SU1501013A1 - D.c. voltage stabilizer with current overload protection - Google Patents

Abstract

This invention relates to electrical engineering and can be used in secondary power supply sources. The goal is to increase K, P, D and expand functionality. The introduction of a capacitor 7 between the base of the protection transistor 2 and the emitter of the control transistor 1 generates a time-varying output characteristic of the stabilizer when the load current is limited. Due to this, it is possible to establish a small short circuit current and thereby increase K, P, D, but to provide a large initial current when switched on to a discharged capacitance and, consequently, a short transient time. 1 il.

Description

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The invention relates to electrical engineering and can be used to protect nocTOH: iHoro voltage sources from exceeding the permissible load current.

The purpose of the invention is to increase efficiency and enhance functionality.

The drawing is a schematic diagram of a constant voltage regulator with a zap (and it is due to overcurrent.

The stabilizer contains a control transistor 1 connected in series to the power bus, protectors} and w transistor 2, the collector of which through a current limiting resistor 3 is connected to the power input terminal, a resistive divider of resistors 4 and 5, the output of which is connected to the base of the protective transistor, resistive sensor 6, connected in series with the regulating transistor 1, the capacitor 7 connected between the base of the protective transistor 2 and the emitter of the regulating transistor 1, the control unit 8 connected between the common w hydrochloric regulating transistor and the base 1.

The stabilizer works as follows.

When the supply voltage is connected, the load current is maximum and is determined by the equality of the voltage drops on the current sensor 6 and the offset emitter junction of the protective transistor 2. As the capacitor 7 charges, the level of load current limiting decreases as the voltage on the capacitor 7 is summed with the voltage drop across current sensor 6. In steady state, the voltage across capacitor 7 and, therefore, the level of limiting the load current is determined by the ratio of the resistances of resistors 4 and 5 of the divider. Such a change in time

limiting the load current allows the stabilizer to quickly enter the mode, even if the load has a capacitance}

character It is advisable that the time constant of the protection node, defined by the capacitor 7 and the resistor 5, be chosen to be longer than the load time constant.

When a short circuit occurs at the output, the load current at the first moment of time does not change, therefore, if the overload is short-term, the return of the stabilizer to the mode also occurs relatively quickly. With a long short circuit, the load current decreases as the capacitor 7 is charged, which reduces the dissipated power and increases the efficiency of the stabilizer.

Claims (1)

Invention Formula A constant voltage regulator with protection against overcurrent, containing a control transistor connected in series to the power bus according to a common-collector circuit and a resistive current sensor, a protective transistor whose emitter is connected to the power output terminal, and the collector is connected to the base of the control transistor connected through the current limiting resistor to the power input terminal, and the base of the protective transistor is connected to the output of a resistive divider connected between the collector and the emitter control transistor, and a control node connected between the common bus and the base of the control transistor, characterized in that, in order to increase efficiency and enhance functionality, a capacitor is inserted into it, connected between the base of the protective transistor and the emitter of the control transistor.