JP4984213B2 - DC motor drive device - Google Patents

Description

  The present invention relates to a DC motor driving apparatus having an overload protection function.

As shown in FIG. 8, Patent Document 1 includes an integration circuit AA having a time constant much larger than the DC motor start time, and even if a large current flows when the motor shaft is locked, There has been disclosed a direct current motor drive device that prevents the motor from generating heat and becoming hot by limiting the current to a small current within a time shorter than the time to generate heat and reach a high temperature state.
That is, when the voltage + V is applied and the start of the motor M is started, the value obtained by subtracting the base-emitter voltage of the transistor Q11 from the voltage of the Zener diode DZ by the action of the power control transistors Q11 and Q12 is the current detection resistor RD. When the motor current is equal to the terminal voltage of the motor and the motor is started at a constant speed, the torque command value voltage of the motor M becomes lower than the voltage of the Zener diode DZ. Since the integration circuit AA has a time constant much longer than the normal startup time, when the motor M is started in a locked state, the voltage at the point B gradually rises to a voltage at which the transistor Q10 is turned on. When reached, the base potential of the power control transistor Q11 is lowered so that only a small amount of current flows.

In Patent Document 2, as shown in FIG. 9, a motor drive signal OS is input to a signal input terminal I, a reset signal RS is input to a reset terminal R, and a motor control signal is output from a signal output terminal O. 110, a motor drive unit 120 that outputs a motor drive signal according to a control signal of the control unit 110, a DC motor M connected to an output terminal of the motor drive unit 120, and a current signal flowing through the DC motor M by voltage conversion. The signal conversion unit 130 that outputs the signal, the signal integration unit 140 that integrates and outputs the voltage when the overcurrent is detected by comparing the signal input from the signal conversion unit 130 with a certain reference voltage V1, and the signal integration unit 140 The DC motor driving device includes an overcurrent determination unit 150 that outputs a reset signal RS to the control unit 110 when an overcurrent is detected by comparing the output signal of the output signal with the reference voltage V2. There has been disclosed.
That is, the motor driving unit 120 includes a transistor Q20 and a relay RY, the relay RY includes an electromagnet EM and a switch S, the signal converting unit 130 includes a resistor R1, and the signal integrating unit 140 includes an input resistor R2 and a first operational amplifier OP4. And capacitor C. The overcurrent determination unit 150 includes a second operational amplifier OP5 in which the output voltage of the first operational amplifier OP4 is input to the inverting input terminal and the second comparison reference voltage V2 is input to the non-inverting input terminal. When the drive signal OS is input to the signal input terminal I of the control unit 110, a signal is output from the control unit 110 to the motor drive unit 120, the relay RY is turned on, and the switch S is closed. When the current IM flows through the DC motor M, the motor voltage V0 is supplied to the inverting input terminal of the first operational amplifier OP4 through the input resistor R2. The signal integrator 140 compares and integrates the motor voltage supplied to the inverting input terminal of the first operational amplifier OP4 with the first comparison reference voltage V1 of the non-inverting input terminal, and outputs an integrated voltage V3. The integrated voltage V3 is supplied to the inverting input terminal of the second operational amplifier OP5 of the overcurrent determining unit 150. The overcurrent determining unit 150 compares the integrated voltage V3 with the second comparison reference voltage V2, and the integrated voltage V3 is compared with the second comparison. When the voltage is smaller than the reference voltage V2, the reset signal RS is output to the control unit 110. The control unit 110 outputs a signal for turning off the DC motor M by the reset signal RS. When the direct current motor M is initially operated, an overcurrent is instantaneously generated. However, since the integrated voltage V3 is larger than the second comparison reference voltage V2, it is determined that the current amount is not sufficient to damage the direct current motor M. Does not output RS.

In Patent Document 3, as shown in FIG. 10, an overcurrent detection signal is generated when a control means for rotating and stopping a motor by an external rotation control signal and a load current of the motor exceeds a set current value. An overcurrent detection means, a time management means for managing the output time of the overcurrent detection signal, and a storage means for storing the output signal of the time management means are provided, the output of the storage means is fed back to the control means and the motor is stopped. In the motor control apparatus as described above, there is described a device provided with clear means for clearing the storage means while the rotation control signal instructs the rotation stop of the motor.
That is, since the control for instructing the rotation and stop of the DC motor M by the rotation control signal 210 of the main controller 230 executes general PWM drive control, the rotation detector 221 detects the speed in response to the rotation of the DC motor M. Outputs a pulse signal. The speed comparator 201 compares the speed detection pulse signal with the reference clock pulse signal 228 of the main controller 230 and outputs the difference as a speed difference signal. The waveform generator 203 outputs a reference waveform signal for PWM drive control, and the comparator 202 compares the speed difference signal with the reference waveform signal and outputs a drive pulse signal. The driver 204 turns on and off the drive current of the DC motor M in response to the drive pulse signal, and rotates the DC motor M at a predetermined speed. The speed comparator 201 puts the DC motor M into the rotation control state and the stop control state by the rotation control signal 210. The load current of the DC motor M flows to the ground through the current detection resistor R6, and the overcurrent detection circuit 207 detects the load current flowing to the DC motor M based on the terminal voltage of the current detection resistor R6, and the value is excessive. When the current judgment reference value is exceeded, the overcurrent detection signal 216 is set to the high level. The timer circuit 208 operates when the overcurrent detection signal 216 becomes high level, and sets the overload detection signal 217 to low level when the high level state continues for a predetermined time t or longer. When the overload detection signal 217 becomes low level, the storage circuit 209 sets the protection output signal 218 to high level and stores the state. The inverting circuit 223 inverts the protection output signal 218 to convert it to a low level, stops driving the driver 204, and stops the rotation of the DC motor 5. The set time t of the timer circuit 208 is set longer than the overcurrent continuation time when the DC motor M is started, and the overload detection signal 217 is not output with the overcurrent detection signal 216 that is less than or equal to the set time t. A clear signal 220 obtained by inverting the signal level of the rotation control signal 210 by the inverting circuit 224 is applied to the input terminal CLR that clears the storage state of the storage circuit 209. Since the clear signal is input to the input terminal CLR of the storage circuit 209 while the rotation control signal 210 is at a high level, which means that the rotation of the motor is stopped, even if there is an external noise or an instantaneous power interruption during this period When the circuit 209 does not operate and the rotation control signal 210 of the main control circuit 230 becomes a low level that means the rotation of the motor, the DC motor M can be rotated.
JP-A-6-205595 Japanese Patent Laid-Open No. 9-23673 JP-A-6-105453

  In the drive device of Patent Document 1, even if a large current flows when the motor shaft is locked, the motor is heated to a high temperature by limiting the current to a small current within a shorter time than the time when the motor generates heat and reaches a high temperature state. However, since the limit value of the current flowing through the motor is determined only by the time constant of the CR circuit until the base emitter voltage of the transistor Q11 is reached, the variation of the transistor Q10, the resistors RD, R, and the capacitor C is caused. It is difficult to adjust the current limit value, and since the capacitor C is always charged, even if a current exceeding the rated current is temporarily passed to increase the torque, the protection circuit works and it is difficult to increase the torque. There's a problem. Also, if the limit value is set to a current value that slightly exceeds the rated current, the protection circuit may not work even if an overload condition that slightly exceeds the rated current continues, and a timer element is included, so the motor There is a problem that the control element cannot be protected when the current increases instantaneously, such as a short circuit.

  Further, in the driving device of Patent Document 2, when an overcurrent flows through the DC motor M for a predetermined time, the integrated voltage V3 becomes smaller than the second comparison reference voltage V2, and the reset signal RS is output to the control unit 110. Therefore, even if an overcurrent momentarily flows through the DC motor M during the initial operation, the rotation can be continued without outputting the reset signal RS. Since the capacitor C is always charged, even if a current exceeding the rated current is temporarily passed in order to increase the torque, the protection circuit works in a short time, and the relay RY is turned off for a predetermined time and becomes in an intermittent operation state. There is. Also, if the limit value is set to a current value that slightly exceeds the rated current, the protection circuit may not work even if an overload condition that slightly exceeds the rated current continues, and a timer element is included, so the motor There is a problem that the control element cannot be protected when the current increases instantaneously, such as a short circuit.

Further, in the drive device of Patent Document 3, the protection circuit is configured to operate when the motor overcurrent state continues for a certain period of time. However, the rotation control signal 210 ( It is necessary to output a clear signal 220), and there is a problem that the apparatus becomes large. Further, since the timer element is included, there is a problem that the control element cannot be protected when the current increases instantaneously such as a short circuit of the motor.
The problem of the present invention is that the control circuit of the DC motor can be surely protected and self-recovered when a large current flows through the DC motor, and can be integrated into a small electronic circuit board. An object of the present invention is to provide a DC motor driving apparatus having a configuration.

In a DC motor drive device equipped with a protection function for a DC motor control circuit when a large current flows, current detection means for detecting the current flowing through the DC motor and input proportional to the current detected by the current detection means CR integration circuit that performs CR integration and outputs the CR integration value, and determines whether or not the current detected by the current detection means is less than the rated current. When the current is larger than the rated current, the CR integration circuit is activated to be proportional to the current value. The overload is determined by charging the capacitor of the CR integration circuit and discharging the capacitor to reset the CR integration circuit so that it does not work when the current is below the rated current. determines greater or not than the set value, the overload determining means for blocking the output to the DC motor when the output of the CR integrator is larger than the overload setting value, the Force is determined whether only the blocking means for blocking the output to the DC motor when larger than the overload setting value, the stop time set value downtime and then cut the output of the DC motor is set in advance while Ru and a stop end determination means for returning current output to the DC motor when passed, the current the current detection unit detects that determines whether larger or not than a short circuit setting value set in advance, the Short-circuit determining means for operating a quick charging means for charging a capacitor of the CR integration circuit with a voltage proportional to the current;
In the overload protection operation when the DC motor is overloaded, when the overload is judged (S13), the shut-off means is operated to shut off the output to the DC motor and stop the rotation (S14). The overload determination of the output of the integration circuit is switched to the stop end determination by the stop end determination means (S15), and the CR integration circuit starts discharging the capacitor by stopping the current detection (S16). The rotation stop of the DC motor is determined (S17). When the DC motor is discharging, the stop time determination unit determines the stop time of the DC motor (S18), and the stop time exceeds the stop time set value. When the stop end determination means releases the blocking means via the overload determination means and restarts the rotational drive of the DC motor (S19), when the discharge is not being performed and when the stop end determination means ends the stop When it is not determined, while operating terminated without outputting the cancel signal to the blocking means,
In the short-circuit protection operation when the DC motor is short-circuited, when the short circuit determination is made (S2), the CR integrated value is output to the overload determination unit via the quick charging unit, and the overload determination unit performs overload determination. (S4), and then repeating a series of overload determination operation and short-circuit determination operation for performing the same operation as the overload protection operation and terminating the operation,
The stop termination determination means is executed in each of the overload protection operation and the short circuit protection operation, and the DC motor is protected by temporarily stopping energization of the DC motor in the event of a short circuit and overload. When the stop time set value has elapsed, the direct current motor is resumed and the direct current motor is self-returned (claim 1).

Also, the present invention provides blocking of the direct current motor so as to drive by using the bridge switch elements P WM drive control, cuts off said shorting judging means, the output of the overload determination means to the DC motor A signal is sent to actuate the shut-off means, and the shut-off means sends a shut-off command to turn off the bridge switch element (S3, S5, S14), stopping the rotation drive of the DC motor, while stopping the stop The judging means outputs a release signal to the shut-off means via the overload judging means, and the bridge switch element is turned on (S11, S20) to resume the rotational drive of the DC motor (Claim 2 ). .
In the present invention, an overload set value and a stop time set value are set so that an average current greater than or equal to the rated current does not flow to the DC motor in the event of an overload, and the average current value is calculated as follows: average current value = (load It is calculated by (current peak value * energization time) / (energization time + pause time), and the pause time is a discharge time of the capacitor of the CR integration circuit (claim 3 ).
Further, according to the present invention, the short-circuit judging means turns off the shut-off means bridge switch element (S3) when the current is larger than the short-circuit set value, and immediately shuts off the output to the DC motor and short-circuits. The bridge switch element for PWM drive control is characterized by not allowing a current exceeding the rated current to flow (claim 4 ).

  In the present invention, when the current of the DC motor detected by the current detection means is larger than the rated current, the overload constant determination means operates the CR integration circuit, and the CR integration circuit sets a value proportional to the current from the current detection means to CR integration. When the output of the CR integration circuit becomes larger than the overload setting value, the overload determination means shuts off the output to the DC motor, and when the current of the DC motor is less than the rated current, the overload constant determination means Since the integration circuit is reset so that it does not work, when the DC motor is operating near the rated current, even if the rated current is slightly exceeded due to a slight influence of the load, it will be judged as an overload. The DC motor can be operated smoothly. Also, the CR integration circuit performs CR integration on a value proportional to the current from the overload constant determination means, and when the output of the CR integration circuit becomes larger than the overload set value, the overload determination means outputs the output to the DC motor. When the stop time after the shut-off has exceeded the preset stop time set value, the stop end judgment means restores the output to the DC motor, and temporarily turns on the DC motor in the event of an overload. Since the DC motor is protected by stopping it, it is possible to provide a stop period for energization of the DC motor in the event of an overload, and the average current value of the DC motor can be reduced below the rated current. Can be reliably protected. Also, when the output of the CR integration circuit becomes larger than the overload set value, the overload determination means shuts off the output to the DC motor, and the pause time from the cutoff exceeds the preset stop time set value In addition, the stop end determination means restores the output to the DC motor, so it can self-recover without the need for an expensive and bulky arithmetic unit such as a CPU, and it is an inexpensive, small component such as an amplifier, comparator, or transistor. In addition, the entire structure can be made simple, simple, inexpensive, small, and fit in a small space.

Further, in the present invention, when the current detected by the current detecting means is larger than a preset short-circuit setting value, the short-circuit judging means cuts off the output to the DC motor and activates the CR integration circuit. Since the DC motor is protected by temporarily stopping the energization of the DC motor, it is possible to provide an energization stop period for the DC motor even in the event of a short circuit, and a current exceeding the rated current can be provided to the DC motor. The flow can be prevented and self-recovery can be performed, and the control circuit of the DC motor can be reliably protected.
Also, in the present invention, the DC motor is driven using a bridge switch element for PMW drive control, so that the DC motor drive device has a simple configuration (simple), is inexpensive and small, and is PWM controlled. Along with the bridge element that performs the above, it can be collected on a small substrate.
Further, in the present invention, in order to prevent the average current exceeding the rated current from flowing to the DC motor in the event of an overload , in detail, an overload set value and a stop time set value are set, and the average current value = (load current peak value) * Energization time) / (Energization time + pause time) The average current value calculated by (current supply time + rest time) should not be exceeded, or the short circuit determination means may be configured to turn off the interruption means bridge switch element when the current is greater than the short circuit setting value. Since it is turned off (S3), the output to the DC motor is cut off immediately, so that no current exceeding the rated current flows through the bridge switch element for PMW drive control in the event of a short circuit. There is an advantage of ensuring protection.

    FIG. 1 is a block diagram of a DC motor driving apparatus showing an embodiment of the present invention, FIG. 2 is an operation explanatory diagram when a DC motor is short-circuited, and FIG. 3 is an operation explanatory diagram when a DC motor is overloaded. The DC motor drive device controls the rotation and stop of the DC motor M via the bridge switch element 2 by forward and reverse pulse signals from the external control device 1. The control device 1 executes general PWM (pulse width modulation) drive control. The current detection means 3 detects a current flowing through the DC motor M via the bridge switch element 2, converts the current into a voltage, and the amplifier 4 amplifies the voltage. The overload constant determination means 5 determines whether or not the current flowing through the DC motor M is less than or equal to the rated current value based on the amplified voltage value. When the current is larger than the rated current, the CR integration circuit 6 shown below is operated to The CR integration circuit 6 is reset so that the CR integration circuit 6 does not work when the value is less than the value. The CR integration circuit 6 performs CR integration on the voltage in response to the input of an amplified voltage proportional to the current detected by the current detection means 3, and outputs a CR integration value. Further, the CR integration circuit 6 operates when the current of the DC motor M is larger than the rated current value by the operation of the overload always-on determination means 5 except when the short circuit occurs, and the current of the DC motor M exceeds the rated current value. Since it does not operate in a small normal operating state, the life can be extended.

  The short circuit determination means 7 determines whether or not the current of the DC motor M detected by the current detection means 3 is larger than a preset short circuit setting value, and shuts off the output to the DC motor M when it is larger than the short circuit setting value. The shut-off means 8 is operated so that the shut-off means 8 sends a shut-off command to the bridge switch element 2 and shuts off the output to the DC motor M (stops rotation of the DC motor M). The short-circuit determining means 7 operates the quick charging means 9 when the current of the DC motor M detected by the current detecting means 3 is larger than the short-circuit set value, and the voltage proportional to the current detected by the current detecting means 3 is CR. The CR integration circuit 6 inputs to the integration circuit 6, and CR input is proportional to the current flowing through the DC motor M when a short circuit occurs, and a CR integration value is output. The overload determination means 10 determines whether or not the output of the CR integration circuit 6 is larger than a preset overload set value. When the output of the CR integration circuit 6 becomes larger than the overload set value, the DC motor M The shut-off signal is transmitted to the shut-off means 8 for shutting off the output to the switch, and the shut-off means 8 is operated. The shut-off means 8 sends a shut-off command to the bridge switch element 2 and shuts off the output to the DC motor M (DC motor M Stop rotating). The stop end determination means 12 is a stop time setting value (stop level setting value) preset by a pause time (stop time) after the short circuit determination means 7 and the overload determination means 10 shut off the output to the DC motor M. When the stop time exceeds the stop time set value (including when the time has elapsed), a release signal is output to the shut-off means 8 via the overload judgment means 10 and the shut-off is performed. The means 8 sends a return command for returning the output to the DC motor to the bridge switch element 2 to restart the output to the DC motor M (rotation drive of the DC motor M). That is, even when the energization to the DC motor M is cut off during a short circuit or overload, the energization to the DC motor M is resumed when the stop time set value elapses, and the DC motor M returns itself. ing.

In the drive device having the above-described configuration, when the DC motor M is energized to start the DC motor M, the current detection means 3 detects the current flowing through the DC motor M and converts the current into voltage, and the voltage is amplified by the amplifier. 4 is amplified and input to the overload constant determination means 5. The overload constant determination means 5 determines whether or not the average current value flowing through the DC motor M is less than or equal to the rated current value based on the input. When the average current value is larger than the rated current, the CR integration circuit 6 is activated to charge the capacitor C. The CR integration circuit 6 outputs the CR integration value to detect overload, but when the current is below the rated current value, the capacitor C is discharged so that the CR integration circuit 6 does not work, and the CR integration circuit 6 is reset. To do.
Next, a short-circuit protection operation flow when the DC motor M is short-circuited will be described with reference to FIG. When the start of the short circuit determination starts in step S1 by starting the direct current motor M, the short circuit determination means 7 determines whether or not the current of the direct current motor M is larger than the short circuit set value in step S2. If it is determined to be greater than the preset short-circuit set value, “Yes”, the shut-off means 8 sends a shut-off command to the bridge switch element 2 in S3 to turn off the bridge switch element 2 and output to the DC motor M. The motor is shut off to stop the rotation of the DC motor M, and the voltage proportional to the current of the DC motor M is input to the CR integration circuit 6 via the quick charging means 9 in S4 to charge the capacitor C of the CR integration circuit 6. Then, the CR integration circuit 6 performs CR integration on an input proportional to the current flowing through the DC motor M and outputs a CR integration value. Then, when the overload determination means 10 performs a determination operation that the output (CR integral value) of the CR integration circuit 6 is larger than a preset overload set value, the cutoff means 8 sends a cutoff command to the bridge switch element 2 in S5. , And the bridge switch element 2 is turned off, the output to the DC motor M is shut off and the rotation of the DC motor M is stopped. However, since the rotation of the DC motor M is usually already stopped, it is safe. Will be reconfirmed for. When the overload determination unit 10 determines that the output of the CR integration circuit 6 is overloaded, the CR integration circuit output determination is changed from the overload determination by the overload determination unit 10 to the stop end determination by the stop end determination unit 12 in S6. Switched.

  Thereafter, in step S7, the output to the DC motor M is interrupted in S3 and S5, and the current of the DC motor M becomes zero. As a result, the current of the DC motor M detected by the current detection means 3 becomes zero and the current The detection is turned off, and the CR integration circuit 6 starts discharging the amount of power charged in the capacitor C. Next, in step S8, it is determined whether or not the output to the DC motor M is being cut off, that is, whether or not the capacitor C is being discharged, and is being discharged, that is, the rotation stop of the DC motor M is being continued. If “Yes” is determined, the stop end determination means 12 passes the stop time set value (stop level set value) preset by the stop time (discharge time of the capacitor C) T of the DC motor M in step S9. In the case of “Yes” when the stop time setting value is passed and the stop end is determined to be “Yes”, the stop end determination means 12 sends a release signal to the shutoff means 8 via the overload determination means 10 in step S10. Output, the bridge switch element 2 is turned ON, the rotational drive of the DC motor M is restarted, and the self-reset is performed. In step S2, when the short-circuit determining means 7 determines that the current of the DC motor M is equal to or less than the short-circuit set value, it outputs a release signal to the shut-off means 8 because it is not short-circuited. Without proceeding to step S8, it is determined in step S8 whether the output to the DC motor M is being cut off, that is, whether the capacitor C is being discharged. Further, when “NO” is determined in step S8 that the capacitor C is not being discharged, or when “NO” is determined in step S9 that the stop / end determination unit 12 does not determine stop / end, respectively, the blocking unit. S11 is terminated without outputting the release signal to 8, and the series of short-circuit determination operations described above are repeated.

  Next, the flow of the overload protection operation when the DC motor M is overloaded will be described with reference to FIG. When the overload determination start is started in step S12 by starting the DC motor M, the overload determination means 10 performs an overload determination operation that the output of the CR integration circuit 6 is larger than the overload set value in S13. In this case, in step S14, a cutoff signal is transmitted to the cutoff means 8, and the cutoff means 8 sends a cutoff command to the bridge switch element 2 to turn off the bridge switch element 2 and cut off the output to the DC motor M. Then, the rotation of the DC motor M is stopped. When the overload determination means 10 determines that the output of the CR integration circuit 6 is overloaded as described above, the CR integration circuit output determination is changed from the overload determination by the overload determination means 10 to the stop end determination means 12 in S15. It is switched to stop end determination.

  Thereafter, in step S16, the rotation of the DC motor M is stopped and the current of the DC motor M becomes zero. As a result, the current of the DC motor M detected by the current detection means 3 becomes zero and the current detection is turned OFF. Thus, the CR integration circuit 6 starts discharging the amount of power charged in the capacitor C. Next, in step S17, it is determined whether or not the output to the DC motor M is being cut off, that is, whether or not the capacitor C is being discharged. The stop end determination means 12 determines whether or not the stop time of the DC motor M (the discharge time of the capacitor C) has exceeded a preset stop time set value (stop level set value), and stops after the stop time set value. When the determination is “Yes”, the stop / end determination means 12 outputs a release signal to the shut-off means 8 via the overload determination means 10 in step S19, and the bridge switch element 2 is turned on to activate the DC motor. The rotational drive of M is restarted and self-resets. If the overload determination means 10 determines in step S13 that the current of the DC motor M is equal to or less than the overload set value, it is not an overload condition, so a cutoff signal is sent to the cutoff means 8. The process proceeds to step S17 without outputting, and it is determined whether or not the output to the DC motor M is cut off, that is, whether or not the capacitor C is discharged. Further, when “NO” is determined in step S17 that the capacitor C is not being discharged, or when “NO” in step S18, the stop / end determination unit 12 does not determine stop / stop, respectively, the blocking unit. S20 is terminated without outputting a release signal to 8, and the series of overload determination operations described above are repeated.

  Next, FIG. 4 is a graph showing the relationship between the current value and time of the DC motor M when the DC motor M is short-circuited, and the relationship between the CR integration output (CR integration value) of the CR integration circuit 6 and time. When a short circuit occurs, a current larger than the short circuit set value flows. However, when the short circuit determination unit 7 determines that the detected current value of the current detection unit 3 is greater than the short circuit set value, the energization to the DC motor M is instantaneously stopped. Therefore, a current slightly larger than the short-circuit set value flows to the DC motor M only instantaneously, as indicated by the symbol a. Also, a large voltage proportional to a large current value at the time of a short circuit is input to the CR integrating circuit 6 and rapidly charged into the capacitor C, and the CR integrated output of the CR integrating circuit 6 is instantaneously set to the overload setting value as indicated by symbol B. If the current exceeds the value, the energization to the DC motor M is immediately stopped (in the case shown in the figure, the energization to the DC motor M has already been stopped by the short-circuit determining means 7, so a safety reconfirmation is required, but this may be omitted). Is possible). When the energization of the DC motor M is stopped, the current value of the DC motor M becomes zero, and the amount of power charged in the capacitor C of the CR integration circuit 6 is gradually discharged. When this discharge time, that is, the pause time of the DC motor M becomes a preset stop time set value and the CR integrated output becomes the pause release value, the stop end determination means 12 sends a release signal to the cutoff means 8 to send the DC motor M. To self-reset. At that time, if the DC motor M is still in a short circuit state, the above operation is repeated, and a state in which a large current flows instantaneously for a very short time every predetermined time is repeated. Even if the DC motor M is short-circuited, the DC motor M is intermittently suspended by passing a current through the DC motor M only for a very short period of time as described above. 2 can be reliably protected.

  FIG. 5 is a graph showing the relationship between the current value and time of the DC motor M when the DC motor M is overloaded, and the relationship between the CR integration output (CR integration value) of the CR integration circuit 6 and time. In the case of an overload in which a current that is larger than the overload set value and smaller than the short-circuit set value flows continuously to the DC motor M as indicated by the symbol C, a voltage proportional to the overload current value is a CR integration circuit 6. When the CR integration output of the CR integration circuit 6 exceeds the overload set value, the overload determination means 10 determines overload. Then, a cutoff signal is transmitted to the cutoff means 8 to stop energization of the DC motor M. By stopping energization of the DC motor M, the current value of the DC motor M becomes zero, and the amount of power charged in the capacitor C of the CR integration circuit 6 is gradually discharged. When this discharge time, that is, the pause time of the DC motor M becomes a preset stop time set value and the CR integrated output becomes the pause release value, the stop end determination means 12 sends a release signal to the cutoff means 8 to send the DC motor M. Is driven to rotate. At that time, if the DC motor M is still in an overload state, the above operation is repeated, and the state in which the overload current flows for a short time every predetermined time is repeated. Even if the DC motor M is in an overload state, as described above, the DC motor M is intermittently stopped while the overload current flows through the DC motor M only for a short period every stop time. And the bridge switch element 2 can be reliably protected.

  FIG. 6 is a graph showing the relationship between the current value and time of the DC motor M when the DC motor M is in different overload states, and the relationship between the CR integration output (CR integration value) of the CR integration circuit 6 and time. . In the case of an overload in which a current value that is slightly larger than the overload set value and smaller than the short circuit set value flows continuously as indicated by the symbol E in the DC motor M, a voltage proportional to the overload current value is CR. When input to the integration circuit 6, the capacitor C is gradually charged over a relatively long energization time as indicated by reference numeral, and the CR integration output of the CR integration circuit 6 exceeds the overload set value, the overload determination means 10 is cut off. An interruption signal is transmitted to the means 8 to stop energization of the DC motor M. By stopping energization of the DC motor M, the current value of the DC motor M becomes zero, and the amount of power charged in the capacitor C of the CR integration circuit 6 is gradually discharged. When this discharge time, that is, the pause time of the DC motor M becomes a preset stop time set value and the CR integrated output becomes the pause release value, the stop end determination means 12 sends a release signal to the cutoff means 8 to send the DC motor M. Is driven to rotate. At that time, when the DC motor M is still in the same overload state, the above operation is repeated, and the state where the overload current flows for a relatively long time every predetermined time is repeated. Even if the DC motor M is in an overload state, as described above, the DC motor M is intermittently suspended from energizing the DC motor M because an overload current flows through the DC motor M for each predetermined period of time. And the bridge switch element 2 can be reliably protected.

  FIG. 7 shows that when an overload current flows intermittently through the DC motor M as shown in FIGS. 5 and 6, the average current value flowing through the DC motor M is lower than the rated current value of the DC motor M. This indicates that an overload set value or a rest time set value has been set. The average current value is calculated by the following formula. Average current value = (load current peak value * energization time) / (energization time + outage time). Therefore, in the event of an overload, the average current exceeding the rated current will not flow to the DC motor, and in the event of a short circuit, the current exceeding the rated current will not flow to the bridge switch element. The average current value can be reduced below the rated current, and the DC motor control circuit can be reliably protected.

It is a block diagram which shows the drive device of the DC motor of this invention. It is operation | movement explanatory drawing at the time of a DC motor short circuit. It is operation | movement explanatory drawing at the time of a DC motor overload. It is a time chart which shows the electric current value at the time of a short circuit, and CR integral output. It is a time chart which shows the electric current value at the time of an overload, and CR integral output. It is a time chart which shows the electric current value at the time of different overload, and CR integral output. It is a time chart which shows the average electric current value at the time of an overload. It is an electric circuit diagram which shows the drive device of the DC motor of conventional patent document 1. It is an electric circuit diagram which shows the drive device of the DC motor of the conventional patent document 2. It is a block diagram which shows the drive device of the direct current motor of conventional patent document 3.

Explanation of symbols

M DC motor
T DC motor downtime
2 Bridge switch element 3 Current detection means 5 Overload constant judgment means 6 CR integration circuit 7 Short circuit judgment means
8 Blocking means
9 Quick charging means 10 Overload judging means 12 Stop end judging means

Claims (4)

In a DC motor drive device equipped with a protection function for a DC motor control circuit when a large current flows, current detection means for detecting the current flowing through the DC motor and input proportional to the current detected by the current detection means CR integration circuit that performs CR integration and outputs the CR integration value, and determines whether or not the current detected by the current detection means is less than the rated current. When the current is larger than the rated current, the CR integration circuit is activated to be proportional to the current value. The overload is determined by charging the capacitor of the CR integration circuit and discharging the capacitor to reset the CR integration circuit so that it does not work when the current is below the rated current. determines greater or not than the set value, the overload determining means for blocking the output to the DC motor when the output of the CR integrator is larger than the overload setting value, the Force is determined whether only the blocking means for blocking the output to the DC motor when larger than the overload setting value, the stop time set value downtime and then cut the output of the DC motor is set in advance while Ru and a stop end determination means for returning current output to the DC motor when passed, the current the current detection unit detects that determines whether larger or not than a short circuit setting value set in advance, the Short-circuit determining means for operating a quick charging means for charging a capacitor of the CR integration circuit with a voltage proportional to the current;
In the overload protection operation when the DC motor is overloaded, when the overload is judged (S13), the shut-off means is operated to shut off the output to the DC motor and stop the rotation (S14). The overload determination of the output of the integration circuit is switched to the stop end determination by the stop end determination means (S15), and the CR integration circuit starts discharging the capacitor by stopping the current detection (S16). The rotation stop of the DC motor is determined (S17). When the DC motor is discharging, the stop time determination unit determines the stop time of the DC motor (S18), and the stop time exceeds the stop time set value. When the stop end determination means releases the blocking means via the overload determination means and restarts the rotational drive of the DC motor (S19), when the discharge is not being performed and when the stop end determination means ends the stop When it is not determined, while operating terminated without outputting the cancel signal to the blocking means,
In the short-circuit protection operation when the DC motor is short-circuited, when the short circuit determination is made (S2), the CR integrated value is output to the overload determination unit via the quick charging unit, and the overload determination unit performs overload determination. (S4), and then repeating a series of overload determination operation and short-circuit determination operation for performing the same operation as the overload protection operation and terminating the operation,
The stop termination determination means is executed in each of the overload protection operation and the short circuit protection operation, and the DC motor is protected by temporarily stopping energization of the DC motor in the event of a short circuit and overload. A driving apparatus for a direct current motor in which energization to the direct current motor is resumed when the stop time set value has elapsed and the direct current motor is automatically restored . The DC motor is driven using a bridge switch element for PWM drive control, and the short-circuit determination means and the overload determination means transmit a cutoff signal that cuts off the output to the DC motor, and the cutoff The shut-off means transmits a shut-off command and the bridge switch element is turned off (S5, S14) to stop the rotation drive of the DC motor, while the stop end judging means is passed through the overload judging means. outputs a release signal to the shutoff unit Te, oN operating the bridge switch elements (S11, S20) is allowed to drive the DC motor of claim 1 Symbol mounting, characterized in that to resume the rotation of the DC motor. Set the overload setting value and stop time setting value so that the average current exceeding the rated current does not flow to the DC motor during overload , and the average current value is: average current value = (load current peak value * energization time 3. The DC motor driving apparatus according to claim 1, wherein the driving time is calculated by: / (energizing time + resting time), and the resting time is a discharging time of a capacitor of the CR integration circuit . The short-circuit judging means turns off the shut-off means bridge switch element when the current is larger than a short-circuit set value (S3), immediately shuts off the output to the DC motor, and performs the PWM drive control in the event of a short-circuit. 3. The DC motor driving apparatus according to claim 2 , wherein a current exceeding a rated current is not supplied to the bridge switch element.

Images