JP2007097243A - Controller for motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To downsize a controller for motor by operating an abnormality detecting circuit without fail, while suppressing increase in parts count. <P>SOLUTION: This controller is equipped with an FETUH, where the drain terminal is connected to a power source 20, and the source terminal is connected to a U-phase coil, in a phase U out of a phase U, a phase V, and a phase W, an FETUL where the drain terminal is connected to a U-phase coil and the source terminal is grounded, an IC19a which controls the opening and closing, being connected to the gate terminal of each FET, a first diode 21 and a first capacitor 22, whose one end each is connected to the intermediate between the source terminal of the FETUH and the drain terminal of the FETUL and whose other ends are connected to the power source 20, and an abnormality detecting circuit 18 which corresponds to the first diode 21 via the second diode 23. This can surely make the abnormality detecting circuit 18 operate by applying high control voltage to the abnormality detecting circuit 18, while suppressing the increase in parts count, and also the controller 14 can be made small. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor control device including a plurality of phase coils.

  In general, brushless motors, which exist as a type of motor, have no mechanical contact parts such as brushes and commutators compared to motors with brushes. Applications are being expanded with the advantages. As such a brushless motor control device, for example, a technique disclosed in Patent Document 1 is disclosed.

  According to this prior art, a control voltage is generated for a power supply side switching element (power supply side control element) provided corresponding to each of the U phase, V phase and W phase for controlling a three-phase brushless motor. Therefore, a bootstrap circuit is provided corresponding to each of the U phase, the V phase, and the W phase.

On the other hand, there is an abnormality detection circuit for detecting an abnormality of the brushless motor. This abnormality detection circuit includes a shunt resistor and an operational amplifier for detecting a current flowing through the brushless motor between the brushless motor and the power source. I have. The operational amplifier is driven with a control voltage higher than the power supply voltage, and a charge pump circuit is used to obtain a high control voltage for driving the operational amplifier.
JP 2005-51926 A

  However, according to the above-described prior art, a charge pump circuit having a complicated configuration is used to reliably operate an abnormality detection circuit including an operational amplifier that is driven with a control voltage higher than the power supply voltage. There are problems such as an increase in the size of the control device and a difficulty in downsizing the control device.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a motor capable of reliably operating an abnormality detection circuit while suppressing an increase in the number of components and reducing the size of a control device. It is to provide a control device.

  The motor control device of the present invention is a motor control device that controls a motor having a plurality of phase coils, each of which is connected between a corresponding phase coil and a power source, A ground-side switching element connected between a corresponding phase coil and a ground terminal; and a control unit that controls opening and closing of the power-supply-side switching element of each phase and the ground-side switching element of each phase at a predetermined timing; A bootstrap circuit for boosting a control voltage applied from the control unit to the power supply side switching element of each phase by a first diode and a capacitor, and a second diode connected to the bootstrap circuit. An abnormality detection circuit that operates by a control voltage supplied from the bootstrap circuit and detects an abnormality of the motor. The features.

  In the motor control apparatus according to the present invention, the abnormality detection circuit detects an abnormality from a change in a current value flowing through the motor.

  In the motor control device of the present invention, when the motor is started, the control unit charges the capacitor by simultaneously closing the ground-side switching elements of the respective phases, and then simultaneously opens the ground-side switching elements. The charging voltage of the capacitor is taken in, and the power supply side switching element of each phase is simultaneously closed to charge the capacitor again, and the added voltage of the charging voltage and the charging voltage taken into the control unit is This is applied to the abnormality detection circuit via a diode.

  In the motor control apparatus of the present invention, the motor is a brushless motor.

  According to the present invention, since the abnormality detection circuit is connected to the capacitor via the second diode, the control voltage can be applied from the capacitor to the abnormality detection circuit only by adding the second diode. While suppressing an increase in the number of parts, the abnormality detection circuit can be reliably operated by applying a control voltage to the abnormality detection circuit. Further, since only the second diode needs to be added, the control device is not hindered in size reduction.

  According to the present invention, the abnormality detection circuit detects an abnormality from a change in the current value flowing through the motor. Therefore, according to the current value flowing through the motor, the motor failure determination due to the disconnection or short circuit of the harness in the motor. And the reliability of the control device can be improved.

  According to the present invention, since the power supply side switching element and the ground side switching element are controlled so that a high control voltage can be obtained when the motor is started, a stable control voltage can be applied to the abnormality detection circuit.

  According to the present invention, a brushless motor can be used as the motor. In this case, the mechanical contact portion can be eliminated, and the life of the motor can be extended.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 6. 1 is a circuit diagram showing a motor control device according to the present invention, FIG. 2 is a drive circuit diagram constituting the control device of FIG. 1, and FIG. 3 is a FET bridge circuit diagram constituting the control device of FIG. 4 is an abnormality detection circuit diagram for detecting an abnormality of the motor constituting the control device of FIG. 1, and FIG. 5 is a pattern of opening / closing (OFF / ON) control for the FET for obtaining a high control voltage when the motor is started. FIG. 6 is a time chart showing motor logic signals.

  A brushless motor 10 as a motor indicated by a broken line in FIG. 1 includes a rotatable magnet rotor 10a having N poles and S poles alternately at equal intervals in the circumferential direction, for example, 4 poles, and the magnet rotor 10a therein. A cover (not shown) which is accommodated in a non-contact manner and provided with a three-phase coil, and a hall element 11 as a position detector which accommodates the stator and detects the rotation angle of the magnet rotor 10a. (Not shown). Here, three Hall elements 11 are provided according to each phase, and are provided on the cover at 60 ° intervals along the circumferential direction so as to face the magnet rotor 10a in the axial direction. Further, each harness 12 in the three-phase coil and each harness 13 in the hall element 11 are connected to the control device 14, respectively.

  As shown in FIGS. 1 to 4, the control device 14 is provided with a CPU 15, a drive circuit 16, an FET bridge circuit 17, and an abnormality detection circuit 18 therein.

  A command signal from an operation switch or the like (not shown) that is operated by an operator is input to the CPU 15, and the CPU 15 executes predetermined arithmetic processing in response to the input of the command signal, The instruction signals to the U-phase coil, V-phase coil and W-phase coil of the brushless motor 10 are alternately output. Further, the hall current from the three hall elements 11 provided in the brushless motor 10 is input to the CPU 15 via each harness 13, and the CPU 15 detects the hall current by detecting the hall current. The magnetic pole change in the rotation direction of the magnet rotor 10a is detected, and thereby the rotation angle (rotation position) of the magnet rotor 10a is detected. Furthermore, an abnormality detection circuit 18 that detects an abnormality of the brushless motor 10 is connected to the CPU 15, and the CPU 15 determines whether or not the brushless motor 10 is in an abnormal state according to a current signal from the abnormality detection circuit 18. To come to judge.

  The drive circuit 16 includes control units (IC) 19a and 19b each having eight pins for generating and applying a gate voltage (control voltage) to the six FETs provided in the FET bridge circuit 17. , 19c are provided. The power supply voltage (12 V in the present embodiment) from the power supply 20 is input to the first pin of each of these ICs 19a, 19b, and 19c, and the second and third pins have An instruction signal from the CPU 15 is input.

  A first diode 21 is provided between the power supply 20 and each of the 8th pins of the ICs 19a, 19b, and 19c. The first diode 21 flows current only from the power supply 20 side to the 8th pin. A first capacitor 22 is provided between the pins. The anode of the second diode 23 is connected to the downstream side of the 8th pin of each IC 19a, 19b, 19c, and the abnormality detection circuit 18 is connected to the cathode side of the second diode 23. Here, the first diode 21 and the first capacitor 22 constitute a bootstrap circuit in the present invention.

  The gate terminals of FETUH, FETVH, and FETWH provided in the FET bridge circuit 17 are connected to the seventh pin of each IC 19a, 19b, 19c via a resistor 24. A resistor 25 and a Zener diode 26 are provided in parallel between the 7th pin and the 6th pin, and the U phase coil, the V phase coil, and the W phase coil in the brushless motor 10 are provided by the resistor 25 and the Zener diode 26. A stable voltage can be applied.

  The U-phase coil, the V-phase coil and the W-phase coil of the brushless motor 10 are connected in that order to the 6th pin of each IC 19a, 19b and 19c, and the source terminals of the FETUH, FETVH and FETWH are connected. Further, the drain terminals of FETUL, FETVL and FETWL provided in the FET bridge circuit 17 are connected.

  The gate terminals of FETUL, FETVL, and FETWL are connected to the fifth pin of each IC 19a, 19b, 19c via a resistor 27. A resistor 25 and a Zener diode 26 are provided in parallel between the fifth pin and the ground terminal GND, and a stable voltage is applied to the FETUL, FETVL, and FETWL by the resistor 25 and the Zener diode 26. I can do it.

  Capacitors 28 are provided between the first and fourth pins of the ICs 19a, 19b, and 19c, and the fourth pins are connected to the ground terminal GND.

  The FET bridge circuit 17 is provided with six FETs (FETUH, FETVH, FETWH, FETUL, FETVL, and FETWL) as switching elements that are opened / closed (OFF / ON) by a control voltage load applied to the gate terminal. FETUH, FETVH and FETWH constitute a power supply side switching element in the present invention, and FETUL, FETVL and FETWL constitute a ground side switching element in the present invention. Here, for example, if the sign attached to the end of the FET is UH, it indicates that the FET is on the HIGH side (power supply side) of the U phase, and if it is WL, it is the LOW side (grounding side) of the W phase. ).

  A power supply 20 is connected to the drain terminals of the FETUH, FETVH, and FETWH via a shunt resistor 29 that constitutes the abnormality detection circuit 18, and the source terminals of the FETUL, FETVL, and FETWL are connected to the ground terminal GND. Thus, one end side of the brushless motor 10 is connected to the power source 20 and the other end side of the brushless motor 10 is connected to the ground terminal GND.

  The abnormality detection circuit 18 includes a shunt resistor 29, a first operational amplifier 30 that is driven by application of a control voltage equal to or higher than the power supply voltage, and a second capacitor that is charged with a control voltage for driving the first operational amplifier 30. 31.

  The upstream connection portion of the shunt resistor 29 is connected to the power supply 20, and the downstream connection portion is connected to the drain terminals of the FETUH, FETVH, and FETWH. One input part (non-inverting input part) of the first operational amplifier 30 is connected between the shunt resistor 29 and the power supply 20, and the other input part (inverting input part) is the shunt resistor 29, FETUH, FETVH, and FETWH. Is connected between the drain terminal of each other.

  One end of the first operational amplifier 30 and the shunt resistor 29 are connected so that the resistor 32 and the capacitor 33 are in parallel, and the other end of the resistor 32 and the capacitor 33 is grounded. It is connected to the terminal GND. One end side of the inverting input section of the first operational amplifier 30 and the shunt resistor 29 are connected so that the resistor 34 and the capacitor 35 are in parallel, and the other end side of the resistor 34 and the capacitor 35 is the first side. Are connected to the output section of the operational amplifier 30. One end side of the resistor 36 is connected to the output section of the first operational amplifier 30, and the other end side of the resistor 36 is connected to the ground terminal GND.

  The cathode of the second diode 23 provided in the drive circuit 16 is connected to the first operational amplifier 30 and the second capacitor 31, and the control voltage from the drive circuit 16 is connected to the second capacitor 31. It is supposed to be charged. The charging voltage (control voltage) charged in the second capacitor 31 is discharged toward the first operational amplifier 30.

  The output section of the first operational amplifier 30 is connected to the inverting input section of the second operational amplifier 39 via two resistors 37 and 38. One end side of the capacitor 40 is connected between the inverting input portion of the second operational amplifier 39 and the resistor 38, and the other end side of the capacitor 40 is connected to the ground terminal GND. A non-inverting input portion of the second operational amplifier 39 is connected between the two resistors 37 and 38 via the resistor 41 and the capacitor 42, and the second operational amplifier 39 is connected between the resistor 41 and the capacitor 42. Connected to the output. The output unit of the second operational amplifier 39 is connected to the CPU 15 and is connected to the ground terminal GND via the resistor 43.

  As described above, the output unit of the first operational amplifier 30 is connected to the CPU 15 via the second operational amplifier 39, and the CPU 15 determines the abnormality of the brushless motor 10 according to the output signal from the first operational amplifier 30. It comes to detect. The output signal of the first operational amplifier 30 is the actual current value that actually flows to the brushless motor 10 obtained from the downstream connection portion of the shunt resistor 29 and the brushless motor 10 from the power source 20 obtained from the upstream connection portion of the shunt resistor 29. It is obtained by comparison with the current value (command current value) energized to the current. When the difference current value between the actual current value and the command current value is compared with a threshold value set in advance in the first operational amplifier 30, when a predetermined value deviates from the threshold value, the brushless Assuming that the motor 10 is abnormal, an output signal is output from the first operational amplifier 30 to the CPU 15.

  Next, the effect | action in this Embodiment comprised as mentioned above is demonstrated, referring FIG. 5 and FIG. The brushless motor 10 according to the present embodiment is assumed to be a vehicle-mounted brushless motor, and the brushless motor 10 is driven by a power supply voltage 12V of the battery. Further, the brushless motor 10 according to the present embodiment employs a so-called bipolar drive 120 ° energizing rectangular wave drive method including six FETs as switching elements, and a Y-connected U-phase coil, V With respect to the phase coil and the W-phase coil, current is supplied to any two coils for driving.

  First, at the time of starting the brushless motor 10, when the IC 19a, 19b, 19c receives a command signal from the CPU 15, the respective gates of the FETUL, FETVL, and FETWL are respectively started from the respective fifth pins of the ICs 19a, 19b, 19c. A control voltage is simultaneously applied to the terminals. Then, as shown in FIG. 5, FETUL, FETVL, and FETWL are ON-controlled (closed control). That is, the LOW side FET of the U phase coil, the LOW side FET of the V phase coil, and the LOW side FET of the W phase coil are simultaneously ON controlled. By the ON control of the three FETs on the ground side, the power supply voltage of 12V is charged to the first capacitor 22 constituting the bootstrap circuit provided corresponding to each of the U-phase coil, the V-phase coil and the W-phase coil. The

  Thereafter, when each IC 19a, 19b, 19c receives another command signal from the CPU 15, the application of the control voltage applied to the gate terminals of the FETUL, FETVL, and FETWL is stopped, whereby the ICs 19a, 19b, 19c A charging voltage of 12V is taken into each IC 19a, 19b, 19c from each 8th pin via the first capacitor 22. Then, as shown in FIG. 5, the control voltage applied to the gate terminals of the FETUL, FETVL, and FETWL is stopped, that is, the FETUL, FETVL, and FETWL are turned off (open control), and simultaneously, the FETUH, FETVH, and The FETWH is ON-controlled (closed control), and the power supply voltage of 12 V is applied again to the first capacitor 22 to be charged.

  Then, the added voltage value 24V (control voltage) of the charging voltage of 12V taken into the ICs 19a, 19b, and 19c and the charging voltage of 12V newly charged in the first capacitor 22 is applied to the second diode 23. Thus, the first operational amplifier 30 is reliably driven by the control voltage of 24V charged in the second capacitor 31 constituting the abnormality detection circuit 18 and charged in the second capacitor 31. By driving the first operational amplifier 30, the abnormality detection circuit 18 that detects an abnormality of the brushless motor 10 can be reliably operated.

  After the operation of each IC 19a, 19b, 19c at the time of starting the brushless motor 10 as described above is finished by the instruction signal from the CPU 15, the operation is shifted to the normal operation of the brushless motor 10. After the transition to the normal operation of the brushless motor 10, the control device 14 sets each IC 19 a, 19 b, 19 c in FIG. 6 according to an instruction signal from the CPU 15 according to the rotation angle of the magnet rotor 10 a due to the Hall current from the Hall element 11. Based on the logic signal shown, the six FETs are controlled to open / close (OFF / ON control) at a predetermined timing. In FIG. 6, the shaded portion indicates that each FET is ON-controlled.

  Here, for example, when the rotation angle of the magnet rotor 10a is between 0 ° and 90 °, the FETUH / FETUL, the FETUH / FETWL, and the FETWH / FETWL are each turned on alternately, that is, the current is sequentially applied to the two coils. The smooth rotation characteristics of the magnet rotor 10a can be obtained. Further, even during normal operation of the brushless motor 10, that is, when the brushless motor 10 is rotated, abnormalities are caused by high-speed opening / closing control of each of the six FETs, that is, by applying a control voltage to the gate terminal of each FET at high speed. The second capacitor 31 constituting the detection circuit 18 can be charged with 24V. As a result, the first operational amplifier 30 can be driven to continuously detect an abnormality in the brushless motor 10.

  When the harness 12 corresponding to each phase of the brushless motor 10 is broken or short-circuited and fails, the actual current value flowing through the brushless motor 10 is greatly different from the command current value obtained from the power supply 20. Thus, the difference current value between the actual current value and the command current value deviates from the threshold value of the first operational amplifier 30. Then, an output signal is output from the first operational amplifier 30 to the CPU 15, and the CPU 15 determines that the brushless motor 10 is in failure due to the input of this output signal (failure signal). When it is determined that there is a failure as described above, in order to notify the operator or the like, for example, an LED or the like may be provided outside and the LED may blink.

  According to the present embodiment configured as described above, the first diode 21 and the first capacitor 22 constituting the bootstrap circuit are connected to the abnormality detection circuit 18 via the second diode 23. A high control voltage can be applied from the bootstrap circuit to the abnormality detection circuit 18 only by adding the second diode 23. Therefore, it is possible to reliably operate the abnormality detection circuit by applying a high control voltage to the abnormality detection circuit while suppressing an increase in the number of parts. Further, since only the addition of the second diode 23 is required, the size reduction of the control device 14 is not hindered. Furthermore, the failure determination of the brushless motor 10 due to disconnection or short circuit of each harness 12 in the brushless motor 10 can be performed by detecting the actual current value of the brushless motor 10, and the reliability of the control device 14 can be improved. it can.

  In addition, since the bootstrap circuit is configured by the first diode 21 and the first capacitor 22 to simplify the structure, it is not necessary to use a charge pump circuit having a complicated structure. The size can be reduced and the cost can be reduced.

  Further, when the brushless motor 10 is started, the ground side switching element and the power source side switching element are controlled so that a high control voltage can be obtained. Therefore, a stable high control voltage is applied to the abnormality detection circuit 18, and Subsequently, the brushless motor 10 can be normally operated.

  Further, since the brushless motor 10 is used as the motor, the mechanical contact portion can be eliminated, and the life of the motor can be extended without maintenance.

  In addition, this invention is not limited to embodiment mentioned above, A various change is possible in the range which does not deviate from the summary. For example, in the above-described embodiment, the second diode 23 is connected to each of the bootstrap circuits connected to the ICs 19a, 19b, and 19c. However, the present invention is not limited to this, and FIG. As shown in the modification, the second diode 23 may be connected to at least one of the ICs 19a, 19b, and 19c (only the V phase in FIG. 7). Note that the control voltage application pattern at that time may be such that ON / OFF control is performed only on the phase (V phase) to which the second diode is connected, as shown in FIG.

  In the above-described embodiment, the brushless motor 10 that drives the vehicle-mounted drive device is assumed. However, the present invention is not limited to this, and is also applicable to, for example, a brushless motor in an IT device such as an HDD. It can be used for any purpose. Furthermore, in the above-described embodiment, the brushless motor 10 is used as the motor. However, the present invention is not limited to this, and can be applied to a brushed motor having a plurality of phase coils.

  In the above-described embodiment, the failure determination of the brushless motor 10 is performed by detecting the actual current value of the brushless motor 10. However, the present invention is not limited to this, for example, with a high control voltage. Needless to say, any abnormality detection circuit that detects an abnormality of the operating motor can be applied to an abnormality detection circuit other than the one that detects the current value of the motor.

It is a circuit diagram which shows the control apparatus of the motor in this invention. It is a drive circuit diagram which comprises the control apparatus of FIG. It is a FET bridge circuit diagram which comprises the control apparatus of FIG. It is an abnormality detection circuit diagram which detects abnormality of the motor which comprises the control apparatus of FIG. It is a figure which shows the pattern of the opening / closing (OFF / ON) control with respect to FET for obtaining a high control voltage at the time of a motor starting. It is a time chart figure which shows the logic signal of a motor. It is a circuit diagram which shows the modification of the control apparatus of the motor in this invention. It is a figure which shows the pattern of the opening / closing (OFF / ON) control of FET in the circuit diagram shown in FIG.

Explanation of symbols

10 Brushless motor (motor)
10a Magnet rotor 14 Control device 15 CPU
16 drive circuit 17 FET bridge circuit 18 abnormality detection circuit 19a, 19b, 19c IC (control unit)
21 First diode (bootstrap circuit)
22 First capacitor (capacitor, bootstrap circuit)
23 2nd diode U phase coil V phase coil W phase coil UH FET (power supply side switching element)
VH FET (Power supply side switching element)
WH FET (Power supply side switching element)
UL FET (Grounding side switching element)
VL FET (ground side switching element)
WL FET (Grounding side switching element)
GND Ground terminal

Claims (4)

A motor control device for controlling a motor having a plurality of phase coils,
A power supply side switching element connected between each corresponding phase coil and the power supply;
A ground-side switching element connected between the corresponding phase coil and the ground terminal;
A control unit that controls opening and closing of the power supply side switching element of each phase and the ground side switching element of each phase at a predetermined timing;
A bootstrap circuit that boosts a control voltage applied from the control unit to the power supply side switching element of each phase with a first diode and a capacitor;
An abnormality detection circuit which is connected to the bootstrap circuit via a second diode and operates by a control voltage supplied from the bootstrap circuit to detect an abnormality of the motor;
A motor control device comprising:   2. The motor control apparatus according to claim 1, wherein the abnormality detection circuit detects an abnormality from a change in a current value flowing through the motor.   3. The motor control device according to claim 1, wherein when the motor is started, the control unit charges the capacitor by simultaneously closing the ground-side switching elements of the respective phases, and then the ground-side switching element. The charging voltage of the capacitor is taken by simultaneously opening the capacitor, and the power supply side switching element of each phase is simultaneously closed to charge the capacitor again, and an added voltage of the charging voltage and the charging voltage taken into the control unit is obtained. The motor control device applying to the abnormality detection circuit via the second diode.   The motor control device according to any one of claims 1 to 3, wherein the motor is a brushless motor.

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