JP2005086911A - Controller for compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for a compressor by which the vibration of the compressor can be suppressed, and moreover, in which an increase of an input is remarkably small. <P>SOLUTION: The controller for a compressor has the compressor 105, a synchronous motor 103, a position detecting means 111, and an inverter 102. When the synchronous motor 103 is in a state of a low rotational frequency, the inverter 102 makes an alternating current flow so as to switch a current signal of the motor at regular time intervals regardless of the output of the position detecting means 111. Therefore, the occurrence of the oscillations due to the fluctuations of load torque of the compressor can be significantly suppressed while suppressing the increase of the input. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inverter-driven compressor mainly used in a refrigerator-freezer or an air conditioner, and in particular, controls a compressor (for example, a reciprocating type or a rotary type) having a compression element whose load torque fluctuates during one rotation. It relates to the device.

  Brushless motors have high efficiency, and in recent years, they have come to be used in many compressors used in refrigeration systems. Further, it is well known that a brushless motor can easily change the number of rotations of a voltage applied to the motor by pulse width modulation control (hereinafter referred to as PWM control).

  For this reason, in refrigerator-freezers and air conditioners, when the temperature is stable, the number of revolutions is reduced, the efficiency of the entire refrigeration system including the compressor is increased, and energy saving is realized.

  However, in a reciprocating compressor often used in a refrigerator-freezer, half of one rotation is a refrigerant suction process, and the latter half is a compression / discharge process. Therefore, almost no load torque is required in the suction process, but a large load torque is required in the compression / discharge process.

  The motor torque of the brushless motor generates a substantially constant torque during one rotation, and therefore, the number of rotations (that is, angular velocity) fluctuates during one rotation due to the relationship between the load torque and the motor torque. This fluctuation in the rotational speed becomes a factor of vibration generation, which has been a major obstacle to lowering the rotational speed for further energy saving.

  The same applies to rotary compressors often used in air conditioners. Even if not as much as reciprocating, there is a similar load torque pulsation due to the relationship between the suction process and the compression / discharge process during one rotation. Due to the same principle, a large vibration occurs at a low rotational speed.

  Also, at high speeds, the energy due to the moment of inertia of the compressor rotation system (rotor, shaft, piston, etc.) is sufficiently large, and the load torque pulsation can be sufficiently canceled out. This vibration is not a problem. Become a thing.

  In response to these phenomena, conventionally, efforts have been made to suppress compressor vibration by generating a motor torque that matches the load torque at low speed rotation and suppressing fluctuations in rotation speed during one rotation. (For example, refer to Patent Document 1).

  A conventional compressor control device will be described below with reference to the drawings.

  FIG. 12 is a longitudinal sectional view of a general reciprocating compressor. The motor is composed of a stator 21 having a three-phase winding in a hermetic container 1 and a rotor 22 having a permanent magnet, a cylinder 5, a piston 6 and the like arranged on the bearing body 4 and the rotor 22 are fitted. And a compression mechanism portion including a rotary shaft 3 and the like for converting the rotational motion into the reciprocating motion of the piston 6 by the eccentric portion 31.

  In general, an internal vibration isolation structure is used in a reciprocating compressor, that is, discharged from a support spring 8 that supports a structure composed of the electric motor 2 and the compression mechanism, or a compression mechanism. A technique is adopted in which vibration of the structure due to torque fluctuation generated according to a load is attenuated by a loop pipe 9 or the like for guiding gas to control vibration or noise.

  In the reciprocating compressor, the rotor 22 and the rotating shaft 3 should have an appropriate moment of inertia, together with a structure that attenuates the vibration of the structure by the support spring 8 and the loop pipe 9. Therefore, it is devised so that vibration is not transmitted to the outside of the sealed container 1.

  However, when this reciprocating compressor is controlled to change the rotation speed using inverter control, vibration suppression by the moment of inertia reaches its limit, especially in the low rotation speed area, and structurally suppressing vibration It becomes extremely difficult.

  In addition, the rotary compressor is in a more severe situation. FIG. 13 is a longitudinal sectional view of a general rotary compressor. The rotary motion from the electric shaft 44 and the rotary shaft 45 comprising the stator 42 having the three-phase winding in the hermetic container 41 and the rotor 43 having the permanent magnet and the rotary shaft 45 is directly in the compression element 46 through the bearing portion 47. The cylinders and pistons (not shown) perform the compression work while rotating. In particular, unlike the reciprocating type, the stator 42 of the electric motor 44 is generally directly connected (welded or the like) to the sealed container 41.

  Therefore, there is no means for attenuating the vibration of the structure due to torque fluctuation generated according to the load, such as the support spring 8 and the loop pipe 9 that the reciprocating compressor shown in FIG. It will be transmitted to the outside of the machine.

  FIG. 14 shows a relationship diagram between load torque and motor torque of a conventional compressor.

  In FIG. 14, as a method for controlling the motor torque, a method in which a position detection element is installed in the motor, instantaneous torque is detected, and feedback to the motor output is most effective. In the case where the pressure condition for gas compression is determined by linking to a certain degree of temperature, the motor output torque pattern is set in advance according to the ambient temperature, the internal temperature, and the rotation speed, and the optimum pattern according to the change in the condition. It is also possible to select a method.

  The difference between the load torque and the motor output torque becomes zero or greatly reduced by giving the motor a torque having the same absolute value as that of the load torque variation pattern, or approximately equal and the opposite of the sign of the sign. Further, vibration transmitted to the outside is greatly reduced.

Changing the motor torque according to the rotational position is generally realized by controlling the motor current (for example, Patent Document 2). This utilizes the characteristic that the torque generated by the brushless motor is approximately proportional to the current. By controlling the motor current in accordance with the load torque at the rotational position, the difference between the motor torque and the load torque is greatly reduced to suppress vibration.
JP 2003-4352 A Japanese Patent Laid-Open No. 2-79793

  However, in the conventional configuration, the motor torque, that is, the motor current is varied in accordance with the variation of the load torque, so that the motor current during one rotation varies greatly. The fluctuation of the motor current causes a decrease in average motor efficiency, and as a result, there is a problem that the input increases.

  Further, in order to detect the motor current and control the current value, the number of current sensors and their circuits has increased, and there has been a problem of increasing the size and cost.

  In order to solve the above-described problems, the present invention provides a compressor control apparatus that can suppress the vibration of a compressor to the same extent as that of the conventional method and that has a significantly small increase in input compared to the conventional method. Objective.

  It is another object of the present invention to provide a compressor control device that is compact and inexpensive without adding a new circuit.

  The present invention detects a compressor having a compression element whose load torque fluctuates during one rotation, a synchronous motor having a permanent magnet for driving the compression element in a rotor, and a position of the rotor of the synchronous motor. A position detecting means, and an inverter for causing an alternating current to flow in accordance with the position detecting means and making the rotation speed variable and making the refrigeration capacity of the compressor variable. The AC current is made to flow at regular intervals regardless of the output of the position detection means. This allows the motor current signal to be switched without synchronizing with the position detection signal. When the angular velocity is temporarily reduced, for example, the motor current is advanced with respect to the rotational position, the d-axis current automatically increases in the negative direction and is weak. Working magnetic flux control has the effect that increasing the rotation speed. On the other hand, when the angular velocity temporarily increases, the motor current is flowed at an angle with respect to the rotational position, so the d-axis current automatically decreases and conversely rotates in the positive direction. Decrease the number.

  In the compressor control apparatus according to the present invention, the motor current signal can be switched without synchronizing with the position detection signal. Therefore, when the motor rotation state, for example, the angular velocity temporarily decreases, the motor current is rotated. Since the current is advanced with respect to the position, the d-axis current automatically increases in the negative direction, and the flux-weakening control works to increase the rotational speed.

  On the other hand, when the angular velocity temporarily increases, the motor current is flowed at an angle with respect to the rotational position, so the d-axis current automatically decreases and conversely rotates in the positive direction. Has the effect of reducing the number. Thereby, generation | occurrence | production of the vibration by the fluctuation | variation of the load torque of a compressor can be suppressed significantly.

  In addition, by setting the average phase difference during one rotation between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed to be not less than 0 degrees and less than 10 degrees, the synchronous motor is most optimally efficient. It has the effect of being able to drive in various situations. Accordingly, since the entire drive can be operated in the most efficient state, the input is minimized and energy saving can be realized. Here, the phase difference is a predetermined value determined by the structure of the rotor of the motor.

  In addition, by setting the phase difference between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed to be -20 degrees or more and 30 degrees or less, the angular speed can be obtained with a small increase in input as a synchronous motor characteristic. Therefore, the compressor can be significantly suppressed without increasing the input.

  Further, if the phase difference between the rotational position of the rotor at a low rotational speed and the alternating current output from the inverter is outside the predetermined range, the phase difference is determined by increasing or decreasing the voltage or current output from the inverter. By making it fall within the range, the input increases slightly from the above, but the vibration of the compressor can be greatly reduced.

  In addition, by changing the phase of the output current of the inverter with respect to the position detecting means during one rotation at a low rotation speed, the rotational state of the synchronous motor can be grasped more accurately and the angular velocity can be controlled according to the state. Because the fluctuation of the angular speed can be further reduced, the vibration of the compressor caused by the fluctuation of the angular speed due to the fluctuation of the load torque of the compressor can be more accurately and reliably suppressed while suppressing the increase in input. Can do.

  Further, one rotation is divided into a plurality of sections (n is an integer of 2 or more), and the output current of the inverter for the position detecting means is divided for each of the sections so that the angular velocity of each section is constant. By changing the phase, it is possible to easily suppress fluctuations in the angular velocity using an inexpensive control element such as a microcomputer. Therefore, it is possible to realize vibration suppression without increasing the input of the inexpensive control element.

  In addition, if the angular velocity is smaller than a predetermined value, the phase of the current is advanced, and if the angular velocity is larger than the predetermined value, the phase of the current is delayed, so that the angular velocity can be easily and accurately made constant. Vibrations due to load torque fluctuations can be greatly reduced without an increase in input.

  In addition, by setting the average phase difference during one rotation between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed to be not less than 0 degrees and less than 10 degrees, the synchronous motor is most optimally efficient. Therefore, it is possible to minimize the input while suppressing the vibration and to realize a significant energy saving.

  In addition, by setting the phase difference between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed to be -20 degrees or more and 30 degrees or less, the angular speed can be obtained with a small increase in input as a synchronous motor characteristic. Therefore, the effect of suppressing vibration without increasing the input can be obtained.

  Further, if the phase difference between the rotational position of the rotor at a low rotational speed and the alternating current output from the inverter is outside the predetermined range, the phase difference is determined by increasing or decreasing the voltage or current output from the inverter. If the variation in angular velocity cannot be sufficiently suppressed in the above-described state by making it within the range, the increase in input can be minimized and the variation in angular velocity can be minimized by further increasing or decreasing the voltage or current. Since it can be minimized, more effective vibration suppression can be realized.

  In addition, as a compressor using these controls, a reciprocating compressor having a reciprocating compression element enables effective angular velocity per rotation even in a reciprocating compressor in which load torque is concentrated in half of one rotation. It can be kept constant, and vibrations due to torque pulsations can be significantly suppressed without increasing the input even at low rotations that cannot be realized structurally, and significant energy savings can be realized by reducing the number of rotations.

  Similarly, since the compressor using these controls is a rotary compressor having a rotary compression element, the load torque fluctuation in one rotation is in the whole area, but the load torque fluctuation is structurally related. Even with a rotary compressor that has a large impact, the angular velocity per rotation can be kept constant, so even if structurally the fluctuations in load torque have a large impact, including surrounding piping, Low input and low vibration can be achieved even at low speeds, and significant energy savings can be achieved.

In addition, these compressors drive a refrigeration and air-conditioning system for cooling or heating by connecting a crimper, a decompressor, an evaporator, etc., to circulate the refrigerant. Since the instability of the angular velocity due to load torque fluctuation is significantly reduced, it is possible to realize significant low vibration and significant energy saving.

    The invention according to claim 1 of the present invention includes a compressor having a compression element whose load torque fluctuates during one rotation, a synchronous motor having a rotor as a permanent magnet for driving the compression element, and the synchronous motor. A position detecting means for detecting the position of the rotor, and an inverter for causing an alternating current to flow in accordance with the position detecting means and for making the refrigeration capacity of the compressor variable by varying the rotational speed. In the case of a number, the inverter causes an alternating current to flow so as to be switched at regular intervals regardless of the output of the position detection means, whereby the current signal of the motor is not synchronized with the position detection signal. Since the motor current is advanced with respect to the rotational position when the rotational speed of the motor, for example, the angular velocity temporarily decreases, the d-axis current is automatically The now many directions, flux-weakening control works, has an effect that increases the rotational speed. On the other hand, when the angular velocity temporarily increases, the motor current is flowed at an angle with respect to the rotational position, so the d-axis current automatically decreases and conversely rotates in the positive direction. Has the effect of reducing the number.

  According to a second aspect of the present invention, in the first aspect of the invention, the average phase difference during one rotation between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed is 0 degree. The angle is less than 10 degrees, and this has the effect that the synchronous motor can be operated in an optimum situation where the efficiency is highest.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the phase difference between the rotational position of the rotor at a low rotational speed and the alternating current output from the inverter is -20 degrees or more and 30 degrees. Accordingly, as a characteristic of the synchronous motor, there is an effect that the fluctuation of the angular velocity can be suppressed to be smaller than that in the conventional state with a small increase in input.

  According to a fourth aspect of the invention, there is provided the invention according to any one of the first to third aspects, wherein a phase difference between the rotational position of the rotor at a low rotational speed and the alternating current output from the inverter is predetermined. If the voltage is out of the range, the voltage or current output from the inverter is increased or decreased so that the phase difference falls within the predetermined range. When fluctuations in angular velocity are not sufficiently suppressed even when the phase difference from the AC current is set to -20 degrees or more and 30 degrees or less, the voltage or current is increased or decreased to minimize the increase in input. Fluctuation can be minimized.

  According to a fifth aspect of the present invention, there is provided a compressor having a compression element whose load torque fluctuates during one rotation, a synchronous motor having a permanent magnet for driving the compression element in a rotor, and the synchronous motor. A position detecting means for detecting the position of the rotor, and an inverter for causing an alternating current to flow in accordance with the position detecting means and changing the rotational speed to make the compressor refrigerating capacity variable. The phase of the output current of the inverter with respect to the position detecting means is changed during one rotation in the rotation, and the rotation state of the synchronous motor can be grasped with higher accuracy and the angular velocity can be controlled according to the state. Variation can be reduced.

  Further, in the invention described in claim 6, in the invention described in claim 5, one rotation is divided into a plurality of n sections that are integers of 2 or more, and the angular velocity of each section is constant. The phase of the output current of the inverter with respect to the position detecting means is changed for each of the plurality of sections, and thereby, the effect that the fluctuation of the angular velocity can be easily suppressed using an inexpensive control element such as a microcomputer. Have.

The invention according to claim 7 is the invention according to claim 5 or 6, wherein the phase of the current is advanced if the angular velocity is smaller than a predetermined value, and the phase of the current is delayed if the angular velocity is larger than the predetermined value. Thus, the angular velocity can be easily and accurately made constant.

  The invention according to claim 8 is the invention according to any one of claims 5 to 7, wherein the rotation position of the rotor at a low rotational speed and the alternating current output from the inverter are in one rotation. The average phase difference is not less than 0 degrees and less than 10 degrees, and this has the effect that the synchronous motor can be operated in an optimum situation where the efficiency is highest.

  Further, the invention according to claim 9 is the invention according to any one of claims 5 to 8, wherein the phase difference between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed is − As a characteristic of the synchronous motor, there is an effect that the fluctuation of the angular velocity can be suppressed smaller than that in the conventional state with a small increase in input.

  According to a tenth aspect of the present invention, in the invention according to any one of the fifth to ninth aspects, the phase difference between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed is predetermined. Is outside the range, the voltage or current output from the inverter is increased or decreased so that the phase difference falls within a predetermined range. Even if the phase difference from the AC current output from the inverter is set to -20 degrees or more and 30 degrees or less, fluctuations in angular velocity cannot be sufficiently suppressed, and the increase in input is minimized by further increasing or decreasing the voltage or current. Therefore, the fluctuation of the angular velocity can be minimized.

  The invention according to claim 11 is the invention according to any one of claims 1 to 10, wherein the compressor having a compression element whose load torque fluctuates during one rotation is a reciprocating compression element. Thus, even in a reciprocating compressor in which the load torque is concentrated in half of one rotation, the angular velocity per one rotation can be effectively maintained constant.

  According to a twelfth aspect of the invention, in the invention according to any one of the first to tenth aspects, the compressor having a compression element whose load torque fluctuates during one rotation has a rotary compression element. Although this is a rotary compressor, the load torque fluctuation during one rotation is spread over the whole area, but even in the rotary compressor where the influence of the load torque fluctuation is large due to its structure, it is effective per revolution. The angular velocity can be kept constant.

  The invention according to claim 13 is the invention according to claim 11 or 12, wherein the compressor is connected to a condenser, a decompressor, an evaporator or the like to circulate the refrigerant, thereby cooling or heating. This drives the refrigeration and air-conditioning system for performing the operation, and has the effect that the instability of the angular velocity due to load torque fluctuation is remarkably reduced even at low speed rotation.

  Embodiments of a compressor control apparatus according to the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram of a compressor control apparatus according to Embodiment 1 of the present invention.

In FIG. 1, a commercial power source 100 is, for example, an AC power source in the case of Japan, and is a 100 V 50 Hz or 60 Hz power source. In this embodiment, the rectifier circuit 101 that converts the commercial power supply 100 into a direct current is shown as a full-wave rectifier circuit that is generally composed of four bridge-connected diodes and a smoothing capacitor. With this full-wave rectifier circuit, a DC voltage of 140 V is obtained from the AC 100 V of the commercial power supply 100.

  The inverter 102 that converts the DC voltage of the rectifier circuit 101 back into three-phase AC is generally connected in reverse to the six switching elements (indicated by IGBT in the figure) connected in a three-phase bridge and the switching elements in parallel. 6 diodes. By controlling these six switching elements, a three-phase alternating current having an arbitrary voltage and an arbitrary frequency can be obtained.

  The synchronous motor 103 driven by the three-phase AC output of the inverter 102 includes a stator (not shown) with windings and a rotor (not shown) having permanent magnets. For example, the stator is a 9-slot tooth wound directly through insulating paper, and a 3-phase 6-pole winding is star-connected. The rotor has 6 permanent magnets on the surface side with N and S poles. And embedded magnet type rotors arranged alternately.

  The output from the inverter 102 can be set to an arbitrary voltage / arbitrary frequency, and the synchronous motor 103 has 6 poles. Therefore, the synchronous motor 103 is driven at a frequency (rotational speed) that is one third of the output frequency of the inverter 102. The For example, when the output frequency of the inverter 102 is 60 Hz, the rotation speed of the synchronous motor 103 can be driven at 20 r / s, and when the output frequency of the inverter 102 is 240 Hz, the rotation speed of the synchronous motor 103 can be driven at 80 r / s.

  The compression element 104 whose load torque varies during one rotation driven by the synchronous motor 103 is a compression element whose load torque varies during one rotation, such as a reciprocating type or a rotary type. In the case of a reciprocating type compression element, compression is performed by reciprocating movement of a piston, and half of the suction process and half of the compression process are completely separated from each other during one rotation. The torque fluctuates greatly. In the case of a rotary type compression element, the suction process and the compression process are simultaneously performed per rotation, so it is not as extreme as the reciprocating type, but the load torque in the compression / discharge process is large, and again per rotation. The load torque fluctuation of the is large.

  The compressor 105 stores the synchronous motor 103 and the compression element 104 in a sealed container. It goes without saying that any refrigerant gas may be used, and any refrigerant gas such as an alternative refrigerant (R-134a, etc.) or a natural refrigerant (R-600a, CO2, etc.) may be used.

  The compressor 105 includes a discharge pipe that discharges the compressed refrigerant and a suction pipe that sucks the refrigerant. A condenser 106, a decompressor 107, an evaporator 108, and the like are connected in series to the discharge pipe, and finally the refrigerant gas returns from the suction pipe to the compressor 105. By assembling such a refrigerating and air-conditioning system, a heat dissipation action occurs on the condenser 106 side and a heat absorption action occurs on the evaporator 108 side, so that heating or cooling can be performed.

  Further, a fan motor is attached to the condenser 106 or the evaporator 108 and air is sent to increase the efficiency of heat exchange, so that these heats can be used effectively and heated or cooled efficiently.

  The output of the drive device 109 for driving the inverter 102 drives the six switching elements of the inverter 102 via the drive means 110.

In general, when driving a synchronous motor 103 having a permanent magnet as a rotor, the six switching elements of the inverter 102 are commutated at optimum positions while detecting the rotational position of the rotor, thereby synchronizing the rotor. The motor 103 is moved optimally. In general, a motor using this method is sometimes referred to as a brushless DC motor or a brushless motor.

  Further, the contents of the control device 109 will be described in detail.

  The position detector 111 detects the rotational position of the rotor of the synchronous motor 103. In general, a method for detecting the counter electromotive voltage generated in the stator winding of the synchronous motor 103 is well known, but recently, a method for estimating the rotational position from the motor current or the current of the DC section is also often used. It has been broken. Of course, there is a method of directly detecting the position using a magnetic sensor such as a Hall element. However, since it is difficult to attach such a sensor to a compressor, the former method (position sensorless method) is often used. Yes.

  In such a position sensorless system, since position detection is impossible at the time of start-up, a predetermined phase (for example, between U and W) of the synchronous motor 103 called positioning is forcibly energized before start-up so that the rotor is predetermined. A control circuit such as a method of rotating to a position or a forcible drive system for forcibly applying an AC waveform of a predetermined frequency and a predetermined voltage to drive the rotor is also necessary, but is omitted here.

  The commutation means 112 determines the timing for energizing the six switching elements of the inverter 102 based on the output of the position detection means 111. In general, the timing is determined so that the phase of the counter electromotive voltage coincides with the phase. However, in the case of a magnet-embedded motor (generally called an IPM motor), the reluctance torque is also taken into consideration and the motor current is slightly increased. There are also cases in which the operation is advanced with respect to the phase of the counter electromotive voltage. Although this phase advance varies depending on the type of motor (especially the amount of reluctance component used), it is common to have an advance angle of about 0 to 10 degrees.

  Since the output of the position detecting means 111 detects the rotational position of the rotor of the synchronous motor 103, the rotational speed detecting means 113 analyzes the signal of the position detecting means 111 to thereby detect the rotational speed of the synchronous motor 103. (Or including rotation period, angular velocity, etc.) can be detected.

  Depending on the state of the refrigerating and air-conditioning system, the rotation speed is supported by the refrigerating and air-conditioning system control device (not shown). The PWM voltage setting means 114 uses a PWM (pulse width modulation) control duty (predetermined period, referred to as a carrier period) so that this rotation speed and the actual rotation speed detected by the rotation speed detection means 113 coincide with each other. Adjust the ON width ratio).

  By driving the six switching elements of the inverter 102 via the drive means 110 by the output of the PWM voltage setting means 114 and the output of the commutation means 112, the synchronous motor 103 is driven, and the optimum Highly efficient operation is realized by operating with a simple motor current phase.

  The synchronization signal generating means 115 generates a signal synchronized with the rotational speed detected from the rotational speed detecting means 113. For example, when the rotational speed detected by the rotational speed detection means 113 is 20 r / s, since the drive signal is 60 Hz, a synchronization signal of 60 Hz is output from the synchronization signal generation means 115.

  Further, when the rotation speed detected by the rotation speed detection means 113 is lower than a predetermined rotation speed, the selection means 116 selects a signal from the synchronization signal generation means 115 as a signal to be sent to the drive means 110. If the rotation speed detected by the rotation speed detection means 113 is higher than a predetermined rotation speed, the signal from the commutation means 112 is selected as a signal to be sent to the drive means 110.

  Of course, the selection operation of the selection means 116 is performed only when it is stable, and when it is not stable such as in a transition period, the output of the commutation means 112 that is more stable is selected.

  The operation of the compressor control apparatus configured as described above will be described in more detail with reference to FIGS. FIG. 2 is a flowchart of control in Embodiment 1 of the present invention.

  In FIG. 2, the number of rotations is detected at STEP1. Using the signal from the position detection unit 111, the rotation number detection unit 113 performs the operation. Although the number of rotations is used here, it may be the same as the number of rotations, for example, a rotation cycle or an angular velocity.

  Next, in STEP2, it is determined whether the operation is stable. The determination of the stable operation may be made from the temperature condition of each part in the refrigeration air-conditioning system control device (not shown) or the elapsed time. When it is determined that the operation is not stable, that is, in the transition period, it is important that the operation is stable. Therefore, in STEP 3, the signal generated by the commutation unit 112 based on the signal from the normal position detection unit 111 is used. The selection means 116 selects a signal so as to drive the six switching elements.

  If it is determined in STEP2 that the operation is stable, the process proceeds to STEP4. In STEP4, the rotational speed detected in STEP1 is compared with a predetermined value. This predetermined value is determined by the configuration of the refrigeration air-conditioning system, the type of compressor, the inertia of the rotor of the motor, and the like, and the number of rotations at which vibration due to load torque pulsation generated at a low speed of the compressor is to be suppressed is set. Of course, a predetermined value that varies depending on the surrounding environment state (temperature, etc.) and the driving state may be determined.

  When the rotational speed is larger than the predetermined value in STEP4, the operation based on the position detection in STEP3 is selected as described above. If the rotational speed is equal to or less than the predetermined value in STEP4, the process proceeds to STEP5.

  In STEP 5, the selection unit 116 performs selection so that the inverter 102 is driven in a synchronous operation by the synchronization signal generation unit 115. Here, it is characterized in that switching is performed at regular intervals at a timing unrelated to the signal of the position detection means 111. For example, when 20 r / s is detected by the rotation speed detection means 113, the synchronous motor 103 is a 6-pole motor, so that the inverter 102 outputs a frequency 60 Hz that is three times as high. For example, in the case of a 120-degree conduction type inverter, switching is always sequentially switched at a constant cycle, and in the case of a sine wave inverter, a waveform whose phase always changes every constant time is output.

  Next, in STEP 6, the phase detected by the position detecting means 111 and the output phase of the inverter 102 by the synchronizing signal generating means 115 are compared, and the average phase per rotation is calculated. The duty by the PWM voltage setting means 114 is increased or decreased so that the average phase is 0 degrees to 10 degrees (advance direction). When the average phase is smaller than 0 degrees, the duty is increased, and when the average phase is larger than 10 degrees, the duty is decreased, and adjustment is performed so that the average phase falls within a desired range.

  Next, in STEP 7, the phase detected by the position detector 111 and the output phase of the inverter 102 by the synchronization signal generator 115 are compared, and the maximum phase and the minimum phase per rotation are detected. If the maximum phase and the minimum phase are within a predetermined range (for example, −20 degrees or more and 30 degrees or less), nothing is done, but if it is smaller than −20 degrees, for example, the duty of that portion is determined by the PWM voltage setting means 114. If the duty is smaller than the determined duty and larger than 30 degrees, the duty of the portion is made larger than the duty determined by the PWM voltage setting means 114 to adjust the partial speed (angular velocity).

  Next, the actual operation will be described with reference to FIG. FIG. 3 is a control timing chart according to Embodiment 1 of the present invention.

  In FIG. 3, the horizontal axis indicates the movement of the synchronous motor 103 during one rotation. A broken line written on the horizontal axis indicates the mechanical rotation state detected by the position detecting means 111, and one segment indicates 1 / 18th rotation. In this embodiment, since the synchronous motor 103 has six poles, the mechanical rotation state (one-third rotation and two-third rotation) per one electrical angle cycle is further indicated by a one-dot chain line. ing.

  As for torque, load torque and motor torque are shown, and since the compressor 105 is a reciprocating compressor, the load torque enters the compression / discharge process after a half rotation of the mechanical rotation state. The torque increases rapidly as shown. On the other hand, the motor torque generates a substantially constant torque per rotation. Strictly speaking, the motor torque automatically changes as shown in Patent Document 1 when the inertial moment is small at a low rotation speed in accordance with the change of the load torque. The torque was constant.

  The angular velocity fluctuates during one rotation, and the angular velocity is accelerated when “motor torque> load torque”, while the angular velocity is decelerated when “motor torque <load torque”. This change in angular velocity is a factor that causes vibration at low speed.

  The positions of the position signals X, Y, and Z change every 1 / 18th rotation (that is, every 20 degrees) of the mechanical rotation state. In normal control, drive signals U (upper arm and lower arm), V (upper arm and lower arm), W (upper arm and lower arm) are determined according to a predetermined logical expression in accordance with the position signals X, Y, and Z. Is generated. However, in the present embodiment, switching is always performed at a constant period T1 regardless of the position signals X, Y, and Z. This T1 is set to 1 / 18th of a mechanical rotation period T.

  As described above, regardless of the position signals X, Y, and Z, fluctuations in angular velocity are generated by generating the drive signals U (upper and lower arms), V (upper and lower arms), and W (upper and lower arms). The mechanism by which becomes smaller will be described in more detail.

  4 is a diagram illustrating the principle of control when the actual angular velocity is equal to the driving angular velocity according to the first embodiment of the present invention. FIG. 5 is a diagram illustrating the principle of control when the actual angular velocity is smaller than the driving angular velocity according to the first embodiment. 6 is an explanatory diagram of the principle of control when the actual angular velocity> the driving angular velocity in the embodiment.

  Here, the actual angular velocity indicates a mechanical angular velocity, and the driving angular velocity indicates an angular velocity based on a motor current output from the inverter 102. The waveform shows the drive voltage supplied from the inverter 102 and the induced voltage generated in the synchronous motor 103 for a predetermined phase (for example, U phase).

  In FIG. 4, since “actual angular velocity = drive angular velocity”, switching is performed at the same timing as switching in synchronization with the position signal of the position detection unit 111. At this time, since the drive is set so as to be the most efficient, it is set to be slightly advanced. This is because the structure of the rotor of the synchronous motor 103 is an embedded magnet (IPM) motor so that the reluctance torque can be used effectively. Although this optimum angle depends on the structure of the motor, in general, an advance angle of about 0 to 10 degrees is desirable. This advance angle is the average advance angle throughout.

In FIG. 5, since “actual angular velocity <drive angular velocity”, the cycle of the induced voltage is wider than the cycle of the drive voltage. Therefore, the drive voltage is applied in a state advanced with respect to the induced voltage.

  In FIG. 6, since “actual angular velocity> driving angular velocity”, the cycle of the induced voltage is narrower than the cycle of the driving voltage. Therefore, the drive voltage is applied in a state delayed from the induced voltage.

  The above situation will be further described in detail using a vector diagram.

  FIG. 7 is a vector diagram of control when the actual angular velocity = drive angular velocity in the first embodiment of the present invention, FIG. 8 is a vector diagram of control when the actual angular velocity <drive angular velocity in the embodiment, and FIG. FIG. 5 is a vector diagram of control when actual angular velocity> drive angular velocity in the embodiment.

  Here, the q axis is in the direction of generating the magnet torque of the motor, and the d axis is in the direction of generating the weakening magnetic flux.

  In FIG. 7, since “actual angular velocity = driving angular velocity”, the driving is performed in a slightly advanced state as described above. The terminal voltage Vt is advanced by δ0 with respect to the q axis, and accordingly, the current is also advanced by β0. This is not for performing the flux-weakening control, but for efficient use of the reluctance torque, a slight advance is performed and efficient operation is performed.

  In FIG. 8, since “actual angular velocity <drive angular velocity”, the terminal voltage Vt is advanced by δ1 with respect to the q axis, and the current is also advanced by β1. At this time, the d-axis current id increases in the negative direction, and the flux-weakening control (the d-axis current acts to suppress the induced voltage caused by the permanent magnets of the rotor and the apparent amount of magnetic flux decreases. The induced voltage is reduced. Because it is suppressed, high-speed operation is possible than usual). By this action, an operation for increasing the actual angular velocity is performed.

  In FIG. 9, since “actual angular velocity <drive angular velocity”, the terminal voltage Vt is delayed by δ2 with respect to the q-axis, and the current is also delayed by β2. At this time, the d-axis current id is in the plus direction, and an operation for reducing the actual rotational speed is performed contrary to the previous case.

  Therefore, by these operations, when the actual angular velocity is small, the angular velocity is increased, and conversely, when the actual angular velocity is large, the angular velocity is decreased, thereby changing the angular velocity to the conventional driving method. Compared to this, it becomes extremely small.

  The state at this time will be further described with reference to FIG. FIG. 10 is a characteristic diagram showing changes in the rotational speed and the motor current when the advance angle is changed in the first embodiment of the present invention. The horizontal axis represents the current advance angle, and the vertical axis represents the rotation speed and motor current. The number of revolutions is indicated by a broken line, and the motor current is indicated by a solid line.

  When the advance angle of the current is between −20 degrees and 30 degrees, the motor current does not change significantly, and the rotation speed changes. By performing control during this time, there is almost no change in current, and only the rotation speed can be changed.

When the advance angle is -20 degrees or less, the current suddenly rises, and when the advance angle is 30 degrees or more, the current rises suddenly. is there. That is, when the angle is -20 degrees or less, the duty is decreased to control the angular velocity to be decreased, and when the angle is 30 degrees or more, the duty is increased to increase the angular velocity, thereby reducing the input and Control that suppresses effective angular velocity fluctuations can be performed.

  As described above, the compressor control apparatus according to the first embodiment has the compressor 105 having the compression element 104 whose load torque varies during one rotation and the permanent magnet that drives the compression element 104 in the rotor. The synchronous motor 103, the position detecting means 111 for detecting the position of the rotor of the synchronous motor 103, and the alternating current is passed in accordance with the position detecting means 111, and the revolving speed is made variable to make the refrigeration capacity of the compressor 105 variable. The inverter 102 is synchronized with the position detection signal by flowing an alternating current so that the inverter 102 is switched at regular intervals regardless of the output of the position detection means 111 at a low rotation speed. Without switching the motor current signal, the motor current rotates when the motor rotation status, for example, the angular velocity temporarily decreases Because flows in advance with respect to location, d-axis current is automatically increases in the negative direction, flux-weakening control works, has an effect that increases the rotational speed. On the other hand, when the angular velocity temporarily increases, the motor current is flowed at an angle with respect to the rotational position, so the d-axis current automatically decreases and conversely rotates in the positive direction. Has the effect of reducing the number.

  Thereby, generation | occurrence | production of the vibration by the fluctuation | variation of the load torque of a compressor can be suppressed significantly. Also, the input at this time will not be as high as before. In addition, since it can be realized by simple control by simply switching the output waveform of the inverter every predetermined time, no new sensor or high-performance CPU is required, which contributes to the miniaturization and cost reduction of the circuit.

  In addition, by setting the average phase difference during one rotation between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed to be not less than 0 degrees and less than 10 degrees, the synchronous motor is most optimally efficient. It has the effect of being able to drive in various situations. Accordingly, since the entire drive can be operated in the most efficient state, the input is minimized and energy saving can be realized. Here, the phase difference is a predetermined value determined by the structure of the rotor of the motor. Even in the realization of this control, the conventional position detecting means 111 can be used, which contributes to the miniaturization and cost reduction of the circuit.

  In addition, by setting the phase difference between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed to be -20 degrees or more and 30 degrees or less, the angular speed can be obtained with a small increase in input as a synchronous motor characteristic. Therefore, the compressor can be significantly suppressed without increasing the input.

  Further, if the phase difference between the rotational position of the rotor at a low rotational speed and the alternating current output from the inverter is outside the predetermined range, the phase difference is determined by increasing or decreasing the voltage or current output from the inverter. By making it fall within the range, the input increases slightly from the above, but the vibration of the compressor can be greatly reduced.

  In addition, since these controls can be realized with exactly the same configuration as the conventional configuration, no new sensor or high-performance CPU is required, which contributes to the miniaturization and cost reduction of the circuit.

  In the first embodiment, the output waveform of the inverter 102 is a rectangular wave driven by 120 degrees, but it goes without saying that the effect is not changed at all even if the output waveform is a sine wave or other trapezoidal wave. Further, the position detecting means 111 is a method for detecting the induced voltage of the synchronous motor 103, but the same effect can be obtained even when a method for detecting the rotational position from the motor current or a mechanical sensor such as a Hall element is used. . Although the synchronous motor 103 is an IPM type motor, the same effect can be obtained by a surface magnet type (SPM) motor.

(Embodiment 2)
Next, Embodiment 2 will be described with reference to FIG. FIG. 11 is a flowchart of control in Embodiment 2 of the present invention.

  First, the rotation period is detected in STEP10. Here, the rotation period is a result of dividing one rotation into a plurality of n sections (n is an integer of 2 or more) and measuring the sections. The position detection unit 111 can divide into sections of at least 20 degrees. In addition, since the position detection angle is detected by the apparatus that detects the position using a motor current or the like, detection at an arbitrary angle is possible.

  Next, in STEP 11, the rotation cycle detected in STEP 10 is compared with a predetermined value determined in advance from the command rotational speed. If the rotation period is equal to the predetermined value, the process proceeds to STEP12. In STEP 12, the current phase is maintained as it is.

  In STEP 11, if the rotation period is larger than the predetermined value, the rotation speed is slower than the predetermined value, so that it is necessary to increase the rotation speed. Therefore, the current is advanced and driven in phase in STEP13. In this case, it is effective to use this advance phase in the next cycle by making use of the fact that the load torque of the compressor changes periodically instead of making the phase advance immediately after detection.

  Next, in STEP14, it is confirmed whether the lead phase is the limit. The advance phase limit here is 30 degrees as described above, but it varies depending on the type of motor. When the advance phase has not yet reached the limit, it is left as it is. When the limit is reached, the current greatly increases in the forward phase beyond this, and therefore, the operation of making the period constant without increasing the current significantly is performed by increasing the duty of the PWM control.

  In STEP 11, if the rotation period is smaller than the predetermined value, the rotational speed is faster than the predetermined value, so it is necessary to reduce the rotational speed. In STEP 16, the current is driven with a delayed phase. In the same way as described above, it is effective to use this delay phase in the next cycle by utilizing the fact that the load torque of the compressor changes periodically, instead of making the phase advance immediately after detection. .

  Next, in STEP 17, it is confirmed whether the delay phase is the limit. The limit of the delay phase here is optimal at −20 degrees as described above, but also varies depending on the type of motor. When the delay phase has not yet reached the limit, it is left as it is. When the limit is reached, the current greatly increases at a delay phase longer than this, and therefore the operation is performed to make the cycle constant without increasing the current by decreasing the duty of the PWM control.

  As described above, the compressor control apparatus according to the second embodiment changes the phase of the output current of the inverter with respect to the position detection means during one rotation at a low rotation speed, thereby rotating the synchronous motor more accurately. Because the situation can be grasped and the angular speed can be controlled according to the state, the fluctuation of the angular speed can be further reduced, so the vibration of the compressor caused by the fluctuation of the angular speed due to the fluctuation of the load torque of the compressor can be input. In the state where the increase in the number is suppressed, it can be more accurately and reliably suppressed.

  Further, one rotation is divided into a plurality of sections (n is an integer of 2 or more), and the output current of the inverter for the position detecting means is divided for each of the sections so that the angular velocity of each section is constant. By changing the phase, it is possible to easily suppress fluctuations in the angular velocity using an inexpensive control element such as a microcomputer. Therefore, it is possible to realize vibration suppression without increasing the input of the inexpensive control element.

In addition, if the angular velocity is smaller than a predetermined value, the phase of the current is advanced, and if the angular velocity is larger than the predetermined value, the phase of the current is delayed, so that the angular velocity can be easily and accurately made constant. Vibrations due to load torque fluctuations can be greatly reduced without an increase in input.

  In addition, by setting the average phase difference during one rotation between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed to be not less than 0 degrees and less than 10 degrees, the synchronous motor is most optimally efficient. Therefore, it is possible to minimize the input while suppressing the vibration and to realize a significant energy saving.

  In addition, by setting the phase difference between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed to be -20 degrees or more and 30 degrees or less, the angular speed can be obtained with a small increase in input as a synchronous motor characteristic. Therefore, the effect of suppressing vibration without increasing the input can be obtained.

  Further, if the phase difference between the rotational position of the rotor at a low rotational speed and the alternating current output from the inverter is outside the predetermined range, the phase difference is determined by increasing or decreasing the voltage or current output from the inverter. If the variation in angular velocity cannot be sufficiently suppressed in the above-described state by making it within the range, the increase in input can be minimized and the variation in angular velocity can be minimized by further increasing or decreasing the voltage or current. Since it can be minimized, more effective vibration suppression can be realized.

  In addition, as a compressor using these controls, a reciprocating compressor having a reciprocating compression element enables effective angular velocity per rotation even in a reciprocating compressor in which load torque is concentrated in half of one rotation. It can be kept constant, and vibrations due to torque pulsations can be significantly suppressed without increasing the input even at low rotations that cannot be realized structurally, and significant energy savings can be realized by reducing the number of rotations.

  Similarly, since the compressor using these controls is a rotary compressor having a rotary compression element, the load torque fluctuation in one rotation is in the whole area, but the load torque fluctuation is structurally related. Even with a rotary compressor that has a large impact, the angular velocity per rotation can be kept constant, so even if structurally the fluctuations in load torque have a large impact, including surrounding piping, Low input and low vibration can be achieved even at low speeds, and significant energy savings can be achieved.

  These compressors connect condensers, pressure reducers, evaporators, etc., and circulate the refrigerant to drive a refrigeration and air conditioning system for cooling or heating. Since the instability of the angular velocity due to torque fluctuation is remarkably reduced, it is possible to realize a significant low energy and a significant energy saving.

  As described above, the present invention can greatly suppress the occurrence of vibration due to fluctuations in the load torque of the compressor, and can be widely applied to the product field using a compressor such as a refrigeration air conditioner.

The block diagram of the control apparatus of the compressor in Embodiment 1 of this invention Flow chart of control in the embodiment Timing chart of control in the same embodiment Explanatory drawing of control principle when actual angular velocity = drive angular velocity in the same embodiment Explanatory drawing of control principle when actual angular velocity <drive angular velocity in the same embodiment Explanatory drawing of control principle when actual angular velocity> drive angular velocity in the same embodiment Vector diagram of control when actual angular velocity = drive angular velocity in the embodiment Vector diagram of control when actual angular velocity <drive angular velocity in the same embodiment Vector diagram of control when actual angular velocity> drive angular velocity in the embodiment Characteristic diagram showing changes in rotation speed and motor current when the advance angle is changed in the same embodiment Flow chart of control in Embodiment 2 of the present invention Vertical section of a general reciprocating compressor Vertical section of a general rotary compressor A characteristic diagram showing the relationship between load torque and motor torque of a conventional compressor

Explanation of symbols

102 Inverter 103 Synchronous motor 104 Compression element 105 Compressor 109 Control device

Claims (13)

  A compressor having a compression element whose load torque fluctuates during one rotation, a synchronous motor having a permanent magnet for driving the compression element in the rotor, and a position detection means for detecting the position of the rotor of the synchronous motor; And an inverter for causing the refrigeration capacity of the compressor to be variable by flowing an alternating current in accordance with the position detection means and making the rotation speed variable, so that the inverter is connected to the position detection means at a low rotation speed. A compressor control device that allows an alternating current to flow so as to switch at regular intervals regardless of output.   2. The compressor according to claim 1, wherein an average phase difference during one rotation between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed is 0 degree or more and less than 10 degrees. Control device.   The compressor control according to claim 1 or 2, wherein a phase difference between a rotational position of the rotor at a low rotational speed and an alternating current output from the inverter is -20 degrees or more and 30 degrees or less. apparatus.   If the phase difference between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed is outside the predetermined range, the voltage difference or current output from the inverter is increased or decreased to reduce the phase difference to the predetermined range. The compressor control device according to any one of claims 1 to 3, wherein the compressor control device is placed inside.   A compressor having a compression element whose load torque fluctuates during one rotation, a synchronous motor having a permanent magnet for driving the compression element in the rotor, and a position detection means for detecting the position of the rotor of the synchronous motor; And an inverter for making the refrigeration capacity of the compressor variable by causing an alternating current to flow in accordance with the position detecting means and making the rotational speed variable, and an inverter for the position detecting means during one rotation at a low rotational speed A control device for a compressor, wherein the phase of the output current of the compressor is changed.   One rotation is divided into a plurality of n sections that are integers of 2 or more, and the phase of the output current of the inverter with respect to the position detecting means is changed for each of the plurality of sections so that the angular velocity of each section is constant. The compressor control device according to claim 5, wherein the control device is a compressor.   7. The compressor control according to claim 5, wherein the phase of the current is advanced if the angular velocity is smaller than a predetermined value, and the phase of the current is delayed if the angular velocity is larger than the predetermined value. apparatus.   8. The average phase difference during one rotation between the rotational position of the rotor and the AC power output from the inverter at a low rotational speed is set to 0 degree or more and less than 10 degrees. The compressor control device according to claim 1.   9. The phase difference between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed is set to −20 degrees or more and 30 degrees or less. 9. Compressor control device.   If the phase difference between the rotational position of the rotor and the alternating current output from the inverter at a low rotational speed is outside the predetermined range, the voltage difference or current output from the inverter is increased or decreased to reduce the phase difference to the predetermined range. The compressor control device according to any one of claims 5 to 9, wherein the compressor control device is placed inside.   The compressor control device according to any one of claims 1 to 10, wherein the compressor having a compression element whose load torque fluctuates during one rotation is a reciprocating compressor having a reciprocating compression element. .   The compressor control device according to any one of claims 1 to 10, wherein the compressor having a compression element whose load torque fluctuates during one rotation is a rotary compressor having a rotary compression element.   The compressor is configured to drive a refrigerating and air-conditioning system for cooling or heating by connecting a condenser, a decompressor, an evaporator and the like to circulate the refrigerant. Item 13. The compressor control device according to Item 12.

Images