JP4674122B2 - Power supply - Google Patents

Description

  The present invention relates to a power supply apparatus, and more particularly to a technique for reducing harmonic noise.

  In recent years, the regulation of harmonic noise emitted from power supply devices has become stricter, and in conventional AC / DC adapters, the power factor, which is the ratio of active power to apparent power, is improved (closer to 1) in the power supply circuit. Some have a (power factor improvement circuit) that can reduce the noise of the DC output to a considerable extent.

Patent Document 1 describes a technique related to active PFC, which is one example of PFC.
JP 2003-125582 A

  By the way, in recent years, the regulation of harmonic noise has become stricter, and there is a case where it is required to further reduce the harmonic noise than the noise reduction effect that can be realized by the conventional AC / DC adapter. In such a case, it may be possible to further strengthen the PFC of the conventional AC / DC adapter, but there is a problem that the number of parts increases.

  The present invention has been made in view of the above problems, and one of its purposes is a power supply apparatus that can reduce harmonic noise generated in the DC output of the AC / DC adapter and can be realized with as few parts as possible. Is to provide.

  A power supply device according to the present invention for solving the above-described problems is output from the rectifying element by switching according to a predetermined control with a rectifying element that limits polarity inversion of the DC output from the AC / DC adapter. Input feedback noise generated by switching of the first switch element, the first switch element for converting the voltage of the DC output, and being branched between the rectifier element and the first switch element. In the power supply device including the capacitor element for reducing the impedance, an inductor element is inserted between the AC / DC adapter and the rectifier element.

  Some power supply apparatuses include a switching DC / DC converter that can further convert a voltage output from an AC / DC adapter by predetermined control to obtain an arbitrary DC output voltage. This switching DC / DC converter includes a switching element (such as a transistor or a MOSFET) that switches in accordance with the above control. In a normal DC / DC converter, the voltage is reduced by inserting a resistor, whereas in a switching DC / DC converter, the switching element is periodically turned on and off to periodically turn on and off the voltage output period. To substantially reduce the voltage.

  However, when this switch element switches, noise called input feedback noise is generated. The switching DC / DC converter also includes a capacitive element for absorbing this input feedback noise. This capacitive element is provided in front of the switch element (input side).

  Moreover, although the polarity of the DC output from the AC / DC adapter may be inverted, the power supply device is provided with a diode (rectifier element) for preventing the polarity inversion.

  According to the above configuration, the passive rectifier and the input capacitor provided in the power supply device are also used as the passive rectifier and capacitor of the passive PFC, thereby realizing the passive PFC only by inserting the inductor element. A passive PFC is a PFC consisting only of passive elements. For this reason, it is possible to further reduce harmonic noise generated at the output of the AC / DC adapter, and to suppress an increase in the number of parts due to insertion of a passive PFC.

  In the power supply apparatus, the AC / DC adapter includes a second switch element for converting a voltage, and at least one of a capacitor capacity of the capacitor element and an inductance capacity of the inductor element is the first switch element. It is good also as having been determined based on the control period of 2 switch elements.

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

  FIG. 1 is a circuit configuration diagram of a power supply device 1 according to an embodiment of the present invention. As shown in the figure, the power supply apparatus 1 includes an AC main 5, an AC / DC adapter 10, a filter 6, a passive PFC 20, and a DC-DC converter 30.

  The power supply apparatus 1 is used as a power supply for various information processing apparatuses, for example. Specifically, a DC electrical signal output from the power supply device 1 is input to the information processing device, and the information processing device is driven using the input electrical signal as a power source. Note that the voltage required by the information processing device for this electrical signal that is used as a drive power source by the information processing device differs for each information processing device. In response to this, in the power supply device 1, the output voltage control for each information processing device is performed in the DC-DC converter 30. Details will be described later.

  The AC main 5 is a so-called commercial AC power supply, and outputs an AC electrical signal to the AC / DC adapter 10. The frequency of the AC electrical signal output at this time is ideally a rated frequency (for example, 50 Hz), but actually includes a frequency fluctuation component and a noise component.

  The AC / DC adapter 10 includes a filter 11, a rectifier 12, a filter 13, an active PFC (A-PFC) 14, and a DC-DC converter (DCDC-C) 15. The electric signal is converted into a DC electric signal and output as a DC output.

  The filter 11 is connected to the AC main 5 and receives the electric signal input from the AC main 5. The filter 11 is a band-pass filter, for example, which cuts off frequency components other than the set frequency (for example, 50 Hz for a 50 Hz alternating current) included in the input electrical signal, and only sets the set frequency component. Take out and output to the rectifier 12.

  The rectifier 12 is, for example, a diode bridge, and converts the AC electrical signal input from the filter 11 into a DC electrical signal by full-wave rectification and outputs the DC electrical signal to the filter 13. However, the DC electric signal output at this time includes an AC noise component.

  The filter 13 is a low-pass filter, for example. The filter 13 reduces the noise component by blocking the AC noise component included in the DC electric signal input from the rectifier 12 and acquires a low noise DC electric signal. The filter 13 outputs the acquired DC electric signal to the A-PFC 14.

  The active PFC 14 improves the power factor (ratio of active power and apparent power) of the input DC electric signal (closes to 1). Apparent power is the power that flows through the electrical line, and active power is the power that is actually consumed in the load. For this reason, the closer the active power is to the apparent power, the better the electricity utilization efficiency. Further, when the power factor is low, the current waveform of the circuit becomes a pulse shape. This means the generation of harmonic noise. Therefore, the AC / DC adapter 10 reduces the harmonic noise by improving the power factor with the active PFC 14. The active PFC 14 outputs a DC electric signal with reduced harmonic noise to the DC-DC converter 15 in this way.

  The DC-DC converter 15 converts the voltage of the DC electric signal output from the active PFC 14 into a predetermined voltage. This predetermined voltage is a voltage determined as an output voltage of the AC / DC adapter 10. The output of the DC-DC converter 15 becomes the DC output of the AC / DC adapter 10 and is output to the filter 6. The DC electrical signal output at this time includes AC noise components including harmonic noise components that cannot be ignored in recent regulations, although they are considerably reduced by the active PFC 14. In addition, the DC-DC converter 15 may include a switching element as in the DC-DC converter 30 described later. In this case, harmonic noise (more specifically, this switching element) Harmonic noise having a period equal to the switching period of the switch element is also generated.

  Note that a DC-DC converter 30 whose switching cycle is described in terms of frequency and is approximately 50 kHz to 520 kHz is generally used. Since the frequency of the AC main 5 is 50 Hz in eastern Japan, the switching cycle of the switch element included in the DC-DC converter 15 is approximately 1/1000 to 1/10000 compared to the AC main 5. For this reason, harmonic noise having a period of 1/1000 to 1/10000 as compared with the period of the AC main 5 is generated.

  The filter 6 is a low-pass filter, for example. This filter 6 reduces the noise component by blocking the AC noise component contained in the DC electric signal input from the AC / DC adapter 10 and acquires a low noise DC electric signal. The filter 6 outputs the acquired DC electric signal to the passive PFC 20.

  The passive PFC 20 is a PFC that includes an inductor element 21, a rectifying element 22, and a capacitive element 31. The inductor element 21, the rectifying element 22, and the capacitive element 31 are all passive elements, and the passive PFC 20 is a PFC composed of only passive elements.

  The inductor element 21 is an inductor with an iron core, for example. The rectifying element 22 is, for example, a diode, and limits the polarity inversion of the electric signal. The capacitive element 31 is, for example, a capacitor, and is arranged to branch to the subsequent stage of the rectifying element 22.

  The passive PFC 20 uses these three elements to improve the power factor of the input electric signal. Although this point is the same as the active PFC 14, the passive PFC 20 is composed of only passive elements, and therefore is different from the active PFC 14 in that the number of parts is small.

  The passive PFC 20 improves the power factor of the input electric signal, and as a result, further reduces harmonic noise components contained in the DC electric signal input from the AC / DC adapter 10. Then, the passive PFC 20 outputs a DC electric signal with reduced harmonic noise components to the DC-DC converter 30.

  When the DC-DC converter 15 includes a switching element as described above, the capacitor capacity of the capacitive element 31 and the inductance capacity of the inductor element 21 are determined based on the control period of the switching element. That is, the period of the harmonic noise component output from the AC / DC adapter 10 is determined according to the control period of the switch element included in the DC-DC converter 15. Therefore, by determining the capacitor capacity of the capacitive element 31 and the inductance capacity of the inductor element 21 based on the control cycle of the switch element, the harmonic noise component output from the AC / DC adapter 10 can be effectively reduced. Will be able to. Note that only one of the capacitor capacity and the inductance capacity may be set based on the control cycle of the switch element.

  More specifically, it is preferable that each capacitance is determined in proportion to the control cycle of the switch element included in the DC-DC converter 15. For example, when the control cycle of the switch element included in the DC-DC converter 15 is 1/1000, it is preferable to set the capacitor capacity of the capacitive element 31 and the inductance capacity of the inductor element 21 to 1/1000. That is, the capacitor capacity of the capacitive element 31 and the inductance capacity of the inductor element 21 are inversely proportional to the operating frequency of the AC / DC adapter 10 (= the reciprocal of the control period of the switch element included in the DC-DC converter 15). As the frequency increases, each capacity can be set to a smaller value. The fact that it can be set to a small value means that each element can be made small, and the passive PFC 20 can be configured compactly.

  The DC-DC converter 30 includes the capacitive element 31 that also serves as the passive PFC 20, and further includes a switch 32, a control unit 33, a rectifying element 34, an inductor element 35, and a capacitive element 36.

  The DC-DC converter 30 converts the voltage of a DC electric signal (DC output) output from the rectifying element 22 included in the passive PFC 20 by switching of the switch 32. The switch 32 is, for example, a transistor or a MOS-FET.

  The control unit 33 controls on / off of the switch 32 that is a transistor or a MOS-FET in response to an instruction from an information processing device (not shown). Note that the voltage of the output signal of the power supply apparatus 1 varies according to the load included in the information processing apparatus. Therefore, the control unit 33 may autonomously control the on / off of the switch 32 by monitoring the voltage of the output signal of the power supply device 1.

  The controller 33 periodically turns on and off the switch 32 to provide a period during which the voltage output is present and a period during which the voltage output is absent, thereby substantially reducing the voltage. In the power supply device 1, the control unit 33 controls the switch 32 in this manner, thereby realizing output voltage control for each information processing device.

  The capacitive element 31 absorbs input feedback noise generated when the switch 32 is switched. Since the capacitive element 31 is for absorbing the input feedback noise of the switch 32 as described above, the capacitive element 31 is provided in the preceding stage of the switch 32.

  The rectifying element 34, the inductor element 35, and the capacitive element 36 are, for example, a diode, an inductor with an iron core, and a capacitor, respectively, and smooth the electric signal output from the switch 32. That is, the electrical signal output from the switch 32 is an intermittent signal generated by turning on / off the switch 32 as described above. The rectifying element 34, the inductor element 35, and the capacitive element 36 smooth the intermittent signal and output it as a DC electric signal having a constant voltage. The DC electrical signal output in this way becomes the DC output of the power supply device 1 and becomes the drive power supply for the information processing apparatus in the subsequent stage not shown.

  In the power supply device 1 described above, the passive PFC 20 is configured using the rectifying element 22 and the capacitive element 31 that are conventionally provided in the power supply device 1. That is, the harmonic noise component contained in the electrical signal output from the AC / DC adapter can be reduced simply by inserting the inductor element 21 into the conventional power supply device 1. In other words, the power supply device 1 can further reduce the harmonic noise generated at the output of the AC / DC adapter 10 and can suppress an increase in the number of components due to the insertion of the passive PFC 20. It has become. Furthermore, it is possible to reduce the size of the capacitive element 31 and the inductor element 21 that constitute the passive PFC 20.

  The present invention is not limited to the above embodiment. For example, a DC-DC converter including a capacitive element for absorbing input feedback noise can be used in place of the DC-DC converter 30.

  Further, an active PFC may be provided by inserting a control circuit or the like into the passive PFC 20. Also in this case, since the rectifying element 22 and the capacitive element 31 can be used together, the number of parts of the active PFC can be reduced.

It is a circuit block diagram of the power supply device which concerns on embodiment of this invention.

Explanation of symbols

  1 power supply, 5 AC main, 6, 11, 13 filter, 10 AC / DC adapter, 12 rectifier, 14 active PFC, 15, 30 DC-DC converter, 20 passive PFC, 21, 35 inductor element, 22, 34 rectification Element, 31, 36 Capacitance element, 32 Switch, 33 Control unit.

Claims (2)

A rectifying element that limits polarity inversion of the DC output from the AC / DC adapter ;
A first switch element, before Symbol comprises, a capacitor element that will be disposed in the branch between the rectifying element and the first switching element, switching the first switching element in a predetermined period A DC-DC converter that converts a DC output voltage output from the rectifying device into a predetermined DC output voltage;
In the power supply including
An inductor element is inserted between the AC / DC adapter and the rectifying element ,
A passive PFC is configured by the inductor element, the rectifying element, and the capacitive element included in the DC-DC converter .
A power supply device characterized by that. The power supply device according to claim 1,
The AC / DC adapter includes a second switch element for converting a voltage,
At least one of the capacitor capacity of the capacitive element and the inductance capacity of the inductor element is determined based on a control cycle of the second switch element,
A power supply device characterized by that.

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