JP2791353B2 - Power circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses harmonic current,
Also, the present invention relates to a power supply circuit capable of handling a plurality of types of voltages.

[0002]

2. Description of the Related Art In a power supply circuit for rectifying an alternating current and supplying it to a load, a coil 84 composed of a single winding is conventionally connected in series to an output line of an alternating current power source 81 as shown in FIG. The impedance reduces the peak value of the output current from the rectifier circuit 82 that rectifies the AC from the AC power supply 81, that is, the peak value of the current charged in the capacitor of the smoothing circuit 83, and increases the energization time to increase the harmonic current. Wave current was suppressed.

[0003] By the way, the world has a commercial power supply voltage of 10
Since there are a 0 volt system area and a 200 volt system area, the power supply circuit needs to change the inductance of the coil 84 depending on each area.

That is, a coil of a power supply circuit used in a region of 100 volts has an inductance 1/4 and requires twice the allowable current as compared with a coil of a region of 200 volts. If the coil corresponding to each power supply voltage is designed exclusively, the coil of the power supply circuit used in the 100 volt area has twice the winding cross-sectional area and the number of turns of 1/200 as compared with that of the 200 volt area. Two times.

In a conventional power supply circuit, the above-mentioned two types of coils are prepared, and a coil having an inductance corresponding to the voltage of a commercial power supply in an area of a shipping destination is selected and mounted.

[0006]

As described above, if a plurality of types of coils having different inductances were prepared and the coils mounted on the circuit were changed depending on the shipping destination, the manufacturing cost and Management costs increase.

An object of the present invention is to provide a small and inexpensive power supply circuit capable of handling a plurality of types of power supply voltages by switching the connection state of a plurality of windings having a common core.

[0008]

The present invention comprises an AC power supply,
A rectifier circuit for rectifying an AC output generated from the AC power supply, a smoothing circuit for smoothing an output voltage of the rectifier circuit,
In a power supply circuit having an output line of the AC power supply or a coil for suppressing harmonic current provided on an output line of the rectifier circuit, the coil is configured by a plurality of windings wound around a common core, The coil is composed of a first winding and a second winding wound on a common core .
1. Select the second winding in parallel with each other or in series with each other
The above-mentioned problem is solved by providing a switching means connected to the switch.

Further, the present invention comprises an AC power supply, a rectifier circuit for rectifying an AC output generated from the AC power supply, and two capacitors connected in series between two output lines of the rectifier circuit. In a power supply circuit including a smoothing circuit for smoothing an output voltage of the rectifier circuit and a coil for suppressing a harmonic current provided on an output line of the rectifier circuit, the coil is wound around a common core. And each of the windings is provided on each output line of the rectifier circuit, and switching means is provided between a connection point between the capacitors and one power supply line of the AC power supply. Is selectively turned on / off according to the voltage of the AC power supply, thereby solving the above-mentioned problem.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment will be described. In this example, a coil for suppressing harmonic current is provided on an output line of an AC power supply.

FIG. 1 shows a circuit configuration. In the figure, 1
1 is an AC power supply, 12 is a rectifier circuit such as a diode bridge for rectifying an AC output generated from the AC power supply 11, 13 is a capacitor, and is a smoothing circuit for smoothing an output voltage from the rectifier circuit 12, and 14 is an AC power supply. This is a coil for suppressing harmonic current provided on the output line of the power supply 11. The coil 14 includes a winding 14 wound around a common core.
a and 14b. Switching means are constituted by switches 14c, 14d and 14e for switching the windings 14a and 14b in parallel or in series. In this example, the number of turns and the inductance of the windings 14a and 14b are both equal, and are N and L, respectively. Reference numeral 15 denotes a switching regulator that stabilizes the output voltage from the smoothing circuit 13 and supplies the output voltage to the load 16.

Next, the operation will be described. First, when the voltage of the AC power supply 11 is a 200 volt system (in this example, 230 volts), the switches 14c and 14e are opened and the switch 14d is closed. Thereby, the winding 14
a and 14b are connected to each other in series.

The combined inductance L2 of the coil 14 in the series connection state is as follows: L2 = (μSn2) / d = {μS (2N) 2} / d = 4 (μSN2) / d = 4L Here, S is the effective area of the core, μ is the magnetic permeability of the core, d is the magnetic path length of the core, and n is the number of turns of the winding. As described above, the combined inductance when the windings 14a and 14b are connected in series is equal to four times the inductance L of the windings 14a and 14b.

FIG. 2A shows the output voltage waveform of the AC power supply 11, FIG. 2B shows the output current waveform of the rectifier circuit 12 when the coil 14 is not connected, and FIG.
3 shows an output current waveform of the rectifier circuit 12 in a state where the windings 14a and 14b are connected in series. Thus, when the winding 14a and the winding 14b of the coil 14 are connected in series, the peak value of the output current of the rectifier circuit 12 becomes lower and the energizing time becomes shorter than when the coil 14 is not connected. It becomes longer and harmonic current is suppressed.

Next, when the voltage of the AC power supply 11 is a 100 volt system (115 volts in this example),
The switches 14c and 14e are closed, and the switch 14d is opened. Thereby, the windings 14a and 14b are connected to each other in parallel. The inductance of the coil 14 in this parallel connection state is equal to the inductance L of the windings 14a and 14b.

FIG. 3A shows the output voltage waveform of the AC power supply 11, FIG. 3B shows the output current waveform of the rectifier circuit 12 when the coil 14 is not connected, and FIG.
3 shows an output current waveform of the rectifier circuit 12 in a state where the windings 14a and 14b are connected in parallel. As described above, the output current of the rectifier circuit 12 is almost twice as large as that in the case of the series connection state shown in FIG.
The phase delay angle and the energizing time with respect to the output voltage of No. 1 are equal, and the harmonic current is suppressed at the same ratio as in the case of the series connection state.

As described above, when the voltage of the AC power supply 11 is 20
In the case of a 0 volt system, the windings 14a and 14b of the coil 14 are connected in series, and when the voltage of the AC power supply 11 is a 100 volt system, the windings 14a and 14b of the coil 14 are connected in parallel. As a result, the inductance of the coil 14 when the power supply voltage is 100 volts is almost twice that of the coil 14 when the power supply voltage is 200 volts. The harmonic current can be suppressed at the same rate even in a volt system.

Although the harmonic current suppressing coil is provided on the output line of the AC power supply in the first embodiment, it may be provided on the output line of the rectifier circuit. In this case, since the output current of the rectifier circuit is DC, the switch 14d in the first embodiment may be replaced with a diode 41 as shown in FIG. The output current waveform of the coil 14 in this case is the same as that shown in FIGS. 2C and 3C.

Next, a second embodiment will be described.
In this example, a coil for suppressing harmonic current is provided in the voltage doubler circuit.

FIG. 5 shows a circuit configuration. In the figure, the same components as those in FIG. 1 indicate the same components. Smoothing circuit 5
1 is composed of two capacitors 51a and 51b. The harmonic current suppressing coil 52 includes windings 52a and 52b having a common core. The windings 52a and 52b are wound such that the i terminal and the q terminal have the same polarity. Between the connection point 51c between the capacitors 51a and 51b of the smoothing circuit 51 and one output line of the AC power supply 11, a switch 52c that is selectively turned on / off according to the voltage of the AC power supply 11 is provided.

Next, the operation will be described. First, when the voltage of the AC power supply 11 is a 200 volt system (in this example, 230 volts), the switch 52c is opened. As a result, a full-wave rectified waveform is output between the + terminal and the − terminal of the rectifier circuit 12, and the charging current flows along the path indicated by the arrow. Is charged. Here windings 52a and 52b
Means that a current flows from the terminals i of the same polarity, so that they are connected in series in the same manner as in the previous embodiment, and the combined inductance L3 is obtained from Expression (1), and the number of turns of the windings 52a and 52b is N and inductance L
Then, L3 = 4L. That is, when the switch 52c is opened, the combined inductance of the coil 52 is
It is equal to four times the inductance L of 2b.

FIG. 6A shows the output voltage waveform of the AC power supply 11, FIG. 6B shows the output current waveform of the rectifier circuit 12 when the coil 52 is not connected, and FIG.
2C shows an output current waveform of the winding 52a in a state where 2c is opened. As described above, when the switch 52c of the coil 52 is opened, the peak value of the input current of the smoothing circuit 51 becomes lower and the energizing time becomes longer as compared with the case where the coil 52 is not connected, and the harmonic current is reduced. Is suppressed.

Next, when the voltage of the AC power supply 11 is a 100 volt system (115 volt in this example), the switch 52c is closed. Thereby, between the + terminal of the rectifier circuit 12 and the switch 52c and between the − terminal and the switch 52c.
Between c, it is output half-wave rectified waveform shifted in each 180 degree phase, arrows, the path the charging current flows in the. Therefore, an AC voltage is directly applied to the capacitors 51a and 51b every half cycle, so that a voltage twice the AC input voltage is charged between the + terminal of the capacitor 51a and the-terminal of the capacitor 51b. In the current path , the winding 52
Since a passes through 52b in the current path , the harmonic current suppressing effect is equivalent to a case where a coil having an inductance L is inserted in all cycles. Regarding the allowable current of the coil,
Since current flows through both a and 52b for only １ ／ cycle, the allowable current averaging one cycle is doubled, which is the same as the case where each winding in the previous embodiment is connected in parallel.

FIG. 7A shows the output voltage waveform of the AC power supply 11, and FIG. 7B shows the current waveform of the positive output line of the rectifier circuit 12 when the windings 52a and 52b are not connected. FIG. 7C shows an output current waveform of the coil 52a in a state where the switch 52c is closed. in this way,
Although the output current of the rectifier circuit 12 is almost double as compared with the case of the series connection state shown in FIG. 6C, the phase delay angle and the energizing time with respect to the output voltage of the AC power supply 11 are equal, Harmonic current is suppressed at the same rate as in the case of the series connection state.

As described above, when the voltage of the AC power
When the voltage is 0 volt, the switch 52c is opened, and when the voltage of the AC power supply 11 is 100 volt, the switch 52c is closed. As a result, the coil 52 when the power supply voltage is 100 volts has an inductance 1/4 and the allowable current is almost twice as large as the coil 52 when the power supply voltage is 200 volts. However, even with a 100 volt system, harmonic current can be suppressed at the same rate.

[0027]

According to the first aspect of the present invention, the coil is
1, composed of the second winding, by the switching means
The first and second windings are connected in parallel or in series with each other.
By selectively connecting, the inductor of the coil
And the allowable current can be selectively determined. example
If the same windings are used as the first and second windings,
If the voltage of the power supply is 200 volts,
The second windings are connected in series with each other, and the voltage of the AC power supply is 1
In the case of a 00 volt system, the first and second windings are connected in parallel with each other.
If the power supply voltage is 100 volt,
Coil when the power supply voltage is 200 volts.
The inductance is 1/4 and the allowable current is almost
Doubled, same for both 200 volt and 100 volt systems
The harmonic current can be suppressed at the same ratio. like this
In addition, the connection state of the first and second windings is changed to the switching state.
By simply switching using the
And the allowable current value for each of the two power supply voltages.
And it can be optimized. The power supply
Change to a coil with different inductance according to the voltage
Saving time and costs.

According to the second aspect of the present invention,
A series circuit between the two output lines of the rectifier circuit as a smoothing circuit
Provided two capacitors, the coil from two windings
And the above-mentioned windings are provided for the respective output lines,
In addition, a connection point between each of the capacitors is set as a switching
Selectively connect to one power line of AC power supply
It is like that. Therefore, the connection between each of the above-mentioned capacitors
By disconnecting the point from the power line,
The windings are connected to each other via two capacitors
Are connected in series with each other.
The first and second windings are connected in series with each other.
The same effect is obtained, and the connection point between each of the above capacitors
And the above-mentioned power supply line to
By alternately passing current every half cycle of force,
Allowable current can be increased by averaging the period,
In the invention of claim 1, the first and second windings are connected to each other.
The same effect as in the case of connecting in parallel is obtained. Sand
According to a second aspect of the present invention , the switch
The switching of the inductor by just switching means
And the allowable current value for each of the two power supply voltages.
And it can be optimized.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining the operation of the circuit diagram of FIG. 1;

FIG. 3 is an explanatory diagram for explaining the operation of the circuit diagram of FIG. 1;

FIG. 4 is an electric circuit diagram showing another embodiment of the present invention.

FIG. 5 is an electric circuit diagram showing a second embodiment of the present invention.

FIG. 6 is an explanatory diagram for explaining the operation of the circuit diagram of FIG. 5;

FIG. 7 is an explanatory diagram for explaining the operation of the circuit diagram of FIG. 5;

FIG. 8 is an electric circuit diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 AC power supply 12 Rectifier circuit 13 Smoothing circuit 14 Coil 14a winding 14b winding 14c switch 14d switch 14e switch 51 Smoothing circuit 52 coil 52a winding 52b winding 52c switch

Claims (2)

(57) [Claims] 1. An AC power supply, a rectifier circuit for rectifying an AC output generated from the AC power supply, a smoothing circuit for smoothing an output voltage of the rectifier circuit, an output line of the AC power supply or an output of the rectifier circuit. in the power supply circuit having a coil for harmonic current suppression provided in line, the coil has a first winding wound on a common core and a
And the first and second windings are connected in parallel with each other or in series with each other.
A switching circuit selectively connected to the power supply circuit. 2. An AC power supply, a rectifier circuit for rectifying an AC output generated from the AC power supply, and two capacitors connected in series between two output lines of the rectifier circuit. In a power supply circuit having a smoothing circuit for smoothing an output voltage, and a coil for suppressing harmonic current provided on an output line of the rectifier circuit, the coil has two windings wound around a common core. These windings are provided on each output line of the rectifier circuit, and switching means is provided between a connection point between the capacitors and one power supply line of the AC power supply. A power supply circuit which is selectively turned on / off according to a voltage of a power supply.