KR20000002020A - Switching mode power feeding device for minimizing power consumption in stand-by mode - Google Patents

Abstract

PURPOSE: A switching mode power feeding device is provided to reduce the power consumption by minimizing the on-time of a switching transistor in a stand-by mode. CONSTITUTION: A switching mode power feeding device comprises: a switching circuit unit(10) for switching the input power fed to a first winding(N1) of a power trance(T) by responding to the switching driving signal of high frequency; an output power circuit unit(12) for converting the high frequency alternating current induced to a second winding(N2) of the power trance(T) into the direct current and for outputting the converted direct current as the stabilized power; and a first auxiliary power circuit unit(14) for converting the high frequency alternating current induced to a first auxiliary winding(N3) of the power trance(T) into the direct current and for outputting the converted direct current as the auxiliary power of a normal mode.

Description

Switching mode power supply to minimize power consumption in standby mode

The present invention relates to a switching mode power supply, and more particularly, to a pulse width modulation type switching mode power supply capable of reducing power consumption by minimizing on-time of a switching transistor in a standby mode.

In general, in home appliances such as television receivers, stabilization of the operating power supply is inevitably required as the circuit configuration becomes integrated circuit and the signal processing technology becomes high precision. Therefore, the power supply of such household appliances adopts a switching mode power supply.

In addition, the automatic power on / off function, the memory function, etc. are adopted to be multifunctional, so the power supply mode is divided into normal mode and standby mode. In normal mode, power consumption is consumed by the user's needs, but in standby mode, minimal standby power is consumed to perform functions.

However, the standby power is small compared to the hourly power during normal operation, for example 70W, for example, 2W or less. However, since the standby time is long, the overall power consumption cannot be ignored in each home. That is, if the normal operation is 2 hours a day 140W, but the standby time is 22 hours 44W. In addition, the sum of the amount of power consumed in waiting time in all households is significant. Therefore, some users unplug the product when not using the product to reduce power consumption. In this case, the information stored in the memory is deleted to perform the function. There is a problem that can not fully utilize the convenience of use because it can not be.

Moreover, in recent years, as power generation dependent on thermal power generation has been dealt with as an environmental problem related to air pollution, countries not only strongly demand ultra-low power consumption of home appliances, but also especially demand for power saving in standby mode. It is a trend. Therefore, makers are constantly studying in various ways to minimize power consumption in standby mode.

In the conventional switching mode power supply, in order to minimize power consumption in the standby mode, a standby power supply and a standby power supply are configured separately, and in standby mode, the switching frequency is reduced and the switching transistor is minimized compared to the normal mode. This minimizes power consumption in standby mode.

To describe in more detail with reference to Figure 1 will be described a conventional pulse width modulation type switching mode power supply as follows.

As shown in FIG. 1, the power supply device includes a switching circuit unit 10, an output power circuit unit 12, a first auxiliary power circuit unit 14, a second auxiliary power circuit unit 16, a load detector 18, and an optical isolator. 20, a switching controller 22, and a current detector 24.

The switching control unit 22 of the power supply device generates a switching frequency signal corresponding to the standby mode in response to the mode control signal CTL provided to the logic unit 22a and provides it to the pulse width modulation controller 22b. . The switching frequency in the standby mode has a lower frequency than the switching frequency in the normal mode. On the other hand, the variation of the output voltage corresponding to the load variation is fed back via the load detection unit 18 and the optical isolator 20 to be provided to the pulse width modulation controller 22b. Therefore, in the pulse width modulation controller 22b, the on-time of the switching transistor is set according to the given switching frequency signal, and the on-time of the switching transistor is reset in response to the output voltage variation being fed back to divide the interval between the set and the reset. The switching drive signal which has on time is generated. Therefore, the pulse width of the on-time of the switching drive signal is controlled according to the output voltage variation according to the load amount.

However, since the pulse width of the switching drive signal is controlled by such a feedback loop configuration, the pulse width of the switching drive signal cannot be controlled in the standby mode without load fluctuations. Therefore, pulse width control to minimize on-time in the standby mode is impossible. Therefore, in order to minimize power consumption by minimizing on-time in the standby mode, it is necessary to determine the on-time forcibly. Such a forced on-time determination method has a problem of causing system instability.

An object of the present invention is to turn on in the standby mode by controlling the on-time reset of the switching drive signal by using a high-frequency signal induced in the standby power circuit circuit for providing standby power in the standby mode to solve the problems of the prior art. Provides a pulse width modulated switching mode power supply that can reliably minimize time.

Another object of the present invention is to provide a pulse width modulation type switching mode power supply device which is very easy to set the on-time reset timing of the switching drive signal.

1 is a view showing a circuit configuration of a conventional pulse width modulation type switching mode power supply.

2 is a circuit diagram illustrating a pulse width modulation type switching mode power supply apparatus according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: switching circuit section 12: output power circuit section

14: first auxiliary power circuit portion 16: second auxiliary power circuit portion

18: load detector 20: optical isolator

22: switching control unit 24: current detection unit

26: power save circuit

In order to realize the above objects, the apparatus of the present invention comprises a switching circuit section for switching input power provided to the primary winding of the power transformer in response to a high frequency switching drive signal, and high frequency AC induced in the secondary winding of the power transformer. Converts DC into DC and outputs the converted DC to the load as a stabilized power source, and converts the high frequency AC induced in the first auxiliary winding of the power transformer into DC and converts the converted DC into the auxiliary power in normal mode. A first auxiliary power circuit unit for outputting a second auxiliary power circuit, a second auxiliary power circuit unit for converting high frequency AC induced in the second auxiliary winding of the power transformer into direct current, and outputting the converted direct current to an auxiliary power source in standby mode; A current detection unit for detecting a current change in the circuit unit and generating a current detection signal; and the first and second auxiliary power circuit units The on-time of the switching driving signal is set in response to a switching frequency signal whose frequency is varied in response to the normal / standby mode with the power supplied to the operating power source, and the switching driving corresponding to the load amount of the output power circuit part and the current detection signal. A switching control unit for generating the switching drive signal whose pulse width is controlled by resetting the on-time of the signal, and delaying the high frequency AC induced in the second auxiliary winding in the standby mode for a predetermined time in order to minimize the on-time of the switching circuit unit. And a power save circuit unit provided to the current detection signal input terminal of the switching control unit.

In setting the reset time of the on-time in the standby mode, the power save circuit unit may facilitate setting of the value by determining a predetermined time delay amount as a time constant value of a delay circuit composed of a resistor and a capacitor.

Therefore, in the present invention, the high frequency current induced in the auxiliary winding of the second auxiliary power circuit of the forward type in the standby mode is delayed for a predetermined time and provided to the current detection signal input terminal of the switching controller, thereby providing on-time reset timing of the switching drive signal. It can be controlled stably. Therefore, by stably controlling the on-time reset time in the standby mode, it is possible to minimize the on-time of the switching drive signal and effectively reduce the power consumption.

Hereinafter, with reference to the accompanying drawings, it will be described in detail the present invention through an embodiment of the present invention.

2 shows a circuit configuration of a pulse width modulation type switching mode power supply apparatus according to the present invention. In Fig. 2, the same parts as those in Fig. 1 described above are denoted by the same reference numerals.

The power supply device of FIG. 2 includes a switching circuit unit 10, an output power circuit unit 12, a first auxiliary power circuit unit 14, a second auxiliary power circuit unit 16, a load detector 18, an optical isolator 20, It includes a switching controller 22, a current detector 24, and a power supply save circuit 26.

In the switching circuit unit 10, an input voltage Vin is applied to one side of the primary winding N1 of the power supply T and a switching transistor Q1 is connected to the other side. The DC flowing in the primary winding is switched in response to the switching driving signal applied to the gate of the switching transistor Q1.

The output power circuit unit 12 is configured in a flyback manner by connecting a half-wave rectifier circuit composed of a diode D1 and a capacitor C1 to the secondary winding N2 of the power transformer T. The voltage across the capacitor C1 is provided to the load as the output voltage Vout.

The first auxiliary power circuit unit 14 is configured in a flyback manner by connecting a half-wave rectifier circuit composed of a diode D2 and a capacitor C2 to the first auxiliary winding N3 of the power transformer T.

The second auxiliary power circuit 16 includes a half-wave rectifier circuit composed of a diode D3 and a capacitor C3 on the second auxiliary winding N4 of the power transformer T, a resistor R1, a zener diode ZD, The switching circuit consisting of the transistor Q2 and the diode D4 is connected to form a forward method.

The first auxiliary power supply circuit unit 14 provides the auxiliary voltage Vcc in the normal operation, and the second auxiliary power supply circuit unit 16 turns on the switching circuit in the standby operation to provide the auxiliary voltage Vcc.

That is, in the normal operation, the first auxiliary winding N3 has a smaller number of turns than the second auxiliary winding N4, but sufficient energy is induced to generate the auxiliary voltage Vcc. In this case, the second auxiliary winding N4 Since the number of turns is larger than that of the first auxiliary winding N3, more energy is induced to generate a larger voltage than the zener voltage of the zener diode ZD, so that the base potential of the transistor Q2 falls to the ground potential, thereby causing the transistor Q2 to fall. Will not turn on. On the other hand, in the standby operation, since the number of turns of the first auxiliary winding N3 is smaller than that of the second auxiliary winding N4, sufficient energy is not induced, and thus sufficient auxiliary voltage is not generated. However, since the number of turns of the second winding N4 is greater than that of the first auxiliary winding N3, sufficient energy is induced to generate a voltage less than or equal to the zener voltage of the zener diode ZD. Thus, the base potential of the transistor Q2 increases. The transistor Q2 is turned on to generate the auxiliary voltage Vcc.

The load detector 18 detects a change in the output voltage Vout according to the load amount and provides the detected load detection signal to the switching controller 22 through the optical isolator 20.

The switching controller 22 includes a logic circuit 22a and a pulse width controller 22b. In response to the mode control signal CTL, the logic circuit 22b increases the frequency of the switching drive signal in the normal mode and decreases the frequency in the standby mode and the switching control signal that is activated in the standby mode. (SBC) occurs respectively. The pulse width controller 22b is composed of a current mode pulse width controlled general-purpose integrated circuit, and internally generates a trigger signal for setting the on-time of the switching drive signal SD in response to the frequency control signal, and loads fed back. The error signal is amplified by comparing the detected signal with the reference signal, and the on-time of the switching driving signal is reset by comparing the amplified error voltage with the current detection signal. The pulse width controller 22b outputs a pulse width controlled switching drive signal SD whose on time is determined in response to the on time set signal and the reset signal. Therefore, the pulse width controller 22b increases the pulse width, i.e., on-time, to compensate for the decrease when the output voltage decreases as the load increases, and increases the on-time to remove the increase when the output voltage increases according to the load decrease. The output voltage Vout is maintained at a constant level regardless of load variation.

The current detector 24 includes a current sensing resistor R2, a resistor R3, and a capacitor C3 connected between the source and the ground of the switching transistor Q1 to detect a current flowing through the switching transistor Q1. That is, the current detector 24 is for detecting that an overcurrent flows through the switching transistor Q1. This current detection signal is provided to the switching control section 22 as described above to reduce the on-time of the switching transistor Q1, thereby protecting the switching transistor Q1 from overcurrent.

The power supply save circuit unit 26 includes a delay unit DY and a transistor Q3, and the high frequency AC induced in the second auxiliary winding N4 receives the delay unit DY of the resistor R4 and the capacitor C4. After a predetermined time delay, the switching control signal SBC is applied to the base and provided to the current detection signal input terminal of the pulse width controller 22b through the transistor Q3 turned on in the standby mode.

Accordingly, energy is transferred to the second auxiliary winding N4 having the same polarity as the primary winding N1 in the standby mode when the switching transistor Q1 is turned on, and the high frequency alternating current corresponding to the transferred energy is delayed. Is delayed for a predetermined time, i.e., the on time of the standby mode, and when the delayed signal is provided to the pulse width controller 22b, the pulse width controller 22b determines the reset time of the on time in response to this signal. Therefore, the on time reset timing of the switching transistor Q1 in the standby mode can be set by the designer by the RC time constant of the delay unit DY.

In addition, since the control of the on-time reset timing is performed through the feedback loop, the control system system is very stable.

As described above, in the present invention, since the on-time reset timing can be controlled through the feedback loop even in the standby mode, the control system is very stable, and the on-time reset timing can be set by the RC time constant, which is very easy. Can be set to

Therefore, in the present invention, since the on time of the switching transistor in the standby mode can be optimally controlled, power consumption can be effectively reduced by minimizing the on time in the standby mode.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Claims (2)

A switching circuit unit 10 for switching input power provided to the primary winding N1 of the power transformer T in response to a high frequency switching driving signal; An output power circuit unit 12 for converting high frequency AC induced in the secondary winding N1 of the power transformer T into direct current and outputting the converted direct current to a load as a stabilized power source; A first auxiliary power circuit unit 14 converting the high frequency AC induced in the first auxiliary winding N3 of the power transformer T into a direct current and outputting the converted direct current as an auxiliary power in a normal mode; A second auxiliary power circuit unit 16 for converting the high frequency AC induced in the second auxiliary winding N4 of the power transformer T into a direct current and outputting the converted direct current as an auxiliary power in a standby mode; A current detector 24 which detects a change in current of the switching circuit unit 10 and generates a current detection signal; The on-time of the switching driving signal is set in response to a switching frequency signal of which the auxiliary power of the first and second auxiliary power circuits 14 and 16 is supplied as an operating power and whose frequency is changed in response to the normal / standby mode. A switching controller 22 for generating a pulse width controlled switching drive signal by resetting on time of the switching driving signal in response to the load of the output power circuit unit 12 and the current detection signal; And In order to minimize the on-time of the switching circuit unit 10, a power supply for providing a current detection signal input terminal of the switching controller 22 by delaying a high frequency AC induced in the second auxiliary winding N4 for a predetermined time in a standby mode. Pulse width modulation type switching mode power supply characterized by comprising a save circuit section (26). The method of claim 1, wherein the power save circuit section 26 A delay unit (DY) for delaying a high frequency AC induced in the second auxiliary winding N4 for a predetermined time; And a transistor (Q3) for connecting the output of said retarder (DY) to the output of said current detector (24) in response to a standby mode.