JP2015186318A - Control device for electrically-driven compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an electrically-driven compressor capable of suppressing power consumption without requiring a large memory capacity.SOLUTION: A control device for a vane rotary type electrically-driven compressor including a rotor that is rotated and driven by a motor 2 includes: a motor driving section 5 for generating a motor drive signal; and a motor drive control device 4 for generating a control signal of the motor driving section. The motor drive control device includes: a memory 11 storing a table associating a stop command angle representing an angle of the rotor in the case where a stop command of the motor is outputted, an estimated stop angle indicating an estimated stop angle of the rotor and a current phase command instructing such a current phase that a difference from the estimated stop angle becomes a predetermined value; and a control section 12 which estimates a stop position of the rotor by acquiring from the table the estimated stop angle corresponding to the stop command angle on the basis of the motor drive signal, acquires from the table the current phase command corresponding to the stop position, generates such a control signal that maximum torque of the motor is outputted, and supplies the control signal to the motor driving section.

Description

  The present invention relates to a control device for an electric compressor that compresses gas.

  When starting an electric compressor by sensorless control, a synchronous operation process (process which estimates the angle of a rotor) is needed beforehand. In the synchronous operation process, it is necessary to generate a rotating magnetic field to rotate the rotor and to rotate the motor to a speed at which the angle can be estimated.

  In such an electric compressor, at the time of start-up, a motor torque sufficient to overcome the differential pressure between the discharge side and the suction side in the electric compressor is required, and if the torque is insufficient, the start-up may fail. Therefore, in order to obtain a high torque, it is necessary to supply a current having a current phase that can output the maximum torque to the motor. For this reason, it is necessary to estimate the angle of the rotor when the motor is stopped by some method.

  As a method of this estimation, conventionally, a current is supplied to a specific phase and positioning is performed by attracting the rotor to a specific position, and a current phase current that generates a maximum torque with respect to the positioned angle is supplied. A method is known in which an initial position is estimated by some algorithm by passing an electric current in advance, and an electric current is supplied at a current phase at which a maximum torque is generated with respect to the estimated angle (Patent Document 1).

JP 2006-271179 A (FIG. 6)

  However, in order to estimate the initial position described above, there is a problem that a large memory capacity is required because a theoretical formula or a complicated algorithm is required. In addition, there is a problem in that power consumption increases in a method in which a current is passed before startup for estimation of the initial position.

  An object of the present invention is to provide a control device for an electric compressor that does not require a large memory capacity and can suppress power consumption.

  In the case of a vane rotary type electric compressor, the stop angle of the rotor is limited by the combination of the number of vanes and the number of compression chambers. Therefore, in the present invention, the rotor angle during sensorless control is monitored, and the rotor stop angle is estimated from the rotor angle when the motor stop command is issued.

  That is, the present invention provides a control device for a vane rotary type electric compressor including a rotor that is rotationally driven by a motor, a motor drive unit that generates a motor drive signal for driving the motor, and a A motor drive control device that generates a control signal for controlling the motor drive unit based on the motor drive signal, and the motor drive control device represents the angle of the rotor when the motor stop command is issued. A memory that stores a table in which a stop command angle, an estimated stop angle that estimates the angle at which the rotor stops, and a current phase command that indicates a current phase at which a difference between the estimated stop angle is a predetermined value; The estimated stop angle corresponding to the stop command angle calculated based on the motor drive signal from the motor drive unit is stored in the table stored in the memory. Obtaining and estimating the stop position of the rotor, obtaining a current phase command corresponding to the estimated stop position from the table, generating a control signal for generating a maximum torque of the motor based on the obtained current phase command, And a control unit that supplies the motor drive unit.

  According to the present invention, since the stop position of the rotor can be easily estimated, an algorithm for positioning control becomes unnecessary, and the memory capacity can be reduced. In addition, since it is not necessary to pass a current in order to estimate the initial position, power consumption can be suppressed.

It is a block diagram which shows the structure of the control apparatus of the electric compressor of embodiment of this invention. It is a figure which shows the example of the table used with the control apparatus of the electric compressor of embodiment of this invention. It is a figure which shows the relationship between the current phase used for the setting of the current phase command of the table shown in FIG. 2, and a rotor angle. It is a figure which shows the relationship between the phase difference of the electric current phase and rotor angle in the motor control apparatus of the electric compressor of embodiment of this invention, and the output torque. It is a figure which shows these waveforms in case the phase difference of a rotor angle and an electric current phase is 0 degree in the motor control apparatus of the electric compressor of embodiment of this invention. In the motor control apparatus of the electric compressor of the embodiment of the present invention, it is a diagram showing these waveforms when the phase difference between the rotor angle and the current phase is 40 °. It is a figure for demonstrating stop control in case the stop angle is A [deg] in the motor control apparatus of the electric compressor of embodiment of this invention. It is a figure for demonstrating stop control in case the stop angle is B [deg] in the motor control apparatus of the electric compressor of embodiment of this invention. It is a figure for demonstrating stop control in case the stop angle is C [deg] in the motor control apparatus of the electric compressor of embodiment of this invention.

  Hereinafter, a control device for an electric compressor according to an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an electric compressor control apparatus according to an embodiment of the present invention. The electric compressor controlled by this electric compressor control device includes an inverter 1, a motor 2 and a compressor 3.

  The inverter 1 converts a direct current supplied from a direct current power source into an alternating current and supplies the alternating current to the motor 2. The inverter 1 includes a motor drive control device 4 and a motor drive unit 5. The motor 2 is composed of a three-phase AC motor, and is driven by the AC current from the inverter 1 to drive the compressor 3.

  The compressor 3 includes a rotor (not shown), and this rotor is directly connected to the motor 2 and is driven to rotate. The compressor 3 compresses the low-pressure refrigerant sucked by the rotation of the rotor, converts it into a high-pressure refrigerant, and discharges it.

  The motor drive unit 5 included in the inverter 1 includes a first series circuit composed of a high-side switching element Uh and a low-side switching element Ul, and a second series circuit composed of a high-side switching element Vh and a low-side switching element Vl. , And a third series circuit composed of a high-side switching element Wh and a low-side switching element Wl is connected in parallel.

  Each of the switching elements Uh, Vh, Wh, Ul, Vl and Wl is composed of an IGBT (insulated gate bipolar transistor). A diode is connected in antiparallel between the collector and emitter of each of the switching elements Uh, Vh, Wh, Ul, Vl and Wl.

  One end of the high-side switching element Uh, one end of the high-side switching element Vh, and one end of the high-side switching element Wh are connected to the positive electrode of the DC power supply and one end of the capacitor C1. One end of the low-side switching element Ul, one end of the low-side switching element Vl, and one end of the low-side switching element Wl are connected to the negative electrode of the DC power supply and the other end of the capacitor C1.

  The other end of the high-side switching element Uh and the other end of the low-side switching element Ul are connected to the U phase of the motor 2. The other end of the high-side switching element Vh and the other end of the low-side switching element Vl are connected to the V phase of the motor 2. The other end of the high-side switching element Wh and the other end of the low-side switching element Wl are connected to the W phase of the motor 2.

  The motor drive unit 5 turns on / off the six switching elements Uh, Ul, Vh, Vl, Wh, and Wl in accordance with control signals G1 to G6 from the motor drive control device 4, thereby causing a direct current from the direct current power source. Is converted into a three-phase alternating current and supplied to the motor 2 to drive the motor 2. The motor 2 is composed of a synchronous motor, and is driven to rotate by a three-phase alternating current from the motor drive unit 5 to drive the compressor 3.

  The motor drive control device 4 included in the inverter 1 is composed of, for example, a microcomputer (MCU) and is connected to the motor drive unit 5. During normal operation, the motor drive control device 4 detects a motor drive signal including a signal indicating the voltage and current of each phase of the U phase, V phase, and W phase of the motor 2, and based on the motor drive signal of each phase. The position (angle) of the rotor is calculated. Then, based on the calculated rotor position, six control signals G1, G2, G3, G4, G5 and G6 for controlling the six switching elements Uh, Ul, Vh, Vl, Wh and Wl are generated. The generated control signals G1, G2, G3, G4, G5 and G6 are applied to the gates of the six switching elements Uh, Ul, Vh, Vl, Wh and Wl. Thereby, the six switching elements Uh, Ul, Vh, Vl, Wh, Wl are turned on / off.

  The motor drive control device 4 includes a memory 11 and a control unit 12. The memory 11 stores a table that stores information for driving the motor 2. The control unit 12 generates the control signals G <b> 1 to G <b> 6 described above based on the motor drive signal of each phase from the motor drive unit 5 and information read from the table of the memory 11.

  As shown in FIG. 2, the memory 11 includes a stop command angle that represents the angle of the rotor when a stop command for the motor 2 is issued, an estimated stop angle that estimates the angle at which the rotor stops, and an estimated stop angle. A table in which a current phase command that indicates a current phase at which the difference becomes a predetermined value is associated is stored. By referring to this table, the estimated stop angle of the motor 2 is estimated, and a current phase command corresponding to the estimated stop angle is generated.

  The current phase command is set so that the difference between the current phase and the estimated stop angle is 40 °. FIG. 3 is a diagram illustrating the relationship between the current phase and the rotor angle (estimated stop angle). The table shows that the current phase at the point where the alternating current zero-crosses in the negative direction is 0 °, and when the estimated stop angle is A (eg 60 °), the current phase α is 100 ° and the estimated stop angle is B (eg 180 °). Is set such that the current phase β is 220 ° and the estimated stop angle is C (eg, 340 °), the current phase γ is 340 °.

  The control unit 12 selects a current phase command corresponding to the estimated stop angle of the motor 2 with reference to the table in the memory 11 shown in FIG. Then, control signals G1 to G6 for driving the motor 2 are generated based on the selected current phase command and supplied to the gates of the six switching elements Q1 to Q6.

  FIG. 4 shows the relationship between the phase difference between the current phase and the rotor angle and the output torque. For example, if the phase difference is 0 ° (position of the point P1), the rotor angle and the current phase have waveforms as shown in FIG. 5, and the torque is about 2 Nm. If the phase difference is 40 ° (position of the point P2), the rotor angle and the current phase have waveforms as shown in FIG. 6, and the torque is about 3 Nm.

  Next, the operation of the control device for the electric compressor of the embodiment configured as described above will be described with reference to FIGS.

  An electric compressor normally operates as follows. That is, when the operation start command for the electric compressor is output and the synchronous operation is started, the motor drive unit 5 is controlled by the control signals G1 to G6 from the motor drive control device 4, and the motor 2 is driven by the AC power from the inverter 1. Is rotated. Thereby, the compressor 3 is driven and the low-pressure refrigerant enters the compressor 3. In the compressor 3, the rotor rotates to compress the low-pressure refrigerant and send the high-pressure refrigerant to the discharge side, and the electric compressor is operated.

  Next, a characteristic operation of the control device for the electric compressor according to the embodiment will be described. FIG. 7 shows the state of stop control when the stop angle is A [deg] (for example, 60 °). During normal sensorless control, the rotor angle can be calculated based on the U-phase, V-phase, and W-phase motor drive signals supplied from the motor drive unit 5 to the motor 2, so that the rotor angle can be monitored.

In the vane rotary type electric compressor, the compression is performed by the number of times corresponding to the number of vanes during one rotation of the rotor (while the rotor mechanical angle changes from 0 ° to 360 °). As shown in FIG. 2, pulsation (ripple) of load torque occurs.
FIG. 7 shows an example in which compression is performed three times during one rotation of the rotor. Here, the present inventors have confirmed by experiments that the rotor stops at any valley position of the pulsating load torque.

  In this embodiment, the relationship between the angle when the switching stop command for the inverter 1 is issued (stop command angle) and the angle of the stop position (estimated stop angle) is stored in advance in the table shown in FIG. Thus, the stop angle is estimated. The switching stop command for the inverter 1 has the same meaning as the stop command for the motor 2.

  For example, when a switching stop command for the inverter 1 is issued in the angle range indicated by “W” in FIG. 7A, the motor output torque changes so as to be smaller than the load torque as shown in FIG. 7B. The rotor is considered to stop between the next load torque peak and the previous load torque peak.

  For this reason, when a switching stop command is issued in the angle range indicated by W, it can be estimated that the rotor is stopped at the angle A. At the next start-up, referring to the table shown in FIG. 2, the start-up is performed with the maximum torque by giving the motor drive unit 5 a current phase command for generating the maximum torque with respect to the stopped angle A. In FIG. 7C, only the current waveform for one phase is shown, but actually, currents whose phases are shifted by 120 ° and 240 ° simultaneously flow.

  FIG. 8 shows the state of stop control when the stop angle is B [deg] (for example, 180 °). In this electric compressor, as shown in FIG. 8B, pulsation (ripple) of load torque occurs.

  In this embodiment, the stop angle is estimated by referring to the table shown in FIG. For example, when a switching stop command for the inverter 1 is issued in the angle range indicated by “X” in FIG. 8A, the motor output torque changes so as to be smaller than the load torque as shown in FIG. 8B. The rotor is considered to stop between the next load torque peak and the previous load torque peak.

  For this reason, when the switching stop command is issued in the angle range indicated by X, it is estimated that the rotor is stopped at the angle B. At the next start-up, referring to the table shown in FIG. 2, the start-up is performed with the maximum torque by giving the motor drive unit 5 a current phase command for generating the maximum torque with respect to the stopped angle B.

  FIG. 9 shows the state of stop control when the stop angle is C [deg] (for example, 300 °). In this electric compressor, pulsation (ripple) of load torque occurs as shown in FIG.

  In this embodiment, the stop angle is estimated by referring to the table shown in FIG. For example, when a switching stop command for the inverter 1 is issued in the angle range indicated by “Y” in FIG. 9A, the motor output torque changes so as to be smaller than the load torque as shown in FIG. 9B. The rotor is considered to stop between the next load torque peak and the previous load torque peak.

  For this reason, when the switching stop command is issued in the angle range indicated by Y, it is estimated that the rotor is stopped at the angle C. At the next start-up, referring to the table shown in FIG. 2, the start-up is performed with the maximum torque by giving the motor drive unit 5 a current phase command for generating the maximum torque with respect to the stopped angle C.

  The embodiment can be modified as follows. That is, if you want to stop the rotor at the same angle each time, do not stop immediately after the switching stop command for the inverter 1 is issued, but execute the switching stop command for the inverter 1 when the rotor rotates to the angle range you want to stop. To be configured.

  For example, when it is desired to stop at the angle A in FIG. 7, when the rotation angle enters the range of W, a switching stop command is executed. There is a delay between when the stop command is issued by the user and when the switching stop command for the electric compressor is actually executed. However, assuming that the operating rotational speed at this time is 10 rps, there is only a delay of about 100 msec. Therefore, it is considered that there is no problem in actual use.

  As described above, according to the control device for the electric compressor of the embodiment, the rotor stop position can be estimated by a simple process, so that an algorithm for positioning control becomes unnecessary, and the memory capacity can be reduced. In addition, since it is not necessary to flow current to set the initial position, power consumption can be suppressed.

  The present invention is applicable to various electric compressors of a vane rotary type.

DESCRIPTION OF SYMBOLS 1 Inverter 2 Motor 3 Compressor 4 Motor drive control apparatus 5 Motor drive part 11 Memory 12 Control part

Claims (3)

In a control device for a vane rotary type electric compressor including a rotor rotated by a motor (2),
A motor drive unit (5) for generating a motor drive signal for driving the motor;
A motor drive control device (4) for generating a control signal for controlling the motor drive unit based on a motor drive signal from the motor drive unit;
The motor drive control device (4)
A stop command angle that represents the angle of the rotor when the motor stop command is issued, an estimated stop angle that estimates the angle at which the rotor stops, and a current phase at which a difference between the estimated stop angle is a predetermined value. A memory (11) storing a table associating a current phase command to be instructed;
The estimated stop angle corresponding to the stop command angle calculated based on the motor drive signal from the motor drive unit is obtained from the table stored in the memory, the stop position of the rotor is estimated, and the estimated stop position is corresponded A control unit (12) that acquires a current phase command from the table, generates a control signal for generating a maximum torque of the motor based on the acquired current phase command, and supplies the control signal to the motor driving unit;
A control apparatus for an electric compressor, comprising:   2. The control device for an electric compressor according to claim 1, wherein the estimated stop angle stored in the table is an angle of a rotor corresponding to a valley of load torque that pulsates.   2. The electric compressor according to claim 1, wherein when the motor stop command is issued, the control unit delays execution of the stop command so that the rotor stops at a predetermined angle. 3. Control device.

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