JP2016226184A - Compressor motor control device and electrically-driven compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent start of a compressor from being failed by disabling a rotor of a compression mechanism from starting rotations against load torque when starting the compressor.SOLUTION: When starting an electric motor 5 under synchronous control, a current is made flow through a coil 5d of each of phases of a stator 5c in a short time, an α-axis current iα and a β-axis current iβ of an orthogonal coordinate system with a position of the stator 5c defined as a reference are calculated from currents (iu, iv and iw) that flow through the coils 5d of the phases, and an electric angle of the electric motor 5 is calculated, while referring to a table 15c, from a combination of the values. When starting the electric motor 5 under synchronous control, such a current that torque exceeding the load torque of a rotor 3e at a rotation angle corresponding to the calculated electric angle is generated is made flow through the coil 5d of each of the phases.SELECTED DRAWING: Figure 10

Description

  The present invention relates to an electric compressor and a control device for a motor that rotates the electric compressor.

  For example, in a compressor used in a refrigeration cycle, a rotor in a cylinder is rotated to compress fluid sucked into the cylinder chamber and discharged outside the cylinder chamber. In an electric compressor that rotates a rotor with a motor, the rotation angle of the rotor is detected sensorlessly using the induced current flowing through the stator coil of the motor and applied to the stator coil of the motor according to the detected rotation angle of the rotor. Sensorless vector control for adjusting the voltage to be performed is performed.

  However, the induced current flowing through the stator coil at the start of the motor is weak because the amount of rotation of the rotor is small, and may be insufficient to specify the rotation angle of the rotor. Therefore, at the time of starting the motor, the rotor is forcibly rotated by rotating the motor by synchronous control for forcibly moving the pole excited by the stator coil at a constant frequency.

  However, in the synchronous control, if the current flowing through the stator coil is insufficient with respect to the load torque applied to the rotor, the rotor cannot start rotating against the load torque, and the motor may fail to start. is there.

  Therefore, by controlling the energization pattern of the stator coil when stopping the motor, the rotor is finally stopped at a specific rotation angle. When the motor is started, synchronous control is performed with a pattern corresponding to the specific rotation angle. Has been proposed (for example, Patent Document 1).

JP 2006-271179 A

  By the way, a vane rotary type electric motor that changes the protrusion length of each vane from the rotor as the rotor rotates while sliding a plurality of vanes that appear and disappear from the rotor on the inner peripheral surface of the cylinder chamber in which the rotor is accommodated. In the compressor, after the motor is stopped, the rotor rotates in the reverse direction (reverse rotation) due to the differential pressure between the suction side fluid and the discharge side fluid. When the rotational frictional force applied to the rotor exceeds the differential pressure between the suction side fluid and the discharge side fluid, the reverse rotation of the rotor stops.

  For this reason, in the motor of the vane rotary type electric compressor, the above-described control for stopping the rotor at a specific rotation angle is performed when the motor is stopped, and the motor is efficiently matched to the stop position of the rotor when the motor is started. It is difficult to perform synchronous control.

  Therefore, with respect to the motor of the vane rotary type electric compressor, it is preferable to detect the stop position of the rotor after the rotor has stopped and perform synchronous control at the time of starting the motor with a pattern in accordance with the stop position.

  However, all of the currently proposed rotor stop position detections must execute complex algorithm logic, and resources such as processors and memory are required to implement this in actual equipment. It's hard to say realistic because it needs to be big.

  Such a problem is not limited to the electric compressor having the vane rotary type compression mechanism described above, but is common to the electric compressor having the rotary type compression mechanism in which the load torque changes depending on the rotation angle of the rotor.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent the compressor from failing to start because the rotating body of the compression mechanism cannot start rotating against the load torque when the compressor is started. An object of the present invention is to provide a compressor motor control device that can be used, and a suitable electric compressor using the compressor motor control device.

In order to achieve the above object, the present invention provides:
In a motor control device that rotates a rotating shaft connected to a rotating body of a compression mechanism of a compressor in which inhaled gas is compressed,
A current for position detection is applied to the coil of the motor while the motor is stopped, and the orthogonal coordinate system according to the rotation angle of the rotating body is determined based on the position of the stator of the motor from the current flowing through the coil. Shaft current detection means for detecting the shaft current;
An electrical angle detection means for detecting the electrical angle corresponding to the axial current detected by the axial current detection means, based on a table in which the axial current is associated with the electrical angle of the rotor of the motor;
It is characterized by providing.

  According to the present invention, it is possible to prevent the compressor from failing to start because the rotating body of the compression mechanism cannot start rotating against the load torque when the compressor is started.

It is sectional drawing which shows the electric compressor which concerns on one Embodiment of this invention. It is an expanded sectional view of the compression mechanism of FIG. It is explanatory drawing which shows the electrical structure of the electric compressor of FIG. It is a graph which shows the relationship between the rotor rotation angle of the compression mechanism of FIG. 1, and load torque. It is a graph which shows the relationship between the mechanical angle of the rotor of the compression mechanism of FIG. 1, and the rotation angle which a rotor stops by rotational frictional force. It is explanatory drawing which shows the logarithm of the magnetic pole which the rotor of the electric motor of FIG. 1 has. It is a graph which shows the relationship between the mechanical angle of the rotor of the compression mechanism of FIG. 1, the electrical angle of an electric motor, and the rotation angle which a rotor stops by rotational frictional force. The relationship between the current of each axis and the mechanical angle of the rotor when the vector of the current flowing through the coils of each phase of the UVW of the electric motor in FIG. 1 is converted into the α-axis and β-axis orthogonal coordinate systems based on the position of the stator. It is a graph which shows. It is a graph which shows the relationship between each axis | shaft current of (alpha) axis | shaft of FIG. 8, and the electrical angle of an electric motor. It is a graph which shows the relationship between each axial electric current of (alpha) axis | shaft of FIG. 8, and the (beta) axis | shaft, the electrical angle of an electric motor, and the rotation angle which a rotor stops by rotational frictional force. It is explanatory drawing which shows the state of the inverter circuit at the time of energizing the coil of a stator in order for the motor control part of FIG. 3 to detect the electrical angle of an electric motor. It is a graph which shows the relationship between the switching waveform of the motor control part with respect to the inverter circuit of FIG. 11, and the waveform of the electric current which flowed through the coil of the electric motor. It is a graph which shows the alpha-axis current and beta-axis current of the coil of the electric motor calculated | required by the electricity supply which the motor control part of FIG. 3 performed. FIG. 9 is an explanatory diagram showing, for each combination of the number of magnetic pole pairs and the number of vanes of the compression mechanism, that the rotor of FIG. 6 can detect whether the electric angle of the electric motor can be detected from the currents of the α axis and β axis in FIG. 8. . It is a flowchart which shows the procedure of the control which the motor control part of FIG. 3 performs at the time of starting of an electric motor. It is a flowchart which shows the procedure of the starting process of FIG.

  Hereinafter, an embodiment in which the present invention is applied to an electric compressor having a vane rotary type compression mechanism will be described with reference to the drawings.

  FIG. 1 is a front sectional view showing a schematic configuration of an electric compressor according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the compression mechanism of FIG. In the present embodiment, an electric compressor having a vane rotary type compression mechanism having three vanes will be described as an example. An electric compressor 1 according to the present embodiment shown in FIG. 1 compresses a refrigerant by driving a rotary compression mechanism 3 with an electric motor 5.

  The electric compressor 1 (corresponding to the compressor in the claims) includes a compression mechanism 3 and an electric motor 5, a housing 7 in which these are accommodated, and a controller 15.

  The compression mechanism 3 includes a pair of side blocks 3a and 3b, a cylinder block 3c sandwiched between them, and a columnar rotor 3e accommodated in an elliptical cylinder chamber 3d formed inside the cylinder block 3c. doing.

  The rotor 3e (corresponding to the rotating body in the claims) is attached to the rotating shaft 5a of the electric motor 5 supported by the bearing portions 3f, 3g of the side blocks 3a, 3b. As shown in FIG. A vane 33 is supported in each of the three vane grooves 31 opened on the peripheral surface of 3e so as to be able to protrude and retract from the peripheral surface of the rotor 3e. The vane groove 31 and the vane 33 are arranged at intervals of 120 ° in the rotation direction X (forward direction) of the rotor 3e.

  When the rotor 3e is rotated in the rotation direction X (positive direction) in the cylinder chamber 3d by the electric motor 5, each vane 33 of the rotor 3e protrudes and retracts from the vane groove 31 along the inner peripheral surface of the cylinder chamber 3d. The volume of the compression chamber 35 composed of the two vanes 33 adjacent to 3e and the cylinder chamber 3d changes.

  Then, while the volume of the compression chamber 35 increases, a low-pressure refrigerant is sucked through a suction port (not shown) formed in the side block 3 a, and the sucked refrigerant is compressed as the volume of the compression chamber 35 decreases. Is done. The compressed high-pressure refrigerant opens the discharge valve 3m of the discharge port 3l of the cylinder block 3c, and is further discharged from a discharge port (not shown) formed in the side block 3b.

  As shown in FIG. 1, an electric motor 5 (corresponding to a motor in claims) includes a rotor 5b (corresponding to a rotor in claims) attached to a rotating shaft 5a, and a stator disposed outside the rotor 5b. 5c. The stator 5c has teeth (not shown) corresponding to a plurality of poles, and a coil 5d is wound around each tooth. The electric motor 5 rotates the rotor 5b by generating a rotating magnetic field in the stator 5c by applying a voltage in a predetermined pattern to each coil 5d.

  The housing 7 has a cylindrical shape with one end closed. The housing 7 accommodates the compression mechanism 3, and the accommodated compression mechanism 3 exposes the inside of the housing 7 to the closed discharge chamber 7 a on the closed side where the side block 3 b is exposed and the side block 3 a. It is partitioned off from the suction chamber 7b on the opening side. An electric motor 5 is accommodated in the suction chamber 7 b, and the suction chamber 7 b is sealed by a lid portion 9 attached to the opening 7 c of the housing 7.

  The suction chamber 7b described above is a space where the low-temperature and low-pressure refrigerant compressed by the compression mechanism 3 is sucked from the outside of the electric compressor 1 (for example, an evaporator of the refrigeration cycle) through a suction port (not shown).

  Further, the discharge chamber 7a, which is hermetically partitioned from the suction chamber 7b by the compression mechanism 3, allows the high-temperature and high-pressure refrigerant compressed by the compression mechanism 3 to be discharged to the outside of the electric compressor 1 (for example, refrigeration) via a discharge port (not shown). This is the space discharged to the condenser of the cycle. A liquid reservoir 7d for storing the lubricating oil 11 is formed in the lower portion of the discharge chamber 7a. A liquid phase refrigerant (not shown) in the discharge chamber 7a is also retained in the liquid reservoir 7d.

  The lubricating oil 11 in the liquid pool portion 7d is supplied to the bearing portions 3f and 3g of the side blocks 3a and 3b by the pressure of the refrigerant in the discharge chamber 7a, and is used for lubricating the rotating shaft 5a that the bearing portions 3f and 3g support. . The bearing portions 3f and 3g are formed by annular grooves formed on the inner peripheral surface of the through hole through which the rotation shaft 5a of the side blocks 3a and 3b passes.

  The lubricating oil 11 in the liquid reservoir 7d is supplied to the bearing portion 3f of the side block 3a through the passage 3h of the side block 3b, the passage 3i of the cylinder block 3c, and the passage 3j of the side block 3a. The lubricating oil 11 in the liquid reservoir 7d is supplied to the bearing portion 3g of the side block 3b through the passage 3k of the side block 3b.

  The lubricating oil 11 supplied to the bearing portions 3f and 3g of the side blocks 3a and 3b flows into the suction chamber 7b through a gap with the rotating shaft 5a and accumulates at the bottom of the suction chamber 7b. The liquid-phase refrigerant sucked into the suction chamber 7b also collects at the bottom of the suction chamber 7b. Lubricating oil 11 and liquid-phase refrigerant accumulated at the bottom of the suction chamber 7b ride on the refrigerant flow in the suction chamber 7b and are sucked into the cylinder chamber 3d of the compression mechanism 3, where they are mixed with the compressed high-pressure refrigerant. It is discharged into the discharge chamber 7a.

  Therefore, the discharge chamber 7a is provided with an oil separator 7e that separates the lubricating oil 11 from the high-pressure refrigerant. The lubricating oil 11 separated from the refrigerant by the oil separator 7e is retained in the liquid reservoir 7d at the lower part of the discharge chamber 7a together with the liquid-phase refrigerant (not shown) in the discharge chamber 7a.

  The controller 15 (corresponding to the control device and the compressor motor control device in the claims) has an inverter circuit 15a and a motor control unit 15b as shown in the explanatory diagram of FIG.

  The inverter circuit 15 a converts the electric power of the DC power supply 13 into AC and supplies it to the U, V, W phase coils 5 d of the stator 5 c of the electric motor 5. The inverter circuit 15a includes IGBTs (Insulated Gate Bipolar Transistors) Q1 to Q6 as power switching elements for the upper arm and the lower arm corresponding to the coils 5d of each phase.

  The IGBTs Q1 to Q6 may be replaced with power transistors such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors).

  The motor control unit 15b (corresponding to the shaft current detection means, the electrical angle detection means, and the activation control means in the claims) applies to each coil 5d according to a predetermined pattern for generating a rotating magnetic field in the stator 5c of the electric motor 5. For controlling voltage application, for example, a microcomputer is used.

  The motor control unit 15b performs voltage application to each coil 5d by sensorless vector control in a steady period after the rotor 5b reaches a constant rotational speed. In sensorless vector control, the rotation angle of the rotor 5b is specified sensorlessly using the induced current or voltage flowing through the non-excited phase coil 5d of the stator 5c, and the rotating magnetic field rotates in accordance with the rotation angle of the rotor 5b. Thus, a voltage is applied to each coil 5d.

  On the other hand, since the induced current or voltage flowing through the coil 5d of the stator 5c is small during the start-up period from when the rotor 5b starts to reach a certain rotational speed, the rotation angle of the rotor 5b is specified using this. I can't. Accordingly, the motor control unit 15b performs voltage application to each coil 5d by synchronous control (synchronous operation) during the start-up period. In the synchronous control, a voltage is applied to each coil 5d so that the rotor 5b whose rotation angle is unknown rotates in synchronization with the rotation of the rotating magnetic field generated in the stator 5c.

  During synchronous control, the motor control unit 15b applies a voltage to the coils 5d of the U, V, and W phases of the stator 5c so that a torque exceeding the starting torque of the rotor 3e of the compression mechanism 3 is generated. It is necessary to prevent the electric compressor 1 from starting up.

  Incidentally, as shown in the graph of FIG. 4, the load torque of the rotor 3e varies depending on the rotation angle of the rotor 3e. The reason why the load torque varies depending on the rotation angle of the rotor 3e is that the volume of the compression chamber 35 between the two adjacent vanes 33, 33 in the cylinder chamber 3d changes with the rotation of the rotor 3e, and the refrigerant in the compression chamber 35 This is because the pressure increases due to compression.

  That is, at the rotation angle of the rotor 3e when the refrigerant is sucked into the compression chamber 35, the load torque of the rotor 3e is low because the refrigerant pressure in the compression chamber 35 is low. On the other hand, at the rotation angle of the rotor 3e when the sucked refrigerant is compressed to the point of discharge in the compression chamber 35, the load torque of the rotor 3e is high because the refrigerant pressure in the compression chamber 35 is high. For this reason, the fluctuation of the load torque of the rotor 3e fluctuates at a period interlocked with the rotation of the rotor 3e.

  Therefore, the rotation angle at which the rotor 3e is stopped by the stop of the electric motor 5 is specified, and the coil 5d of each phase of the stator 5c of the electric motor 5 is activated when the electric compressor 1 is started according to the load torque corresponding to the rotation angle. It is desirable to adjust the voltage to be applied.

  By the way, when the electric motor 5 is stopped, the rotor 3e rotates in the reverse direction (reverse rotation) by the differential pressure between the refrigerant pressure in the discharge chamber 7a and the refrigerant pressure in the suction chamber 7b. When the rotational friction force applied to the rotor 3e due to the sliding of the vane 33 with respect to the inner peripheral surface of the cylinder chamber 3d exceeds the differential pressure between the refrigerant pressure in the discharge chamber 7a and the refrigerant pressure in the suction chamber 7b, the rotor 3e. Reverse rotation of stops.

  In the electric compressor 1 of the present embodiment, the three vanes 33 protruding from the three vane grooves 35 formed on the peripheral surface of the rotor 3e at intervals of 120 ° slide on the inner peripheral surface of the cylinder chamber 3d. For this reason, as shown in the graph of FIG. 5, there are three positions where the rotor 3e, which has rotated in reverse after the electric motor 5 stops, is stopped at intervals of 120 ° during one rotation of the rotor 3e.

  Therefore, in the electric compressor 1 of the present embodiment, when the electric motor 5 is started, the motor control unit 15b in FIG. 3 determines which of the three locations shown in FIG. 5 the rotor 3e of the compression mechanism 3 is through the rotation angle of the rotor 5b. It is detected whether the rotation angle is stopped, and a synchronous operation is performed in which a current corresponding to the rotation angle is supplied to the coil 5d of the stator 5c.

  As a method for detecting the rotation angle of the rotor 5b, it is detected from the current that actually flows through the coil 5d when the rotor 5b of the electric motor 5 energizes the coils 5d of the U, V, and W phases of the stator 5c. It is conceivable to use the electrical angle of the electric motor 5.

  Here, the electrical angle of the electric motor 5 is an angle obtained by multiplying the rotation angle of the rotor 5b by the number of magnetic pole pairs (number of pole pairs) formed by the permanent magnets of the rotor 5b. In the present embodiment, as shown in the explanatory diagram of FIG. 6, the rotor 5 b has two pairs of the S pole and the N pole, and therefore, with respect to the rotation angle of the rotor 5 b having two pole pairs. The electrical angle of the electric motor 5 is twice as shown in the graph of FIG.

  By the way, when the electric angle of the electric motor 5 is obtained from the current flowing through the coil 5d of the stator 5c, the orthogonal coordinate system (α (Axis, β axis) vector.

  The currents (α-axis current iα, β-axis current iβ) in the orthogonal coordinate system after the coordinate conversion change at a cycle twice the electrical angle of the electric motor 5 as shown in the graph of FIG. Such a change is significant when the electric motor 5 is an IPM motor using an interior permanent magnet (IPM) rotor 5b in which a permanent magnet is embedded as shown in FIG. Become. This is because the motor torque of the electric motor 5 is a combination of the magnet torque and the reluctance torque.

  Even in an SPM motor using a surface permanent magnet (SPM) rotor 5b with a permanent magnet exposed on the surface, the motor torque includes a slight reluctance torque. For this reason, even when the electric motor 5 is an SPM motor, although the amplitude is smaller than the change shown in the graph of FIG. 8, the α-axis current iα and the β-axis current iβ periodically change.

  Then, since the α-axis current iα and the β-axis current iβ fluctuate at a cycle twice the electrical angle of the electric motor 5, for example, as shown in the graph of FIG. 9, the α-axis current iα and the β-axis current iβ The electric angles of the electric motor 5 corresponding to the A point and the B point, respectively, having the same value are 100 ° and 280 °. In this case, the mechanical angle of the rotor 5b cannot be specified by the electrical angle of the electric motor 5 obtained from the α-axis current iα and the β-axis current iβ.

  As described above, when there are a plurality of mechanical angles of the rotor 5b specified from the electrical angle of the electric motor 5, several methods have been proposed for obtaining a correct mechanical angle from them. However, in any case, complex algorithm logic must be executed, and in order to realize this with an actual device, it is necessary to increase the resources such as the processor and memory. It's hard to say.

  On the other hand, at the electrical angles corresponding to the three rotational angles at which the rotor 3e of the compression mechanism 3 stops due to the rotational friction force, the values of the α-axis current iα and the β-axis current iβ corresponding to each electrical angle are C, Like each point of D and E, it becomes a combination of different values.

  Therefore, the electrical angle of the electric motor 5 can be obtained from the combination of the values of the α-axis current iα and the β-axis current iβ, and the mechanical angle of the rotor 5b can be specified.

  Therefore, in the electric compressor 1 of the present embodiment, before starting the electric motor 5, the motor control unit 15b detects the electric angle of the electric motor 5 for such a short time that the rotor 5b does not rotate. Energization is performed on the coils 5d of each phase of the stator 5c.

  In this energization, for example, a single shunt method is used, and a pulse signal shown at the top of the graph of FIG. 12 for turning on the IGBTs Q1, Q5, and Q6 of the inverter circuit 15a with a pattern shown in the explanatory diagram of FIG. The unit 15b outputs. Accordingly, when the current (iu, iv, iw) having the waveform shown in the lower part of the graph of FIG. 12 flows through the coils 5d of the U, V, W phases of the stator 5c, the current (iu, iv, iw) The motor control unit 15b obtains the values of the α-axis current iα and the β-axis current iβ using the conversion formula shown in FIG.

  Then, the motor control unit 15b includes the electric motor 5 in which the combination of the α-axis current iα and the β-axis current iβ stored in advance in a memory (not shown) and the rotor 3e of the compression mechanism 3 are stopped by the rotational friction force. With reference to the table 15c in FIG. 3 in which the electrical angle is associated, the electrical angle of the electric motor 5 corresponding to the combination of the α-axis current iα and the β-axis current iβ determined by the motor control unit 15b is specified.

  Here, if the combination of the values of the α-axis current iα and the β-axis current iβ is the value of the α-axis current iα and the β-axis current iβ at the point a in the graph of FIG. 13, the motor control unit 15b It is confirmed whether or not the electrical angle of the electric motor 5 corresponding to the combination of values is defined in the table 15c of FIG.

  Then, the motor control unit 15b activates the electric motor 5 when the electrical angle of the electric motor 5 corresponding to the combination of the values of the α-axis current iα and the β-axis current iβ is defined in the table 15c of FIG. At this time, the synchronous operation is performed so that a current having a magnitude that generates a torque exceeding the starting torque of the rotor 3e flows through the coil 5d of the stator 5c.

  For example, when the electrical angle of the electric motor 5 corresponding to the combination of the values of the α-axis current iα and the β-axis current iβ obtained with reference to the table 15c is the C point in FIG. 10, the motor control unit 15b Synchronous operation is performed so that a current of a magnitude that causes the rotor 3e to generate a torque exceeding the starting torque in flows through the coil 5d of the stator 5c.

  Thereby, the rotor 3e (the rotor 5b of the electric motor 5) can be sufficiently forcibly rotated by the torque generated in the electric motor 5 at the time of starting by the synchronous operation, and the electric compressor 1 can be started without failure.

  Here, when the rotor 3e of the compression mechanism 3 is at three rotational angles at which the rotor 3e is stopped by the rotational friction force, the α-axis current iα and the β-axis current iβ respectively corresponding to the electrical angles of the electric motor 5 are As shown in the explanatory diagram of FIG. 14, when the counter electrode number of the rotor 5 b of the electric motor 5 is “2” and the number of vanes 33 is one of three, five, or seven, All are combinations of different values.

  Therefore, even when the number of counter electrodes of the rotor 5b is “2” and the number of vanes 33 is five or seven, the rotor of the compression mechanism 3 is activated at the time of startup by the synchronous operation in the above-described procedure. It is possible to cause the motor control unit 15b to perform a process for causing the electric motor 5 to generate a torque exceeding the starting torque of 3e.

  When the number of vanes 33 is one, there is only one rotational position of the rotor 3e that is stopped by the rotational friction force, so the mechanical angle of the rotor 3e is specified from the electrical angle of the electric motor 5. There is no need.

  Further, when the counter electrode number of the rotor 3e is an integral multiple of the number of vanes 33, the cycle of the rotational position of the rotor 3e stopped by the rotational friction force coincides with the variation cycle of the electric angle of the electric motor 5, so that the electric motor It is not necessary to specify the mechanical angle of the rotor 3e from the electrical angle of 5.

  In other cases, the α-axis current iα and the β-axis current iβ corresponding to each electrical angle of the electric motor 5 are the same when the rotor 3e of the compression mechanism 3 is at each rotation angle stopped by the rotational friction force. Since the value may be a value, the mechanical angle of the rotor 3 e cannot be specified from the electrical angle of the electric motor 5.

  The motor control unit 15b performs the control described above when the electric motor 5 is rotated by synchronous control prior to sensorless control as the electric compressor 1 is started. Hereinafter, a procedure of processing until the motor control unit 15b shifts the control of the electric motor 5 from the synchronous control to the sensorless control will be described with reference to the flowcharts of FIGS. 15 and 16.

  First, as shown in FIG. 15, the motor control unit 15 b performs a startup process of the electric compressor 1 in response to a startup command (step S <b> 1). In this start-up process, as shown in FIG. 16, the motor control unit 15b shortens the energization for detecting the electric angle of the electric motor 5 to the coils 5d of the U, V, and W phases of the stator 5c. Perform time (step S11).

  Next, the motor control unit 15b obtains the α-axis current iα and the β-axis current iβ from the currents (iu, iv, iw) flowing through the coils 5d of the respective phases using the conversion formula shown in FIG. 12 (step S13). Further, the electrical angle of the electric motor 5 is obtained with reference to the table 15c of FIG. 3 (step S15).

  Then, the current to be applied to the coils 5d of each phase of the electric motor 5 such that a torque exceeding the starting torque of the rotor 3e having a rotation angle corresponding to the electric angle of the electric motor 5 obtained in step S15 is generated in the rotor 3e. The size is determined (step S17), the activation process is terminated, and the process returns to the flowchart of FIG.

  After the start-up process in step S1 shown in FIG. 15, the motor control unit 15b starts the forced commutation operation of the electric motor 5 by the synchronous control in which the current having the magnitude determined in step S1 is caused to flow in the coils 5d of each phase. Then (step S3), the electric motor 5 is accelerated by increasing the command speed for control (step S5).

  Then, the motor control unit 15b has an induction current sufficient to detect the rotation angle of the rotor 5b in the coil 5d of the phase other than the excitation phase based on the control command speed and the like. It is confirmed whether or not a predetermined speed is reached (step S7). If the predetermined speed has not been reached (NO in step S7), the process returns to step S5. If the predetermined speed has been reached (YES in step S7), the motor control unit 15b proceeds to sensorless spectrum control. (Step S13) The current value and the phase flowing through the excitation phase coil 5d at the determined pace are changed to the target current value and the target current phase.

  Thus, according to the controller 15 of the present embodiment, when the electric motor 5 is started by synchronous control, a short-time current is caused to flow through the coils 5d of each phase of the stator 5c, and the coils 5d of each phase are flowed. The α-axis current iα and β-axis current iβ are obtained from the currents (iu, iv, iw), and the electrical angle of the electric motor 5 is obtained from the combination of the values with reference to the table 15c.

  And when starting the electric motor 5 by synchronous control, the electric current which generate | occur | produces the torque exceeding the starting torque of the rotor 3e of the rotation angle corresponding to the calculated | required electrical angle was made to flow into the coil 5d of each phase.

  For this reason, when starting the electric motor 5, the rotor 3e (the rotor 5b of the electric motor 5) can be sufficiently forcibly rotated by the torque generated in the electric motor 5 at the time of starting by synchronous operation, and the electric compressor 1 fails. Can be started without.

  In the present embodiment, the case where the present invention is applied to the electric compressor 1 having the vane rotary type compression mechanism 3 that rotates the rotor 3e in the cylinder chamber 3d has been described as an example. However, the present invention has a rotary compression mechanism that sucks and compresses gas by rotating a rotating body, such as a scroll compressor that rotates a movable scroll with respect to a fixed scroll to compress gas. This is widely applicable when the compressor is rotated by a motor.

  The present invention can be used in an electric compressor in which a refrigerant compression mechanism is driven by an electric motor.

1 Electric compressor (compressor)
3 Compression mechanism 3a, 3b Side block 3c Cylinder block 3d Cylinder chamber 3e Rotor (rotating body)
3f, 3g Bearing part 3h, 3i, 3j, 3k Passage 3l Discharge port 3m Discharge valve 5 Electric motor (motor)
5a Rotating shaft 5b Rotor (rotor)
5c Stator 5d Coil 7 Housing 7a Discharge chamber 7b Suction chamber 7c Opening 7d Oil reservoir 7e Oil separator 9 Lid 11 Lubricating oil 13 DC power supply 15 Controller (control device, compressor motor control device)
15a Inverter circuit 15b Motor controller (shaft current detection means, electrical angle detection means, start-up control means)
15c table 31 vane groove 33 vane 35 compression chamber iα α-axis current iβ β-axis current Q1 to Q6 IGBT
X direction of rotation

Claims (3)

In the control device (15) of the motor (5) for rotating the rotating shaft (5a) connected to the rotating body (3e) of the compression mechanism (3) of the compressor (1) in which the sucked gas is compressed,
While the motor (5) is stopped, the coil (5d) of the motor (5) is energized with a position detection current, and the stator (5c) of the motor (5) is obtained from the current flowing through the coil (5d). An axis current detection means (15b) for detecting an axis current (iα, iβ) of an orthogonal coordinate system according to the rotation angle of the rotating body (3e) with reference to the position of
The shaft current (iα, iβ) detected by the shaft current detection means (15b) based on a table in which the shaft current (iα, iβ) is associated with the electrical angle of the rotor (5b) of the motor (5). Electrical angle detection means (15b) for detecting the electrical angle corresponding to
A compressor motor control device (15) comprising:   The start control means (15b) for starting the motor (5) by energizing the coil (5d) in a pattern for generating a maximum torque in the rotor (5b) having the electrical angle. The compressor motor control device (15) as described. Between the vanes (33) projecting from a plurality of positions at equal intervals in the rotation direction (X) of the rotating body (3e) rotating in the cylinder chamber (3d) and slidingly contacting the inner peripheral surface of the cylinder chamber (3d) A compression mechanism (3) in which the gas sucked into the cylinder chamber (3d) is compressed,
A motor (5) for rotating a rotating shaft (5a) connected to the rotating body (3e);
A control device (15) for controlling the motor (5),
The number of pole pairs of the rotor (5b) of the motor (5) is two;
The number of the vanes (33) is one of three, five and seven;
The compressor motor control device (15) according to claim 1 or 2 is used as the control device (15).
The electric compressor (1) characterized by the above-mentioned.

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