JP2010183698A - Motor controller and compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller which prevents damage of the motor controller and a motor by detecting a connection error and its type before the operation of the controller at the beginning of start-up when a connection error occurs in an output signal line of a current detector, and to provide a compressor. <P>SOLUTION: The motor controller is provided with: a power converter 10 changing power into three-phase AC of a variable frequency to be supplied to a three-phase motor; a current detector 30 detecting the conduction currents of a plurality of phases of the motor; and a control part 15 supplying a control signal to the power converter 10 based on an external command signal and a detecting signal of the current detector and emitting a DC command to supply a DC command current for positioning the motor 2 from the power converter at the beginning of the start-up. The control part is also provided with a determination unit determining whether connection of the current detector is correct or not based on a pattern of the detecting signal of the current detector when DC for positioning is supplied. The determination unit generates an interruption signal interrupting the power to be supplied to the power converter when an error is detected. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for detecting a connection state of a motor control device and a current detector of a compressor.

  Patent Documents 1 and 2 disclose techniques relating to the confirmation of the electrical connection of the inverter. In Patent Document 1, the connection between the inverter and the motor or the connection between the power source and the inverter is determined by whether the smoothing capacitor is operated once when receiving low power and the current from the inverter to the motor is detected. Patent Document 2 determines that an abnormality occurs when a detection current for detecting energization from the inverter to the motor is equal to or less than a set value when the inverter is in an operating state. In any case, energization to the motor is detected in the operation state of the inverter.

Japanese Patent Laying-Open No. 2005-081900 JP-A-9-70177

  In a motor control device that controls a three-phase motor having a current detector that detects energization from the inverter to the motor, in a motor control device having a relatively small capacity, the current detector may be mounted on a printed circuit board by soldering. Many. However, in a motor control device with a relatively large capacity, since there are multiple boards, the output signal line of the current detector is connected to the cable via the connector for reasons of assembly work efficiency and maintenance work efficiency. May be connected by.

  In such a configuration, the output signal line cable of the current detector is not connected due to factors such as human error when assembling after disassembling the device once in assembly work during manufacturing or maintenance after installation, Or the case where it becomes a reverse connection can be considered.

  When such a situation occurs, the output current supplied to the motor from the motor control device such as an inverter cannot be detected. Therefore, when the current detector information is used in the motor control algorithm, the motor control device operates. There is a problem that the motor does not rotate despite being in a state.

  Furthermore, when the current controller is mounted in the motor control device as in Patent Document 1 and Patent Document 2, the current command value and the current detection value (zero) do not match (the current command value is 0). Therefore, the current controller raises the command value to the maximum value that can be output in order to match the current detection value with the current command value, and converts the abnormally excessive voltage / current to the reverse conversion unit ( It is applied to the IGBT and the motor of the inverter unit.

  As a result, the IGBT of the reverse conversion unit is damaged, and the permanent magnet is demagnetized in the case of a motive motor in which the motor uses a permanent magnet. Normally, when the motor control device (inverter) is in operation, it is equipped with a function that shuts down the output when the current is excessive and protects the control device and the motor, but this protection function also uses the output signal of the current detector. When the output signal line of the current detector is not connected, the protection function does not operate.

  In the present invention, in view of the above-described conventional problems, when there is a connection error of the signal line (connection line) of the current detector, by detecting the erroneous connection and its type before the operation of the initial device, Provided are a motor control device and a compressor that prevent the motor control device from being damaged or demagnetized.

In order to solve the disadvantages of the prior art, the present invention provides a power converter for energizing a three-phase motor by changing the power source to a variable frequency three-phase alternating current, and a current detector for detecting a plurality of phases of energization current of the motor. A DC command for supplying a control signal to the power converter based on an external command signal and a detection signal of the current detector and for energizing a DC command current for motor positioning from the power converter in the initial stage of starting In a motor control device provided with a control unit for supplying
The control unit includes a determination unit that determines normality / abnormality of the connection of the current detector based on a detection signal pattern of the current detector when the positioning direct current is energized. A shut-off signal for shutting off the power supply to the converter is generated.

  In the motor control device described above, the determination unit determines that the current detector is abnormally connected when a predetermined level or less is detected as a detection signal of the current detector for a predetermined number of times when the positioning DC current is supplied. And generating a cut-off signal.

  In the motor control device described above, the determination unit determines that the current detector is a disconnection error.

  In the motor control device described above, the determination unit compares the detection signal of the current detector and the sign of the DC command current when the positioning DC is energized, and determines that the connection is abnormal if there is a mismatch. A shut-off signal is generated.

  In the motor control device described above, the determination unit compares the detection signal of the current detector and the sign of the DC command current for the same phase when the positioning DC current is supplied.

  In the motor control device described above, the determination unit determines that the current detector is reversely connected.

  In the motor control device described above, the control unit commands a coordinate converter that performs coordinate conversion of the detection signal of the current detector, and a DC command current for positioning after activation on the d-axis (or q-axis). A current controller configured to compare the sign of the detected value of the d-axis (or q-axis) obtained by coordinate conversion of the detection signal with the DC command current of the current controller. To do.

  Further, the present invention provides a compressor including a compressor main body that compresses a fluid, a motor that drives the compressor main body, and a control device that controls the motor, wherein the control device is the motor described in any one of the above. It is a control device.

  In the present invention, since it is necessary to prevent the motor control device from being damaged, a direct current for positioning the rotor of the motor is energized at an appropriate timing that does not cause damage immediately after startup, and an energization current as detected is detected. Whether or not (the detection pattern of the energization current) is determined. When the current from the phase where the current detector is installed is 0 (zero), it is determined that the connection of the phase is not connected. Setting of the threshold value for determining 0 and the determination timing from starting are appropriately selected depending on the motor control device and the motor to be applied.

  Further, even when the current detector is erroneously connected, the connection state is identified from the detection pattern of the energized current. According to the present invention, in the motor control device described above, the current detectors are installed in the U phase and the W phase, and the control unit performs coordinate conversion of the detection signal of the current detector, and positioning of the motor. A current controller that performs the DC command on the d-axis (or q-axis), and the determination unit detects the detected value on the d-axis (or q-axis) obtained by coordinate conversion of the detection signal and the DC command of the current controller. The connection state is determined to be normal when the detection pattern has the same sign, and the reverse connection is determined when the detection pattern has the reverse sign.

  Furthermore, when the motor is subjected to direct current energization, current disturbance may occur due to the movement of the rotor of the motor, and the energization current may temporarily be near zero. If the connection determination of the current detector is performed at this timing, an erroneous determination that it is not connected (disconnected) occurs. Therefore, by making determinations at appropriate plural timings, erroneous determination is prevented even when the detected current is disturbed.

  According to the present invention, in the motor control device and the compressor, the current detector connection status and the abnormal connection type determination are performed before the driving operation using the direct current energization of the motor positioning at the initial start-up. It is possible to prevent damage to the motor due to damage to the device, demagnetization, etc., and measures such as connection change after determination become easy. In addition, since incorrect connection determination is performed in parallel with the positioning operation of the motor, no new determination time is required.

It is a block block diagram of one Example of this invention. It is an operation | movement flowchart similarly. It is a wave form chart of command current of each phase similarly. Similarly, it is a wave form diagram of a detection current at the time of normal time and abnormality with respect to a command current of each phase. It is a wave form diagram of detection current of U phase and W phase at the time of reverse connection similarly. It is a wave form chart of d axis detection current at the time of normal time and abnormal time to a d axis command current waveform of other examples of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a block configuration of an embodiment of the present invention.

  1 is a motor control device (inverter device) that receives AC from the commercial power source 3 and converts it into three-phase AC of variable frequency and supplies it to a three-phase motor (or synchronous motor) 2. It is a power converter that converts to three-phase AC. The power converter 10 includes a forward conversion unit (rectification unit) 20, a smoothing unit 21, and an inverse conversion unit 22, and U, V, and W phase output lines are connected to the corresponding fixed pole windings of the motor 2. . Current detectors 30 and 31 for detecting energization current are provided on the U-phase and W-phase output lines, respectively. Reference numeral 4 denotes a command device that generates a command signal S including a start command for the motor 2 and a speed command for normal operation, and is provided outside the motor control device 1.

  15 is a three-phase signal line from 5 to 7 (U to W phase) to the power converter 10 based on the difference between the speed command signal of the command device 4 and the detection signals of the current detectors 30 and 31. A control unit that supplies phase control signals, and is composed of a microprocessor. In the control unit 15, the coordinate converter 11 that converts the U-phase and W-phase detection signals of the current detectors 30 and 31 into the d-axis and q-axis detection signals, the coordinate-converted detection signal and the command unit 4. A current controller 12 for generating a control current based on the speed command signal, and a vector controller 13 for generating a control voltage and a three-phase control signal from the control current, and further including the current detectors 30, 31 and coordinates. A determination unit 14 that receives signals from the converter 11, the current controller 12, and the vector controller 13 is provided.

  The determiner 14 determines normality / abnormality of the connection of the current detectors 30 and 31 from the detection signal pattern of the current detector, outputs a cut-off signal when determined to be abnormal, and supplies it to the power converter 10, Stop energization of three-phase AC from the output line.

  The current controller 12 sends a DC command current for motor positioning (rotor positioning) from the output line of the power converter 10 for a predetermined time to start the motor based on the start command of the command unit 4. In order to energize the two fixed pole windings, a DC command is applied to the signal lines 5 to 7 as a control signal. The DC command at this time is a voltage with a positive sign for the U phase (signal line 5), a voltage with a negative sign for the V and W phases (signal lines 6 and 7), and half the voltage for the U phase. The command current is energized from the output line at the same rate. The rotor (not shown) of the three-phase motor 2 has a permanent magnet, and is rotated to a fixed pole suitable for starting by direct current conduction to the fixed pole winding (the rotor is rotated and positioned). ) And prepare for subsequent activation.

  Reference numeral 16 denotes a compressor main body driven by the three-phase motor 2 and constitutes a compressor together with the motor control device 1 and the motor 2.

  The operation of the apparatus having the above configuration will be described with reference to flowcharts and waveform diagrams.

  When a start command signal is issued from the command device 4 in step 1 (S1) of FIG. 2, a constant voltage of a DC command is applied from the signal lines 5 to 7 of the control unit 15 for positioning the motor, and in response to this. A predetermined DC voltage is output from the three-phase output line of the power converter 10 (FIG. 2, S2). With this DC command, the energization current of each phase output line becomes a waveform that gradually increases as the command current as shown in FIG. That is, the U-phase command current increases with a positive sign, and the V and W-phase command currents increase with a negative sign and half the current of the U-phase. Reference numeral 50 denotes a timing for determination by the determiner 14 after the DC command is generated.

  When the current detectors 30 and 31 are arranged in the U-phase and W-phase of the output lines, respectively, and the connection lines 30a and 31a are normally connected to the control unit 15, the detection signals of the current detectors are also shown in FIG. The waveforms have the same tendency as the U-phase and W-phase currents shown in FIG. That is, in terms of the actual current values in FIG. 4, the detected currents (detection signals) having the same tendency as shown in (2) with respect to the actual command currents in each phase of (1) (W phase) (Part of current disturbance will be described later).

  However, when the connection lines 30a and 31a are not connected to the control unit 15 or disconnected, the detection signal of the corresponding current detector is zero or an extremely low level detection signal. For example, when the W-phase connection line 31a is disconnected, the W-phase detection signal is zero as shown in FIG. In this case, the determination unit 14 determines Yes in S3 of FIG. 2, generates the output cut-off signal H in S8, and the motor 2 is stopped. Next, in S9, the fact is displayed as a current detector disconnection error (display) (Not shown).

  Here, the rotor is rotated by direct current energization for positioning of the motor, but this rotation may generate a counter electromotive force in the coil of the fixed pole, which may disturb the detection current of the current detector. That is, as shown in FIG. 4B, for example, the W-phase detection signal is disturbed by the direct current energization for positioning, and is 0 (or a level close to 0) at the timing of 102. If the determination timing 50 in FIG. 4 (2) coincides with 102, the detection signal is 0, so that it is erroneously determined as a disconnection error of the current detector.

  Therefore, for example, when a plurality of determinations are performed at the timings 100, 101, 102, and 103 in FIG. 4 (2) and the detection signal is 0 at all timings, if the determination unit 14 determines a disconnection error, an erroneous determination is made. Can be prevented. Therefore, in S3 of FIG. 2, it is determined that there is a connection abnormality when a predetermined level or less is detected a predetermined number of times as a detection signal. This predetermined number of times is appropriately selected according to the type and capacity of the applied motor.

  If the detection signal of the current detector is not 0 and it is determined No in S3 of FIG. 2, it is determined in S4 whether the pattern of the detection signal of each phase is normal. That is, when the connection lines 30a and 31a are normally connected, the sign of the DC command current of each phase in FIG. 4 (1) and the sign of the detection signal of the corresponding phase in (2) match. The determination is Yes. In S5, the current detector is normally connected, and a control signal is output from the controller 15. In S6, the motor starts synchronous operation, and in S7, sensorless operation is performed. Note that the determiner 14 converts the DC command current of each phase output line of the power converter from the DC command of the signal lines 5 to 7 and makes it a determination target.

  Assuming that the connection lines 31a and 31a of the current detectors 30 and 31 are connected in reverse, for the U-phase and W-phase command currents in FIG. The W-phase detection signal (detection signal) has a negative sign and the W-phase detection signal has a positive sign as shown in FIG. Accordingly, the signs of the command current and the detection signal do not match for the U phase and the W phase, it is determined No in S4 of FIG. 2, the cutoff signal H is generated in S10, and the motor 2 is stopped. Next, in S11, a message indicating that the current detector is erroneously connected (reverse connection) error is displayed (the display is not shown).

  Thus, by comparing the sign of the detection signal and the command current for the same phase, it can be determined whether the connection state of the current detector is normal connection or incorrect (reverse) connection.

  1 includes a coordinate converter 11 that converts the U-phase and W-phase detection signals of the current detectors 30 and 31 into d-axis and q-axis, and a coordinate-converted detection signal and command unit. Since the current controller 12 that generates the control current based on the speed command signal 4 is provided, the connection state of the current detector can be determined using the d-axis and the q-axis.

  For example, when a DC command current is commanded on the d-axis, if the d-axis detection signal and the d-axis DC command current increase with the same sign, the connection state is normal and increases with a reverse sign (sign mismatch) If so, it can be determined that the connection is reverse.

  The determiner 14 takes a d-axis detection signal from the output of the coordinate converter 11 and takes a d-axis DC command current from the current controller 12. As shown in FIG. 6, the positive sign d-axis command current of (1) is detected as a positive sign d-axis detection current shown in (2) in normal connection, and (3) in abnormal (reverse) connection. As shown, it is detected as a negative sign d-axis detection current (d-axis detection signal). In S4 of FIG. 2, the sign of the detection signal and the DC command current is compared for the d-axis. If they match, it is determined Yes, and the mismatch is determined No. Subsequent steps are the same as described above.

  The above describes the case where a DC command current is commanded on the d-axis, but when commanding on the q-axis, the connection status of the current detector can be determined for the q-axis. Similarly to the case of the d-axis, the sign of the q-axis detection signal and the q-axis DC command current are compared by the determiner 14, and the connection status is determined based on the match or mismatch.

  If the motor control device 1 having the above configuration is mounted on a compressor, the above operation can prevent the motor control device from being damaged, the motor from being damaged due to demagnetization, or the like, and the entire compressor can be prevented from being damaged. Also, if the compressor is found to be misconnected after operation, the countermeasure processing is troublesome by adjusting the pressure with other connected devices, etc., but in parallel with the motor positioning operation before starting the compressor operation, Since the connection status of the detector and the type of abnormal connection are determined, measures such as connection change of the connection line are facilitated. In addition, since erroneous connection determination is performed during the positioning operation of the motor, a new determination time is not required.

  DESCRIPTION OF SYMBOLS 1 ... Motor control device, 2 ... 3-phase motor, 3 ... Power supply, 4 ... Commander, 5-7 ... 3-phase control signal, 10 ... Power converter, 11 ... Coordinate converter, 12 ... current controller, 14 ... determiner, 15 ... controller, 16 ... compressor body, 13 ... vector controller, 20 ... forward converter, 21 ... smooth , 22 ... Inverse conversion unit, 30 ... Current detector (U phase), 30a ... Detection current (U phase), 31 ... Current detector (W phase), 31a ... Detection current (W phase) ), 50... Judgment timing at the time of DC energization, 100, 101, 102, 103.

Claims (8)

A power converter that supplies power to the three-phase motor by changing the power source to variable-frequency three-phase AC, a current detector that detects a plurality of phases of the motor current, an external command signal, and a detection signal of the current detector And a control unit for supplying a DC command for supplying a DC command current for motor positioning from the power converter in the initial stage of startup,
The control unit includes a determination unit that determines normality / abnormality of the connection of the current detector based on a detection signal pattern of the current detector when the positioning direct current is energized. A motor control device for generating a shut-off signal for shutting off the energization of the converter.   The motor control device according to claim 1, wherein the determination unit determines that the current detector is abnormally connected when a predetermined level or less is detected as a detection signal of the current detector for a predetermined number of times when the positioning direct current is energized. A motor control device that generates a shut-off signal.   3. The motor control device according to claim 2, wherein the determination unit determines that the current detector is disconnected.   The motor control device according to claim 1, wherein the determination unit compares the detection signal of the current detector with the sign of the DC command current when the positioning DC current is supplied, and determines that the connection is abnormal if the two do not match. A motor control device that generates a shut-off signal.   5. The motor control device according to claim 4, wherein the determination device compares the detection signal of the current detector and the sign of the DC command current for the same phase when the positioning DC current is supplied.   6. The motor control apparatus according to claim 4, wherein the determination unit determines that the current detector is reversely connected.   5. The motor control device according to claim 4, wherein the control unit commands a coordinate converter that performs coordinate conversion of the detection signal of the current detector and a DC command current for motor positioning on the d-axis (or q-axis). A motor control device comprising: a current controller, wherein the determination unit compares the sign of a coordinate-converted d-axis (or q-axis) detection signal and a DC command current of the current controller.   A compressor comprising: a compressor main body that compresses fluid; a motor that drives the compressor main body; and a control device that controls the motor. The control device according to any one of claims 1 to 7. A compressor characterized by being a motor control device.

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