JP2017021457A - Transformer input smoothing circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that a voltage is dropping at a discharging time of a smoothing capacitor having passed a maximum value of ripple charging of a rectified voltage, and a discharging power for a load current increase/decrease followed by a voice signal is also dropping, and a speaker driving force of an amplifier becomes unstable, and even at the discharging time not including such a charging time, a charging operation is obtained, and a high sound quality is obtained by an improvement of the speaker driving force of the amplifier.SOLUTION: A transformer input smoothing circuit is provided, in which even when the charging of a smoothing capacitor at the ripple maximum value interval is stopped, a ripple due to a load turns a L1 ripple current generated by C1 and C2 circuits into a connection 2 that becomes a ripple current reversed to L2 so that a voltage generated in a power supply voltage +L2 is charged to C2, and the voltage generated in the C2 charged voltage +L2 is discharged, and the charging and the discharging are increased, and a transformer input smoothing circuit for increasing the power supply to the load is provided.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power supply smoothing circuit for audio equipment.

  The smoothing circuit in general audio equipment is mainly a capacitor input type, and a smoothing capacitor is used.

  Ripple (pulsating flow) after rectifying AC is obtained by a smoothing capacitor, but when there is no power consumption, the smoothing capacitor is not discharged and the maximum voltage is charged, and ripple occurs due to the continuation of the maximum value. Although it is not, as the load increases, the potential difference between charging and discharging of the capacitor increases and the ripple increases.

  From the maximum value to the minimum value of the ripple of the rectified voltage, the maximum value has passed when the capacitor has been charged, and the voltage during discharging has been decreasing. And driving the speaker becomes unstable, which causes distortion sound.

  Even in such a discharge, the problem is to improve the sound quality by improving the speaker driving force of the amplifier by obtaining a charging effect and increasing the discharging power.

A transformer input smoothing circuit is provided to increase charging and discharging in response to a ripple current change caused by a load even during the charging pause of the smoothing capacitor.
A 100V power transformer can be used, and a transformation ratio of 100: 3 to 100: 10 or a secondary coil of about 3: 3 is possible.

Each coil of the multi-winding transformer is connected in series with the capacitor + side.
At this time, a coil is connected to the power source + and a capacitor is connected to the power source −.
In order to easily generate a current in the coil, a capacitor is connected in parallel to one of the coils, and this is used as a primary coil.
Connect the wires so that the primary coil current direction is opposite to the secondary coil current direction.
As such, charging and discharging currents of capacitors connected in series to both coils are passed through both coils.
When the number of coil turns on one side is large, a capacitor is connected in parallel to the coil on the larger side, which is used as the primary coil, and the number of turns is the secondary coil.
A small-capacitance capacitor is connected in parallel to prevent noise caused by transient currents in both coils.

When there is no ripple, the capacitor voltage in series with the coil is equal to the power supply voltage.
In this state, when a ripple occurs, an AC voltage is generated in the primary coil and the secondary coil due to the inflow and outflow of the capacitor current.
The capacitor and the coil are in series, and the voltage change of the coil is added to the DC voltage stored in the capacitor in series.

Due to the connection in which the primary coil current is opposite to the secondary coil current, the secondary coil voltage is reversed with respect to the positive side of the power supply, resulting in a negative voltage during charging and a positive voltage during discharging. When (voltage + coil voltage) is charged and (charge voltage + coil voltage) is discharged, charging and discharging are increased, and current supply to the load can be increased.
Even during charging suspension at the interval of the rectification ripple maximum value, a voltage obtained by inverting the ripple voltage generated in the primary coil to the secondary coil is added, and charging and discharging are increased.

  When ripple due to power supply rectification and ripple due to load current fluctuation occur, the transformer input smoothing circuit is connected in parallel with the power supply, and when charging the capacitor in series with the secondary coil, (power supply voltage + coil voltage) is charged. When discharging, (charging voltage + coil voltage) is discharged, and by adding a coil ± voltage, when the load current decreases, the charge increases, when the load current increases, the discharge increases, and the current of the audio signal increases and decreases It is possible to further increase the power supply at this timing, and this is easily reflected in the speaker playback sound as an improvement in the speaker braking power of the amplifier and a reduction in distortion.

3 is a transformer input smoothing circuit showing an embodiment of the present invention. The transformer input smoothing circuit corresponding to the positive / negative 2 power supply which shows the Example of this invention.

A transformer input smoothing circuit increases charging and discharging based on a DC power source smoothed by a capacitor.
In addition to the rectifying and smoothing circuit of audio equipment, the DC power supply can be implemented with a battery or an AC-DC adapter, and can be implemented by parallel connection.
Since the transformer capacity only needs to be able to handle AC current due to ripple, it can be about 1/10 of the rated power supply current.
Since an existing 100V power transformer is used, the effect can be obtained even if the voltage ratio is about 100: 3 to 100: 12, but 100: 3 with a small number of secondary turns can easily generate ripple current in the coil. .
Since it is more preferable that the number of turns of the primary coil is smaller, a 3V2 circuit (3: 3) can be selected using only the secondary coil.
As for the capacity of the coil and the series capacitor, it is preferable to select a capacity as large as possible in accordance with the power supply capacity and the mounting cost. Conversely, even if the capacity is lowered for convenience, it is easy to ensure the effect of reducing the distortion in the high sound range.

An embodiment of a transformer input smoothing circuit that obtains an operational effect by being incorporated in a DC power source of a general amplifier, a CD player, or other audio equipment, or by wiring connection will be described.
The standard of the existing 100V transformer used in the embodiment of FIG. 1 uses a secondary rated current of 0.33A, 3V (2 circuits), and the primary 100V is not necessary, so it is open.

The positive and negative poles of C1 and C2 are connected in series to L1 and L2 of the transformer, respectively, and the DC voltage + V and -V of the power supply is input to both ends of the transformer, but due to the charging and discharging of C1 and C2, Connection 2 with the current direction of L1 reversed.
Note that if the position of C1 and C2 is set to the power supply + side, the direction of current to the coil changes, which is not possible.
The current is increased by C3 in parallel with L1, but since the current decreases when a certain capacity is exceeded, there is an upper limit of the capacity.
C4 and C5 are for noise prevention, and the values required to reduce noise by inputting a transient waveform (square wave).
The capacitance of the capacitor was set to 2000μF for C1 and 10000μ for C2 and C3 in consideration of the mounting space and effects on cost.
The withstand voltage of C1 and C2 must be higher than the power supply voltage, but C3, C4, and C5 are set to 5 V because of the small voltage associated with the ripple.

As a test of simple functional operation, connect dry batteries 1,5V to 3V as the power supply, connect the test bar + to the L2 + side in the analog tester DC 0.1V range, connect the test bar-to the L2− side, and between the power supplies When the battery is discharged at the moment of short-circuit contact with the 0Ω cord, the needle swings back to +, and when it is released, the needle swings to-.
As a result, when discharging, the C2 voltage and the L2 instantaneous voltage generated in the forward direction are increased, and when released, the power supply voltage and the L2 instantaneous voltage generated in the forward direction are increased, and it can be confirmed that C2 is charged. .

  There is another set of methods to make the power supply positive and negative, but if it is shown in FIG. 4, it is not necessary to double the number of parts.

1 Compound winding transformer
2 Connection for reverse current
L1 primary coil
L2 secondary coil
C1 Primary series electrolytic capacitor
C2 Secondary series electrolytic capacitor
C3 L1 parallel electrolytic capacitor
C4 L2 noise prevention capacitor
C5 L1 noise prevention capacitor
1μF ~ 10000μF Indicates capacitor capacity
3: 3 Voltage ratio of secondary 2 circuit in 100V power transformer
100: 3: 3 100V power transformer voltage ratio + V power supply + connection-V power supply-connection
0V power supply midpoint connection

Claims (3)

  When the positive poles of capacitors C1 and C2 are connected in series to the coils L1 and L2 of the double-winding transformer to which the power supply and the pole are connected, respectively, Transformer input smoothing circuit with capacitor C3 connected in parallel to L1 with connection 2 in which the current direction is reversed.   2. The transformer input smoothing circuit according to claim 1, further comprising noise preventing capacitors C4 and C5 connected in parallel to the coils L1 and L2.   A voltage equal to the power supply voltage is charged in the capacitors C1 and C2, and the current direction of the coil L1 due to charging and discharging is opposite to that of the coil L2. When the capacitor C2 is discharged, + is generated on the power supply + side of the coil L2, so that (power supply voltage + L1 voltage) is charged to the capacitor C2 during charging, and (C2 voltage + L2 voltage) is discharged during charging. The transformer input smoothing circuit according to claim 1, wherein as a result of discharging to the power source, charging is increased and discharging is increased, thereby obtaining an increase in power supply to the load.

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