JP2007267451A - Apparatus and method for controlling reciprocating compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for controlling a reciprocating compressor wherein a reciprocating compressor is operated by utilizing inertia torque without failure in startup, even when load torque is high, and configuration simplification and price reduction are achieved. <P>SOLUTION: The controlling apparatus includes: a synchronous motor 131 that has a permanent magnet in its rotor, and is for driving a reciprocating compressor 13; an inverter circuit 12 for driving the synchronous motor 131; and a control unit 14 for controlling the inverter circuit 12. The control unit 14 includes a start control unit 145. When the synchronous motor 131 is started, the start control unit in the control unit 14 supplies the inverter circuit 12 with a reverse rotation command for reversely rotating the synchronous motor 131 with a motor torque having a value not exceeding the maximum value of load torque for a predetermined time; and when a predetermined time has passed, the start control unit supplies a normal rotation command for normally rotating the synchronous motor 131. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device and a control method for a reciprocating compressor (reciprocating compressor), and more particularly, to a control device and a control method for a reciprocating compressor that performs control for giving a reverse rotation command when the reciprocating compressor is started. .

  The reciprocating compressor is used in a refrigerator and the like, and a synchronous motor having a permanent magnet in a highly efficient rotor is often used as a driving motor of the reciprocating compressor.

  Due to its structure, the reciprocating compressor has a characteristic that the load torque is small in the refrigerant gas intake stroke, but the load torque is large in the refrigerant gas compression stroke.

  FIG. 6 is a structural diagram of a reciprocating compressor. In FIG. 6, one end of a connecting rod 2 is connected to one end of the circumference of the motor rotor 1, and the other end of the connecting rod 2 is connected to a piston 3 provided in a cylinder 4. The rotational motion of the motor rotor 1 is converted into linear motion (reciprocating motion) in the cylinder 4 via the connecting rod 2. For this reason, when the motor rotor 1 makes one revolution, the piston 3 reciprocates once.

  As shown in FIG. 6, when the rotation direction of the motor is counterclockwise, the force Fg that the refrigerant gas gives to the piston 3 is expressed by the load torque with respect to the angle θ of the motor rotor 1 as shown in FIG. Become. That is, FIG. 7 shows the relationship between the motor rotor angle and the load torque. In FIG. 7, the motor rotor angle θ is positive in the counterclockwise direction. Further, the X-axis direction is set to 0 radians (θ = 0), and the motor rotor angle θ is set counterclockwise around the rotation center O of the motor rotor 1. Therefore, θ = 3π / 2 when the piston 3 is at the lowest end (position where the suction stroke is shifted to the compression stroke).

  As can be seen from FIG. 7, the load torque becomes the largest when the angle θ of the motor rotor 1 is near 0 radians (or near 2π radians). Further, when the refrigerant gas pressure on the discharge side of the reciprocating compressor is high, the maximum value of the load torque is further increased.

  When the load torque increases in this way, a large motor torque is required when the reciprocating compressor is started. In particular, it is more difficult to start the reciprocating compressor when the motor rotor 1 is in the compression stroke.

  In order to increase the motor torque at the start-up, there is a method of increasing the current. However, it is necessary to increase the current capacity of the switching element of the inverter circuit that drives the motor. In this case, however, the efficiency is deteriorated and the permanent magnet used for the motor rotor is demagnetized. .

  For this reason, once the reciprocating compressor stops operating, the reciprocating compressor is not immediately restarted, and after the pressure of the discharge side refrigerant gas of the reciprocating compressor has dropped after a certain period of time, the reciprocating compressor In many cases, a sequence for driving is set. This is because when the pressure of the refrigerant gas is high, activation of the reciprocating compressor is likely to fail, so a pause state for a certain period is required.

  Further, for example, Patent Document 1 is known as a conventional technique. The activation control device for a reciprocating device drive motor described in Patent Document 1 includes a current detection circuit that detects an overcurrent of a DC input current of an inverter, and a forward / reverse switching circuit that switches a phase rotation direction of the inverter. . When the rotation angle position at the time of starting is 3π / 2 to 0 (or 2π), the starting torque increases, a large starting current flows, and the current detection circuit detects an overcurrent at the time of starting. Then, after the control circuit stops the motor start operation of the inverter for a predetermined time, the forward / reverse switching circuit is operated to reverse the phase rotation direction of the inverter and restart the crankshaft in the reverse rotation direction.

As a result, if the electric motor is rotated in the reverse direction, the rotation direction becomes the direction of torque reduction and can be easily started. In other words, the output current capacity can be reduced because it can be rotated in a direction that is easy to start.
JP 60-134783 A

  However, in the activation control device for a reciprocating device drive motor described in Patent Document 1, it is necessary to provide a current detection circuit for detecting an overcurrent, which complicates the circuit configuration and increases the cost. become.

  Moreover, it rotates in the direction in which the starting torque decreases with respect to the rotational angle position of the motor. That is, depending on the rotation angle position, the electric motor continues to rotate in the forward rotation direction, or the electric motor continues to rotate in the reverse rotation direction. For this reason, the current detection circuit must detect the overcurrent of the DC input current of the inverter in the forward rotation direction of the electric motor and detect the overcurrent of the DC input current of the inverter in the reverse rotation direction of the electric motor, The configuration is further complicated and the cost is further increased.

  The problem of the present invention is that even when the pressure of the refrigerant gas of the reciprocating compressor is high and the load torque is large, it is possible to operate the reciprocating compressor without failing using the torque due to inertia, and the configuration is simple and inexpensive. Another object of the present invention is to provide a control device and a control method for a reciprocating compressor.

  In order to solve the above problems, the present invention employs the following means. A control device for a reciprocating compressor according to claim 1 comprises a synchronous motor having a permanent magnet in a rotor and driving the reciprocating compressor, an inverter circuit for driving the synchronous motor, Control means for controlling an inverter circuit, and when the synchronous motor is started, the control means controls the synchronous motor with a motor torque having a value that does not exceed a maximum value of load torque with respect to the inverter circuit. It has a starting control part which gives the reverse rotation command for reverse rotation for a predetermined time, and gives the normal rotation command for rotating the synchronous motor forward after the predetermined time passes.

  According to a second aspect of the present invention, in the control device for the reciprocating compressor according to the first aspect, the start control unit is a stop for stopping the synchronous motor between the reverse rotation command and the forward rotation command. A command is provided.

  According to a third aspect of the present invention, in the control device for the reciprocating compressor according to the first or second aspect, the start control unit sets the X-axis direction to 0 radians and counterclockwise about the rotation center of the motor rotor. When the motor rotor angle is set, the reverse rotation command is given for the predetermined time to move the motor rotor angle position at the time of starting the synchronous motor to a position of π to 3π / 2. And

  According to a fourth aspect of the present invention, there is provided a reciprocating compressor control method comprising: a driving step of driving a synchronous motor having a permanent magnet in a rotor and driving a reciprocating compressor by an inverter circuit; and controlling the inverter circuit. A control step for causing the inverter circuit to reversely rotate the synchronous motor with a motor torque that does not exceed a maximum load torque when the synchronous motor is started. The reverse rotation command is applied for a predetermined time, and after the predetermined time has elapsed, a start-up control step of applying a normal rotation command for causing the synchronous motor to rotate forward is provided.

  According to a fifth aspect of the present invention, in the control method for the reciprocating compressor according to the fourth aspect, the start control step is a stop for stopping the synchronous motor between the reverse rotation command and the forward rotation command. A command is provided.

  According to a sixth aspect of the present invention, in the control method for the reciprocating compressor according to the fourth or fifth aspect, the start control step is performed in the counterclockwise direction about the rotation center of the motor rotor with the X axis direction set to 0 radians. When the motor rotor angle is set, the reverse rotation command is given for the predetermined time to move the motor rotor angle position at the time of starting the synchronous motor to a position of π to 3π / 2. And

  According to the first and fourth aspects of the invention, when starting the synchronous motor, the start control unit causes the inverter circuit to reversely rotate the synchronous motor with a motor torque that does not exceed the maximum load torque. The reverse rotation command is given for a predetermined time, so that the synchronous motor rotates reversely and load torque is applied, so that the rotation speed of the motor rotor decreases, and the motor rotor eventually stops without overcoming the load torque. Then, when a normal rotation command for causing the synchronous motor to rotate in the forward direction is given, the rotation direction becomes the load torque decreasing direction, and the synchronous motor can be easily started without increasing the motor torque.

  Therefore, even when the refrigerant gas pressure of the reciprocating compressor is high and the load torque is large, the reciprocating compressor can be operated without fail using the torque due to inertia, and a current detection circuit as in the past is provided. The configuration is simple and inexpensive. Moreover, the stop period from the stop of the normally provided reciprocating compressor to restart can be shortened.

  According to the second and fifth aspects of the present invention, a stop command is provided between the reverse rotation command and the normal rotation command, so that even if the pressure difference between the discharge pressure and the suction pressure of the reciprocating compressor is large, the operation is started. The success rate can be increased.

  According to the third and sixth aspects of the invention, when the X-axis direction is set to 0 radians and the motor rotor angle is set counterclockwise around the rotation center of the motor rotor, a reverse rotation command is given for a predetermined time. By moving the motor rotor angular position at the time of starting the synchronous motor to a position of π to 3π / 2 by giving a positive rotation command, the rotational direction becomes the load torque decreasing direction and the motor torque is increased. The synchronous motor can be started easily without any problems.

  Embodiments of a control device and a control method for a reciprocating compressor according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a configuration diagram of a control device for a reciprocating compressor according to a first embodiment of the present invention. The reciprocating compressor control device shown in FIG. 1 includes a commercial power supply 10, a rectifier circuit 11, an inverter circuit 12, a reciprocating compressor 13, and a control unit 14.

  The commercial power supply 10 supplies an AC voltage of 100 V or 200 V to the rectifier circuit 11 as electric power necessary for driving the reciprocating compressor 13. The rectifier circuit 11 converts the AC voltage of the commercial power supply 10 into a DC voltage. Here, the rectifier circuit 11 is constituted by a full-wave rectifier circuit, and the full-wave rectifier circuit is connected in parallel to the four diodes D1 to D4 connected in a bridge and the four diodes D1 to D4. And a smoothing capacitor C1.

  The inverter circuit 12 converts the DC voltage of the rectifier circuit 11 into an AC voltage, and drives the synchronous motor 131 by this AC voltage. The inverter circuit 12 is composed of six switching elements Q1 to Q6 connected in a three-phase bridge and six diodes D5 to D10 connected in parallel to the six switching elements Q1 to Q6 in the reverse direction. Yes. The six switching elements Q1 to Q6 are made of, for example, insulated gate bipolar transistors.

  The connection point between the switching element Q1 and the switching element Q2 is connected to the first phase (U phase) of the synchronous motor 131, and the connection point between the switching element Q3 and the switching element Q4 is the second phase (V The connection point between the switching element Q5 and the switching element Q6 is connected to the third phase (W phase) of the synchronous motor 131.

  The control unit 14 controls the inverter circuit 12. That is, by applying a control signal from the control unit 14 to the gates of the six switching elements Q1 to Q6, the six switching elements Q1 to Q6 are subjected to switching control, and the inverter circuit 12 has a desired voltage. Can get the frequency.

  The reciprocating compressor 13 includes a synchronous motor 131 having a permanent magnet in the rotor and a compression mechanism 132, and the compression mechanism 132 is operated by the rotation of the synchronous motor 131 to compress the refrigerant gas. This reciprocating compressor 13 corresponds to the configuration shown in FIG. 6, and the motor rotor 1 shown in FIG. 6 corresponds to the motor rotation shaft of the synchronous motor 131 shown in FIG. 1, and the connecting rod shown in FIG. 2, the piston 3 and the cylinder 4 correspond to the compression mechanism 132 shown in FIG.

  Although not shown, the synchronous motor 131 includes a stator having three-phase windings and a rotor having permanent magnets. In general, the rotor is configured by alternately arranging N poles and S poles of 4-pole or 6-pole permanent magnets.

  The rotational speed of the rotor of the synchronous motor 131 with respect to the frequency output from the inverter circuit 12 is ½ of the inverter output frequency when the permanent magnet has 4 poles, and when the permanent magnet has 6 poles. 1/3 of the inverter output frequency. That is, the motor rotor 1 rotates 1/2 or 1/3 with respect to one cycle of the frequency output from the inverter circuit 12. Therefore, the motor rotor 1 passes through the point where the load torque becomes the largest once every two or three periods of the frequency output from the inverter circuit 12.

  The control unit 14 includes a position detection unit 141, a speed control unit 142, an output signal generation unit 143, a drive unit 144, and an activation control unit 145. For example, the control unit 14 receives a rotational speed command for rotating the synchronous motor 131 from an external device, and controls the output voltage and output frequency of the inverter circuit 12 so as to correspond to the rotational speed command.

  The activation control unit 145 generates and outputs a reverse rotation command for reversely rotating the synchronous motor 131 when receiving a rotational speed command from the stop command state from an external device. Thereafter, a normal rotation command for rotating the synchronous motor 131 in the normal direction is output, and the synchronous motor 131 is accelerated.

  That is, when starting the synchronous motor 131, the start control unit 145 gives a reverse rotation command to the inverter circuit 12 with a motor torque that does not exceed the maximum value of the load torque for a predetermined time. A forward rotation command is given. At this time, the activation control unit 145 moves the motor rotor angular position to the position of π to 3π / 2 when the synchronous motor 131 is activated by giving a reverse rotation command for a predetermined time. The rotational speed command, reverse rotation command, and forward rotation command of the start control unit 145 are sent to the speed control unit 142.

  It is difficult to attach a sensor for detecting the shaft angle (motor rotor angle) of the synchronous motor 131 and the position of the piston in the reciprocating compressor 13 because of the structure of the reciprocating compressor. For this reason, the position detection unit 141 detects the position of the motor rotor angle of the synchronous motor 131 based on the output voltage and output current signals of the inverter circuit 12.

  As the simplest position detection and phase switching method of the motor rotor angle of the synchronous motor 131, for example, the voltage of a phase that is not conductive at the top and bottom among the six switching elements Q1 to Q6 is detected, and this voltage is present. There is a method of switching the output phase based on the time when the reference point is crossed. In this method, the instantaneous position of the motor rotor 1 is not known, but a phase switching operation can be performed. The phase is switched every π / 6, and the position detector 141 outputs phase switching information. The speed control unit 142 calculates the rotation speed of the motor rotor 1 based on the phase switching information from the position detection unit 141.

  Further, the speed control unit 142 compares the rotational speed command from the activation control unit 145 with the motor rotational speed obtained by calculation, and calculates the necessary motor torque according to the difference between the rotational speed command and the motor rotational speed. Find the output voltage to be generated.

  The output signal generation unit 143 determines the pulse width of the output signal based on the output voltage from the speed control unit 142 and the phase switching information from the position detection unit 141, and provides a process in which the upper and lower switching elements are not conductive. To output an output signal to the drive unit 144. The command signal generated by the output signal generation unit 143 is output to the drive unit 144, and the drive unit 144 drives the switching elements Q1 to Q6 of the inverter circuit 12.

(Control processing when starting up a reciprocating compressor)
Next, the control process at the time of starting the reciprocating compressor will be described in detail. When the reciprocating compressor 13 used in a refrigerator or the like is driven by the inverter circuit 12, the inverter circuit 12 is used to perform a defrosting operation of the evaporator for lowering the set temperature in the refrigerator or for cooling. The stop is made several times a day.

  As the inverter circuit 12 stops, the synchronous motor 131 also stops. Although the motor rotor angle θ when the synchronous motor 131 stops is not constant, it is often in the region of θ = 3π / 2 to 0 (or 2π) where the load torque increases.

  Immediately after the inverter circuit 12 is stopped, the refrigerant pressure is compressed by the reciprocating compressor 13, so the gas pressure is high. The gas pressure decreases with time, and generally the gas pressure reaches a stable state in a few minutes.

  In order to overcome the load torque due to the gas and maintain a desired rotation direction (for example, normal rotation), the motor torque of the synchronous motor 131 is T, the moment of inertia of the motor rotor 1 is J, and the rotation of the motor rotor 1 is rotated. When the speed is ωm and the load torque is TL, the motor rotational speed ωm needs to be kept positive according to the equation (1).

T = J × (dωm / dt) −TL (1)
FIG. 2 is a diagram showing the relationship between the motor torque, load torque, and motor rotor rotational speed when the motor rotor angular position is in a state of 3π / 2 to 0 when the reciprocating compressor is started. It is in the state of θ = 3π / 2 to 0 that the motor rotor angular position at the time of starting is considered to stop normally.

  FIG. 3 is a diagram showing the relationship between the motor torque, load torque, and motor rotor rotational speed when a reverse rotation command is given once at the time of starting the reciprocating compressor and the motor rotor angular position is π to 3π / 2. is there. FIGS. 2A and 3A show the motor torque T, which is constant. FIG. 2B and FIG. 3B show the load torque TL. FIG. 2C and FIG. 3C show the rotational speed ωm of the motor rotor 1.

  At time t1, the synchronous motor 131 is activated by the motor torque T to start acceleration, but at time t2, T = TL. Further, after time t2, T <TL, and the state changes from acceleration to deceleration. If this state is continued, finally, at time t3, ωm = 0 and the synchronous motor 131 stops.

  On the other hand, in FIG. 3, at time t1, the synchronous motor 131 is activated to start acceleration, and the load torque TL is applied from time t4. At time t5, T <TL and the rotational speed ωm starts to decelerate. However, since the synchronous motor 131 has a sufficient rotational speed ωm at time t5, the synchronous motor 131 continues to rotate forward until T> TL again at time t6. Since then, it has continued to accelerate.

  As described above, even if the motor torque T is the same, the synchronous motor 131 stops depending on the motor rotor angle θ, and whether or not the activation fails varies.

  FIG. 4 is a diagram showing motor torque, load torque, and motor rotor angle when the reciprocating compressor according to the first embodiment of the present invention is started. 4A shows the motor torque T, FIG. 4B shows the load torque TL, and FIG. 4C shows the motor rotor angle θ of the motor rotor 1.

  In the first embodiment, as shown in FIG. 2, even when the motor rotor angle θ is close to the maximum value of the load torque TL, by giving a reverse rotation command at startup, the motor rotor angle at startup is set to θ = It moves to the position of π-3π / 2 and operates so as to reduce the startup failure.

(Reverse rotation operation of synchronous motor 131)
Next, the reverse rotation operation of the synchronous motor 131 will be described in detail below. When the motor rotor angle is θ = 3π / 2 to 0 (or 2π) (in the case shown in FIG. 2), the motor rotor angle θ when the reverse rotation command is given to the inverter circuit 12 is shown. It is FIG.4 (c).

  At time t1, the motor rotor angle is at a position of θ = 3π / 2 to 2π, and in order to cause the synchronous motor 131 to rotate in reverse, the activation control unit 145 applies the load torque TL to the inverter circuit 12. A reverse rotation command for reverse rotation with a motor torque T that does not exceed the maximum value is given for a predetermined time (time t1 to t4).

  For this reason, the motor torque T starts to be generated clockwise by the inverter circuit 12 (the motor torque T is negatively displayed in FIG. 4A).

  The frequency output by the inverter circuit 12 is set lower than the output frequency during normal normal rotation, and the motor torque T is set by the output voltage so as not to exceed the maximum value of the load torque TL.

  Next, at time t2, the motor rotor angle reaches θ = 3π / 2, and the load torque TL starts to be applied. When the load torque TL is applied, the rotation speed ωm of the motor rotor 1 decreases, and the motor torque 1 eventually stops overcoming the load torque TL, and the motor rotor 1 stops at time t3. The position of the motor rotor angle at this time is in the range of θ = π to 3π / 2.

  At time t <b> 4 after the predetermined time has elapsed, the activation control unit 145 gives a normal rotation command to the inverter circuit 12. As can be seen from FIG. 4A, the reverse rotation command is switched to the normal rotation command, and the normal rotation is started from time t4.

  Thus, according to the control device for the reciprocating compressor of the first embodiment, when the synchronous motor 131 is started, the start control unit 145 does not exceed the maximum value of the load torque with respect to the inverter circuit 12. Since a reverse rotation command for reverse rotation with torque is given for a predetermined time, the synchronous motor 131 rotates reversely and load torque is applied, so that the rotation speed of the motor rotor 1 decreases and eventually the motor torque cannot overcome the load torque. At this time, the motor rotor 1 stops. Then, when a normal rotation command is given to the synchronous motor 131, the rotation direction becomes the load torque decreasing direction, and the synchronous motor 131 can be easily started without increasing the motor torque.

  Therefore, even when the refrigerant gas pressure of the reciprocating compressor is high and the load torque is large, the reciprocating compressor can be operated without fail using the torque due to inertia, and a current detection circuit as in the past is provided. The configuration is simple and inexpensive. Moreover, the stop period from the stop of the normally provided reciprocating compressor to restart can be shortened.

  FIG. 5 is a diagram showing motor torque, load torque, and motor rotor angle when the reciprocating compressor according to the second embodiment of the present invention is started. 5A shows the motor torque T, FIG. 5B shows the load torque TL, and FIG. 5C shows the motor rotor angle θ of the motor rotor 1.

  In the second embodiment shown in FIG. 5, the activation control unit 14 provides a short-term stop command (stop period) after the reverse rotation command, and then gives a normal rotation command to start the normal rotation. .

  The operation from time t1 to time t4 is the same as the operation of the first embodiment shown in FIG. From time t4 to t5, the synchronous motor 131 is stopped, and from time t5, the starting operation is performed by forward rotation.

  By performing such control, when the difference between the discharge pressure and the suction pressure of the reciprocating compressor 13 is, for example, 6 atmospheres, the normal startup method has a startup success rate of 50%. In the method, the startup success rate is 100%.

  The present invention is applicable to a refrigerator-freezer and the like. Further, it is particularly useful for a multi-cylinder reciprocating compressor provided with a plurality of cylinders 4.

It is a block diagram of the control apparatus of the reciprocating compressor of Example 1 of this invention. It is a figure which shows the relationship between the rotational speed of a motor torque, load torque, and a motor rotor in case a motor rotor angular position exists in the state of 3 (pi) / 2-0 at the time of starting of a reciprocating compressor. It is a figure which shows the relationship between the rotational speed of a motor torque, load torque, and a motor rotor in case a reverse rotation command is once given at the time of starting of a reciprocating compressor, and a motor rotor angular position shall be (pi)-3 (pi) / 2. It is a figure which shows the motor torque at the time of starting of the reciprocating compressor of Example 1 of this invention, load torque, and a motor rotor angle. It is a figure which shows the motor torque at the time of starting of the reciprocating compressor of Example 2 of this invention, load torque, and a motor rotor angle. It is a structural diagram of a reciprocating compressor. It is a figure which shows the relationship between a motor rotor angle and load torque.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor rotor 2 Connecting rod 3 Piston 4 Cylinder 10 Commercial power supply 11 Rectifier circuit 12 Inverter circuit 13 Reciprocating compressor 14 Control part 131 Synchronous motor 132 Compression mechanism 141 Position detection part 142 Speed control part 143 Output signal generation part 144 Drive part 145 Start-up controller D1-D10 Diode Q1-Q6 Switching element

Claims (6)

A synchronous motor having a permanent magnet in the rotor and driving a reciprocating compressor;
An inverter circuit for driving the synchronous motor;
Control means for controlling the inverter circuit,
When the synchronous motor is started, the control means gives a reverse rotation command for reversely rotating the synchronous motor with a motor torque having a value not exceeding the maximum value of the load torque to the inverter circuit for a predetermined time. A control device for a reciprocating compressor, comprising: a start control unit for giving a normal rotation command for causing the synchronous motor to rotate normally after the predetermined time has elapsed.   The reciprocating compressor control device according to claim 1, wherein the start control unit provides a stop command for stopping the synchronous motor between the reverse rotation command and the forward rotation command.   The activation control unit gives the reverse rotation command for the predetermined time when the X-axis direction is set to 0 radians and the motor rotor angle is set counterclockwise around the rotation center of the motor rotor. The reciprocating compressor control device according to claim 1 or 2, wherein the angular position of the motor rotor at the time of starting the synchronous motor is moved to a position of π to 3π / 2. A driving step of driving a synchronous motor for driving a reciprocating compressor having a permanent magnet in a rotor by an inverter circuit;
A control step for controlling the inverter circuit,
In the control step, when starting the synchronous motor, a reverse rotation command for reversely rotating the synchronous motor with a motor torque that does not exceed a maximum load torque value is given to the inverter circuit for a predetermined time. A control method for a reciprocating compressor, comprising a start-up control step for giving a normal rotation command for causing the synchronous motor to normally rotate after the predetermined time has elapsed.   5. The reciprocating compressor control method according to claim 4, wherein the starting control step provides a stop command for stopping the synchronous motor between the reverse rotation command and the forward rotation command.   In the activation control step, when the motor rotor angle is set counterclockwise around the rotation center of the motor rotor with the X axis direction set to 0 radians, the reverse rotation command is given for the predetermined time, 6. The method of controlling a reciprocating compressor according to claim 4, wherein the angular position of the motor rotor at the time of starting the synchronous motor is moved to a position of [pi] to 3 [pi] / 2.

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