JPH08140393A - Protective circuit for motor drive control circuit - Google Patents

Abstract

PURPOSE: To interrupt the current reliably upon locking of the rotor by providing a first protective circuit for inputting a power OFF signal with a time lag, and a second protective circuit for inputting a power OFF signal in response to a stop signal. CONSTITUTION: If a start signal is provided to a first protective circuit when a rotor is locked, the terminal voltage exceeds the referential potential of a comparator COM1 because no pulse signal is delivered from the output terminal during the charging operation of a capacitor C2. Consequently, the output of the comparator COM1 goes High to turn a transistor Q2 ON and thereby a correction terminal goes Low. As a result, current supply to stator coils L1,..., L3 is interrupted thus interrupting the starting current. On the other hand, a second protective circuit 2 is fed with a stop signal when the rotor is locked and even if the stop current can not be interrupted at the first protective circuit 1, a stop detection circuit IC2 delivers a Low level stop signal and thereby a Low level power OFF signal is fed to the output terminal thus interrupting the stop current reliably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive control circuit for a DC brushless motor, and to a motor drive control circuit protection device having improved safety.

[0002]

2. Description of the Related Art Generally, in a brushless multi-phase DC motor, a rotor including a stator having a stator coil for generating a magnetic field in an excited state and a rotor magnet for obtaining a rotational force by electromagnetic interaction with the magnetic field of the stator coil. A well-known structure is one that has a sensor for detecting the rotational position of the rotor magnet. In such a brushless motor, in many cases, rotation control is performed by an electronic circuit formed on a semiconductor chip, that is, a motor drive control circuit.

In this case, the magnetic field generation timing on the stator side is controlled by detecting the rotational position of the rotor magnet by a sensor, and a Hall element has been conventionally used for this type of sensor. Further, this type of motor drive control circuit is often mounted on a circuit board integrated with the motor, and tends to be integrated into one chip as the product becomes smaller.

FIG. 3 shows an example in which a motor drive control circuit for a three-phase brushless motor is integrated into one chip.
The motor drive control circuit IC1 (for example, model number LB1825 manufactured by Sanyo Electric Co., Ltd.) has output terminals OUT1 to OUT3, which are star-connected three-phase stator coils L1 to L3.
, And three Hall elements H1 to H3 are connected to the positive and negative terminals of the Hall input terminals IN1 to IN3.
A start signal / stop signal (S / S) from the outside is input to the brake command input terminal S / B.

The motor drive control circuit IC1 has a rotation control function of controlling an exciting current supplied to each of the stator coils L1 to L3 on the basis of an output signal of each of the Hall elements H1 to H3 for detecting the rotational position of the rotor. The start mode and the stop mode are selected by a start signal and a stop signal from the outside, respectively. That is, in this case, the start signal is at the low level and the stop signal is at the high level, and the high level of the stop signal is input to the brake command input terminal S / B to select the stop mode.

When a start signal is input when the motor is stopped, a relatively large starting current is supplied to each of the stator coils L1 to L3, whereby acceleration control is performed,
When the motor rotates and the rotation is detected by the Hall elements H1 to H3, the supply of the starting current is ended, the rotation control function is executed, and the predetermined rotation state is maintained. When a stop signal is input during motor rotation, a relatively large stop current for reverse-phase rotation is supplied to the stator coils L1 to L3 instead of the exciting current, whereby brake control is performed. Then, when the rotation speed of the motor falls below the specified value, the supply of this stop current is stopped,
After that, the motor is stopped.

[0007]

Although the operation of the above-mentioned motor drive control circuit IC1 is general,
This kind of drive control circuit IC1 has the following problems.

That is, when the load on the motor suddenly increases and the rotor is locked, for example, when a paper jam occurs in the paper feeding operation in the main motor for the printer, or when the meshing of the gears is disturbed. Alternatively, when the start signal is input to rotate the motor, such as when the rotation of the rotor is artificially restricted, the motor drive control circuit IC1 supplies the starting current to each of the stator coils L1 to L3, but the rotor does not rotate. The starting current does not switch to the exciting current, and this large starting current continues to flow.

Further, since the rotor does not rotate even when the start signal is input, if an abnormality is noticed and a stop signal is input this time, the motor drive control circuit IC1 supplies a stop current to each of the stator coils L1 to L3. Since the rotor has already stopped, it may not be possible to detect that the rotational speed of the rotor has dropped below the specified value, and this large stop current will continue to flow. In this case, although it seems that the motor stop operation is completed only by the factual relationship between the input of the stop signal and the stopped state of the rotor, the stop current actually continues to flow.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to reliably cut off the starting current and the stopping current when the rotor is locked. It is to provide a protection device for a motor drive control circuit.

[0011]

In order to achieve the above object, a motor drive control circuit protection device according to a first aspect of the present invention supplies a coil to a coil based on an output signal of a sensor for detecting a rotational position of a motor. It has a rotation control function to control the excitation current, the start signal and the stop signal select the start mode and the stop mode, respectively, and the start signal when the motor is stopped supplies the starting current to the coil to perform acceleration control, When the rotation detection detects the rotation, the rotation control function is executed to execute the rotation control function.The stop signal is supplied to the coil to supply the stop current to the coil for brake control, and when the motor rotation speed falls below the specified value. It is equipped with a motor drive control circuit that stops the supply of stop current, and a rotation speed detection signal that consists of a pulse signal with a frequency according to the rotation speed of the motor. And when the start signal is input and the rotation speed detection signal is not input within a predetermined delay time when the start signal is input, the motor drive control circuit stops the current supply to the coil after the delay time. A first protection circuit for inputting a power-off signal, and a second protection circuit for detecting a motor stop using the rotation speed detection signal and inputting a power-off signal to the motor drive control circuit by the stop signal. It is characterized by.

In this case, it is desirable that the second protection circuit includes a start compensation circuit that cancels the stop signal when the start signal is input.

In order to achieve the above object, a motor drive control circuit protection device according to a second aspect of the present invention controls an exciting current supplied to a coil based on an output signal of a sensor that detects a rotational position of a motor. It has a rotation control function that controls the start mode and stop mode by the start signal and the stop signal, respectively, and supplies a starting current to the coil by the start signal when the motor is stopped to perform acceleration control and start by detecting the rotation of the motor. Stop the current supply and execute the rotation control function, and supply the stop current to the coil by the stop signal when the motor is rotating to perform the brake control.
A motor drive control circuit that stops the supply of a stop current when the rotation speed of the motor drops below a specified value, a first pulse generation circuit that generates a first pseudo pulse signal when the power is turned on, and a first pulse generation circuit when a stop signal is input. A second pulse generation circuit that generates two pseudo pulse signals; and an inverting circuit that inverts the output signal of the sensor for the output time of each pseudo pulse signal by each pseudo pulse signal from both pulse generation circuits. It is a feature.

In this case, it is preferable that the sensor is composed of a Hall element and the inverting circuit is arranged to invert the polarity of the power source to the Hall element for the output time of each pseudo pulse signal by the input of each pseudo pulse signal. Further, a third pulse generation circuit that generates a power-off signal having a pulse width longer than that of the second pseudo pulse signal when the stop signal is input is provided, and the current supply to the coil is stopped by inputting the power-off signal to the motor drive control circuit. It's even better then.

[0015]

In the motor drive control circuit protection device of the present invention described above, in the case of the first invention, when the start signal is input, the rotation speed detection signal is not input within a predetermined delay time. Since the power-off signal is input to the motor drive control circuit from the first protection circuit, the supply of the start-up current can be stopped by the power-off signal even if the start-up current flows when the rotor is locked. In this case, when the motor starts to rotate normally by the input of the start signal, the rotation speed detection signal corresponding to the rotation speed of the motor is input within the predetermined delay time, so the first protection circuit outputs the power off signal. No rotation is performed, and normal rotation control is performed.

Further, when the stop signal is input because the motor does not rotate when the rotor is locked, the stop current is supplied from the motor drive control circuit, but in the second protection circuit, the rotation output from the motor drive control circuit. Since the motor stop is detected by using the speed detection signal and the power supply off signal is input to the motor drive control circuit by this stop signal, the current supply is surely stopped in the motor stopped state.

If the second protection circuit includes a start compensation circuit that cancels the stop signal when the start signal is input, the second protection circuit receives the start signal when the motor is stopped.
The problem that the protection circuit outputs the stop signal can be avoided, and the motor can be rotated quickly.

Next, in the case of the second invention, the first and second pseudo pulse signals are output from the first and second pulse generation circuits respectively when the power is turned on and the stop signal is input, and the pseudo pulse is output by the inverting circuit. Since the output signal of the sensor is inverted for the output time of the signal, it is possible to create the same situation as if the motor had rotated for a moment. Therefore, even when the rotor is locked, the starting current at the time of starting can be cut by this pseudo rotation, and the stopping current at the time of stop can be cut by detecting the decrease in the rotation speed due to the pseudo rotation.

Here, when a stop signal is input during motor rotation, there is a possibility that an inverted signal due to a pseudo pulse signal may be mixed with the pulse signal of the sensor output to accelerate the rotation of the motor. If a third pulse generation circuit that generates a power-off signal having a pulse width longer than that of the second pseudo pulse signal is provided, current supply to the coil is stopped by inputting the power-off signal to the motor drive control circuit during motor rotation. The acceleration control is avoided.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. It should be noted that the same reference numerals as in the related art indicate the same or corresponding ones.

First, a first embodiment corresponding to the first invention will be described with reference to FIG. In FIG. 1, the FG pulse output terminal F of the motor drive control circuit IC1 (LB1825)
Gout2 outputs a rotation speed detection signal composed of a pulse signal having a frequency corresponding to the rotation speed of the motor formed by using one of the signals of the Hall elements H1 to H3, and this rotation speed detection signal is the first protection. It is input to the circuit 1.
The first protection circuit 1 includes a capacitor C1, a switching transistor Q1, a charging / discharging capacitor C2, a comparator COM1, an open collector type transistor Q2, etc., and a start signal / stop signal (S /
S) is input to the base of the transistor Q1 via the backflow prevention diode D1. Where capacitor C
No. 2 is set so that charging is performed slowly and discharging is performed rapidly by setting the resistance value of the resistor R1 connected to the power supply terminal.

When the rotation speed detection signal consisting of a pulse signal having a frequency corresponding to the rotation speed of the rotor is input to the first protection circuit 1 from the output terminal FGout2 during motor rotation, this pulse signal is passed through the capacitor C1 to the transistor Q.
1 is switched, and charging / discharging of the capacitor C2 is repeated. Therefore, the terminal voltage of the capacitor C2 is
1, a certain reference potential defined by R2 cannot be exceeded,
The output of the comparator COM1 becomes low level, and the transistor Q2 remains off. The collector of the transistor Q2 is connected to the frequency characteristic correction terminal FC of the motor drive control circuit IC1. Motor drive control circuit IC1
Is the stator coil L when this correction terminal FC is at high level
1 to L3 are supplied with current, and when at low level, the supply of current to the stator coils L1 to L3 is stopped. Therefore, since the correction terminal FC at the time of motor rotation becomes high level, the rotation of the motor is continued.

On the other hand, when the start signal (low level) is input when the motor is stopped, the transistor Q1 is turned off, so that the capacitor C2 is only charged. In this case, since the charging operation of the capacitor C2 is performed gently, when the rotor normally rotates by the start signal, the pulse signal of the rotation speed detection signal is output from the output terminal FGout2 before the terminal potential of the capacitor C2 reaches the reference potential. Therefore, the rotation speed detection signal causes the transistor Q1 to perform a switching operation, the capacitor C2 is repeatedly charged and discharged, and its terminal potential does not rise.
The output of the comparator COM1 is low level, the transistor Q2 is off, the correction terminal FC is high level, and the rotation of the motor is continued.

When the start signal is input when the rotor is locked, a pulse signal is not output from the output terminal FGout2 during the charging operation of the capacitor C2, so that the terminal potential of the capacitor C2 finally exceeds the reference potential of the comparator COM1. The output of the comparator COM1 becomes high level, the transistor Q2 is turned on, and the correction terminal F
C becomes low level, the current supply to the stator coils L1 to L3 is stopped, and the starting current is cut off.

When a stop signal (high level) is input to the first protection circuit 1, the transistor Q1 is turned on and the capacitor C2 discharges. Therefore, the comparator COM is turned to low level and the transistor Q2 is turned on. A stop current is supplied to the stator coils L1 to L3. However, if a stop signal is input when the rotor is locked, there is a problem that this stop current cannot be cut off. Therefore, the second protection circuit 2 is provided.

That is, the second protection circuit 2 has the output terminal F
A stop detection circuit IC2 that detects a stop of the motor using a rotation speed detection signal from Gout2 is provided, and a transistor Q3 and an open collector type transistor Q4 that switch depending on the presence or absence of a stop signal (low level) from the stop detection circuit IC2. It is configured with. The collector of the transistor Q4 is connected to the FG amplifier output terminal FGout1 of the motor drive control circuit IC1. When the motor drive control circuit IC1 inputs a low-level power-off signal to the output terminal FGout1, the motor drive control circuit IC1 stops power supply to the internal circuits and the stator coils L1 to L3.

Therefore, even if the stop signal is input when the rotor is locked and the stop current cannot be cut off in the first protection circuit 1, the output of the stop detection circuit IC2 becomes a low level stop signal at this time, so that the transistor Q3 Is off, the transistor Q4 is on, and the output terminal FGou
A low-level power-off signal is input to t1, and the stop current can be cut off without fail.

If the rotor is rotating, the stop detection circuit I
Since C2 does not detect the stop and its output becomes high level, the transistor Q3 is turned on, the transistor Q4 is turned off, and the power is not turned off.

Here, when the start signal is input when the motor is stopped, the output of the stop detection circuit IC2 becomes a low level stop signal at this time, and therefore the second protection circuit 2 keeps the power off and cannot start. Defect occurs. Therefore, the second protection circuit 2 includes a start compensation circuit 3 that cancels the stop signal from the stop detection circuit IC2 when the start signal is input. The start-up compensation circuit 3 includes a transistor Q5 to which a start signal / stop signal is input at the base and a backflow prevention diode D2, and the output is input to the base of the transistor Q3.

When a start signal is input when the motor is stopped, the transistor Q5 is turned off because it is at a low level, the voltage 5V at the power supply terminal is input to the transistor Q3 through the diode D2, and the stop detection circuit IC2 stops the operation. The signal is canceled, the transistor Q3 is turned on, the transistor Q4 is turned off, the aforementioned power-off state is avoided, and the start control is performed.

Next, a second embodiment corresponding to the second invention will be described with reference to FIG. In this embodiment, the polarity of the power supply to the Hall elements H1 to H3 connected to the motor drive control circuit IC1 (LB1825) is instantly reversed at the time of power supply and at the time of stop, thereby creating the same situation as that of the rotor being rotated. It is intended to eliminate the above-mentioned problems when the rotor is locked.

That is, the first pulse generation circuit 4 for generating the first pseudo pulse signal when the power is turned on, the second pulse generation circuit 5 for generating the second pseudo pulse signal when the stop signal is input, and the both pulse generation circuit 4 Inversion circuit 6 for inverting the output signals of Hall elements H1 to H3 for the output time of each pseudo pulse signal by each pseudo pulse signal from 5
It has and.

The first pulse generation circuit 4 connects two integrator circuits 7 and 8 having different time constants to the 12V power supply terminal, makes the rise of each integrated output when the power is turned on different, and outputs the integrated output to the comparator. COM2 and 3 respectively compare with the reference voltage from the stabilized power supply output terminal Vreg of the motor drive control circuit IC1 and input the respective comparison outputs to the exclusive OR circuit EXOR1 to generate the first pseudo pulse signal. It is a thing.

Further, the second pulse generating circuit 5 connects two integrating circuits 9 and 10 having different time constants to the input terminals of the start signal / stop signal, and integrates each when the stop signal (high level) is input. By making the rise of the output different and comparing the integrated output with the reference voltage from the stabilized power supply output terminal Vreg in the comparators COM4 and COM5, and inputting the respective comparison outputs to the exclusive OR circuit EXOR2, It generates two pseudo pulse signals.

The inverting circuit 6 is provided with an exclusive OR circuit EXOR3 to which the respective pseudo pulse signals from both pulse generation circuits 4 and 5 are input, and a collector and a base provided in the power supply circuits of the Hall elements H1 to H3. Two pairs of transistors Q6 to Q9 connected in common and an exclusive OR circuit E
And a transistor Q10 forming an inverter connected between the XOR3 and the bases of the transistors Q6 and Q7 of one set.

When the power is turned on, the first pulse generation circuit 4 outputs a high-level first pseudo pulse signal, and when the stop signal is input, the second pseudo-pulse generation circuit 5 outputs a high-level second pseudo pulse signal. In the inverting circuit 6, the pseudo pulse signals are inverted to the transistors Q6 and Q7 of one set and directly input to the transistors Q8 and Q9 of the other set, and the hall elements H1 to H1
The polarity of the power supply to 3 is inverted for the output time of this pseudo pulse signal.

That is, the power supply to the Hall elements H1 to H3 is normally supplied from the 12V power supply via the transistor Q8 and the transistor Q7. However, only when the pseudo pulse signal is input, the transistor Q6 and the transistor Q9 are supplied from the 12V power supply. Is supplied via the pulse signal and the detection signals from the Hall elements H1 to H3 are inverted by the time of the pseudo pulse signal.

Therefore, when the rotor is locked and the power is turned on to enter the start mode, the detection signals from the Hall elements H1 to H3 are generated by the first pseudo pulse signal from the first pulse generation circuit 4 only for the time of this pseudo pulse signal. Inverted,
Since it is possible to create a situation in which the rotor is rotating despite the rotor being locked, the starting current can be cut off.

When the stop signal is input when the rotor is locked, the second pulse from the second pulse generating circuit 5 is also output.
The detection signal from each Hall element H1 to H3 is inverted by the pseudo pulse signal for the time of this pseudo pulse signal, and it is possible to create a situation in which the rotor is rotated for a moment. Then, the rotation of the motor is detected by detecting the non-rotation of the rotor. Since it is detected that the speed has dropped below the specified value, it is possible to cut off the stop current.

In this case, when the stop signal is input during the rotation of the motor, the output signal from the Hall elements H1 to H3 may be mixed with the inversion signal by the second pseudo pulse signal to accelerate the rotation of the motor. . Therefore, in this embodiment, a third pulse generation circuit 11 is provided which generates a power-off signal having a pulse width longer than that of the second pseudo pulse signal when the stop signal is input.

That is, the third pulse generation circuit 11 includes a mono-multivibrator (hereinafter referred to as mono-multi) 12 activated by the rise of a stop signal, and an open collector type transistor into which a signal from the mono-multi vibrator 12 is input. Q11 and the collector of the transistor Q11 is connected to the frequency correction terminal FC of the motor drive control circuit IC1. The mono-multi 12 is set to output a signal having a pulse width longer than this signal at the rising edge of the second pseudo pulse signal.

Therefore, when the stop signal is input during the rotation of the motor, the Hall output is inverted by the time of the second pseudo pulse signal by the above-mentioned operation, but a signal of a time longer than that of the second pseudo pulse signal is generated by the monomulti 12. This signal is output, and the transistor Q11 is turned on by this signal and a low-level power-off signal is input to the correction terminal FC. Therefore, the power-off control stops current supply to the stator coils L1 to L3, and acceleration control is performed. Is avoided.

Although the embodiments of the motor drive control circuit protection device according to the present invention have been described above, the present invention is not limited to such embodiments, and various modifications can be made without departing from the scope of the present invention. It is possible.

[0044]

Since the present invention is constructed as described above, it has the following effects. In the motor drive control circuit protection device according to the first aspect of the present invention, when the rotation speed detection signal is not input within a predetermined delay time when the start signal is input, the power supply to the motor drive control circuit is turned off from the first protection circuit. Since the signal is input, even if the starting current flows when the rotor is locked, the supply of the starting current can be stopped by the power-off signal. Further, since the second protection circuit detects the stop of the motor by using the rotation speed detection signal from the motor drive control circuit and inputs the power off signal to the motor drive control circuit by this stop signal, the rotor is locked when the rotor is locked. Even if a stop signal is input,
It is possible to reliably stop the stop current supplied from the motor drive control circuit to the coil.

In particular, if the second protection circuit includes a start compensation circuit that cancels the stop signal when the start signal is input, the second protection circuit outputs the stop signal when the start signal is input when the motor is stopped. You can avoid problems.

In the motor drive control circuit protection device of the second invention, the first and second pseudo pulse signals are output from the first and second pulse generation circuits respectively when the power is turned on and the stop signal is input. Since the output signal of the sensor is inverted by the inversion circuit for the output time of this pseudo pulse signal, it is possible to create the same situation as if the motor was rotating for a moment, and even when the rotor is locked,
The starting current at the time of starting can be cut by this pseudo rotation, and the stopping current at the time of stop can be cut by detecting the decrease in the rotation speed due to the pseudo rotation.

In this case, if a third pulse generation circuit for generating a power-off signal having a pulse width longer than that of the second pseudo pulse signal when the stop signal is input is provided, the stop signal is input when the motor rotates and the pseudo pulse signal is generated. Even if the sensor signal is inverted and thereby the acceleration is attempted, the current supply to the coil can be stopped by the input of the power-off signal to the motor drive control circuit, and the acceleration control can be avoided.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a motor drive control circuit protection device according to the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the motor drive control circuit protection device according to the present invention.

FIG. 3 is a schematic configuration diagram of a motor drive control circuit showing a conventional example.

[Explanation of symbols]

 IC1 Motor drive control circuit H1 to H3 Hall element L1 to L3 Stator coil 1 First protection circuit 2 Second protection circuit 3 Startup compensation circuit 4 First pulse generation circuit 5 Second pulse generation circuit 6 Inversion circuit 11 Third pulse generation circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H02P 6/02 371 L

Claims (5)

[Claims] 1. A rotation control function for controlling an exciting current supplied to a coil based on an output signal of a sensor for detecting a rotation position of a motor, wherein a start mode and a stop mode are selected by a start signal and a stop signal, respectively. , A start signal is supplied to the coil by the start signal when the motor is stopped to perform acceleration control, the supply of the start current is stopped by detecting the rotation of the motor, and the rotation control function is executed. In a motor drive control circuit that supplies a stop current to the coil to perform brake control and stops the supply of the stop current when the motor speed drops below a specified value, a pulse signal with a frequency according to the motor speed. Rotation speed detection signal and the start signal are input, and when the start signal is input, a predetermined delay time A first protection circuit for inputting a power-off signal for stopping the current supply to the coil to the motor drive control circuit after the delay time when the rotation speed detection signal is not input to the rotation speed detection signal; A protection device for a motor drive control circuit, comprising: a second protection circuit for detecting a stop of the motor and inputting the power-off signal to the motor drive control circuit by the stop signal. 2. The motor drive control circuit protection device according to claim 1, wherein the second protection circuit includes a start compensation circuit that cancels the stop signal when the start signal is input. 3. A rotation control function for controlling an exciting current supplied to a coil based on an output signal of a sensor for detecting a rotation position of a motor, wherein the start mode and the stop mode are selected by a start signal and a stop signal, respectively. , Start signal is supplied to the coil by the start signal when the motor is stopped to perform acceleration control, the supply of the start current is stopped by detecting the rotation of the motor, and then the rotation control function is executed. Generates a first pseudo pulse signal when the power is turned on in the motor drive control circuit that supplies a stop current to the coil to control the brake and stops the supply of the stop current when the motor rotation speed falls below a specified value. And a second pulse generation circuit that generates a second pseudo pulse signal when the stop signal is input. And an inverting circuit that inverts the output signal of the sensor for the output time of each pseudo pulse signal by each pseudo pulse signal from the both pulse generation circuits, and the protection of the motor drive control circuit. apparatus. 4. The sensor comprises a Hall element, and the inverting circuit is configured to invert the polarity of the power source to the Hall element for the output time of each pseudo pulse signal by the input of each pseudo pulse signal. The motor drive control circuit protection device according to claim 3. 5. A third pulse generation circuit that generates a power-off signal having a pulse width longer than that of the second pseudo pulse signal when the stop signal is input is provided, and the power-off signal is input to the motor drive control circuit. The motor drive control circuit protection device according to claim 3, wherein the current supply to the coil is stopped by.