JP5052854B2 - Motor control system, phase loss detection device, and phase loss detection method - Google Patents

Description

  The present invention relates to a motor control system, a phase loss detection device, and a phase loss detection method for a multiphase AC motor such as a three-phase AC motor.

Various techniques for detecting the open phase of a multiphase AC motor have been proposed. In Patent Document 1, the current of each phase supplied to the three-phase AC motor is detected, the change rate of the d-axis current is calculated from the detected value, and an open phase detection signal is output when the change rate exceeds a threshold value Techniques to do this are disclosed.
JP 2003-348898 A

  The technique of the cited document 1 requires a circuit for obtaining a change rate such as a differential circuit, and the configuration is complicated. In general, the differentiation circuit cannot expect a stable operation and easily amplifies the disturbance. Therefore, there is a possibility that the phase loss is erroneously detected due to the disturbance.

  An object of the present invention is to provide a motor control system, a phase loss detection device, and a phase loss detection method capable of reliably detecting phase loss with a simple configuration.

  A motor control system according to the present invention includes a multiphase AC motor, a power supply unit that supplies multiphase AC power to the motor, and a current detection that detects a current of each phase supplied from the power supply unit to the motor. A phase detection unit that detects a rotation phase of the motor, and a current of each phase detected by the current detection unit is dq converted based on the phase detected by the phase detection unit, and d-axis current and q-axis A dq converter that calculates current, an absolute value of the d-axis current calculated by the dq converter exceeds a predetermined d-axis threshold, and an absolute value of the d-axis current calculated by the dq converter and the dq conversion A phase loss detection unit that outputs a phase loss detection signal when a predetermined determination condition including that the ratio of the absolute value of the q-axis current calculated by the unit is within a predetermined range is satisfied .

  Preferably, the ratio is a value obtained by dividing the absolute value of the d-axis current calculated by the dq converter by the absolute value of the q-axis current calculated by the dq converter, and the determination condition includes: It is further included that the absolute value of the q-axis current calculated by the dq converter exceeds a predetermined q-axis threshold value.

  Preferably, a deviation calculation unit for calculating a deviation between a target value of the d-axis current and the q-axis current and a d-axis current and a q-axis current calculated by the dq conversion unit, and a deviation calculated by the deviation calculation unit A target voltage calculation unit that calculates a target value of the d-axis voltage and the q-axis voltage based on the above, and a phase value detected by the phase detection unit based on the target value of the d-axis voltage and the q-axis voltage calculated by the target voltage calculation unit. And a reverse conversion unit that performs reverse conversion on the basis of dq and calculates a target value of the voltage of each phase, and the power supply unit is a voltage of the target value of the voltage of each phase calculated by the reverse conversion unit Is applied to the motor.

  The phase loss detection device of the present invention includes a current detection unit that detects a current of each phase supplied to a multiphase AC motor, a phase detection unit that detects a rotation phase of the motor, and each of the current detection units detected The phase current is subjected to dq conversion based on the phase detected by the phase detection unit to calculate the d-axis current and the q-axis current, and the absolute value of the d-axis current calculated by the dq conversion unit is predetermined. On the condition that the ratio of the absolute value of the d-axis current calculated by the dq converter and the absolute value of the q-axis current calculated by the dq converter is within a predetermined range. A phase loss detection unit that outputs a phase loss detection signal when a predetermined determination condition is satisfied.

  According to the phase loss detection method of the present invention, the ratio between the absolute value of the d-axis current and the absolute value of the q-axis current calculated by dq conversion of the detected value of each phase current supplied to the multiphase AC motor is predetermined. The phase loss is detected when a predetermined determination condition including the condition of being within the range is satisfied.

  According to the present invention, an open phase can be reliably detected with a simple configuration.

  FIG. 1 is a block diagram showing a transport carriage 1 to which a motor control system according to an embodiment of the present invention is applied. The transport cart 1 is for transporting an object to be transported such as a mold or a workpiece in a factory, for example.

  The transport carriage 1 includes a base body 2 and a plurality of driving wheels 3F and 3R that support the base body 2 (hereinafter, simply referred to as “driving wheels 3” and may not be distinguished from each other) and driving wheels 3F and 3R. Motors 5F and 5R (hereinafter simply referred to as “motor 5”, both of which may not be distinguished from each other), a drive unit 7 for supplying power to the motor 5, and a phase failure of the motor 5 are detected. A phase loss detection unit 9 and a control unit 11 that controls the operation of the drive unit 7 are provided.

  The base 2 and the drive wheel 3 are appropriately designed according to the purpose of use of the transport carriage 1. For example, the base body 2 is configured in an appropriate shape such as a chassis shape or a box shape from an appropriate material such as metal, resin, or wood. The drive wheel 3 is formed of an appropriate material such as metal, resin, rubber or the like. The drive wheel 3 may roll on a track, or may roll on an arbitrary place. The number and type of drive wheels 3 are also set as appropriate according to the purpose of use of the transport carriage 1. In FIG. 1, a pair of driving wheels 3F (the driving wheel 3F at the back of the page is not shown) is provided as a front wheel, and a pair of driving wheels 3R (the driving wheel 3R at the back of the page is not shown) is provided as a rear wheel. The case where the drive wheel 3 of this is provided is illustrated. Moreover, the case where the driving wheel 3F and the driving wheel 3R have the same diameter is illustrated.

  The motor 5F drives a pair of drive wheels 3F, and the motor 5R drives a pair of drive wheels 3R. One motor (a total of four motors) may be provided corresponding to each drive wheel 3. An appropriate gear train such as a speed increasing gear, a speed reducing gear, a differential gear, or the like is provided between the motor 5 and the drive wheel 3 in accordance with the purpose of use of the transport carriage 1, but description thereof is omitted. The motor 5F and the motor 5R are composed of, for example, the same type of motor.

  The motor 5 is a three-phase AC motor driven by three-phase AC power. The motor 5 may be an induction motor or a synchronous motor. Although not specifically shown, the motor 5 includes a stator and a rotor that can rotate with respect to the stator. One of the stator and the rotor is a field, and the other is an armature. The motor 5 may be a multiphase AC motor other than the three-phase motor.

  The motor 5 is configured as a servo motor. The motor 5F is provided with an encoder 13 that detects the rotation of the motor 5F and outputs a rotation detection signal Sp corresponding to the detection result. The encoder 13 may be configured by a known appropriate encoder such as a magnetic encoder or an optical encoder. As described above, the drive wheels 3F and 3R are configured to have the same diameter, and basically rotate at the same rotational speed. Therefore, the encoder 13 detects representative values of rotations of a plurality of motors. Will do.

  The encoder 13 outputs a pulse signal as the rotation detection signal Sp every time the rotor of the motor 5F rotates by a predetermined angle. That is, the rotation detection signal Sp is composed of a number of pulse trains corresponding to the number of rotations of the motor 5F. Therefore, the rotational speed of the motor 5 is specified by counting the number of pulses per unit time. In other words, the encoder 13 functions as a speed detection unit that detects the rotational speed of the motor 5F.

  The encoder 13 outputs a rotation detection signal Sp that can specify the rotation phase θ (rotation position) of the motor 5F. For example, the pulse train output while the motor 5F makes one rotation includes one pulse signal having a different length from the other pulse trains, and the detection of the pulse signal having a different length results in the detection of the motor 5F. The origin of the rotational phase θ is specified. Then, the rotational phase θ from the origin of the motor 5F is specified by the number of pulses after the origin is detected. Therefore, the encoder 13 functions as a phase detector that detects the rotational phase θ of the motor 5F.

The drive unit 7 supplies the motor 5 with electric power having a magnitude corresponding to the input torque command signal St. The power supplied by the drive unit 7 is three-phase AC power. The currents Iu, Iv, and Iw of each phase of the power are, for example, the amplitude is I ₀ ,
Iu = I ₀ sin θ
Iv = I ₀ sin (θ + 2 / 3π) (1)
Iw = I ₀ sin (θ−2 / 3π)
It is represented by The drive unit 7 supplies equivalent power to the motor 5F and the motor 5R. The drive unit 7 performs feedback control of the motor 5 based on the rotation detection signal Sp from the encoder 13. The drive unit 7 detects the currents Iu, Iv, and Iw of each phase, and outputs a current detection signal Si to the phase loss detection unit 9 based on the detected values.

  The phase loss detection unit 9 determines whether or not phase loss has occurred based on the current detection signal Si output from the drive unit 7. If it is determined that phase loss has occurred, the phase loss detection unit 9 controls the phase loss detection signal Sf. To the unit 11.

  The control part 11 is comprised by the computer containing CPU, RAM, ROM, an external storage device, etc., for example. The control unit 11 generates the same torque command signal St for the plurality of motors 5 and outputs the same torque command signal St to the drive unit 7 to perform parallel operation of the plurality of motors 5. In other words, the control unit 11 does not control the plurality of motors 5 independently.

  Specifically, the control unit 11 performs speed feedback control of the motor 5 based on the rotation detection signal Sp from the encoder 13. That is, the number of pulses included in the rotation detection signal Sp is counted every unit time to identify the speed of the motor 5, and the torque command signal St is generated so that the speed of the motor 5 becomes a predetermined target speed. Output to. The target speed of the motor 5 is appropriately set by, for example, performing a predetermined operation on an operation unit (not shown) or preliminarily stored in a recording device (not shown) according to the position of the transport carriage 1. It is set by reading out.

  In addition, when the phase loss detection signal Sf is input from the phase loss detection unit 9, the control unit 11 performs a predetermined abnormality process. The abnormality process is, for example, a process for stopping the operation of the transport carriage 1. Specifically, for example, when the phase loss detection signal Sf is input, the control unit 11 generates and outputs a torque command signal St that sets the torque of the motor 5 to 0 regardless of the target speed. To do. Moreover, the process at the time of abnormality is a process which alert | reports abnormality to an operator, for example. Specifically, for example, when the phase loss detection signal Sf is input, the control unit 11 outputs a predetermined notification sound from a speaker (not shown) or turns on, blinks, or turns off a light emitting element (not shown). Or a predetermined image or message is displayed on a display device (not shown).

  FIG. 2 is a block diagram illustrating details of the drive unit 7.

  The drive part 7 is comprised by the electric circuit containing IC, an inverter, etc., for example. The torque command signal St input from the control unit 11 to the drive unit 7 is converted into currents Iu, Iv, and Iw of each phase via the target voltage calculation unit 21, the inverse conversion unit 23, and the power supply unit 25, and is transmitted to the motor 5. Is output. Further, the currents Iu, Iv, and Iw of each phase are detected by current detection units 27u, 27v, and 27w (hereinafter simply referred to as “current detection unit 27” and may not be distinguished from each other), and the detected values thereof. Is input to the target voltage calculation unit 21 through the dq conversion unit 29 and the subtractors 31d and 31q (hereinafter simply referred to as “subtractor 31”, which may not be distinguished from each other) and is used for feedback control. The Specifically, it is as follows.

  A torque command signal St is input to the target voltage calculation unit 21. The torque command signal St includes, for example, information on a target d-axis current Id_T that is a target value of the d-axis current and a target q-axis current Id_T that is a target value of the q-axis current. The d-axis is an axis extending in the direction of the magnetic flux generated by the field in the motor 5, and the q-axis is an axis extending in a direction orthogonal to the d-axis. The d-axis current is a reactive current, and the q-axis current is proportional to the torque of the motor 5. Therefore, the target d-axis current Id_T is normally set to 0, and the target q-axis current Iq_T is set to be proportional to the target torque of one motor 5.

  Based on the target d-axis current Id_T and the target q-axis current Iq_T, the target voltage calculator 21 is a voltage necessary for supplying the target d-axis current Id_T and the target q-axis current Iq_T to each motor 5, that is, d. A target d-axis voltage Vd_T that is a target value of the axis voltage and a target q-axis voltage Vq_T that is a target value of the q-axis voltage are calculated, and a signal corresponding to the calculated value is output to the inverse conversion unit 23. The calculation is performed using a feedback gain as will be described later.

  In general, the following equation (2) is established between the target d-axis current Id_T and the target q-axis current Id_T, and the target d-axis voltage Vd_T and the target q-axis voltage Vd_T.

Here, R is the resistance of the armature, L is the inductance of the armature, ω is the angular velocity (electrical angular velocity) of the rotor, P is the differential operator (d / dt), and Eq is the velocity electromotive force.

  The inverse conversion unit 23 performs inverse dq conversion on the target d-axis voltage Vd_T and the target q-axis voltage Vq_T calculated by the target voltage calculation unit 21 based on the rotational phase θ of the motor 5, and the target voltages Vu_T and Vv_T for each phase. , Vv_T is calculated, and a signal corresponding to the calculated value is output to the power supply unit 25. The dq inverse transformation is expressed by the following equation (3).

  The rotation phase θ is calculated based on the rotation detection signal Sp from the encoder 13 as described above. The calculation is performed by the inverse conversion unit 23 or a rotation phase calculation unit (not shown) provided between the encoder 13 and the inverse conversion unit 23.

  The power supply unit 25 includes, for example, an inverter, converts DC power from a power source (not shown) into AC power, and uses the target voltages Vu_T, Vv_T, and Vv_T calculated by the inverse conversion unit 23 for the motor 5 Apply to. The power supply unit 25 and the motor 5 are connected by a cable, for example. The motor 5F and the motor 5R are connected in parallel to the power supply unit 25, and the same voltage is applied to the motor 5F and the motor 5R.

  The current detection units 27u, 27v, and 27w detect the currents Iu, Iv, and Iw of the respective phases, and output signals corresponding to the detected values to the dq conversion unit 29. For example, the current detection unit 27 can detect the currents Iu, Iv, and Iw of each phase supplied to the motor 5F, and the connection point between the motor 5F and the motor 5R among the power supply unit 25 to the motor 5F. Rather than the motor 5F. Since the motor 5F and the motor 5R are composed of the same type of motor and are connected in parallel, the current supplied to the motor 5R is equal to the current supplied to the motor 5F. Therefore, the current detection unit 27 detects a representative value of the current supplied to the plurality of motors 5.

  The dq conversion unit 29 performs dq conversion on the currents Iu, Iv, and Iw detected by the current detection units 27u, 27v, and 27w based on the rotation phase θ, and calculates a d-axis current Iq and a q-axis current Iq. The dq conversion is expressed by the following equation (4).

The rotation phase θ is calculated based on the rotation detection signal Sp from the encoder 13 as described above. The calculation is performed by the dq conversion unit 29 or a rotation phase calculation unit (not shown) provided between the encoder 13 and the dq conversion unit 29.

  Then, the dq converter 29 outputs a signal including information on the calculated d-axis current Iq and q-axis current Iq. The signal is input to the subtractor 31 and is input to the phase loss detection unit 9 as the current detection signal Si described with reference to FIG.

  The subtractor 31d subtracts the d-axis current Id calculated by the dq converter 29 from the target d-axis current Id_T and outputs the result to the target voltage calculator 21. The subtractor 31q subtracts the q-axis current Iq calculated by the dq converter 29 from the target q-axis current Iq_T and outputs the result to the target voltage calculator 21.

  The target voltage calculation unit 21 calculates the target d-axis voltage Vd_T and the target q-axis voltage Vq_T based on the deviation calculated by the subtractors 31d and 31q. For example, the target voltage calculation unit 21 calculates the target d-axis voltage Vd_T and the target q-axis voltage Vq_T by the following equation (5) so that PI control is performed.

Kp is a proportional gain, _{K I} is an integral gain. Proportional gain Kp and the integral gain K _I is the above (2), the number of motor 5, are appropriately set based on experiments or the like.

  FIG. 3 is a block diagram illustrating a configuration of the phase loss detection unit 9.

  As described above, the phase loss detection unit 9 is configured as a circuit that receives the current detection signal Si from the drive unit 7 and outputs the phase loss detection signal Sf when the phase loss detection is detected. Specifically, it is as follows. In the following description, a signal including 1-bit information output from a logic circuit or the like may be described as a signal having a value of 0 (false) or 1 (true).

  The absolute value circuit 41d receives a signal including information on the d-axis current Id from the current detection signal Si, calculates the absolute value of the d-axis current Id, and outputs a signal corresponding to the calculated value. Similarly, the absolute value circuit 41q receives a signal including information on the q-axis current Iq from the current detection signal Si, calculates the absolute value of the q-axis current Iq, and outputs a signal corresponding to the calculated value.

  The comparator 43d receives a signal from the absolute value circuit 41d and a signal including information on a predetermined threshold Th. The threshold Th is input from the control unit 11 to the comparator 43d, for example. The comparator 43d compares the absolute value of the d-axis current Id with a threshold value Th, and outputs a signal having a value of 1 when the absolute value of the d-axis current Id is larger than the threshold value Th. Outputs a 0 signal.

  Similarly, the comparator 43q receives a signal from the absolute value circuit 41q and a signal including information on a predetermined threshold Th. The threshold value Th is input from the control unit 11 to the comparator 43q, for example. The comparator 43q compares the absolute value of the q-axis current Iq with the threshold value Th, and outputs a signal having a value of 1 when the absolute value of the q-axis current Iq is larger than the threshold value Th. Outputs a 0 signal.

  The AND circuit 45 receives the signal from the comparator 43d and the signal from the comparator 43q, and outputs a signal representing the logical product of both signals. That is, when a signal having a value of 1 is input from both the comparator 43d and the comparator 43q, in other words, when both the d-axis current Id and the q-axis current Iq exceed the threshold Th, the value is 1. A signal is output. Otherwise, a signal having a value of 0 is output.

  The ratio calculator 47 receives the signal from the comparator 43d and the signal from the comparator 43q, calculates the ratio between the absolute value of the d-axis current Id and the absolute value of the q-axis current Iq, and calculates the calculated value. A corresponding signal is output. For example, the ratio calculator 47 calculates, as a ratio, a value | Id | / | Iq | obtained by dividing the absolute value of the d-axis current Id by the absolute value of the q-axis current Iq.

  The comparator 49U receives the signal from the ratio calculator 47 and a signal including information on a predetermined upper limit value Li_U. The upper limit value Li_U is input from the control unit 11 to the comparator 49U, for example. The comparator 49U compares the ratio | Id | / | Iq | with the upper limit value Li_U. When the ratio | Id | / | Iq | is larger than the upper limit value Li_U, the comparator 49U outputs a signal having a value of 1; In the case of, a signal having a value of 0 is output.

  Similarly, the comparator 49D receives the signal from the ratio calculator 47 and the signal including information on the predetermined lower limit value Li_D. The lower limit value Li_D is input from the control unit 11 to the comparator 49D, for example. The comparator 49D compares the ratio | Id | / | Iq | with the lower limit value Li_D. When the ratio | Id | / | Iq | is larger than the lower limit value Li_D, the comparator 49D outputs a signal having a value of 1; In the case of, a signal having a value of 0 is output.

  The AND circuit 51 is a two-input AND circuit in which one input is inverted. The AND circuit 51 receives the inverted signal from the comparator 49U and also receives the signal from the comparator 49D and outputs a signal representing the logical product of both signals. That is, the AND circuit 51 receives a signal having a value of 0 from the comparator 49U and a signal having a value of 1 from the comparator 49D, in other words, the ratio | Id | / | Iq | Is in the range from the lower limit Li_D to the upper limit Li_U, a signal having a value of 1 is output, and a signal having a value of 0 is output otherwise.

  The AND circuit 53 receives the signal from the AND circuit 45 and the signal from the AND circuit 51, and outputs a signal representing the logical product of both signals. That is, a signal having a value of 1 is output when a signal having a value of 1 is input from both the AND circuit 45 and the AND circuit 51, and a signal having a value of 0 is output otherwise.

  A signal having a value of 1 is output as a phase loss detection signal Sf that is output when phase loss is detected. That is, the control unit 11 or the like executes a predetermined abnormality process when a signal having a value of 1 is input from the AND circuit 53.

  As described above, in the phase loss detection unit 9, both the absolute value of the d-axis current Id and the absolute value of the q-axis current Iq exceed the threshold Th, and the absolute value of the d-axis current Id and the absolute value of the q-axis current Iq. When the value ratio | Id | / | Iq | is in the range from the lower limit value Li_D to the upper limit value Li_U, the phase loss detection signal Sf is output.

  The phase loss detection process may be performed at an appropriate cycle. That is, the input of the current detection signal Si to the phase loss detection unit 9 and / or the drive of the phase loss detection unit 9 may be performed at an appropriate cycle. For example, it may be performed in synchronization with a predetermined clock signal, or may be performed with a period longer than the period of the clock signal.

  FIG. 4 is a diagram for explaining the operation and effects of the transport carriage 1. FIG. 4A shows the time-dependent changes in the d-axis current Id and the q-axis current Iq when an open phase occurs. ) Shows the time-dependent changes in the absolute value | Id | of the d-axis current, the absolute value | Iq | of the q-axis current, the ratio | Id | / | Iq | Show.

  In the state where no phase failure occurs in the transport carriage 1, the d-axis current Id is maintained at 0 and the q-axis current Iq is maintained at a value proportional to the target torque by feedback control. When the target torque is constant, the q-axis current Iq is also kept constant at a value proportional to the target torque. When a phase failure occurs, the d-axis current Id and the q-axis current Iq change into a wave shape as shown in FIG.

This variation can also be understood from the above formula. That is, when an open phase occurs, the power supplied from the power supply unit 25 to the motor 5 becomes a single-phase alternating current, and the current of each phase is
Iu = I ₀ sin θ
Iv = −Iu (6)
It is represented by When the equation (6) is substituted into the equation (4), the d-axis current Id and the q-axis current Iq calculated by the dq converter 29 are represented by a periodic function having the rotation phase θ as a variable. Specifically, the calculation of the d-axis current Id is multiplied by the cosine function, and the calculation of the q-axis current Iq is multiplied by the sin function. Therefore, the phase of the d-axis current Id and the q-axis current Iq is approximately 1 / It becomes a periodic function shifted by 4 cycles.

However, actually the waveform of the d-axis current Id and q-axis current Iq calculated by dq conversion section 29, depending on the setting of such proportional gain Kp and the integral gain K _I. For example, as shown in FIG. 4A, the d-axis current Id has a distorted waveform with an average value of approximately 0, and the d-axis current Id has an average value of approximately the target q-axis current Iq and 0 to the target. It becomes a distorted waveform that fluctuates between about twice the q-axis current Iq.

  Since the d-axis current Id should originally be zero, the phase loss can be detected by detecting that the absolute value | Id | of the d-axis current exceeds the threshold Th by the comparator 43d. The threshold value Th is set to an appropriate size so as to prevent erroneous detection of a missing phase due to minute fluctuations in the d-axis current Id caused by feedback control or minute fluctuations caused by disturbance when no missing phases occur.

  Since the ratio | Id | / | Iq | of the absolute value of the d-axis current Id and the absolute value of the q-axis current Iq should be essentially 0 similarly to the d-axis current Id, the comparator 49D By detecting that Id | / | Iq | exceeds the lower limit value Li_D, it is possible to detect an open phase. The lower limit value Li_D is set to an appropriate size so as to prevent erroneous detection of a missing phase due to minute fluctuations such as the d-axis current Id due to feedback control or minute fluctuations due to disturbance when no missing phases occur. The FIG. 4B illustrates a case where the lower limit value Li_D = the threshold value Th.

  As described above, the waveform of the d-axis current Id and the waveform of the q-axis current Iq when phase loss occurs are out of phase. Due to the phase shift, the fluctuation of the d-axis current Id and the fluctuation of the ratio | Id | / | Iq | are out of phase. Therefore, when the d-axis current exceeds the threshold Th and the ratio | Id | / | Iq | exceeds the lower limit value Li_D, the phase loss is detected when only one of the conditions is satisfied. The condition for detecting an open phase becomes stricter than when detecting an open phase.

  For example, when no phase loss occurs, when disturbance is instantaneously mixed into any one of the currents Iu, Iv, and Iw of each phase, the disturbance is expressed as d-axis as understood from the equation (4). The current is affected by the form multiplied by the sin function, and the q-axis current is affected by the form multiplied by the cos function. Therefore, even if a disturbance is mixed, both of the above two conditions are not always satisfied.

  On the other hand, since the phase loss is continuous, when the phase failure occurs, both the d-axis current Id and the ratio | Id | / | Iq | There is a phase that becomes a magnitude. Therefore, by setting both of the above two conditions to be satisfied, it is possible to prevent malfunction of phase loss detection due to disturbance.

  Since the ratio | Id | / | Iq | uses the absolute value | Iq | of the q-axis current as the denominator, when the absolute value | Iq | of the q-axis current becomes small, as shown in FIG. , The ratio | Id | / | Iq | becomes a large value, varies, and the influence of errors also increases. Therefore, by further adding the condition that the ratio | Id | / | Iq | does not exceed the upper limit value Li_U, the phase loss detection based on the ratio | Id | / | Iq | is reliably performed.

  Similarly, by further adding the condition that the absolute value | Iq | exceeds the threshold Th, the phase loss detection based on the ratio | Id | / | Iq | is reliably performed.

  FIG. 4B shows the operation and effect as described above. That is, both the absolute value of the d-axis current Id and the absolute value of the q-axis current Iq exceed the threshold Th, and the ratio of the absolute value of the d-axis current Id and the absolute value of the q-axis current Iq | Id | / | Iq The condition that | is in the range from the lower limit value Li_D to the upper limit value Li_U is intermittently satisfied during the rotation of the motor 5 (the phase loss detection signal Sf is intermittently output), and the phase loss detection of the motor 5 is detected. Surely done.

  As described above, according to the above embodiment, it is possible to detect an open phase with a relatively simple configuration without providing a differentiation circuit or the like, and to prevent malfunction due to disturbance.

  In addition, the d-axis current and the q-axis current are calculated from detecting the phase failure of the motor 5 in which feedback control is performed using the d-axis current and the q-axis current as control variables based on the d-axis current and the q-axis current. Therefore, it is not necessary to newly provide a circuit for doing so, and the configuration is simple.

  In the above embodiment, the combination of the drive unit 7 and the phase loss detection unit 9 is an example of the motor control system of the present invention, the motor 5 is an example of the multiphase AC motor of the present invention, and the encoder 13 is It is an example of the phase detector of the present invention, the threshold Th is an example of the d-axis threshold and the q-axis threshold of the present invention, the subtractor 31d and the subtractor 31q are an example of the deviation calculator of the present invention, and the current detector 27, the encoder 13, the dq converter 29, and the phase loss detection unit 9 are examples of the phase loss detection device of the present invention.

  The present invention is not limited to the above embodiment, and may be implemented in various aspects.

  The object to which the present invention is applied is not limited to the transport carriage. The present invention may be applied to any device that needs to detect a motor phase failure. Further, the motor control system to which the present invention is applied is not limited to the one that performs feedback control using the d-axis current and the q-axis current. For example, the present invention may be applied to a motor control system that controls a step motor.

  A single motor or a plurality of motors may be provided. When a plurality of motors are provided and operated in parallel by the control unit (11), the drive unit (7) and / or the phase loss detection unit (9) that drives the motor in accordance with a command from the control unit corresponds to the plurality of motors. A plurality may be provided, or one may be provided corresponding to a plurality of motors as in the embodiment. Further, a part of the drive unit and the phase loss detection unit may be provided corresponding to the plurality of motors, and the other part may be provided corresponding to the plurality of motors.

  For example, in the embodiment, the case where one drive unit 7 is provided for a plurality of motors has been illustrated, but two drive units 7 are provided corresponding to the two motors 5F and 5R, and one control unit 11 The same torque command signal St may be output to the two drive units 7, and the two drive units 7 may drive the motors 5F and 5R, respectively. In this case, the current detection unit 27 of each drive unit 7 detects the currents of the motors 5F and 5R, so that each drive unit 7 is independently based on the same torque command signal St. Feedback control of the motors 5F and 5R is performed.

  For example, in the embodiment, the case where one power supply unit 25 is provided for a plurality of motors in one drive unit 7 is illustrated, but the power supply unit 25 corresponds to the motors 5F and 5R in one drive unit 7. And the target voltages Vu_T, Vv_T, Vw_T of each phase are output from one inverse conversion unit 23 to the two power supply units 25, and the two power supply units 25 have the same target voltages Vu_T, Vv_T, Vw_T. Based on the above, voltages may be applied to the motors 5F and 5R, respectively.

  For example, in the embodiment, a case where one encoder 13 (phase detection unit) and one current detection unit 27u, 27v, and 27w are provided for each of a plurality of motors is illustrated, but the encoder 13 (phase detection unit) and current detection are provided. A plurality of units 27u, 27v, and 27w are provided for a plurality of motors, and the maximum value, the minimum value, or the average of the detection values of the plurality of encoders 13 is converted into one dq conversion unit, one inverse conversion unit, and one control unit. The maximum value, the minimum value, or the average of the detection values of the plurality of current detection units 27u, 27v, and 27w may be input to one dq conversion unit to contribute to feedback control and phase loss detection.

  For example, in the embodiment, the case where feedback control and phase loss detection are performed based on the d-axis current and q-axis current (torque) of one motor is exemplified. However, the d-axis current and q-axis current (torque) of a plurality of motors are exemplified. )), Feedback control or phase loss detection may be performed.

  The ratio between the absolute value of the d-axis current and the absolute value of the q-axis current is not limited to the ratio having the q-axis current as the denominator. For example, the phase loss can be detected when the ratio calculated by dividing the absolute value of the q-axis current by the absolute value of the d-axis current becomes smaller than a predetermined threshold. However, setting the threshold value and the like is easier when the d-axis current is a numerator.

  In the present invention, it is not an essential requirement that the absolute value of the q-axis current exceeds a predetermined q-axis threshold value. For example, in FIG. 3, the absolute value circuit 41q, the comparator 43q, and the AND circuit 45 may be omitted.

  The phase loss detection unit is a determination condition for determining whether or not phase loss has occurred, for example, the absolute value of the d-axis current exceeds a predetermined d-axis threshold, and the absolute value of the d-axis current and the q-axis current An appropriate configuration may be employed as long as it can be determined whether or not the condition that the ratio to the absolute value is within a predetermined range is satisfied.

  In the embodiment, the case where the threshold value of the d-axis current and the threshold value of the q-axis current are the same is illustrated, but these may be set separately. The upper limit value (Li_U) and lower limit value (Li_D) to be compared with the threshold value of the d-axis current, the threshold value of the q-axis current, and the ratio may be a constant or a value that changes according to a torque command or the like. There may be.

The block diagram which shows the structure of the conveyance trolley | bogie which concerns on embodiment of this invention. The block diagram explaining the drive part of the conveyance trolley | bogie of FIG. FIG. 2 is a block diagram for explaining a phase loss detection unit of the transport carriage in FIG. 1. The figure explaining the operation | movement and effect of the conveyance trolley | bogie of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Conveyance cart (apparatus which applied the motor control system), 5F, 5R ... Motor (polyphase alternating current motor), 7 ... Drive part, 13 ... Encoder (phase detection part), 9 ... Open phase detection part, 25 ... Electric power Supply unit, 27u, 27v, 27w ... current detection unit, 29 ... dq conversion unit.

Claims (5)

A polyphase AC motor,
A power supply unit for supplying multiphase AC power to the motor;
A current detection unit that detects a current of each phase supplied to the motor from the power supply unit;
A phase detector for detecting the rotational phase of the motor;
A dq conversion unit that dq-converts the current of each phase detected by the current detection unit based on the phase detected by the phase detection unit, and calculates a d-axis current and a q-axis current;
The absolute value of the d-axis current calculated by the dq converter exceeds a predetermined d-axis threshold, and at the same time , the absolute value of the d-axis current calculated by the dq converter and the q-axis current calculated by the dq converter A phase loss detection unit that outputs a phase loss detection signal when a predetermined determination condition including a condition that the ratio of the absolute value is within a predetermined range is satisfied,
A motor control system. The ratio is a value obtained by dividing the absolute value of the d-axis current calculated by the dq converter by the absolute value of the q-axis current calculated by the dq converter,
The determination condition includes that when the absolute value of the d-axis current calculated by the dq converter exceeds the d-axis threshold, and at the same time, when the ratio is within the predetermined range, The motor control system according to claim 1, further comprising that the absolute value of the q-axis current calculated by the dq converter exceeds a predetermined q-axis threshold value. a deviation calculator for calculating a deviation between the target values of the d-axis current and the q-axis current and the d-axis current and the q-axis current calculated by the dq converter,
A target voltage calculation unit that calculates a target value of the d-axis voltage and the q-axis voltage based on the deviation calculated by the deviation calculation unit;
An inverse conversion unit that performs dq inverse conversion on the target values of the d-axis voltage and the q-axis voltage calculated by the target voltage calculation unit based on the phase detected by the phase detection unit, and calculates a target value of the voltage of each phase; ,
Further comprising
The motor control system according to claim 1, wherein the power supply unit applies a voltage of a target value of the voltage of each phase calculated by the inverse conversion unit to the motor. A current detector for detecting the current of each phase supplied to the multiphase AC motor;
A phase detector for detecting the rotational phase of the motor;
A dq conversion unit that dq-converts the current of each phase detected by the current detection unit based on the phase detected by the phase detection unit, and calculates a d-axis current and a q-axis current;
The absolute value of the d-axis current calculated by the dq converter exceeds a predetermined d-axis threshold, and at the same time , the absolute value of the d-axis current calculated by the dq converter and the q-axis current calculated by the dq converter A phase loss detection unit that outputs a phase loss detection signal when a predetermined determination condition including a condition that the ratio of the absolute value is within a predetermined range is satisfied,
A phase-opening detection device. The detected value of the current of each phase supplied to the multiphase AC motor is dq converted to calculate the d-axis current and the q-axis current, and the calculated absolute value of the d-axis current exceeds a predetermined d-axis threshold, at the same time, open phase for detecting the open phase when the calculated d-axis absolute value and a predetermined determination condition, including the ratio of the absolute value of q-axis current on a condition that is within a predetermined range of current are met Detection method.

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