JPS58212334A - Charging circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a switching type charging circuit.

In switching type charging circuits, the switching frequency or pulse width is controlled in order to keep the average charging current supplied to the personal computer constant, but for the purpose of ultra-fast charging or miniaturization. If the oscillation frequency is set high, when switching to normal charging, the bus pulse width will become extremely small, and the operation of the switching transistors, diodes, and other elements that make up the circuit may not be able to follow the operation, making it difficult to control the charging current. There was a possibility that the company would be unable to do so.

The present invention has been proposed in view of the above points, and it applies AC voltage generated by a commercial power supply or switching to the primary winding of a transformer, rectifies the voltage induced in the secondary winding, and... In a charging circuit of the type that charges a battery, etc., the secondary winding has a center tag, and the rectified ripple current obtained via a rectifying diode is superimposed on both ends of the secondary winding, or only one side is used. By switching between full-wave rectification and half-wave rectification depending on whether the current is taken out, and by using a timer circuit to perform the switching operation, this charging circuit has a simple configuration that makes it possible to halve the charge K'FIL R, eliminating the drawbacks of the conventional charging circuit. The purpose is to provide

Hereinafter, the present invention will be described in detail with reference to the drawings showing examples.

FIG. 1 is an embodiment of the present invention, and is a circuit diagram showing the basic configuration. In the figure, A'4. A'.

t is an input terminal to which an AC power supply is connected, and terminal A'1
．． The primary winding of the transformer T is connected to A'.

The center tap of the secondary winding of the transformer T is connected to the negative pole of the battery B as a common line, and one end of the secondary winding is connected through a diode D, and the other end is connected through a series circuit of a diode D2 and a transistor Q. and is connected to the positive electrode of battery B via choke coil L.

Further, a diode D3 is connected between the cathode of the diode D and the common line connected to the center tap, and a capacitor C is connected to both ends of the battery B. On the other hand, the pace of transistor Q is I for timer
It is connected to the output terminal of CX, and a resistor and a capacitor for time setting are connected around the timer ICX.

During operation, the AC voltage such as the commercial power supply input from terminal A'1 (4'j) is stepped down by transformer T, diode D, , D2, choke coil L1, capacitor C
Full-wave rectification or half-wave rectification is performed in a rectifier circuit consisting of the following components, and the battery 3 is charged. In other words, when transistor Q is on, it is full-wave rectification, and when it is off, it is half-wave rectification.
FIGS. 2(a) and 2(b) show the voltage changes at both ends B, -82 of the diode D5 during full-wave rectification and half-wave rectification, respectively. By the way, when charging the battery, from the viewpoint of shortening the charging time and preventing battery deterioration, it is preferable to use rapid charging immediately after charging starts, and then switch to normal charging. In the charging circuit of the present invention, when a preset time has elapsed, the timer ICX
operates, turns off the transistor Q, and has the function of automatically switching from quick charging to normal charging at a different charging current.

l Figure 3 shows another embodiment of the present invention □, in which the basic configuration shown in Figure 1 is used as a switching regulator.
This is applied to the next-side rectifier circuit. Broadly classified, rectification/smoothing circuit 1゜switching section 2, control circuit 3,
It is composed of a control circuit electric current 4, a power conversion/rectification/smoothing circuit 5, a charging current switching circuit 6, and a load 7. This type of circuit is called a circuit, and the principle of its operation will be briefly described below.

? In Figure PJ3, the AC voltage input from the commercial power supply terminal A11A2 is full-wave rectified by the rectifier DB, h+, smoothed by the capacitor C4, and then connected to the windings wound on the same magnetic core. L3. It is switched by L4 and switching transistor Q8 + tQB2 and converted into high frequency AC power. The signal waveforms of each part are shown in FIG. 4. Energy excited when the transistor QS1 is turned on is released from the winding L5 through the diode D, and when the transistor Ql11 is turned off, the control circuit 3 turns on the transistor QIl□. works,
Energy excited when transistor Qa2 is turned on
is emitted from winding L4 through diode D2.

At this time, in order to make the charging current A immediately after starting, it is preset by selecting peripheral circuits such as capacitors, and when the π time comes, the timer ICX is activated and turns off the transistor Q, converting the full-wave to half-wave rectification. Switch to Therefore, Fig. 4 (
The current flowing through the diode D2 shown in e) (the shaded area) disappears, and the charging current is reduced to a minimum. That is, when the transistor Q is off, it operates as a so-called feedforward switching regulator. Note that the diode D5Vi is generally called a flywheel diode, and is used to prevent the output voltage from approximately doubling if current does not continuously flow through the smoothing choke coil L. Moreover, the relationship between charging current and battery voltage is shown in FIG. 5 (in) and (b).

As described above, in the present invention, the center tap type 2
In a switching type charging circuit equipped with a transformer having a secondary winding, both ends of the secondary winding are connected through diodes and connected to the battery through a smoothing means, and a transistor is connected in series with one of the diodes. was inserted, and this transistor was controlled by the output of the timer circuit to switch between full-wave rectification and half-wave rectification. It is possible to surprisingly reduce charging [i.

(b) Furthermore, more accurate charging current control is possible by simultaneously using pulse width and frequency control.

(c) Since the charging current can be rapidly reduced to A, it can also be expected to be effective in terms of safety measures such as heat generation.

There are advantages such as

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the basic configuration of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of its operation. 4.4
O□O. a.・Chozuke. , □5 is an explanatory diagram of the operation. T...Trans, Dl, D2. D...Diode, Q...Transistor, X...Timer IC%B
···battery. Figure 1 Figure 4 Figure 5 (a)

Claims (1)

[Claims] In a switching type charging circuit equipped with a transformer having a center-tapped secondary winding, both ends of the secondary winding are connected through diodes and connected to the battery through a smoothing means, A charging circuit characterized in that a transistor is inserted in series with one of the transistors, and the transistor is controlled by the output of a timer circuit to switch between full-wave rectification and half-wave rectification.