JPS60197128A - Automatic voltage switching type 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 [Technical Field] The present invention relates to an automatic voltage switching type charging circuit used in small electric appliances such as electric stoves.

[Background technology]

FIG. 7 shows a circuit diagram of a conventional charging circuit described in Publication No. 11e56-39137. In the figure, A' is a charging circuit consisting of an inverter circuit using a general single transistor.

This is a battery for BFi charging. The inverter circuit that constitutes the charging circuit A' has a wave number of 20 KHz to 30 KHz.
High frequency oscillation is performed, and battery B is charged by rectification at the diode 0 terminal. (I2) is a power supply circuit, which is composed of transistors (+4) (1) and impedance element (16)%. (1 is a rectifier circuit, and AC is an alternating current power supply.

Here, the input voltage V'llf l OOV ~240
Even if Vt changes, the output voltage Vs of the power supply circuit H is kept constant by the switching operation of transistors (14) ((6) in the power supply circuit (121).In other words, when the input voltage is 100V, the transistor O is turned on. The rectified voltage is output as it is, and when the input is 240V, the transistor θX is turned off and the voltage is divided by the isipetance element θψ, and the constant voltage VsKld is output to drive the inverter circuit. In the conventional example, the loss (heat generation) generated by the power supply circuit θ2)K was large, making it unsuitable for small electric appliances such as electric shavers.In other words, in the case of high voltage input such as AC 240V, approximately half the voltage (240V)
0-100) causes a voltage drop in the resistance element θφ and generates heat. Further, the power supply circuit 02) has a problem in that it has a large number of parts and is expensive.

[Purpose of the invention]

Fi is provided in view of the above points,
It is an object of the present invention to provide an automatic voltage switching type charging circuit with high charging efficiency by eliminating unnecessary heat generation and stabilizing the switching operation of an inverter circuit.

[Disclosure of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a basic circuit diagram, in which (4) is a rectifying and smoothing circuit with a resistor R1 and a rectifying bridge Re.

It is composed of a smoothing capacitor 01 and the like. An alternating current input from an alternating current power supply AC passes through a protective resistor R1 and is rectified by a rectifying bridge assistant, and an output voltage N from a rectifying bridge k is smoothed by a capacitor C1. (5) is a switching circuit, and transistor Q□, which constitutes an inverter circuit,
It is composed of a pulse transformer PT, etc., and R4 is the primary winding of the LIFi pulse transformer FT, and R4 is a 1-pin resistor and a diode for absorbing Di spikes. (6) is a base drive circuit, R2 is a base starting resistor, R3 is a resistor, R2 is a secondary winding of the pulse transformer PT, C2 is a pace capacitor, and R2 is a diode for reverse bias. (7) is an output circuit, R3 is the tertiary winding (output winding) of the pulse transformer PT, and R3 is an output rectifying diode. B is the battery to be charged. (2) is an automatic voltage switching circuit, which mainly consists of a negative temperature gradient generating circuit (3) which is the gist of the present invention. This negative temperature gradient generating circuit (3) is connected between the connection point between the resistor R3 and the secondary winding L8 and the ground, and is connected between the resistor R3 and the secondary winding L! Let the voltage at the connection point be Vx. In addition, each circuit (2) (5) + 61 (71 constitutes the charging circuit A:) Here, the general operation of the charging circuit A will be explained. First, the AC input from the AC power supply Vs is rectified. It is full-wave rectified by the bridge tν di Re and is connected to the capacitor C1.
The surface is smoothed. The voltage 'vIN smoothed by the capacitor C1 causes the base current IB to flow to the base of the transistor Q1 by the resistor R2.
.

is turned on to excite the primary winding Ll. Then, the voltage slightly induced in the secondary winding R2 causes the transistor Q□ to be positively biased, resulting in a collector current of 1
c flows to some extent, increasing the voltage induced in the secondary winding R2. As a result, this tendency is further promoted, and the transistor Q1 is suddenly turned on and switched.

The transistor Q1 turns on and the collector current Ic increases, and the voltage between the collector of the transistor Qs and 1599 vCIl! When the collector current I becomes lower, the collector current I
The point at which the increase in c becomes unsustainable (Ic)hfe-IB)
, and for a constant base-emitter voltage vBK, the base current IB tends to decrease, this tendency is reinforced, and the transistor Q1 is instantaneously cut off. Then, when transistor Q1 is off, the tertiary winding R
The energy f- excited in the primary winding L1 is released to the battery B through the diode D3, and the battery B is charged.

Next, the negative temperature gradient generating circuit (
3) will be explained. FIG. 2 shows a specific circuit diagram of the automatic voltage switching circuit (2), which is composed of a transistor Q2% Zener diode D4, a resistor R3, and a negative temperature gradient generating circuit (3). First, collector current 1c is caused to flow so that the voltage value of Vx at the midpoint between transistor Q2Fi, secondary winding R2, and resistor R3 is expressed by the following equation.

Vx = Vz + VB]nz + VFi ■However, vz is the Zener voltage of Zener diode D4, VB
The voltage between the base of E2 transistor Q2 and 1599,'
vfi#-1' indicates the voltage of the minus temperature gradient generation circuit (3).

In other words, the Vx value is when the input voltage VxN is 100 to 240v.
Even if the temperature changes to a certain degree, the voltage generated in the secondary winding R2 is determined by the negative temperature gradient generating circuit (3). In other words, the voltage Vx is determined by the voltage ■, and the base current IB and collector current Ic of the transistor Q1 are determined by the voltage ■, and the collector current Ic is kept constant to stabilize the switch operation of the transistor Q1. . As a result, when the transistor Q1 is forward biased, the base voltage VBK□ or the base current IB of the transistor Q1 changes depending on the input voltage VxN or the load fluctuation (i.e., the number of batteries B or the state of charge of the battery B). It will no longer be affected by changes. As a result, the collector current Ic of the transistor Qt also stops changing, and as a result,
The output current, which is a charging current to battery B, is also equal to the input voltage VxN.
Alternatively, fluctuations due to load fluctuations are eliminated.

Next, the fact that the negative temperature gradient generating circuit (3) has a negative temperature gradient will be explained.

Now, when the output current is increased due to some influence, the total loss of charging circuit A will naturally increase. In other words, heat generation increases. At that time, the voltage of the negative temperature gradient generating circuit (3) with a negative temperature gradient is low, and the voltage Vx is accordingly low. Therefore, the base current IB of the transistor Q1 decreases, and the output current decreases. . Conversely, if the output current decreases, the voltage ■ will increase, working in the direction of increasing the output current. 3 and 4 show specific circuit diagrams of the negative temperature gradient generating circuit (3), with FIG. 3 showing the case of a diode D□, and FIG. 4 showing the case of a thermistor TH. Figure 3 shows diodes D each having a temperature coefficient of -2m V/'C.
□ are arranged in series according to the number (voltage) of batteries B, which are loads. Next, a method for calculating the number of diodes D1 will be shown.

VK=l, 4VXn-1-VBE 1 + R3e I
B -Vz -VBE z ■However, 1.4V battery 1
The true voltage, the number of batteries, VBK□ is the base-emitter voltage of transistor Q1, VBF! 2 indicates the voltage between the base and the terminal of the transistor.

The number of diodes D1 can be calculated using the formula.

However, % is the number of diode D1. Similarly, when using the thermistor TH as shown in Figure 4, the thermistor T
It is sufficient to select a resistance of H.

Figure 5 shows the voltage between the collector and the 1st pin when the negative temperature gradient generating circuit (3) is inserted into the base circuit of the transistor Q1 ((a) in the same figure) and when it is not inserted ((b) in the same figure). It shows the waveforms of VCFj and voltage Vx. As shown in the figure, negative temperature gradient generation circuit (3)
When inserted into the base circuit of transistor Q1, the peak of voltage ■ is suppressed to the value shown in equation 0 above, and similarly, the spike that occurs across primary winding L10 when transistor Q1 is off (v If the peak of Therefore, since the spike in the primary winding L1 that occurs when the switching transistor Q1 is off can be reduced, the withstand voltage of the switching circuit (5) components and the transistor Q can be lowered, and costs can be reduced. .

FIG. 6 shows another embodiment, in which the connection point between the Zener diode D4 and the resistor R5 and the transistor Q! In this embodiment, a negative temperature gradient generation circuit (3) is inserted between the base of the
) controls the transistor Q2.

〔Effect of the invention〕

As described in 1, the present invention provides an automatic voltage that outputs a constant voltage in response to different input voltages and supplies a voltage for driving switching elements of the inverter circuit to a charging circuit consisting of an inverter circuit that charges a battery to be charged. Since a switching circuit is provided and a negative temperature gradient generation circuit for generating a negative temperature gradient is attached to the automatic voltage switching circuit, the switching elements of the inverter circuit are regulated by the automatic voltage switching circuit that outputs a constant voltage. For example, if the input voltage is 100
Even if the voltage changes to ~240V, the current flowing through the switching element remains constant.Therefore, compared to the conventional method that consumes a drop voltage, there is less loss, and charging efficiency increases. It can be charged efficiently, and even if the input voltage is 100 to 240V, automatic switching is possible. Furthermore, even if the current flowing through the switching element fluctuates due to some influence due to the negative temperature gradient generating circuit, the negative temperature gradient generating circuit acts in the opposite direction to the increase or decrease in temperature due to the increase or decrease in heat generation due to the fluctuation. This has the effect of stabilizing the current flowing through the switching element.

[Brief explanation of the drawing]

FIG. 1 is a basic circuit diagram of an embodiment of the present invention, FIG. 2 is a specific circuit diagram of the same as the above, FIG. 3 is a specific circuit diagram of the negative temperature gradient generating circuit of the same as the above, and FIG. Specific circuit diagrams, FIGS. 5(a) and 5(b) are operational waveform diagrams of the same as above, FIG. 6 is a circuit diagram of another embodiment of the same, and FIG. 7 is a circuit diagram of a conventional example. fl) is an inverter circuit, (2) is an automatic voltage switching circuit,
(3) is a negative temperature gradient generation circuit, A is a charging circuit, and B
I/I is a battery to be charged, Dl is a diode, and TH is a thermistor. Agent Patent Attorney Ishi 1) Chief 7 Figure 3 (0) Figure 4 Figure 5 (b)

Claims (3)

[Claims] (1) A charging circuit consisting of an inverter circuit that charges the battery to be charged is equipped with an automatic voltage switching circuit that outputs a constant voltage for different input voltages and supplies the driving voltage for the switching elements of the inverter circuit. An automatic voltage switching type charging circuit comprising an automatic voltage switching circuit and a negative temperature gradient generation circuit that generates a negative temperature gradient. (2) The automatic voltage switching type charging circuit according to claim 1, wherein the negative temperature gradient generating circuit is a diode. (3) The negative temperature gradient generating circuit is a thermistor. An automatic voltage switching type charging circuit according to claim 1, characterized in that: