JP2007181336A - Motor drive device and storage device incorporating it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a motor drive device applicable to refrigerators and the like, by improving the practical usage and reliability of the device in which a rectifier circuit is substantially miniaturized and its cost is cut. <P>SOLUTION: This motor drive device comprises an inverter control device 112 that uses a voltage obtained by rectifying an AC power supply 1 as an input of an inverter 5 to drive a brushless motor 6 stably, a regeneration process circuit 25 that, installed between the rectifier circuit 2 and the inverter 5, connects a second rectification portion 26 in series to a regeneration absorption portion 27, a voltage detection means 30 that detects a voltage of the regeneration absorption portion 27, and a revolution setting means 31 that determines target revolutions of a brushless motor 6. When the drive is commanded with the target revolutions lower than the present revolutions of the brushless motor 6, the regeneration generated during the deceleration period of the brushless motor 6 is suppressed by reducing the revolutions of the brushless motor 6 so that the voltage of the regeneration absorption portion 27 detected by the voltage detection means 30 can be maintained at a predetermined level or lower. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor drive device that drives and controls a brassless motor by an inverter, and a storage device such as a refrigerator that includes the motor drive device.

  FIG. 5 is a block diagram showing a configuration of a conventional motor driving apparatus for driving a brushless DC motor. In the following description, the conventional motor driving apparatus shown in FIG.

  In FIG. 5, the first conventional technique includes an AC power supply 101, an inductor 102, a rectifier diode 103, a smoothing capacitor 104, an inverter 106, a brushless motor 107, a position sensor 108, a drive circuit 109, and a control circuit 110. .

  In order to input DC power to the inverter 106, when the AC voltage from the AC power supply 101 is converted into a DC voltage using the rectifier diode 103 and the smoothing capacitor 104, the current from the AC power supply 101 is used for smoothing. It flows only when the voltage of the capacitor 104 is smaller than the input AC voltage. For this reason, the current from the AC power supply 101 is a current with a harmonic component.

  Therefore, in the first prior art, the inductor 102 is provided between the AC power supply 101 and the rectifier diode 103 in order to reduce the harmonic component and improve the power factor.

  As described above, in the first conventional technique, the rectifier circuit 105 uses the inductor 102 and the smoothing capacitor 104 in addition to the rectifier diode 103.

  Further, when the brushless motor 107 is driven by an inverter, information on the rotation angle of the rotor is necessary.

  For this reason, in the first prior art, the rotation angle of the rotor is detected using the position sensor 108 (see, for example, Patent Document 1).

  The inductor 102 and the smoothing capacitor 104 of the rectifier circuit 105 used in the first prior art are often large components having large inductance or capacitance. For this reason, many conventional motor driving devices are large and expensive.

  From this point of view, in the field of motor drive devices, miniaturization and cost reduction of the devices are desired, and small components such as inductors with low inductance or capacitors with low capacitance are used, or these components are used. The construction of a rectifier circuit that does not use the circuit has been studied.

  Therefore, a motor driving device that does not use an inductor and a smoothing capacitor as shown in FIG. 6 has been proposed. Hereinafter, the configuration shown in FIG. 6 will be described as a second prior art.

  In the second prior art, since no smoothing capacitor is used, the input to the inverter 106 is not a DC voltage maintaining a constant voltage but a voltage waveform having pulsation.

  When a voltage having such a pulsation is input to the inverter 106, a desired voltage to be applied to the brushless motor 107 may not be formed in the inverter 106 when the input voltage to the inverter 106 is low.

  In the second prior art, when such a desired voltage cannot be obtained, the phase of the voltage applied to the brushless motor 107 is advanced. Since the so-called field weakening state can be achieved by advancing the phase of the applied voltage to the brushless motor 107 in this way, the applied voltage required for the brushless motor 107 can be reduced.

  Therefore, the second conventional technique is a technique capable of continuing to drive the brushless motor 107 even when the input voltage to the inverter 106 is low.

  However, in the second prior art, the switching operation of the inverter 106 is stopped when the input voltage to the inverter 106 becomes equal to or lower than a predetermined value. This is because there is a limit to driving the motor in the field-weakening state.

  As described above, the second conventional technique is a technique in which no voltage is applied to the brushless motor 107 when the input voltage to the inverter 106 is equal to or lower than a predetermined voltage value (for example, a patent) Reference 2).

  Moreover, in the motor drive device, a device that does not use a position sensor is desired from the viewpoint of wireless wiring and cost reduction.

  Therefore, a method for detecting the motor current and estimating the rotor position of the brushless motor has been proposed. Hereinafter, this technique will be described as a third conventional technique.

  The third prior art uses the motor current, the voltage value applied to the brushless motor at that time, and the motor constants such as the resistance value and inductance of the brushless motor, and calculates the rotor position of the motor by the phase estimation calculation formula based on the voltage equation. (For example, refer nonpatent literature 1).

  In addition to downsizing the motor drive device, it is possible to cope with either a configuration using a position sensor and a configuration without a position sensor, and even if the input voltage of the inverter pulsates greatly, There has also been proposed a motor drive device that can be stably driven without a position sensor without stopping the application of voltage to the brushless motor (see, for example, Patent Document 3). Hereinafter, this technique will be described as a fourth conventional technique.

  FIG. 7 is a block diagram showing the fourth prior art.

  The fourth prior art is a configuration in which an AC power supply 101 is converted into DC power having pulsation by a rectifier diode 103 and input to an inverter 106. The inverter 106 converts the rectified DC power into AC power, and applies a desired voltage to the brushless motor 107. Further, a small-capacitance capacitor 111 is inserted between the rectifier diode 103 and the inverter 106 in order to avoid destruction of the device due to regeneration.

  The inverter control unit 112 includes a dq conversion unit 113, a d-axis PI controller 114, a q-axis PI controller 115, and a PWM generation unit 116, and includes an input voltage to the inverter 106, a motor current Id flowing through the brushless motor 107, Iq and motor current command values Id * and Iq * indicating values that should flow to the brushless motor 107 are input. Here, “*” attached to the previous current command value is for distinguishing from the driving currents Id and Iq, and the specific current values are also different.

  When the input voltage value to the inverter 106 is smaller than the voltage value to be applied, the voltage phase of the applied voltage to the brushless motor 107 is maintained and the inverter 106 is controlled, so that the DC side voltage of the inverter 106 is Even when the voltage is low, the voltage is continuously applied without stopping the voltage application to the brushless motor 107.

In addition, even when a large pulsating voltage is input to the inverter 106, stable driving is realized, and the motor driving device is reduced in size.
JP-A-9-74790 (FIG. 1) Japanese Patent Laid-Open No. 10-150795 (page 3-5, FIG. 1) Japanese Patent Laid-Open No. 2005-20986 Takeshita, Ichikawa, Lee, Matsui, "Sensorless salient pole type brushless DC motor control based on speed electromotive force estimation", IEEJ Transactions D, 1997, Vol. 117, No. 1, p. 98-104

  However, the first prior art uses a position sensor to detect the rotor position of the brushless motor 107, and uses an inductor or a smoothing capacitor 104 to set the input voltage to the inverter 106 as a DC voltage. Therefore, since the inductor 102 and the smoothing capacitor 104 are large components having large inductance or capacitance, it is difficult to reduce the size of a motor driving device using these components.

  The second prior art is a motor drive device that detects the rotor position of the brushless motor 107 using a position sensor, and does not use large parts such as an inductor or a smoothing capacitor.

  Therefore, the second conventional technique is effective from the viewpoint of miniaturization and cost reduction. However, in the second prior art, since the input voltage to the inverter 106 pulsates, there is a problem that the application of the voltage to the brushless motor 107 is stopped when the input voltage is a predetermined value or less.

  Therefore, a position sensorless system that achieves a reduction in size and cost by combining the second conventional technique that does not use an inductor or a smoothing capacitor and the third conventional technique that is configured to drive a motor without a position sensor. When trying to construct a motor driving apparatus, there are the following problems.

  In the motor driving device having such a configuration, the position of the rotor cannot be estimated during a period in which the voltage application to the brushless motor 107 is stopped, and thus the brushless motor 107 cannot be driven without a position sensor. That is, it is impossible to construct a motor driving device in which the input voltage to the inverter 106 pulsates without a position sensor by simply combining the second conventional technique and the third conventional technique.

  Further, the fourth prior art solves these problems, realizes stable driving even when there is a large pulsation in the inverter input voltage, and enables downsizing and cost reduction of the device. Further, by inserting a capacitor 111 having a small electrostatic capacity between the rectifier diode 103 and the inverter 106, destruction of the device due to regeneration when the motor is stopped is prevented.

  However, in this configuration, it is necessary to select a capacitor having a capacitance that can reliably absorb the regenerative energy generated when the operation of the brushless motor 107 is decelerated or when the brushless motor 107 is stopped. It is necessary to increase the capacitance of the capacitor as the maximum rotational speed and the induced voltage constant increase.

  Therefore, the fourth prior art requires a capacitor having a large capacitance for a motor having a larger induced voltage constant and a higher driving speed, and a capacitor having a larger capacitance is required. There are problems associated with an increase in the size and cost of the motor drive device, such as the need for a harmonic suppression inductor due to the increase in the harmonic component contained in the current.

  An object of the present invention is to solve the above-described conventional problems, and to avoid failure of the apparatus due to regeneration that occurs when the brushless motor is stopped or decelerated while suppressing the power harmonic current. The fourth prior art is more practical.

  In order to solve the above-described conventional problems, the motor driving device of the present invention uses a voltage including pulsation obtained by rectifying an AC power supply as an input of an inverter, converts the voltage to a desired voltage by the inverter, and outputs the voltage to a brushless motor. And an inverter control unit that stably drives the brushless motor, and a regenerative absorption unit that is connected in parallel with a rectifier circuit configured of a rectifier diode, and absorbs and accumulates the regeneration of the brushless motor. The voltage detection means connected in series and detects the voltage of the regenerative absorption path, and the rotation speed setting means for determining the rotation speed of the brushless motor, the rotation speed setting means is the rotation of the current brushless motor When instructing driving at a rotational speed lower than the number, the brushless mode is set so that the voltage of the regenerative absorption section detected by the voltage detecting means is kept below a predetermined voltage. The rotation of the motor is gradually what was set to be reduced.

  Thereby, the regeneration which generate | occur | produces at the time of deceleration of a brushless motor can be suppressed, and the generated regeneration energy can be absorbed effectively.

  The motor drive device according to the present invention realizes stable brushless motor drive even when the output voltage from the rectifier circuit including pulsation is input to the inverter, and avoids device destruction due to regeneration that occurs during deceleration of the brushless motor. Therefore, it is possible to provide a small, low-cost and highly reliable motor drive device.

  In addition, the storage using such a motor drive device can be used as a compressor drive device, and as a result, as described above, the volume in the store increases with the miniaturization of the motor drive device. In addition, along with the reliability of the motor drive device, it is possible to prevent an increase in the internal temperature due to a circuit failure due to regeneration, and to improve the reliability of the storage.

  The invention described in claim 1 includes a rectifier circuit that performs full-wave rectification using an AC power supply as an input, an inverter that receives an output voltage of the rectifier circuit that has a large pulsation, a brushless motor that is driven by the inverter, and the inverter An inverter control unit that controls the regenerative energy, a regenerative absorption unit that absorbs and accumulates regenerative energy of the brushless motor, a second rectifier unit connected in series to the input side of the regenerative absorption unit, and a voltage of the regenerative absorption unit When the voltage detection means is provided and the rotational speed of the brushless motor is driven at a speed lower than the current rotational speed, the voltage of the regenerative absorption unit detected by the voltage detection means is maintained at a predetermined voltage level or less. The rotational speed of the brushless motor is reduced.

  By setting it as this structure, the regeneration which generate | occur | produces when decelerating the rotational speed of a brushless motor can be suppressed.

  Therefore, when stopping or decelerating the brushless motor, a highly reliable motor drive that efficiently absorbs and avoids failure of the device due to regenerative energy without causing an abnormal level of regenerative energy. Equipment can be provided.

  According to a second aspect of the present invention, the regeneration absorption unit includes a capacitor, and when the voltage of the regeneration absorption unit detected by the voltage detection unit rises to a preset maximum voltage or more, the regeneration The current rotational speed of the brushless motor is maintained until the voltage of the absorption unit is lowered to a predetermined voltage level.

  Therefore, since the deceleration is further performed after the voltage of the regenerative absorption portion generated along with the deceleration of the brushless motor is reduced to a predetermined value, the reliability against circuit breakdown due to regeneration can be further improved. In addition, since the capacitor specifications need only be determined according to the set voltage of the regenerative absorption unit, the capacitance of the regenerative absorption unit can be reduced, resulting in a reduction in circuit size and cost. I can plan.

  According to a third aspect of the present invention, a regenerative energy consuming circuit that consumes the regenerative energy is provided in parallel with the regenerative absorption unit.

  With this configuration, it is possible to consume regenerative energy while decelerating the brushless motor. As a result, it is possible to suppress the voltage increase of the regenerative absorption unit accompanying the deceleration of the brushless motor, and the time for the voltage of the regenerative absorption unit to rise to the set maximum voltage becomes longer. Therefore, since the brushless motor is decelerated during that time, a long deceleration time can be secured, and as a result, the time for decelerating to the target rotational speed can be shortened.

  According to a fourth aspect of the present invention, the regenerative energy consumption circuit is a power supply circuit that supplies power to the inverter control unit.

  By adopting such a configuration, the number of parts in configuring the circuit can be reduced, and further miniaturization and cost reduction can be achieved.

  According to a fifth aspect of the present invention, the rectifier circuit includes a rectifier diode and a smoothing capacitor, and the capacitance of the smoothing capacitor is a capacitance of 0.2 μF or less per maximum output of 1 W of the inverter. It is a thing.

  By adopting such a configuration, EMC performance can be improved. As a result, it is possible to simplify a noise filter provided to eliminate malfunction or influence on peripheral devices, and further miniaturization and cost reduction are possible.

  In the invention described in claim 6, the capacitance of the capacitor constituting the regenerative absorption unit is set larger than the capacitance of the smoothing capacitor constituting the rectifier circuit.

  By adopting such a configuration, the size (capacity) of the capacitor of the regenerative absorption unit can be selected in combination with the miniaturization of the smoothing capacitor, and as a result, the range of allowable regenerative absorption voltage is expanded, and the device It is possible to make a setting according to the requirement, and the reliability can be improved.

  In a seventh aspect of the present invention, a rare earth magnet is used as the permanent magnet of the rotor of the brushless motor.

  With this configuration, the regenerative energy generated from the increase in the induced voltage constant of the brushless motor also increases. As a result, such a configuration is very effective for protection from device destruction due to regeneration, and high reliability can be ensured.

  According to an eighth aspect of the present invention, the brushless motor is used for driving a compressor constituting a refrigeration air conditioning system, and the compressor has a reciprocating configuration.

  With this configuration, when the compressor has a reciprocating configuration with a large moment of inertia (inertia), when the input voltage of the inverter fluctuates greatly due to the small capacity of the capacitor of the rectifier circuit (large pulsation occurs). Even in the case of a voltage including the same, there is almost no influence such as an increase in vibration or noise due to rotation spots of the motor. As a result, it is possible to provide a compact and low-cost compressor drive system with vibration and noise equivalent to those of a motor drive device using a large-capacity smoothing capacitor in a rectifier circuit.

  The invention according to claim 9 uses R600a as a refrigerant of the refrigerating and air-conditioning system.

  As a result, as compared with a compressor using R134a as a refrigerant, the piston becomes larger, so that the moment of inertia (inertia) of the motor is increased, and as a result, it is less susceptible to the influence of fluctuations in the input voltage. Therefore, it is possible to realize a very stable driving of a low noise and low vibration compressor when driving a small capacity capacitor.

  In a tenth aspect of the present invention, the motor driving device is a driving device for a storage device.

  As a result, it is possible to obtain a storage that avoids device failure due to regeneration, and as a result, a highly reliable storage device that eliminates loss of food corruption due to non-cooling in the storage due to circuit failure, etc. . Moreover, the volume in the store | warehouse | chamber which accommodates a foodstuff with the same external appearance can be enlarged by size reduction of a circuit.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals are given to the same configurations as those of the conventional examples or the embodiments described above, and detailed descriptions thereof will be omitted. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
FIG. 1 is a block diagram of a motor drive device according to Embodiment 1 of the present invention.

  In FIG. 1, an AC power source 1 is a commercial power source, which is AC 100 V, 50 Hz, or 60 Hz in Japan and is connected to a rectifier circuit 2. The rectifier circuit 2 includes a rectifier diode 3 in which four diodes indicated by reference numerals 3a, 3b, 3c, and 3d are bridge-connected, and a smoothing capacitor 4 having a small capacitance, and is full-wave rectified by the rectifier diode 3. The voltage is input to the smoothing capacitor 4. In the first embodiment, the smoothing capacitor 4 is described as an example using a multilayer ceramic capacitor having a capacitance of 1 μF. In recent years, the multilayer ceramic capacitor can be realized with a chip having a high withstand voltage and a large capacity. In the first embodiment, the above-mentioned multilayer ceramic capacitor is used as an example.

  Conventionally, a large capacity (several hundred μF in the case of 200 W output) electrolytic capacitor has been mainly used for this smoothing capacitor, and thus it has been difficult to reduce the size. By using the chip type, a very small driving device can be realized.

  Furthermore, the electrolytic capacitor needs to consider the life due to capacity loss due to ambient temperature or aging deterioration, etc. In the first embodiment, the reliability of the device can be improved by not using the electrolytic capacitor. it can.

  Conventionally, the capacitance of the smoothing capacitor is generally determined by the output capacity (W or VA) of the inverter 5, the input capacity (W or VA) of the entire driving device, the ripple content of the DC voltage, and the ripple current. It is determined in consideration of the characteristics of ripple current resistance of the smoothing capacitor. In consideration of these conditions, generally those having a capacity of about 2 to 4 μF / W are used.

  That is, in the case of an output capacity of 200 W, an electrolytic capacitor of about 400 to 800 μF was used. On the other hand, in the first embodiment, a capacitor having a capacitance of 0.2 μF / W or less is used as the capacitor 4. That is, in the case of an output capacity of 200 W, a capacitor of 40 μF or less is used.

  The inverter 5 has a configuration in which six sets of circuits each including a diode 5g connected in the opposite direction to the switching element 5a are used and these are connected in a three-phase bridge. Here, each switching element is indicated by a symbol 5a, 5b, 5c, 5d, 5e, 5f, and a diode is indicated by a symbol 5g, 5h, 5i, 5j, 5k, 5l. In the first embodiment, an FET is used for the inverter 5, but an IGBT or a bipolar transistor may be used.

  The brassless motor 6 is driven by the three-phase output of the inverter 5. The stator of the brushless motor 6 is provided with a three-phase star-connected winding, and this winding method may be concentrated winding or distributed winding. The rotor of the brushless motor 6 has a rare earth permanent magnet, and the arrangement method may be a surface magnet type (SPM) or a magnet embedded type (IPM). The permanent magnet may be a ferrite magnet or a rare earth magnet.

  In addition, when using the same magnet weight as the ferrite magnet for the above-mentioned permanent magnet, it is possible to improve the motor efficiency by using a rare earth magnet, and the same performance as a motor using a ferrite magnet. When the motor is used, the weight of the magnet can be reduced, so that the weight of the motor can be reduced.

  The compression element 7 is connected to the rotor shaft of the motor 6 and has a well-known configuration for sucking refrigerant gas, compressing it, and discharging it. The brushless motor 6 and the compression element 7 are accommodated in the same sealed container 8 to constitute a compressor 9.

  The discharge gas compressed by the compressor 9 constitutes a refrigeration air-conditioning system that returns to the suction of the compressor 9 through the condenser 10, the decompressor 11, and the evaporator 12, and the condenser 10 performs heat dissipation, Since the evaporator 12 absorbs heat, it can be cooled and heated.

  In addition, a heat exchanger may be further accelerated | stimulated using a fan etc. for the condenser 10 and the evaporator 12 as needed. Moreover, in this Embodiment 1, the said refrigeration air conditioning system is demonstrated by the case where it uses for the refrigerator 13 which is an example of a storage device, It is set as the structure which cools the inside 13a of the refrigerator 13 with the evaporator 12. FIG.

  The regeneration processing circuit 25 has a configuration in which a second rectifier circuit 26 and a regeneration absorber 27 are connected in series, and is connected in parallel with the rectifier circuit 2. As a result, the regenerative energy generated when the rotational speed of the brushless motor 6 is decelerated can be absorbed by the regenerative absorber 27 via the second rectifier circuit 26. As a result, it is possible to prevent the apparatus from being damaged due to regeneration of the brushless motor 6, and to improve the reliability of the apparatus.

  The second rectifier circuit 26 includes a diode, and the regenerative absorption unit 27 includes a capacitor, so that the circuit can be very simple and can be configured at low cost. If necessary, the second rectifier circuit 26 or the regeneration absorber 27 may be provided with a protective resistor or the like.

  Here, when a rare earth-based permanent magnet is used for the stator of the brushless motor 6, the regenerative energy generated is larger because the induced voltage constant is larger than that of a brushless motor using a ferrite-based permanent magnet.

  Therefore, when driving a stator brushless motor using a rare earth-based permanent magnet, if a capacitor having a small electrostatic capacity is used as a smoothing capacitor, the possibility of circuit destruction due to regeneration increases.

  However, in the first embodiment, the regenerative energy can be reliably absorbed by adding the regenerative processing circuit 25 as described above. Therefore, the smoothing capacitor 4 has a small capacitance, and a motor that realizes a small size and a low cost. In the drive device, the reliability of the drive device of the brushless motor using the rare earth permanent magnet can be improved.

  The power supply circuit 28 is a power supply supplied to the inverter control unit 112, and receives the voltage across the capacitor of the regenerative absorption unit 27 in the regenerative processing circuit 25. The voltage at both ends of the regenerative absorption unit 27 is obtained by smoothing the output of the rectifier circuit 2 by charging the charge through the second rectifier circuit 26 of the regenerative processing circuit 25. In the first embodiment, the voltage is normally maintained at about 140V. , Supplied to the power supply circuit 28.

  As described above, in the first embodiment, the regenerative processing circuit 25 is also used as a rectifying / smoothing circuit of the power supply circuit 28 to reduce the size, simplify, and reduce the cost of the circuit.

  Further, when regeneration occurs, regenerative energy is stored in the capacitor of the regenerative absorption unit 27, and the energy is consumed by the inverter control unit 112 via the power supply circuit 28 and the power supply circuit 28. The unit 112 plays a role as the regenerative energy consuming circuit 29, and contributes to shortening the time when the voltage level of the regenerative absorption unit 27 rises due to regeneration to a normal voltage level (about 140V in the present embodiment). ing.

  The voltage detection means 30 monitors the voltage of the regenerative absorption part 27 of the regenerative processing circuit 25, and the rotation speed setting means 31 determines the rotational speed at which the brushless motor 6 should be operated from input information such as the outside air temperature and switch input. Is set.

  The inverter control unit 112 controls the output of the inverter so as to drive the brushless motor 6 at the target rotational speed set by the rotational speed setting means 31, but the current drive rotational speed of the brushless motor 6 is lower than the target rotational speed. In this case, while monitoring the voltage of the regenerative absorption unit 27 detected by the voltage detection means 30 so as not to exceed a predetermined level, the rotational speed of the brushless motor is gradually decreased and finally driven at the target rotational speed. The speed of the brushless motor 6 is controlled. Further, when the detection level of the voltage detection means 30 becomes a predetermined value or more while the speed of the brushless motor 6 is being reduced, the deceleration command of the brushless motor 6 is stopped and the detection level of the voltage detection means 30 is lowered. Until then, the speed of the brushless motor 6 is controlled so as to maintain the rotational speed at that time.

  The inverter control unit 112 includes a dq conversion unit 113, a d-axis PI controller 114, a q-axis PI controller 115, and a PWM generation unit 116 that receive a signal from the current detector 113a. Since the configuration is exactly the same as the technology and the same operation is performed, the brushless motor 6 can be stably driven even when a voltage with a large variation is input to the inverter 5, and thus detailed description thereof is omitted.

  Next, the compressor 9 according to the first embodiment will be described with reference to FIG. FIG. 2 shows a cross-sectional view of the compressor.

  In FIG. 2, oil 14 is stored in a sealed container 8 of the compressor 9 and a refrigerant 15 of R600a is enclosed, and a brushless motor 6 including a stator 16 and a rotor 17 and a compression element 7 driven by the brushless motor 6 are provided. It is elastically supported by a spring or the like, and is configured such that vibration due to rotation of the brushless motor 6 is difficult to leak out of the compressor 9.

  The compression element 7 supports the main shaft portion 18 of the crankshaft 20 composed of the main shaft portion 18 and the eccentric shaft portion 19 to which the rotor 17 is fixed, and also includes a cylinder 22 having a compression chamber 21 and a compression chamber 21. A reciprocating type compression mechanism is configured by including a piston 23 that reciprocates within and a connecting means 24 that connects the eccentric shaft portion 19 and the piston 23.

  Therefore, in the first embodiment, even when the input voltage of the inverter 5 includes a large pulsation, the vibration due to the pulsation and the noise accompanying the vibration are generated outside the compressor 9 due to the characteristics and structure of the reciprocating compressor having a large inertia. It is hard to leak.

  In the first embodiment, since R600a having a lower refrigeration capacity than R134a refrigerant is used, it is necessary to make the compression chamber volume larger than the compressor for R134a in order to ensure equivalent cooling performance. The piston 23 is enlarged. Therefore, since the motor inertia is increased, even if the smoothing capacitor 4 of the rectifier circuit 2 has a very small capacity, it is possible to further reduce the influence of vibration and noise on the application of the inverter input voltage including a large pulsation. .

  The operation of the above configuration will be described below with reference to FIGS. 1, 3 and 4. FIG. Here, an arbitrarily set upper limit value V1 and intermediate value V2 are provided for the voltage of the regenerative absorption unit 27, and when the voltage value of the regenerative absorption unit 27 is between the intermediate value and the upper limit value, the brushless motor 6 is deferred, and the rotation speed of the brushless motor 6 will be described as control maintained at the rotation speed when the upper limit value V1 is reached.

  FIG. 3 is an operation flowchart of the motor drive device according to the first embodiment, and FIG. 4 is an operation timing chart of the motor drive device according to the first embodiment.

  In FIG. 3, section 1 is a case where the drive rotational speed of the motor (brushless motor) 6 and the command rotational speed match, and the voltage of the regeneration absorber 27 is a stable reference voltage (rectified and smoothed from the AC power supply) In the first embodiment, about 140V) is maintained, and the rotational speed of the brushless motor 6 is stably driven at the command rotational speed (80 r / s in the first embodiment).

  If this state is shown in the flowchart of FIG. 4, the current drive rotational speed and the command speed coincide with each other. The process proceeds from STEP 101 to STEP 301, the speed holding flag is cleared to “0”, and the current brushless motor 6 The rotation speed is maintained and the operation is continued (STEP 302).

  In section 2 shown in FIG. 3, the rotation speed setting means 31 changes the command rotation speed of the brushless motor 6. In this embodiment, 0 r / s, that is, a stop command is output.

  This state is determined in STEP 101 in FIG. 4 that the command speed is lower than the current rotational speed (80 r / s in the present embodiment 1) and proceeds to STEP 102. In this section 2, however, the speed is as shown in FIG. Since the holding flag is “0”, the process proceeds to STEP 103. In STEP 103, the voltage of the regenerative absorption unit 27 is confirmed by the voltage detection means 30.

  Next, in STEP 104, it is confirmed whether or not the voltage detected in STEP 103 is lower than the upper limit value (180 V in the first embodiment) V1, and if lower than the upper limit value V1, the speed holding flag is cleared to “0” in STEP 105. Thereafter, the brushless motor 6 is decelerated by the inverter control unit 112 in STEP106. Thereafter, the operation returns to STEP 101 and the operation is repeated.

  At this time, in FIG. 3, the rotation speed of the brushless motor 6 is reduced by the deceleration control, and the voltage of the regenerative absorption unit 27 accumulates the regenerative energy generated by the above-described deceleration, and the voltage gradually increases. .

  When the voltage of the regenerative absorption unit 27 reaches the upper limit value V1 with the increase in voltage of the regenerative absorption unit 27, it is determined in STEP104 shown in FIG. 4 to proceed to STEP110.

  In STEP 110, the speed holding flag is set to “1”, and then in STEP 111, the current rotational speed of the brushless motor 6 is held. Specifically, the inverter control unit 112 shown in FIG. 3 controls the speed of the brushless motor 6. After the processing of STEP111, the process returns to STEP101.

  After the above-described operation, in STEP 101, since the command speed, that is, “stop” has not yet been reached, the process proceeds to STEP 102. Here, since section 3 shown in FIG. 3 is in a state in which the speed holding flag is set to “1”, the process proceeds to STEP 201 to detect the voltage of regenerative absorption unit 27 and to determine an intermediate value (this embodiment 1). Then, it is determined whether or not the voltage is 160V) V2 or less.

  Here, if the intermediate value V2 has not been reached, the process proceeds to STEP 210, the speed holding flag is set to "1" again, and the current drive rotational speed of the brushless motor 6 is held by the inverter control unit 112. . At this time, since the operation of keeping the speed of the brushless motor 6 constant is performed in the section 3 shown in FIG. 3, the regenerative energy stored in the regenerative absorption unit 27 is consumed by the power supply circuit 28 and the inverter control unit 112. Due to this, the voltage of the regenerative absorption part 27 is gradually decreased.

  Further, when it is detected in STEP 202 shown in FIG. 4 that the voltage of the regenerative absorption unit 27 has decreased to the intermediate value V2 or less as time passes, the process proceeds to STEP 203, and the speed holding flag is cleared to “0”. In STEP 204, a command is output to reduce the rotational speed of the brushless motor 6.

  By this command, the operation in the section 4 shown in FIG. 3 is started. That is, the inverter control unit 112 controls the brushless motor 6 to decelerate, returns to STEP 101 again in FIG. 4, and performs the same processing as in section 2 until the voltage of the regenerative absorption unit 27 reaches the upper limit value V1 due to the deceleration of the brushless motor 6. Is done.

  When the voltage of the regenerative absorption unit 27 reaches the upper limit value V1 again with the passage of time, the operation proceeds from the section 4 to the section 5 in FIG. The rotational speed of the brushless motor 6 is maintained until the voltage drops to the intermediate value V2.

  When the voltage of the regenerative absorption unit 27 is lowered to the intermediate value V1 by the above control, the operation of decreasing the rotation speed of the brushless motor 6 is started again. That is, the operation proceeds to the operation in the section 6 shown in FIG.

  In section 6, the brushless motor 6 is decelerated by the same control as in section 2 described above, and finally the command rotational speed (0 r / s, that is, “stop” in this embodiment) is reached.

  At this time, in STEP 101 shown in FIG. 4, the brushless motor 6 does not need to be decelerated. Therefore, the speed holding flag is cleared to “0” in STEP 301, and the motor is driven at the command rotation speed (0 r / s) in STEP 302.

  Therefore, in the timing chart of FIG. 3, when the brushless motor 6 is decelerating, the voltage of the regenerative absorption unit 27 rises, but after reaching the command rotational speed (0 r / s), the power supply circuit 28 and the power supply The regenerative energy accumulated in the regenerative absorption unit 27 by the inverter control unit 112 via the circuit 28 is consumed, and is reduced to a voltage (140 V) obtained by rectifying and smoothing the AC power supply and stabilized.

  Thus, when regeneration occurs due to the deceleration of the brushless motor 6, the regeneration energy is absorbed by the regeneration absorber 27, so that the inverter can be prevented from being destroyed by regeneration, and the voltage of the regeneration absorber 27 is equal to or higher than the upper limit value V1. When this occurs, the deceleration of the brushless motor 6 is stopped, and the consumption of the regenerative energy absorbed by the regenerative absorption unit 27 is urged. Therefore, it is not necessary to use a capacitor having a larger electrostatic capacity than necessary for the regenerative absorption portion 27, and the degree of freedom in design is increased.

  In the first embodiment, a case has been described in which the command rotational speed of the brushless motor 6 by the rotational speed setting means 31 for commanding the rotational speed is changed to 0 r / s, that is, a stop command. The same control can be used to reduce the speed to a rotational speed higher than / s (stop), that is, to a predetermined low-speed rotational speed.

  The upper limit value V1 and the intermediate value V2 are values set in accordance with the ratings of the inverter 5, the regenerative absorption unit 27, the brushless motor 6, and the like. In particular, the intermediate value V2 is the brushless motor 6 or the motor driving device. It can also be set according to the characteristics. In other words, if the characteristic allows significant deceleration in a short time, the difference between the upper limit value V1 and the intermediate value V2 can be set small. Conversely, if the characteristic is slow deceleration, the upper limit value V1. The intermediate value V2 may be appropriately secured.

  As described above, in the first embodiment, the regeneration that occurs when the rotational speed of the brushless motor 6 is decelerated is suppressed, and the failure of the device due to this is avoided to improve the reliability of the motor drive device. In addition, the regenerative energy consuming circuit that is connected in parallel with the regenerative absorption unit 27 and consumes regenerative energy includes a power supply circuit 28 that supplies power to the inverter control unit 112. The accumulated energy can be kept low, and it is not necessary to add a new circuit as a regenerative energy consuming circuit, the number of parts can be greatly reduced, and further miniaturization and cost reduction can be achieved.

  Further, the smoothing capacitor constituting the rectifier circuit 2 may be a chip type with a maximum output of the inverter and a capacitance of 0.2 μF or less per 1 W, and the noise filter can be simplified in combination with the miniaturization of the circuit. In addition to suppressing the outflow of noise due to switching of the inverter and suppressing noise entering from the power outlet, the EMC performance can be improved.

  In addition, by using a rare earth magnet for the rotor of the brushless motor 6, the induced voltage constant of the brushless motor can be increased, and the regenerative energy generated can be increased, which is expected to have a very high effect on protection from equipment breakdown due to regeneration. It can be done.

  The compressor equipped with the brushless motor 6 is a reciprocating type having a large moment of inertia (inertia), uses a refrigerant of R600a, and the capacitor 4 of the rectifier circuit 2 has a small capacity. Even when the input voltage fluctuates greatly, it is not easily affected by the increase in vibration and noise due to the uneven rotation of the brushless motor 6, and is equivalent to the motor drive device using a large-capacity smoothing capacitor in the rectifier circuit 2. It is possible to provide a compact and low-cost compressor drive system with noise.

  In addition, by applying the motor drive device described above to a refrigerator, it is possible to avoid a failure of the device due to regeneration, to eliminate waste such as uncooling in the cabinet caused by this, and corruption of food, and a circuit. By downsizing, it is possible to increase the volume of the food storage section in the storage even with the same appearance, and it is possible to provide a refrigerator with high internal volume efficiency.

  As described above, the motor drive device of the present invention is stable without stopping even without a position detection sensor even when a voltage including a large ripple is input to the inverter by greatly reducing the capacity of the smoothing capacitor. In addition to being able to drive, the regeneration due to the deceleration of the brushless motor can be quickly absorbed to prevent the failure of the apparatus, and the size and cost can be reduced, and high reliability can be ensured. Therefore, the present invention can be widely applied to applications such as an AV device (particularly a small device) such as a device in which a motor is very small and it is difficult to attach a sensor, or a device in which a circuit is very small.

1 is a block diagram of a motor drive device according to Embodiment 1 of the present invention. Compressor sectional view of a motor drive device in Embodiment 1 of the present invention Operational Flowchart of Motor Drive Device in Embodiment 1 of the Present Invention Operation Timing Chart of Motor Drive Device in Embodiment 1 of the Present Invention 1 is a block diagram of a motor driving device showing a first prior art. Block diagram of motor driving device showing second prior art Block diagram of motor driving apparatus showing fourth prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier circuit 3 Rectifier diode 4 Smoothing capacitor 5 Inverter 6 Brushless motor 9 Compressor 13 Refrigerator 15 Refrigerant 25 Regenerative processing circuit 26 2nd rectifier circuit (2nd rectifier part)
27 Regenerative Absorption Unit 28 Power Supply Circuit 29 Regenerative Energy Consumption Circuit 30 Voltage Detection Unit 31 Rotation Speed Setting Unit 112 Inverter Control Unit

Claims (10)

  A rectifier circuit that performs full-wave rectification using an AC power supply as an input, an inverter that receives an output voltage of the rectifier circuit that has a large pulsation, a brushless motor that is driven by the inverter, an inverter control unit that controls the inverter, A brushless motor comprising: a regenerative absorption unit that absorbs and accumulates regenerative energy of the brushless motor; a second rectification unit that is connected in series to the input side of the regenerative absorption unit; and a voltage detection unit that detects a voltage of the regenerative absorption unit. When the rotational speed of the brushless motor is driven at a speed lower than the current rotational speed, the motor that reduces the rotational speed of the brushless motor so that the voltage of the regenerative absorption unit detected by the voltage detecting means is kept below a predetermined voltage level. Drive device.   When the voltage of the regenerative absorption part detected by the voltage detection means rises above a preset maximum voltage, the voltage of the regenerative absorption part is set to a predetermined voltage level. The motor drive device according to claim 1, wherein the current rotational speed of the brushless motor is maintained until the pressure decreases.   The motor drive device according to claim 1, wherein a regenerative energy consuming circuit that consumes the regenerative energy is provided in parallel with the regenerative absorption unit.   4. The motor drive device according to claim 1, wherein the regenerative energy consumption circuit is a power supply circuit that supplies power to the inverter control unit. 5.   The rectifier circuit is configured to include a rectifier diode and a smoothing capacitor, and the capacitance of the smoothing capacitor is a capacitance of 0.2 μF or less per maximum output of 1 W of the inverter. The motor drive device as described in any one.   The motor drive device according to claim 5, wherein a capacitance of a capacitor constituting the regenerative absorption unit is set larger than a capacitance of a smoothing capacitor constituting the rectifier circuit.   The motor drive device according to any one of claims 1 to 6, wherein a rare earth magnet is used as a permanent magnet of a rotor of the brushless motor.   The motor drive device according to any one of claims 1 to 7, wherein the brushless motor is used for driving a compressor constituting a refrigerating and air-conditioning system, and the compressor has a reciprocating configuration.   The motor driving apparatus according to claim 8, wherein R600a is used as a refrigerant of the refrigeration air conditioning system.   A storage device comprising the motor driving device according to any one of claims 1 to 9.

Images