JP2007074791A - Driving unit for motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving unit for a motor, which can inform the user of its abnormal state continuously when the motor stops due to occurrence of abnormality. <P>SOLUTION: This drive unit is equipped with an inverter circuit 14, an abnormality detecting circuit 18, a control circuit 16, and a hold circuit 20 where a D (Delay) flip-flop and an RS (Reset Set) flip-flop are united so as to hold an LED (Light Emitting Diode) 28 until it is reset after the pulsated detection signal from the abnormality detecting circuit 18 is inputted. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drive device such as a brushless DC motor, and more particularly to a device that operates when an abnormality is detected.

  Conventionally, there has been proposed a drive device that detects an overload state of a brushless DC motor (hereinafter simply referred to as a motor) or detects an overcurrent to stop the motor (see, for example, Patent Document 1).

Such a motor drive device is automatically controlled by a microcomputer, and constantly monitors the power supply voltage and drive current for the motor, detects an abnormality, stops the drive signal, and immediately resets to the initial state. The program is embedded.
JP 2003-220576 A

  However, in the motor driving apparatus as described above, since an abnormality is detected and reset as soon as the motor stops, a detection signal indicating an abnormal state is in an initial state. For example, even when a notification system such as an LED is provided, since this detection signal disappears in an instant, there is a problem that it is impossible to recognize the cause of the stop afterward.

  Therefore, in view of the above problems, the present invention provides a motor drive device capable of continuously reporting an abnormal state when the motor is abnormal and stopped.

  The invention according to claim 1 is an inverter circuit that supplies a drive current to a motor, an abnormality detection circuit that detects an abnormal state of the motor and outputs a pulsed detection signal, and controls the inverter circuit, And a control circuit that stops or decelerates the rotation of the motor when a detection signal is input, and an abnormality detection signal holding unit that continuously notifies an abnormal state when the detection signal is input; And a reset unit that resets the notification state in the abnormality detection signal hold unit.

  According to a second aspect of the present invention, the abnormality detection signal holding means is a D-type flip-flop circuit, the detection signal is input to a clock pulse input terminal of the D-type flip-flop circuit, and an abnormality is notified to an output terminal Q. The motor driving device according to claim 1, wherein an electronic element to be performed is connected.

  According to a third aspect of the present invention, the reset means is an RS flip-flop circuit, a selection switch is connected to the input terminal R of the RS flip-flop circuit, and an electronic element that reports an abnormality is connected to the output terminal Q. 2. The motor driving apparatus according to claim 1, wherein a DC power source is connected to one selection terminal of the selection switch, and the other selection terminal is grounded.

  According to a fourth aspect of the present invention, the abnormality detection signal holding means and the reset means are D-type and RS-type integrated flip-flop circuits, and the detection signal is input to a clock pulse input terminal of the integrated flip-flop circuit. The output terminal Q is connected to an electronic element for notifying abnormality, the input selection terminal R is connected to a selection switch for resetting, a DC power source is connected to one selection terminal of the selection switch for resetting, and the other selection terminal is 2. The motor driving device according to claim 1, wherein the motor driving device is grounded.

  The invention according to claim 5 is the motor driving apparatus according to claim 1, wherein the electronic element is an LED.

  The invention according to claim 6 is the motor drive device according to claim 1, wherein the motor is a brushless DC motor.

  In the motor driving apparatus of the present invention, when a detection signal is input to the abnormality detection signal holding means, the abnormality state is continuously notified, and when the operator recognizes the abnormality detection, the reset means is used for resetting. Thus, the abnormal state can be notified until the worker resets, and it is possible for the worker to determine that an abnormality has occurred in the motor.

  Hereinafter, a motor drive device 10 according to an embodiment of the present invention will be described with reference to FIGS.

  The driving device 10 is a driving device for a brushless DC motor (hereinafter simply referred to as a motor) 12, and includes an inverter circuit 14, a control circuit 16 that controls the inverter circuit 14, and an abnormality detection that detects rotation abnormality of the motor 12. The circuit 18 and an abnormality detection signal hold circuit (hereinafter simply referred to as a hold circuit) 20 are configured.

  The inverter circuit 14 performs PWM control by the control circuit 16 and outputs three-phase drive currents to the three-phase stator windings of the motor 12, respectively. The inverter circuit 14 is configured by a full bridge circuit including six FETs.

  The control circuit 16 composed of a microcomputer performs feedback control based on a speed command signal from the outside and rotation signals from three hall ICs (not shown) provided in the motor 12, and a rotation speed corresponding to the speed command signal. The PWM signal is output to the inverter circuit 14 so that In addition, the control circuit 16 stops the rotation of the motor 12 when a pulse-shaped detection signal from the abnormality detection circuit 18 is input. In this case, the speed may be reduced.

  The abnormality detection circuit 18 detects the drive current supplied from the inverter circuit 14 to the three-phase stator winding of the motor 12, and determines that the drive current is overloaded when the drive current exceeds a threshold value. Outputs a pulsed detection signal.

  The hold circuit 20 is composed of an integrated flip-flop circuit in which a D-type flip-flop circuit and an RS-type flip-flop circuit are integrated. A pulse-like detection signal from the abnormality detection circuit 18 is input to the clock pulse input terminal of the hold circuit 20. Further, a DC voltage Vcc is applied to the input terminal D. The input terminal S is grounded. The input terminal R is connected to a selection switch 22 having two input terminals. The first selection terminal of the selection switch 22 is applied with the DC power source Vcc, and the second selection terminal 26 is grounded.

  The DC power supply Vcc also serves as a drive power supply for driving the hold circuit 20. Further, a light emitting diode (hereinafter referred to as LED) 28 is connected to the output terminal Q through a resistor R, and the output side of the LED 28 is grounded.

(2) Operating state of drive device 10 In a normal operating state, the inverter circuit 14 is PWM-controlled based on a speed command signal input from the outside to the control circuit, and the motor 12 is rotated. The abnormality detection circuit 18 does not output a detection signal and is in the L state.

  In this normal operating state, as shown in the truth table of FIG. 2, the input terminal D is in the H state since the power supply is turned on. As described above, since the detection signal is not output, the clock input terminal is also in the L state. The output terminal Q is also in the L state. Therefore, the LED 28 does not emit light.

  When the motor 12 is overloaded and the drive current exceeds the threshold value, the abnormality detection circuit 18 outputs a single pulse detection signal. When the detection signal is input, the control circuit 16 stops the rotation of the motor 12 under the control of the inverter circuit 14.

  A detection signal is also input to the clock pulse input terminal of the hold circuit 20. Then, according to the truth table of FIG. 2, when the input terminal D is in the H state and a pulsed detection signal is input to the clock input terminal, the output terminal Q is in the H state and the LED 28 emits light. This state is held until reset is performed as shown in FIG.

  Thus, the operator can recognize from the light emission of the LED 28 that the drive current exceeds the threshold value and the motor 12 has stopped. In this case, the selection switch 22 is connected to the second selection terminal 26 side and is in the L state because it is in the ground state. Incidentally, the input terminal S is in the L state because it is connected.

  Then, the operator recognizes the abnormality of the motor 12 and operates the selection switch 22 to connect to the first selection terminal 24 side. Then, as shown in the truth table of FIG. 2, R is in the H state, the reset state, the input terminal Q is in the L state, and the LED 28 is turned off. As a result, it is reset.

  As described above, in the driving device 10 of the present embodiment, the abnormality detection hold state continues and the LED 28 emits light until the operator resets using the selection switch 22. Therefore, the operator can reliably detect the abnormal state of the motor 12.

(3) Modification Example In the above embodiment, the motor 12 is determined to be abnormal when an overcurrent occurs. However, the present invention is not limited to this, and it is determined whether the motor 12 is in an overload state by detecting a power supply voltage. May be. In addition, a detection signal may be output when it is determined that the motor 12 is locked by a signal from the Hall IC that detects the rotation speed of the motor 12.

  In the above-described embodiment, the hold circuit 20 is described as an integrated D flip-flop circuit and RS flip-flop circuit. Instead, a D flip-flop circuit and an RS flip-flop circuit are formed separately. Then, the same operation as described above may be performed.

  Furthermore, in the above-described embodiment, the brushless DC motor driving device has been described.

  The motor driving device of the present invention is suitable as a motor driving device for an electric tool or an electric device, for example.

It is a block diagram of the drive device of the motor which shows one Embodiment of this invention. It is a truth table of a hold circuit. It is a timing chart in a hold circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Drive apparatus 12 Motor 14 Inverter circuit 16 Control circuit 18 Abnormality detection circuit 20 Abnormality detection signal hold circuit 22 Selection switch 24 1st selection terminal 26 2nd selection terminal 28 LED

Claims (6)

An inverter circuit for supplying drive current to the motor;
An abnormality detection circuit that detects an abnormal state of the motor and outputs a pulsed detection signal;
A control circuit that controls the inverter circuit and stops or decelerates the rotation of the motor when the detection signal is input;
In a motor drive device having
An abnormality detection signal holding means for continuously informing an abnormal condition when the detection signal is input;
Reset means for resetting the notification state in the abnormality detection signal hold means;
The motor drive device characterized by having. The abnormality detection signal hold means is a D-type flip-flop circuit,
The motor driving apparatus according to claim 1, wherein the detection signal is input to a clock pulse input terminal of the D-type flip-flop circuit, and an electronic element for notifying abnormality is connected to an output terminal Q. The reset means is an RS flip-flop circuit,
The selection switch is connected to the input terminal R of the RS flip-flop circuit, and the electronic element for notifying the abnormality is connected to the output terminal Q,
The motor drive device according to claim 1, wherein a DC power source is connected to one selection terminal of the selection switch, and the other selection terminal is grounded. The abnormality detection signal hold means and reset means are D-type and RS-type integrated flip-flop circuits,
The detection signal is input to the clock pulse input terminal of the integrated flip-flop circuit, an electronic element for notifying abnormality is connected to the output terminal Q, a reset selection switch is connected to the input terminal R,
The motor drive device according to claim 1, wherein a DC power source is connected to one selection terminal of the reset selection switch, and the other selection terminal is grounded. The motor driving device according to claim 1, wherein the electronic element is an LED. The motor driving apparatus according to claim 1, wherein the motor is a brushless DC motor.

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