Normally-closed solid-state switch circuit based on optical isolation

Abstract

The invention discloses a normally-closed solid-state switching circuit based on optical isolation, which comprises a voltage division circuit, a filter circuit, an input isolation device and a switching device which are connected in parallel, and is characterized in that the input end of the voltage division circuit is connected with a photoelectric coupler, and the input end of the photoelectric coupler is connected to a control end for power supply through a current control device; the voltage division circuit provides driving voltage for the switching device; the circuit is simple, reliable and low in cost, a control circuit and an electrical execution circuit can be electrically isolated, the reliability of circuit control is improved, the service life is prolonged, the function of an electromechanical normally-closed contact type electromagnetic relay is replaced, the application range is wider, and the application range is wider. And the application requirements of equipment with harsh use environment, larger vibration quantity value and high reliability requirement are met.

Description

Technical Field

[0001] The invention relates to the field of normally closed solid-state switch circuits, in particular to a normally closed solid-state switch circuit based on optical isolation. Background Art

[0002] In order to ensure the reliable conversion of single-channel normally closed power amplifier in the application equipment in the fields of industry, aerospace, etc., it is generally realized by using traditional electromechanical break contact type electromagnetic relay as solid-state switch circuit. However, due to the limitations of its own structure and technology, electromechanical electromagnetic relay / contactor has low reliability, short service life, slow conversion speed, poor environmental adaptability, poor vibration resistance and other problems. It cannot be applied to equipment with large vibration value and high reliability requirements. Therefore, a normally closed solid-state switch circuit based on optical isolation is proposed. Summary of the invention

[0003] The purpose of the present invention is to provide a normally closed solid-state switch circuit based on optical isolation to solve the problems of low reliability, short service life, slow conversion speed and poor environmental adaptability of the existing solid-state switch circuit mentioned in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solutions: A normally closed solid-state switch circuit based on optical isolation includes a voltage divider circuit, a filter circuit, an input isolation device and a switch device connected in parallel, wherein the input end of the voltage divider circuit is connected to a photoelectric coupler, and the input end of the photoelectric coupler is connected to a control end for power supply through a current control device; The voltage divider circuit provides a driving voltage for the switching device. The output end of the voltage divider circuit is connected to resistors R7 and R8 for ensuring the effectiveness of power supply, and the output ends of resistors R7 and R8 are connected to a filter circuit. An isolation device is input in parallel between the voltage divider circuit and the filter circuit; one end of the switching device is connected to a power supply or a power output.

[0005] Furthermore, the current control device includes a resistor R1 and a resistor R2 connected to the input end of the photocoupler, and the resistor R1 and the resistor R2 are used to control the input current of the control end power supply to ensure the normal operation of the switching device. The voltage divider circuit includes a resistor R3, a resistor R4, a resistor R5, a resistor R6, a diode D2 and a diode D3, and the voltage divider circuit is used to divide the input voltage of the photocoupler.

[0006] Furthermore, the input isolation device includes a diode D1 and a diode D5, the output ends of the diode D1 and the diode D5 are grounded GND, and the diode D1 and the diode D5 are used for isolating the power input to avoid a power input short circuit.

[0007] Furthermore, the switching device includes a field effect transistor assembly consisting of a field effect transistor Q1 and a field effect transistor Q2, the gate of the field effect transistor Q1 is connected to a Zener diode D2, and the gate of the field effect transistor Q2 is connected to a Zener diode D3, and the Zener diode D2 and the Zener diode D3 are used to increase the input voltage of the power end.

[0008] Furthermore, the filter circuit is used to perform RC filtering on the power electricity, and the filter circuit includes a resistor R9 and a capacitor C1.

[0009] The beneficial effects of the present invention are as follows: the circuit of the present invention is simple, reliable and low-cost, can be used for product equipment that has requirements for power amplification conversion control, has the characteristics of high reliability, long life, fast conversion speed, strong environmental adaptability and strong vibration resistance, can electrically isolate the control circuit and the electrical execution circuit, improve the reliability of circuit control and increase the service life, replace the function of the electromechanical break contact type electromagnetic relay, have a wider range of applications, and meet the application needs of equipment with harsh operating environments, large vibration values ​​and high reliability requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 The present invention is based on the optical isolation type normally closed solid-state switch circuit diagram.

[0011] In the figure: 1 control end power supply, 2 photocoupler, 3 field effect tube assembly, 4 power end power supply, 5 power end output. DETAILED DESCRIPTION

[0012] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] See also Figure 1, which provides a technical solution for the present invention, a normally closed solid-state switch circuit based on optical isolation, including a parallel voltage divider circuit, a filter circuit, an input isolation device and a switch device, the input end of the voltage divider circuit is connected to a photoelectric coupler 2, the input end of the photoelectric coupler 2 is connected to the control end power supply 1 through a current control device, and the control end power supply 1 is connected to a 28V voltage; the voltage divider circuit mentioned provides a driving voltage for the switch device, the output end of the voltage divider circuit is connected to a resistor R7 and a resistor R8 for ensuring the effectiveness of the power supply, and the output ends of the resistors R7 and R8 are connected to a filter circuit, and an input isolation device is connected in parallel between the voltage divider circuit and the filter circuit; wherein, one end of the switch device is connected to a power end power supply 4 or a power end output 5; the role of the resistors R7 and R8 is to provide a zero point potential for the back-to-back switch devices to ensure the effectiveness of the power output voltage.

[0014] Among them, the switching device mentioned includes a field effect transistor assembly 3 composed of a field effect transistor Q1 and a field effect transistor Q2, the gate of the field effect transistor Q1 is connected to a Zener diode D2, and the gate of the field effect transistor Q2 is connected to a Zener diode D3; the field effect transistor Q1 and the field effect transistor Q2 mentioned are but not limited to C100N30S5 field effect transistors.

[0015] It should be noted that the filter circuit mentioned is used for RC filtering of power electricity, and the filter circuit includes a resistor R9 and a capacitor C1; the field effect transistor Q1 and the field effect transistor Q2 mentioned function as switches to bear the load current; wherein, the Zener diode D2 and the Zener diode D3 are used to increase the input voltage of the power end, thereby making the power input current reach the saturation value; the photoelectric coupler 2 mentioned is represented by the U1 device, which is the core functional device of a single-channel normally closed solid-state switch circuit, and its function is to constitute an isolation circuit of the solid-state switch, and the photoelectric coupler 2 adopts but is not limited to the GH281-2 photocoupler.

[0016] In this embodiment, the current control device mentioned includes resistors R1 and R2 connected to the input end of the photocoupler 2, and the resistors R1 and R2 are used to control the input current of the control end power supply 1 to ensure the normal operation of the switching device. The voltage divider circuit includes resistors R3, R4, R5, R6, diodes D2 and D3, and the voltage divider circuit is used to divide the input voltage of the photocoupler 2.

[0017] In this embodiment, the input isolation device includes a diode D1 and a diode D5 , the output ends of the diode D1 and the diode D5 are grounded GND, and the diode D1 and the diode D5 are used for power input isolation to prevent power input short circuit.

[0018] The optically isolated normally closed solid-state switch circuit realizes the function of a single-channel normally closed power amplifier circuit through three devices: a photoelectric coupler 2, a resistor, a diode, a capacitor, a voltage-stabilizing diode, and a field effect tube assembly. The photoelectric coupler 2 and the resistor are used to realize the isolation of the low-voltage control circuit and the high-power output voltage. The field effect tube Q1, the field effect tube Q2, the voltage-stabilizing diode, the resistor, and the capacitor are used to realize the power amplification output function. The optically isolated normally closed solid-state switch circuit, when a voltage of 28V is input to the photoelectric coupler 2, and as the input voltage increases, the conduction degree of the photoelectric coupler 2 gradually increases, and when the required conduction threshold is reached, U1 is turned on, thereby causing the field effect tube Q1 and the field When the field effect tube Q2 is turned on, the solid-state switch controls the shutdown, thereby converting the channel from a normally closed state to a normally open state; the field effect tube Q1 and the field effect tube Q2 are connected back to back, so that the solid-state switch has a bidirectional input and output characteristic, that is, 28V-A1 and 28V-A2 can be used as power input terminals, that is, power supply terminals 4, and can also be used as power outputs 5, thereby realizing the non-polarity requirement of the power terminal; when the solid-state switch circuit returns after being turned on, when the input voltage gradually decreases, and the conduction degree of the optocoupler 2 gradually decreases, when the shutdown threshold is reached, U1 is turned off, thereby causing the field effect tube Q1 and the field effect tube Q2 to be disconnected, and the circuit will be quickly turned off to realize the shutdown control of the solid-state switch.

[0019] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0020] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be understood that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. In the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", "connection", "fixation" and the like should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection, or integrated; it can be a mechanical connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two components or the interaction relationship between two components; among them, there are many ways of detachable installation, for example, it can be through the way of plug-in and snap-fit, for example, through the way of bolt connection, etc.

[0021] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A normally closed solid-state switch circuit based on optical isolation, characterized in that: It includes a voltage divider circuit, a filter circuit, an input isolation device and a switch device connected in parallel, wherein the input end of the voltage divider circuit is connected to a photoelectric coupler, and the input end of the photoelectric coupler is connected to the control end for power supply through a current control device; The voltage divider circuit provides a driving voltage for the switching device. The output end of the voltage divider circuit is connected to resistors R7 and R8 for ensuring the effectiveness of power supply, and the output ends of resistors R7 and R8 are connected to a filter circuit. An isolation device is input in parallel between the voltage divider circuit and the filter circuit; one end of the switching device is connected to a power supply or a power output.

2. The optically isolated normally closed solid-state switch circuit according to claim 1, characterized in that: The current control device includes a resistor R1 and a resistor R2 connected to the input end of the photocoupler, and the resistor R1 and the resistor R2 are used to control the input current of the control end power supply to ensure the normal operation of the switching device. The voltage divider circuit includes a resistor R3, a resistor R4, a resistor R5, a resistor R6, a diode D2 and a diode D3, and the voltage divider circuit is used to divide the input voltage of the photocoupler.

3. The optically isolated normally closed solid-state switch circuit according to claim 1, characterized in that: The input isolation device comprises a diode D1 and a diode D5 , the output ends of the diode D1 and the diode D5 are grounded GND, and the diode D1 and the diode D5 are used for isolating the power input to avoid a short circuit of the power input.

4. The optically isolated normally closed solid-state switch circuit according to claim 1, characterized in that: The switch device includes a field effect transistor assembly consisting of a field effect transistor Q1 and a field effect transistor Q2. The gate of the field effect transistor Q1 is connected to a voltage-stabilizing diode D2, and the gate of the field effect transistor Q2 is connected to a voltage-stabilizing diode D3. The voltage-stabilizing diode D2 and the voltage-stabilizing diode D3 are used to increase the input voltage of the power end.

5. The optically isolated normally closed solid-state switch circuit according to claim 1, characterized in that: The filter circuit is used for performing RC filtering on the power electricity, and the filter circuit comprises a resistor R9 and a capacitor C1.

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