KR100192957B1 - Dc motor malfunction protecting circuit by inrushing current - Google Patents

Abstract

The malfunction prevention circuit by the initial inrush current of the disclosed DC motor includes a motor protection circuit which detects the overcurrent flowing into the DC motor through the relay by the overcurrent integration method and controls the driving of the DC motor. It is to prevent the malfunction due to the initial initial inrush current when the power is supplied.

According to the present invention, the motor driving unit 10 turns on / off the transistor Q1 according to the motor driving signal ON, and the driving of the relay 20 is controlled as the transistor Q1 is turned on / off, so that the DC power supply (Vdc) ) Is supplied to the DC motor 30, the current flowing through the DC motor 30 is detected by the resistor Rs, and the overcurrent integrating unit 40 refers to the voltage Vs of the resistor Rs. The overcurrent component is detected by integrating on the basis of the voltage Vref1, and the output voltage Vamp of the overcurrent component detected by the overcurrent integrating unit 40 is compared with the reference voltage Vref2 set by the motor protection unit 50 in advance. When the overcurrent flowing to the DC motor 30 is detected and the overcurrent is detected, the motor driving unit 10 is reset to protect the DC motor 30, and the DC power supply Vdc is supplied to the DC motor 30. Is detected by the initial inrush current compensation means 60 for a preset initial time. Not initially to drive the direct current motor (30) over current integration unit 40 does not operate the motor protection circuit according to the initial rush current is prevented by a malfunction signal to block current flowing in the integration section 40.

Description

Malfunction prevention circuit by initial inrush current of DC motor

The present invention relates to a malfunction prevention circuit caused by an initial inrush current of a direct current motor that prevents the occurrence of a malfunction in driving of the direct current motor by the initial inrush current.

More specifically, the motor protection circuit which detects the overcurrent flowing into the DC motor by the overcurrent integration method and protects the DC motor from being damaged, provides an initial inrush current generated during the initial supply of DC power to the DC motor through a switching element. The present invention relates to a malfunction prevention circuit caused by an initial inrush current of a DC motor that detects and prevents a malfunction of stopping the DC motor.

In general, in the case of supplying and driving operating power to a DC motor using a switching device such as a mechanical relay or a power semiconductor element, overcurrent is often supplied due to mechanical restraint of the DC motor.

Therefore, when driving a DC motor, it is necessary to detect whether overcurrent is supplied to the DC motor and, when the supply of overcurrent is detected, to turn off the switching element according to the overcurrent detection signal to protect the DC motor from damage by overcurrent. have.

BACKGROUND ART Conventionally, an overcurrent protection circuit of a DC motor is provided to detect a DC current by an integral method and protect the DC motor from an instantaneous overload due to mechanical restraint of the DC motor or slightly overcurrent exceeding a reference current.

As shown in FIG. 1, the overcurrent protection circuit of the conventional DC motor includes the motor driver 10 for turning on and off the transistor Q1 by the motor driving signal ON, and the on / off of the transistor Q1. Relay 20 for controlling the supply of DC power (Vdc) to the DC motor 30 while driving is controlled according to the OFF, a resistor (Rs) for detecting a current flowing through the DC motor 30, and the resistance An overcurrent integrating unit 40 which detects overcurrent by integrating the voltage Vs at both ends of Rs with the operational amplifier OP1, the resistor Rin, and the capacitor Cin based on the reference voltage Vref1; The output voltage Vamp of the overcurrent integrating unit 40 is compared with the preset reference voltage Vref2 by the comparator COM1 to detect the overcurrent, and when the overcurrent is detected, the motor driving unit 10 is reset to reset the direct current. The motor protector 50 protects the motor 30 from overcurrent. I did it.

In the conventional overcurrent protection circuit configured as described above, when the motor driving signal ON is input while the DC power supply Vdc is applied, the motor driving unit 10 outputs a high potential so that the transistor Q1 is turned on. As Q1 is turned on, the relay 20 is driven to connect its male position.

Then, since the DC power supply Vdc flows to the ground through the switch, the DC motor 30, and the resistor Rs of the relay 20 sequentially, the DC motor 30 is driven.

At this time, a voltage drop occurs in the resistor Rs according to the current flowing through the DC motor 30, and the voltage Vs at both ends of the resistor Rs is proportional to the amount of current flowing through the DC motor 30.

The voltage Vs at both ends of the resistor Rs is input to the overcurrent integrating unit 40 and integrated based on the reference voltage Vref1, and the integral output voltage Vamp of the overcurrent integrating unit 40 is a motor protection unit ( 50 is input to the comparator COM1 to be compared with a preset reference voltage Vref2.

When the output voltage Vamp of the overcurrent integrating unit 40 is lower than the set reference voltage Vref2 as a result of the comparison of the motor protecting unit 50, the motor protecting unit 50 outputs a high potential and thus the motor driving unit 10. Is not reset, and continues to be driven normally, turning on the high potential output and transistor Q1 to continue to drive motor 30.

When the output voltage Vamp of the overcurrent integrating unit 40 is higher than the set reference voltage Vef2 as a result of the comparison of the motor protection unit 50, the overcurrent flows to the DC motor 30 and the motor protection unit 50 is The low potential is output, and the output low potential is applied to the reset terminal RESET of the motor driving unit 10 as a reset signal. Therefore, the motor driving unit 10 outputs the low potential and turns off the transistor Q1 so that the relay ( 20) is stopped and the DC motor 30 is stopped.

In the conventional overcurrent protection circuit, not only the general overcurrent but also the initial inrush current generated when the DC motor 30 is initially started, as shown in the operation waveform diagram of FIG. Integral was used.

Therefore, when the detection level of the overcurrent is set to be detected based on the smaller than the area S1 in which the inrush current is integrated, a malfunction occurs in which the inrush current is also detected as the overcurrent to stop the DC motor 30.

Therefore, when the overcurrent flows over the area S4 based on the area S4 larger than the area S1 in which the initial inrush current is integrated, and not based on the area S1 in which the initial inrush current is integrated. Since the DC motor 30 is stopped and the damage caused by the overcurrent is prevented, when the overcurrent flows to the DC motor 30 below the initial inrush current, for example, the integral area S2 or the integrated area S3, this integral An overcurrent is not detected as much as the area S2 or the integrated area S3, and the DC motor 30 is continuously driven so that the DC motor 30 is damaged by an overcurrent below the initial inrush current.

Accordingly, an object of the present invention is to provide a DC motor in the early stage of driving the DC motor even if the detection level of the overcurrent is set below the initial inrush current by bypassing and blocking the input signal of the overcurrent protection unit for a predetermined time during the initial stage of driving the DC motor. It is to provide a malfunction prevention circuit by the initial inrush current of the DC motor to prevent the malfunction by the initial inrush current flowing to the.

According to the malfunction prevention circuit due to the initial inrush current of the DC motor of the present invention for achieving the above object, the motor driving unit turns on / off the transistor in accordance with the motor driving signal, and the driving of the relay is performed as the transistor is on / off. It controls the DC power supplied to the DC motor, detects the current flowing to the DC motor as a resistor, and detects the overcurrent by integrating the overcurrent integral part of the resistor based on a reference voltage. The output voltage of the integral part is compared with the preset voltage of the motor protection part to detect the overcurrent, and if the overcurrent is detected, the motor driving part is reset to protect the DC motor, and the initial DC power supplied by the relay to the DC motor is Seconds preset by the inrush current compensation means By blocking the signal to be integrated during the time overcurrent inflow portion is initially to drive a DC motor to prevent erroneous operation of the protection circuit according to the initial inrush current.

1 is a driving circuit diagram of a conventional DC motor.

2 is an operation waveform diagram of each part of FIG.

3 is a driving circuit diagram of a DC motor provided with a malfunction preventing circuit according to the present invention.

4 is an operational waveform diagram of each part of FIG.

* Explanation of symbols for main parts of the drawings

10: motor drive unit 20: motor drive relay

30: motor 40: overcurrent integral

50: motor protection unit 60: initial inrush current compensation means

Hereinafter, with reference to the drawings of Figures 3 and 4 showing a preferred embodiment of the malfunction prevention circuit by the initial inrush current of the DC motor according to the present invention will be described in detail, where the same reference numerals are given to the same parts as in the prior art.

3 is a circuit diagram showing an embodiment of a malfunction preventing circuit caused by an initial inrush current of a DC motor according to the present invention.

As shown in FIG. 2, the motor driving unit 10 for turning on / off the transistor Q1 by the motor driving signal ON and the DC power supply Vdc are controlled while driving is controlled as the transistor Q1 is turned on / off. A relay 20 for intermittently being supplied to the DC motor 30, a resistor Rs for detecting a current flowing through the DC motor 30, and a voltage Vs between both ends of the resistor Rs may be used. OP1), the resistor (Rin) and the condenser (Cin) is integrated based on the reference voltage (Vref1) to detect the overcurrent portion 40 and the output voltage (Vamp) of the overcurrent integral portion 40 The comparator COM1 compares the preset reference voltage Vref2 to detect whether overcurrent flows to the DC motor 30, and resets the motor driver 10 when the flow of overcurrent is detected to reset the DC motor ( An electric motor protection part 50 which protects 30, and the said DC motor 30 During direct-current power supply (Vdc) time preset on the initial which the feed is composed of the over-current integration section 40, the initial rush current compensation means (60) for blocking the signal to be introduced into.

The initial inrush current compensating means 60 includes a transistor Q2 for bypassing a signal flowing into the overcurrent integrating unit 40 to ground while being turned on by the initial inrush current, and the relay 20 is driven to When supplying the DC power supply (Vdc) to the DC motor 30, the resistance (R1) for determining the time to turn on the transistor Q2 by controlling the current flowing to the base of the transistor (Q2) to a predetermined time constant value and When the capacitor C1 and the DC power supply Vdc are cut off, the charging power of the capacitor C1 is discharged so that the relay 20 is driven while the DC power supply Vdc is supplied. It consists of a diode D1 which causes C1) to charge a new charge.

Here, the driving time of the initial inrush current compensating means 60 depends on the time constant values of the resistor R1 and the condenser C1, and the inflow time of the initial inrush current of the DC motor 30 is different. Since the inrush time of the initial inrush current is different depending on the value of the DC power supply (Vdc) even in the same DC motor 30, the time constant of the resistor (R1) and the capacitor (C1) longer than the time considering all of these situations The value is adjusted to set the on time of the transistor Q1.

The malfunction prevention circuit by the initial inrush current of the DC motor of the present invention configured as described above can be classified according to the operation of the initial inrush current compensation means 60. The relay 20 in which the initial inrush current compensation means 60 operates. During a predetermined time during the initial driving of the initial inrush current compensation means 60 cuts off the signal input to the operational amplifier dog OP1 through the resistance (Rin) of the overcurrent integrating unit 40 in accordance with the driving of the relay 20 It is possible to prevent the malfunction of the overcurrent integrating unit 40 due to the initial inrush current generated.

In the case where the initial inrush current compensating means 60 does not operate, the current flowing in the DC motor 30 is integrated in the overcurrent integrator 40 in the overcurrent portion as the motor protection circuit operates in the same manner as the conventional case. The output signal of the motor protection unit 50 changes according to the integration result, and the DC motor 30 can be protected from overcurrent by outputting the reset signal to the motor driving unit 10.

Here, looking at the case where the initial inrush current compensating means 60 operates, the initial time (section from t0 to t1 in FIG. 4) until the relay 20 is driven and the initial inrush current flows in the DC motor 30. That is, when the driving signal ON is applied to the motor driving unit 10 at the time t0 and the transistor Q1 is turned on, the relay 20 is driven so that the DC power supply Vdc passes through the switch of the relay 20. Since it is applied to the electric motor 30, a current flows to the DC motor 30 and starts to be driven.

At this time, the resistor Rs converts the current flowing through the DC motor 30 into a voltage to output the detection voltage Vs as shown in FIG.

At the same time, a DC power supply Vdc applies a switch of the relay 20 to a terminal of the opposite DC motor 30 to which the sensing resistor Rs is connected, and the DC power supply Vdc is applied to the initial inrush current compensation means 60. Since a predetermined current flows to the base of the transistor Q2 while being charged to the capacitor C1 through the resistor R1, the transistor Q2 remains on until the capacitor C1 is completely charged with power. Done.

Accordingly, the detection voltage Vs passing through the resistor Rin of the overcurrent integrating unit 40 during the initial time t0 to t1 is bypassed to the ground through the transistor Q2, and the calculation of the overcurrent integrating unit 40 is performed. Since it is not applied to the amplifier OP1, the output voltage Vamp of the operational amplifier OP1 does not change.

In this state, when the time constant time set by the resistor R1 and the capacitor C1 elapses, the power is completely charged in the capacitor C1 and the transistor Q2 is turned off, so that the initial inrush current compensating means 60 does not operate. The detection voltage Vs of the resistor Rs is input to the overcurrent integrating unit 40 and is integrated after the integration of the resistor Rin and the capacitor Cin to the DC motor 30. When the overcurrent flows, the protection circuit operates to prevent the DC motor 30 from being damaged by the overcurrent.

The diode D1 of the initial inrush current compensating means 60 discharges the power that was charged in the capacitor C1 in a short time when the relay 20 is stopped and the DC power supply Vdc is not supplied. When the 20 is driven to drive the DC motor 20, the above function can be made again.

As described above, according to the malfunction prevention circuit due to the initial inrush current of the DC motor according to the present invention, the inrush current in the overcurrent integrator for detecting the overcurrent flowing into the DC motor by the overcurrent integrating method By blocking the inflow, it is possible to prevent the motor protection circuit from malfunctioning due to excessive inrush current at the initial stage of relay driving, and when overcurrent flows below the initial inrush current flowing to the DC motor at the initial stage of driving the DC motor. It can accurately detect and prevent the damage of DC motor.

Claims (2)

The motor driver 10 turns on / off the transistor Q1 according to the motor drive signal ON, and the driving is controlled as the transistor Q1 is turned on / off so that the DC power supply Vdc is the DC motor 30. The relay 20 for intermittently being supplied to the resistor, the resistor Rs for detecting the current flowing through the DC motor 30, and the voltage Vs between both ends of the resistor Rs based on the reference voltage Vref1. The overcurrent integrator 40 for integrating the overcurrent component and the output voltage Vamp of the overcurrent integrator 40 are compared with a preset reference voltage Vref2 to determine whether overcurrent flows to the DC motor 30. In the protection circuit of a direct-current motor provided with the motor protection part 50 which detects and the flow of an overcurrent detects and resets the motor drive part 10 and protects the motor 30 from overcurrent. 20) is driven to direct the DC motor 30 An initial inrush current that detects the initial supply of the source Vdc and blocks the voltage of both ends of the resistor Rs from flowing into the overcurrent integrating unit 40 for a predetermined time in the initial period when the DC power supply Vdc is supplied. Malfunction prevention circuit due to the initial inrush current of the DC motor, characterized in that it comprises a compensation means (60). The method of claim 1, wherein the initial inrush current compensation means (60); A transistor (Q2) for bypassing the signal flowing into the overcurrent integrating unit (40); A resistor (R1) and a capacitor (C1) for turning on the transistor (Q2) for a preset time constant time at which the relay (20) is driven to supply a DC power supply (Vdc); And discharging the charging power of the capacitor C1 when the DC power Vdc is not supplied through the relay 20 so that new charge is charged in the capacitor C1 every time the relay 20 is driven. Malfunction prevention circuit by the initial inrush current of the DC motor, characterized in that consisting of a diode (D1).