JP2002095257A - Power supply unit for electric apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply unit which includes a power factor improvement circuit with low noise and is capable of accommodating wide input voltage, with a simple circuit structure. SOLUTION: A choke coil for power factor improvement is formed by performing switching control, so that multiple coils provided in the power factor improvement circuit 3 may be connected in series or parallel corresponding to an inputted commercial AC voltage level. For example, when the inputted AC voltage is of 100 V system, two coils L1, L2 are connected in parallel to form the choke coil with small inductance value and large current capacity. When the AC voltage is of 200 V system, the two coils L1, L2 are connected in series to form the choke coil with large inductance value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for electronic equipment which can cope with a wide input voltage range of, for example, commercial AC voltage.

[0002]

2. Description of the Related Art A commercial power supply voltage (hereinafter referred to as "AC voltage") used worldwide can be roughly divided into an AC 100 V system and an AC 200 V system. For this reason, in an electronic device to be shipped without limiting a specific region, a power supply device corresponding to these AC 100 V system (AC 100 V to AC 120 V) voltage and AC 200 V system (AC 220 V to AC 240 V) voltage, that is, a wide input voltage is used. It is desired to be mounted.

In such a power supply device, in order to improve the power factor, for example, a so-called input choke type power factor improving circuit in which a choke coil is inserted into a rectifying and smoothing line, an active filter circuit, etc. And the like having a power factor improvement circuit constituted by

[0004]

Here, for example, in the case of the same power consumption, a case where an input choke type power factor improving circuit is formed for an AC 100 V system power supply device and a case where an input choke type power factor improvement circuit is formed for an AC 200 V system power supply device Similarly, when forming an input choke type power factor correction circuit,
The inductance values of the power factor improving choke coils used in the power factor improving circuit are different. For example, A
The choke coil used in the power factor improvement circuit of the C200V system needs an inductance value larger than that of the choke coil used in the power factor improvement circuit of the AC100V system. Further, when comparing the load current flowing through the choke coil of the AC100V power factor correction circuit with the load current flowing through the choke coil of the AC200V power factor correction circuit, the load current flowing through the choke coil of AC100V is larger. Become.

Therefore, when an input choke type power factor improving circuit is formed for an AC 100 V power supply device, it is necessary to use a choke coil having a small inductance value but a large current capacity. AC200
When an input choke type power factor improving circuit is formed for a V-system power supply device, it is necessary to use a choke coil having a large inductance but a small current capacity.

Therefore, it is difficult to form a power factor correction circuit of an input choke type in a power supply device corresponding to a wide input voltage, and the power factor is actually changed according to an AC voltage in a region where a product is used. The choke coil for improvement was changed. In other words, in the area of AC100V system, a power factor improvement circuit using a choke coil having a small inductance value and a large current capacity is mounted, and A
In the area of the C200V system, the power factor is improved by mounting a power factor improving circuit using a choke coil having a large inductance but a small current capacity.

Further, for example, an AC200
It is conceivable to provide a V-system power factor correction circuit to handle wide input voltage. However, the size of the choke coil for power factor improvement cannot be increased due to mounting surface restrictions and other factors. , The inductance value is increased by increasing the number of turns to reduce
A power factor correction circuit corresponding to the input voltage of C200V
When used at an input voltage of the C100V system, the current capacity of the choke coil becomes insufficient, and a problem such as heat generation of the choke coil may occur.

In view of the above, a power supply apparatus compatible with a wide input voltage is provided with an active filter type power factor improvement circuit which does not have the above-described problems and can easily improve the power factor. However, the active filter type power factor correction circuit has a larger number of components and costs than the above-mentioned input choke type power factor correction circuit. There is a drawback that measures such as strengthening the filter of the voltage line are required.

In view of the above, the present invention has been made in view of the above points, and has a simple configuration and a power supply device capable of coping with a wide input voltage and having a power factor correction circuit that is low in noise. The purpose is to provide.

[0010]

In order to achieve the above object, a power supply device for electronic equipment according to the present invention comprises a rectifier for rectifying and outputting an input commercial AC voltage, and a smoothing device for smoothing the rectified output of the rectifier. A rectifying / smoothing circuit comprising a capacitor, a converter circuit for converting a DC voltage obtained by the rectifying / smoothing circuit into a predetermined DC output voltage and outputting the same, and a power factor improving circuit inserted between the rectifier and the smoothing capacitor. Prepare. The power factor improving circuit includes a choke coil formed by a plurality of coils, switching means for switching a connection mode of the plurality of coils, and switching control of the switching means in accordance with an input commercial AC voltage level. Switching control means for performing the switching.

According to the present invention, a plurality of coils provided as a power factor improvement circuit are switched and controlled to be connected in series or in parallel according to the input commercial AC voltage level, thereby improving the power factor. Choke coil is formed. Thus, for example, when the first commercial AC voltage level (AC 100 V system) is set, a choke coil having a small inductance value and a large current capacity is formed by connecting two sets of coils in parallel. And a second commercial AC voltage level (AC20
(0 V system), it is possible to form a choke coil having a large inductance value by connecting two sets of coils in series.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A power supply device for an electronic device according to an embodiment of the present invention will be described below. The power supply device according to the present embodiment is mounted on an electronic device such as a monitor device, for example, and is a power supply device that can support a wide input voltage of 100 V AC and 200 V AC.

FIG. 1 is a block diagram showing a basic configuration of a power supply device according to an embodiment of the present invention. The power supply device shown in FIG. 1 includes a bridge rectifier circuit DB for rectifying a commercial AC voltage (AC voltage) from a commercial AC power supply 1, a smoothing capacitor Ci for smoothing a rectified output from the bridge rectifier circuit DB, and a smoothing capacitor Ci. A power conversion circuit 2 for converting the smoothed voltage (DC voltage) smoothed by the capacitor Ci into power and outputting the converted voltage, a bridge rectifier circuit DB and a smoothing capacitor C
i. In addition, from the commercial AC power supply 1, for example, AC100V
Any of a system AC voltage and an AC 200 V system AC voltage may be used.

Power factor improvement circuit 3 shown by a dashed line
Are two sets of coils L as choke coils for power factor improvement.
1 and L2, a switching circuit 4 for switching the connection mode of the coils L1 and L2, and a switching control circuit 5 for controlling the switching. The switching circuit 4 is composed of two sets of switching switches S1,
S2, and these changeover switches S1, S2
Are switched in conjunction with each other by the switching control circuit 5. In this case, the switching control circuit 5 controls the switching of the switches S1 and S2 of the switching circuit 4 according to the AC voltage level input from the commercial AC power supply 1. The detailed configuration of the switching control circuit 5 will be described later.

In such a power factor improving circuit 3, one end of the coil L1 is connected to the rectification output line of the bridge rectifier circuit DB and the terminal c1 of the changeover switch S1, and the other end of the coil L1 is connected to the changeover switch S2. Is connected to the terminal c2. One end of the coil L2 is connected to the terminal a1 of the changeover switch S1 and the terminal b2 of the changeover switch S2, and the other end of the coil L2 is connected to the positive electrode of the smoothing capacitor Ci and the terminal a2 of the changeover switch S2. ing.

Therefore, under the control of the switching control circuit 5,
Under the state where the changeover switches S1 and S2 are switched to the terminals a1 and a2 in conjunction with each other, the bridge rectifier circuit DB
A choke coil formed by connecting the coils L1 and L2 in parallel is inserted between the capacitor and the smoothing capacitor Ci. On the other hand, in a state where the changeover switches S1 and S2 are interlocked and switched to the terminals b1 and b2,
A choke coil formed by connecting the coils L1 and L2 in series is inserted between the bridge rectifier circuit DB and the smoothing capacitor Ci.

That is, in the present embodiment, the commercial AC power supply 1
When the AC voltage input from is set to an AC 100 V system, the switching control circuit 5 controls the switching of the switching circuit 4 so that the coils L1 and L2 are connected in parallel, so that the inductance value is small and A choke coil having a large current capacity and corresponding to an AC voltage of 100 V AC is formed. On the other hand, AC voltage is AC200V
System, the switching control circuit 5 controls the coil L
By controlling the switching of the switching circuit 4 so that L1 and L2 are connected in series, AC2 having a large inductance value,
A choke coil corresponding to the 00V AC voltage is formed. Thereby, AC100V system and AC
Power factor correction circuit 3 corresponding to wide input voltage of 200V system
Is formed.

FIG. 2 is a block diagram which embodies and shows the configuration of the power supply device shown in FIG. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the power supply device shown in FIG. 2, the smoothing capacitor Ci
Is input to the converter circuit 21 which is a power conversion circuit, and the smoothed voltage obtained by the smoothing capacitor Ci is supplied to the voltage detection circuit 6 provided in the power factor correction circuit 3. Are also branched and input. The voltage detection circuit 6 detects whether the input AC voltage is AC10 based on the smoothed voltage level of the smoothing capacitor Ci.
It detects whether the system is a 0 V system or an AC 200 V system, and outputs the detection result to the switching control circuit 5. This allows
The switching control circuit 5 controls the switching of the switching circuit 4.

In the voltage detection circuit 6 shown in FIG. 2, the input AC voltage is based on the smoothed voltage of the smoothing capacitor Ci, and the input AC voltage is 100 V AC or 200 V AC.
The system is to be detected. This is because there is a correlation between the smoothed voltage level of the smoothing capacitor Ci and the input AC voltage level. By detecting the smoothed voltage of the smoothing capacitor Ci, the input AC voltage becomes
It detects whether it is 100V system or AC200V system. The specific configuration of the voltage detection circuit 6 will also be described later.

The protection circuit 7 is provided to protect the power factor correction circuit 3 when the connection state of the coils L1 and L2 does not match the input AC voltage due to some abnormality or failure. ing. For example, the terminal voltage of the terminal b1 of the changeover switch S1 and the smoothed voltage of the smoothing capacitor Ci are input to the protection circuit 7, and the connection state of the coils L1 and L2 is detected from these terminal voltages, Input AC voltage is AC100V system or AC2
It is designed to detect whether it is a 00V system. And, for example, when the coils L1 and L2 are connected in series,
That is, the choke coil of the power factor correction circuit 3 is AC200
Under the condition corresponding to V system, AC100V
When the system AC voltage is input, the operation of the converter circuit 21 is shut down. Thus, the power factor correction circuit 3 is protected.

As will be described later, the converter circuit 21
By performing switching of the input smoothed voltage, the DC-DC converter converts the DC voltage to a predetermined level DC voltage and outputs the DC voltage.

FIG. 3 shows a specific circuit configuration of the power supply device shown in FIG. The same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the power supply device shown in FIG. 3, first, as a rectifier circuit for rectifying an input from the commercial AC power supply 1 to a commercial AC voltage, a bridge rectifier circuit DB in which four diode elements are bridge-connected, and a bridge rectifier circuit DB A smoothing capacitor Ci for smoothing the rectified output is provided. A power factor improvement circuit 3 surrounded by a broken line is inserted between the bridge rectifier circuit DB and the smoothing capacitor Ci.

As described above, the power factor improving circuit 3 is provided with two sets of coils L1 and L2. In this case, the coils L1 and L2 can be formed separately from each other, or the coils L1 and L2 can be wound around one core. One end of the coil L1 is connected to the rectification output line of the bridge rectifier circuit DB and, for example, the terminal c1 of the changeover switch S1 of the electromagnetic relay circuit 4a, and the other end is connected to the terminal c2 of the changeover switch S2 of the electromagnetic relay circuit 4a. Connected to The coil L2 has one end connected to the terminal a1 of the changeover switch S1 and the terminal b2 of the changeover switch S2, and the other end connected to the positive electrode of the smoothing capacitor Ci and the terminal a2 of the changeover switch S2. ing. Thus, the rectified output of the bridge rectifier circuit DB is equal to the coil L1,
The smoothing voltage is input to the smoothing capacitor Ci via a choke coil formed by connecting L2 in parallel or in series, and the smoothed voltage is supplied to the converter circuit 21 by the smoothing capacitor Ci.

The smoothing voltage of the smoothing capacitor Ci is:
As described above, since there is a correlation with the input AC voltage level, the AC voltage level is detected from the smoothed voltage. Here, the smoothed voltage of the smoothing capacitor Ci is divided by the resistors R1 and R2, and the divided voltage is
For example, an input AC voltage is detected by comparing the voltage Vcc with a reference voltage divided by resistors R3, R4 and R5 by a comparator U1 having an open collector or open drain type internal configuration. .
Therefore, in the comparator U1, the above-described reference voltage is applied to the positive-phase input terminal (+), and a divided voltage obtained by dividing the smoothed voltage is applied to the negative-phase input terminal (-).
Therefore, the output of the comparator U1 is at the "Low" level (0 level) when the input AC voltage is the AC 200V system, and is at the "High" level when the input AC voltage is the AC 100V system. Here, the comparator U1 is connected to resistors R3, R4, R5 as shown in the figure to provide hysteresis characteristics, thereby obtaining stability at the time of switching.

In this case, since the "High" output of the comparator U1 is set to a low level by the voltage division of the resistors R3, R4, R5, it is input to the negative phase input terminal of the comparator U2 which is a level converter. The level conversion (amplification) is performed by comparing with the threshold voltage Vr input to the positive-phase input terminal.

The output of the comparator U2 is input to the base of the switching device Q1. Switching element Q1
Is a drive circuit for driving the electromagnetic relay circuit 4a, and switches the switches S1 and S2 provided in the electromagnetic relay circuit 4a in conjunction with each other based on the output of the comparator U2. In this case, the switching element Q1 is turned off when the input voltage is 100V AC and turned on when the input voltage is 200V. When the changeover switches S1 and S2 of the electromagnetic relay circuit 4a are 100V AC, the switching element Q1 is connected to the terminals a1 and a2. In the case of a 200 V AC system, it is connected to the terminals b1 and b2. That is, AC1
In case of 00 system, parallel connection of coil L1 and L2, AC200V
In the case of the system, the switching control is performed so as to be formed by the series connection of the coils L1 and L2.

The protection circuit 7 detects the connection state of the coils L1 and L2 and the input AC voltage level, so that when the AC voltage of 100V AC, which is considered to have a large load current, is input, Due to some trouble, the coils L1 and L2 are connected to the AC 200V system,
It is provided to prevent the coils L1, L2 from being heated by heat even when a choke coil is formed by the serial connection of 1, 1 and L2.

The configuration of the protection circuit 7 shown in FIG. 3 includes resistors R7, R8, R9 for dividing the smoothed voltage of the smoothing capacitor Ci, and a switching element Q2.
The voltage Vd divided by the resistors R7 and R8 is applied to the resistor R9.
And input to the operation control unit 40 of the converter circuit 21 as a detection voltage. The base of the switching element Q2 is connected to the terminal b1 of the changeover switch S1 via a base current limiting resistor R10. In addition,
Its emitter is grounded.

In the protection circuit 7 having such a configuration,
For example, during normal operation in which the input voltage is set to an AC 100 V system and the changeover switches S1 and S2 of the electromagnetic relay circuit 4a are connected to the terminals a1 and a2, the switching element Q2 is turned off. The voltage (Vd1) obtained by dividing the smoothed voltage corresponding to the input voltage of the AC 100 V system by the resistors R7 and R8 is input to the unit 40 as the detection voltage. Further, for example, when the input voltage is AC200
And a changeover switch S1 of the electromagnetic relay circuit 4a.
During the normal operation in which S2 is connected to the terminals b1 and b2, the switching element Q2 is turned on. Therefore, the operation control unit 40 of the converter circuit 21 supplies a smoothed voltage corresponding to the input voltage of the AC 200 V system to the operation control unit 40. Resistance R7 and resistance R8, R
The voltage (Vd2) divided by the combined resistor of No. 9 is input as the detection voltage.

On the other hand, for example, in the event of an abnormal operation in which the changeover switches S1 and S2 of the electromagnetic relay circuit 4a are connected to the terminals b1 and b2 despite the input voltage of the AC 100 V system, the switching element Q2 is turned on. Therefore, the operation control unit 40 of the converter circuit 21 supplies the smoothed voltage corresponding to the input voltage of the AC 100 V system to the resistor R7 and the resistors R8 and R9.
The voltage (Vd3) divided by the combined resistance is input as the detection voltage.

In this case, regardless of the resistance value of the resistors R7 to R9, for example, regardless of the 100 V system or the 200 V system, the detection voltage (V
d1, Vd2) is equal to or higher than a certain threshold voltage (Vop) and the changeover switch S of the electromagnetic relay circuit 4a despite the fact that at least 100 V AC voltage is input.
During an abnormal operation where the terminals S1 and S2 are connected to the terminals b1 and b2, the detection voltage (Vd
A resistance value that makes 3) below a certain threshold voltage Vop is appropriately selected.

Therefore, the protection circuit 7 having such a configuration is provided, and the detection voltage Vd output from the protection circuit 7 is provided.
The operation control unit 40 of the converter circuit 21
If the operation of the converter circuit 21 is controlled, the coils L1 and L2 provided in the power factor correction circuit 3 can be protected from problems such as heat generation.

Here, as an example of the converter circuit 21 shown in FIG. 3, the configuration of a switching converter circuit is shown in FIG. The switching converter circuit shown in FIG. 5 is constituted by one switching element Q11, and the smoothed voltage of the smoothing capacitor Ci shown in FIG. 3 is input from the input terminal t1 as the input voltage Vin.
This input voltage Vin is supplied to the collector of the switching element Q11 via the primary winding N1 of the insulating converter transformer SRT. When the switching element Q11 performs the switching operation, an alternating voltage is induced in the secondary winding N2 provided on the secondary side of the insulating converter transformer SRT, and this alternating voltage is rectified by the rectifying diode D11 and the smoothing capacitor C11. A predetermined secondary-side output voltage Vout is obtained by performing rectification and smoothing by a smoothing circuit.

The switching operation of the switching element Q11 is controlled by the operation control section 40. The operation control unit 40 includes a switching element Q1 with a PWM (Pulse Width Modul).
ation) An oscillation circuit 42, an oscillation control circuit 41, and a PWM control circuit 43 for operating in a control method are provided. In this case, the detection voltage Vd from the protection circuit 7 shown in FIG. 3 is input to the PWM control circuit 43 via the operation control terminal t2.
Means that the voltage level of the detection voltage Vd is a certain threshold voltage Vop
In the following cases, the operation is forcibly stopped.

The PWM control circuit 43 supplies a secondary output voltage via the constant voltage control unit 30 to make the secondary output voltage Vout output from the secondary side of the insulating converter transformer SRT constant. Has been fed back. The constant voltage control unit 30 includes a voltage detection circuit 31 for detecting a secondary-side output voltage level, a reference voltage circuit 32 for generating a predetermined reference voltage, and a detection voltage and a reference voltage detected by the voltage detection circuit 31. And outputs an error signal corresponding to the secondary-side output voltage level to the PWM control circuit 43. In addition,
The configuration of the converter circuit shown in FIG. 5 is merely an example, and converter circuit 21 of the present invention is not limited to such a configuration.

FIG. 4 is a diagram showing a specific circuit configuration of a power supply device according to a second embodiment of the present invention. Also in this case, the same parts as those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted. The power factor correction circuit 3 of the power supply device shown in FIG.
It is configured so that the connection form of 1 and L2 can be set manually. For this reason, the power factor improving circuit 3 is provided with a changeover switch S3.
By switching the changeover switch S3 to the terminal a3 side, the switching element Q1 is turned on and the AC 100
In the case of the V system, the switching element Q1 is turned off by switching the changeover switch S3 to the terminal b3 side.

In the present embodiment described above, the smoothing voltage obtained by the smoothing capacitor Ci is
The on / off control of the switching element Q2 provided in the protection circuit 7 is only an example.
For example, it is also possible to configure a protection circuit by detecting the temperatures and currents of the coils L1 and L2.

In the present embodiment, the power factor improving circuit 3
Are provided with two sets of coils L1 and L2.
Although a case where a choke coil is formed by connecting 1, L2 in series or in parallel is shown, a plurality of coils are further provided in the power factor correction circuit 3 and these coils are connected in series or in parallel. , AC100V system or AC200
It is of course possible to form a choke coil for power factor improvement corresponding to the V-system input voltage.

[0039]

As described above, in the power supply device for electronic equipment according to the present invention, a plurality of coils provided as choke coils in the power factor correction circuit are connected in series in accordance with the input commercial AC voltage level. Or, by performing switching control so as to be connected in parallel, a choke coil for power factor improvement is formed. For example, when the input commercial AC voltage is set to the first voltage level (AC100V system),
By connecting two sets of coils in parallel, a choke coil having a small inductance value and a large current capacity is formed, and a second commercial AC voltage level (AC
(200 V system), a choke coil having a large inductance value is formed by connecting two sets of coils in series. With this, AC100V
It is possible to form a power factor improvement circuit that can cope with both the AC system and the commercial AC voltage of the AC 200 V system with a simple circuit using a choke coil and at a low cost.

If the choke coil formed by the serial connection or the parallel connection of the plurality of coils is not appropriate based on the detection result of the detecting means for detecting the connection state of the plurality of coils, the operation of the converter circuit is stopped. Therefore, the power factor correction circuit can be protected.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a power supply device according to an embodiment of the present invention.

FIG. 2 is a block diagram embodying and showing the configuration of the power supply device shown in FIG.

FIG. 3 is a diagram showing a specific circuit configuration of the power supply device shown in FIG. 2;

FIG. 4 is a diagram illustrating a specific circuit configuration of a power supply device according to a second embodiment.

FIG. 5 is a diagram illustrating an example of a converter circuit.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 commercial AC power supply, 2 power conversion circuit, 3 power factor improvement circuit, 4 a relay circuit, 4 switching circuit, 5 switching control circuit, 6 voltage detection circuit, 7 protection circuit, 21 converter circuit, 30 constant voltage control unit, 31 voltage Detection circuit, 32
Reference voltage circuit, 33 error amplifier circuit, 40 operation control section, 41 oscillation control circuit, 42 oscillation circuit, 43 control circuit a1 to a3 b1 to b3 c1 to c3 terminals, t1 input terminal, t2 operation control terminal, t3 output terminal, Ci C11
Smoothing capacitor, D11 rectifier diode, DB bridge rectifier circuit, L1 L2 coil, N1 primary winding, N2
Secondary winding, SRT isolated converter transformer, Q1 Q2
Q11 switching element, R1-R10 resistance, S1-S
3 selector switch, U1 U2 comparator

Claims (5)

[Claims] 1. A rectifier for rectifying and outputting an input commercial AC voltage, a rectifying / smoothing circuit comprising a smoothing capacitor for smoothing the rectified output of the rectifier, and a DC voltage obtained by the rectifying / smoothing circuit, A converter circuit for converting the output into a DC output voltage and outputting the output; and a power factor improvement circuit inserted between the rectifier and the smoothing capacitor, wherein the power factor improvement circuit is a choke coil formed by a plurality of coils. Electronic equipment, comprising: switching means for switching the connection mode of the plurality of coils; and switching control means for performing switching control of the switching means in accordance with an input commercial AC voltage level. Power supply. 2. The switching control means controls the plurality of coils to be connected in parallel by the switching means when the input commercial AC voltage is at the first voltage level. 2. The power supply device for an electronic device according to claim 1, wherein when the commercial AC voltage is set to the second voltage level, the switching means controls the plurality of coils to be connected in series. 3. The power supply device for an electronic device according to claim 1, wherein said switching control means performs switching control of said switching means based on a DC voltage level obtained from said smoothing capacitor. 4. The power supply device for an electronic device according to claim 1, wherein said switching means comprises an electromagnetic relay circuit. 5. The apparatus according to claim 1, further comprising: detecting means for detecting a connection state of the plurality of coils, wherein the operation of the converter circuit is stopped based on a detection result of the detecting means. A power supply device for the electronic apparatus according to the item.