RU2304343C1 - Solid load controller - Google Patents

Abstract

FIELD: switching of DC power networks.

SUBSTANCE: the controller consists of buffer (1), galvanic decoupling assembly (2) control and protection assembly (3), voltage conversion assembly (4), switch (5) and time-delay assembly (6).

EFFECT: provided in-line monitoring of the present condition of load current, reduced power consumption, expanded field of application, simplified controller construction and, as a result, reduced cost.

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Description

Solid state load controller refers to electronic switching technology and can be used for switching power DC power networks.

A known solid-state controller containing a buffer, a galvanic isolation unit, a control and protection unit, a voltage conversion unit, the first input of which is connected to a power source, and the output is connected to the second input of the control and protection unit, a switch, a second input and a second output of which are connected respectively to the first output and the first input of the control and protection unit, and the first input and the first output are respectively the output and input of the switching device circuit (load circuit), the second and third outputs and the third input of the unit and the controls and protections are connected respectively to the inputs and outputs of the galvanic isolation node, and the other outputs and inputs of the isolation node are connected respectively to the inputs and outputs of the buffer, the outputs of which are the status outputs of the device, and the input is the control input of the device (ENGINEERING DATA SHEET, F. LEACH INTERNATIONAL, North America, Volume V - Solid State Power Controller, page 20, date of issue: 10/98).

A disadvantage of the known controller is the limited scope, due to the inability to independently turn on after an emergency shutdown.

A known solid-state controller containing a buffer, a galvanic isolation unit, a control and protection unit, a voltage conversion unit, a disconnection unit and an identification unit, a first input of a voltage conversion unit is connected to a power source, and an output is connected to a second input of a control and protection unit, a switch, an input which is connected to the first output of the control and protection unit, and the first input and second output are the input and output of the power circuit of the device, the second output of the control and protection unit is connected to the input of the galvanic unit isolation, the output of the galvanic isolation node is connected to the input of the buffer, the output of which is the status output of the device (RF patent No. 2256282, IPC 7 Н02М 3/08).

The known controller is closest in essence to the claimed invention and is selected as the closest analogue (prototype).

The disadvantage of this controller is the inability to control the switch-off and switch-on times, which may be necessary when working on a reactive load (capacitive, inductive, motor, lamp), causing inrush currents in the switched circuit when it closes or opens to prevent false protection from over current. Another disadvantage of the controller is the complexity and, as a consequence, the high cost of the device due to the presence of the load identification node. This unit is built on the basis of an analog-to-digital converter that generates a serial digital code proportional to the current value in the load circuit switched by the controller. The need to decode this code to determine the magnitude of the load current also complicates the controller control circuit, and also requires additional time, which can be critical if necessary, quickly disconnect the load circuit in an emergency.

The technical result of the claimed invention is expressed in expanding its scope by providing the ability to control the on / off time of the switch, as well as in simplifying and, as a consequence, reducing the cost.

To solve this problem, a solid-state load controller containing a buffer, a galvanic isolation unit, a control and protection unit, a voltage conversion unit, the first input of which is connected to an external power source, and the output is connected to the first input of the control and protection unit, a switch, the second input of which connected to the first output of the control and protection unit, and the first input and output are the input and output of the power circuit of the device, the second output of the control and protection unit is connected to the input of the galvanic isolation unit, you One galvanic isolation node is connected to the input of the buffer, the output of which is the device status output, a time delay node is introduced, the input of which is connected to the output of the voltage conversion unit, and the output is connected to the second input of the control and protection unit, the third input of which is connected to the second output of the switch, the second input of the voltage conversion unit is the control input of the device, and the third input is the reset input of the device.

The drawing shows a structural diagram of a solid-state load controller.

The solid-state load controller consists of a buffer 1, made on the basis of level matching chips, a galvanic isolation node 2, made on the basis of optocouplers, transformers, etc., a control and protection unit 3, consisting of an output key control circuit (current transistor amplifier) and a circuit for comparing voltage with reference values (based on comparators), which can be implemented both on the basis of discrete elements and on the LSI of the base matrix crystal, node 4 of the voltage conversion, consisting of a series of a pulse generator (based on microcircuits), a step-up transformer and a rectifier (based on diodes and zener diodes), a switch 5 consisting of a series-switched key circuit (based on power transistors) and a current sensor (for example, a current-voltage converter with a low resistance resistor) ), node 6 of the time delay, which can be constructed according to the single-vibrator scheme (both on discrete elements and on the LSI of the base matrix crystal) with a time-varying RC circuit that determines the delay of the output signal ala respect to the input node.

Solid state load controller works as follows.

When power is supplied to the first input and there is no reset signal at the third input of the voltage conversion unit 4, the pulse generator of this unit is started. To turn on the device, a control signal is supplied to the second input of the voltage conversion unit 4. In this case, the conversion of the pulses generated by the generator through the transformer and the rectifier into the output DC voltage is allowed, which provides power to the control and protection unit 3 and the time delay unit 6, which after a certain time forms an enable signal. In the presence of this signal, the control and protection unit 3 issues a unlocking signal to the switch 5, which leads to the operation of a key that closes the load circuit. In this case, the current entering through the first input and exiting through the first output of the switch 5 flows through the switch and the current sensor, the value of which is determined by the load resistance in the circuit switched by the device. The voltage removed from the current sensor and proportional to the load current is issued from the switch 5 to the comparison circuit of the control and protection unit 3. If the load current exceeds the maximum permissible value (and, accordingly, the voltage received from the current sensor, a threshold value), the control and protection unit 3 issues a corresponding signal to the galvanic isolation unit 2. After galvanic isolation on the power supply of this signal, it is output from the galvanic isolation node 2 to buffer 1, where it is normalized by voltage levels and current amplification, and then it is output to an external circuit from the device status output. If the load current does not exceed the maximum permissible value, then the device status signal is not generated.

The presence of a signal at the third input of the voltage conversion unit 4 (input of the device reset) stops its generator and ensures that the device switches to storage mode with all its components switched off and the output key is locked. If overload protection is not required, the reset input can be left unconnected.

If, when the load current exceeds the limit values, it is necessary to open the switched circuit (locking the output key of the device), then the status output and the reset input of the device must be electrically connected to each other. When they are directly connected (by a current conductor), a minimum device shutdown delay is provided, which is determined by its speed. After the device is turned off, the status signal disappears, which automatically leads to the device unlocking (by the loss of the signal at the reset input) and its re-inclusion (if there is a control signal at the second input of the voltage conversion unit 4). Thus, with current overload in the switching circuit, the device is turned on / off cyclically. At the same time, the time the switched circuit is under current is two orders of magnitude less than the time of the de-energized state (due to the turn-on delay provided by the time delay unit 6), which prevents the load circuit and the switching element from failing.

Due to switching transients (capacitive load) or in the case of a change in the load resistance (for example, switching on a cold filament), the initial values of the switched current can significantly (by an order of magnitude) exceed the current value of the steady state. In such cases, you can increase the delay off the device (from the appearance of the signal at the status output to its supply to the reset input) to stabilize the load circuit parameters. The delay can be either hardware (on analog elements, for example, integrating RC circuits, or digital, for example, pulse counters), and program (for example, transmitting the device status signal to a microprocessor system with a software delay time countdown and issuing a controller shutdown signal to its input reset).

Thus, the introduction of a time delay unit into the device with appropriate connections provides the possibility of real-time monitoring of the current state of the load current and control of the on / off time of the device switch in circuits with different values and nature of the load while reducing energy consumption when switching to storage mode, which allows significantly expand the scope of the controller, simplify and, as a result, reduce its cost.

Claims (1)

A solid-state load controller containing a buffer, a galvanic isolation unit, a control and protection unit, a voltage conversion unit, the first input of which is connected to an external power source, and the output is connected to the first input of the control and protection unit, a switch, the second input of which is connected to the first output of the unit control and protection, and the first input and output are the input and output of the power circuit of the device, the second output of the control and protection unit is connected to the input of the galvanic isolation node, the output of the galvanic isolation node with connected to the input of the buffer, the output of which is the status output of the device, characterized in that a time delay unit is introduced, the input of which is connected to the output of the voltage conversion unit, and the output is connected to the second input of the control and protection unit, the third input of which is connected to the second output of the switch, the second input of the voltage conversion unit is the control input of the device, and the third input is the reset input of the device.