JPH1155862A - Power circuit - Google Patents

Abstract

(57) [Problem] To provide a power supply circuit for efficiently operating a plurality of load circuits having different operating voltages by a plurality of battery power supplies having the same capacity. A first and second battery power source (B) having the same capacity is provided.
T1, BT2 and BT3, BT4) and a first load circuit RL by a third battery power supply (BT1 to BT4).
1 and a comparator iC1 for comparing the terminal voltages of the first and second battery power supplies.
A switching circuit comprising relays RY1 to RY4 for selecting the first or second battery power source having a higher voltage based on the output of C1 is provided, and the first or second battery power source selected by this switching circuit is switched to the second battery power source. To the load circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a power supply circuit using a battery power supply, and more particularly to a power supply circuit having a plurality of load circuits requiring different power supply voltages.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram of the prior art. In FIG. 2, RL1 and RL2 are load circuits having different operating voltages, and BT1, BT2, BT3 and BT4 are batteries connected in series, and the batteries BT1 to BT4 are connected in series to a load circuit RL1 having a high operating voltage. Supply the connected voltage.

[0003] Reference numeral 1 denotes a constant voltage circuit which uses a terminal voltage of a power supply in which the batteries BT1 to BT4 are connected in series as an input voltage and outputs a DC voltage required for a load circuit RL2 having a low operating voltage. The output terminal is connected to the load circuit RL2. Thus, the load circuit R requiring a high voltage
The supply voltage to L1 is reduced by the constant voltage circuit 1, and the supply voltage to the load circuit RL2 that operates at a low voltage is output.

[0004]

When a load having a different operating voltage is driven by a battery power supply, in the above-described prior art, a high voltage is stepped down by a constant voltage circuit to produce a low voltage, and both loads are used to load both loads. Each is driven.
Therefore, a loss due to the voltage drop in the constant voltage circuit occurs. This loss is the product of the current flowing through the load that operates at a low voltage and the voltage drop by the constant voltage circuit, resulting in poor power supply efficiency and short battery life.

[0005]

According to the present invention, there is provided a power supply circuit comprising a first battery power supply and a second battery power supply having the same capacity and connected in series. In a power supply circuit provided with a battery power supply, a first load circuit connected to the third battery power supply, and a second load circuit operating on the first or second battery power supply, the second load circuit , A switching circuit for selectively switching a battery power supply for the second load circuit to one of the first battery power supply and the second battery power supply.

According to a second aspect of the present invention, in the power supply circuit of the first aspect, a comparison circuit for comparing the terminal voltages of the first and second battery power supplies is provided, and the switching circuit is provided with the comparison circuit. When the output of is inverted, the second load circuit is temporarily disconnected from the battery power supply, and while the second load circuit is disconnected from the battery power supply, the second load circuit is disconnected based on the output of the comparison circuit. The battery power supply having the higher terminal voltage among the first and second battery power supplies is connected to the second load.

According to a third aspect of the present invention, there is provided the power supply circuit according to the second aspect, wherein the comparison circuit has a hysteresis characteristic.

The power supply circuit according to claim 4 is a power supply circuit according to claim 2,
3. The power supply circuit according to claim 3, further comprising: an offset circuit for deviating a reference voltage of the comparison circuit from an initial value of the first or second battery power supply, wherein one of the first and second batteries is operated at an initial operation. A battery power source is selected.

According to a fifth aspect of the present invention, in the power supply circuit according to any one of the first to fourth aspects, a voltage supply source is provided in parallel with the second load circuit.

According to the above configuration, the third battery power source in which the first battery power source and the second battery power source having the same capacity are connected in series is always connected to the first load circuit having a high operating voltage. Alternatively, since the second battery power source is selectively connected to the second load circuit having a low operating voltage by the switching circuit, the first or second battery power source is switched and used according to the degree of consumption. And the use efficiency of the battery power supply can be improved.

Further, according to the power supply circuit of the second aspect,
The terminal voltages of the first and second battery power supplies are compared by a comparison circuit, and the output of the comparison circuit connects the first or second battery power supply having the higher terminal voltage to the second load circuit by a switching circuit. Therefore, the first and second battery power sources can be automatically averaged and used, preventing uneven consumption of the first or second battery power source and efficiently using the battery power source. it can.

Further, when the switching circuit switches the battery power supply connected to the second load circuit to the first or second battery power supply having a higher terminal voltage, the second load circuit is temporarily connected to the battery. After the power supply is disconnected from the power supply and the first or second battery power supply is connected, the second load circuit is energized.
A high voltage is not supplied from the battery power supply of the third embodiment, and the second load circuit can be protected from destruction due to application of a high voltage from the third battery power supply.

According to the power supply circuit of the third aspect,
Since the comparison circuit has a hysteresis characteristic, chattering does not occur when the power supplied to the second load circuit is switched from the first to the second or the second to the first battery power. And the switching of the second battery power supply can be performed smoothly.

According to the power supply circuit of the fourth aspect,
Since an offset circuit is provided to deviate the reference voltage of the comparison circuit from the initial values of the first and second battery power supplies, the first terminal voltages of the first and second battery power supplies are exactly the same. However, one of the preset battery power sources can be connected to the second load circuit with priority, and the selection of the first or second battery power source by the comparison circuit and the switching circuit at the initial stage can be performed. It can be performed smoothly.

According to the power supply circuit of the fifth aspect, since the voltage supply source is provided in parallel with the second load circuit,
Even when the supply of voltage from the battery power supply to the second load circuit is interrupted when the first or second battery power supply connected to the second load circuit is switched, the second load circuit is temporarily connected to the second load circuit. Since the required voltage is supplied from the voltage supply source, malfunction of the second load circuit can be prevented.

[0016]

FIG. 1 is a circuit diagram of an embodiment of the present invention. In FIG. 1, BT1, BT2, BT3, BT
4 is a battery, respectively DC output voltage are equal, these batteries BT1, BT2, BT3, BT4 are connected in series, and outputs the terminal voltage V _0. RL1 is the battery BT
1, BT2, BT3, connected to the serially connected battery power BT4, a load circuit operating at the terminal voltage V _0, RL2 at voltages V ₁ or V ₂ of the 1/2 of the terminal voltage V ₀ It is a load circuit that operates.

RY1, RY2, RY3, and RY4 are relays, each of which has an a terminal, a b terminal,
A COM (common) terminal is provided, and when the coil of each relay is energized, the COM terminal is connected to the b terminal, and when no current is applied, the COM terminal is connected to the a terminal.

The load circuit RL2 is connected between the COM terminals of the relays RY1 and RY4.
COM terminal of relay 2 and relay RY3
1 and each a terminal of the relay RY4. Also,
And a terminal of the relay RY2, is between the terminal b of the relay RY3, the battery BT1, BT2, BT3, battery power source series connected terminal voltage V ₀ which BT4 are connected, b terminals of the relay RY2 and the relay RY3 Is connected to a connection point T between the batteries BT2 and BT3.

RA, RB are resistors having the same resistance value, and are connected in series to form the batteries BT1, BT2, BT3, B
The potential at the connection point between the two resistors RA and RB is divided by the resistor RC and RD and supplied to the (-) terminal on the input side of the comparator iC1. The potential at the connection point T between the batteries BT2 and BT3 is supplied to the (+) terminal on the input side of the comparator iC1.

TS is a timer switch that keeps the output at "H" for a fixed time when the output of the comparator iC1 is inverted. The output of the timer switch TS drives the coils of the relays RY1 and RY4. D is a delay switch for delaying the output of the comparator iC1 and outputting the delayed signal.
2 and RY3 coils are driven.

Reference numeral iC2 denotes a hysteresis circuit for stabilizing the operation of the comparator iC1. A reference signal RET of 1 / 2V ₀ is supplied to a (+) terminal on the input side, and a (-) terminal on the input side. Is connected to the output terminal of the comparator iC1, and the output terminal is connected to the (−) terminal on the input side of the comparator iC1 via a resistor RF. C1 is a charging capacitor provided in the power supply of the load circuit RL2.

Since the embodiment of the present invention has the above configuration, the batteries BT1 and BT2 and the batteries BT3 and BT4 will now be described.
Assuming that the terminal voltages connected in series are equal, V ₁ =
Since V ₂ = ＶV ₀ and the resistances RA and RB are equal, the voltages V ₃ and V ₄ between the terminals of the resistances RA and RB are V ₃ = V ₄ = V ₁
= V ₂ = １ ／ V ₀ . Furthermore, (+) input of comparator iC1 is V ₂ = V _0/2, and the (-) input V ₅ is V ₄
× RD / (RC + RD) = RD · V 0/2 (RC + R
D), and therefore, the output of the V _2> V ₅ next comparator iC1 becomes "H".

The output of the timer switch TS becomes "H" for a certain fixed time when the input changes. The delay switch D outputs "H" with a certain delay after the input becomes "H". Similarly, when the input is "L", the output also changes to "L" with a certain delay. Become. Therefore, as described above, when the output of the comparator iC1 becomes “H”, the output of the timer switch TS becomes “H” for a certain period. As a result, current flows through the coils of the relays RY1 and RY4, the terminals b and COM of the relays RY1 and RY4 are connected, and power is not supplied to the load circuit RL2.

During this time, the output of the delay switch D becomes "H" with a slight delay. As a result, relays RY2 and RY3
Current is supplied to the coils of the relays RY2 and RY3 and the terminals b and COM of the relays RY2 and RY3 are connected. Then, after a lapse of a certain time, the output of the timer switch TS becomes “L”,
The energization to the coils of the relays RY1 and RY4 is interrupted to connect the a contact and the COM contact of the relays RY1 and RY4,
Battery power in which batteries BT3 and BT4 are connected in series is supplied to the load circuit RL2.

At the initial stage when the voltages of the batteries BT1, BT2, BT3, and BT4 are equal, a stable operation can be performed by the above initial value offset circuit. That is, in the initial state, when the voltages of the batteries BT1 to BT4 are equal, the resistors RC and RD are connected to the (−) terminal on the input side of the comparator iC1 so that the output of the comparator iC1 is stabilized.
And set so that the voltage on the (-) side always decreases.

As described above, the relays RY1 to RY1
Of the changes in the output of the comparator iC1 in Y4,
Be sure that the relays RY1 and RY4 switch first and the load circuit R
L2 is temporarily opened. And the relay RY2
And RY3 are switched with a delay, and then the relay RY1
And RY4 are again connected to the a contact and the COM contact. Above, such as, high voltage V ₀ is prevented from leading directly to the load circuit RL2 by deviation of the timing of switching of the relay.

[0027] When switching the respective relay RY1~RY4 above, high voltage V ₀ is applied to the load circuit RL2 momentarily even lead is b and COM terminals of the relay RY3 connection is a terminal and COM terminal of the relay RY2, There is a risk of breaking the load circuit RL2. In order to avoid this, at the moment when the battery power is switched, the load circuit RL2
Open.

However, the voltage across the load circuit RL2 is ensured by the capacitor C1. When the load current of the load circuit RL2 is large, a secondary battery may be used instead of the capacitor C1. After the switching between the relays RY2 and RY3 is stabilized, power is supplied again via the relays RY1 to RY4. The timing circuit for making the timing for switching the battery power supply by the relays RY1 to RY4 performs the above operation.

When the output of the comparator iC1 becomes "H", the (-) input side of the hysteresis circuit iC2 becomes "H". The (+) input side of the comparator iC1 is connected to R ^Ef , and 、 V ₀ is always applied. As described above, when the (-) input side of the hysteresis circuit iC2 becomes "H", the output of the hysteresis circuit iC2 becomes "L", the resistance RF enters in parallel with the resistance RD, and the (-) input side of the comparator iC1 further increases the voltage. Goes down.

Therefore, once the output of the comparator iC1 becomes "H" once, the potential difference between the (+) input side and the (-) input side further expands, and the operation is stabilized. This is a hysteresis circuit for performing switching smoothly. If this hysteresis circuit is not provided, the output of the comparator iC1 repeats "H" and "L" with a slight potential difference, and the operation becomes unstable. The output of the comparator iC1 is (+)-side voltage − (−)-side voltage × G of the comparator iC1.
_V (G _V is the open-circuit gain of the comparator iC1).
The above is a series of operations at the time of initial power supply.

Next, the initially connected batteries BT3 and BT
The operation when the voltage of the battery power supply consisting of No. 4 drops will be described. When the terminals b and COM of the relays RY2 and RY3 are connected, the battery supplies power to the load circuit RL2 from a battery power source composed of BT3 and BT4. When the above-described state of supplying power to the load circuit RL2 continues, the voltages of the batteries BT3 and BT4 decrease.

The dropped voltage is applied to voltage dividing resistors RC and R
A voltage drop exceeding an initial value offset circuit composed of D and a resistor RF and a voltage drop composed of a hysteresis circuit iC2;
When the relationship between both inputs of the comparator iC1 is inverted, the output of the comparator iC1 becomes “L”. As a result, the input of the timer switch TS changes, and the output thereof becomes "H" for a predetermined constant time, during which the relays RY1 and RY4
Is connected to the b terminal and the COM terminal.

The output of the delay relay D becomes "H" with a delay of a predetermined time after the output of the comparator iC1 is inverted.
From “L” to “L”, and the CO of relays RY2 and RY3
The M terminal is connected to the a terminal. After a certain period of time, the output of the timer switch TS switches from "H" to "L", the COM terminals of the relays RY1 and RY4 are connected to the terminal a again, and power is supplied to the load circuit RL2. In this case, the power supply source is relays RY2 and RY.
The batteries BT1 and BT2 are connected to the terminal a of No. 3.

By the above-described battery switching, the output of the comparator iC1 becomes "L" and the hysteresis circuit i
The output of C2 becomes "H". As a result, the resistance R
Although the parallel circuit of the resistors RD and RF is connected in series with C, the parallel circuit of the resistors RC and RF enters the series with respect to the resistor RD when the output of the hysteresis circuit iC2 becomes “H”. That is, the input voltage on the (−) side of the comparator iC1 rises and has a hysteresis characteristic.
The output of the comparator iC1 is stabilized by this hysteresis circuit.

As described above, since the voltages of a plurality of battery power sources are constantly compared and the battery power source used for a specific load is switched to the optimum one, the use efficiency of the battery power source can be improved. . In the above embodiment, the comparator iC1, the hysteresis circuit iC2,
The timer switch TS and the delay switch D operate as a part of the load circuit RL1.

In the embodiment of the present invention described above, the battery power is switched using a relay. However, the present invention can be similarly implemented using a semiconductor switch such as a transistor, an FET, or an iC.

[0037]

According to the present invention having the above structure, a plurality of batteries of the same capacity connected to a load circuit operating at a high voltage by a switching circuit are connected to a battery power supply connected to one load circuit operating at a low voltage. Since the power source can be selected, the battery power source can be used efficiently and effectively.

Further, since the battery power supply having a high voltage is always detected by the comparison circuit and the detected battery power supply is connected to one load by the switching circuit, the consumption of a plurality of battery power supplies is made equal. The use efficiency of the battery can be further improved. Further, at the time of switching of the battery power supply, the load circuit in which the battery power supply is switched is once disconnected from the battery power supply, so that the application of overvoltage to this load circuit can be prevented, and the load circuit can be prevented from being damaged by the overvoltage application. .

The switching circuit for switching the battery power has a hysteresis characteristic, so that the switching operation can be performed stably. Further, since the comparison circuit has an offset circuit, a specific battery power source can be selected even during the initial operation of the battery power source, and the switching of the battery power source during the initial operation of the battery power source is stabilized. Can be performed reliably.

Further, since the load circuit to which the battery power source is switched is provided with a voltage supply source, even if the load circuit is temporarily disconnected from the battery power source when the battery power source is switched, the voltage supply from the voltage supply source is reduced. Supply is performed, and the operation of this load circuit can be stably continued.

[Brief description of the drawings]

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

FIG. 2 is a circuit diagram of a conventional example.

[Explanation of symbols]

 BT1, BT2, BT3, BT4 Battery RL1, RL2 Load circuit RY1, RY2, RY3, RY4 Relay iC1 Comparator iC2 Hysteresis circuit TS Timer switch O ... delay switch C1 ... capacitors RA, RB, RC, RD, RF ... resistors

Claims (5)

[Claims] A first battery power supply having a first battery power supply and a second battery power supply having the same capacity connected in series; a first load circuit connected to the third battery power supply; Alternatively, in a power supply circuit provided with a second load circuit that operates on a second battery power supply, the battery power supply for the second load circuit is selectively selected from one of the first battery power supply and the second battery power supply. A power supply circuit provided with a switching circuit for switching. 2. A comparison circuit for comparing the terminal voltages of the first and second battery power supplies, wherein the switching circuit temporarily switches the second load circuit when the output of the comparison circuit is inverted. While the second load circuit is disconnected from the battery power source while the second load circuit is disconnected from the battery power source, the battery power source having the higher terminal voltage of the first or second battery power source based on the output of the comparison circuit. 2. The power supply circuit according to claim 1, wherein the power supply circuit is connected to a second load. 3. The power supply circuit according to claim 2, wherein said comparison circuit has a hysteresis characteristic. 4. An offset circuit for deviating a reference voltage of said comparison circuit from an initial value of said first or second battery power supply, and said first or second battery power supply at an initial operation. The power supply circuit according to claim 2, wherein the power supply circuit is selected. 5. The power supply circuit according to claim 1, wherein a voltage supply source is provided in parallel with said second load circuit.