JP2008043013A - Motor driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor driving device capable of satisfying restriction on harmonics by reducing harmonics components of a current waveform of a single phase AC input without using a large-capacity reactor. <P>SOLUTION: The driving device includes a mean voltage acquiring means for acquiring a mean voltage between busbars; and a control means 118 for controlling an inverter 104 by using the mean voltage acquired in the mean voltage acquiring means and the position of a motor 105 detected by a position detecting means 114, and deciding a voltage to be applied to the motor 105. With this configuration, the voltage to be applied to the motor 105 substantially synchronizes with the voltage waveform of a single phase AC power supply 101, and the current waveform of the single phase AC power supply 101 can be improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a driving method and an apparatus for a motor serving as a driving source for a compressor or a blower provided in an air conditioner, a refrigerator, or the like, and a drum (washing tub) of a washing machine.

  Conventionally, as a conventional technique in this type of motor drive device, a single-phase AC power source is rectified to DC including a ripple component by a rectifier circuit in which diodes are bridge-connected, and the ripple component is included using a smoothing capacitor having a large capacity. A control device that smoothes the voltage and stably drives the motor is known.

  Also, as a different conventional technique, a method for improving the input current waveform from a single-phase AC power supply to the rectifier circuit has been proposed in order to reduce the size and cost of the motor drive device (see, for example, Patent Document 1). .

  FIG. 10 is a block diagram of a conventional motor driving apparatus that does not use a smoothing capacitor.

  In FIG. 10, an AC power source 1 is converted into DC power having pulsation by a rectifier diode 2 and input to an inverter 3. The inverter 3 converts the rectified DC power into AC power and applies a desired voltage to the brushless motor 4.

  The inverter control unit 5 includes a dq conversion unit 6, a d-axis PI controller 7, a q-axis PI controller 8, and a PWM generation unit 9, and includes an input voltage to the inverter 3, a motor current flowing through the brushless motor 4, and When a motor current command value indicating a value to be supplied to the brushless motor 4 is input and the input voltage value to the inverter 3 is smaller than the voltage value to be applied, the voltage phase of the applied voltage to the brushless motor 4 is maintained. The inverter 3 is controlled.

Thereby, even when the DC side voltage of the inverter 3 is low, the voltage is continuously applied without stopping the voltage application to the brushless motor 4, and stable even when a large pulsating voltage is input to the inverter 3. By realizing the drive, the motor drive device is miniaturized.
Japanese Patent Laid-Open No. 2005-20986

  However, since the former prior art uses a capacitor with a large capacity for smoothing the waveform, the input to the rectifier circuit flows only near the peak of the voltage.

  For this reason, harmonic regulations cannot be satisfied, and a large capacity reactor is used. Such a reactor has a problem that both size and weight are large, leading to cost increase.

  In the latter prior art, since there is no capacitor with a large smoothing capacity, current does not flow only near the peak of the single-phase AC voltage, but the input voltage to the motor is controlled to be constant. Therefore, in a section where the voltage of the single-phase AC input is lower than the voltage to be applied to the motor, the current waveform contains harmonic components in an attempt to keep the current flowing due to the capacity of the LC in the circuit. There was a problem that the waveform was greatly distorted.

  As a result, the distortion of the current waveform affects other devices having the same power supply as the device equipped with the motor driving device. For example, when the other device is a lighting fixture, the illumination is temporarily dark. As the number of devices equipped with the motor driving device increases, the influence on the lead-in wire power source (single-phase AC power source) drawn from the utility pole to the house increases.

  The present invention solves the above-described conventional problems, and provides a motor drive device that satisfies the harmonic regulation by reducing the harmonic component of the current waveform of the single-phase AC input without using a large-capacity reactor. For the purpose.

  In order to solve the above-described conventional problems, the motor driving apparatus of the present invention uses a voltage / current obtained by rectifying a single-phase AC power source by a rectifier circuit as an input directly to an inverter, and calculates an average voltage applied to the motor. The average voltage acquired by the voltage acquisition means is used.

  As a result, the voltage waveform applied to the motor is substantially synchronized with the voltage waveform of the single-phase AC power supply and does not include harmonic components, so that the current waveform of the single-phase AC power supply (voltage applied to the motor) is It will be improved.

  The motor drive device of the present invention can improve the current waveform of a single-phase AC input with a simple configuration without using a large-capacity reactor, etc., and the influence on the single-phase AC power source due to harmonic components is mitigated, and it is compact -A low-cost motor drive device can be provided.

  The invention according to claim 1 is a single-phase AC power source, a rectifier circuit that rectifies and converts a current input from the single-phase AC power source into a direct current, and outputs a direct current output from the rectifier circuit. Inverter, a motor driven by the inverter, an average voltage acquisition means for acquiring an average voltage between DC buses of the rectifier circuit, a position detection means for detecting the position of a rotor constituting the motor, Control means for determining an applied voltage to the motor using the average voltage acquired by the average voltage acquiring means and the detected position signal detected by the position detecting means as input signals, and the determined applied voltage is supplied to the motor The inverter is controlled to be supplied.

  By adopting such a configuration, the voltage applied to the motor is set assuming that the voltage in a predetermined range (for example, a half-wave section in the power supply waveform) is constant, and the duty is continuously varied according to the conventional voltage fluctuation. Unlike control, duty (rate) setting (calculation processing) when forming an applied voltage to the motor is facilitated, and the applied voltage can be supplied quickly.

  According to a second aspect of the present invention, the average voltage acquisition unit includes: a voltage detection unit that detects the voltage of the DC bus; and an average voltage calculation that calculates and outputs an average voltage by calculating the voltage detected by the voltage detection unit. And the position detection means detects the position of the rotor from the current detected by the current detection means and the voltage detected by the voltage detection means. The motor phase calculation means is configured.

  With this configuration, the average voltage can be set by calculation processing based on the detection value of the voltage detection means necessary for accurately estimating the motor phase, and the voltage detection means detects the average voltage. Therefore, it is possible to reduce the number of components and improve the position detection accuracy at low cost.

  According to a third aspect of the present invention, a duty is determined by arithmetic processing based on the determined applied voltage value and the average voltage value acquired by the average voltage acquisition means, and the inverter is driven based on the duty. Is.

  With this configuration, since the motor is supplied with a constant duty ratio, the voltage waveform applied to the motor is substantially synchronized with the voltage waveform of the single-phase AC power supply, and as a result, the voltage waveform applied to the motor. Therefore, the current waveform of the single-phase AC power supply is improved, and a miniaturized and low-cost motor drive device in which the harmonic component of the current waveform is improved can be provided.

  Further, along with the improvement of the current waveform, adverse effects on the equipment due to harmonic components are suppressed, and sudden voltage fluctuations of the single-phase AC power supply during startup and restart of the motor are mitigated.

  According to a fourth aspect of the present invention, the average voltage acquisition, the rotor position detection, and the arithmetic processing for determining the applied voltage in predetermined time units using these are performed.

  As a result, it is not necessary to change and control the duty for the predetermined time, and there is no load of calculation processing for control. This leads to simplification of the control program, shortens the calculation processing time for controlling the rotational speed of the motor, and allows the motor to be driven quickly.

  According to a fifth aspect of the present invention, the voltage acquisition time acquired by the voltage acquisition means for calculating the average voltage is a common multiple of the half-wave time at the power supply frequency.

  As a result, the average voltage can be calculated and set accurately, and by minimizing the common multiple, the voltage applied to the motor can be supplied quickly, and there is little distortion of the current waveform with respect to the power supply voltage. The motor can be driven.

  In a sixth aspect of the present invention, a small-capacitance capacitor is connected between the DC buses of the rectifier circuit.

  With this configuration, it is possible to store and use regenerative energy from the motor when the voltage drops, and as a result, it is possible to generate a larger torque for starting the motor.

  According to a seventh aspect of the present invention, the motor is used for driving a compressor constituting a refrigeration cycle.

  As a result, in the case of a compressor driving motor having a large moment of inertia, it is less affected by torque fluctuations due to voltage fluctuations and can be driven more stably.

  In the invention described in claim 8, the compressor is a reciprocating compressor, and as a result, the moment of inertia becomes larger than that of a scroll compressor, a rotary compressor, or the like, and further stable driving is achieved. It becomes possible.

  The invention according to claim 9 is the one in which the compressor is provided in a refrigeration cycle that constitutes a refrigerator. Thus, even in a refrigerator in which harmonic regulation is severe, harmonic regulation is achieved at a small size and at low cost. Can be satisfied.

  Moreover, since it is a small motor drive device, a refrigerator with a high internal volume ratio can be obtained, and a refrigerator that is easy to use can be obtained with the same external dimensions as the conventional one, with a larger storage capacity.

  In a tenth aspect of the present invention, the motor is used for driving a fan constituting a blower.

  By adopting such a configuration, as the motor driving device is reduced in size and weight, the blower itself can be further reduced in size and weight as compared with the conventional blower, and a highly portable blower can be provided.

  According to an eleventh aspect of the present invention, the motor is used for rotationally driving a drum of an electric washing machine for washing dirt or the like of clothes.

  This makes it possible to increase the volume ratio of the drum of the washing machine because a miniaturized motor control device is used, and increase the capacity of the washing and dewatering tub with the same external dimensions as a conventional electric washing machine. Can be achieved.

  The invention according to claim 12 is used for rotational driving of a drum of an electric dryer for drying wet clothes and the like, and by using such a motor control device that is downsized, The volume ratio of the drum of the dryer can be increased, and a large drum capacity can be achieved with the same external dimensions as those of a conventional electric dryer.

  In the invention according to claim 13, the motor is used for driving a fan of an electric vacuum cleaner that sucks in garbage such as floors, and thus, a motor control device that is reduced in size and weight is used. The machine body can be made smaller and lighter than conventional vacuum cleaners, and a vacuum cleaner that is highly portable and easy for users to handle can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments.

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

  In FIG. 1, a single-phase AC power source 101 is a commercial power source, which is 100 VAC, 50 Hz, or 60 Hz in Japan and is connected to a rectifier circuit 102.

  As is well known, the rectifier circuit 102 is configured by a circuit in which four diodes are bridge-connected.

  The smoothing capacitor 103 is supplied with a voltage that has been full-wave rectified by the rectifier circuit 102. The capacitor 103 has a capacitance of 0.2 μF / W or less.

  This type of smoothing capacitor is generally a smoothing capacitor based on the output capacity (W or VA) of the inverter 104 or the input capacity (W or VA) of the entire drive device, or the ripple content or ripple current of the DC voltage. The capacitance of the capacitor is determined from the characteristics of the ripple current resistance.

  In consideration of these conditions, a capacity of about 2 to 4 μF / W is generally secured. 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 103. That is, in the case of an output capacity of 200 W, a capacitor of 40 μF or less is used.

  As the type of the capacitor 103, a multilayer ceramic capacitor, a film capacitor, or the like can be used. In particular, a multilayer ceramic capacitor has recently been able to realize a high-capacitance and large-capacity capacitor on a chip, and the device is very small. There is an advantage that can be made.

  In the first embodiment, a multilayer ceramic capacitor having a capacitance of 1 μF is used for the capacitor 103 as described above.

  Inverter 104 is a six-circuit three-phase bridge connected to a set of diodes connected in the opposite direction to the switching element. An IGBT, a bipolar transistor, an FET, or the like can be used as the switching element. The first embodiment will be described as an inverter by PWM (Plus Width Modulation) control.

  A brushless DC motor (hereinafter simply referred to as a motor) 105 is driven by the three-phase output of the inverter 104. The stator of the motor 105 is provided with a three-phase star-connected winding, and this winding method may be concentrated winding or distributed winding. The rotor 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.

  When using a permanent magnet, if a rare earth magnet is used and the weight of the magnet used is the same as that of a ferrite magnet, the motor efficiency can be improved and the performance equivalent to that of a motor using a ferrite magnet can be obtained. In the case of a motor, the weight of the magnet can be reduced, so that the weight of the motor can be reduced.

  The compression element 106 is connected to the shaft of the rotor that constitutes the motor 105, and sucks, compresses and discharges the refrigerant gas. The motor 105 and the compression element 106 are accommodated in the same sealed container 107 to constitute a reciprocating compressor 108. The compressor 108 is a rotary type or a scroll type depending on the equipment to be mounted. The specific configuration of the compressor 108 will be described later with reference to FIG.

  The compressor 108 forms a refrigeration air-conditioning system (refrigeration cycle) in which the refrigerant gas compressed and discharged here returns to the suction of the compressor 108 through the condenser 109, the decompressor 110, and the evaporator 111. Since heat is dissipated in 109 and heat is absorbed in the evaporator 111, cooling and heating can be performed.

  If necessary, a fan or the like may be added to the condenser 109 or the evaporator 111 to further promote heat exchange.

  In the first embodiment, a refrigerator is taken as an example of a device equipped with a refrigeration air conditioning system, and the interior 112 is cooled by the evaporator 111.

  The voltage detection means 113 detects the voltage between the DC buses V1 and V2 of the rectifier circuit 102 and uses it as an input to the position detection means 114 and the average voltage calculation means 115.

  The position detection means 114 includes a current detection means 116 and a motor phase calculation means 117, and detects (calculation processing) the position (rotation angle) of the rotor that constitutes the motor 105 based on these signals. As an input to the control means 118.

  The current detection means 116 detects the current flowing through the motor 105 and inputs the detected current value as a signal to the motor phase calculation means 117. Further, as the current detection means 116, a current sensor, a shunt resistor or the like can be used. The shunt resistor is particularly small and low cost, and is highly feasible.

  Further, the motor phase calculation means 117 inputs (signal) the current value of the motor 105 that is the output of the current detection means 116 and the voltage value between the DC buses V1 and V2 of the rectifier circuit 102 that is the output of the voltage detection means 113. The position (rotation angle) of the rotor of the motor 105 is detected by calculating these signals. The detected position information is used as an input (signal) to the control means 118.

  The average voltage calculation means 115 receives the voltage value between the DC buses V1 and V2 of the rectifier circuit 102 that is the output of the voltage detection means 113 as an input, and is described as the previous set time (in the first embodiment, the past 50 milliseconds). The average of the voltages input to the control means 118 is calculated and used as an input (signal) to the control means 118.

  In the first embodiment, since the target period (previous set time) for calculating the average voltage is set to the past 50 milliseconds, the common multiple of the half-wave time at the domestic power supply frequencies of 50 Hz and 60 Hz is obtained. A stable average voltage is calculated regardless of whether the frequency of the single-phase AC power supply 101 is 50 Hz or 60 Hz. Since the single-phase AC power supply 101 is a periodic function, the average voltage is as follows.

  With this formula, the average voltage Vav is about 0.9 times the effective value Ve. Therefore, if it is an effective value of AC 100V, the average voltage is about 90V.

  The control means 118 receives the position information of the motor 105, which is the output of the position detection means 114, and determines the applied voltage (voltage for obtaining a predetermined torque of the motor) of the motor 105. Then, the PWM duty width is determined from the determined applied voltage and the average voltage calculated by the average voltage calculation means 115, and the inverter 104 is driven.

  As described above, the position of the motor 105 is detected using the voltage between the DC buses V1 and V2 detected by the voltage detection means 113 instead of the average voltage, thereby calculating the duty while accurately detecting the position of the motor 105. An average voltage can be used to improve the harmonic component.

  In addition, a slight deviation between the position of the motor 105 (rotor) and the actual position of the motor (rotor) by the position detection means 114 of the motor 105, a weak magnetic flux control for high torque operation, or the like is performed. Even if the energy from the motor 105 is returned, the capacitor 103 having a capacitance of 0.2 μF / W is selected, so that a steep voltage change can be absorbed and the motor 105 can be driven using the absorbed energy. it can.

  Next, the configuration of the compressor 108 will be described with reference to FIG. FIG. 2 shows a cross-sectional view of the compressor in the first embodiment.

  In FIG. 2, oil 119 is stored in an airtight container 107 of the compressor 108 and a refrigerant 120 of R600a is sealed, and the motor 105 mainly composed of a stator 121 and a rotor 122 is driven by this. The compression element 106 is elastically supported by a spring or the like, so that vibration due to rotation of the motor 105 is difficult to propagate outside the compressor.

  The compression element 106 includes a cylinder 127 that supports a main shaft portion 123 of a crankshaft 125 including a main shaft portion 123 to which a rotor 122 is fixed and an eccentric shaft portion 124, and has a compression chamber 126. And a connecting means 129 for connecting the eccentric shaft portion 124 and the piston 128 to form a reciprocating type compression mechanism.

  Therefore, in the first embodiment, even when the input voltage of the inverter includes a large pulsation, the vibration due to the pulsation and the noise accompanying the vibration are difficult to leak out of the compressor due to the characteristics and structure of the reciprocating compressor having a large inertia. It has become.

  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 becomes larger. Therefore, since the motor inertia is increased, even if the capacitor 103 has a very small capacity, even if the inverter input voltage includes a large pulsation, it is less susceptible to vibration and noise.

  The voltage detection means 113, the position detection means 114 (current detection means 116, motor phase calculation means 117), the average voltage calculation means 115, and the control means 118 have a microcomputer as well known because of the calculation processing of various signals. It is composed of a central integrated circuit (LSI).

  The operation and action of the motor driving apparatus configured as described above will be described below.

  First, the case where control is performed using the voltages of the DC buses V1 and V2 without using the average voltage as in the description of the prior art will be described with reference to FIG. 1, FIG. 3, FIG. 4, FIG. .

  FIG. 3 is a waveform diagram showing a part (half wave) of the transition of the DC bus voltage in the motor driving apparatus according to the first embodiment. FIG. 4 is a graph showing a part (half wave) of the average voltage transition for each carrier cycle applied to the motor when the DC bus voltage value by the conventional control is used. FIG. 5 is a graph showing a part (half wave) of the transition of the PWM duty ratio in each carrier cycle when the DC bus voltage value by the conventional control is used. FIG. 6 is a waveform diagram showing a part (half wave) of a transition of current flowing in the motor when a DC bus voltage value by conventional control is used.

  In the waveform diagrams and graphs, one cycle of the waveform is described as 20 milliseconds for convenience.

  Based on the position information of the motor 105 detected by the position detection unit 114, the control unit 118 determines a voltage to be applied to the motor 105. Here, the applied voltage of the motor 105 is set to 64 V for convenience, and the description will proceed.

  At this time, in the conventional control, since the PWM duty is calculated using the voltage between the DC buses V1 and V2, in the period from T1 milliseconds to T2 milliseconds where the DC bus voltage is 64 V or more in FIG. As shown in FIG. 5 from T1 millisecond to T2 millisecond, the duty ratio is controlled in inverse proportion to the voltage rise, so that the average voltage for each carrier period in the interval from T1 millisecond to T2 millisecond is shown in FIG. As shown, the control is performed to be 64V.

  That is, in the conventional control, the voltage applied to the motor 105 for each carrier cycle is set by controlling the duty ratio.

  On the other hand, the voltage between the DC buses V1 and V2 is to be applied to the motor 105 to the maximum in the interval from 0 milliseconds to T1 milliseconds, and from T2 milliseconds to 10 milliseconds, where the voltage between the DC buses V1 and V2 is 64 V or less. Therefore, the duty ratio is 100% as shown in the same section of FIG. Therefore, the voltage applied to the motor 105 is equal to the voltage (waveform) of the DC bus as shown in FIG.

  As a result, as shown in FIG. 6, the current from T1 milliseconds to T2 milliseconds is almost constant, and since the voltage decreases from T2 milliseconds to 10 milliseconds, the current cannot flow and the current value decreases. .

  In addition, even when the voltage is 0 V, the current continues to flow due to the inductor component of the single-phase AC power supply 101 and the voltage rises from 0 V corresponding to the interval from 0 ms to T 1 in FIG. In the section, a current that continues to flow at the falling portion flows, the current waveform is sharp as shown by P in FIG. 6, and includes a harmonic component.

  Next, the control according to the first embodiment, that is, the case where the control means 118 calculates the applied voltage to the motor 105 using the average voltage between the DC buses V1 and V2 calculated by the average voltage calculation means 115. 1, FIG. 3, FIG. 4, FIG. 7, FIG. 8, and FIG.

  In the first embodiment, a case where the power supply frequency is 50 Hz and the time for calculating the average voltage is 50 milliseconds as described above will be described. Therefore, assuming that the power supply cycle is stable, the average voltages of 50 milliseconds and 10 milliseconds are equal, and therefore, in the following description, description will be made with reference to a section of 10 milliseconds for convenience.

  FIG. 7 is a graph showing a part (half wave) of the transition of the PWM duty ratio for each carrier cycle when the average voltage value is used in the first embodiment. FIG. 8 is a graph showing a part (half wave) of the average voltage transition for each carrier cycle applied to the motor when the average voltage value in the first embodiment is used. FIG. 9 is a waveform diagram showing a part (half wave) of a transition of current flowing in the motor when the average voltage value in the first embodiment is used.

  First, the average voltage calculated by the average voltage calculation means 115 is about 90 V from the above-described equation 1, and the duty required to output 64 V to the motor 105 is calculated to be about 71%. When the DC bus voltage is used for the duty calculation as in the prior art, the duty (rate) fluctuates as shown in FIG. 5, but in the first embodiment, the average voltage is used for the calculation. As shown in FIG. 7, the duty (rate) in the carrier cycle is constant over the entire period from 0 milliseconds to 10 milliseconds.

  As a result, the average voltage transition for each carrier cycle applied to the motor 105 is about 0.71 times the transition value of the DC bus voltage (output voltage of the rectifier circuit 102) shown in FIG. 3, as shown in FIG. This substantially coincides with the voltage transition of the single-phase AC power supply 101 on the input side of the rectifier circuit 102.

  As a result, the voltage applied to the motor 105 changes in a sine wave shape, and the change in the total current flowing in the motor 105 also becomes a sine wave shape as shown in FIG. 9, so that the harmonic component is greatly improved.

  That is, conventionally, in order to make the applied voltage to the motor 105 constant, the bus voltage and the duty in one carrier cycle are captured as change numerical values, and both are changed with the passage of time. In this example, in order to synchronize (change) the voltage applied to the motor 105 with the AC power supply (inter-bus voltage), the average voltage and the duty of the inter-bus voltage are controlled to be constant. Various arithmetic processes and output processes are performed by a microcomputer program configuration.

  Such control can be performed so that harmonics are not generated even in the case of a low current value, such as when the load is light and the motor 105 is operated at a low speed. Suitable for strict refrigerator control.

  The applied voltage is determined each time according to the position of the rotor detected by the position detecting means 114, and is not necessarily fixed at a constant value (64V).

  As described above, in the first embodiment, the single-phase AC power supply 101, the rectifier circuit 102 that rectifies the current input from the single-phase AC power supply 101, converts it to DC, and outputs it, and outputs from the rectifier circuit 102. Inverter 104 having DC input as input, motor 105 driven by inverter 104, voltage detection means 113 and average voltage calculation means 115 are provided, and an average voltage between DC buses V1 and V2 of rectifier circuit 102 is obtained. Using the average voltage acquisition means, the position detection means 114 for detecting the position of the motor 105, the average voltage acquired by the average voltage calculation means 115 and the position of the motor 105 detected by the position detection means 114. By forming a control means 118 that controls and determines the voltage applied to the motor 105, the voltage applied to the motor 105 is formed. Saishi by the duty (the ratio) is constant, is to supply power to the motor 105 based on the duty.

  As a result, the voltage applied to the motor 105 is substantially synchronized with the voltage waveform of the single-phase AC power supply 101, and the current waveform of the single-phase AC power supply 101 is improved. A motor driving apparatus can be provided.

  Further, the voltage detection means 113 for detecting the voltages of the DC buses V1 and V2 and the voltage detected by the voltage detection means 113 are used to calculate the average voltage, and the average voltage calculation means 115 for outputting the voltage constitutes the voltage acquisition means. The position detection unit 114 includes a current detection unit 116 that acquires the current of the motor 105, and a motor phase calculation that detects the position of the motor 105 from the current detected by the current detection unit 116 and the voltage detected by the voltage detection unit 113. With the configuration of the means 117, the voltage detection necessary for accurately estimating the motor phase and the voltage detection for detecting the average voltage can be detected by the single voltage detection means 113, so that the number of parts can be reduced. As a result, the position detection accuracy can be improved at low cost.

  Furthermore, by connecting a small-capacitance capacitor 103 between the DC buses of the rectifier circuit 102, the regenerative energy from the motor 105 is stored and used when the voltage drops, and a larger torque can be generated.

  In the case of the motor 105 that drives the compressor 108, even if torque fluctuation occurs due to voltage fluctuation, the influence on the motor 105 is small because the moment of inertia of the compressor 108 is large. More stable driving is possible.

  Furthermore, since the compressor 108 is a reciprocating type compressor, the moment of inertia is larger than that of a scroll type compressor, a rotary type compressor, or the like, and a more stable drive is possible.

  In addition, since the refrigerant compressed by the compressor 108 is R600a, the refrigeration capacity is lower than that of R134a generally used in refrigerators and the like. Need to be larger. Such a configuration further increases the moment of inertia, so that a very stable operation can be performed.

  Furthermore, since the motor drive device changes the voltage waveform applied to the motor 105 in a sine wave shape, the transition of the total current flowing in the motor 105 also becomes a sine wave shape with improved harmonic components.

  Therefore, the compressor 108 provided with the motor drive device is provided in a refrigeration air conditioning system (refrigeration cycle) configured with a condenser 109, a decompressor 110, an evaporator 111, and the like, and this refrigeration air conditioning system is employed in a refrigerator. Thus, a refrigerator that satisfies the harmonic regulations can be obtained. Moreover, since the motor driving device is small, the refrigerator volume ratio can be increased, and a convenient refrigerator with a larger storage capacity and the same outer dimensions as the conventional one can be provided.

  In addition, by applying the refrigeration and air conditioning system to an air conditioner, the air conditioner can be downsized, and an air conditioner with improved harmonics can be configured at low cost. Therefore, the freedom degree of the installation space in an air conditioner can be raised.

  The motor drive device can be used for applications other than the refrigerating and air-conditioning system, and has effects specific to various devices applied.

  Hereinafter, several devices to which the motor drive device is applied will be described as an example.

  When the motor 105 is used for driving a fan of a blower, the blower itself can be made smaller and lighter than a conventional blower because it is a motor drive device that is smaller and lighter. A high air blower can be provided.

  In addition, when the motor 105 is used for rotational driving of a drum (washing and dewatering tub) of an electric washing machine for washing dirt of clothes, etc., the drum of the washing machine is attributed to the miniaturized motor driving device. The volume ratio can be increased, and the capacity of the washing and dewatering tub can be increased with the same external dimensions as those of the conventional electric washing machine.

  Similarly, when the motor 105 is used for rotationally driving a drying drum of an electric dryer that dries wet clothes and the like, the drying drum volume ratio of the dryer is attributed to the miniaturized motor driving device. It becomes possible to increase the capacity of the drying drum with the same outer dimensions as those of the conventional electric dryer.

  Further, when the motor 105 is used for driving a fan of an electric vacuum cleaner that sucks in dust such as floors, the vacuum cleaner main body is replaced with a conventional vacuum cleaner due to the fact that the motor drive device is reduced in size and weight. As a result, it is possible to provide a vacuum cleaner that is easy to use and easy to handle for the user.

  As described above, the motor driving device according to the present invention can suppress harmonics in a small size and at low cost, so that it can be used for AV equipment (particularly, small equipment) in addition to a refrigerating and air conditioning system such as an air conditioner. The present invention can also be applied to applications such as when it is desired to miniaturize a device or circuit that has a very small motor and is difficult to attach a sensor.

1 is a block diagram of a motor drive device according to Embodiment 1 of the present invention. Sectional drawing of the compressor driven by the drive device in Embodiment 1 The wave form diagram which shows a part (half wave) of transition of the DC bus voltage in the motor drive apparatus in the first embodiment The graph which shows a part (half wave) of the average voltage transition for every carrier period applied to the motor when the DC bus voltage value by the conventional control is used The graph which shows a part (half wave) transition of the PWM duty factor for every carrier period when the DC bus voltage value by the conventional control is used Waveform diagram showing a part (half wave) of the current transition through the motor when using the DC bus voltage value under conventional control The graph which shows a part (half wave) transition of the PWM duty factor for every carrier period when using the average voltage value in Embodiment 1 of this invention The graph which shows a part (half wave) of average voltage transition for every carrier period applied to the motor at the time of using the average voltage value in Embodiment 1 Waveform diagram showing a part (half wave) of a current transition flowing in the motor when using the average voltage value in the first embodiment Block diagram of a motor driving device in the prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Single phase alternating current power supply 102 Rectifier circuit 103 Capacitor 104 Inverter 105 Motor 106 Compression element 107 Sealed container 108 Compressor 109 Condenser 110 Decompressor 111 Evaporator 112 Inside 113 Voltage detection means 114 Position detection means 115 Average voltage calculation means 116 Current Detection means 117 Motor phase calculation means 118 Control means 119 Oil 120 Refrigerant 121 Stator 122 Rotor 123 Main shaft part 124 Eccentric shaft part 125 Crankshaft 126 Compression chamber 127 Cylinder 128 Piston 129 Connection means

Claims (13)

  A single-phase AC power source, a rectifier circuit that rectifies and converts a current input from the single-phase AC power source into a direct current, and outputs a direct current output from the rectifier circuit; and an inverter driven by the inverter Motor, average voltage acquisition means for acquiring an average voltage between DC buses of the rectifier circuit, position detection means for detecting the position of a rotor constituting the motor, and average acquired by the average voltage acquisition means Control means for determining an applied voltage to the motor by using a voltage and a detected position signal detected by the position detecting means as an input signal, and controlling the inverter so that the determined applied voltage is supplied to the motor A motor drive device.   The average voltage acquisition means comprises voltage detection means for detecting the voltage of the DC bus, and average voltage calculation means for calculating and outputting an average voltage by calculating the voltage detected by the voltage detection means, and the position detection means Is constituted by current detection means for acquiring the current of the motor, and motor phase calculation means for detecting the position of the rotor from the current detected by the current detection means and the voltage detected by the voltage detection means. Item 2. A motor driving device according to Item 1.   3. The motor driving device according to claim 1, wherein a duty is calculated based on the determined applied voltage value and the average voltage value acquired by the average voltage acquisition unit, and the inverter is driven based on the duty.   4. The motor driving apparatus according to claim 1, wherein the average voltage acquisition, the rotor position detection, and the calculation process for determining the applied voltage in a predetermined time unit are performed using the average voltage acquisition. 5. .   5. The motor driving apparatus according to claim 1, wherein the voltage acquisition time acquired by the voltage acquisition unit to calculate an average voltage is a common multiple of a half-wave time at a power supply frequency. 6.   The motor drive device according to any one of claims 1 to 5, wherein a small-capacitance capacitor is connected between the DC buses of the rectifier circuit.   The motor driving device according to any one of claims 1 to 6, wherein the motor is used for driving a compressor constituting a refrigeration cycle.   The motor driving apparatus according to claim 7, wherein the compressor is a reciprocating compressor.   The motor driving device according to claim 7 or 8, wherein the compressor is provided in a refrigeration cycle constituting a refrigerator.   The motor driving device according to any one of claims 1 to 6, wherein the motor is used for driving a fan constituting a blower.   The motor driving device according to any one of claims 1 to 6, wherein the motor is used for rotationally driving a drum of an electric washing machine for washing dirt or the like of clothes.   The motor drive device according to any one of claims 1 to 6, wherein the motor is used for rotationally driving a drum of an electric dryer for drying wet clothes and the like.   The motor driving device according to any one of claims 1 to 6, wherein the motor is used for driving a fan of an electric vacuum cleaner that sucks dust such as floor.

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