JPH0223069Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a power supply compensation circuit that compensates for voltage or current shortages.

[Conventional technology]

In various electrical equipment, there are loads with relatively little current fluctuations and loads with many current fluctuations, and this is especially true for loads such as electric motors, which flow a large current at the time of starting and frequently start and stop. In many cases, measures such as separating the power supply are taken to prevent noise from affecting other loads. For example, in audio equipment, the electric motor and the analog signal system are powered by separate power supplies, and their voltages are also different. In addition, as the overall size of the device has become smaller, the shape of the power supply itself has also become smaller, allowing it to supply sufficient power to loads with large fluctuations in power consumption, such as motors, even at their maximum power consumption. It is becoming a challenge to design a power supply with sufficient margin, and even if it is possible to design a power supply with sufficient margin, the maximum consumption that occurs only in a few cases such as during startup is becoming a problem. It is uneconomical to design a large capacity power supply only for power use.

[Problem to be solved]

In order to eliminate the drawbacks of the above-mentioned conventional technology, the present invention is designed to compensate for the shortfall from other power sources only when there is a temporary shortage of power required for a load with large fluctuations such as an electric motor. An object of the present invention is to provide a power supply compensation circuit that maintains stable operation of the electric motor and the like while minimizing the influence on the load.

[Means for solving problems]

In the power supply compensation circuit according to the present invention, the power supply with the lowest voltage among the plurality of power supplies that supply different voltages to different loads changes the current through a three-terminal regulator that can operate with the input of the entire voltage range of the plurality of power supplies. is connected to a large load, and the other power supplies are directly connected to each independent load, and the above three-terminal regulator is connected via a switch circuit that closes when the lowest voltage power supply drops below a predetermined voltage value. is configured by being connected to the input of

[Effect]

With the above configuration, the switch circuit is normally open, and the lowest voltage power supply supplies the required rated voltage to the motor etc. via the 3-terminal regulator, and the other power supplies supply the required voltage to each load. do. The load current of an electric motor, etc. increases temporarily and 3
When the input voltage of the terminal regulator decreases, a switch circuit between the selected power source and the three-terminal regulator is closed, which connects the selected power source to the three-terminal regulator. No matter which power source is selected, the voltage is higher than the lowest voltage power source, so the load current of the motor is supplied by the selected power source and the lowest voltage, so that the load of the motor, etc. The power shortage will be compensated for.

〔Example〕

The present invention will be described in detail below with reference to the drawings.

Figure 1 shows a preferred example of the power supply compensation circuit according to the present invention.
It is a circuit diagram of an example. In the figure, T1 and T2 are output terminals of two different DC power supplies, and the voltage V1 at the terminal T1 is greater than the voltage V2 at the terminal T2, for example, V1 is 18 volts and V2 is 15 volts. Power supply output terminals T1 and T2 are connected to respective inputs IN of three-terminal regulators 1 and 2, respectively. Further, each output OUT of the three-terminal regulators 1 and 2 is connected to an analog load 4 of an audio signal system and a motor load 3, respectively. A three-terminal regulator is a general term for a power supply voltage or current stabilizing circuit that has three terminals: input terminal IN, output terminal OUT, and ground terminal GND.The most basic configuration is a resistor connected between terminals IN and OUT. A Zener diode is connected between the output terminal OUT and GND, and if necessary, a complex configuration with one or more transistors may be used. Its function is to provide a constant voltage circuit that stabilizes the voltage at the output terminal OUT against current fluctuations in the load connected to the output terminal OUT. Various IC circuits are commercially available, and an appropriate one can be used. can do.
The three-terminal regulator 2 connected to the electric motor 3 is designed to be operable at least for input voltages ranging from the upper limit of power supply voltage V1 to the lower limit of V2.

3 terminal regulator 1 connected to other load 4
The input voltage fluctuation range may be limited to voltage V1 only, or depending on the load 4, the power supply terminal T1 may be directly connected to the load 4 without going through the three-terminal regulator 1.

Next, the power output terminal T1 is connected to the collector of an NPN type transistor Tr, and the emitter of this transistor Tr is connected to the power output terminal T2. Further, the base of the transistor Tr is connected to the output of the comparison circuit 5.

One input of the comparator circuit 5 is connected to a connection point between a resistor R and a Zener diode ZD connected in series between the power supply output terminal T1 and ground, and the other input is connected to the power supply output terminal T2.

Transistor Tr, comparison circuit 5, resistor R, and Zener diode ZD are connected to power output terminals T1 and T.
A switch circuit is formed to connect or disconnect between the two, and the operation of this switch circuit is based on the Zener diode.
Power output terminal T for Zener voltage VZD of ZD
A comparator circuit 5 compares the magnitudes of the two voltages V ₂ and controls the transistor Tr to be turned on or off. That is,
Voltage V ₁ of power output terminal T1 and power output terminal T2
Under the condition that the voltage V ₂ of V ₁ > V ₂ , if VZD < V ₂ , the transistor Tr is turned off;
>V ₂ , the transistor Tr is turned on.

During normal rotation of the motor 3, the load current fluctuates little and the voltage V2 of the three-terminal regulator 2 does not become lower than VZD, so the transistor Tr is off, and therefore the power supply terminals T1 and T2 are independent.

Now, when a large current flows when starting the motor 3, the voltage V2 decreases, and when it becomes smaller than VZD, the transistor Tr is turned on, and as a result, a current flows from the terminal T1 to the motor 3 through the transistor Tr and the three-terminal regulator 2.

That is, the current required to start the electric motor 3 is supplied from both terminals T1 and T2, and the current shortage at the terminal T1 is compensated for by the terminal T2, so that the electric motor 3 can be started with sufficient margin. When the motor 3 shifts to steady rotation and the load current decreases, the voltage V2 at the terminal T2 returns to a predetermined value and becomes larger than VZD, so the transistor Tr is turned off and the terminal T1 is disconnected from the three-terminal regulator 2.

It goes without saying that the switching circuit between the terminals T1 and T2 may be of various types in addition to the above-mentioned embodiments, such as a combination of a voltage S2 detector and a relay circuit.

Alternatively, a plurality of power supplies with different voltages can be connected to the three-terminal regulator 2 through switching circuits, and one of these switching circuits can be selected to close the circuit. .

〔effect〕

According to the present invention, in an electronic device configured to drive a load with large current fluctuations such as an electric motor with an independent power supply, by temporarily supplying the power required for that load from the power supply of another load, It is economical because the power supply circuit can be downsized while minimizing the impact on the load.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of one embodiment of the present invention. 2...3-terminal regulator, 3...Load with large current fluctuation, 4...Load with small current fluctuation, Tr,
R, ZD...Switching circuit.

Claims (1)

[Scope of utility model registration request] A DC power supply with the lowest voltage among the plurality of DC power supplies that supply different voltages to different loads is connected to a load with large current fluctuations through a three-terminal regulator that can operate in the entire voltage range of the plurality of DC power supplies, At least one DC power source among the other DC power sources is connected to the input of the three-terminal regulator via a switch circuit that closes when the lowest voltage DC power source drops below a predetermined voltage value. Features a power supply compensation circuit.