JP2005090466A - Compressor drive mechanism and refrigerator using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reciprocating compressor drive mechanism free of starting failure. <P>SOLUTION: With a line connecting the compression top dead center of a piston 107 in a reciprocating compressor 15 and the bottom dead center thereof as a criterion, a position of displacing θinit 45° or so to the rotating direction is an optimal starting initial position. As starting motor constants for displacing a rotor 117 to the starting initial position, a rotating initial position θinit, a starting acceleration ωinit, a starting d-axis current Idinit, and a starting q-axis current Iqinit are set. Before starting, a one-phase driving current is carried to a compressor motor 28 in accordance with the starting motor constants and the rotor 117 is made ready at the starting initial position. Then, when started from the starting initial position, the rotor 117 can be normally started from any starting position. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a compressor driving device that drives a compressor motor by an inverter circuit.

  Conventionally, a reciprocating compressor has been used as a drive source for a compressor of a refrigerator.

  As this type of compressor, a crank is extended from a crank pin integrated with a rotating shaft of a motor, and the crank and a piston accommodated in a cylinder chamber are connected via a ball joint mechanism. A ball integrally provided at the end of the crank, and a ball receiving seat provided on the piston for slidably holding the ball, and rotating the motor to cause the piston to retaliate in the cylinder chamber. A refrigerant | coolant is compressed (for example, refer patent document 1).

By the way, when controlling the motor of such a compressor, it is necessary to detect the position of the rotor of the motor. For this reason, if a position detecting element such as a Hall IC is used, the position of the rotor can be detected reliably, but the cost is increased. Therefore, in normal inverter control, since it is activated by two-phase energization, sensorless control is performed in which position detection can be performed by induced electric power generated by another phase that is not energized.
JP 2003-214343 A

  However, in vector control, the rotor position is detected by shunt resistance by energizing the three phases simultaneously, so that the motor rotor position can be accurately captured until the motor reaches a predetermined speed when the motor is started. Therefore, the speed control is started after the rotor reaches the predetermined speed at the time of activation.

  However, in a 6-slot, 4-pole brushless DC motor, there are two electrical control positions symmetrically within 180 ° in one rotation of the motor, so that there are two rotors at the next start-up depending on the stop position of the rotor. There is a problem that you don't know where to start from.

  Further, since the compressor performs the compression operation by the piston by making one rotation, the torque applied to the rotor always varies depending on the position during rotation. Therefore, in the case where the compressor is started in a state where there is a pressure difference between the suction port and the discharge port of the compressor, there is a problem that the start rarely fails.

  Therefore, the present invention provides a compressor drive device that does not fail to start in order to solve the above-described problems.

  The present invention includes a reciprocating compressor that is rotated by a three-phase brushless DC motor, a condenser, and a refrigeration cycle having at least an evaporator, and driving the compressor that cools the evaporator by compressing refrigerant by the compressor. In the apparatus, an inverter circuit that supplies a three-phase drive current to a stator winding of the brushless DC motor, a PWM circuit that supplies a PWM signal to the inverter circuit, and a drive current detection that detects the three-phase drive current And a d-axis current, which is a current component corresponding to the magnetic flux of the rotor of the brushless DC motor, and a current component corresponding to the torque of the brushless DC motor, based on the detected three-phase drive current Dq conversion means for converting into shaft current, and the converted d-axis current, q-axis current, and speed command signal inputted from outside A control means for outputting a reference q-axis current and a reference d-axis current; a voltage conversion means for converting the reference q-axis current and the reference d-axis current into a reference q-axis voltage and a reference d-axis voltage; Three-phase conversion means for converting the converted reference q-axis voltage and reference d-axis voltage into a three-phase voltage and outputting it to the PWM circuit, and a line connecting the position of the piston of the compressor and the compression top dead center and bottom dead center Initial pattern output means for rotationally moving the rotor of the brushless DC motor to an initial start position that is a position rotated from 40 ° to 50 ° as a reference; and an start means for starting the compressor from the initial start position. This is a compressor driving device.

  According to the present invention, by moving the rotor of the brushless DC motor to the initial start position at the start of the compressor, the compressor can be operated even when there is a pressure difference between the suction port and the discharge port of the compressor at the start by the sine wave inverter. It can be started and optimal refrigeration cycle control can be performed.

  As the starting initial position, a position rotated by 40 ° to 50 ° with respect to a line connecting the position of the piston of the compressor and the compression top dead center and the bottom dead center, particularly a position of 45 ° is preferable.

  The compressor driving device is preferably used in a refrigeration cycle of a refrigerator.

  The invention according to claim 1 includes a refrigeration cycle having at least a reciprocating compressor that is rotated by a three-phase brushless DC motor, a condenser, and an evaporator, and the refrigerant is compressed by the compressor to cool the evaporator. An inverter circuit for supplying a three-phase drive current to a stator winding of the brushless DC motor, a PWM circuit for supplying a PWM signal to the inverter circuit, and detecting the three-phase drive current A drive current detection means that performs the d-axis current that is a current component corresponding to the magnetic flux of the rotor of the brushless DC motor, and a current that corresponds to the torque of the brushless DC motor based on the detected three-phase drive current Dq conversion means for converting the component into q-axis current, and the converted d-axis current and q-axis current and the speed inputted from the outside. Control means for outputting a reference q-axis current and a reference d-axis current based on the command signal, and a voltage conversion means for converting the reference q-axis current and the reference d-axis current into a reference q-axis voltage and a reference d-axis voltage Three-phase conversion means for converting the converted reference q-axis voltage and reference d-axis voltage into a three-phase voltage and outputting the same to the PWM circuit, and the piston position, compression top dead center, and bottom dead center of the compressor. Initial pattern output means for rotationally moving the rotor of the brushless DC motor to an initial start position, which is a position rotated from 40 ° to 50 ° with respect to the connecting line, and start means for starting the compressor from the start initial position; And a compressor driving device.

  The invention according to claim 2 is the compressor drive device according to claim 1, wherein the brushless DC motor is a three-phase four-pole.

  The invention according to claim 3 is characterized in that the starting initial position is a position rotated by 45 ° with respect to a line connecting the position of the piston, a compression top dead center, and a bottom dead center. It is a drive device of a compressor.

  The invention according to claim 4 is the compressor drive device according to at least one of claims 1 to 3, wherein the refrigeration cycle is a refrigeration cycle of a refrigerator.

(Embodiment)
Hereinafter, the refrigerator 1 of one Embodiment of this invention is demonstrated.

(1) Structure of refrigerator 1 First, the structure of the refrigerator 1 is demonstrated based on FIG. 6 and FIG.

  FIG. 6 is a cross-sectional view of the refrigerator 1 showing the present embodiment, and FIG. 7 is a refrigeration cycle of the refrigerator 1.

  The cabinet of the refrigerator 1 is formed of a heat insulating box 9 and an inner box 8, and is partitioned into a refrigeration temperature zone 30 and a freezing temperature zone 31 by the heat insulating partition wall 2, and the cold air in both temperature zones 30, 31 is completely independent. Each cold air is not mixed.

  The inside of the refrigerated temperature zone 30 is partitioned into the refrigerated storage room 4 and the vegetable compartment 5 by the refrigeration partition plate 3, and the inside of the freezing temperature zone 31 is composed of the first freezer compartment 6 and the second freezer compartment 7, Has open / close doors 4a, 5a, 6a and 7a, respectively. The refrigerated storage room 4 is provided with a temperature sensor (hereinafter referred to as R sensor) 34 for detecting the internal temperature and a deodorizing device 35.

  A refrigeration room evaporator 10 and a refrigeration room cooling fan 11 are disposed on the back of the vegetable room 5, and the refrigeration room cooling fan 11 is arbitrarily operated by changing the temperature in the cabinet or opening and closing the door. The rear surface of the refrigerated storage chamber 4 serves as a cold air circulation path 18 for supplying cold air into the refrigerated temperature zone 30. A defrost heater 26 is disposed below the freezer evaporator 12.

  The freezer compartment evaporator 12 and the freezer compartment cooling fan 13 are disposed on the back walls of the first and second freezer compartments 6 and 7, and the first and second freezer compartments 6 and 7 are cooled by circulating cold air.

  As shown in FIG. 7, a compressor 15 and a condenser 21 constituting a refrigeration cycle are arranged in the machine room 14 below the back wall of the refrigerator 1. The combustible refrigerant discharged from the compressor 15 passes through the condenser 21. After passing, the refrigerant flow path is alternately switched by the refrigerant switching mechanism of the switching valve 22 so that the refrigeration mode and the refrigeration mode can be realized alternately.

  The refrigerating capillary tube 23 and the refrigerating room evaporator 10 are sequentially connected to one outlet of the switching valve 22, and the freezing capillary tube 24 and the freezing room evaporator 12 are sequentially connected to the other outlet of the switching valve 22. An accumulator 16 is connected to the evaporator 12.

  According to the refrigerator 1 having the above configuration, the refrigerant flow path is switched by the switching valve 22, and in the refrigeration mode at the time of cooling the freezing temperature zone 31, the combustible refrigerant is decompressed by the freezing capillary tube 24 and enters the freezer compartment evaporator 12. After cooling the refrigeration temperature zone 31, the flow returns to the compressor 15 again.

  On the other hand, in the refrigerating mode at the time of cooling in the refrigerating temperature zone 30, the flammable refrigerant is decompressed by the refrigerating capillary tube 23, enters the refrigerating chamber evaporator 10, cools the refrigerating temperature zone 30, and then passes through the freezer compartment evaporator 12. A refrigeration cycle returning to the compressor 15 is configured again.

  The combustible refrigerant in the freezing mode flows in the order of the freezing capillary tube 24, the freezer compartment evaporator 12, and the accumulator 16, and cold air circulates in the refrigerator by the operation of the freezing compartment cooling fan 13, and the first and second freezing compartments. 6 and 7 are cooled.

  In the refrigeration mode, when the switching valve 22 is switched and the refrigerant flow path is switched from the refrigeration temperature zone 31 side to the refrigeration temperature zone 30 side, the flammable refrigerant flows into the refrigeration chamber evaporator 10 and is refrigerated and stored by operating the refrigeration chamber fan 11. Cool chamber 4 and vegetable chamber 5.

(2) Structure of the electric system of the refrigerator 1 The structure of the electric system of the refrigerator 1 is demonstrated based on the block diagram of FIG.

  As shown in FIG. 8, a three-phase brushless DC motor (hereinafter referred to as a “comp motor”) 28 that drives the compressor 15, a drive device (hereinafter referred to as a “comp drive device”) 32 that drives the compressor motor 28, and this compressor It is comprised from the main control part 33 of the refrigerator 1 which controls the drive device 32. FIG. Further, the main control unit 33 is connected to door switches 4b to 7b provided in the doors 4a to 7a of the rooms 4, 5, 6 and 7, respectively. Furthermore, a deodorizing device 35, a defrosting heater 26, and an R sensor 34 are connected to the main control unit 33.

  First, the structure of the comp drive device 32 will be described.

  The compressor driving device 32 includes an inverter circuit 42, a rectifying circuit 44, an AC power supply 46, a PWM forming unit 48, an AD converting unit 50, a dq converting unit 52, a speed detecting unit 54, and a speed command output unit 56. A speed PI control unit 58, a q-axis current PI control unit 60, a d-axis current PI control unit 62, a three-phase conversion unit 64, and an initial pattern output unit 66.

  The compressor motor 28 that rotates the compressor 15 is a three-phase brushless DC motor as described above. The inverter circuit 42 causes a three-phase drive current to flow through the three-phase (u-phase, v-phase, and w-phase) stator windings 40u, 40v, and 40W of the comp motor 28.

  The inverter circuit 42 is a full bridge inverter circuit composed of transistors Tr1 to Tr6 which are six power switching semiconductors. Although not shown in the figure, a diode is connected in reverse to the switching transistors Tr1 to Tr6 in parallel. A detection resistor R1 for detecting a drive current is connected in series to the switching transistors T1 and Tr4, a detection resistor R2 is connected in series to the switching transistors Tr2 and Tr5, and a detection resistor R28 is connected in series to the switching transistors Tr28 and Tr6. Is connected.

  The rectifier circuit 44 is supplied with an AC voltage from an AC power supply 46 that is a commercial power supply (AC 100 V), and rectifies and supplies it to the inverter circuit 42.

  The PWM forming unit supplies a PWM signal to the gate terminals of the six switching transistors Tr1 to Tr6. The PWM forming unit 48 performs pulse width modulation based on three-phase voltages Vu, Vv, and Vw, which will be described later, and turns on / off the switching transistors Tr1 to Tr6 at a predetermined timing.

  The AD converter 50 detects the voltage values at the shunt resistors R1, R2, and R28, converts the voltage values of each phase from analog values to digital values, and outputs three-phase drive currents Iu, Iv, and Iw.

  The dq conversion unit 52 corresponds to the drive currents Iu, Iv, and Iw output from the AD conversion unit 50 to the d-axis (direct-axis) current Id that is a current component corresponding to the magnetic flux and the torque of the comp motor 28. It is converted to a q-axis (quadrature-axis) current Iq.

次に、このように変換した二相の電流Ｉα，Ｉβをｑ軸電流Ｉｑとｄ軸電流Ｉｄに（２）式を用いて変換する。この二相の駆動電流と変換（検知）したｑ軸電流Ｉｑとｄ軸電流Ｉｄとの関係は図１０に示すベクトル図のような関係を有する。

速度検出部５４では、検知したｑ軸電流Ｉｑとｄ軸電流Ｉｄに基づいて、コンプモータ２８の回転角θと回転速度ωを検出する。ｑ軸電流とｄ軸電流に基づいてコンプモータ２８の回転子の位置である回転角θを求め、このθを微分することにより回転速度ωを求める。 In this conversion method, three-phase Iu, Iv, and Iw are converted into two-phase Iα and Iβ as shown in the equation (1). FIG. 9 is a vector diagram showing the relationship between the three-phase current and the two-phase current.

Next, the two-phase currents Iα and Iβ converted in this way are converted into a q-axis current Iq and a d-axis current Id using the formula (2). The relationship between the two-phase drive current, the converted (detected) q-axis current Iq, and the d-axis current Id is as shown in the vector diagram of FIG.

The speed detector 54 detects the rotation angle θ and the rotation speed ω of the comp motor 28 based on the detected q-axis current Iq and d-axis current Id. Based on the q-axis current and the d-axis current, a rotation angle θ which is the position of the rotor of the comp motor 28 is obtained, and the rotational speed ω is obtained by differentiating this θ.

  The main control unit 33 of the refrigerator 1 outputs a speed command signal S based on the q-axis current Iq sent from the dq conversion unit 52.

  The speed command output unit 56 outputs a reference rotation speed ωref based on the speed command signal S from the main control unit 33 and the rotation speed ω from the speed detection unit 54. The reference rotational speed ωref is input to the speed PI control unit 58 together with the current rotational speed ω.

  The speed PI control unit 58 performs PI control based on the difference between the reference rotational speed ωref and the current rotational speed ω, outputs the reference q-axis current Iqref and the reference d-axis current Idref, and the current q-axis current Iq. And the current d-axis current Id are output to the q-axis current PI control unit 60 and the d-axis current PI control unit 62, respectively.

  The q-axis current PI control unit 60 performs PI control, performs current / voltage conversion, and outputs a reference q-axis voltage Vq.

  The d-axis current PI control unit 62 performs PI control and current / voltage conversion, and outputs a reference d-axis voltage Vd.

この変換された二相の電圧Ｖα，Ｖβを、三相の電圧Ｖｕ，Ｖｖ，Ｖｗに（４）式に基づいて変換する。

この変換された三相の電圧Ｖｕ，Ｖｖ，Ｖｗを前記したＰＷＭ形成部４８に出力する。 The three-phase converter 64 first converts the reference d-axis voltage Vd and the reference q-axis voltage Vq into a two-phase voltage based on the equation (3).

The converted two-phase voltages Vα, Vβ are converted into three-phase voltages Vu, Vv, Vw based on the equation (4).

The converted three-phase voltages Vu, Vv, and Vw are output to the PWM forming unit 48 described above.

  According to the compressor driving device 32 described above, the rotational speed is detected based on the detected d-axis current Id and q-axis current Iq, and feedback control is performed based on the rotational speed ω and the speed command signal S from the main control unit. The PWM forming unit 48 outputs a PWM signal to the inverter circuit 42 so that the compressor motor 28 rotates at the rotational speed ωref that matches the speed command signal S. Based on this, the inverter circuit 42 outputs a three-phase drive current to the three-phase stator winding 40 of the compressor motor 28.

  The initial pattern output unit 66 is set with a starting motor constant when the compressor 15 is started. At the time of starting, the starting characteristics are determined by the set starting motor constant. The startup motor constants set are the initial rotation position θinit, the startup acceleration speed ωinit, the startup d-axis current Idinit, and the startup q-axis current Iqinit. The startup acceleration speed ωinit is output to the speed command output unit 56, and the initial rotation speed The position θinit is output to the dq converter 52, and the starting d-axis current Idinit and the starting q-axis current Iqinit are output to the speed PI control unit 58. This starting control will be described later.

(3) Structure and Operation State of Compressor 15 (3-1) Structure of Compressor 15 Next, the structure of the reciprocating hermetic compressor 15 will be described with reference to FIGS.

  FIG. 1 shows a front view of the compressor 15 in a longitudinal section.

  The refrigerant that is a compressed fluid is isobutane (R600a) that is a natural combustible refrigerant as described above.

  A frame 102 is elastically supported via a spring 102a at a substantially middle portion in the vertical direction in the vertical sealed case 101 of the compressor 15. A compression mechanism 103 is mounted on the upper side of the frame 102, and a comp motor 28 is provided on the lower side. The compression mechanism unit 103 employs a so-called reciprocating compression mechanism.

  A pivot hole 102b is provided along the center of the frame 102, and a rotary shaft 105 as a main shaft is fitted rotatably. The upper end portion of the rotating shaft 105 is integrally provided with a flange portion 105a that is slidably mounted on the upper surface of the frame 102. The upper portion of the flange portion 105a has a central axis that is eccentric by a predetermined amount from the central axis of the rotating shaft 105. A crankpin 105b having a continuous structure is provided. Therefore, when the rotary shaft 105 is driven to rotate, the flange portion 105a rotates in a sliding contact state on the upper surface of the frame 102, and the crank pin 105b rotates eccentrically along the periphery of the center of the rotary shaft 105.

  The compression mechanism unit 103 is provided on the upper surface of the frame 102 and includes a cylinder 106 with the axial direction oriented horizontally. Inside the cylinder 106 is a cylinder chamber 108 in which a piston 107 is reciprocally accommodated. One end of a crank 109 is connected to the piston 107 via a ball joint mechanism 110. The other end of the crank 109 is provided with an end 111 that is rotatably fitted to the crank pin 105b.

  The ball joint mechanism 110 will be described. A ball 112 is integrally provided at one end of the crank 109. On the other hand, a ball receiving seat 113 is provided inside the piston 107. The ball receiving seat 113 holds the ball 112 in a rotatable manner. Thereby, with the eccentric rotation of the crank pin 105 b, the crank 109 can swing with the ball joint mechanism 110 as a fulcrum, and the piston 107 reciprocates within the cylinder 106.

  The open end of the cylinder 106 is closed by the valve mechanism 115 and covered with the valve cover 116. The valve cover 116 is provided with a partition portion that bisects the interior, one of which is a suction chamber and the other is a discharge chamber.

  The valve mechanism 115 is provided with a valve plate having a suction port and a discharge port, and the suction port and the discharge port are opened and closed by the suction valve and the discharge valve. The suction port faces the suction chamber, and the discharge port faces the discharge chamber.

  With respect to the compression mechanism portion 103 configured as described above, the compressor motor 28 includes a rotor 117 fitted to a portion of the rotating shaft 105 that protrudes downward from the frame 102, and a peripheral surface of the rotor 117. It includes an inner peripheral surface having a narrow gap and a stator 118 that is suspended and fixed from the frame 102 by appropriate means.

(3-2) Structure of Comp Motor 28 As shown in FIG. 4, the comp motor 28 is a brushless DC motor, and is a three-phase six-slot four-pole motor. That is, the four-pole rotor 117 rotates on the inner peripheral side of the three-phase six-slot stator 118.

  When a voltage is applied to each phase of the comp motor 28 by the comp driving device 32, the same control is performed symmetrically 180 ° inside the motor. Further, as shown in FIG. 2, since the crank 109 is at one place, when a current in three phases is passed during positioning at the time of starting, the crank 109 is either 180 ° symmetric depending on the stop position (FIGS. 2 and 3). Move to.

(3-3) Operation State of Compressor 15 Next, the compression operation of the compressor 15 and the accompanying refrigeration cycle action will be described.

  When the compressor motor 28 is energized and the rotary shaft 105 is driven to rotate, the crank pin 105b rotates eccentrically. In response to this eccentric rotation, the piston 107 reciprocates in the cylinder chamber 108 via the crank 109 and the ball joint mechanism 110.

  The sealed case 101 is filled with refrigerant gas that has been evaporated by an evaporator and reduced in pressure. This refrigerant gas is guided to the suction chamber in the valve cover 116 and further sucked into the cylinder chamber 108 of the cylinder 106 as the piston 107 moves (forward movement).

  As the piston 107 moves in the reverse direction (return), the refrigerant gas is compressed. When the piston 107 moves to a so-called top dead center position, the discharge valve is opened, and the refrigerant gas compressed in the cylinder chamber 108 and increased in pressure is discharged into the discharge chamber of the valve cover 116.

  The high-pressure refrigerant gas is led out from the sealed case 101 to the external refrigerant pipe via the in-case discharge pipe and led to the refrigeration cycle. From the place where the rotating shaft 105 continues to rotate, the piston 107 moves backward and the refrigeration cycle is repeated.

  As shown in FIGS. 2 and 3, the crank pin 105 b rotates eccentrically with the rotation of the rotating shaft 105, and the center P of the crank pin 105 b draws a circular rotation locus A with the eccentric amount as the rotation radius. The crank 109 performs a swinging motion having a predetermined swinging angle α, and in the ball joint mechanism 110, the ball 112 and the ball receiving seat 113 slide with each other.

  When compressing the refrigerant gas introduced into the cylinder chamber 108, a load (F) is applied to the top surface of the piston 107, and the force acts on the ball joint mechanism 110 via the piston 107.

(4) Control method at start-up The compressor 15 is started by energizing for a predetermined time (for example, 3 seconds), moving the rotor to a predetermined position and starting the start. In this case, the 180-degree symmetrical movement due to the 4-pole rotor 117 varies depending on the stop position of the rotor 117.

  Therefore, it is necessary that the rotor 117 can be normally started from any starting position. When accelerating at a predetermined acceleration at the time of startup, the speed at the position where the compression work that requires the most torque changes depending on the starting position. It is necessary to control the starting position. In general, in the vector control, it is preferable to start activation after the pressure difference between the suction port and the discharge port of the compressor 15 disappears, but it is necessary to activate the pressure difference (for example, 300 Pa). That is, even when there is a pressure difference between the suction port and the discharge port of the compressor 15, the compressor 15 can be started normally and it is necessary to perform optimal refrigeration cycle control.

  Therefore, in the present embodiment, θinit is rotated by 45 ° with respect to a line connecting the piston 107, compression top dead center, and bottom dead center as an optimum position for this activation. Hereinafter, the position rotated 45 ° from the position of the top dead center or the bottom dead center is referred to as “starting initial position”. The reason why this position is optimal is that, as shown in FIG. 5, when 0 ° is set, the torque is minimized at the bottom dead center but maximized at the top dead center, and the rotor 117 is stopped at the top dead center. This is because there is a high possibility that the activation will fail, and the torque is still large even at 30 ° or 60 °, and the position of 45 ° has the highest probability of successful activation.

  As shown in FIGS. 2 and 3, there are two starting initial positions symmetrically at 180 °. That is, FIG. 2 and FIG. 3 are schematic plan views in which a part of the compression mechanism portion 103 is cross-sectionally shown. The eccentric rotation motion of the crank pin 105b, the accompanying swing motion of the crank 109, and the ball joint mechanism. The relationship with the part 110 and the piston 107 is shown. In FIGS. 2 and 3, the compression top dead center is a 0 ° position, and the bottom dead center is a 180 ° position. FIG. 2 is a position where the crank 109 is rotated by 45 ° from the compression top dead center, and FIG. 3 is a position where the crank 109 is rotated by 45 ° from the bottom dead center.

  Then, the rotational position of the rotor 117 when the crank 109 is at the top dead center and the rotational position of the rotor 117 when the crank 109 is at the bottom dead center are associated with each other, and the comp motor 32 is operated by the comp driving device 32. At least one phase of each of the 28 phases is energized, and the rotation position of the rotor 117 is rotated by 45 ° from the top dead center (see FIG. 2), and is rotated by 45 ° from the bottom dead center (see FIG. 3). The starting motor constant is set in advance so that the operation stops. That is, as the starting motor constants for moving the rotor 117 to the starting initial position, the initial rotation position θinit, the starting acceleration speed ωinit, the starting d-axis current Idinit, and the starting q-axis current Iqinit are set in the initial pattern output unit 66 in advance. Keep it.

  Thus, before the compressor 15 is started, the compressor driving device 32 causes the driving current to flow to the compressor motor 28 in at least one phase based on the above-described starting motor constant, and waits for the position of the rotor 117 to the starting initial position. Let Thereafter, by starting rotation from this starting initial position by rotating at the starting rotational speed (for example, 40 Hz), the starting torque can be started from a small state, and the rotor 117 can be normally started from any starting position.

  In the state where there is no pressure difference between the suction port and the discharge port of the compressor 15, the rotation speed may be too high and the start-up may fail. For this reason, the start-up rotation speed may be reduced (for example, 40 Hz is reduced by 10 Hz to 30 Hz). Or if the startup is started by rotating the position by 10 ° or 60 ° rather than 45 ° instead of 45 °, the torque may be slightly heavier, and the startup may fail without being too fast. Absent.

(5) Modified Example In the above embodiment, as the starting initial position, the rotation position of the rotor 117 is rotated by 45 ° from the top dead center (see FIG. 2), and the position rotated by 45 ° from the bottom dead center (FIG. 3). However, the present invention is not limited to this, and it can be reliably started within the range of 40 ° to 50 °.

  Moreover, although the said embodiment demonstrated the combustible refrigerant | coolant, a nonflammable refrigerant | coolant may be sufficient.

  Furthermore, in the compressor 15 of the above-described embodiment, the ball joint type has been described. However, the structure is not limited to this, and other structures may be used as long as the piston moves.

  The compressor driving device of the present invention can be used for a domestic refrigerator or a compressor of an air conditioner.

It is a vertical front view of the reciprocating hermetic compressor of one embodiment of the present invention. It is a figure for demonstrating the position of the top dead center of the compression mechanism part of this embodiment. It is a figure for demonstrating the position of the bottom dead center of the compression mechanism part of this embodiment. It is explanatory drawing of a compressor motor. It is a graph which shows the starting success probability with respect to (theta) init in this embodiment. It is sectional drawing of the refrigerator which shows this embodiment. It is a refrigerating cycle figure of the refrigerator of this embodiment. It is a block diagram of the refrigerator of this embodiment. It is a vector diagram which performs αβ change from three phases. It is a vector diagram which changes dq from αβ.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerator 15 Compressor 28 Comp motor 32 Comp drive device 33 Main control part 42 Inverter circuit 48 PWM formation part 52 dq conversion part 64 Three phase conversion part 66 Initial pattern output part 101 Sealing case 105 Rotating shaft 105b Crank pin 107 Piston 108 Cylinder chamber 109 Crank 110 Ball joint mechanism

Claims (4)

A reciprocating compressor rotating with a three-phase brushless DC motor, a condenser, and a refrigeration cycle having at least an evaporator;
In the compressor driving device for compressing the refrigerant by the compressor and cooling the evaporator,
An inverter circuit for supplying a three-phase drive current to the stator winding of the brushless DC motor;
A PWM circuit for supplying a PWM signal to the inverter circuit;
Drive current detection means for detecting the three-phase drive current;
Based on the detected three-phase drive current, a d-axis current that is a current component corresponding to the magnetic flux of the rotor of the brushless DC motor, and a q-axis current that is a current component corresponding to the torque of the brushless DC motor, Dq conversion means for converting to
Control means for outputting a reference q-axis current and a reference d-axis current based on the converted d-axis current, the q-axis current, and a speed command signal input from the outside;
Voltage converting means for converting the reference q-axis current and the reference d-axis current into a reference q-axis voltage and a reference d-axis voltage;
Three-phase conversion means for converting the converted reference q-axis voltage and reference d-axis voltage into a three-phase voltage and outputting the same to the PWM circuit;
Initial pattern output for rotating the brushless DC motor rotor to a starting initial position which is a position rotated by 40 ° to 50 ° with reference to a line connecting the position of the piston of the compressor and a compression top dead center and a bottom dead center Means,
Starting means for starting the compressor from the starting initial position;
A compressor driving device characterized by comprising: The compressor driving device according to claim 1, wherein the brushless DC motor has three-phase four-pole. 2. The compressor driving device according to claim 1, wherein the starting initial position is a position rotated by 45 ° with respect to a line connecting the position of the piston, a compression top dead center, and a bottom dead center. A refrigerator using the compressor drive device according to at least one of claims 1 to 3.

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