JPH10271812A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply capable of performing a stable operation over the wide range of the voltages of a power source. SOLUTION: A power supply is provided with detecting means 1, 12 to 15, which detect the voltage of an AC power supply, a current detecting means 10 which outputs a voltage corresponding to an input current value, a correcting means 11, which adjusts the output voltage value of the current detecting means 10 based on the outputs of the detecting means 1, 12 to 15, and a control means 9 which controls the power factors, etc., of the power supply based on the output voltage of the correcting means 11. This correcting means 11 is made up of a multiplier which multiplies the effective value of the input AC voltage by the output value from the current detecting means 10, a voltage range determining means, a switching means and an attenuating means. This structure makes it possible to maintain the signal level to be inputted into the control means 9 at a given value or more, which improves the signal-to-noise ratio and stabilize the operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply, and more particularly, to a power supply capable of stably operating in a wide input voltage range in an AC-DC converter having a power factor improving function.

[0002]

2. Description of the Related Art Hitherto, a boost type AC / DC converter has been used to improve a power factor. This boost-type converter circuit rectifies an AC input, converts the rectified AC input into a high-voltage DC by a choke-input type booster chopper circuit, and then converts it into a DC current of a desired voltage by a DC / DC converter. . The choke input type boost chopper circuit keeps the output voltage constant, controls the input current waveform to be similar to the input voltage waveform, and has a power factor higher than that of a capacitor input type rectifier circuit. Is greatly improved.

FIG. 3 is a circuit diagram showing an example of a choke input type booster circuit used in a conventional boost type AC / DC converter circuit. The alternating current (AC) input is full-wave rectified by the diode bridge 1 to form a pulsating flow. FET
4 is pulse-driven by a converter IC 9 having a power factor improving function. When FET4 is on, inductor 3
When the FET 4 is turned off, the energy is released, and a high voltage is generated at the connection point between the inductor 3 and the FET 4. The high voltage is rectified by the diode 5 and accumulated and smoothed by the capacitor 6. The capacitor 2 is, for example, a capacitor for preventing noise of about 0.47 μF and has no smoothing action.

The resistor 10 is a resistor for detecting a current of, for example, about several hundred milliohms. A signal obtained by dividing the output voltage of the power supply circuit by the resistors 7 and 8 is supplied to the VIN terminal of the power factor improving converter IC 9, and the pulsating voltage obtained by full-wave rectification is supplied to the resistor 1.
The signal divided by 2 and 13 is input to the V DET terminal, and the voltage signal corresponding to the input current value is input to the I DET terminal. The voltage generated by the resistor 10 is a voltage more negative than GND.

FIG. 4 is a block diagram showing an example of the internal configuration of the power factor correction converter IC 9. The voltage error amplifier 30 outputs a voltage error signal corresponding to the difference between the VIN signal obtained by dividing the output voltage of the power supply circuit and the reference voltage,
Multiplies the error voltage by the input pulsating voltage waveform signal V DET. The current error amplifier 32 outputs a signal corresponding to an error between the current waveform IDET detected by the resistor 10 and the output voltage waveform of the multiplier 31. The oscillator 33 generates, for example, a sawtooth wave of several tens of kilohertz,
4 is the output sawtooth wave of the oscillator 33 and the current error amplifier 3
2 and outputs a drive signal pulse for FET4.

This circuit keeps the output voltage constant, and also has an input voltage waveform (V DET) and an input current waveform (I DE
And T) act in a similar waveform having the same phase. Therefore, the power factor can be made approximately one. A power factor improving converter IC having such a function is commercially available.

[0007]

At present, power supply voltages in various countries are various, for example, from 100 V to 220 V, and electronic equipment is required to have a worldwide function that can be used at an arbitrary power supply voltage. The voltage range needs to correspond to about 85 V to 260 V in consideration of fluctuations. On the other hand, the operable voltage range at the input terminal of the power factor correction converter IC is limited, and it is necessary to design a circuit so as not to exceed this limit. For example, the input voltage range is 85 V to 260 V, the maximum power is 1 KW, and the maximum input voltage at which the IDET terminal of the converter IC can operate is 1 V (the actually input voltage is negative,
Assuming that the absolute value is 1 V), the maximum current flows through the resistor 10 in FIG. 3 when the load is 1 KW and the input voltage is the lowest 85 V. Therefore, in order to prevent a voltage of 1 V or more from being applied to the converter IC at this time, the value of the resistor 10 needs to be 85 mOhm or less. (Note that the value of the resistor 10 is not 1 / √2 or less in order to prevent the voltage from exceeding the effective value of the power supply voltage and 1 V at the peak. In consideration of the power loss in the power supply circuit, These values are further reduced, but are not taken into account in the description to simplify the calculation.) FIG.
9 is a graph showing a current detection signal level with respect to a power supply input voltage at the time of 10 outputs. The value of the resistor 10 is determined as described above.
When used at 00 W, the input current is inversely proportional to the input voltage and proportional to the output power. Therefore, as shown in FIG.
The voltage generated by the resistor 10 is 1 V × (85/26
0) × (1/10) = 0.033 V, and the signal level becomes a very small value.

On the other hand, the output voltage of the power supply circuit shown in FIG. 3 needs to be equal to or higher than the peak value of the input voltage.
It is necessary to set the voltage to V or more, and it is necessary to control on / off of this high voltage current by FET4. Therefore, there is a problem that a large noise signal accompanying the switching gets on the converter IC, the signal-to-noise ratio decreases, and the operation becomes unstable. Further, when the power supply device has a dual configuration or the like in order to improve reliability, the output power of one power supply circuit becomes smaller than that of the other power supply if there is no output current balance circuit between the two power supplies. There is also a problem that it becomes more remarkable. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a power supply device capable of operating stably over a wide range of power supply voltages.

[0009]

A power supply device according to the present invention includes a power supply voltage detecting means for detecting an AC power supply voltage, a current detecting means for outputting a voltage corresponding to an input current value, and an output voltage of the power supply voltage detecting means. It is characterized by comprising correction means for correcting the output voltage value of the current detection means based on the value, and control means for controlling the power supply based on the output voltage of the correction means.

According to the present invention, the correction means includes a multiplier for multiplying the effective value of the input AC voltage by the output value from the current detection means, or whether the AC power supply voltage is equal to or lower than a predetermined value. By providing an attenuator capable of controlling whether the output value from the current detection means is attenuated or passed as it is, the level of the signal input to the control means is set to be equal to or less than the maximum inputtable value and equal to or more than a predetermined value. Acts to keep.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit diagram showing a configuration of a first embodiment of a power supply device to which the present invention is applied. This circuit is used, for example, as a choke input type booster circuit in the boost type AC / DC converter circuit described above with reference to the conventional example. The AC power supply input voltage range is, for example, 8
It produces a DC output of 400V from 5V to 260V. The same elements as those of the conventional booster circuit shown in FIG. 3 are denoted by the same reference numerals.

The difference from the conventional circuit is that a value of a resistor 10 for current detection and a multiplier 11 are provided. The resistor 10 for current detection is, for example, when the input power supply voltage is the highest at the maximum load and the current value is the lowest,
The voltage generated by the resistor 10 is the power factor improving converter I.
It is set so as to be the maximum operable voltage of the IDET terminal which is the current value input terminal of C9. For example, when the input maximum voltage is 260 V, the output power is 1 KW, and the operable maximum voltage of the IDET terminal is 1 V, the value of the resistor 10 is set to 260 mOhm. In this case, if the power supply voltage is 260 V, the voltage generated by the resistor 10 is 1 V, and if the power supply voltage is 85 V, a voltage of about 3 V is generated.

The multiplier 11 is, for example, a known transconductance multiplier or an analog multiplier using a logarithmic amplifier. A DC voltage (indicating the effective value of the AC input voltage) obtained by dividing the full-wave rectified pulsating current by the resistors 12 and 13 and smoothing it by the resistor 14 and the capacitor 15 is input to the VIN terminal of the multiplier 11. Yes,
A voltage signal generated by the resistor 10 is input to the IIN terminal. The output OUT of the multiplier 11 is connected to the IDET terminal of the converter IC9.

The multiplier 11 outputs OUT = (IIN) × (VI
The coefficient is set so as to be N) / 260. For example, when the power supply voltage is 260 V, the IIN signal is output as it is, and when it is 85 V, a value of approximately (IIN) / 3 is output. With such a circuit configuration, if the output power is constant, the product of the input voltage (VIN) and the input current (IIN) is constant, so that even if the input voltage of the power supply changes, the multiplier 1
1 is constant. The OUT signal fluctuates only depending on the magnitude of the load, and 1 V is output at the maximum load.

FIGS. 6 and 7 are graphs showing the current detection signal level with respect to the power supply input voltage at rated output and at 1/10 output in the embodiment of the present invention. In the first embodiment, at the time of rated (maximum) output, the level of the current detection signal input to the converter IC 9 is 1 V regardless of the value of the input voltage. Also, at the time of 1/10 output, the voltage is also 0.1 V regardless of the value of the input voltage. Therefore, even when the power supply voltage is high and the input current is small, the current detection signal at a higher level than in the prior art is input to the converter IC 9, so that the signal-to-noise ratio is improved and the operation becomes more stable.

FIG. 2 shows a second embodiment of the power supply device to which the present invention is applied.
FIG. 2 is a circuit diagram illustrating a configuration of an example. This circuit is also used as a choke input type booster circuit in a boost type AC / DC converter circuit, and has an AC power supply input voltage range of, for example, 85V to 260V, and generates a DC output of 400V. The same elements as those of the booster circuit shown in FIGS. At present, power supply voltages in the world are roughly divided into a 100V zone and a 220V zone. Therefore, instead of continuously adjusting the current detection signal based on the power supply voltage value as in the first embodiment, whether the current detection signal is 100 V or 220 V is detected. This is to lower the level.

The second embodiment differs from the conventional circuit in that the value of the current detecting resistor 10 and the comparator 20,
It is provided with a switching circuit 22 and attenuation circuits 23 and 24. For example, when the input power supply voltage is the lowest voltage in the 220 V range at the time of the maximum load, the voltage generated by the resistance 10 is an IDET terminal which is a current value input terminal of the power factor correction converter IC9. Is set to be the maximum operable voltage. For example,
Input minimum voltage 185V, output power 1 in 220V zone
When the maximum operable voltage of the KW and IDET terminals is 1 V, the value of the resistor 10 is set to 185 mOhm. In this case, when the power supply voltage is 185 V, the voltage generated by the resistor 10 becomes 1 V.

The + input terminal of the comparator 20 is connected to a reference voltage generating circuit comprising a resistor 25 and a Zener diode 26, and the-terminal is connected to a smoothing circuit comprising a resistor 14 and a capacitor 15. Comparator 20
Is 0 when the power supply voltage (effective value) is 185 V or more.
The voltage value of the Zener diode is set so that V is output, and when it is less than 185 V, the voltage of the low-voltage power supply Vcc (not shown) is output.

The resistor 21 and the transistor 22 form a switching circuit. When the transistor 22 is off, that is, when the power supply voltage is 185 V or higher, the input impedance of the IDET terminal is high. Disappears, and the current detection signal generated by the resistor 10 is directly input to the IDET terminal. When the transistor 22 is on, that is, when the power supply voltage is lower than 185 V, the current detection signal is divided by the resistors 23 and 24, and the attenuated signal is input to the IDET terminal.

When the input voltage is the lowest voltage in the 100V area, for example, 85V at the maximum load,
The voltage applied to the DET terminal is set so as not to exceed 1V. For example, if the resistance 10 is 185 milliohm and the input voltage is 8
If the signal is not attenuated at 5 V, the voltage applied to the IDET terminal is about 2.2 V, so the attenuation factor is set to 1 / 2.2.

In the graphs of the second embodiment shown in FIGS. 6 and 7, when the judgment threshold value of the comparator 20 is 185 V, 185
In the voltage range of less than V, the voltage level is the same as that of the conventional example.
The signal-to-noise ratio is improved and operation becomes more stable.

Although the embodiment has been disclosed above, the present invention may be modified as follows. In the second embodiment, an example in which the voltage is divided into two ranges of 100V and 220V is disclosed. However, even if the voltage range is divided into three or more, the technology of the second embodiment can be applied as it is. Also, the judgment level of the voltage range does not need to be the lowest value on the high voltage side,
Any value can be selected as long as it is between the value and the maximum value on the low pressure side.

[0023]

As described above, in the present invention,
The correction means includes a multiplier for multiplying the effective value of the input AC voltage and the output value from the current detection means, or determines whether the output value from the current detection means depends on whether the AC power supply voltage is equal to or less than a predetermined value. By providing an attenuator capable of controlling whether the signal is attenuated or passed as it is, the signal is supplied to the control means so that the level of the signal detected by the current detection means does not decrease in an arbitrary power supply voltage range. Accordingly, there is an effect that the signal-to-noise ratio does not decrease and the operation of the power supply device is stabilized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a first embodiment of a power supply device of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a second embodiment of the power supply device of the present invention.

FIG. 3 is a circuit diagram showing an example of a conventional choke input type booster circuit.

FIG. 4 is a block diagram showing an example of the internal configuration of a power factor correction converter IC.

FIG. 5 is a graph showing a current detection signal level with respect to a conventional power supply input voltage.

FIG. 6 is a graph showing a current detection signal level with respect to a power supply input voltage at a rated output.

FIG. 7 is a graph showing a current detection signal level with respect to a power supply input voltage at the time of 1/10 output.

[Explanation of symbols]

1 ... diode bridge, 2, 6, 15 ... capacitor,
3 ... Inductor, 4 ... FET, 5 ... Diode, 7,
8, 10, 12, 13, 14, 21, 23, 24, 25
... Resistor, 9 ... Power factor improvement converter IC, 11 ... Multiplier,
Reference numeral 20: comparator, 22: transistor, 26: zener diode

Claims (5)

[Claims] A power supply voltage detecting means for detecting an AC power supply voltage; a current detecting means for outputting a voltage corresponding to an input current value; and an output voltage of the current detecting means based on an output voltage value of the power supply voltage detecting means. A power supply device comprising: a correction unit that corrects a value; and a control unit that controls a power supply based on an output voltage of the correction unit. 2. The power supply voltage detection means is an effective value detection means for outputting a voltage corresponding to an effective value of an AC power supply voltage, and the correction means is provided with an output voltage value of the effective value detection means and the current detection. 2. The power supply device according to claim 1, wherein the power supply device is a multiplication unit that multiplies an output voltage value of the unit. 3. The control means is a power factor improvement control circuit. The resistance value of the current detection means is such that the voltage generated by the resistance when the input power supply voltage is the maximum at the maximum load is the power factor improvement control circuit. The multiplication coefficient of the multiplier is set so that the output value of the current detection means is output as it is when the input power supply voltage is the highest. The power supply device according to claim 2, wherein: 4. The power supply voltage detecting means is a voltage determining means for outputting a signal indicating whether or not the effective value of the AC power supply voltage is equal to or higher than a predetermined determination voltage. Based on the output signal of, when the effective value of the power supply voltage is equal to or more than a predetermined determination voltage, the output voltage value of the current detection means is output as it is,
2. The power supply device according to claim 1, wherein the power supply device is an attenuating unit that attenuates and outputs an output voltage value of the current detecting unit when an effective value of the power supply voltage is less than a predetermined determination voltage. 5. The control means is a power factor improvement control circuit, and a resistance value of the current detection means is generated by the resistance when an input power supply voltage is the predetermined determination voltage at a maximum load. The voltage is set so as to be the maximum voltage at which the input terminal of the power factor improvement control circuit can operate, and the attenuation rate of the attenuating means at the maximum load is the output of the attenuating means even if the input power supply voltage is the lowest value. The power supply device according to claim 4, wherein the voltage is adjusted so as to be equal to or less than a maximum voltage that can be input to the power factor improvement control circuit.