JPH0343820Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention applies to a load such as a control circuit that requires a constant voltage from a battery charging device installed in an engine generator device that operates as an emergency power source. The present invention relates to a DC power supply device in which a transistor circuit is provided in a power supply circuit in parallel with a dropper in order to supply voltage.

[Conventional technology]

FIG. 1 shows an example of a conventionally used device of this kind. In the figure, U and V are the power input terminals of the DC power supply, and CH is the charging device, which is a rectifier consisting of a transformer and diode bridge that receives commercial power and converts AC into DC, and a rectifier that switches the output circuit of this rectifier. Switch SW and Batsuteri
Voltage regulator that supplies switchable voltage to BS
It consists of an AVR and a detection device CB. detection device
CB consists of a detection circuit that detects the battery voltage, a timer that operates the changeover switch SW, and a relay that has a contact S that opens and closes both ends of the dropper D, which is constructed by connecting several diodes in series, according to the battery voltage. configured. LG is a load that does not necessarily require constant voltage, such as an engine starter or generator excitation device that is powered by battery BS, and P is an output terminal connected to the negative terminal of contact S and dropper D, which is connected to negative output terminal C. A control circuit for controlling the operation of the load device LG along with the terminal N
Connected to SC. This control circuit includes an electronic circuit, a relay, etc. for controlling the operation of the load device LG, so this is a load that requires constant voltage power supply. A power supply circuit is constituted by the dropper D and the relay contact S, through which power is supplied from the battery to the control circuit SC which requires constant voltage.

When charging a battery, there are two types: equal charging, which charges at a relatively high voltage, and floating charging, which charges at a low voltage that maintains the battery voltage. When the commercial power supply is cut off, it is connected to a constant voltage device AVR that outputs an equal charging voltage by setting a timer.
When commercial power is turned on, this equal charging voltage is applied to the battery BS.

At the beginning of charging, the battery BS is charged with a constant current, and this voltage gradually rises, and when it reaches a predetermined equal charging voltage, it is thereafter charged at a constant voltage with this equal charging voltage, and the charging voltage of the battery BS changes accordingly. and rise. When the charging voltage of the battery BS reaches a certain set value, the detection device CB operates and the contact S is opened, so that the battery voltage BS passes through the dropper D and is lowered by the forward resistance and output. To illustrate this, the changes in the battery voltage and the power supply circuit output voltage with charging time are as shown in FIG. 2, and as shown in FIG. 2, they gradually decrease. At this time, the timer in the detection device CB is restarted, and equal charging continues for a certain period of time, so that the battery BS voltage almost approaches the equal charging voltage. Changeover switch SW when timer operation ends
is switched, moving from equal charging to floating charging.

During floating charging, a voltage lower than equal charging will cause battery damage.
Added to BS. The battery BS is in a fully charged state before the timer ends, and when equal charging is stopped, the voltage drops to a voltage lower than the equal charging voltage, that is, the voltage at full charge. For floating charging, it is sufficient to apply a voltage sufficient to maintain the full charge voltage, so a constant voltage lower than the equal voltage is applied at this time, and the battery BS voltage is maintained constant.

At this time, the detection device CB operates, the contact S is closed, and the battery voltage BS is output with almost no drop.

As mentioned above, the control circuit SC is supplied with a voltage with a large fluctuation range, which may cause relays, electronic circuits, etc. built into this circuit to malfunction, causing damage to the load equipment.
There was a risk that the LG would malfunction.

[The problem that the idea aims to solve]

The purpose of this invention is to eliminate the above-mentioned drawbacks and to provide a device that outputs a constant voltage.

[Means to solve the problem]

In order to achieve this purpose, according to this invention, a dropper D is inserted between the battery BS and the output terminal in the power supply circuit, a transistor is provided in parallel with the dropper D, and this transistor is controlled to output a constant voltage. This is a DC power supply device.

〔Example〕

The structure and operation of an embodiment of this invention will be explained below with reference to FIGS. 3, 4, 5, 6, and 7. In the figure, U, V, B, C,
BS, P, N, LG and SC are the same as those explained in FIG. 1, so their explanation will be omitted.

CH is a charging device that includes a rectifier consisting of a transformer and diode bridge that converts alternating current to direct current, a switch SW that changes the output circuit of this rectifier, a voltage regulator AVR that supplies switchable voltage to the battery BS, and It consists of a detection device CB and a detection device CB. The detection device CB consists of a detection circuit that detects the battery voltage, and a timer that continues the equal voltage for a certain period of time from when the battery BS reaches the set voltage by this detection, and operates the changeover switch SW when the detection ends.

Insert the dropper D between the battery battery BS and the output terminal P with the positive terminal on the battery side, connect the emitter of the transistor _T1 to the positive terminal of the dropper D, connect the collector of this transistor _T1 to the negative pole, and connect the dropper D and the transistor. Connect T ₁ in parallel. A resistor R ₁ ,
_R2 are connected in series, the connection point thereof is connected to the base of the transistor _T1 and the emitter of the transistor _T2 , and the collector of the transistor _T2 is connected to the positive terminal of the dropper D. A constant voltage diode ZD and a resistor _R3 are connected in series between battery output terminals B and C, and this connection point is connected to the base of a transistor _T2 .

It is configured as described above. In this configuration, the switching switch of the charging device CH is a constant voltage device that outputs an equal charging voltage when the commercial power supply is cut off.
When connected to the AVR and commercial power is turned on, equal voltage is applied to the battery BS.

At the beginning of charging, the battery BS is charged with a constant current, and the battery BS voltage gradually increases. However, at this time, the voltage is low, so the current flows through the constant voltage diode.
Transistor T ₂ remains non-conducting since no voltage flows through ZD and therefore no voltage develops across resistor R ₃ .
On the other hand, the voltage across the divided resistor _R1 is applied between the emitter and base of the transistor _T1 , making it fully conductive, so that the battery BS output drops to the dropper D.
Instead, it passes through this transistor _T1 and is output between the output terminals P and N. Changes in battery BS voltage and power supply circuit output voltage due to charging time are the fourth
As shown in the figure, at the initial stage of charging, the voltage of the battery BS is output with almost no drop, as described above and shown in this figure.

The current flow rate of transistor T ₂ is as shown in Figure 5, and there is almost no current flow at the beginning of charging, and the current flow rate of transistor T ₁ is as shown in Figure 6, and it is 100% at the beginning of charging. It is almost completely energized.

Evenly charging continues and the battery becomes BS from the beginning of charging.
When the voltage rises, current flows through the constant voltage diode ZD to the resistor _R3 , and voltage is applied between the base and emitter of the transistor _T2 , and the collector and
Since the emitter becomes conductive and the emitter current is limited by the voltage across resistor _R3 , the voltage across resistor _R1 connected in parallel with transistor _T2 is lower than when transistor _T2 is not present. It will be done. That is, if the transistor _T2 were not present, the current flowing through the resistor _R1 would increase as the voltage of the battery BS increases, and the voltage across the resistor _R1 would also increase. but,
Thanks to the existence of this transistor T ₂ , as the voltage of the battery BS increases, a large base current is supplied to the transistor T ₂ via the voltage regulator diode, increasing its conductivity, and should flow to the resistor R ₁ . Underwrites the increase in current. Therefore,
Even if the voltage of the battery BS increases, the current flowing through the resistor _R1 hardly changes, and the voltage across the resistor _R1 also hardly changes. Since the voltage across the resistor _R1 , which is kept almost constant in this way, is applied between the base and emitter of the transistor _T1 , the terminal P, which is applied to the control circuit SC, due to the action of the transistor _T1 , The voltage across N is kept constant regardless of the voltage rise of battery BS.

In this constant voltage operation, the voltage drop across transistor _T1 increases as the battery voltage increases. The characteristics of the current in the dropper D and its voltage drop are as shown in Fig. 7, so while the voltage drop across the transistor _T1 is small, the current flowing through the dropper D is small, and most of the load current flows through the transistor _T1.
flows through. As the battery voltage rises, the voltage drop of transistor _T1 increases,
When this exceeds a predetermined value, the current flowing through the dropper D increases rapidly, and eventually most of the load current comes to flow through the dropper D. At this time, as described above, the timer in the detection device CB starts a timed operation, and uniform charging is maintained for a certain period of time. Since this timer performs a reset operation at the end of the timed operation, the changeover switch SW is changed to shift from equal charging to floating charging.

Since it is sufficient to apply a voltage sufficient to maintain floating charge, a voltage lower than that for uniform charging is applied from the charging device CH. At this time, terminal B of battery BS,
Since the voltage across C decreases, the transistor _T1 shifts to constant voltage operation again.

As mentioned above, when the battery terminal voltage is below the operating voltage of the constant voltage diode ZD, the transistor _T1 becomes completely conductive and guides the battery terminal voltage to the control circuit SC without voltage drop, so that the battery terminal voltage becomes a constant voltage. When the operating voltage of the diode ZD is exceeded, it performs constant voltage operation and supplies a constant voltage to the control circuit SC. For the high battery terminal voltage that occurs only at the end of equalizing charging, by having the dropper take charge of most of the load current, accurate constant voltage characteristics will be lost, but this degree will depend on the control circuit SC. This is acceptable, but rather the advantageous effect is that the load on the transistor _T1 can be reduced and its size can be reduced. In other words, if the constant voltage characteristic of transistor T ₁ is forced even in such a high battery terminal voltage range, transistor T ₁ has to bear the entire load current while producing a _large voltage drop. Power loss is large and heat generation increases. Therefore, even if such a high battery terminal voltage occurs only for a very short time out of the total operating time, the transistor _T1 should be a large one with a large cooling body. You will be forced to use the .

〔Effect of the invention〕

As mentioned above, according to this invention, the charging device
Transistor in parallel with dropper D on the output side of CH
To connect T ₁ and control this transistor T ₁ , voltage dividing resistors R ₁ , R ₂ , constant voltage diode, resistor
A transistor T ₂ connected in parallel with R ₃ and voltage dividing resistor R ₁ is provided so that a constant voltage is always output even if this voltage changes when the battery BS is charged equally or floatingly. In the conventional device, as the battery voltage changes when the equal and floating charge states change, a voltage with a range of up and down steps is supplied to the control circuit SC, so that the relays, capacitors, and semiconductors in the control circuit SC are However, according to the present invention, with the simple configuration described above, a nearly constant voltage can be supplied to the control circuit SC even if the charging state changes. Therefore, the present invention can eliminate the above-mentioned drawbacks and is extremely effective in practice.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing a conventional DC power supply, Figure 2 is a battery output and power supply circuit voltage vs. charging time characteristic diagram of the conventional power supply, and Figure 3 is an example of the DC power supply of this invention. Figure 4 is a battery voltage and power supply circuit voltage vs. charging time characteristic diagram, Figures 5 and 6 are transistors T ₂ and T ₁ current flow ratio vs. charging time characteristic diagram, and Figure 7 is a circuit diagram showing the characteristics. is a drop voltage vs. load current characteristic diagram of Dropper D. U, V...Power input terminal, CH...Charging device,
B, C...Positive pole, negative pole output terminal, D...Dropper, _T1 ...Transistor, _T2 ...Transistor,
P, N...Power supply circuit output terminal, SC...Load that requires constant voltage power supply (control circuit), LG...Load device such as a generator, BS...Battery, ZD...Constant voltage diode, _R1 , R ₂ , R ₃ ... Resistor, SW ... Changeover switch, AVR ... Constant voltage device, CB ... Detection device.

Claims (1)

[Claim for Utility Model Registration] Connection between a charging device CH that outputs a DC charging voltage that can be switched between a high-value equal charging voltage and a low-value floating charging voltage, and the output terminal of this charging device. battery BS and a load SC that requires constant voltage power supply.
A series diode dropper D is inserted in the power supply path between the battery terminals and lowers the high battery terminal voltage generated at the end of equal charging and guides it to the load; and a transistor _T1 connected in parallel to the series diode dropper. , depending on the terminal voltage of the battery, when the voltage is a low value, the transistor is sufficiently conducted so as to lead the voltage to the load without dropping;
Control means T ₂ , ZD, R ₁ for adjusting the degree of conductivity of the transistor to be low in order to lower the voltage in accordance with the value when the voltage is a high value and guide it to the load;
A DC power supply device comprising ~R ₃ and.