners are used for heating in the low-temperature conditions in winter in the northern regions. In an air-conditioning system, the compressor is like the power device of the air conditioner, and the viscosity of the refrigerating oil in the compressor plays a crucial role in the reliability of the compressor. When the air conditioner is in outdoor low-temperature conditions, since the lubricating oil is miscible with the refrigerant, if the outdoor unit is powered off and left standing for a long time, a large amount of refrigerant will deposit in the compressor crankcase, resulting in a decrease in the lubricating oil concentration, which cannot meet the lubrication requirements of the compressor, the lubrication level is insufficient, which is not conducive to the startup of the air-conditioning system, and the temperature of the motor accessory parts is too low at low temperatures, which will also cause problems with unreliable startup.

[0003] To avoid damage to the compressor, it is necessary to preheat the compressor before starting to ensure that the lubricating oil meets the reliability requirements after the compressor starts.

[0004] Currently, most of the industry adopts the method of auxiliary heating, that is, an electric heating tape is provided inside the compressor or externally on the outer wall of the compressor cylinder block. Before the air-conditioning compressor is started, the oil sump is preheated by the electric heating tape, and the compressor is started after meeting the control conditions. This will increase the overall cost of the machine, with large heat loss, high energy consumption, low heating efficiency, and long preheating cycle.

[0005] There are also existing electromagnetic heating control systems. Within the range of the bus voltage, the heating duration remains the same, which will inevitably lead to different equivalent heating powers: First, the heating power may be insufficient at low bus voltages, resulting in poor heating effect of the compressor and not meeting the startup requirements of the overall machine operation; Second, the heating power may exceed the power threshold at high bus voltages, resulting in the temperature rise of the compressor winding exceeding the tolerance upper limit and seriously damaging the compressor body. Therefore, it is urgent to ensure the heating effect and avoid overheating and damage of the compressor under a wide range of bus voltages. Summary of the Invention

[0006] In view of the problems pointed out in the background art, the present invention provides an electromagnetic heating control system, which realizes adjusting the single-phase heating duration according to different bus voltages and heating requirements under a wide range of bus voltages, meets the equivalent heating requirements under different bus voltages, and ensures the electromagnetic heating effect and the working reliability of the motor.

[0007] To achieve the above-mentioned invention purpose, the present invention adopts the following technical solutions to be realized: In some embodiments of the present application, an electromagnetic heating control system is provided. The electromagnetic heating control system is applied to a variable-frequency topology circuit structure. The variable-frequency topology circuit structure includes a rectification unit and an IPM module connected to the output end of the rectification unit. The IPM module inversely converts the bus voltage into alternating current power for driving a motor. The electromagnetic heating control system includes: A voltage acquisition unit for real-time acquisition of the bus voltage Udc; A current acquisition unit for real-time acquisition of the bus current idc; A reference unit for providing, under a reference bus voltage, the desired bus voltage Udc1, the desired bus current idc1, and the total heating duration tsum for heating the temperature of the motor to be preheated in the test tooling to different target heating temperatures in a three-phase cycle. Among them, the single-phase heating duration in the three-phase cycle is preset as ts1; A processing unit configured to perform the following: According to the target heating temperature, obtain the desired bus voltage Udc1, the desired bus current idc1, and the total heating duration required to heat to the target heating temperature; Determine the single-phase electromagnetic heating duration ts = Udc1 / Udc * idc1 / idc * ts1; Within the total heating duration, control the state of the switching tubes of the IPM module to heat the motor windings in a three-phase cycle.

[0008] The technical solutions involved in the above embodiments have the following advantages or beneficial effects: Utilize the test tooling to obtain data (including the desired bus voltage, the desired bus current, and the total heating duration at the target heating temperature) as a reference benchmark during actual electromagnetic heating, improving the reliability of actual heating.

[0009] And during the actual electromagnetic heating process, based on the conservation of electromagnetic heating power, the processing unit adjusts the single-phase heating duration according to the real-time acquired bus voltage and bus current, ensuring equivalent heating effects under different bus voltages, and avoiding the problem of uneven heating effects caused by using a fixed heating duration for a wide bus voltage in the prior art.

[0010] In some embodiments of the present application, the processing unit controls the motor current using a hysteresis control method.

[0011] The technical solutions involved in the above embodiments have the following advantages or beneficial effects: Using the hysteresis control method to control the motor current allows for dynamically adjusting the motor current within the current hysteresis range to control within the set range of the single-phase heating current, ensuring the safety and reliability of single-phase winding heating while avoiding frequent adjustment of the motor current.

[0012] In some embodiments of the present application, when the IPM module is within its temperature safety threshold range, the processing unit controls and adjusts the electromagnetic heating control frequency according to its power loss and / or temperature rise.

[0013] The technical solutions involved in the above embodiments have the following advantages or beneficial effects: The electromagnetic heating control frequency is related to the power loss and / or temperature rise of the IPM module, as well as the current control accuracy. The higher the electromagnetic heating control frequency, the higher the current control accuracy. A larger power loss and higher temperature rise of the IPM module will affect the safety and reliability.

[0014] Considering the working safety and reliability of the IPM module, within the range of ensuring its temperature safety threshold, the electromagnetic heating control frequency is controlled and adjusted according to the power loss and / or temperature rise, thereby adjusting the current control accuracy.

[0015] In some embodiments of the present application, the processing unit obtains the power loss and / or temperature rise of the IPM module according to the bus voltage and bus current collected in real time.

[0016] The technical solutions involved in the above embodiments have the following advantages or beneficial effects: The bus voltage and bus current are related to the power loss and / or temperature rise of the IPM module. Therefore, based on the bus voltage and bus current collected in real time, the power loss and / or temperature rise can be obtained, which is intuitive and reliable.

[0017] In some embodiments of the present application, the control and adjustment of the electromagnetic heating control frequency are specifically as follows: When the power loss and / or temperature rise of the IPM module reaches the upper limit value of the power loss and / or temperature rise threshold, the electromagnetic heating control frequency is controlled to decrease. Among them, the greater the power loss and / or temperature rise, the lower the electromagnetic heating control frequency, and the electromagnetic heating control frequency is lower than the preset control frequency; When the power loss and / or temperature rise of the IPM module reaches the lower limit value of the power loss and / or temperature rise threshold, the electromagnetic heating control frequency is controlled to be the preset control frequency.

[0018] The technical solutions involved in the above embodiments have the following advantages or beneficial effects: The higher the electromagnetic heating control frequency, the higher the current control accuracy. Therefore, on the premise of ensuring the working reliability of the IPM module, ensuring a high electromagnetic heating control frequency can improve the current control accuracy.

[0019] When the power loss of the IPM module is greater and the temperature rise is higher, it will affect the safety and reliability of the IPM module. Therefore, at this time, the electromagnetic heating control frequency needs to be decreased to control and reduce the power loss and temperature rise of the IPM module.

[0020] In some embodiments of the present application, the voltage acquisition unit is a voltage dividing circuit, and the input power supply of the voltage dividing circuit is the input voltage of the rectifying unit; The current acquisition unit is a sampling resistor, which is connected in series in the power supply loop of the rectifying unit.

[0021] The technical solutions involved in the above embodiments have the following advantages or beneficial effects: The voltage dividing circuit and the sampling resistor are used to obtain the bus voltage and the bus current in real time, which is convenient for obtaining the single-phase heating duration under different bus voltages in real time.

[0022] Some embodiments of the present application further relate to an air conditioner, including: A refrigerant circulation loop for circulating the refrigerant in a compressor, a condenser, an expansion valve, and an evaporator; A compressor, which is driven by a motor and is used to compress the low-temperature and low-pressure refrigerant gas into a high-temperature and high-pressure refrigerant gas and discharge it to the condenser. The AC power generated by the conversion of the variable-frequency topology circuit structure is used to drive the motor; The air conditioner further includes: The electromagnetic heating control system as described above, which is used to drive the state of the switching tubes of the IPM module in the variable-frequency topology circuit structure by the processing unit during the preheating stage for electromagnetic heating of the motor.

[0023] The technical solutions involved in the above embodiments have the following advantages or beneficial effects: Using the test tooling to obtain data (including the expected bus voltage, the expected bus current, and the total heating duration at the target heating temperature) as the reference benchmark during actual electromagnetic heating improves the reliability of actual heating.

[0024] And during the actual electromagnetic heating process, the processing unit adjusts the single-phase heating duration based on the electromagnetic heating power conservation according to the bus voltage and the bus current obtained in real time, ensuring that the heating effects of the compressor are equivalent under different bus voltages and avoiding poor heating effects and overheating damage of the compressor.

[0025] In some embodiments of the present application, the air conditioner further includes: An ambient temperature sensor, which is used to detect the ambient temperature where the compressor is located. When the ambient temperature reaches below the preset temperature threshold, it controls the air conditioner to enter the preheating stage.

[0026] The technical solutions involved in the above embodiments have the following advantages or beneficial effects: When the ambient temperature is low, the air conditioner enters the preheating stage and uses electromagnetic heating to preheat the compressor.

[0027] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become clearer. Description of the Drawings

[0028] 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 accompanying drawings required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0029] Figure 1 is a schematic block diagram of the principle of an existing air conditioner; Figure 2 is a circuit diagram of an existing variable-frequency topology circuit structure; Figure 3 is a circuit diagram of the variable-frequency topology circuit structure involved in the embodiments of the present invention; Figure 4 is a schematic diagram of the DC bias current path in the variable-frequency topology circuit structure when adjusting the duty cycle of the V-phase PWM according to the embodiment; Figure 5 is a schematic diagram of the DC bias current path in the variable-frequency topology circuit structure when adjusting the duty cycles of the V-phase PWM and the W-phase PWM respectively according to the embodiment; Figure 6 is a schematic block diagram of the principle of the electromagnetic heating control system according to the embodiment; Figure 7 is a flowchart of the three-phase cyclic heating of the electromagnetic heating control system according to the embodiment; Figure 8 is a flowchart of controlling and adjusting the electromagnetic heating control frequency in the electromagnetic heating control system according to the embodiment; Figure 9 is a schematic block diagram of the preheating control of the air conditioner according to the embodiment; Figure 10 is a flowchart of the preheating control of the air conditioner according to the embodiment; 100. Variable-frequency topology circuit structure; 110. Rectification unit; 120. PFC circuit; 130. IPM module; 200. Voltage acquisition unit; 300. Current acquisition unit; 400. Processing unit; 500. Reference unit; 600. Motor; 700. Compressor; 800. Ambient temperature sensor. Detailed Embodiments

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without making creative efforts shall fall within the protection scope of the present application.

[0031] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0032] The terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise stated, the meaning of "plurality" is two or more.

[0033] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0034] In the present invention, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "below" and "beneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0035] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0036] A variable-frequency topology circuit structure is used to perform variable-frequency control on a motor (such as a permanent magnet synchronous motor, an AC motor).

[0037] The motor used in the compressor of an air conditioner is generally an AC motor. Therefore, the variable-frequency topology circuit structure is widely used in air conditioners to variably adjust the frequency of the motor used in the compressor of the air conditioner.

[0038] An air conditioner of an air conditioner performs a refrigeration cycle of the air conditioner 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 to cool or heat an indoor space.

[0039] A low-temperature and low-pressure refrigerant enters the compressor, and the compressor compresses it into 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.

[0040] The expansion valve expands the high-temperature and high-pressure liquid-phase refrigerant formed by condensation 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 can achieve a refrigeration effect by using the latent heat of evaporation of the refrigerant to exchange heat with the material to be cooled. Throughout the cycle, the air conditioner can adjust the temperature of the indoor space.

[0041] See Figure 1 , the outdoor unit of the air conditioner refers to the part of the refrigeration cycle including the compressor and the outdoor heat exchanger. The indoor unit of the air conditioner includes the indoor heat exchanger, and the expansion valve can be provided in the indoor unit or the outdoor unit.

[0042] The indoor heat exchanger and the outdoor heat exchanger are used as condensers or evaporators. When the indoor heat exchanger is used as a condenser, the air conditioner serves as a heater in the heating mode. When the indoor heat exchanger is used as an evaporator, the air conditioner serves as a cooler in the cooling mode.

[0043] The outdoor unit of the air conditioner is also commonly referred to as the outdoor air conditioner unit, and the indoor unit of the air conditioner is also commonly referred to as the indoor air conditioner unit.

[0044] See Figure 2 , which shows the existing variable-frequency topology circuit structure.

[0045] In some embodiments of the present application, the variable-frequency topology circuit structure includes a rectification unit 110 and an IPM module (Intelligent Power Module) 130.

[0046] The input end of the rectification unit 110 is connected to the three-phase AC power supply AC. The rectification unit 110 is used to rectify the alternating current provided by the AC power supply AC to obtain the rectified direct current (i.e., the bus voltage Udc).

[0047] The rectification unit 110 can be a three-phase rectifier bridge, which is formed by connecting six rectifier diodes.

[0048] The IPM module 130 receives the rectified direct current and inversely converts it into three-phase alternating current for use by the AC motor 600.

[0049] The IPM module 130 is a three-phase power inverter, which is used to drive the AC motor 600 after inverting the direct current.

[0050] The three-phase power inverter is composed of six switching tubes, namely, the switching tube T1 on the upper arm of the U phase, the switching tube T3 on the upper arm of the V phase, the switching tube T5 on the upper arm of the W phase, the switching tube T2 on the lower arm of the U phase, the switching tube T4 on the lower arm of the V phase, and the switching tube T6 on the lower arm of the W phase.

[0051] In some embodiments of the present application, for power factor correction of the power supply, see Figure 1 , the existing variable-frequency topology circuit structure further includes a PFC circuit 120, and the PFC circuit 120 is connected between the output end of the rectification unit 110 and the electrolytic capacitor E1.

[0052] Both the rectification unit 110 and the electrolytic capacitor E1 are used in cooperation with the PFC circuit 120.

[0053] The PFC circuit 120 can perform boost processing on the rectified direct current while performing power factor correction on the power supply to provide a stable DC bus voltage for the electrolytic capacitor E1.

[0054] The structure of the PFC circuit 120 is a conventional existing technology. For example, a BOOST topology structure can be adopted, and details are not described herein.

[0055] The above variable-frequency topology circuit structure is only shown as an example, and the variable-frequency topology circuit structure involved in the present application is not limited to the above.

[0056] The variable-frequency topology circuit structure is mostly used in the outdoor unit of an air conditioner. The mainstream control algorithm for the motor used in the compressor 700 in the outdoor unit of the air conditioner is field-oriented control (FOC), also known as vector control.

[0057] FOC control is a conventional technical means in motor control and will not be elaborated here.

[0058] The present application is concerned with the preheating control before the motor starts with FOC control.

[0059] In some embodiments of the present application, referring to Figure 3 , the DC bus voltage Udc can be collected by the voltage acquisition unit 200.

[0060] The voltage acquisition unit 200 may include a voltage division circuit connected between the positive and negative poles of the bus DC power supply Udc. The voltage division circuit includes resistors R3 and R4 connected in series.

[0061] In some embodiments of the present application, referring to Figure 3 , the DC bus current idc is collected by the current acquisition unit 300.

[0062] The current acquisition unit 300 can be implemented by selecting a sampling resistor R1. One end of the sampling resistor R1 is connected to the common connection point of the three lower bridge arms of the IPM module 130, and the other end is connected to the negative terminal of the bus DC power supply Udc.

[0063] In some embodiments of the present application, an electromagnetic heating control system is used to perform electromagnetic heating control on the motor 600 before the motor starts, so as to preheat the motor 600 at a low ambient temperature and improve the reliable start of the motor at a low ambient temperature.

[0064] In some embodiments of the present application, the process of preheating the motor winding by the electromagnetic heating control system is carried out in a three-phase cyclic heating mode to avoid thermal stress on the switching tubes on the IPM module 130 in the electromagnetic heating control system.

[0065] In some embodiments of the present application, the single-phase heating mode can be: the motor current flows through one-phase winding and flows out from the other two parallel windings to form an AC current loop. For example, the motor current flows through the U-phase winding and flows out from the parallel V-phase and W-phase windings to form an AC current loop.

[0066] The three-phase cyclic heating method can be: cyclically switching the windings through which the motor current flows. For example, first, it flows through the U-phase winding and converges from the parallel V-phase and W-phase windings to form an AC current loop, then it flows through the V-phase winding and converges from the parallel W-phase and U-phase windings to form an AC current loop, and then it flows through the W-phase winding and converges from the parallel U-phase and V-phase windings to form an AC current loop.

[0067] In some embodiments of the present application, in order to improve the electromagnetic heating effect, a DC bias current can be superimposed on the three-phase alternating current.

[0068] In some embodiments of the present application, by adjusting the angle by which the rising edge of the high level of a certain phase of PWM is shifted backward, the pulse width of the duty cycle of this phase of PWM is adjusted, so that the duty cycle of this phase of PWM is different from the duty cycles of the other two phases of PWM, and a bias voltage is generated between the three-phase motor voltages, generating a DC bias current.

[0069] See Figure 4 , the flow path of the total DC bias current (indicated by the arrow), first passes through the switching tube T3 of the upper bridge arm of the V phase, and flows into the switching tubes T2 of the lower bridge arm of the U phase and T6 of the lower bridge arm of the W phase respectively, and then flows out.

[0070] The three-phase cyclic heating method is to cyclically switch the phase sequence of the three-phase PWM for pulse width adjustment. For example, the pulse width of the U-phase PWM can be adjusted first, then switched to the pulse width adjustment of the V-phase PWM, and then switched to the pulse width adjustment of the V-phase PWM.

[0071] In some embodiments of the present application, the duty cycles of two of the three-phase PWM can also be adjusted to be different from the duty cycle of the remaining one phase of PWM, so that the phases of the two of the three-phase PWM are 120 degrees out of phase with each other, one phase of the two of the three-phase PWM is more than 120 degrees out of phase with the remaining one phase of PWM, and the other phase of the two of the three-phase PWM is less than 120 degrees out of phase with the remaining one phase of PWM, so that a bias voltage is also generated between the three-phase motor voltages, and thus a DC bias current is generated.

[0072] See Figure 5 , the flow path of the total DC bias current (indicated by the arrow), the DC bias current flows out in parallel through the switching tube T3 of the upper bridge arm of the V phase and the switching tube T5 of the upper bridge arm of the W phase, and flows into the switching tube T2 of the lower bridge arm of the U phase, and then flows out.

[0073] The three-phase cyclic heating method is to cyclically switch the combined phase sequence of two adjacent phases in the three-phase PWM for duty cycle adjustment. For example, the duty cycles of the U-phase PWM and the V-phase PWM can be adjusted first, then switched to the duty cycle adjustment of the V-phase PWM and the W-phase PWM, and then switched to the duty cycle adjustment of the V-phase PWM and the U-phase PWM.

[0074] In some embodiments of the present application, in order to achieve the purpose of equivalent heating power under a wide range of bus voltages, before actually heating the motor winding, a test tooling is built to obtain equivalent reference data.

[0075] The test tooling is a test motor as a reference, and all the hardware circuits required for this test motor are needed, such as the variable-frequency topology circuit structure, temperature acquisition unit, bus voltage acquisition unit, and bus current acquisition unit for this test motor.

[0076] In some embodiments of the present application, in order to achieve electromagnetic heating control of the motor winding, a temperature acquisition unit (not shown) is used to acquire the motor temperature td, and the motor temperature td can be a temperature characterizing the temperature change of the motor winding and is used to measure the heating condition of the motor winding.

[0077] In some embodiments of the present application, based on the test tooling, the motor winding current isth and the single-phase heating duration ts1 are set, and the DC bus voltage and DC bus current (respectively used as the desired bus voltage Udc1 and desired bus current idc1 at this target heating temperature) for heating the motor temperature td to the desired target heating temperature (such as 20 °C) are tested at the reference bus voltage (such as 600 V), and the total heating duration tsum is recorded at this time.

[0078] In this way, at different target heating temperatures, different desired bus voltages Udc1, desired bus currents idc1, and total heating durations tsum are obtained.

[0079] These data are used as reference data to equivalent the power during actual electromagnetic heating of the motor winding, ensuring that the electromagnetic heating power is equivalent under different actual bus voltages and improving the heating uniformity.

[0080] In some embodiments of the present application, refer to Figure 6 , the electromagnetic heating control system includes a reference unit 500, which is used to provide these reference data.

[0081] In some embodiments of the present application, refer to Figure 6 , the electromagnetic heating control system further includes a voltage acquisition unit 200, which is used to acquire the bus voltage Udc in real time, and a voltage division circuit as described above can be used.

[0082] In some embodiments of the present application, refer to Figure 6 , the electromagnetic heating control system further includes a current acquisition unit 300, which is used to acquire the bus current idc in real time, and a sampling resistor R1 as described above can be used.

[0083] In some embodiments of the present application, in order to achieve equivalent electromagnetic heating power, refer toFigure 7 The processing unit 400 can perform the following operations: (1) determine the expected bus voltage, expected bus current, and total heating duration corresponding to the target heating temperature based on the determined target heating temperature to be preheated and the reference data provided by the reference unit 500; (2) determine the single-phase electromagnetic heating duration based on the principle of electromagnetic power conservation, where different bus voltages have different single-phase electromagnetic heating durations; (3) control the IPM module 130 to achieve three-phase cyclic heating.

[0084] In some embodiments of the present application, referring to Figure 7 the reference data provided by the reference unit 500 according to the currently required target heating temperature T, and obtain the expected bus voltage Udc1, expected bus current idc1, and total heating duration tsum corresponding to the target heating temperature T.

[0085] For the test fixture, when heating in a single phase, the expected average power is P1 平均 : P1 平均 = W1 / ts1 = P1*ts1 / ts1 = Udc1*idc1*ts1 / ts1.

[0086] In some embodiments of the present application, if the input current bus voltage is Udc, the bus current idc is obtained in real time, and the current electromagnetic heating power P is obtained in real time using P = Udc*idc.

[0087] In some embodiments of the present application, to ensure that the heating power is not affected by the bus voltage fluctuation, using the reference data as a reference to ensure that the average power is equal under single-phase heating, so Udc1*idc1*ts1 / ts1 = Udc*idc*ts / ts1.

[0088] Using the above formula, obtain ts = Udc1 / Udc*idc1 / idc*ts1, where ts is the single-phase heating duration corresponding to the current bus voltage.

[0089] In this way, for different bus voltages within a wide bus voltage range, the single-phase heating duration is also different, thus ensuring that the heating effects are equivalent under different bus voltages.

[0090] In some embodiments of the present application, during the actual heating process, a single-phase heating current is set. According to the obtained single-phase heating duration ts and total heating duration tsum, within the total heating duration tsum, the states of the switching tubes of the IPM module 130 are controlled to perform three-phase cyclic heating on the motor windings.

[0091] In some embodiments of the present application, according to tests or experience, the single-phase heating current can be set to a preset value or a preset range.

[0092] In some embodiments of the present application, within the wide range of bus voltages from 457V to 820V, at different bus voltages, the single-phase heating duration is different. That is, when the bus voltage is high, the single-phase heating duration is short, and when the bus voltage is low, the single-phase heating duration is long, avoiding the problem that a high heating power is generated under a high bus voltage, resulting in the motor winding temperature rise exceeding the tolerance upper limit, or the heating power is insufficient under a low bus voltage, resulting in poor heating effect of the motor winding.

[0093] In this way, it is ensured that the single-phase electromagnetic heating is equivalent under a wide range of bus voltages, the heating effect is guaranteed, and the motor winding is prevented from overheating and being damaged.

[0094] In some embodiments of the present application, during the actual electromagnetic heating process, in order to avoid frequent adjustment of the motor current is, for the motor current is, a hysteresis control is introduced, and through dynamic adjustment, the motor current is is controlled within the range of the single-phase heating current.

[0095] In some embodiments of the present application, during the actual heating process, the electromagnetic heating control frequency f of the motor 600 is related to the current control accuracy. The higher the electromagnetic heating control frequency f, the higher the current control accuracy, but the power loss and temperature rise of the IPM module 130 will also continuously increase, seriously affecting its working safety and reliability.

[0096] Therefore, taking into account both the current control accuracy and the working safety and reliability of the IPM module 130, within the temperature safety threshold range of the IPM module 130, the electromagnetic heating control frequency is controlled and adjusted according to the power loss and / or temperature rise of the IPM module 130.

[0097] In some embodiments of the present application, the temperature safety threshold range, the power loss and / or temperature rise threshold, and the preset control frequency of the motor 600 can be set according to tests or experience.

[0098] The preset control frequency can consider factors such as current control accuracy, noise, and the heat dissipation performance of the IPM module 130.

[0099] In some embodiments of the present application, the preset control frequency fth can be a preset value; the power loss and / or temperature rise threshold can be a preset value or a preset range.

[0100] In some embodiments of the present application, the processing unit 400 can calculate the power loss and / or temperature rise P of the IPM module 130 in real time according to the real-time collected bus voltage and bus current. For example, the processing unit 400 will give a fitting curve of the power loss and / or temperature rise of the IPM module 130 according to the collected bus voltage and bus current, and the power loss and / or temperature rise are positively correlated.

[0101] Therefore, based on the bus voltage and bus current collected in real time, the power loss and / or temperature rise P of the IPM module 130 can be obtained.

[0102] In some embodiments of the present application, within the temperature safety threshold range of the IPM module 130, the electromagnetic heating control frequency is increased as much as possible (but lower than the electromagnetic heating control frequency limit), and at the same time, the working reliability of the IPM module 130 should also be considered.

[0103] See Figure 8 , which gives a flowchart for controlling and adjusting the electromagnetic heating control frequency.

[0104] When it is obtained in real time that the power loss and / or temperature rise P reaches the upper limit value of the power loss and / or temperature rise threshold, the electromagnetic heating control frequency is reduced, where the greater the power loss and / or temperature rise, the lower the electromagnetic heating control frequency.

[0105] When it is obtained in real time that the power loss and / or temperature rise P reaches the lower limit value of the power loss and / or temperature rise threshold, the electromagnetic heating control frequency is controlled to be the preset control frequency fth to ensure current control accuracy.

[0106] For the convenience of description, in some embodiments of the present application, the power loss and / or temperature rise limit is set to Pth.

[0107] That is, see Figure 8 , when P > Pth, the electromagnetic heating control frequency is reduced, and when P ≤ Pth, the electromagnetic heating control frequency is the preset control frequency fth.

[0108] Although the above describes two cases under P > Pth and P ≤ Pth, it can also be the following situation: when P ≥ Pth, the electromagnetic heating control frequency is reduced, and when P < Pth, the electromagnetic heating control frequency is the preset control frequency fth.

[0109] In some embodiments of the present application, the following formula can be used to specifically obtain the reduced electromagnetic heating control frequency f.

[0110] When P > Pth, f = fth – (P – Pth) / Pth * fth; when P ≤ Pth, f = fth.

[0111] In this way, while ensuring high current control accuracy, according to different bus voltages and heating requirements, the single-phase heating duration is adjusted to meet the equivalent heating requirements under different bus voltages, ensuring the electromagnetic heating effect and the working reliability of the motor.

[0112] The present application also relates to an air conditioner, which uses the electromagnetic heating control system described above for preheating, and after the preheating is completed, the compressor 700 starts normally.

[0113] The air conditioner described above includes a refrigerant circulation circuit (not shown), a compressor 700, an outdoor heat exchanger (not shown), an indoor heat exchanger (not shown), a four-way valve (not shown), and the electromagnetic heating control system described above.

[0114] The refrigerant circulation circuit circulates refrigerant among the compressor 700, a condenser, an expansion valve, and an evaporator.

[0115] One of the outdoor heat exchanger and the indoor heat exchanger operates as a condenser, and the other operates as an evaporator.

[0116] The four-way valve is used to control the flow direction of the refrigerant in the refrigerant circulation circuit, so as to switch between the outdoor heat exchanger and the indoor heat exchanger as a condenser and an evaporator.

[0117] The compressor 700 is driven by an electric motor and is used to compress the low-temperature and low-pressure refrigerant gas into a high-temperature and high-pressure refrigerant gas and discharge it to the condenser.

[0118] For example, the heating cycle of the air conditioner will be described as an example.

[0119] When the four-way valve is powered on, the compressor 700 compresses the low-temperature and low-pressure refrigerant into a high-temperature and high-pressure state, and the refrigerant discharged from the compressor 700 passes through the gas-side stop valve and the pipe and enters the indoor heat exchanger through the four-way valve.

[0120] After heat exchange inside the indoor heat exchanger, it condenses and releases heat, becoming a liquid refrigerant. Subsequently, the refrigerant passes through the indoor-side throttling device, the pipe, and the liquid-side stop valve, enters the throttling device and is throttled to a low-temperature and low-pressure gas-liquid two-phase state. The two-phase refrigerant enters the outdoor heat exchanger to evaporate and absorb heat, becoming a gas state.

[0121] The refrigerant coming out of the outdoor heat exchanger enters the gas-liquid separator through the four-way valve and is finally sucked into the compressor 700 for compression, completing the heating cycle.

[0122] In the above heating cycle, the indoor heat exchanger is used as a condenser, and the outdoor heat exchanger is used as an evaporator.

[0123] The AC power generated by the conversion of the variable-frequency topology circuit structure is used to drive the electric motor of the compressor 700, an AC motor.

[0124] In some embodiments of the present application, the total heating duration can be referred to as the preheating stage.

[0125] When the air conditioner needs to be preheated, the air conditioner enters the preheating stage and uses the electromagnetic heating control system described above for preheating. When the total heating duration is reached, the preheating stage is completed.

[0126] After the preheating stage is completed, the compressor 700 is normally started by using the conventional FOC control method.

[0127] See Figure 9 , a room temperature sensor 800 can be set to detect the ambient temperature where the compressor is located.

[0128] See Figure 10 , which shows the flowchart of the preheating control of the air conditioner.

[0129] When the ambient temperature reaches below the preset temperature threshold, it is considered that the outdoor unit of the air conditioner is in the low ambient temperature working condition.

[0130] In the low ambient temperature working condition, the compressor 700 needs to be preheated before starting to ensure reliable startup of the compressor 700. Otherwise, there is no need to preheat the compressor 700.

[0131] In some embodiments of the present application, when obtaining the reference data, the motor temperature td collected by the temperature acquisition unit is the temperature at the exhaust pipe of the compressor 700, which can accurately represent the preheating situation of the compressor 700.

[0132] In the description of the above embodiments, the specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0133] The above are only the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An electromagnetic heating control system, characterized in that, The electromagnetic heating control system is applied to a variable-frequency topology circuit structure. The variable-frequency topology circuit structure includes a rectification unit and an IPM module connected to the output end of the rectification unit. The IPM module inversely transforms the bus voltage into alternating current power for driving a motor. The electromagnetic heating control system includes: A voltage acquisition unit for real-time acquisition of the bus voltage Udc; A current acquisition unit for real-time acquisition of the bus current idc; A reference unit for providing, under a reference bus voltage, the desired bus voltage Udc1, the desired bus current idc1, and the total heating duration tsum for heating the temperature of the motor to be preheated in the test tooling to different target heating temperatures in a three-phase cycle. Among them, the single-phase heating duration in the three-phase cycle is preset to ts1; A processing unit configured to perform the following: According to the target heating temperature, obtain the desired bus voltage Udc1, the desired bus current idc1, and the total heating duration required to heat to the target heating temperature; Determine the single-phase electromagnetic heating duration ts = Udc1 / Udc * idc1 / idc * ts1; Within the total heating duration, control the states of the switching tubes of the IPM module to heat the three phases of the motor winding in a cycle.

2. The electromagnetic heating control system according to claim 1, wherein: The processing unit controls the motor current in a hysteresis control manner.

3. The electromagnetic heating control system according to claim 1, wherein: When the IPM module is within its temperature safety threshold range, the processing unit controls and adjusts the electromagnetic heating control frequency according to its power loss and / or temperature rise.

4. The electromagnetic heating control system according to claim 3, characterized in that, The processing unit obtains the power loss and / or temperature rise of the IPM module according to the real-time acquired bus voltage and bus current.

5. The electromagnetic heating control system according to claim 3, wherein Controlling and adjusting the electromagnetic heating control frequency specifically includes: When the power loss and / or temperature rise of the IPM module reaches the upper limit value of the power loss and / or temperature rise threshold, control to reduce the electromagnetic heating control frequency. Among them, the greater the power loss and / or temperature rise, the lower the electromagnetic heating control frequency, and the electromagnetic heating control frequency is lower than the preset control frequency; When the power loss and / or temperature rise of the IPM module reaches the lower limit value of the power loss and / or temperature rise threshold, control the electromagnetic heating control frequency to be the preset control frequency.

6. The electromagnetic heating control system according to claim 1, wherein: The voltage acquisition unit is a voltage division circuit, and the input power supply of the voltage division circuit is the input voltage of the rectification unit; The current acquisition unit is a sampling resistor, which is connected in series in the power supply circuit of the rectification unit.

7. An air conditioner, characterized in that, Including: A refrigerant circulation loop for circulating the refrigerant in a compressor, a condenser, an expansion valve, and an evaporator; A compressor driven by a motor for compressing low-temperature and low-pressure refrigerant gas into high-temperature and high-pressure refrigerant gas and discharging it to the condenser. The alternating current power generated by the conversion of the variable-frequency topology circuit structure is used to drive the motor; It is characterized in that the air conditioner further includes: The electromagnetic heating control system according to any one of claims 1 to 6 is used to drive the state of the switching tubes of the IPM module in the variable-frequency topology circuit structure during the preheating stage, so as to perform electromagnetic heating on the motor.

8. The air conditioner according to claim 7, characterized in that, The air conditioner further includes: a ambient temperature sensor, which is used to detect the ambient temperature where the compressor is located, and when the ambient temperature reaches below a preset temperature threshold, controls the air conditioner to enter the preheating stage.

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