RU2332785C2 - Voltage switchboard with current overload protection - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: device contains load current sensor, electronic key, load block, RS-trigger, OR circuit and current overload protection unit, connection input of voltage switchboard, disconnection input of voltage switchboard, data output, exclusive OR circuit and D-trigger, data input D-trigger is connected to output of voltage source corresponding to logic 1, clock input of D-trigger is connected to RS-trigger output, reset input of D-trigger is connected to output of OR circuit, D-trigger output is connected to driving input of electronic key, the first input of exclusive OR circuit is connected to output of RS-trigger, the second input of exclusive OR logic is connected to D-trigger output, and output of exclusive OR logic is connected to data output of voltage switchboard.

EFFECT: increased functional reliability.

1 dwg

Description

The invention relates to the field of electronic technology and can be used in switched power supplies to protect the load block, power supply and electronic switch of the voltage switch itself from overcurrent.

Known voltage stabilizer with protection against overcurrent, containing an electronic switch made on a transistor, a current sensor, a load unit and a second transistor controlling the electronic switch [1].

A disadvantage of the known device is that when the current in the load rises above the permissible one, for example, due to a failure in the load, the second transistor opens and reduces the current flowing through the electronic switch, thereby reducing the voltage across the load. This device does not completely disconnect the load from the voltage source, which in many cases is unacceptable due to the high likelihood of false signals or commands being issued by the failed device.

The closest technical solution to the proposed device is a voltage switch with the protection of the load unit from overcurrent, described in [2]. This voltage switch contains an electronic key and a load current sensor connected in series with the load unit, as well as an RS-flip-flop and an overcurrent protection unit, which, through the OR circuit, switches off the switch during any overcurrent.

A disadvantage of the known device is its functional uncertainty and that after turning on the load, overcurrent protection (for example, during a short circuit in the load unit or during overload during operation) and turning off the voltage switch, the control system does not receive timely information about it. In addition, it is possible to re-enable the load block with the input signal if the input signal has a sufficient duration. This situation occurs when you try to re-enable until the emergency condition in the load block is eliminated (causes of overcurrent). In this case, after overcurrent and emergency shutdown of the electronic key and load, multiple overloads will occur, reducing the reliability of the equipment as a whole. Such a state in a real situation cannot be detected immediately, but is detected only after a sufficiently long time has elapsed by signs related to adjustable parameters, in particular, by temperature deviations beyond the permissible limits if this device operates in a temperature control system. In addition, it is possible (although unlikely) to falsely turn off or turn on the trigger and the load block from interference. In the absence of information about the defect, the functional reliability of the control system in which the device is applied is reduced, since there is no operational information about the failure, used, for example, to switch to the reserve.

The objective of the invention is the increase in functional reliability due to the formation of an information signal about the disconnection of the load due to overcurrent while eliminating the re-inclusion of the load after the operation of the protection against overcurrent.

This problem is solved in that in the voltage switch with protection against overcurrent, containing a series-connected load current sensor and an electronic key connected to the load unit, an RS-flip-flop, an OR circuit and an overcurrent protection unit, while the switch on input is voltage is connected to the RS-trigger installation input, the voltage switch off input is connected to the first input of the OR circuit, the output of the load current sensor is connected to the input of the overcurrent protection block, the output of the overcurrent protection block is connected is connected to the second input of the OR circuit, an information output is entered, the circuit EXCLUSIVE OR and the D-trigger, the data input of the D-trigger is connected to the output of the voltage source corresponding to a logical unit, the synchronization input of the D-trigger is connected to the output of the RS-trigger, the reset input is D- the trigger is connected to the output of the OR circuit, the output of the D-trigger is connected to the control input of the electronic key, the first input of the circuit EXCLUSIVE OR is connected to the output of the RS-trigger, the second input of the logic element EXCLUSIVE OR is connected to the output of the D-trigger, and the output of the logical electronic ment exclusive OR data output connected to a voltage switch.

The drawing shows a block diagram of a voltage switch with overcurrent protection, while in the drawing and further in the text are indicated:

1 - input switch voltage;

2 - input switch off the voltage switch;

3 - electronic key (CE);

4 - load unit;

5 - load current sensor;

6 - RS-trigger;

7 is an OR diagram;

8 - D-trigger;

9 - block overcurrent protection;

10 is an EXCLUSIVE OR diagram;

11 - information output;

12 - control system;

U is the switched supply voltage;

E is the voltage corresponding to a logical unit;

U _S - input switching signals of the switch;

U _R - input switch off signals;

I _H - load current;

0 - common bus power sources ("ground").

The voltage switch with overcurrent protection is as follows.

The load current sensor 5, the electronic switch 3 and the load unit 4 are connected in series and connected to the power supply source U. The input 1 of the voltage switch is connected to the input S of the RS-trigger 6 installation, and the input 2 of the voltage switch 2 is connected to the first input of the OR circuit 7 The output of the load current sensor 5 is connected to the input of the overcurrent protection unit 9, the output of which is connected to the second input of the OR circuit. The data input of the D-trigger 8 is connected to the output of the voltage source E corresponding to a logical unit, the synchronization input C of this trigger is connected to the output Q of the RS-trigger 6, and the reset input R of the D-trigger is connected to the output of the OR circuit 7. Output Q of the D-trigger 8 is connected to the control input of the electronic key 3. The inputs of the circuit EXCLUSIVE OR 10 are connected to the output of the RS-trigger and the output of the D-trigger, and its output is connected to the information output of the voltage switch 11.

The voltage switch with overcurrent protection operates as follows.

When voltage is applied, the triggers of the device are restored to their initial (off) state. This can be done by a pulse at the turn-off input 2 of the voltage switch formed by the control system 12. As a result, a logic zero from the output of the D-flip-flop 8 keeps the electronic key 3 closed and the load unit 4 turns off. The output voltage from the load current sensor 5, equal to zero, is fed to the input of the protection unit 9, the output of which the signal is also equal to zero. In this state, both input signals of the EXCLUSIVE OR 10 circuit are equal to zero and the output signal in accordance with the logic of its operation is zero: at the information output 11 of the device, the signal is also equal to zero.

By the signal U _S = 1 supplied to the input 1 of the voltage switch on, the trigger 6 is set to a single state and its output signal at the synchronization input C of the D-trigger transfers the D-trigger to the on state. The output signal of the D-trigger includes an electronic switch 3, which, in turn, closes the power supply circuit of the load unit 4. If the load current I _H at this moment is within the specified limits, then the input of the protection unit 9 has a low voltage level and the output of the protection unit 9 logical zero. Load block 4 is turned on in nominal mode. In this state, both inputs of the EXCLUSIVE OR 10 circuit are equal to unity, and its output signal at the information output of the device 11 remains equal to zero. However, if the load current I _H at the moment of its switching on (or in the operating mode) is excessively high (for example, a short circuit in the load block 4 or overcurrent during operation), then the protection block 9 is also triggered by the output pulse through the circuit: output protection unit 9 - OR circuit 7 - input R of the D-flip-flop 8 resets the D-flip-flop. In this case, the electronic key 3 is closed and the load unit 4 is disconnected from the power supply U. The device automatically disconnects the load unit with a current exceeding the permissible current. In this state, one input signal of the EXCLUSIVE OR 10 circuit coming from the output of the RS-flip-flop is equal to one, and the second input signal of the circuit EXCLUSIVE OR 10 coming from the output of the D-flip-flop is zero and its output signal and the signal at the information output 11 of the device becomes equal to one. This logical unit, which is input to the control system 12, notifies that an accident has occurred in the load block switched by this device. In this case, it is necessary to switch to the reserve or eliminate the accident that occurred (if it is possible or available).

After an emergency shutdown of the load unit, it cannot be switched on again by a command at the switching-on input, since the RS trigger does not change its state from the repeated signal at the switching-on input 1 of the switch, the logic level at the synchronization input of the D-trigger is always high and its state always remains unchanged, and the electronic key is turned off. To re-enable the voltage switch, you must first apply a pulse to the turn-off input 2 of the voltage switch, set the RS-trigger 6 to its original state, and only after that the voltage switch can be turned on by the pulse at input 1.

In nominal operation load off unit 4 is produced by applying a voltage switch off the pulse input 2 U _R = 1, which resets the RS-flip-flop 6, and passing in parallel through OR gate 7, resets the D-flip-flop 8.

Compared with the known voltage switch [2], the present invention increases the functional reliability of the device and control system in which it is applied by generating an alarm signal, which can be used, for example, to switch to the reserve, and eliminating the possibility of unauthorized re-switching of the load unit after an emergency shutdown.

The proposed set of features in the proposal considered by the author has not been met before to solve the problem and does not follow explicitly from the prior art, which allows us to conclude that the technical solution meets the criteria of "novelty" and "inventive step".

As elements for the implementation of the device, serial microcircuits with the necessary set of functions can be used, for example, 564 series microcircuits, standard comparators, for example, 521 series, electronic keys of the required power (the most promising are field-effect transistors that require minimal control power and are in good agreement with microcircuits ) Depending on the type of electronic key and its control logic, an inverter can be switched on between the output of the D-trigger and the control input of the key, or the control signal can be supplied to the input of the electronic key from the inverting output of the D-trigger. This does not change the essence of the invention.

Literature

1. Sources of power for electronic equipment. Handbook edited by G.S. Naivelt. Moscow, Radio and Communications, 1986, p. 189, Fig. 5.19.

2. Description of the invention to the patent of the Russian Federation No. 2208292, H03K 17/08.

Claims (1)

A voltage switch with overcurrent protection, containing a series-connected load current sensor and an electronic key connected to the load unit, an RS trigger, an OR circuit and an overcurrent protection unit, while the input of the voltage switch is connected to the input of the RS- installation trigger, the switch off voltage input is connected to the first input of the OR circuit, the output of the load current sensor is connected to the input of the overcurrent protection block, the output of the overcurrent protection block is connected to the second input of the IL circuit characterized in that it is provided with an information output and an EXCLUSIVE OR circuit and a D-trigger are introduced into it, the data input of the D-trigger is connected to the output of the voltage source corresponding to a logical unit, the synchronization input of the D-trigger is connected to the output of the RS-trigger, reset input The D-trigger is connected to the output of the OR circuit, the output of the D-trigger is connected to the control input of the electronic key, the first input of the circuit EXCLUSIVE OR is connected to the output of the RS-trigger, the second input of the logic element EXCLUSIVE OR is connected to the output of the D-trigger, and the output is nical EXCLUSIVE OR gate is connected to the data output voltage of the switch.