JP2015061341A - Stepping motor failure detection circuit, stepping motor drive unit, and stepping motor drive system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stepping motor failure detection circuit for which a logic circuit measuring detection timing is not required.SOLUTION: The stepping motor failure detection circuit 400, having a comparator circuit 450 for detecting failure in a stepping motor by comparing a detected signal to a failure determination value, includes an integration circuit 420 on the input side of the comparator circuit.

Description

  The present invention relates to a stepping motor failure detection circuit, a stepping motor drive device, and a stepping motor drive system.

  A stepping motor (hereinafter sometimes abbreviated as a motor) is a synchronous motor that operates by supplying a pulse current to the motor and controlling the rotational speed and direction. It is also referred to as a pulse motor, and accurate positioning control can be realized with a simple circuit configuration. Therefore, it is often used for positioning devices.

  11A and 11B are diagrams showing a general stepping motor, where FIG. 11A is a connection diagram, FIG. 11B is a drive pulse waveform diagram when 2-phase excitation bipolar drive is performed, and FIG. 11C is a drive pulse waveform when 1-phase excitation bipolar drive is performed. It is. As shown in (b) and (c), a drive control pulse current is passed through the winding (hereinafter also referred to as a coil). Each time such a current is applied, the rotor rotates by a predetermined step angle.

  In order to detect a coil failure in a two-phase stepping motor, generally, a logic circuit that measures drive timing from the pulse width, duty, and drive start command of a drive pulse is used. Timing is measured by a logic circuit, and failure detection is performed at the timing of the center or peak of the drive pulse. The reason for measuring the timing is that there is a period in which no current flows because the phase in which the current flows is switched when the motor is driven.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-259545) discloses an apparatus that detects the disconnection of an actuator by comparing the value of an actuator current controlled by a control signal with a disconnection determination value. A parameter whose value is larger than the noise peak value at the time of disconnection and set to 75% or less of the maximum absolute value of the actuator current, and the parameter of the control signal makes the absolute value of the actuator current equal to or greater than the disconnection judgment value In addition, it is described that an abnormality occurs when the comparison result of the actuator current value and the disconnection determination value satisfies a predetermined disconnection determination condition.

  Since Patent Document 1 discloses an actuator for disconnection detection, there is no description of measuring the timing of failure detection.

JP 2003-259545 A

  When detecting a failure such as a disconnection or a short circuit of a motor coil while the motor is being driven, a logic circuit for measuring the detection timing is required, and the circuit scale increases. Moreover, there is a possibility that the detection timing is shifted due to the L and C components and the detection cannot be performed correctly.

  The reason is as follows. When detecting a failure of a coil, a pulse current flowing through the coil is converted into a voltage and compared with a failure determination value (hereinafter sometimes referred to as a threshold) to detect a disconnection or a short circuit. As described in 11, the phase (Phase) through which the pulse current flows is switched and driven. Therefore, there is a period during which no current flows, such as during phase switching. At the timing when this current is not flowing or when the rise of the pulse current is delayed due to the L component of the coil, the voltage falls below the threshold and cannot be detected correctly.

  For this reason, the existing circuit uses a logic circuit that measures the detection timing, and performs detection during the period in which the current flows.

  An object of the present invention is to provide a stepping motor failure detection circuit, a stepping motor drive device, and a stepping motor drive system that do not require a logic circuit for measuring detection timing.

  The present invention is a stepping motor failure detection circuit having a comparator circuit that detects a failure of a stepping motor by comparing a detected signal with a failure determination value, wherein an integration circuit is provided on the input side of the comparator circuit. Is a stepping motor failure detection circuit.

  The present invention also provides a stepping motor drive apparatus comprising the stepping motor failure detection circuit, a stepping motor drive circuit that drives the stepping motor, and a stepping motor drive control circuit that controls the stepping motor drive circuit.

  The present invention is also a stepping motor drive system having a stepping motor driven by the stepping motor driving device.

  According to the present invention, a logic circuit for measuring the failure detection timing is not required, and the stepping motor failure detection circuit can be greatly simplified.

1 is a block diagram showing a stepping motor drive system including a stepping motor failure detection circuit according to a first embodiment of the present invention. It is a block diagram which shows the redundant winding type 2 phase stepping motor drive system containing the stepping motor failure detection circuit of 2nd Embodiment of this invention. It is a circuit diagram which shows a general stepping motor failure detection circuit. It is a circuit diagram which shows the stepping motor failure detection circuit of 2nd Embodiment of this invention. It is a detection waveform diagram at the time of one-side disconnection, double-side disconnection, normal operation, and short circuit of the redundant winding stepping motor. It is a figure which shows the detection voltage in the case where there is no integration circuit in the drive control pulse of a motor, drive current, and the failure detection circuit 401, and when there exists. It is a circuit diagram which shows the constant current circuit used in 2nd Embodiment of this invention. It is a circuit diagram which shows the stepping motor failure detection circuit of 3rd Embodiment of this invention. It is a block diagram which shows the stepping motor drive control circuit used in 3rd Embodiment of this invention. It is a circuit diagram which shows the constant current circuit used in 4th Embodiment of this invention. 2A and 2B are diagrams showing a general stepping motor, in which FIG. 1A is a connection diagram, FIG. 2B is a drive pulse waveform diagram of two-phase excitation bipolar drive, and FIG. 2C is a drive pulse waveform diagram of one-phase excitation bipolar drive.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a stepping motor drive system 10 including a stepping motor failure detection circuit according to a first embodiment of the present invention.

  A stepping motor drive circuit 200 (hereinafter sometimes abbreviated as a drive circuit) receives a control signal from a stepping motor drive control circuit 300 (hereinafter also abbreviated as a drive control circuit), and causes the two-phase excitation stepping motor 100 to operate. To drive. The stepping motor failure detection circuit 400 (hereinafter sometimes abbreviated as a failure detection circuit) includes a capacitor 4010, a resistor 4030, and a comparator circuit 450. The capacitor 4010 is inserted between the input terminal of the failure detection circuit 400 and the ground. Reference numeral 4030 denotes a resistor. The integrating circuit 420 is configured by the resistor 4030 and the capacitor 4010.

  The resistor 4030 is newly inserted, or when an amplifier or the like is inserted between the input terminal of the failure detection circuit 400 and the comparator 450, if a resistor is added to the output side of the amplifier or the like, the resistor is used, or If only a resistance component such as wiring between the drive control circuit 300 and the failure detection circuit 400 is sufficient, the resistance component is used. These may be combined.

  A signal detected from the drive circuit 200 is input to the integration circuit 420. For example, the detection signal is obtained by converting a pulse current flowing in the coil into a voltage.

  The output of the integrating circuit 420 is input to the comparator circuit 450, and the comparator circuit 450 compares the output value of the integrating circuit 420 with the failure determination value Ref. As a result of the comparison, when it is determined that there is a failure such as a broken coil, a failure detection status signal 451 is output.

  In the two-phase excitation bipolar drive shown in FIG. 11, there is a timing when the drive current does not flow when the phases are switched as described above. Without the integration circuit 420, the detection signal detected at this timing falls below the failure determination value, and erroneously determines that a failure has occurred. Moreover, there is a possibility that the detection timing is shifted due to the L component of the coil and cannot be detected correctly. At the timing when current does not flow or when the rise of the pulse current is delayed due to the L component of the coil, the voltage falls below the threshold value and cannot be detected correctly.

  However, in this embodiment, the integration circuit 420 delays the time taken for the detection signal to drop during phase switching. If the time constant RC of the integrating circuit 420 is set appropriately, a value close to the signal during the period in which the drive current is flowing can be maintained, and as a result, erroneous detection at the time of phase switching can be prevented. Without the integration circuit 420, it is necessary to calculate the timing that becomes the center of the drive pulse from the set pulse width, duty, and drive instruction timing, and to latch the failure detection status signal. is necessary. If you do not want to use a complicated logic circuit, it was detected when the motor stopped.

On the other hand, in the present embodiment, since disconnection can be detected regardless of the pulse width, duty, and drive instruction timing, a complicated logic circuit is unnecessary, and the circuit can be greatly simplified and reduced in cost. Even when the motor is being driven, failure detection can be performed without considering the timing.
(Second Embodiment)
FIG. 2 is a block diagram showing a redundant winding type two-phase stepping motor drive system including a stepping motor failure detection circuit according to a second embodiment of the present invention.

  This system includes a redundant winding type two-phase stepping motor 101, a stepping motor drive circuit 201 for driving the motor 101, a stepping motor drive control circuit 301 for controlling the stepping motor drive control circuit 201, and a failure detection circuit for detecting disconnection of the motor 101. 401, a constant current circuit 500 for supplying a constant current control signal (described later) to the FETs 9 and 10. The drive circuit 201 is a two-system H-bridge circuit composed of an A-phase bridge circuit and a B-phase bridge circuit.

  As shown in FIG. 2, FET 1 (Field E (Field Effect Transistor)) and FET 2 are connected in series between a power supply Vcc and a first connection point 2001, and FET 3 and FET 4 are connected in series in parallel with this, A first redundant coil of the motor is connected between the connection point of FET2 and the connection point of FET3 and FET4 to constitute an A-phase H bridge circuit.

  Similarly, FET5 and FET6 are connected in series between the power supply Vcc and the second connection point 2002, FET7 and FET8 are connected in series in parallel with this, the connection point between FET5 and FET6, and the connection between FET7 and FET8. A B-phase H bridge circuit is configured by connecting the second redundant coil of the motor between the points.

  Two-phase excitation bipolar drive is performed by the A-phase and B-phase H bridge circuits.

  3 and 4 are circuit diagrams showing a general failure detection circuit and a failure detection circuit of the present embodiment, respectively.

  In the present embodiment, disconnection of one winding of two windings (two to provide redundancy), disconnection of both windings, and short-circuiting of the winding are detected. FIG. 5 shows detected voltage waveforms when one side is disconnected, both sides are disconnected, normal, and short-circuited. The detection threshold 1 at the time of one-side disconnection (hereinafter referred to as threshold 1) is Vthr1, the detection threshold at the time of disconnection at both ends (hereinafter referred to as threshold 2) is Vthr2, and the detection threshold at short-circuit (hereinafter referred to as threshold 3) is Vthr3.

  The threshold value 1 (Vthr1) is a voltage that is slightly higher than the voltage obtained by subtracting the voltage drop due to the coil, the instrumentation cable, and the drive circuit in the state where one side of the redundant winding is disconnected from the upstream drive voltage Vcc. A voltage sufficiently close to 0V than threshold 1 is threshold 2 (Vthr2), and a voltage obtained by subtracting a voltage drop due to the coil, instrumentation cable, and drive circuit in a normal state from Vcc and a voltage higher than the middle of Vcc are threshold 3 (Vthr3), when the detected voltage is between threshold value 1 and threshold value 2, one side disconnection of the redundant winding, when below threshold value 2, both sides of the redundant winding are disconnected, and when it exceeds threshold value 3, the coil short fault to decide. The normal value is between the threshold 1 and the threshold 3.

  When the FETs 1, 4, 5, and 8 are turned on in the drive system of this embodiment, a current flows as in Phase 1 of the two-phase excitation bipolar drive shown in FIG. Next, when all the FETs are turned OFF and then FETs 3, 2, 5, and 8 are turned ON, a current flows as in Phase2. Similarly, when FETs 3, 2, 7, and 6 are turned on, a current flows like Phase 3, and when FETs 1, 4, 7, and 6 are turned on, a current flows like Phase 4. By repeating Phases 1 to 4, the motor rotates. In FIG. 2, a p-type FET is used.

  The control waveform at this time is the same as the drive control pulse waveform shown in FIG. FIGS. 6A and 6B are diagrams showing detected voltages when the motor drive control pulse, the drive current, and the failure detection circuit 401 have no integration circuit. The current flowing in the coil of the motor 101 becomes like the drive current shown in FIG. 6, and the input voltage Vin to the comparator of the failure detection circuit is high following the current like the detection voltage (no integration circuit) shown in FIG. Become.

  Since the current flowing through the coil once drops to 0 ampere when the phase is switched, the value of Vin also drops to 0 V without the integration circuit, and falls below the threshold values Vthr1 and Vthr2. Therefore, if there is no logic circuit for timing, a false detection will occur.

  In the present embodiment, the integration circuit slows down the input voltage Vin even during a period in which no current flows at the time of phase switching, and the next pulse is input before it falls. Therefore, the voltage waveform can maintain a voltage exceeding the threshold value Vthr1, as shown by the detection voltage (with an integration circuit) in FIG.

  When one side of the redundant winding is disconnected, the resistance value of the coil is doubled, and the voltage drop due to the coil increases when a constant current is passed. Therefore, the detection voltage Vin decreases as in the case of one-side disconnection in FIG. The detection voltage Vin is compared with Vthr1 by the comparator Comp1, and disconnection detection is performed.

  When Vin exceeds Vthr1 (normal), the output of the comparator Comp1 becomes Lo. On the other hand, when the detection voltage falls below Vthr1 (one-side disconnection), the output of the comparator Comp1 becomes Hi.

  Similarly, when both sides are disconnected, Vin does not flow to the input part of the failure detection circuit, so Vin becomes approximately 0V. When Vin is higher than Vthr2, the output of the comparator Comp2 is Lo, and when Vin is lower than Vthr2 (both sides are disconnected), the output of the comparator Comp2 is Hi.

  Further, when the coil is short-circuited, the voltage drop is reduced contrary to the case of disconnection, so Vin becomes higher than that in the normal state. When Vin is lower than Vthr3 (normal), the output of Comp3 is Lo, and when Vin is higher than Vthr3, the output of Comp3 is Hi.

  The voltage of the FET 9 connected to the first connection point 2001 in FIG. 2 and the voltage of the FET 10 connected to the second connection point 2002 change as described in FIG. 5 depending on the state of disconnection or short circuit of the coil. The failure detection circuit performs detection in comparison with threshold values 1, 2, and 3.

  Thereby, disconnection can be detected even while the motor is being driven, and the failure detection circuit can be simplified and reduced in cost.

  Here, the failure detection circuit will be described. FIG. 3 shows a general stepping motor failure detection circuit 402 when the stepping motor is driven by two-phase excitation bipolar. FIG. 4 shows the failure detection circuit 403 of the present embodiment.

  First, FIG. 3 will be described. The motor is driven by switching the direction of the current flowing through each phase. The failure detection circuit 402 monitors the voltages at the first connection point 2001 and the second connection point 2002 of the drive circuit 201, amplifies them by the non-inverting amplifier OP31, and then uses the comparators Comp1, Comp2, and Comp3 to set the threshold values Vthr1, Vthr2, Compare with Vthr3.

  If it is between the threshold value Vthr1 and the threshold value Vthr2, it is determined that the redundant winding is broken on one side, if it is below the threshold value Vthr2, it is broken on both sides, and if it is above the threshold value Vthr3, it is determined to be short.

  The threshold Vthr1 is generated by dividing the constant voltage V1 by resistors R2 and R3, and is input to the non-inverting input terminal of the comparator Comp1. The threshold values Vthr2 and Vthr3 are generated in the same manner and input to the comparators Comp2 and Comp3, respectively.

  When the failure detection circuit 402 in FIG. 3 determines that one-side disconnection occurs, the buffer Buff1 connected to the output of the comparator Comp1 outputs a one-side disconnection detection status signal. Similarly, if it determines that both-side disconnection occurs, the comparator Comp2 determines that both-side disconnection status signal. Comp3 outputs each failure status signal: Hi as a short-circuit status signal.

The detection voltage Vin input to the comparator is the difference between the voltage value of the drive voltage Vcc and the voltage drop caused by the impedance of the motor coil, the drive circuit, and the instrumentation wiring (Equation 1). The threshold value Vthr is a voltage of V1, a constant of R2 and R3, and is set as shown in (Expression 2). Note that Vcc in (Equation 1) is the voltage value of the power supply Vcc in FIG. 2, i is the current value flowing through the coil, r1 is the ON resistance value per FET 1 to 8, r2 is the coil impedance, and r3 is the drive circuit. ~ Resistance value per instrument wiring between motors. V1, R2, and R3 in (Formula 2) correspond to V1, R2, and R3 in FIG. 3, respectively.
(Formula 1) Vin = Vcc- {i (2r1 + r2 + 2r3)}
(Formula 2) Vthr = V1 * R3 / (R2 + R3)
In the present embodiment, as shown in FIG. 4, a capacitor C1 is added between the inverting input terminal of the comparator and GND, and the integrating circuit 430 is composed of the resistor R32 originally provided on the output side of the non-inverting amplifier OP41 and the added C32. Is configured. If the time constant of the integration circuit 430 is set appropriately, the time during which the voltage input to the comparator falls can be extended.

  FIG. 7 is a circuit diagram showing a constant current circuit 500 used in this embodiment. A constant current detection voltage A is input to the non-inverting input side of a non-inverting amplifier circuit (hereinafter simply referred to as non-inverting amplifier circuit OP71) composed of resistors R71, 72 and OP amplifier 71. Further, the reference voltage Vref is input to the non-inverting input side of the differential amplifier circuit OP72, the output voltage of the non-inverting amplifier circuit OP71 is input to the inverting input side, and a constant current control signal is output to the FET 9.

  In the figure, “same as above” means that this block is a similar constant current circuit. A constant current detection voltage A is input to the constant current circuit, and a constant current control signal is output to the FET 10.

The value of the constant current is determined by the voltage value of the reference voltage Vref, the gain of the non-inverting amplifier circuit, and the resistance value of the detection resistor. In the constant current circuit, the voltage applied to the detection resistors R90 and R100 downstream of the FETs 9 and 10 in FIG. 2 (constant current detection voltages A and B, respectively) is amplified by the non-inverting amplifier circuit OP71 and the reference voltage Vref is differentially generated. The current is input to the amplifier circuit OP72, and a constant current control signal is output to the FETs 9 and 10 to pass a constant current. The value of the constant current is as shown in (Equation 3). Here, I is a constant current value, Vref is a reference voltage value, r is a resistance value of a detection resistor, and G is a gain of a non-inverting amplifier circuit. The FETs 9 and 10 are n-type FETs.
(Formula 3) I = Vref / (r * G)
(Third embodiment)
In the two-phase excitation bipolar drive stepping motor, the drive current is zero at the time of stopping when no current is flowing through the motor coil even when the phase is switched. Therefore, the detection voltage of the failure detection circuit is below the threshold value. For example, in the failure detection circuit 403 (FIG. 4) of the second embodiment, the input voltage Vin of the comparator becomes 0V. Then, the outputs of the comparators Comp1 and Comp2 become Hi.

  In order to prevent this, in the stepping motor failure detection circuit 800 of the present embodiment, a status generation circuit 810 is added as shown in FIG. 8, and a failure status is generated by ANDing the drive control signal and the failure status signal.

  Specifically, the OR of the drive control signals (FET1_CNT, FET3_CNT, FET5_CNT, FET7_CNT) is taken, and the AND of each of the Comp1 output and the Comp2 output is taken. Thus, disconnection detection can be normally performed.

FIG. 9 is a block diagram showing a drive control circuit 900 used in this embodiment, which includes a drive logic circuit 950 and eight systems of FET drive circuits 901, 902, 903, 904, 905, 906, 907, and 908. From the FET drive circuits 901-908, for example, a drive signal for the FET 1-8 of the stepping motor drive circuit 201 described in FIG. 2 is supplied. A drive control signal from the drive logic circuit 950 is output to both the FET drive circuit and the status generation circuit 810.
(Fourth embodiment)
When the same current as that in a state in which one of the redundant windings is disconnected is not supplied, the risk of disconnection may increase even in a coil that has not been disconnected. The reason is that when one side of the redundant winding to which the same coil is connected in parallel is disconnected, the current flowing in one coil is twice the current flowing in the normal state. Therefore, from W = R * I ² (W is power consumption, R is coil resistance, I is current), the power consumed by one coil is quadrupled, the amount of heat generation is increased, and the remaining coil is damaged. Will increase.

  In order to prevent this, a constant current circuit 600 shown in FIG. 10 is used. This is a disconnection detection status signal that lowers the value of the reference voltage Vref of the constant current circuit, and can automatically reduce the drive current value.

  In this embodiment, a reference voltage changing circuit 650 is provided to lower the value of the reference voltage Vref. The reference voltage changing circuit 650 includes a transistor Tr601 and resistors R66, R67, R68, and R69. When a disconnection detection status signal is input from the failure detection circuit to the base of the transistor 601, the transistor 601 is turned on, and the reference voltage Vcnt is divided by resistors R66 and R69.

  If the sum of the ON resistance of the transistor 601 and the resistance value of the resistor R69 is made the same as that of the resistor R66, the reference voltage Vref output from the reference voltage changing circuit 650 is halved, and the current value is halved from (Equation 3). Become. For this reason, the value of the current flowing through the coil is halved, and the value of the current flowing through one coil that remains without disconnection remains the same as when it is normal. Thereby, although the driving torque of the motor is reduced, the driving can be continued without applying stress to the remaining coil.

When the disconnection detection status signal is not input to the transistor 601, the reference voltage Vcnt becomes the reference voltage Vref as it is. If Vcnt = Vref, it is the same as the constant current circuit 500 of FIG.
(Other embodiments)
In the above embodiment, an example of two-phase bipolar excitation has been described. However, even in the case of multi-phase excitation such as 1-2-phase excitation and 5-phase excitation, if the timing at which no current flows in the coil at the time of phase switching occurs, this Be subject to invention.

A part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.
(Appendix 1)
A stepping motor failure detection circuit having a comparator circuit for detecting a failure of a stepping motor by comparing a detected signal with a failure determination value, wherein an integration circuit is provided on an input side of the comparator circuit Motor failure detection circuit.
(Appendix 2)
The stepping motor failure detection circuit according to appendix 1, wherein the stepping motor is a multi-phase excitation stepping motor, and the integration circuit delays a detection voltage drop at the time of phase switching of the stepping motor.
(Appendix 3)
The stepping motor failure detection circuit according to appendix 1 or 2, wherein the stepping motor is a redundant winding multi-phase excitation bipolar drive.
(Appendix 4)
The comparator circuit includes: a first comparator that detects whether one side of the redundant winding of the stepping motor is disconnected by comparing with a first failure determination value; and whether both sides of the redundant winding are disconnected (1) to (3) provided with a second comparator for detecting by comparing with a second failure determination value and a third comparator for detecting whether or not a short circuit has occurred by comparing with a third failure determination value The stepping motor failure detection circuit according to any one of claims.
(Appendix 5)
5. A stepping motor failure detection according to any one of appendixes 1 to 4, further comprising a status generation circuit having an AND circuit in which the drive control signal of the stepping motor drive circuit is one input and the other input is the output of the comparator. circuit.
(Appendix 6)
A stepping motor drive apparatus comprising the stepping motor failure detection circuit according to any one of appendices 1 to 5, a stepping motor drive circuit that drives the stepping motor, and a stepping motor drive control circuit that controls the stepping motor drive circuit .
(Appendix 7)
Item 7. The supplementary note 6 wherein when disconnection on one side of the redundant winding is detected, the current supplied to the remaining one of the redundant windings is smaller than the current flowing through the redundant winding when the redundant winding is not disconnected. Stepping motor drive device.
(Appendix 8)
A transistor and a resistor are connected between the stepping motor driving circuit and the ground, and a voltage applied to the resistor is input to a constant current circuit. The constant current circuit supplies a constant current that flows from the input and a reference voltage to the transistor. The stepping motor drive device according to Supplementary Note 6 to be defined.
(Appendix 9)
The stepping motor drive according to appendix 8, wherein a failure status signal from the failure detection circuit is input to the constant current circuit, and when the failure status signal is input, the reference voltage is decreased to reduce the constant current value. apparatus.
(Appendix 10)
A stepping motor drive system comprising the stepping motor drive device according to any one of appendices 6 to 9.
(Appendix 11)
The stepping motor driving device according to any one of appendices 6 to 9, wherein a voltage of the transistor connected to the stepping motor driving circuit is input to the failure detection circuit as the detected signal.
(Appendix 12)
The stepping motor drive circuit is
A first FET and a second FET are connected in series to the power supply terminal and the first connection point, and a third FET and a fourth FET are connected in series in parallel with the first FET and the first FET. Connecting a first drive coil of the stepping motor between a connection point of the second FET and a connection point of the third FET and the fourth FET to form a first bridge circuit;
A fifth FET and a sixth FET are connected in series to the power supply terminal and the second connection point, and a seventh FET and an eighth FET are connected in series in parallel with the fifth FET, and the fifth FET is connected. And connecting the second drive coil of the stepping motor between the connection point of the sixth FET and the connection point of the seventh FET and the eighth FET to form a second bridge circuit,
The stepping motor driving device according to any one of appendices 6 to 9 and 11, wherein two-phase driving is performed by the first and second bridge circuits.

DESCRIPTION OF SYMBOLS 10 Stepping motor drive system 100, 101 Stepping motor 200, 201 Stepping motor drive circuit 300, 301 Stepping motor drive control circuit 400, 402 Stepping motor failure detection circuit 420, 430 Integration circuit 450 Comparator circuit 451 Failure detection status signal 500 Constant current circuit 600 constant current circuit 650 reference voltage change circuit 800 stepping motor failure detection circuit 810 status generation circuit 900 drive control circuit 901, 902, 903, 904, 905, 906, 907, 908 FET drive circuit 950 drive logic circuit 4010 capacitor 4030 resistance

Claims (10)

  A stepping motor failure detection circuit having a comparator circuit for detecting a failure of a stepping motor by comparing a detected signal with a failure determination value, wherein an integration circuit is provided on an input side of the comparator circuit Motor failure detection circuit.   2. The stepping motor failure detection circuit according to claim 1, wherein the stepping motor is a multi-phase excitation stepping motor, and the integration circuit delays a detection voltage drop at the time of phase switching of the stepping motor.   The stepping motor failure detection circuit according to claim 1, wherein the stepping motor is a redundant winding multi-phase excitation bipolar drive.   The comparator circuit includes: a first comparator that detects whether one side of the redundant winding of the stepping motor is disconnected by comparing with a first failure determination value; and whether both sides of the redundant winding are disconnected 3. A second comparator that detects a comparison with a second failure determination value, and a third comparator that detects whether or not a short circuit has occurred by comparing with a third failure determination value. The stepping motor failure detection circuit according to any one of the above.   5. A stepping motor failure according to claim 1, further comprising a status generation circuit having an AND circuit in which the drive control signal of the stepping motor drive circuit is one input and the other input is the output of the comparator. Detection circuit.   A stepping motor drive comprising the stepping motor failure detection circuit according to any one of claims 1 to 5, a stepping motor drive circuit for driving the stepping motor, and a stepping motor drive control circuit for controlling the stepping motor drive circuit. apparatus.   The current supplied to the remaining one of the redundant windings when the disconnection on one side of the redundant winding is detected is set to a value smaller than the current flowing through the redundant winding when the redundant winding is not disconnected. The stepping motor driving device described.   A transistor and a resistor are connected between the stepping motor driving circuit and the ground, and a voltage applied to the resistor is input to a constant current circuit. The constant current circuit supplies a constant current that flows from the input and a reference voltage to the transistor. The stepping motor drive device according to claim 6 defined.   The stepping motor according to claim 8, wherein a failure status signal from the failure detection circuit is input to the constant current circuit, and when the failure status signal is input, the reference voltage is decreased to reduce the constant current value. Drive device.   A stepping motor drive system comprising the stepping motor drive device according to any one of claims 6 to 9.

Images