CN118564425A

CN118564425A - Compressor, air conditioning device, and heating method

Info

Publication number: CN118564425A
Application number: CN202311783642.9A
Authority: CN
Inventors: 河村建吾; 小仓洋寿; 尾花紫织; 森川智贵
Original assignee: Hitachi Johnson Controls Air Conditioning Inc
Current assignee: Hitachi Johnson Controls Air Conditioning Inc
Priority date: 2023-02-28
Filing date: 2023-12-22
Publication date: 2024-08-30
Also published as: JP7412618B1; JP2024121966A

Abstract

The invention provides a compressor, an air conditioning apparatus and a heating method, which can obtain expected heating effect regardless of the position of a magnet when the compressor is stopped. A compressor (21) comprises: a motor (30) provided with a plurality of coils and magnets; a rotation shaft which is rotated by a motor (30); a compression mechanism that compresses a fluid by rotation of the rotation shaft; lubricating oil which is supplied to a sliding part of the compressor (21) through the inside of the rotating shaft; and a control unit (50) that generates a rectangular wave signal for passing a current through the coil of the motor (30). A control unit (50) generates rectangular wave signals for predetermined coils so that the positional relationship between the plurality of coils and the permanent magnets becomes a predetermined positional relationship, and generates rectangular wave signals for the coils in order to heat the lubricating oil via the rotating shaft after the position of the permanent magnets is adjusted.

Description

Compressor, air conditioning device, and heating method

Technical Field

The present invention relates to a compressor, an air conditioning apparatus, and a method for heating lubricating oil.

Background

The compressor for an air conditioner uses a refrigerant as a fluid, and a lubricating oil is mixed with the refrigerant in a system to lubricate each place in the system and return the lubricating oil to the compressor. When the outside air temperature decreases during the stop of the operation of the air conditioner, the refrigerant condenses, and the liquid refrigerant is heavier than the lubricating oil, so that the liquid refrigerant accumulates in the bottom portion to form a linear layer.

When the compressor is started in such a state, the refrigerant in the lubricant oil that has become low in pressure due to the suction of the refrigerant rapidly boils, the lubricant oil bubbles, the lubricant oil is discharged to the outside of the compressor together with the refrigerant, and the oil surface of the lubricant oil is lowered (oil foaming). As a result, the oil supply to the sliding portion becomes insufficient, and lubrication failure occurs. In order to prevent the occurrence of such lubrication failure, the lubricating oil is heated by using a heater or by using an electromagnetic induction heating principle.

The system using the electromagnetic induction heating principle is inexpensive compared with the system using a heater, but in order to achieve desired heating by the characteristics of a permanent magnet and a motor winding, it is necessary to flow a high-frequency alternating current to the extent that the motor cannot follow as a rotating motion through the motor winding (coil), and to adjust the amount of current.

The amount of current can be adjusted by changing the ratio of the time (DUTY: DUTY) at which the current is on in one period of the PWM (Pulse Width Modulation ) signal. When the period of the PWM signal is set to a high speed in order to generate an ac current of a high frequency, the switching loss of the inverter element increases, and it is necessary to cope with an increase in cost due to an increase in a heat sink for heat dissipation or the like.

Therefore, in order to reduce switching loss, a technique has been proposed in which an ac current is formed in a simulated manner by using a current delay caused by inductance of a motor winding (for example, refer to patent document 1).

However, in the above-described conventional technique, since the heating effect varies depending on the position of the magnet provided in the motor, there is a problem that the desired heating effect cannot be obtained depending on the position of the magnet when the compressor is stopped.

Patent document 1: chinese patent application publication No. 107218711

Disclosure of Invention

The present invention has been made in view of the above problems, and provides a compressor including: a motor provided with a plurality of windings and a magnet; a rotation shaft rotated by a motor; a compression mechanism that compresses a fluid by rotation of a rotation shaft; a lubricant oil which is supplied to a sliding part of the compressor through the inside of the rotating shaft; and a control unit that generates rectangular wave signals for causing current to flow through windings of the motor, wherein the control unit generates rectangular wave signals for predetermined windings such that positional relationships between the plurality of windings and the magnets are a predetermined positional relationship, and generates rectangular wave signals for the windings in order to heat the lubricating oil via the rotating shaft after the positions of the magnets are adjusted.

According to the present invention, a desired heating effect can be obtained regardless of the position of the magnet when the compressor is stopped.

Drawings

Fig. 1 is a diagram showing a structural example of an air conditioning apparatus according to the present embodiment.

Fig. 2 is a diagram showing a configuration example of a compressor for an air conditioning apparatus.

Fig. 3 is a diagram showing an example of the structure of an outdoor unit using the electromagnetic induction heating principle.

Fig. 4 is a diagram illustrating the PWM signal.

Fig. 5 is a diagram showing a configuration example of a control unit provided in the compressor.

Fig. 6 is a diagram illustrating conventional heating control.

Fig. 7 is a diagram illustrating an outline of the present heating control.

Fig. 8 is a diagram illustrating currents flowing through the phases in the preparatory operation before the heating operation.

Fig. 9 is a diagram illustrating PWM signals during heating operation and currents flowing through the phases.

Fig. 10 is a flowchart showing an example of the flow of the present heating control.

Fig. 11 is a diagram illustrating another example of the current flowing through each phase in the preparatory operation before the heating operation.

Detailed Description

Fig. 1 is a diagram showing a structural example of an air conditioning apparatus according to the present embodiment. The air conditioning apparatus 10 includes an indoor unit 11 installed in a space (indoor) to be air-conditioned and an outdoor unit 20 installed outdoors, and performs air-conditioning by circulating a refrigerant as a fluid between the indoor unit 11 and the outdoor unit 20 and exchanging heat with air in the indoor.

The indoor units 11 and the outdoor units 20 may be each composed of two or more, or two or more indoor units 11 may be connected to one outdoor unit 20. As the refrigerant, a Hydrofluorocarbon (HFC), a Hydrofluoroolefin (HFO), or the like can be used. As HFC, R32 (CH ₂F₂)、R410A(CH₂F₂+C₂HF₃) and the like can be used, and as HFO, R1234yf (CF ₃CF＝CH₂) and the like can be used.

The indoor unit 11 includes an indoor heat exchanger 12, an indoor fan 13, and an indoor fan drive motor 14. The indoor fan 13 is driven by an indoor fan driving motor 14, and takes in indoor air and sends it into the indoor heat exchanger 12. The indoor heat exchanger 12 has a plurality of heat transfer tubes through which the refrigerant flows, and the air fed into the indoor heat exchanger is in contact with the surfaces of the plurality of heat transfer tubes to exchange heat with the refrigerant. The air heat-exchanged by the indoor heat exchanger 12 is sent out to the room.

In addition, the indoor unit 11 may further include various sensors for measuring an indoor temperature and the like, an indoor expansion valve for decompressing and expanding the refrigerant, and the like, and controlling the flow rate of the refrigerant.

The outdoor unit 20 includes a compressor 21, a four-way valve 22, an outdoor expansion valve 23, an outdoor heat exchanger 24, an outdoor fan 25, and an outdoor fan drive motor 26. The compressor 21 includes a receiver 27, and is driven by a compressor driving motor, and sucks low-pressure gas refrigerant from the receiver 27, boosts the pressure, and discharges the boosted pressure gas refrigerant as high-pressure gas refrigerant. The accumulator 27 is a container for preventing liquid from returning to the compressor 21 and separating the liquid at the time of transition, and adjusts the dryness of the refrigerant to be appropriate. The dryness is the proportion of steam in the wet steam representing the mixed state of the steam and the fine droplets.

The four-way valve 22 switches the direction of the refrigerant flow according to the operation state (operation mode) of the air conditioning apparatus 10. The operation modes include a cooling mode, a heating mode, and a blowing mode. The outdoor expansion valve 23 is a valve for decompressing and expanding the high-pressure refrigerant, and is a valve capable of controlling the flow rate of the refrigerant. The outdoor fan 25 is driven by an outdoor fan driving motor 26, sucks in outdoor air, and sends the air to the outdoor heat exchanger 24. The outdoor heat exchanger 24 is also configured to have a plurality of heat transfer tubes through which the refrigerant flows, like the indoor heat exchanger 12, and the air fed into the heat exchanger is in contact with the surfaces of the plurality of heat transfer tubes to exchange heat with the refrigerant. The air heat-exchanged by the outdoor heat exchanger 24 is sent out to the outside.

The outdoor unit 20 further includes a control device 28. The control device 28 is connected to the compressor 21, the four-way valve 22, the outdoor expansion valve 23, the indoor fan drive motor 14, and the outdoor fan drive motor 26, and controls these. The control device 28 controls the rotation speed of the compressor 21, the opening degree of the outdoor expansion valve 23, the rotation speed of the indoor fan driving motor 14, the rotation speed of the outdoor fan driving motor 26, and the like. The control device 28 can perform these controls based on information detected by various sensors.

In the cooling mode, the indoor heat exchanger 12 is used as an evaporator, the outdoor heat exchanger 24 is used as a condenser, and the refrigerant enclosed in the system is circulated in the order of the compressor 21, the four-way valve 22, the outdoor heat exchanger 24, the outdoor expansion valve 23, the indoor heat exchanger 12, the four-way valve 22, the accumulator 27, and the compressor 21. In the heating mode, conversely, the indoor heat exchanger 12 is used as a condenser, the outdoor heat exchanger 24 is used as an evaporator, and the refrigerant enclosed in the system is circulated in the order of the compressor 21, the four-way valve 22, the indoor heat exchanger 12, the outdoor expansion valve 23, the outdoor heat exchanger 24, the four-way valve 22, the accumulator 27, and the compressor 21.

The air conditioning apparatus 10 is exemplified as the apparatus having the compressor 21, but the present invention is not limited thereto, and may be a refrigerator, a cooling unit, or the like. The control device 28 is not limited to the outdoor unit 20, and may be provided by the indoor unit 11, may be provided by both the indoor unit 11 and the outdoor unit 20, and may be provided as a center control panel or the like separately from the indoor unit 11 and the outdoor unit 20.

Fig. 2 is a diagram showing an example of the structure of the compressor 21 used in the air conditioning apparatus 10. The compressor 21 includes: a motor 30 having a plurality of coils and magnets as a motor; a rotation shaft (shaft) 31 rotated by the motor 30; a compression mechanism 32 that compresses a refrigerant by rotation of the shaft 31; a lubricant 33 supplied to a sliding portion of the compressor 21 through the inside of the shaft 31; and a control unit that generates each rectangular wave signal for causing a current to flow in each coil of the motor 30. The compressor 21 houses the motor 30, the shaft 31, the compression mechanism 32, and the lubricant 33 in a sealed container 34.

The motor 30 is a 3-phase motor that operates using 3 alternating currents with changed phases, and includes: a hollow cylindrical stator 30a having 3 coils as a plurality of coils; and a rotor 30b rotatably disposed in the stator 30a and having a permanent magnet as a magnet. The shaft 31 is disposed at the center of the rotor 30b and rotates with the rotation of the rotor 30b. The coils of the three-phase motor are composed of three coils of U-phase, V-phase, and W-phase, and each coil is arranged at a position offset by 120 ° in a cross section centered on the axis 31.

The compressor 21 includes a control unit functioning as a control unit. The control unit may be mounted on the control device 28 or may be a device different from the control device 28. The control unit receives supply of the commercial power supply, converts ac current into dc current, generates a rectangular wave signal, and generates a voltage (pulse wave) to be applied to the motor 30 so as to cause current to flow through each coil of the motor 30 based on the converted dc current and the generated rectangular wave signal.

The rectangular wave signal is a PWM signal that is repeatedly turned on at Hi and turned off at Low, and is composed of two levels, i.e., hi (high) and Low (Low), such as positive arbitrary voltages V _cc and 0V. The PWM signal is a signal controlled in the following manner: when the current is turned on (also referred to as on time), a constant voltage is applied to increase the current flowing through the coil, and when the current is turned off (also referred to as off time), the application of the voltage is stopped to decrease the current flowing through the coil, thereby making the average current constant. The control unit can adjust the amount of current flowing through the coil by changing the duty ratio of the PWM signal.

Since the 3 coils are arranged at positions offset by 120 ° each, the PWM signal is a signal offset by 120 ° in phase, a high voltage is applied to the 1-phase coil in 3 phases at any time to generate an N pole, the remaining 2-phase coils are low in voltage to generate an S pole, and the poles generated by the coils change with the passage of time. When the coils are arranged in a 120 ° staggered manner in the order of the U phase, V phase, and W phase, the coils generating the N pole change in the order of the U phase, V phase, W phase, U phase, and …. The rotor 30b has permanent magnets, and rotates in a fixed direction by attracting each other in the order of the U phase, V phase, W phase, U phase, … of the N pole by the S pole of the permanent magnets.

The container 34 is a hollow container having a circular cross section and a long shape in one direction, and the shaft 31 is disposed at the center of the cross section. The shaft 31 extends from the motor 30 both upward and downward along the longitudinal direction of the container 34, and is connected to a compression mechanism 32 disposed above the motor 30. The shaft 31 is hollow and its lower end is immersed in a lubricating oil 33 stored in the bottom of a container 34 below the compression mechanism 32. By the rotation of the shaft 31, the lubricant 33 is sucked up through the hollow interior, and the lubricant 33 is supplied from the upper end of the shaft 31 or the like to the sliding portion of the compressor 21.

When the compressor 21 is a scroll compressor, the compression mechanism 32 fixes one of the 2 scrolls in which two plate-like members are formed into a scroll shape of the same shape, and causes the other scroll to perform a circular motion, thereby changing the volume of the space divided by the two scrolls to compress the refrigerant. Of the 2 scrolls, the fixed-side scroll is a fixed scroll, and the orbiting-side scroll is an orbiting scroll. The refrigerant is sucked from the suction port 35, compressed by the compression mechanism 32, and discharged from the discharge port 36.

The sliding portion is a portion where the fixed scroll contacts the orbiting scroll, a portion where a bearing rotatably supporting the shaft 31 with respect to the shaft 31 contacts the shaft 31, or the like. Lubricating oil 33 is supplied to the sliding portions to lubricate the sliding portions. The excessive lubricating oil 33 returns to the bottom of the container 34 via a hole or the like provided in the bearing.

Since the lubricating oil 33 is supplied between the fixed scroll and the orbiting scroll, it also functions as a medium for sealing so that the refrigerant does not leak out from the gap between them, and is compatible with the refrigerant, mixed with the refrigerant, circulated in the system (refrigerant circuit), and returned to the compressor 21 again. While the lubricating oil 33 circulates in the system, the members having sliding portions such as the outdoor expansion valve 23 are lubricated and sealed so as to eliminate gaps such as joints of pipes.

The compressor 21 is described as a scroll compressor, but the compressor 21 may be a rotary compressor in which the motor 30, the shaft 31, the compression mechanism 32, and the lubricant 33 are contained in the container 34.

However, if the above-described bubbling of oil occurs, the oil supply to the sliding portion becomes insufficient and lubrication failure occurs, so that it is necessary to heat the lubricating oil 33 by using a heater or by using an electromagnetic induction heating principle.

Therefore, although the heating can be performed using a heater, the heater needs to be provided around the container 34, and the number of components increases, and the cost increases. In contrast, since the heating by the electromagnetic induction heating principle can be performed by the components and the like of the present compressor 21, the heating can be provided at a lower cost than the heating by the heater. Therefore, a way of utilizing the principle of electromagnetic induction heating is desired.

Here, the principle of electromagnetic induction heating will be briefly described. When a high-frequency alternating current flows through the coil, magnetic lines of force are generated around the coil. When the energized metal is disposed in the vicinity of the magnetic lines of force generated, the eddy current flows in the metal in a direction that impedes the change in magnetic flux. Since the metal has an electric resistance, joule heat is generated due to eddy current flowing through the electric resistance, and the metal is heated.

Referring to fig. 3, a configuration example of the outdoor unit 20 using the electromagnetic induction heating principle will be described. The outdoor unit 20 includes a compressor 21 and a control device 28. The outdoor unit 20 further includes an outdoor heat exchanger 24 and the like, but the outdoor heat exchanger 24 and the like are omitted here. The control device 28 includes an ODU (Out Door Unit) 40 as an example of an information processing Unit and an INV (Inverter) 41 as an example of a conversion Unit. The commercial power supply 42 supplies ac power to the ODU40 and the INV 41.

The ODU40 receives and starts supply of ac power from the commercial power supply 42, generates a PWM signal, and outputs the PWM signal to the INV41 via the transmission line 43. The INV41 generates a pulse wave to be applied to the motor 30 of the Compressor (CMP) 21 based on the ac power from the commercial power source 42 and the PWM signal output from the ODU 40.

The motor 30 includes coils 44 to 46 of U-phase, V-phase, and W-phase. The pulse wave generated by the INV41 is applied to each phase of the motor 30, and when current flows to the coils 44 to 46 of each phase, magnetic force lines are generated as described above, eddy current is generated in the rotor 30b made of a metal material located in the vicinity of the magnetic force lines, joule heat is generated, and the rotor 30b is heated.

The heat of the rotor 30b propagates to the shaft 31, which is also made of a metal material and is in contact with the rotor 30b, and propagates from the shaft 31 to the lubricating oil 33, thereby heating the lubricating oil 33. The warming of the lubricating oil 33 reduces the liquid refrigerant condensed to the bottom of the lubricating oil 33, suppressing the occurrence of oil foaming.

Fig. 4 is a diagram illustrating the PWM signal. In fig. 4, vu represents a desired voltage waveform applied to the U-phase, vv represents a desired voltage waveform applied to the V-phase, and Vw represents a desired voltage waveform applied to the W-phase. These desired voltage waveforms are voltage waveforms to be given to have a predetermined duty ratio. Vc represents a voltage waveform of a carrier wave which is a triangular wave.

In fig. 4, voltages of Vu, vv, vw are compared with voltages of Vc, and when voltages of Vu, vv, vw are higher than voltages of Vc, hi (high) of u+, v+, w+ is indicated, and when voltages of V, V-, W-are lower than voltages of Vc, low (Low) is indicated.

Accordingly, a predetermined duty ratio is set to give a desired voltage waveform, and by comparing the voltage waveform with the voltage waveform of the carrier wave, a PWM signal having a predetermined duty ratio in which voltage levels Hi and Low are repeated can be generated.

Fig. 5 is a diagram showing a configuration example of a control unit provided in the compressor 21. The control unit 50 includes a power supply circuit (also referred to as a rectifier circuit) 51 as an example of the first inverter circuit included in the INV41, an inverter bridge circuit 52 as an example of the second inverter circuit included in the INV41, and a microcomputer 53 as an example of the ODU 40.

The rectifier circuit 51 is connected to the commercial power source 42, and converts ac power from the commercial power source 42 into dc power using a rectifier diode 54, a smoothing capacitor 55, and the like. The rectifier diode 54 is an example of a rectifier unit that converts ac power into dc power, and the smoothing capacitor 55 is an example of a smoothing unit that smoothes the voltage of the converted dc power.

The inverter bridge circuit 52 includes a switching element 56 as an example of switching means for switching between on (on) and off (off), and operates the switching element 56 based on the dc power from the rectifier circuit 51 and the PWM signal from the microcomputer 53 to generate voltages (Vu, vv, vw) as 3 pulse waves to be applied to the motor 30. The switching element 56 is, for example, a field effect transistor (MOSFET) or the like.

The microcomputer 53 includes a motor drive control unit 57, a heating control unit 58, a signal generation unit 59, and a control switching unit 60. The microcomputer 53 includes at least a processor and a memory, and the memory stores a control program, and the processor reads out the control program from the memory and executes the control program, thereby realizing the above-described respective functional units such as the motor drive control unit 57. Note that, although all of the functional units may be realized by control programs, some or all of the functional units may be realized by hardware such as an ASIC (Application SPECIFIC INTEGRATED Circuit).

The motor drive control unit 57 is connected to the signal generation unit 59 by controlling the switching unit 60 during driving of the motor 30, calculates the pulse width of on/off of the PWM signal applied to the switching element 56 constituting the inverter bridge circuit 52 based on the measurement results of various sensors for measuring the discharge temperature, the indoor temperature, and the like of the compressor 21, and outputs the pulse width, thereby controlling the driving of the motor 30. The motor drive control unit 57 can output the duty ratio as the operation result.

When the motor 30 has stopped, the heating control unit 58 is connected to the signal generation unit 59 by controlling the switching unit 60, calculates the pulse width of on/off of the PWM signal applied to the switching element 56, and outputs the duty ratio as a result of the calculation, thereby performing heating control. The heating control unit 58 adjusts the duty ratio of at least one of the three phases as necessary, thereby adjusting the amount of current flowing through the coil. The purpose of heating the lubricating oil 33 when the motor 30 has stopped is to prevent foaming of the oil when the motor 30 is started next time.

The signal generating unit 59 is, for example, a PWM generation timer or the like, and generates a PWM signal based on the duty ratio output from the motor drive control unit 57 and the heating control unit 58. The control switching unit 60 switches the connection destination to connect to the motor drive control unit 57 when the motor 30 is driven, and switches the connection destination to connect to the heating control unit 58 when the driving is stopped.

A shunt resistor 61 for measuring the direct current input from the rectifier circuit 51 to the inverter bridge circuit 52 is provided between the rectifier circuit 51 and the inverter bridge circuit 52. Further, by measuring the voltage of the smoothing capacitor 55, the dc voltage can be measured. The voltages and currents of the U-phase, V-phase, and W-phase of the motor 30 can be calculated based on the dc current and the dc voltage and PWM signals described above. The calculation method is known, and thus a detailed description is omitted here.

In order to achieve the desired heating by using the electromagnetic induction heating principle, an ac current of a high frequency needs to be supplied, but as described above, the switching loss of the switching element 56 increases, and it is necessary to cope with an increase in cost due to an expansion of a heat sink or the like.

In order to avoid this, in the above-described conventional technique, an alternating current is formed in a simulated manner by using a current delay caused by inductance of a coil of a motor, thereby reducing switching loss.

The prior art will be briefly described with reference to fig. 6. In this technique, a current is divided into a plurality of sections for 1 cycle, and when a PWM signal is generated, half of the divided sections are turned on, and the remaining half of the divided sections are turned off. In the example shown in fig. 6, the current 1 cycle is divided into 6 sections, 3 sections are on sections, and the remaining 3 sections are off sections. Thus, a PWM signal with a duty ratio of 50% is generated, and a current on the positive side of the ac flows in the on period and a current on the negative side of the ac flows in the off period.

With such section division, the PWM signals of the respective phases are generated by shifting the phases by 120 ° (2 section amounts) for the U-phase, V-phase, and W-phase. Thereby, the three-phase alternating current can be generated while reducing the switching period to the current period.

In this technique, only 1 phase of 3 phases, i.e., the U phase, can adjust the duty cycle from 50% to 33.3%. When the duty ratios of the 3 phases are 50% in total, when asymmetric pulse waves of the U phase, V phase, W phase, and U phase overlap, the three phases of high level, intermediate level, and low level are set, and the duration of the high level is the same as the duration of the low level. Therefore, an offset voltage that occurs in the difference between the duration of the high level and the duration of the low level is not generated.

On the other hand, when the duty ratio of the U phase is changed from 50%, an offset voltage is generated and applied as a direct current amount. Therefore, when the heating amount is insufficient, the direct current amount is applied by changing the duty ratio of the U phase, so that the copper loss of the copper coil can be increased to secure the heating amount. Copper loss is loss due to the resistive component of the coil.

In this way, the duty ratio of the PWM signal can be adjusted, and the amount of current flowing through the coil can be adjusted.

The heating effect of the lubricating oil 33 varies depending on the characteristics of the permanent magnet and the coil and the position of the permanent magnet when the compressor is stopped. In the radio wave method, when the wave is more than 50W, approval of the ministerial general affairs is required. Therefore, in order to be used without acceptance, it is necessary to measure the electric power and adjust the current while changing the position of the permanent magnet. In this way, when a motor having a wide range of characteristics is used, the fluctuation of electric power increases, and adjustment of current becomes difficult, making it difficult to obtain desired heating.

Therefore, in the compressor 21 of the present embodiment, the control device 28 generates a rectangular wave signal for passing a current in a predetermined phase so that the positional relationship between the 3-phase coil and the permanent magnet becomes a predetermined positional relationship, and after adjusting the position of the permanent magnet, generates PWM signals for heating the lubricating oil 33 via the shaft 31 and passing a current in each phase. Thus, since the permanent magnet is positioned at a predetermined position when the motor 30 is driven, even when a motor having a wide range of characteristics is used, the fluctuation of electric power is reduced, and the adjustment of electric current becomes easy, so that desired heating can be obtained.

The heating control by the control unit 50 will be described with reference to fig. 7. The heating control unit 58 provided in the control unit 50 performs heating control when the compressor is stopped. In the heating control, a PWM signal for a predetermined coil is generated before the start of the heating operation for warming up the lubricating oil 33, and a current is caused to flow through the predetermined coil. The predetermined coil is a coil of a predetermined phase, for example, a coil of a U-phase. The coil of the predetermined phase is not limited to the U-phase but may be a coil of V-phase or W-phase. The current flowing through the predetermined coil is a direct current, and a torque for moving the rotor of the motor 30 is applied thereto.

In fig. 7, a plurality of rectangles are arranged, which represent on-times of the PWM signal, and blank portions between the rectangles represent off-times of the PWM signal. When a current flows through the U-phase coil before the start of the heating operation, the U-phase becomes N-pole, and attracts the S-pole of the permanent magnet, so that the S-pole of the permanent magnet approaches the U-phase, and the rotor 30b rotates.

The rotor 30b is intended to rotate through the U-phase due to the momentum of its rotation. Therefore, it is desirable that the magnetic force of the N pole generated in the U phase is identical to the magnetic force of the S pole generated in the V phase and the W phase, and the rotation is suppressed, and the magnetic force is fixed as a predetermined position at a position where the U phase serving as the N pole is opposed to the S pole of the permanent magnet. Therefore, only the U-phase coil flows a current, and the V-phase coil and the W-phase coil flow a current in half of each branch of the U-phase current. That is, as shown in fig. 8, half of the current of the opposite (negative) U phase flows in the V phase and the W phase.

Specifically, only the upper stage of the switching elements 56 of the upper and lower stages used for applying a voltage to the U-phase is on/off driven by the PWM signal. For the V-phase and W-phase, only the switching element 56 in the lower stage is on/off driven by the PWM signal. By controlling the permanent magnet in this manner, the permanent magnet can be fixed at a predetermined position.

The position where the permanent magnet is fixed is set as the position at the start of the heating operation, and a 3-phase PWM signal is applied, which is only an ac output, and a current is applied to the U-phase, V-phase, and W-phase coils, whereby the desired heating of the lubricating oil 33 can be obtained by electromagnetic induction heating. In this case, since the ac output is provided, the switching elements 56 of both the upper and lower stages facing the U-phase coil are alternately turned on and off, and the V-phase and W-phase are operated in the same manner.

As shown in fig. 9, the heating control section 58 controls as follows: 1 PWM signal is generated in 3 periods of the carrier signal, and 1 period of the alternating current flowing through the coil of the motor 30 is formed. The carrier signal is divided into a first half and a second half, and is set to 6 sections, and each section is set to a fixed section for turning on/off the PWM signal.

All of the 6 sections of the U-phase, V-phase, and W-phase may be fixed sections for turning on/off the PWM signal, or 1 section of any one of the U-phase, V-phase, and W-phase may be duty adjustment sections for switching on/off at arbitrary timing, so that the amount of current can be adjusted. Further, by changing the duty ratio in the duty ratio adjustment section, the direct current amount can be added.

However, when a 3-phase PWM signal of only ac output is applied or a direct current is applied thereto, the phases fixed at predetermined positions at the time of positioning, for example, the state of magnetic force balance between the U-phase and the other 2 phases, that is, the V-phase and the W-phase is broken, the magnetic force generates a magnitude relationship, and the rotor 30b rotates. Therefore, it is necessary to adjust the duty ratio so that the state of magnetic force balance is not destroyed.

Specifically, the duty ratio of the fixed phase is set to a value smaller than the other 2 duty ratios, and a direct current is applied to the fixed phase. When the fixed phase is the U phase, the N pole can be generated in the U phase by applying a direct current to the U phase, and therefore the S pole of the permanent magnet can be fixed at a position facing the coil of the U phase.

Fig. 10 is a flowchart showing an example of the flow of the present heating control. The heating of the lubricating oil 33 by the present heating control can be started from the stage in which the motor 30 has stopped, but may be started at any time when the motor 30 has stopped, or may be started when the outside air temperature at the time when the motor 30 has stopped becomes lower than the 1 st threshold. When a sensor or the like for measuring the temperature of the lubricating oil 33 is provided at an arbitrary timing at which the motor 30 has stopped, for example, when the temperature of the lubricating oil 33 is lower than the 2 nd threshold value by the sensor or the like can be cited.

From step 100, in step 101, the heating control unit 58 sets the duty ratio of the PWM signal to be applied to the switching element 56 of the predetermined phase so that the positional relationship between the 3-phase coil and the permanent magnet becomes a predetermined positional relationship, and the signal generating unit 59 generates the PWM signal for the predetermined phase based on the duty ratio.

In step 102, the inverter bridge circuit 52 generates a pulse wave of a predetermined phase based on the dc power from the rectifier circuit 51 and the PWM signal input from the signal generator 59, applies the pulse wave to a predetermined phase of the motor 30, and positions the permanent magnets so that the positional relationship between the 3-phase coil and the permanent magnets of the rotor becomes a predetermined positional relationship. For example, the permanent magnet is positioned such that the S pole of the permanent magnet is positioned to face the U-phase coil, which is a predetermined phase.

At the stage when the positioning of the permanent magnet is completed, the heating operation is started, and in step 103, the heating control unit 58 sets the duty ratio of the PWM signal applied to the switching element 56 of 3 phases, and the signal generating unit 59 generates the PWM signal for 3 phases based on the duty ratio.

In step 104, the inverter bridge circuit 52 generates a 3-phase pulse wave from the dc power from the rectifier circuit 51 and the PWM signal inputted from the signal generator 59, inputs the pulse wave to the 3-phase coil, and heats the lubricating oil 33 through the shaft 31 by electromagnetic induction heating by flowing an ac current through the 3-phase coil.

The control of the heating control unit 58 is performed until the connection to the signal generation unit 59 is switched from the heating control unit 58 to the motor drive control unit 57 by the control switching unit 60.

Fig. 11 is a diagram illustrating another example of the current flowing through each phase in the preparatory operation before the heating operation. As in fig. 8, fig. 11 (a) shows a mode in which positive current flows in the U phase, negative current flows in half of the U phase in the opposite directions in the V phase and the W phase, and fig. 11 (b) shows a mode in which positive current flows in the U phase and the V phase, and negative current 2 times of the U phase flows in the W phase.

Fig. 11 (c) shows a mode in which positive current flows through the V-phase and negative current flows through half of the V-phase in the U-phase and W-phase, and fig. 11 (d) shows a mode in which negative current flows through the U-phase and positive current flows through half of the U-phase in the V-phase and W-phase. Fig. 11 (e) shows a mode in which a positive current flows through the W-phase and a negative current flows through the U-phase and the V-phase, respectively, and fig. 11 (f) shows a mode in which a negative current flows through the V-phase and a positive current flows through the U-phase and the W-phase, respectively, and a positive current flows through the V-phase and the V-phase, respectively.

The position of the permanent magnet can be fixed at a predetermined position regardless of which of these modes the current flows.

As described above, by providing the compressor, the air conditioning apparatus, and the heating method according to the present invention, a motor having a wide range of characteristics can be used, and the compressor, the air conditioning apparatus, and the heating method can be provided at low cost. In addition, the fluctuation of the electric power during the heating operation is small, the adjustment of the current amount is easy, and the desired heating can be realized.

The compressor, the air conditioning apparatus, and the heating method according to the present invention have been described in detail with reference to the above embodiments, but the present invention is not limited to the above embodiments, and may be modified within the scope of the present invention as long as the present invention has the functions and effects, and the present invention is within the scope of any one of the embodiments, including other embodiments, additions, modifications, and deletions, which can be considered by those skilled in the art.

Description of the reference numerals

10 … Air conditioner

11 … Indoor unit

12 … Indoor heat exchanger

13 … Indoor fan

14 … Driving motor for indoor fan

20 … Outdoor unit

21 … Compressor

22 … Four-way valve

23 … Outdoor expansion valve

24 … Outdoor heat exchanger

25 … Outdoor fan

26 … Driving motor for outdoor fan

27 … Liquid storage device

28 … Control device

30 … Motor

30A … stator

30B … rotor

31 … Shaft

32 … Compression mechanism

33 … Lubricating oil

34 … Container

35 … Suction inlet

36 … Outlet

40…ODU

41…INV

42 … Commercial power supply

43 … Transmission line

44-46 … Coil

50 … Control part

51 … Rectifying circuit

52 … Inverter bridge circuit

53 … Microcomputer

54 … Rectifier diode

55 … Smoothing capacitor

56 … Switch element

57 … Motor drive control unit

58 … Heating control portion

59 … Signal generating section

60 … Control switch

61 … Shunt resistor.

Claims

1. A kind of compressor, in which the compressor is composed of a casing, characterized by comprising:

a motor provided with a plurality of windings and a magnet;

A rotation shaft rotated by the motor;

a compression mechanism that compresses a fluid by rotation of the rotation shaft;

a lubricant oil which is supplied to a sliding part of the compressor through the rotation shaft; and

A control unit that generates a rectangular wave signal for flowing a current in a winding of the motor,

The control means generates rectangular wave signals for predetermined windings such that the positional relationship between the plurality of windings and the magnet becomes a predetermined positional relationship, and generates rectangular wave signals for the windings in order to heat the lubricating oil via the rotating shaft after the position of the magnet is adjusted.

2. The compressor of claim 1, wherein,

The control means includes a plurality of switching means for switching between energized and non-energized, and when adjusting the position of the magnet, the switching means for operating is switched based on the rectangular wave signal to change the amount of current flowing through the plurality of windings.

3. A compressor according to claim 2, wherein,

The control means switches the switching means for performing the operation for each heating operation in which the compressor is stopped and the lubricating oil is heated.

4. The compressor of claim 1, wherein,

The control unit generates each rectangular wave signal so that a period of each rectangular wave signal is equal to a period of a current flowing through each winding after the position of the magnet is adjusted.

5. The compressor of claim 4, wherein,

The control unit adjusts at least one duty cycle in the rectangular wave signal.

6. The compressor of claim 1, wherein,

The control unit includes:

A first conversion unit that converts ac power from a commercial power source into dc power;

A second conversion unit that generates a voltage to be applied to the motor so as to flow a current through a winding of the motor, based on the dc power and the rectangular wave signal;

a signal generation unit that generates a rectangular wave signal for generating a voltage to be applied to the motor; and

And a heating control unit that sets a duty ratio for generating the rectangular wave signal.

7. An air conditioning apparatus comprising a compressor, characterized in that,

The compressor includes:

a motor provided with a plurality of windings and a magnet;

A rotation shaft rotated by the motor;

The control means generates a rectangular wave signal for a predetermined winding such that the positional relationship between the plurality of windings and the magnet becomes a predetermined positional relationship, and generates a rectangular wave signal for each winding for warming the lubricating oil via the rotating shaft after the position of the magnet is adjusted.

8. A heating method for heating lubricating oil in a compressor,

The compressor includes:

a motor provided with a plurality of windings and a magnet;

A rotation shaft rotated by the motor;

A lubricant oil which is supplied to a sliding portion of the compressor through the rotation shaft; and

A control unit for generating a rectangular wave signal for passing a current through a winding of the motor in order to heat the lubricating oil through the rotating shaft,

It is characterized in that the method comprises the steps of,

The heating method comprises the following steps:

The control unit generates a rectangular wave signal for a predetermined winding such that a positional relationship between the plurality of windings and the magnet becomes a predetermined positional relationship;

after the position of the magnet is adjusted, the control unit generates a rectangular wave signal for each winding in order to heat the lubricating oil via the rotating shaft; and

The motor is applied with a voltage generated by a rectangular wave signal for each winding, and the lubricating oil is heated by electromagnetic induction heating via the rotating shaft.