JP2000308345A - Ac input power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a small-sized, inexpensive, and efficient power source by reducing the output ripples of the frequency of an inputted alternating current, improving the speed of response of a primary-side control circuit, and then, reducing the capacitance of an energy storing capacitor. SOLUTION: A power source with a function for improving the power factor of AC input is provided with a DC-DC converter, the output of which becomes the same as that of an energy-storing capacitor CO2. The speed of response of a primary-side control circuit CON1 is improved by inputted a signal, using an input AC voltage signal to the control circuit of the converter and giving the ratio of the output current of the primary-side control circuit CON1 to that of the converter to the control circuit of the converter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC input power supply, and more particularly, to an economical power supply which achieves high input efficiency and reduces input AC frequency ripple in output voltage.

[0002]

2. Description of the Related Art There has been a one-converter system without an input electrolytic capacitor for a conventional high power factor power supply. However, the conventional one-converter method without an input electrolytic capacitor has a problem that the ripple voltage of the input AC frequency in the output voltage becomes large. As a means for solving this problem, a circuit shown in FIG. 3 is known.

In FIG. 3, AC is an AC power supply, REC
Is a rectifier, T is an output transformer, n1, n2, and n3 are primary windings, secondary windings and tertiary windings, and Q1 is a switching element (MOSFE) connected in series with the primary winding n1.
T1), D1 and CO1 are connected to the secondary winding n2, and form a main rectification output part A.
CO2 is connected to both ends of a tertiary winding n3, and a DC
A diode and a storage capacitor forming an input part of the DC converter, L and Q2 are an inductor and a switching element forming a resonance type boost converter together with the capacitor CO2, D3 is a diode for blocking a reverse current, and a slave output part B is formed by the above. . CON2 is a control circuit for the switching element Q2.

In FIG. 3, the control unit CON1 controls the voltage of the capacitor CO2 on the winding side of the secondary output to be constant, and the control unit CON2 controls the output voltage V0 to be constant. However, the one-side control circuit CON on the primary side
No. 1 requires that the input current waveform be a sine wave having the same phase as the input voltage waveform, while ensuring stability.
For this reason, means for delaying the response speed of the control circuit CON1 to, for example, about several tens times the input AC cycle has been adopted.
Therefore, in order to prevent a response delay when the load RL connected to the output terminal changes suddenly, the energy storage capacitor CO
2 had to be made sufficiently large.

[0005]

SUMMARY OF THE INVENTION The present invention aims at reducing the output ripple of the input AC frequency, and at the same time, controlling the control circuit CON1.
Response speed and the capacity C of the energy storage capacitor
O2 is reduced, thereby providing a small and inexpensive high power factor power supply.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, an invention according to claim 1 includes an AC input, a rectifier for rectifying the AC input, and an output transformer having a primary winding and a secondary winding. An AC-DC converter including a series circuit of the primary winding and a switching element connected between the rectified outputs, a rectified output section connected to the secondary winding side, and an output section connected to the rectified output section. An AC input power supply device having a DC-DC converter connected in common, comprising: a primary-side control circuit for controlling the switching element; and a secondary-side control circuit for controlling the DC-DC converter. The secondary-side control circuit and the secondary-side control circuit use the AC-input rectified output voltage waveform and the output voltage as common control elements.
An AC input power supply device characterized in that an output current of a DC converter and an output current of a DC-DC converter are controlled at a preset distribution ratio. It has made it possible to reduce the capacitance of the storage capacitor and to reduce the ripple of the AC input frequency while increasing the speed.

[0007]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a control target of a primary-side power supply is an output voltage, and a control target of a secondary-side DC-DC converter is for output ripple current compensation of an input AC frequency. The output distribution of the secondary DC-DC converter is determined using the input voltage waveform.

[0008]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is an operation waveform diagram of each part thereof.
The present invention clearly shows the input voltage detection circuit (a) and the current detection circuit (b). There are two control features. 1
The third point is that the output current distribution of the output current (main output A) and the output current of the D / D converter output (sub output B) is determined in advance using the signal waveform from the input voltage (a). Second, both the AC-DC converter and the DC-DC converter are controlled by the output voltage V0, and the response speed of the voltage-controlling amplifier PWM is increased as in the prior art.

In the following, a power supply in the case where the output voltage V0 is stabilized at a constant level will be considered, and a method of distributing the output current using a distribution function will be described. In FIG. 1, the control circuit CON1
Is controlled so that an input current proportional to the input voltage Vin flows, so that the output current i01 has a waveform twice as high as the input voltage, as shown by a waveform i01 in FIG. On the other hand, if the D / D converter outputs power proportional to i02 in FIG. 3C, the output is stabilized. Total output current I
0 is

[0010]

(Equation 1) And is constant. (See I0 in FIG. 2- (C)) DC
-A function f (t) that gives a ratio to the output current i02 of the DC converter is called a distribution function.

[0011]

(Equation 2) Becomes Assuming that the average value of i01 and i02 is the same in the circuit of FIG.

[0012]

(Equation 3) It is expressed as Here, Vin is an AC input voltage iin of the AC-DC converter, and an AC input current. η1 is AC
Assuming that the efficiency of the DC converter, η2, is a good power factor improvement circuit which is the efficiency of the secondary DC-DC converter,

[0013]

(Equation 4) Assuming

[0014]

(Equation 5)

[0015]

(Equation 6) Assume that Here, η1rms and η2rms are the effective values of η1 and η2 in one cycle of the commercial frequency. Then Equation 3 becomes

[0016]

(Equation 7) When η1N × η2M = 1 can be considered,

[0017]

(Equation 8)

## EQU1 ## This example is shown in the circuit of FIG. 1 and the quantity of i02 in FIG. In FIG. 1, a primary side control circuit CON1 is a control circuit of a normal power factor correction type power supply. However, the response speed of the error amplifier for the output voltage V0 is the same as that of the D / D converter, for example, fT = 1KHZ to
It is 10KHZ faster.

Therefore, when a sudden change in the output current occurs,
The response time of CON1 of the conventional control unit is, for example, 0.2 to
While the response time of the control circuit CON1 of the present invention is as fast as, for example, 0.1 m to 1 ms, which is 0.5 second, the capacity of the energy storage capacitor CO2 can be much smaller in FIG. For example, a capacity of 1/10 is sufficient. The cost can be reduced accordingly.

[0020]

As is apparent from the above description, according to the present invention, it is possible to provide a good control circuit for a small, highly efficient, and high power factor AC input power supply.

[Brief description of the drawings]

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

FIG. 2 is an operation waveform diagram of each part of the present invention.

FIG. 3 is a conventional circuit diagram.

[Explanation of symbols]

 AC AC power supply REC Rectifier T Output transformer Q1, Q2 Switching element CON1, CON2 Control circuit RL Load

Claims (3)

[Claims] 1. An AC input, a rectifier for rectifying the AC input, an output transformer including a primary winding and a secondary winding,
An AC-DC converter including the primary winding connected between the rectified outputs, a series circuit of switching elements, and a rectified output connected to the secondary winding; and an output connected to the rectified output. An AC input power supply device having a DC-DC converter connected in common, comprising: a primary-side control circuit for controlling the switching element; and a secondary-side control circuit for controlling the DC-DC converter. The secondary-side control circuit and the secondary-side control circuit use the AC-D as a common control element using the rectified output voltage waveform of the AC input and the output voltage.
An AC input power supply, wherein an output current of a C converter and an output current of a DC-DC converter are controlled at a preset distribution ratio. 2. The AC input power supply according to claim 1, wherein a tertiary winding is provided in the output transformer, and the tertiary winding voltage is used as an input voltage of the DC-DC converter. 3. The AC input power supply according to claim 1, wherein a battery voltage is used as an input section of the DC-DC converter.