JP2009072061A - Unit for preventing counter-electromotive force - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a counter-electromotive force prevention unit for batteries, which can prevent the occurrence of noise due to the counter-electromotive force generated by loads of a battery and turning on and off of a charging generator, and which can suppress noise emanating from car audio speakers, electrical products, and malfunctioning of electronic equipment. <P>SOLUTION: A reverse-blocking diode 104 and a fuse 105 that fuses with overcurrent are connected in series between a positive lead wire 102 and a negative lead wire 103 that are connected to the positive terminal and negative terminal of a battery serving as a DC supply source, respectively. A capacitor 106 is connected in parallel with the reverse-blocking diode 104. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a back electromotive force prevention unit for a DC power source that absorbs back electromotive force generated in an inductive load.

  Taking an in-vehicle battery as an example of a DC power source, a rechargeable secondary battery is usually used as the in-vehicle battery. When the battery and the vehicle-mounted device are represented by electric circuits, they are as shown in FIG. In the figure, 20 is a battery, 21 is a cell motor, 22 is an electrical component, 23 is a generator, 24 is a starter switch, 25 is a rectifier diode, and 26 is when the electromotive force of the charging generator 23 is equal to or higher than the battery voltage. An automatic on / off switch that automatically enters is shown.

The battery 20 is represented by a pure battery Eo and an internal resistance r, a voltage drop e = ri occurs due to the output current i and the internal resistance r, and the voltage V1 at the output terminal is V1 = Eo-e = Eo-ri.
It becomes.

  The load of the battery 20 includes a cell motor 21 and an electrical component 22, but an inductance component (inductive load) exists not only in the cell motor but also in a car air conditioner and a car audio in the electrical component 22. From these inductance components, back electromotive force is generated, which becomes noise and is superimposed on the output terminal voltage.

Further, since the positive side of the charging generator 13 is turned on / off by the automatic on / off switch 16 while monitoring the voltage of the battery 10, the coil L of the charging generator 13 is opened at the time of turning off and the back electromotive force generated is generated. It is difficult to absorb power.
The back electromotive force due to such an inductance component appears as annoying noise in car audio and radio speakers, and also causes car navigation and flickering of TV images.

Conventionally, for example, as shown in FIG. 13, noise generated by the blower motor 101 is regenerated to the battery power source VB by the diode 106, and noise is reduced by the capacitor 124, and the harmonic component of the noise is attenuated by the capacitor 124. The noise between the battery power sources generated by the switching of the current is attenuated by the LC filter composed of the inductance 123 and the electrolytic capacitor i22, and the amount of noise generated when the switching element 102 is turned off is reduced by the inductance 123. There is one that reduces the voltage fluctuation between them (for example, see Patent Document 1).
JP-A-7-2839797

However, a noise filter using a capacitor or an inductance has a problem that only a harmonic component or a component of a specific frequency can be removed, and the effect of suppressing a counter electromotive force having a high peak is low.
Moreover, since the conventional noise filter is to be attached to the electrical component itself, there is a problem that it cannot be newly provided in the existing electrical component.

  The present invention has been made in view of such circumstances, and is configured to be fed from a DC power source such as a battery to a load including an inductive load via a circuit element or a circuit unit that performs a switching operation. It is an object of the present invention to provide a reverse voltage prevention unit capable of preventing the occurrence of noise due to a counter electromotive force generated by an inductive load in a circuit device or circuit unit that performs the switching operation in a circuit device.

  The back electromotive force prevention unit of the present invention that achieves the above object is configured to be fed from a DC supply source through a circuit element or a circuit unit that performs a switching operation, and is caused by an inductive load generated during the switching operation. A back electromotive force prevention unit in a circuit device that outputs noise, the cathode of which is connected to the positive terminal of the DC supply source and the anode of which is connected to the negative terminal of the DC supply source, A capacitor connected in parallel to the diode, and the diode absorbs the inductive load, and the capacitor determines a voltage on the cathode side of the diode when the power supply is turned on. Is temporarily lowered to a predetermined level, and is temporarily raised to a predetermined level when the power supply is switched off. , Characterized in that the harmonic components generated by said counter electromotive force is intended to return to the DC supply source side.

  In one embodiment, the DC supply source is a combination of a battery and a charging generator that repeats an on / off operation according to the voltage of the battery, and the charging generator also generates the back electromotive force. A circuit element is included.

  In one embodiment, the circuit device includes a comparator, an oscillator, and a transformer, and the comparator periodically increases in accordance with a comparison result between the positive polarity power of the DC supply source and the output of the oscillator. An AC signal changing between a level and a low level is output, and the transformer transforms the output of the comparator on the primary side and outputs it to the secondary side.

  ADVANTAGE OF THE INVENTION According to this invention, the influence of the noise of a circuit apparatus by the back electromotive force generated by an inductive load at the time of switching operation of the circuit element or circuit part which performs switching operation can be prevented.

  In addition, for example, by inserting the reverse voltage absorption diode of the present invention into an in-vehicle battery, it is possible to quickly suppress noise and prevent an unnecessary current from flowing back to the electrical component. As a result, the electrical component operates correctly, and the entire automobile can be operated smoothly. In addition, the noise of FM radio installed in automobiles is reduced, the sound quality is improved, and the noise of AM radio is reduced. The shift shock of automatic vehicles is eliminated, the vehicle becomes quieter, and the fuel efficiency is improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the configuration of an audio circuit to which the present invention is applied. In the figure, an audio circuit to which the present invention is applied includes a transformer 1 having input terminals 50 and 51 to which an input signal is applied, and a diode D1 connected to the secondary side of the transformer and rectifying an input AC signal. And a smoothing capacitor C1, an amplifier 2 and a speaker 3.
The smoothing capacitor C1 is connected in parallel with a diode D2 for absorbing the counter electromotive force.

  Since the amplifier 2 performs a switching operation, if the amplifier 2 is replaced with the switch 4 and an AC signal is input to the input terminals 50 and 51 of the transformer 1, the battery 5 is inserted into the secondary side of the transformer 1 with the polarity shown in the figure. The circuit shown in FIG. 2 is obtained. In order to simplify the circuit operation, the operation when the switch 4 is turned on / off in the circuit shown in FIG. 2 instead of the circuit shown in FIG. 1 will be described with reference to FIG. FIG. 3 shows the voltage waveform at the point A on the cathode side of the diode D1 when the switch 4 is on and off.

  In FIG. 2, for example, when the switch 4 is switched from the off state to the on state at time t1, the electromotive force of the battery 5 is on the switch 4 side with respect to the drive coil 3a of the speaker 3 so that the D point side is + polarity. Since the point C side is applied so as to have a negative polarity, the capacitor C1 is charged so that the point B has a positive polarity and the point A has a negative polarity. As a result, the potential at the point A starts to decrease in the negative direction from 0V and decreases to a predetermined level. Thereafter, since the electric charge accumulated in the capacitor C1 is discharged through the diode D2 and the drive coil 3a, the potential at the point A rises and returns to the original potential at time t2.

  Next, when the switch 4 is switched from the on state to the off state at time t3, the point C of the driving coil 3a has a negative polarity and the point D of the driving coil 3a has a positive polarity with respect to the driving coil 3a. Thus, the back electromotive force is generated, and the current flows into the capacitor C1 from the point A side via the diode D2. Therefore, the capacitor C1 is charged so that the point A side has a positive polarity and the point B has a negative polarity. Is done.

Therefore, the potential at the point A starts to increase in the positive direction from 0 V and increases to a predetermined level. Thereafter, the electric charge accumulated in the capacitor C1 is discharged through the diode D1 and the secondary winding of the transformer 1 so as to be returned to the battery 5 as a power source, and is discharged through the diode D2. As a result, the potential at the point A starts to drop and returns to the 0V level at time t4.
In this way, when the switch 4 is switched on and off, the potential of the point A temporarily rises as shown in FIG. 3 by the function of the smoothing capacitor C1 and the back electromotive force absorption diode D2. Or change slowly to descend.

Next, FIG. 4 shows a circuit obtained by removing the diode D2 from the circuit shown in FIG. When the switch 4 was turned on and off with this circuit, the potential waveform at the point A was almost the same as in FIG.
Next, FIG. 5 shows a circuit obtained by removing the capacitor C1 and the diode D2 from the circuit shown in FIG. FIG. 6 shows waveforms showing the potential change state at the points A and C when the switch 4 is turned on and off in this circuit. As shown in FIG. 6B, it can be seen that when the switch 4 is switched from the on state to the off state, the potential at the point A changes greatly compared to the case shown in FIG.

Further, as shown in FIG. 6C, a vibration waveform that decays with time is observed in the potential (back electromotive force) at point C when the switch 4 is switched from the on state to the off state. At this time, the potential at the point D has a waveform obtained by inverting the potential at the point C.
Next, FIG. 7 shows a circuit in which the capacitor C1 is removed from the circuit shown in FIG. 2 and the diode D2 is left. FIG. 8 shows a potential waveform at point A when the switch 4 is turned on and off in this circuit. As shown in FIG. 8A, the potential waveform at the point A when the switch 4 is switched from the OFF state to the ON state is completely the same as in the case of the circuit shown in FIG. 5 (the waveform shown in FIG. 6A). Not the same, but little change.

  On the other hand, the potential waveform at the point A when the switch 4 is switched from the on state to the off state is as shown in FIG. 8B in the case of the circuit shown in FIG. 5 (FIG. 6B). It can be seen that it changes greatly. This is because, in the circuit shown in FIG. 5, the potential waveform at point A when the switch 4 switches from the on state to the off state, that is, the potential waveform at point A shown in FIG. This is because the waveform obtained by inverting the waveform shown in (c) is superimposed.

  As described above, the diode D2 absorbs the back electromotive force generated in the drive coil 3a of the speaker 3 when the switch 4 is switched from the on state to the off state by the diode D2 connected in parallel to the smoothing capacitor C1. D1 is supplied to the battery 5 via the secondary winding of the transformer 1.

In the circuit shown in FIG. 2, the back electromotive force generated in the drive coil 3a of the speaker 3 when the switch 4 is switched from the on state to the off state is absorbed by the diode D2, and the point A has a positive polarity. , B is recharged so that it has a negative polarity. This capacitor C1 has not only the original function of smoothing the pulsating current after the AC signal is rectified by the diode D1, but also the function of smoothing the counter electromotive force generated in the inductive load such as the drive coil 3a of the speaker 3. Have.
When the power source is a battery, the capacitor C1 has a function of returning harmonic components generated by back electromotive force generated in an inductive load such as the drive coil 3a of the speaker 3 to the battery side.

  Next, FIG. 9 shows a configuration example of a switching power supply to which the present invention is applied. In the figure, a rectifier circuit 10, a capacitor C10 for smoothing the output voltage of the rectifier circuit 10, a back electromotive force absorption diode D11 connected in parallel to the capacitor C10, a comparator 11, an oscillator 12, a transformer 13, and the like. , Diodes D12 and D13, a coil L1, and a smoothing circuit including a capacitor C12.

  In the switching power supply having the above configuration, the comparator 11 to which the output of the rectifier circuit 10 and the output of the oscillator 12 are input, is periodically switched between a high level and a low level according to the comparison result between the output of the rectifier circuit 10 and the output of the oscillator 12. An AC signal (for example, a 100 kHz pulse signal) that changes between the levels is output, transformed by a transformer 13, rectified by a diode D12, and smoothed by a smoothing circuit including a coil L1 and a capacitor C12. Is output to the output terminals 62 and 63.

Since the switching power supply having the above configuration includes a large number of inductances which are inductive loads, each time switching is performed by the comparator, the transformer 13 and the coil L1 are reversed each time, as in the case of the driving coil of the speaker of the audio circuit described above. Although an electromotive force is generated, the counter electromotive force generated by connecting a diode in parallel with the smoothing capacitor C10 in parallel with the polarity shown in FIG. 9 can be absorbed.
As a result, unnecessary back electromotive force can be re-supplied to the smoothing capacitor, noise can be prevented, and power consumption can be reduced by the amount of back electromotive force.

Next, FIG. 10 shows a specific configuration of the back electromotive force unit according to the embodiment of the present invention.
FIG. 10 shows an appearance of the back electromotive force prevention unit 100 according to the embodiment of the present invention. A backflow prevention diode 104 and a fuse 105 are connected in series between a positive lead wire 102 and a negative lead wire 103. A capacitor 106 is connected in parallel to the backflow prevention diode 104. The fuse 105 is detachable from the fuse socket 107 so that it can be replaced when the fuse 105 is melted. Crimp terminals 108 and 109 are attached to the tips of the positive lead wire 102 and the negative lead wire 103 to ensure contact when connecting to the positive electrode and negative electrode of the battery, and to reduce the contact resistance. ing.

  FIG. 11 is a circuit diagram showing a state in which the back electromotive force prevention unit 100 according to the present invention is connected to the battery 110. In the figure, 111 is a cell motor, 112 is an electrical component, 113 is a generator, 114 is a starter switch, 115 is a rectifier diode, and 116 is automatically when the electromotive force of the charging generator 113 exceeds the battery voltage. The automatic on / off switch is shown. Note that the back electromotive force prevention unit 100 is actually directly connected to the positive terminal and the negative terminal of the battery 10.

  As described above, the load of the battery 110 includes the cell motor 111 and the electrical component 112. In addition to the cell motor, an inductance component also exists in the car air conditioner, the car audio, and the like in the electrical component 112. From these inductance components, back electromotive force is generated, which becomes noise and is superimposed on the output terminal voltage.

  Further, since the positive side of the charging generator 113 is turned on and off by the automatic on / off switch 116 while monitoring the voltage of the battery 110, the coil L of the charging generator 113 is opened at the time of turning off and the back electromotive force generated is generated. It is difficult to absorb power.

  However, by providing the back electromotive force prevention unit 100, the back electromotive force generated from the inductance components of the cell motor 111, the electrical component 112, and the charging generator 113 flows into the backflow prevention diode 104 and is absorbed. It will not appear at the output terminal.

In this way, by inserting the backflow prevention diode 104 into the battery 110, noise can be quickly suppressed, and unnecessary current can be prevented from flowing back to the electrical components. Note that the harmonic noise in the forward and reverse directions can be absorbed by the capacitor 106. Also, in the unlikely event that the capacitor 106 or the backflow prevention diode 104 fails and is short-circuited, the fuse 105 is melted by a large current flowing from the battery 110 to prevent an accident.
In addition, as the capacity | capacitance of the capacitor | condenser 106, when the battery 110 is 12V rating, what is about 0.47 micro F and withstand voltage | pressure 250V can be used.

The circuit diagram showing the composition of the audio circuit to which the present invention is applied. The figure which replaces the amplifier of the audio circuit shown in FIG. 1 with a switch, and shows the circuit which inserted the battery into the secondary side of the transformer instead of inputting an alternating current signal into a transformer. FIG. 3 is a diagram showing a potential waveform at a point A when the switch 4 is turned on and off in the circuit shown in FIG. 2. The figure which shows the circuit which removed the diode D2 from the circuit shown in FIG. The figure which shows the circuit which removed the capacitor | condenser C1 and the diode D2 from the circuit shown in FIG. FIG. 6 is a waveform diagram showing a potential change state at points A and C when the switch 4 is turned on and off in the circuit shown in FIG. 5. The figure which removes the capacitor | condenser C1 from the circuit shown in FIG. 2, and shows the circuit which left the diode D2. FIG. 8 is a waveform diagram showing a potential change state at point A when the switch 4 is turned on and off in the circuit shown in FIG. 7. The figure which shows the structural example of the switching power supply with which this invention is applied. The figure which shows the external appearance of the back electromotive force prevention unit which concerns on embodiment of this invention. The circuit diagram which shows the state which connected the back electromotive force prevention unit which concerns on this invention to the battery. The electric circuit diagram of a vehicle-mounted battery and a vehicle-mounted apparatus. The circuit diagram which shows the example of the conventional noise filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transformer 2 ... Amplifier 3 ... Speaker 3a ... Drive coil 4 ... Switch C1 ... Capacitor D1, D2 ... Diode 100 ... Back electromotive force prevention unit 102 ... Positive side lead wire 103 ... Negative side lead wire 104 ... Backflow prevention diode 105 ... Fuse 106 ... Capacitor 107 ... Fuse socket 108, 109 ... Crimp terminal 110 ... Battery 111 ... Cell motor 112 ... Electrical component 113 ... Generator 114 ... Starter switch 115 ... Rectifier diode 116 ... Automatic on / off switch

Claims (3)

A back electromotive force prevention unit in a circuit device configured to be fed from a DC supply source through a circuit element or a circuit unit that performs a switching operation and that outputs noise due to an inductive load generated during the switching operation. There,
A diode whose cathode is connected to the positive terminal of the DC source and whose anode is connected to the negative terminal of the DC source;
A capacitor connected in parallel to the diode;
The diode absorbs the inductive load,
The capacitor temporarily lowers the voltage on the cathode side of the diode to a predetermined level when the power supply is switched on and temporarily increases the voltage to a predetermined level when the power supply is switched off. And, the harmonic component generated by the back electromotive force is returned to the DC supply source side,
Back electromotive force prevention unit. The DC supply source is a combination of a battery and a charging generator that repeats an on / off operation according to the voltage of the battery,
The charging generator also includes a circuit element that generates the counter electromotive force,
The back electromotive force prevention unit according to claim 1. The circuit device includes a comparator, an oscillator, and a transformer.
The comparator outputs an AC signal that periodically changes between a high level and a low level according to a comparison result between the positive polarity power of the DC supply source and the output of the oscillator.
The transformer is characterized in that the output of the comparator on the primary side is transformed and output to the secondary side,
The back electromotive force prevention unit according to claim 1.

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